Sediment Dating With 210Pb and 137Cs In Monterey Canyon, California Reveal the extent of recent sediment movement down canyon

NASA Astrophysics Data System (ADS)

Lorenson, T. D.; Maier, K. L.; Gwiazda, R.; Paull, C. K.; McGann, M.

2017-12-01

Submarine canyons are major vectors of sediment transport off the continent into the deep sea. Recent results from the Monterey Coordinated Canyon Experiment document fifteen sediment transport events occurred during an 18-month period from 2015 to 2017, and three of them reached at least to 1850m. In an attempt to constrain the timing and rate in which sediments were transported down canyons in these and earlier events we have collected sediment cores and measured the sedimentation rates using 210Pb and 137Cs dating techniques along the axis of Monterey Canyon. We employed transects of precisely located ROV collected push cores and vibracores collected at water depths ranging from 300m to 2900m perpendicular to the canyon axis using a remotely operated vehicle (ROV). Some cores were taken in 2013 and compared with those taken in 2017. We focused on cores from terraces that are between 60m and 75m above the canyon thalweg in water depths between 300 and 1500 m and in cores collected form the canyon's axial channel between 1800 and 2900 m water depths where the canyon widens considerably. Generally sedimentation rates vary with depth, with the highest sedimentation rate closest to land, but vary substantially across successive terraces. Sawtooth-shaped excess 210Pb and 137Cs profiles with depth at almost all sites at least to 1500m imply several episodes of deposition and reworking of sediment on the terraces suggesting multiple sediment transport events. The excess 210Pb in many cores reach depths of up to 1m implying sedimentation rates greater than 10mm per year. At the deepest site (2900m) about 10 cm of fine hemipelagic sediment overlies sand indicating a high-energy sediment flow event. In 2014 the measured 210Pb sedimentation rate of 0.6 to 0.8mm per year indicates that the last 10 cm of sediment have been deposited and undisturbed since about the year 1910 showing that recent events have not reached this depth. Measurements are on going to determine if the 2015-2017 sediment transport events have travelled down to 2900m [RG1] and if the timing of these sediment flow events were triggered by external factors, like earthquakes, winter storms, or by seafloor failures within the Canyon. [RG1]This seem to contradict the previous sentence where it says that it did not reach 2900 m

Use of sediment source fingerprinting to assess the role of subsurface erosion in the supply of fine sediment in a degraded catchment in the Eastern Cape, South Africa.

PubMed

Manjoro, Munyaradzi; Rowntree, Kate; Kakembo, Vincent; Foster, Ian; Collins, Adrian L

2017-06-01

Sediment source fingerprinting has been successfully deployed to provide information on the surface and subsurface sources of sediment in many catchments around the world. However, there is still scope to re-examine some of the major assumptions of the technique with reference to the number of fingerprint properties used in the model, the number of model iterations and the potential uncertainties of using more than one sediment core collected from the same floodplain sink. We investigated the role of subsurface erosion in the supply of fine sediment to two sediment cores collected from a floodplain in a small degraded catchment in the Eastern Cape, South Africa. The results showed that increasing the number of individual fingerprint properties in the composite signature did not improve the model goodness-of-fit. This is still a much debated issue in sediment source fingerprinting. To test the goodness-of-fit further, the number of model repeat iterations was increased from 5000 to 30,000. However, this did not reduce uncertainty ranges in modelled source proportions nor improve the model goodness-of-fit. The estimated sediment source contributions were not consistent with the available published data on erosion processes in the study catchment. The temporal pattern of sediment source contributions predicted for the two sediment cores was very different despite the cores being collected in close proximity from the same floodplain. This highlights some of the potential limitations associated with using floodplain cores to reconstruct catchment erosion processes and associated sediment source contributions. For the source tracing approach in general, the findings here suggest the need for further investigations into uncertainties related to the number of fingerprint properties included in un-mixing models. The findings support the current widespread use of ≤5000 model repeat iterations for estimating the key sources of sediment samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

Grain-size distribution and selected major and trace element concentrations in bed-sediment cores from the Lower Granite Reservoir and Snake and Clearwater Rivers, eastern Washington and northern Idaho, 2010

USGS Publications Warehouse

Braun, Christopher L.; Wilson, Jennifer T.; Van Metre, Peter C.; Weakland, Rhonda J.; Fosness, Ryan L.; Williams, Marshall L.

2012-01-01

Fifty subsamples from 15 cores were analyzed for major and trace elements. Concentrations of trace elements were low, with respect to sediment quality guidelines, in most cores. Typically, major and trace element concentrations were lower in the subsamples collected from the Snake River compared to those collected from the Clearwater River, the confluence of the Snake and Clearwater Rivers, and Lower Granite Reservoir. Generally, lower concentrations of major and trace elements were associated with coarser sediments (larger than 0.0625 millimeter) and higher concentrations of major and trace elements were associated with finer sediments (smaller than 0.0625 millimeter).

St. Petersburg Coastal and Marine Science Center's Core Archive Portal

USGS Publications Warehouse

Reich, Chris; Streubert, Matt; Dwyer, Brendan; Godbout, Meg; Muslic, Adis; Umberger, Dan

2012-01-01

This Web site contains information on rock cores archived at the U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center (SPCMSC). Archived cores consist of 3- to 4-inch-diameter coral cores, 1- to 2-inch-diameter rock cores, and a few unlabeled loose coral and rock samples. This document - and specifically the archive Web site portal - is intended to be a 'living' document that will be updated continually as additional cores are collected and archived. This document may also contain future references and links to a catalog of sediment cores. Sediment cores will include vibracores, pushcores, and other loose sediment samples collected for research purposes. This document will: (1) serve as a database for locating core material currently archived at the USGS SPCMSC facility; (2) provide a protocol for entry of new core material into the archive system; and, (3) set the procedures necessary for checking out core material for scientific purposes. Core material may be loaned to other governmental agencies, academia, or non-governmental organizations at the discretion of the USGS SPCMSC curator.

Results of chemical and isotopic analyses of sediment and water from alluvium of the Canadian River near a closed municipal landfill, Norman, Oklahoma

USGS Publications Warehouse

Breit, George N.; Tuttle, Michele L.W.; Cozzarelli, Isabelle M.; Christenson, Scott C.; Jaeschke, Jeanne B.; Fey, David L.; Berry, Cyrus J.

2005-01-01

Results of physical and chemical analyses of sediment and water collected near a closed municipal landfill at Norman, Oklahoma are presented in this report. Sediment analyses are from 40 samples obtained by freeze-shoe coring at 5 sites, and 14 shallow (depth <1.3 m) sediment samples. The sediment was analyzed to determine grain size, the abundance of extractable iron species and the abundances and isotopic compositions of forms of sulfur. Water samples included pore water from the freeze-shoe core, ground water, and surface water. Pore water from 23 intervals of the core was collected and analyzed for major and trace dissolved species. Thirteen ground-water samples obtained from wells within a few meters of the freeze-shoe core sites and one from the landfill were analyzed for major and trace elements as well as the sulfur and oxygen isotope composition of dissolved sulfate. Samples of surface water were collected at 10 sites along the Canadian River from New Mexico to central Oklahoma. These river-water samples were analyzed for major elements, trace elements, and the isotopic composition of dissolved sulfate.

Mercury profiles in sediment from the marginal high of Arabian Sea: an indicator of increasing anthropogenic Hg input.

PubMed

Chakraborty, Parthasarathi; Vudamala, Krushna; Chennuri, Kartheek; Armoury, Kazip; Linsy, P; Ramteke, Darwin; Sebastian, Tyson; Jayachandran, Saranya; Naik, Chandan; Naik, Richita; Nath, B Nagender

2016-05-01

Total Hg distributions and its speciation were determined in two sediment cores collected from the western continental marginal high of India. Total Hg content in the sediment was found to gradually increase (by approximately two times) towards the surface in both the cores. It was found that Hg was preferentially bound to sulfide under anoxic condition. However, redox-mediated reactions in the upper part of the core influenced the total Hg content in the sediment cores. This study suggests that probable increase in authigenic and allogenic Hg deposition attributed to the increasing Hg concentration in the surface sediment in the study area.

Estimation of a Historic Mercury Load Function for Lake Michigan using Dated Sediment Cores

EPA Science Inventory

Box cores collected between 1994 and 1996 were used to estimate historic mercury loads to Lake Michigan. Based on a kriging spatial interpolation of 54 Pb-210 dated cores, 228 metric tons of mercury are stored in the lake’s sediments (excluding Green Bay). To estimate the time ...

Clostridium perfringens in Long Island Sound sediments: An urban sedimentary record

USGS Publications Warehouse

Buchholtz ten Brink, Marilyn R.; Mecray, E.L.; Galvin, E.L.

2000-01-01

Clostridium perfringens is a conservative tracer and an indicator of sewage-derived pollution in the marine environment. The distribution of Clostridium perfringens spores was measured in sediments from Long Island Sound, USA, as part of a regional study designed to: (1) map the distribution of contaminated sediments; (2) determine transport and dispersal paths; (3) identify the locations of sediment and contaminant focusing; and (4) constrain predictive models. In 1996, sediment cores were collected at 58 stations, and surface sediments were collected at 219 locations throughout the Sound. Elevated concentrations of Clostridium perfringens in the sediments indicate that sewage pollution is present throughout Long Island Sound and has persisted for more than a century. Concentrations range from undetectable amounts to 15,000 spores/g dry sediment and are above background levels in the upper 30 cm at nearly all core locations. Sediment focusing strongly impacts the accumulation of Clostridium perfringens spores. Inventories in the cores range from 28 to 70,000 spores/cm2, and elevated concentrations can extend to depths of 50 cm. The steep gradients in Clostridium perfringens profiles in muddier cores contrast with concentrations that are generally constant with depth in sandier cores. Clostridium perfringens concentrations rarely decrease in the uppermost sediment, unlike those reported for metal contaminants. Concentrations in surface sediments are highest in the western end of the Sound, very low in the eastern region, and intermediate in the central part. This pattern reflects winnowing and focusing of Clostridium perfringens spores and fine-grained sediment by the hydrodynamic regime; however, the proximity of sewage sources to the westernmost Sound locally enhances the Clostridium perfringens signals.

Archive of sediment data from vibracores collected in 2010 offshore of the Mississippi barrier islands

USGS Publications Warehouse

Kelso, Kyle W.; Flocks, James G.

2015-01-01

Selection of the core site locations was based on geophysical surveys conducted around the islands from 2008 to 2010. The surveys, using acoustic systems to image and interpret the nearsurface stratigraphy, were conducted to investigate the geologic controls on island evolution. This data series serves as an archive of sediment data collected from August to September 2010, offshore of the Mississippi barrier islands. Data products, including descriptive core logs, core photographs, results of sediment grain-size analyses, sample location maps, and geographic information system (GIS) data files with accompanying formal Federal Geographic Data Committee (FDGC) metadata can be downloaded from the data products and downloads page.

Freeze shoe sampler for the collection of hyporheic zone sediments and porewater.

PubMed

Bianchin, M; Smith, L; Beckie, R

2015-01-01

The Starr and Ingleton (1992) drive point piston sampler (DPPS) design was modified by fitting it with a Murphy and Herkelrath (1996) type sample-freezing drive shoe (SFDS), which uses liquid carbon dioxide as a cryogen. Liquid carbon dioxide was used to freeze sediments in the lower 0.1 m of the core and the drive-point piston sealed the core at the top preserving the reductive-oxidation (redox) sensitive sediments from the atmosphere and maintaining natural stratigraphy. The use of nitrogen gas to provide positive pressure on the gas system blocked the ingress of water which froze on contact with the cryogen thus blocking the gas lines with ice. With this adaptation to the gas system cores could be collected at greater depths beneath the static water level. This tool was used to collect intact saturated sediment cores from the hyporheic zone of the tidally influenced Fraser River in Vancouver, British Columbia, Canada where steep geochemical and microbial gradients develop within the interface between discharging anaerobic groundwater and recharging aerobic river water. In total, 25 cores driven through a 1.5 m sampling interval were collected from the river bed with a mean core recovery of 75%. The ability to deploy this method from a fishing vessel makes the tool more cost effective than traditional marine-based drilling operations which often use barges, tug boats, and drilling rigs. © 2014, National Ground Water Association.

A chronicle of organochlorine contamination in Clear Creek, Galveston and Harris Counties, Texas, 1960-2002, as recorded in sediment cores

USGS Publications Warehouse

Mahler, Barbara J.; Van Metre, Peter

2003-01-01

Clear Creek flows through the Texas Coastal Plain from its headwaters southeast of Houston, Texas, to Clear Lake, which empties into Galveston Bay. Segments of Clear Creek were on the State of Texas 303(d) list for 1998, 1999, and 2000 as a result of a fish consumption advisory issued by the Texas Department of Health. One of the contaminants for which the fish consumption advisory was issued is the organochlorine pesticide chlordane. Chlordane is a hydrophobic (“waterfearing”) contaminant; that is, it adsorbs to sediment at concentrations much greater than those found in water. The study described here sought to answer three questions:Does chlordane occur in Clear Creek sediments at present?Is there current loading of chlordane to Clear Creek?How has occurrence of chlordane in Clear Creek changed over time?To answer these questions, the U.S. Geological Survey (USGS), in cooperation with the U.S. Environmental Protection Agency (USEPA), collected and analyzed sediment cores from Clear Creek (fig. 1). Sediment cores sometimes can be used to reconstruct historical trends in concentrations of hydrophobic contaminants (Eisenreich and others, 1989; Van Metre and others, 1997). Cores were collected from five ponds connected to Clear Creek but out of the main channel (fig. 1). Cesium-137 (137Cs) was analyzed in the cores to determine if the sediments in the cores were undisturbed and if the cores reached sediment predating 1964. The two cores that appeared most undisturbed on the basis of 137Cs profiles (see sidebar, p. 2) were further subsampled and additional samples analyzed for 137Cs, organic carbon, selected organochlorine pesticides (including chlordane), and total polychlorinated biphenyls (PCB).

Historical trends of perfluoroalkyl substances (PFASs) in dated sediments from semi-enclosed bays of Korea.

PubMed

Shen, Aihua; Lee, Sunggyu; Ra, Kongtae; Suk, Dongwoo; Moon, Hyo-Bang

2018-03-01

Information is scarce on historical trends of perfluoroalkyl substances (PFASs) in the coastal environment. In this study, four sediment cores were collected from semi-enclosed bays of Korea to investigate the pollution history, contamination profiles, and environmental burden of PFASs. The total PFAS concentrations in sediment cores ranged from 6.61 to 821 pg/g dry weight. The highest concentrations of PFASs were found in surface or sub-surface sediments, indicating on-going contamination by PFASs. Historical trends in PFASs showed a clear increase since the 1980s, which was consistent with the global PFAS consumption pattern. Concentrations of PFASs were dependent on the organic carbon content in sediment cores. PFOS and longer-chain PFASs were predominant in all of the sediment cores. In particular, a large proportion of longer-chain PFASs was observed in the upper layers of the sediment cores from industrialized coastal regions. Inventories and fluxes estimated for PFASs were similar to those for PCDD/Fs. Copyright © 2018 Elsevier Ltd. All rights reserved.

River-plume sedimentation and 210Pb/7Be seabed delivery on the Mississippi River delta front

NASA Astrophysics Data System (ADS)

Keller, Gregory; Bentley, Samuel J.; Georgiou, Ioannis Y.; Maloney, Jillian; Miner, Michael D.; Xu, Kehui

2017-06-01

To constrain the timing and processes of sediment delivery and submarine mass-wasting events spanning the last few decades on the Mississippi River delta front, multi-cores and gravity cores (0.5 and <3 m length respectively) were collected seaward of the Mississippi River Southwest Pass in 25-75 m water depth in 2014. The cores were analyzed for radionuclide activity (7Be, 210Pb, 137Cs), grain size, bulk density, and fabric (X-radiography). Core sediments are faintly bedded, sparsely bioturbated, and composed mostly of clay and fine silt. Short-term sedimentation rates (from 7Be) are 0.25-1.5 mm/day during river flooding, while longer-term accumulation rates (from 210Pb) are 1.3-7.9 cm/year. In most cores, 210Pb activity displays undulatory profiles with overall declining activity versus depth. Undulations are not associated with grain size variations, and are interpreted to represent variations in oceanic 210Pb scavenging by river-plume sediments. The 210Pb profile of one gravity core from a mudflow gully displays uniform basal excess activity over a zone of low and uniform bulk density, interpreted to be a mass-failure event that occurred 9-18 years before core collection. Spatial trends in sediment deposition (from 7Be) and accumulation (from 210Pb) indicate that proximity to the river mouth has stronger influence than local facies (mudflow gully, depositional lobe, prodelta) over the timeframe and seabed depth represented by the cores (<40 years, <3 m length). This may be explained by rapid proximal sediment deposition from river plumes coupled with infrequent tropical cyclone activity near the delta in the last 7 years (2006-2013), and by the location of most sediment failure surfaces (from mass flows indicated by parallel geophysical studies) deeper than the core-sampling depths of the present study.

Sediment data collected in 2010 from Cat Island, Mississippi

USGS Publications Warehouse

Buster, Noreen A.; Kelso, Kyle W.; Miselis, Jennifer L.; Kindinger, Jack G.

2014-01-01

Scientists from the U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, in collaboration with the U.S. Army Corps of Engineers, conducted geophysical and sedimentological surveys in 2010 around Cat Island, Mississippi, which is the westernmost island in the Mississippi-Alabama barrier island chain. The objective of the study was to understand the geologic evolution of Cat Island relative to other barrier islands in the northern Gulf of Mexico by identifying relationships between the geologic history, present day morphology, and sediment distribution. This data series serves as an archive of terrestrial and marine sediment vibracores collected August 4-6 and October 20-22, 2010, respectively. Geographic information system data products include marine and terrestrial core locations and 2007 shoreline data. Additional files include marine and terrestrial core description logs, core photos, results of sediment grain-size analyses, optically stimulated luminescence dating and carbon-14 dating locations and results, Field Activity Collection System logs, and formal Federal Geographic Data Committee metadata.

Archive of Sediment Data Collected around the Chandeleur Islands and Breton Island in 2007 and 1987 (Vibracore Surveys: 07SCC04, 07SCC05, and 87039)

USGS Publications Warehouse

Dreher, C.A.; Flocks, J.G.; Kulp, M.A.; Ferina, N.F.

2010-01-01

In 2006 and 2007, the U.S. Geological Survey (USGS) and collaborators at the University of New Orleans (UNO) collected high-resolution seismic profiles and subsurface cores around the Chandeleur and Breton Islands, Louisiana (Study Area Map). To ground-truth the acoustic seismic surveys conducted in 2006, 124 vibracores were acquired during the 07SCC04 and 07SCC05 cruises in 2007. These cores were collected within the back-barrier, nearshore, and offshore environments. The surveys were conducted as part of a post-hurricane assessment and sediment resource inventory for the Barrier Island Coastal Monitoring (BICM) project. Vibracores were collected offshore using the USGS R/V G.K. Gilbert, while the terrestrial, back-barrier, and nearshore vibracores were collected from the UNO R/V Greenhead. This report serves as an archive of sediment data from two concurrent vibracore surveys (cruises 07SCC04 and 07SCC05) from around the Breton and Chandeleur Islands in 2007 and also documents sediment data from vibracores collected offshore of the Chandeleur Islands in 1987 (cruise 87039). The 1987 vibracores were collected through the collaborated efforts of the USGS, Louisiana Geological Survey (LGS), and Alpine Ocean Seismic. Each vibracore can be identified by cruise and core number.

Depositional environment of near-surface sediments, King George Basin, Bransfield Strait, Antarctica

NASA Astrophysics Data System (ADS)

Yoon, H. I.; Park, B. K.; Chang, S. K.; Han, M. W.; Oh, J. K.

1994-03-01

Four sediment cores were collected to determine the depositional environments of the King George Basin northeast of Bransfield Strait, Antarctica. The cored section revealed three distinct lithofacies: laminated siliceous ooze derived from an increased paleoproductivity near the receding sea-ice edges, massive muds that resulted from hemipelagic sedimentation in open water, and graded sediments that originated from nearby local seamounts by turbidity currents. Clay mineral data of the cores indicate a decreasing importance of volcanic activity through time. Active volcanism and hydrothermal activity appear to be responsible for the enrichment of smectite near the Penguin and Bridgeman Islands.

A database of paleoceanographic sediment cores from the North Pacific, 1951-2016

NASA Astrophysics Data System (ADS)

Borreggine, Marisa; Myhre, Sarah E.; Mislan, K. Allison S.; Deutsch, Curtis; Davis, Catherine V.

2017-09-01

We assessed sediment coring, data acquisition, and publications from the North Pacific (north of 30° N) from 1951 to 2016. There are 2134 sediment cores collected by American, French, Japanese, Russian, and international research vessels across the North Pacific (including the Pacific subarctic gyre, Alaskan gyre, Japan margin, and California margin; 1391 cores), the Sea of Okhotsk (271 cores), the Bering Sea (123 cores), and the Sea of Japan (349 cores) reported here. All existing metadata associated with these sediment cores are documented here, including coring date, location, core number, cruise number, water depth, vessel metadata, and coring technology. North Pacific sediment core age models are built with isotope stratigraphy, radiocarbon dating, magnetostratigraphy, biostratigraphy, tephrochronology, % opal, color, and lithological proxies. Here, we evaluate the iterative generation of each published age model and provide comprehensive documentation of the dating techniques used, along with sedimentation rates and age ranges. We categorized cores according to the availability of a variety of proxy evidence, including biological (e.g., benthic and planktonic foraminifera assemblages), geochemical (e.g., major trace element concentrations), isotopic (e.g., bulk sediment nitrogen, oxygen, and carbon isotopes), and stratigraphic (e.g., preserved laminations) proxies. This database is a unique resource to the paleoceanographic and paleoclimate communities and provides cohesive accessibility to sedimentary sequences, age model development, and proxies. The data set is publicly available through PANGAEA at https://doi.org/10.1594/PANGAEA.875998.

Depositional history and inventories of polychlorinated biphenyls (PCBs) in sediment cores from an Antarctic Specially Managed Area (Admiralty Bay, King George Island).

PubMed

Combi, Tatiane; Martins, César C; Taniguchi, Satie; Leonel, Juliana; Lourenço, Rafael André; Montone, Rosalinda Carmela

2017-05-15

Temporal patterns, fluxes and inventories of polychlorinated biphenyls (PCBs) were assessed in nine sediment cores collected from selected areas of Admiralty Bay off the Antarctic Peninsula. Concentrations of total PCBs were low, but slightly higher in comparison to low-impacted, remote environments in the world, ranging from below the detection limit to 11.9ngg -1 in dry weight. PCB concentrations and inventories suggest a possible minor influence related to the nearby logistic activities, especially in the sediment core collected close to the Ferraz Station. Despite being the most remote and protected area on the planet, the Antarctic continent is no longer a pristine environment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Collection, analysis, and age-dating of sediment cores from 56 U.S. lakes and reservoirs sampled by the U.S. Geological Survey, 1992-2001

USGS Publications Warehouse

Van Metre, Peter; Wilson, Jennifer T.; Fuller, Christopher C.; Callender, Edward; Mahler, Barbara J.

2004-01-01

The U.S. Geological Survey Reconstructed Trends National Synthesis study collected sediment cores from 56 lakes and reservoirs between 1992 and 2001 across the United States. Most of the sampling was conducted as part of the National Water-Quality Assessment (NAWQA) Program. The primary objective of the study was to determine trends in particle-associated contaminants in response to urbanization; 47 of the 56 lakes are in or near one of 20 U.S. cities. Sampling was done with gravity, piston, and box corers from boats and push cores from boats or by wading, depending on the depth of water and thickness of sediment being sampled. Chemical analyses included major and trace elements, organochlorine pesticides, polychlorinated biphenyls, polycyclic aromatic hydrocarbons, cesium-137, and lead-210. Age-dating of the cores was done on the basis of radionuclide analyses and the position of the pre-reservoir land surface in the reservoir and, in a few cases, other chemical or lithologic depth-date markers. Dates were assigned in many cores on the basis of assumed constant mass accumulation between known depth-date markers. Dates assigned were supported using a variety of other date markers including first occurrence and peak concentrations of DDT and polychlorinated biphenyls and peak concentration of lead. A qualitative rating was assigned to each core on the basis of professional judgment to indicate the reliability of age assignments. A total of 122 cores were collected from the 56 lakes and age dates were assigned to 113 of them, representing 54 of the 56 lakes. Seventy-four of the 122 cores (61 percent) received a good rating for the assigned age dates, 28 cores (23 percent) a fair rating, and 11 cores (9 percent) a poor rating; nine cores (7 percent) had no dates assigned. An analysis of the influence of environmental factors on the apparent quality of age-dating of the cores concluded that the most important factor was the mass accumulation rate (MAR) of sediment: the greater the MAR, the better the temporal discretization in the samples and the less important the effects of postdepositional sediment disturbance. These age-dated sediment cores provide the basis for local-, regional-, and national-scale interpretations of water-quality trends.

Analysis of archaeal communities in Gulf of Mexico dead zone sediments.

EPA Science Inventory

Sediments may contribute significantly to Louisiana continental shelf “dead zone” hypoxia but limited information hinders comparison of sediment biogeochemistry between norm-oxic and hypoxic seasons. Dead zone sediment cores collected during hypoxia (September 2006) had higher l...

Long-term recovery of PCB-contaminated surface sediments at the Sangamo-westonl Twelvemile Creek/lake Hartwell Superfund Site.

PubMed

Brenner, Richard C; Magar, Victor S; Ickes, Jennifer A; Foote, Eric A; Abbott, James E; Bingler, Linda S; Crecelius, Eric A

2004-04-15

Natural recovery of contaminated sediments relies on burial of contaminated sediments with increasingly clean sediments over time (i.e., natural capping). Natural capping reduces the risk of resuspension of contaminated surface sediments, and it reduces the potential for contaminant transport into the food chain by limiting bioturbation of contaminated surface or near-surface sediments. This study evaluated the natural recovery of surface sediments contaminated with polychlorinated biphenyls (PCBs) at the Sangamo-Weston/Twelvemile Creek/Lake Hartwell Superfund Site (Lake Hartwell), Pickens County, SC. The primary focus was on sediment recovery resulting from natural capping processes. Total PCB (t-PCB), lead-210 (210Pb), and cesium-137 (137Cs) sediment core profiles were used to establish vertical t-PCB concentration profiles, age date sediments, and determine surface sedimentation and surface sediment recovery rates in 18 cores collected along 10 transects. Four upgradient transects in the headwaters of Lake Hartwell were impacted by historical sediment releases from three upgradient sediment impoundments. These transects were characterized by silt/ clay and sand layering. The highest PCB concentrations were associated with silt/clay layers (1.8-3.5% total organic carbon (TOC)), while sand layers (0.05-0.32% TOC) contained much lower PCB concentrations. The historical sediment releases resulted in substantial burial of PCB-contaminated sediment in the vicinity of these four cores; each core contained less than 1 mg/kg t-PCBs in the surface sand layers. Cores collected from six downgradient Lake Hartwell transects consisted primarily of silt and clay (0.91-5.1% TOC) and were less noticeably impacted by the release of sand from the impoundments. Vertical t-PCB concentration profiles in these cores began with relatively low PCB concentrations at the sediment-water interface and increased in concentration with depth until maximum PCB concentrations were measured at approximately 30-60 cm below the sediment-water interface, ca. 1960-1980. Maximum t-PCB concentrations were followed by progressively decreasing concentrations with depth until the t-PCB concentrations approached the detection limit, where sediments were likely deposited before the onset of PCB use at the Sangamo-Weston plant. The sediments containing the maximum PCB concentrations are associated with the period of maximum PCB release into the watershed. Sedimentation rates averaged 2.1 +/- 1.5 g/(cm2 yr) for 12 of 18 cores collected. The 1994 Record of Decision cleanup requirement is 1.0 mg/kg; two more goals (0.4 and 0.05 mg/kg t-PCBs) also were identified. Average surface sedimentation requirements to meet the three goals were 1.4 +/- 3.7, 11 +/- 4.2, and 33 +/- 11 cm, respectively. Using the age dating results, the average recovery dates to meet these goals were 2000.6 +/- 2.7, 2007.4 +/- 3.5, and 2022.7 +/- 11 yr, respectively. (The 95% prediction limits for these values also are provided.) Despite the reduction in surface sediment PCB concentrations, PCB concentrations measured in largemouth bass and hybrid bass filets continue to exceed the 2.0 mg/kg FDA fish tolerance level.

Identifying water-quality trends in the Trinity River, Texas, USA, 1969-1992, using sediment cores from Lake Livingston

USGS Publications Warehouse

Van Metre, P.C.; Callender, E.

1996-01-01

Chemical analyses were done on cores of bottom sediment from three locations in Lake Livingston, a reservoir on the Trinity River in east Texas to identify trends in water quality in the Trinity River using the chemical record preserved in bottom sediments trapped by the reservoir. Sediment cores spanned the period from 1969, when the reservoir was impounded, to 1992, when the cores were collected. Chemical concentrations in reservoir sediment samples were compared to concentrations for 14 streambed sediment samples from the Trinity River Basin and to reported concentrations for soils in the eastern United States and shale. These comparisons indicate that sediments deposited in Lake Livingston are representative of the environmental setting of Lake Livingston within the Trinity River Basin. Vertical changes in concentrations within sediment cores indicate temporal trends of decreasing concentrations of lead, sodium, barium, and total DDT (DDT plus its metabolites DDD and DDE) in the Trinity River. Possible increasing temporal trends are indicated for chlordane and dieldrin. Each sediment-derived trend is related to trends in water quality in the Trinity River or known changes in environmental factors in its drainage basin or both.

Trace element fluxes during the last 100 years in sediment near a nuclear power plant

NASA Astrophysics Data System (ADS)

Bojórquez-Sánchez, S.; Marmolejo-Rodríguez, A. J.; Ruiz-Fernández, A. C.; Sánchez-González, A.; Sánchez-Cabeza, J. A.; Bojórquez-Leyva, H.; Pérez-Bernal, L. H.

2017-11-01

The Salada coastal lagoon is located in Veracruz (Mexico) near the Laguna Verde Nuclear Power Plant (LVNPP). Currently, the lagoon receives the cooling waters used in the LVNPP. To evaluate the fluxes and mobilization of trace elements due to human activities in the area, two sediment cores from the coastal flood plains of Salada Lagoon were analysed. Cores were collected using PVC tubes. Sediments cores were analysed every centimetre for dating (210Pb by alpha detector) and trace metal analysis using ICP-Mass Spectrometry. The dating of both sediment cores covers the period from 1900 to 2013, which includes the construction of the LVNPP (1970's). The Normalized Enrichment Factor shows enrichment of Ag, As and Cr in both sediment cores. These enrichments correspond to the extent of mining activity (which reached a maximum in the 1900's) and to the geological setting of the coastal zone. The profiles of the element fluxes in both sediment cores reflected the construction and operation of the LVNPP; however, the elements content did not show evidence of pollution coming from the LVNPP.

Chronology from sediment cores collected in southwestern Everglades National Park, Florida

USGS Publications Warehouse

Bernhardt, C.E.; Wingard, G.L.; Willard, D.A.; Marot, M.E.; Landacre, B.; Holmes, C.W.

2013-01-01

Age model data are presented for 10 cores from the southwestern coastal mangrove zone of Everglades National Park, Florida, collected in Common Era (CE) 2004 and 2005 and used for paleoecological analysis. Carbon-14 (14C), lead-210 (210Pb), cesium-137 (137Cs), radium-226 (226Ra), and pollen biostratigraphic information is included, and age models were generated for 6 of the 10 cores. Age reversals and sediment disturbance prevented construction of age models on the remaining four cores. Four cores present a continuous record of the last 50 to 100 years, making them useful for analyzing the impacts caused by changes in water management in south Florida. These cores are Harney River 2A and Harney River 1A, Shark River 2A, and Roberts River.

Inexpensive, easy-to-construct suction coring devices usable from small boats

USGS Publications Warehouse

Onuf, Christopher P.; Chapman, Duane C.; Rizzo, William M.

1996-01-01

Collection of sediment cores in depths of 1-5 m is difficult with traditional sampling gear. Here we describe three suction coring devices constructed with readily available plumbing supplies and parts easily made from acrylic plastic and silicone sealant. The samplers have been used successfully in sediments ranging from coarse sands and shell hash to muds, highly organic deposits, and dense clays. Successful applications have ranged from contaminants analysis, toxicity testing, seagrass mapping, and assessment of sediment-microfloral interactions to sampling the infauna of surf-swept beaches.

Oscillatory erosion and transport flume with superimposed unidirectional flow

DOEpatents

Jepsen, Richard A.; Roberts, Jesse D.

2004-01-20

A method and apparatus for measuring erosion rates of sediments and at high shear stresses due to complex wave action with, or without, a superimposed unidirectional current. Water is forced in a channel past an exposed sediment core sample, which erodes sediments when a critical shear stress has been exceeded. The height of the core sample is adjusted during testing so that the sediment surface remains level with the bottom of the channel as the sediments erode. Complex wave action is simulated by driving tandom piston/cylinder mechanisms with computer-controlled stepper motors. Unidirectional flow, forced by a head difference between two open tanks attached to each end of the channel, may be superimposed on to the complex wave action. Sediment traps may be used to collect bedload sediments. The total erosion rate equals the change in height of the sediment core sample divided by a fixed period of time.

Composition and depth distribution of hydrocarbons in Barataria Bay marsh sediments after the Deepwater Horizon oil spill.

PubMed

Dincer Kırman, Zeynep; Sericano, José L; Wade, Terry L; Bianchi, Thomas S; Marcantonio, Franco; Kolker, Alexander S

2016-07-01

In 2010, an estimate 4.1 million barrels of oil were accidentally released into the Gulf of Mexico (GoM) during the Deepwater Horizon (DWH) Oil Spill. One and a half years after this incident, a set of subtidal and intertidal marsh sediment cores were collected from five stations in Barataria Bay, Louisiana, USA, and analyzed to determine the spatial and vertical distributions and source of hydrocarbon residues based on their chemical composition. An archived core, collected before the DWH oil spill from the same area, was also analyzed to assess the pre-spill hydrocarbon distribution in the area. Analyses of aliphatic hydrocarbons, polycyclic aromatic hydrocarbons (PAHs) and stable carbon isotope showed that the distribution of petroleum hydrocarbons in Barataria Bay was patchy and limited in areal extent. Significant TPH and ΣPAH concentrations (77,399 μg/g and 219,065 ng/g, respectively) were detected in the surface sediments of one core (i.e., core A) to a depth of 9 cm. Based on a sedimentation rate of 0.39 cm yr(-1), determined using (137)Cs, the presence of anthropogenic hydrocarbons in these sediment core deposited ca. 50 to 60 years ago. The historical background hydrocarbon concentrations increased significantly at the sediment surface and can be attributed to recent inputs. Although the oil present in the bay's sediments has undergone moderate weathering, biomarker analyses performed on core A samples likely indicated the presence of hydrocarbons from the DWH oil spill. The effects of oiling events on Barataria Bay and other marsh ecosystems in this region remain uncertain, as oil undergoes weathering changes over time. Copyright © 2016 Elsevier Ltd. All rights reserved.

Lead in Lake Michigan and Green Bay Surficial Sediments

EPA Science Inventory

Sediment cores were collected in 1987-1989 in Green Bay using a box corer and in 1994-1996 in Lake Michigan using a box corer and a PONAR. Core samples were segmented and dated. Historic background lead concentrations were determined for Green Bay (range=1.8-39.3 mg/kg, mean=14...

Descriptions and preliminary report on sediment cores from the southwest coastal area, Everglades National Park, Florida

USGS Publications Warehouse

Wingard, G. Lynn; Cronin, Thomas M.; Holmes, Charles W.; Willard, Debra A.; Budet, Carlos A.; Ortiz, Ruth E.

2005-01-01

Sediment cores were collected from five locations in the southwest coastal area of Everglades National Park, Florida, in May 2004 for the purpose of determining the ecosystem history of the area and the impacts of changes in flow through the Shark River Slough. An understanding of natural cycles of change prior to significant human disturbance allows land managers to set realistic performance measures and targets for salinity and other water quality and quantity quality measures. Preliminary examination of the cores indicates significant changes have taken place over the last 1000-2000 years. The cores collected from the inner bays - the most landward bays - are distinctly different from other estuarine sediment cores examined in Florida Bay and Biscayne Bay. Peats in the inner-bay cores from Big Lostmans Bay, Broad River Bay, and Tarpon Bay were deposited at least 1000 years before present (BP) based on radiocarbon analyses. The peats are overlain by poorly sorted organic muds and sands containing species indicative of deposition in a freshwater to very low salinity environment. The Alligator Bay core, the most northern inner-bay core, is almost entirely sand; no detailed faunal analyses or radiometric dating has been completed on this core. The Roberts River core, taken from the mouth of the River where it empties into Whitewater Bay, is lithologically and faunally similar to previously examined cores from Biscayne and Florida Bays; however, the basal unit was deposited ~2000 years before the present based on radiocarbon analyses. A definite trend of increasing salinity over time is seen in the Roberts River core, from sediments representing a terrestrially dominated freshwater environment at the bottom of the core to those representing an estuarine environment with a strong freshwater influence at the top. The changes seen at Roberts River could represent a combination of factors including rising sea-level and changes in freshwater supply, but the timing and extent of the changes needs to be determined. The preliminary information on the cores collected in 2004 will be combined with data from cores collected in July 2005. The 2005 cores were collected along transects moving from the inner bays out towards the coast. These transects, combining information from the 2004 and 2005 cores, will allow us to examine long term trends in freshwater supply, sea-level rise, and potentially the impact of storms on the coastal ecosystem.

Vertical distribution of trace-element concentrations and occurrence of metallurgical slag particles in accumulated bed sediments of Lake Roosevelt, Washington, September 2002

USGS Publications Warehouse

Cox, S.E.; Bell, P.R.; Lowther, J.S.; Van Metre, P.C.

2005-01-01

Sediment cores were collected from six locations in Lake Roosevelt to determine the vertical distributions of trace-element concentrations in the accumulated sediments of Lake Roosevelt. Elevated concentrations of arsenic, cadmium, copper, lead, mercury, and zinc occurred throughout much of the accumulated sediments. Concentrations varied greatly within the sediment core profiles, often covering a range of 5 to 10 fold. Trace-element concentrations typically were largest below the surficial sediments in the lower one-half of each profile, with generally decreasing concentrations from the 1964 horizon to the surface of the core. The trace-element profiles reflect changes in historical discharges of trace elements to the Columbia River by an upstream smelter. All samples analyzed exceeded clean-up guidelines adopted by the Confederated Tribes of the Colville Reservation for cadmium, lead, and zinc and more than 70 percent of the samples exceeded cleanup guidelines for mercury, arsenic, and copper. Although 100 percent of the samples exceeded sediment guidelines for cadmium, lead, and zinc, surficial concentrations of arsenic, copper, and mercury in some cores were less than the sediment-quality guidelines. With the exception of copper, the trace-element profiles of the five cores collected along the pre-reservoir Columbia River channel typically showed trends of decreasing concentrations in sediments deposited after the 1964 time horizon. The decreasing concentrations of trace elements in the upper half of cores from along the pre-reservoir Columbia River showed a pattern of decreasing concentrations similar to reductions in trace-element loading in liquid effluent from an upstream smelter. Except for arsenic, trace-element concentrations typically were smaller at downstream reservoir locations along the pre-reservoir Columbia River. Trace-element concentration in sediments from the Spokane Arm of the reservoir showed distinct differences compared to the similarities observed in cores from along the pre-reservoir Columbia River. Particles of slag, which have physical and chemical characteristics of slag discharged to the Columbia River by a lead-zinc smelter upstream of the reservoir at Trail, British Columbia, were found in sediments of Lake Roosevelt. Slag particles are more common in the upstream reaches of the reservoir. The chemical composition of the interior matrix of slag collected from Lake Roosevelt closely approximated the reported elemental concentrations of fresh smelter slag, although evidence of slag weathering was observed. Exfoliation flakes were observed on the surface of weathered slag particles isolated from the core sediments. The concentrations of zinc on the exposed surface of slag grains were smaller than concentrations on interior surfaces. Weathering rinds also were observed in the cross section of weathered slag grains, indicating that the glassy slag material was undergoing hydration and chemical weathering. Trace elements observed in accumulated sediments in the middle and lower reaches of the reservoir are more likely due to the input from liquid effluent discharges compared to slag discharges from the upstream smelter.

Distribution and depth profiles of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and polychlorinated biphenyls in sediment collected from offshore waters of Central Vietnam.

PubMed

Tri, Tran Manh; Anh, Hoang Quoc; Tham, Trinh Thi; Van Quy, Tran; Long, Nguyen Quang; Nhung, Dao Thi; Nakamura, Masafumi; Nishida, Masayo; Maeda, Yasuaki; Van Boi, Luu; Minh, Tu Binh

2016-05-15

Concentrations of PCBs and OCPs were measured in 35 surface sediment samples collected from offshore waters of Central Vietnam. The mean concentrations of PCBs, HCHs, and DDTs in surface sediments were 86.5, 37.0, and 44.5pgg(-1), respectively. Additionally, nine PCDDs, eleven PCDFs, and twelve dl-PCBs were also examined in 19 sediment core samples collected from five locations. Concentration of PCDDs, PCDFs, and dl-PCBs ranged from 200 to 460, 0.39 to 2.9, and 1.6 to 22pgg(-1), respectively. OCDD was detected at the highest concentration, ranged from 100 to 300pgg(-1). Generally, the concentrations of PCDD/Fs at shallower depths were higher, meanwhile the depth profiles of dl-PCBs in sediment cores were different than the depth profiles of PCDD/Fs. The results suggest that the pollution of PCBs might be from many different sources leading to the variation between depths. Copyright © 2016 Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gardiner, W.W.; Barrows, E.S.; Antrim, L.D

Buttermilk Channel was one of seven waterways that was sampled and evaluated for dredging and sediment disposal. Sediment samples were collected and analyses were conducted on sediment core samples. The evaluation of proposed dredged material from the channel included bulk sediment chemical analyses, chemical analyses of site water and elutriate, water column and benthic acute toxicity tests, and bioaccumulation studies. Individual sediment core samples were analyzed for grain size, moisture content, and total organic carbon. A composite sediment samples, representing the entire area proposed for dredging, was analyzed for bulk density, polynuclear aromatic hydrocarbons, and 1,4-dichlorobenzene. Site water and elutriatemore » were analyzed for metals, pesticides, and PCBs.« less

On the preservation of laminated sediments along the western margin of North America

USGS Publications Warehouse

VanGeen, A.; Zheng, Yen; Bernhard, J.M.; Cannariato, K.G.; Carriquiry, J.; Dean, W.E.; Eakins, B.W.; Ortiz, J.D.; Pike, J.

2003-01-01

Piston, gravity, and multicores as well as hydrographic data were collected along the Pacific margin of Baja California to reconstruct past variations in the intensity of the oxygen-minimum zone (OMZ). Gravity cores collected from within the OMZ north of 24??N did not contain laminated surface sediments even though bottom water oxygen (BWO) concentrations were close to 5 ??mol/kg. However, many of the cores collected south of 24??N did contain millimeter- to centimeter-scale, brown to black laminations in Holocene and older sediments but not in sediments deposited during the Last Glacial Maximum. In addition to the dark laminations, Holocene sediments in Soledad Basin, silled at 290 m, also contain white coccolith laminae that probably represent individual blooms. Two open margin cores from 430 and 700 m depth that were selected for detailed radiocarbon dating show distinct transitions from bioturbated glacial sediment to laminated Holocene sediment occurring at 12.9 and 11.5 ka, respectively. The transition is delayed and more gradual (11.3-10.0 ka) in another dated core from Soledad Basin. The observations indicate that bottom-water oxygen concentrations dropped below a threshold for the preservation of laminations at different times or that a synchronous hydrographic change left an asynchronous sedimentary imprint due to local factors. With the caveat that laminated sections should therefore not be correlated without independent age control, the pattern of older sequences of laminations along the North American western margin reported by this and previous studies suggests that multiple patterns of regional productivity and ventilation prevailed over the past 60 kyr. Copyright 2003 by the American Geophysical Union.

Pleistocene to Holocene contrasts in organic matter production and preservation on the California continental margin

USGS Publications Warehouse

Dean, W.E.; Gardner, J.V.

1998-01-01

Organic matter in sediments from cores collected from the upper continental slope (200-2700 m) off California and southern Oregon shows marked differences in concentration and marine character between the last glacial interval (ca. 24-10 ka) and either Holocene time or last interstadial (oxygen isotope stage 3, ca. 60-24 ka). In general, sediments deposited during Holocene time and stage 3 contain higher amounts of marine organic matter than those deposited during the last glacial interval, and this contrast is greatest in cores collected off southern California. The most profound differences in stage 3 sediments are between predominantly bioturbated sediments and occasional interbeds of laminated sediments. The sediments are from cores collected within the present oxygen minimum zone on the upper continental slope from as far north as the Oregon-California border to as far south as Point Conception. These upper Pleistocene laminated sediments contain more abundant hydrogen-rich (type II) marine algal organic matter than even surface sediments that have large amounts of nonrefractory organic matter. The stable carbon-isotopic composition of the organic matter does not change with time between bioturbated and laminated sediments, indicating that the greater abundance of type II organic matter in the laminated sediments is not due to a change in source but rather represents a greater degree of production and preservation of marine organic matter. The presence of abundant, well-preserved organic matter supports the theory that the oxygen minimum zone in the northeastern Pacific Ocean was more intense, and possibly anoxic, during late Pleistocene time as a result of increased coastal upwelling that enhanced algal productivity.

TEMPORAL TRENDS OF AROCLOR 1268 IN THE TAUNTON RIVER ESTUARY: EVIDENCE OF EARLY PRODUCTION, USE AND RELEASE TO THE ENVIRONMENT

EPA Science Inventory

Sediment cores were collected at three sites from the Lower Taunton River in Narragansett Bay, MA, dated and examined for PCBs. At each site, PCBs first appear in the sediment cores at depths corresponding to 1929 based on a combination of radiometric and anthropogenic dating pr...

Trace elements and organic compounds in sediment and fish tissue from the Great Salt Lake basins, Utah, Idaho, and Wyoming, 1998-99

USGS Publications Warehouse

Waddell, Kidd M.; Giddings, Elise M.

2004-01-01

A study to determine the occurrence and distribution of trace elements, organochlorine pesticides, polychlorinated biphenyls (PCBs), and semivolatile organic compounds in sediment and in fish tissue was conducted in the Great Salt Lake Basins study unit of the National Water-Quality Assessment (NAWQA) program during 1998-99. Streambed-sediment and fish-tissue samples were collected concurrently at 11 sites and analyzed for trace-element concentration. An additional four sites were sampled for streambed sediment only and one site for fish tissue only. Organic compounds were analyzed from streambed-sediment and fish-tissue samples at 15 sites concurrently.Bed-sediment cores from lakes, reservoirs, and Farmington Bay collected by the NAWQA program in 1998 and by other researchers in 1982 were used to examine historical trends in trace-element concentration and to determine anthropogenic sources of contaminants. Cores collected in 1982 from Mirror Lake, a high-mountain reference location, showed an enrichment of arsenic, cadmium, copper, lead, tin, and zinc in the surface sediments relative to the deeper sediments, indicating that enrichment likely began after about 1900. This enrichment was attributed to atmospheric deposition during the period of metal-ore mining and smelting. A core from Echo Reservoir, in the Weber River Basin, however, showed a different pattern of trace-element concentration that was attributed to a local source. This site is located downstream from the Park City mining district, which is the most likely historical source of trace elements. Cores collected in 1998 from Farmington Bay show that the concentration of lead began to increase after 1842 and peaked during the mid-1980s and has been in decline since. Recent sediments deposited during 1996-98 indicate a 41- to 62-percent reduction since the peak in the mid-1980s.The concentration of trace elements in streambed sediment was greatest at sites that have been affected by historic mining, including sites on Little Cottonwood Creek in the Jordan River basin, Silver Creek in the Weber River basin, and the Weber River below the confluence with Silver Creek. There was significant correlation of lead concentrations in streambed sediment and fish tissue, but other trace elements did not correlate well. Streambed sediment and fish tissue collected from sites in the Bear River basin, which is predominantly rangeland and agriculture, generally had low concentrations of most elements.Sediment-quality guidelines were used to assess the relative toxicity of streambed-sediment sites to aquatic communities. Sites affected by mining exceeded the Probable Effect Concentration (PEC), the concentration at which it is likely there will be a negative effect on the aquatic community, for arsenic, cadmium, copper, lead, silver, mercury, and zinc. Sites that were not affected by mining did not exceed these criteria. Concentrations of trace elements in samples collected from the Great Salt Lake Basins study unit (GRSL) are high compared to those of samples collected nationally with the NAWQA program. Nine of 15 streambed-sediment samples and 11 of 14 fish-tissue samples had concentrations of at least one trace element greater than the concentration of 90 percent of the samples collected nationally during 1993-2000.Organic compounds that were examined in streambed sediment and fish-tissue samples also were examined in bed-sediment cores. A bed-sediment core from Farmington Bay of Great Salt Lake showed an increase in total polycyclic aromatic hydrocarbon (PAH) concentrations coincident with the increase in population in Salt Lake Valley, which drains into this bay. Analysis of streambed-sediment samples showed that the highest concentrations of PAHs were detected at urban sites, including two sites in the lower Jordan River (the Jordan River flows into Farmington Bay), the Weber River at Ogden Bay, and the Provo River near Provo. Other organic compounds detected in streambed sediment in the lower Jordan River were PCBs, DDT compounds, and chlordane compounds.Organic compounds were detected more frequently in fish tissue than in streambed sediment. Chlordane compounds and PCBs were detected more frequently at urban sites. DDT compounds were detected at 13 of 15 sites including urban and agricultural sites. Concentrations of total DDT in fish tissue exceeded the guideline for protection of fish-eating wildlife at two urban sites. The concentration of organic compounds in the GRSL study unit is low compared with that of samples collected nationally.

Geoacoustic Characterization of the Mud Drape at the New England Mud Patch

NASA Astrophysics Data System (ADS)

Reed, A. H.

2016-02-01

The New England Mud Patch is an extensive deposit of fine-grained sediments that extends from an area south of Cape Cod, MA to south of Montauk Point Long Island, NY out on the continental shelf in water depths of 60 to 90 meters. The mud patch has a remarkable accumulation of up to a 13 meter thick sequence of mud that overlays a transgressive surface of Pleistocene Age and then thins out on the periphery where surficial sediments convert from mud to sand and sand/gravel. The deposit likely accumulated in this region due to the coalescing of shelf currents that had oppositional flow. This work focuses on a section of the mud patch that is centered over the thickest portion of mud and extends east-west for 30 km and north south for 10 km. Gravity cores were collected throughout this region and the cores penetrated the upper 2-4 m of mud at 28 different sites with multiple cores collected in several locations. The mud thickness in these regions exceeded the core barrel length, therefore the cores did not penetrate into the basal sand sediment layer, a relict transgressional horizon, which displays prominently in the acoustic data for this selected region. These cores were evaluated for compressional sound speed (averaging 1480 m/s) and density (1580 kg/m3) and found to be largely homogeneous and similar throughout the study area. The largest source of inhomogeneity was due to dispersed shell hash and disarticulated bivalves, but these inclusions represent minor components in the total sediment volume. The overlying sediment that characterizes the New England Mud Patch can be readily classified as mud, silty mud, or sandy-silty mud. This fine-grained sediment deposit reflects upon the low-energy nature of the hydrodynamics within this region.

Sediment Core Extrusion Method at Millimeter Resolution Using a Calibrated, Threaded-rod.

PubMed

Schwing, Patrick T; Romero, Isabel C; Larson, Rebekka A; O'Malley, Bryan J; Fridrik, Erika E; Goddard, Ethan A; Brooks, Gregg R; Hastings, David W; Rosenheim, Brad E; Hollander, David J; Grant, Guy; Mulhollan, Jim

2016-08-17

Aquatic sediment core subsampling is commonly performed at cm or half-cm resolution. Depending on the sedimentation rate and depositional environment, this resolution provides records at the annual to decadal scale, at best. An extrusion method, using a calibrated, threaded-rod is presented here, which allows for millimeter-scale subsampling of aquatic sediment cores of varying diameters. Millimeter scale subsampling allows for sub-annual to monthly analysis of the sedimentary record, an order of magnitude higher than typical sampling schemes. The extruder consists of a 2 m aluminum frame and base, two core tube clamps, a threaded-rod, and a 1 m piston. The sediment core is placed above the piston and clamped to the frame. An acrylic sampling collar is affixed to the upper 5 cm of the core tube and provides a platform from which to extract sub-samples. The piston is rotated around the threaded-rod at calibrated intervals and gently pushes the sediment out the top of the core tube. The sediment is then isolated into the sampling collar and placed into an appropriate sampling vessel (e.g., jar or bag). This method also preserves the unconsolidated samples (i.e., high pore water content) at the surface, providing a consistent sampling volume. This mm scale extrusion method was applied to cores collected in the northern Gulf of Mexico following the Deepwater Horizon submarine oil release. Evidence suggests that it is necessary to sample at the mm scale to fully characterize events that occur on the monthly time-scale for continental slope sediments.

Sediment Core Extrusion Method at Millimeter Resolution Using a Calibrated, Threaded-rod

PubMed Central

Schwing, Patrick T.; Romero, Isabel C.; Larson, Rebekka A.; O'Malley, Bryan J.; Fridrik, Erika E.; Goddard, Ethan A.; Brooks, Gregg R.; Hastings, David W.; Rosenheim, Brad E.; Hollander, David J.; Grant, Guy; Mulhollan, Jim

2016-01-01

Aquatic sediment core subsampling is commonly performed at cm or half-cm resolution. Depending on the sedimentation rate and depositional environment, this resolution provides records at the annual to decadal scale, at best. An extrusion method, using a calibrated, threaded-rod is presented here, which allows for millimeter-scale subsampling of aquatic sediment cores of varying diameters. Millimeter scale subsampling allows for sub-annual to monthly analysis of the sedimentary record, an order of magnitude higher than typical sampling schemes. The extruder consists of a 2 m aluminum frame and base, two core tube clamps, a threaded-rod, and a 1 m piston. The sediment core is placed above the piston and clamped to the frame. An acrylic sampling collar is affixed to the upper 5 cm of the core tube and provides a platform from which to extract sub-samples. The piston is rotated around the threaded-rod at calibrated intervals and gently pushes the sediment out the top of the core tube. The sediment is then isolated into the sampling collar and placed into an appropriate sampling vessel (e.g., jar or bag). This method also preserves the unconsolidated samples (i.e., high pore water content) at the surface, providing a consistent sampling volume. This mm scale extrusion method was applied to cores collected in the northern Gulf of Mexico following the Deepwater Horizon submarine oil release. Evidence suggests that it is necessary to sample at the mm scale to fully characterize events that occur on the monthly time-scale for continental slope sediments. PMID:27585268

Sedimentation of the mud belt along the coast of China from the mouth of the Yangtze (Changjiang) River to northern Taiwan Strait: An Source-to-Sink Perspective

NASA Astrophysics Data System (ADS)

Chien, C. C.; Liu, J. T.; Yang, R.; Huh, C. A.; Su, C. C.

2016-02-01

Sediments in the Taiwan Strait are originated from Mainland China and Taiwan. The China Coastal Current, influenced by the northeast monsoon in winter, becomes enhanced, which caries the sediments exported from the Yangtze River to the southern East China Sea and the Taiwan Strait along the Zhemin-Taiwan Strait mud belt. The sediment transport process is also influenced by tidal current and Kuroshio Branch Current and Taiwan Warm Current, making the seafloor sediment signals complex. This study used R/V Ocean Researcher V (Cruise 0032), to collect six box cores and three gravity cores along the Zhemin mud belt and the mud belt in northern Taiwan Strait in the winter of 2014. From the core samples, grain-size distribution, Multi-Sensor Core Logger, and 7Be activity were measured to investigate the sedimentation process along the mud belts. The box core taken at the mouth of the Changjiang- is composed of homogeneous clay and rich in shell fragments. The core off the mouth of Ou River is composed of homogeneous clay, but showing horizontal laminations. Near the Taishan Island off the coast of Zhejiang the core is consisted of a homogeneous sandy sediments that turned into clay. Off the mouth of the Min River the core consists of clay with shell fragments. Off the coast of the Wu River on the west coast of the Taiwan, the core is mainly composed of muddy sediments, which has the siltstone layers of oblique bedding. Off the mouth of Zhuoshui River in central Taiwan, the core is composed of sandy sediments. From the mouth of the Changhjiang, Zhemin mud belt, the northern Taiwan Strait mud belt, to the central Taiwan Strait, 7Be activity in the seafloor sediment indicates that the freshness of the terrigenous sediments decreased. The Mass Magnetic Susceptiblity (MSI) demonstrates that the terrigenous sediments decreased from north to south. The MSI signals in the core off the mouth of the Minjiang are different from those in the neighboring cores. This is suspected due to the convergence of sediments from the Changjiang and Taiwan. The particle sizes of the cores show that the sediment became coarser from the north to south. In the future the study will make use of 210Pbex, and other environmental and provenance such as water dynamic mechanism variables to explore the sediment source and sink patterns along with the Zhemin-Taiwan Strait mud belts.

Short Term Sediment Exchange Between Marshes and Bays Using Beryllium-7 as a Tracer, Fourleague Bay, Louisiana.

NASA Astrophysics Data System (ADS)

Restreppo, G. A.; Bentley, S. J.; Xu, K.; Wang, J.

2016-12-01

Modern delta models focus on the availability and exchange of coarse sediment as one of the major factors of deltaic growth or decay. Fine-grained sediment exchange within a river's delta is relatively poorly understood, as is the impact that this exchange has on land building and land loss. To better understand the dynamics of fine grain sediment exchange between river mouth, adjacent bays, and marshland, sediment cores from Fourleague Bay, LA, were collected and analyzed for 7Be, a naturally occurring radioisotope that serves as a marker for recently deposited sediment. Time-series push cores were collected every two months at ten sites, five located across a longitudinal transect in the middle bay and five located along adjacent marshes, from May 2015 to May 2016. All sites fall within 11 to 28 km of the Atchafalaya Delta, along a gradient extending towards the open ocean. Cores were extruded in 2 cm intervals, dried, ground, and analyzed via gamma spectrometry for the presence of 7Be. Inventories of 7Be were then calculated and used to determine bimonthly sedimentation rates over the course twelve months. Sediment deposition on the bay floor and marsh surface were then compared to Atchafalaya River discharge, wind speed and direction, and wave action. Preliminary results indicate patterns of initial fluvial sediment transfer from river to bay floor, then bay floor to marsh surface, with decreasing fluvial influence towards the open ocean. Sediment transport from bay to marsh appears to be coupled with meteorological forcing that induces bay-floor sediment resuspension and the flooding of marsh surfaces. This indirect mechanism of fluvial sediment supply to wetland surfaces may extend the region of influence for sediment delivery from man-made river-sediment diversions.

Selected data for sediment cores collected in Chesapeake Bay in 1996 and 1998

USGS Publications Warehouse

Baucom, P.C.; Bratton, J.F.; Colman, Steven M.; Moore, Johnnie N.; King, John W.; Seal, Chip; Seal, R.R.

2001-01-01

As part of a study of recent history of the Chesapeake Bay ecosystem, one- to eight- meter long sediment cores were obtained from the mesohaline section of the Chesapeake Bay between the mouths of the Potomac and Rhode Rivers. The sediments consist of three lithofacies: coarse-grained channel deposits, restricted-estuary sands and muds, and open-estuary muds. Water content, biogenic silica, magnetic susceptibility, trace metals, and nutrients (carbon, nitrogen, and their isotopes) were measured in the cores. Biogenic silica, trace-metal, and nutrient data provide a strong basis for discussing past primary productivity and water-column anoxia in the bay.

Assessing Sedimentation Issues Within Aging Flood Control Reservoirs in Oklahoma

NASA Astrophysics Data System (ADS)

Bennet, Sean J.; Cooper, Charles M.; Ritchie, Jerry C.; Dunbar, John A.; Allen, Peter M.; Caldwell, Larry W.; McGee, Thomas M.

2002-10-01

Since 1948, the USDA-NRCS has constructed nearly 11,000 flood control dams across the United States, and many of the reservoirs are rapidly filling with sediment. To rehabilitate these structures, the impounded sediment must be assessed to determine the volume of accumulated sediment and the potential hazard this sediment may pose if reintroduced to the environment. An assessment of sedimentation issues within two reservoirs, Sugar Creek No. 12, Hinton, Oklahoma, and Sergeant Major No. 4, Cheyenne, Oklahoma, is presented. Sediment cores obtained using a vibracoring system were composed of alternating layers of gravel, sand, silt, and clay. Stratigraphic analysis coupled with 137Cs dating techniques enabled the discrimination of pre-construction sediment from post-construction deposition. An acoustic profiling system was unencumbered by the relatively shallow water depth at Sugar Creek No. 12 and the seismic horizons agreed well with the sediment core data. Total sediment volume determined from the acoustic survey and the sediment core data for comparable areas differed by only 1.4 percent. The seismic profiling system worked well in the relatively deeper lake of Sergeant Major No. 4 and showed good correspondence to the collected core data. Detailed chemical analyses showed that overall sediment quality was good at both locations and that chemical composition was spatially invariant. Implementation of these techniques will aid action agencies such as the USDA-NRCS in their assessment and effective management of aging flood control reservoirs.

Identifying sediment discontinuities and solving dating puzzles using monitoring and palaeolimnological records

NASA Astrophysics Data System (ADS)

Dong, Xuhui; Sayer, Carl D.; Bennion, Helen; Maberly, Stephen C.; Yang, Handong; Battarbee, Richard W.

2016-12-01

Palaeolimnological studies should ideally be based upon continuous, undisturbed sediment sequences with reliable chronologies. However for some lake cores, these conditions are not met and palaeolimnologists are often faced with dating puzzles caused by sediment disturbances in the past. This study chooses Esthwaite Water from England to illustrate how to identify sedimentation discontinuities in lake cores and how chronologies can be established for imperfect cores by correlation of key sediment signatures in parallel core records and with long-term monitoring data (1945-2003). Replicated short cores (ESTH1, ESTH7, and ESTH8) were collected and subjected to loss-on-ignition, radiometric dating (210Pb, 137Cs, and 14C), particle size, trace metal, and fossil diatom analysis. Both a slumping and a hiatus event were detected in ESTH7 based on comparisons made between the cores and the long-term diatom data. Ordination analysis suggested that the slumped material in ESTH7 originated from sediment deposited around 1805-1880 AD. Further, it was inferred that the hiatus resulted in a loss of sediment deposited from 1870 to 1970 AD. Given the existence of three superior 14C dates in ESTH7, ESTH1 and ESTH7 were temporally correlated by multiple palaeolimnological proxies for age-depth model development. High variability in sedimentation rates was evident, but good agreement across the various palaeolimnological proxies indicated coherence in sediment processes within the coring area. Differences in sedimentation rates most likely resulted from the natural morphology of the lake basin. Our study suggests that caution is required in selecting suitable coring sites for palaeolimnological studies of small, relatively deep lakes and that proximity to steep slopes should be avoided wherever possible. Nevertheless, in some cases, comparisons between a range of contemporary and palaeolimnological records can be employed to diagnose sediment disturbances and establish a chronology.

Late Holocene sedimentary environments of south San Francisco Bay, California, illustrated in gravity cores

USGS Publications Warehouse

Woodrow, Donald L.; Fregoso, Theresa A.; Wong, Florence L.; Jaffe, Bruce E.

2014-01-01

Data are reported here from 51 gravity cores collected from the southern part of San Francisco Bay by the U.S. Geological Survey in 1990. The sedimentary record in the cores demonstrates a stable geographic distribution of facies and spans a few thousand years. Carbon-14 dating of the sediments suggests that sedimentation rates average about 1 mm/yr. The geometry of the bay floor and the character of the sediment deposited have remained about the same in the time spanned by the cores. However, the sedimentary record over periods of centuries or decades is likely to be much more variable. Sediments containing a few bivalve shells and bivalve or oyster coquinas are most often found west of the main channel and near the San Mateo Bridge. Elsewhere in the south bay, shells are rare except in the southernmost reaches where scattered gastropod shells are found.

Pore Water Transport of Enterococci out of Beach Sediments

PubMed Central

Phillips, Matthew C.; Solo-Gabriele, Helena M.; Reniers, Adrianus J. H. M.; Wang, John D.; Kiger, Russell T.; Abdel-Mottaleb, Noha

2011-01-01

Enterococci are used to evaluate the safety of beach waters and studies have identified beach sands as a source of these bacteria. In order to study and quantify the release of microbes from beach sediments, flow column systems were built to evaluate flow of pore water out of beach sediments. Results show a peak in enterococci (average of 10% of the total microbes in core) released from the sand core within one pore water volume followed by a marked decline to below detection. These results indicate that few enterococci are easily removed and that factors other than simple pore water flow control the release of the majority of enterococci within beach sediments. A significantly larger quantity and release of enterococci were observed in cores collected after a significant rain event suggesting the influx of fresh water can alter the release pattern as compared to cores with no antecedent rainfall. PMID:21945015

Lead contamination and source in Shanghai in the past century using dated sediment cores from urban park lakes.

PubMed

Li, H B; Yu, S; Li, G L; Deng, H

2012-08-01

Lead contamination becomes of importance to urban resident health worldwide, especially for child health and growth. Undisturbed lake sediment cores are increasingly employed as a useful tool to backdate environmental contamination history. Five intact sediment cores collected from lakes in five urban parks were dated using (210)Pb and analyzed for total Pb content and isotope ratio to reconstruct the Pb contamination history over the last century in Shanghai, China. Total Pb content in the sediment cores increased by about 2- to 3-fold since 1900s. The profile of Pb flux in each sediment core revealed a remarkable increase of Pb contamination in Shanghai over the past century, especially in the latest three decades when China was experiencing a rapid economic and industrial development. Significant correlations were found between Pb fluxes in sediment cores and Pb emission from coal combustion in Shanghai. Coal combustion emission dominated anthropogenic Pb sources during the past century contributing from 52% to 69% of total Pb in cores, estimated by a three-end member model of Pb isotope ratios. Leaded gasoline emission generally contributed <30% of total Pb, which was banned by 1997 in the Shanghai region. Our results implicate that coal combustion-based energy consumption should be replaced, or at least partially replaced, to reduce health risks of Pb contamination in Shanghai. Copyright © 2012 Elsevier Ltd. All rights reserved.

Shallow stratigraphy of the Skagit River Delta, Washington, derived from sediment cores

USGS Publications Warehouse

Grossman, Eric E.; George, Douglas A.; Lam, Angela

2011-01-01

Sedimentologic analyses of 21 sediment cores, ranging from 0.4 to 9.6 m in length, reveal that the shallow geologic framework of the Skagit River Delta, western Washington, United States, has changed significantly since 1850. The cores collected from elevations of 3.94 to -2.41 m (relative to mean lower low water) along four cross-shore transects between the emergent marsh and delta front show relatively similar environmental changes across an area spanning ~75 km2. Offshore of the present North Fork Skagit River and South Fork Skagit River mouths where river discharge is focused by diked channels through the delta, the entire 5–7-km-wide tidal flats are covered with 1–2 m of cross-bedded medium-to-coarse sands. The bottoms of cores, collected in these areas are composed of mud. A sharp transition from mud to a cross-bedded sand unit indicates that the tidal flats changed abruptly from a calm environment to an energetic one. This is in stark contrast to the Martha's Bay tidal flats north of the Skagit Bay jetty that was completed in the 1940s to protect the newly constructed Swinomish Channel from flooding and sedimentation. North of the jetty, mud ranging from 1 to 2 m thick drapes a previously silt- and sand-rich tidal flat. The silty sand is a sediment facies that would be expected there where North Fork Skagit River sedimentation occurred prior to jetty emplacement. This report describes the compositional and textural properties of the sediment cores by using geophysical, photographic, x-radiography, and standard sediment grain-size and carbon-analytical methods. The findings help to characterize benthic habitat structure and sediment transport processes and the environmental changes that have occurred across the nearshore of the Skagit River Delta. The findings will be useful for quantifying changes to nearshore marine resources, including impacts resulting from diking, river-delta channelization, shoreline development, and natural variations in fluvial-sediment inputs. These results also provide important quantitative data on the amount of sediment delivered to the nearshore from the Skagit River for use in calculating sediment budgets for application to watershed planning and wetland and coastal-ecosystem restoration.

Paleoenvironmental reconstruction of lagoonal strata from Sri Lanka using multiple physical properties proxies to assure stratigraphic continuity

NASA Astrophysics Data System (ADS)

Ranasinghage, P. N.; Ortiz, J. D.; Moore, A.; Siriwardana, C.

2009-12-01

Core collapsing is a common problem in studies of lagoonal sediment cores. Coring liquefied sediments below the water table can lead to collapse of material from upper core drives in to the hole. This can be prevented by casing the hole. But casing is not always possible due to practical issues such as coring device type, resources, or time constraints. In such cases identifying the collapsed material in each drive is necessary to ensure accurate results. Direct visual identification of collapsed portion is not always possible and may not be precise. This study successfully recognized collapsed material using a suite of physical properties measurements including: visible (VIS) reflectance spectroscopy, magnetic susceptibility and grain size spectra. This enables us to use the verified stratigraphically continuous records for paleo-environmental studies. Sediment cores were collected from three coastal lagoons and a swale along south eastern and eastern Sri Lanka. Cores were collected using a customized AMS soil coring device with a 1-m long sample barrel. The metal barrel of this instrument collects a 2.5 cm diameter sample in 1-m long plastic tubes. Coring was conducted to refusal, with a maximum depth of 5 m. Casing was not applied to the holes due to small core diameter and time constrains. Drill holes were placed at locations situated both below and above the water level of the lagoons. A total of 100 m of sediment core were obtained from these locations. After opening the cores, suspected collapsed material was initially identified by visual observation using a high power binocular microscope. Particle size, magnetic susceptibility, X-ray fluorescence (XRF) and Diffuse Spectral Reflectance (DSR) was then measured on all cores at 1-2 cm resolution to precisely define the repeated sediment intervals. Down core variation plots of magnetic susceptibility, CIE L* (lightness), a*(red/green difference), b* (blue and yellow difference) clearly record abrupt changes at core drive boundaries at the presence of collapsed material. The correlation of grain-size spectra from the bottom and top of consecutive drives was used to precisely determine the thickness of the collapsed material between drives. Our analysis of 48 m of core material thus far indicates that ~4.4m or ~9% of the record represents collapsed material which can be excluded from further study. The remaining continuous record was analyzed for paleoenvironmental studies. Down core variation of grain size, geochemical ratios, principle components of DSR and geochemical data, and magnetic susceptibility from all locations indicate a gradual filling of these deep lagoons and a transition from reducing to oxic conditions. According to an age model constructed for a nearby lagoon the onset of regression began ~6,000 years BP. Several instantaneous sedimentation events were recorded in all lagoons. Further studies will be carried out to determine whether these represent tsunami, storm surge, or flood deposits.

Natural thorium isotopes in marine sediment core off Labuan port

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hafidz, B. Y.; Asnor, A. S.; Terence, R. C.

2014-02-12

Sediment core was collected from Labuan port and analyzed to determine the radioactivity of thorium (Th) isotopes. The objectives of this study are to determine the possible sources of Th isotopes at Labuan port and estimates the sedimentation rate based on {sup 228}Th/{sup 232}Th model. The results suggest the {sup 230}Th and {sup 232}Th might be originated from terrestrial sedimentary rock while {sup 228}Th originated by authigenic origin. High ratio value of {sup 230}Th/{sup 232}Th detected at the top surface sediment indicates the increasing of {sup 230}Th at the recent years which might be contributed from the anthropogenic sources. Themore » sedimentation rate of core sediment from Labuan Port was successfully estimated by using {sup 228}Th/{sup 232}Th model. The result show high sedimentation rate with 4.67 cm/year indicates rapid deposition occurred at this study area due to the high physical activity at the Labuan port. By assume the constant sedimentation rate at this area; we estimated the age of 142 cm core sediment obtained from Labuan port is 32 years started from 1981 to 2012. This chronology will be used in forthcoming research to investigate the historical profile of anthropogenic activities affecting the Labuan port.« less

Quaternary Turbidite Sedimentation in the Moresby Trough, Preliminary Observations from the Papua New Guinea S2S Study Area

NASA Astrophysics Data System (ADS)

Bentley, S. J.; Muhammad, Z.; Dickens, J.; Droxler, A.; Peterson, L.; Opdyke, B.

2004-12-01

Multicores and jumbo piston cores were collected from the Moresby Trough from the R/V Melville in March-April 204 to study patterns of off-shelf sediment flux from the Gulf of Papua to the deep sea over Pleistocene-Holocene timescales. The Moresby Trough represents the primary deep-sea sediment conduit linking the Source to Sink Gulf of Papua study area to the north with the Coral Sea Basin to the south. Core locations were navigated from the surface using dynamic positioning and multibeam bathymetric mosaics collected during the cruise. Selected cores have been analyzed using a multi-sensor core logger, X-radiography, granulometry, and Pb-210 geochronology. Most piston cores collected from the Moresby Trough contain abundant mafic sandy turbidites overlain by fine-grained hemipelagic deposits 1-2 m thick. X-radiographs of multicores reveal mostly bioturbated hemipelagics. However, one core, MV25-0403-24MC, was collected from the axis of a primary channel, and contains at least two fine-grained turbidites within the upper 0.5 m of sediment. The uppermost turbidite contains low but uniform activities of excess Pb-210, and may have been 15-20 cm thick at the time of deposition (i.e., before subsequent disruption by bioturbation), based on fabric and radiochemical evidence. Application of a simple box-model for physical mixing (i.e., during the flow) and subsequent decay suggests that the uppermost turbidite was deposited 70-120 years before present. Bioturbation has since reworked about 60% of the bed, suggesting that such beds will only escape destruction by bioturbation if they are > 10 cm thick, and are deposited more frequently than once per century. Based on these observations, we suggest that gravity flows are presently active in the Moresby trough, and may account for a significant fraction of the hemipelagic drape present in channel systems. However, fabric evidence for these thin, fine-grained beds may be obscured by subsequent bioturbation. Also, at some point in the past, possibly at the onset of the Holocene Transgression, the character of sediment flux to the Moresby Trough shifted from sandy mafic-rich sandy turbidity currents to much finer sediments, delivered downslope by both benthic flows and vertical flux through the water column.

Sedimentary properties of shallow marine cores collected in June and September 2006, Hanalei Bay, Kaua‘i, Hawai‘i

USGS Publications Warehouse

Draut, Amy E.; Bothner, Michael H.; Reynolds, Richard L.; Buchan, Olivia C.; Cochran, Susan A.; Casso, Michael A.; Baldwin, Sandra M.; Goldstein, Harland L.; Xiao, Jiang; Field, Michael E.; Logan, Joshua B.

2007-01-01

Sedimentary facies, short-lived isotopes 7Be, 137Cs, and 210Pb, and magnetic properties of sediment cores in Hanalei Bay, Kaua‘i, Hawai‘i, were used to assess sediment sources and patterns of deposition associated with seasonal flooding of the Hanalei River. Sediment cores were collected from the seafloor in June and September of 2006 to supplement similar data collected during the summer of 2005. The youngest and thickest terrigenous sediment was observed on the east side of the bay: near the Hanalei River mouth and in a bathymetric depression, known locally as the Black Hole, that acts as a temporary sediment sink. Deposits from floods that occurred between February and April 2006 left flood deposits in the eastern bay that, by June of 2006, were on the order of 10 cm thick. A flood occurred on August 7, 2006, that was smaller than floods that occurred the previous winter but was a substantial discharge event for the summer season. Deposits from the winter 2006 floods continued to dominate the sedimentary record in the eastern bay through early fall, even after the addition of newer sediment during the August 7 flood; this is consistent with the much higher sediment input of the winter floods compared with the August 7 flood. Broad variations in magnetic grain size and relative magnetite-hematite abundance in several sediment cores indicate many sources of upland terrigenous sediment. As a group, recent flood deposits show much less variation in these properties compared with older deposits, implying either that the 2006 winter–spring flood sediment originated from one or more distinct upland settings, or that substantial mixing of sediment from multiple sources occurred during transport. Sediment is most readily remobilized and advected out of the bay during winter, when oceanic conditions are energetic. In summer, wave and current measurements made concurrently with this study showed weak currents and little wave energy, indicating that sediment delivered during summer floods most likely remains in the bay until winter storms can remove it. Increased turbidity and sedimentation on corals resulting from floods of the Hanalei River could affect the sustainability of coral reefs and their many associated species. This possibility is of particular concern during summer months when wave energy is low and sediment is not readily remobilized and transported out of the bay. The timing (seasonality) and magnitude of sediment input to the coastal ocean relative to seasonal variations in wave and current energy could have significant ecological consequences for coral-reef communities in the Hawaiian Islands.

LONG-TERM RECOVERY OF PCB-CONTAMINATED SEDIMENTS AT THE LAKE HARTWELL SUPERFUND SITE: PCB DECHLORINATION. 2. RATES AND EXTENT

EPA Science Inventory

This paper reports on extensive polychlorinated biphenyl (PCB) dechlorination measured in Lake Hartwell (Pickens County, SC) sediments. Vertical sediment cores were collected from 18 locations in Lake Hartwell (Pickens County, SC) and analyzed in 5-cm increments for PCB congeners...

Mineralogy of Gas Hydrate Bearing Sediment in Green Canyon Block 955 Northern Gulf of Mexico

NASA Astrophysics Data System (ADS)

Heber, R.; Kinash, N.; Cook, A.; Sawyer, D.; Sheets, J.; Johnson, J. E.

2017-12-01

Natural gas hydrates are of interest as a future hydrocarbon source, however, the formation and physical properties of such systems are not fully understood. In May 2017, the University of Texas drilled two holes in Green Canyon Block 955, northern Gulf of Mexico to collect pressurized core from a thick, 100 m accumulation of gas hydrate in a silt dominated submarine canyon levee system. The expedition, known as UT-GOM2-01, collected 21, 10-m pressure cores from Holes H002 and H005. Approximately half of the cores successfully pressurized and were fully recovered. Unsuccessful cores that did not pressurize generally had low core recovery. By analyzing the sediment composition in known gas hydrate reservoirs, we can construct a more detailed picture of how and why gas hydrates accumulate, as mineralogy can affect physical properties such as porosity and permeability as well as geophysical measurements such as resistivity. Using X-ray diffraction (XRD) on bulk sediment powders, we determined the bulk mineralogy of the samples. Moreover, we investigated drilling mud contamination using XRD and light optical analysis. In some cores, contamination was easily recognized visually as dense sludge between the core barrel and the recovered sediment core, however drilling mud is best observed both along the liner and interbedded within the sediment on X-ray computed tomography scans. To fully identify the presence and influence of drilling mud, we use XRD to analyze samples on cores collected both while drilling mud was used in hole and when only seawater was used in hole and consider the density anomalies observed on the XCT scans. The preliminary XRD light optical microscopy results show that the silt-dominated reservoir is primarily composed of quartz, with minor alkali feldspar, amphibole, muscovite, dolomite, and calcite. Samples from intervals with suspected drilling mud contamination show a similar composition, but with the addition of barite, a common component in drilling mud. Understanding why contamination occurs will improve the coring process and ensure maximum recovery in the future. The XRD data also show the presence of 7-angstrom clay minerals, most likely chlorite and serpentine, but more analysis is required in order to verify the identification and to establish relative abundances of each mineral.

Multivariate analysis of heavy metal contamination using river sediment cores of Nankan River, northern Taiwan

NASA Astrophysics Data System (ADS)

Lee, An-Sheng; Lu, Wei-Li; Huang, Jyh-Jaan; Chang, Queenie; Wei, Kuo-Yen; Lin, Chin-Jung; Liou, Sofia Ya Hsuan

2016-04-01

Through the geology and climate characteristic in Taiwan, generally rivers carry a lot of suspended particles. After these particles settled, they become sediments which are good sorbent for heavy metals in river system. Consequently, sediments can be found recording contamination footprint at low flow energy region, such as estuary. Seven sediment cores were collected along Nankan River, northern Taiwan, which is seriously contaminated by factory, household and agriculture input. Physico-chemical properties of these cores were derived from Itrax-XRF Core Scanner and grain size analysis. In order to interpret these complex data matrices, the multivariate statistical techniques (cluster analysis, factor analysis and discriminant analysis) were introduced to this study. Through the statistical determination, the result indicates four types of sediment. One of them represents contamination event which shows high concentration of Cu, Zn, Pb, Ni and Fe, and low concentration of Si and Zr. Furthermore, three possible contamination sources of this type of sediment were revealed by Factor Analysis. The combination of sediment analysis and multivariate statistical techniques used provides new insights into the contamination depositional history of Nankan River and could be similarly applied to other river systems to determine the scale of anthropogenic contamination.

Facies-dependent variations in sediment physical properties on the Mississippi River Delta Front, USA: evidence for depositional and post-depositional processes

NASA Astrophysics Data System (ADS)

Smith, J. E., IV; Bentley, S. J.; Courtois, A. J.; Obelcz, J.; Chaytor, J. D.; Maloney, J. M.; Georgiou, I. Y.; Xu, K.; Miner, M. D.

2017-12-01

Recent studies on Mississippi River Delta have documented sub-aerial land loss, driven in part by declining sediment load over the past century. Impacts of changing sediment load on the subaqueous delta are less well known. The subaqueous Mississippi River Delta Front is known to be shaped by extensive submarine mudflows operating at a range of temporal and spatial scales, however impacts of changing sediment delivery on mudflow deposits have not been investigated. To better understand seabed morphology and stratigraphy as impacted by plume sedimentation and mudflows, an integrated geological/geophysical study was undertaken in delta front regions offshore the three main passes of the Mississippi River Delta. This study focuses on stratigraphy and physical properties of 30 piston cores (5-9 m length) collected in June 2017. Coring locations were selected in gully, lobe and prodelta settings based on multibeam bathymetry and seismic profiles collected in mid-May 2017. Cores were analyzed for density, magnetic susceptibility, P-wave speed, and resistivity using a Geotek multi sensor core logger; here, we focus on density data. Core density profiles generally vary systematically across facies. Density profiles of gully cores are nearly invariant with some downward stepwise increases delineating units meters thick, and abundant gaps likely caused by gas expansion. Lobe cores generally have subtle downward increases in density, some stepwise density increases, and fewer gaps. Prodelta cores show more pronounced downward density increases, decimeter-scale peaks and valleys in density profiles, but stepwise increases are less evident. We hypothesize that density profiles in gully and lobe settings (uniform profiles except for stepwise increases) reflect remolding by mudflows, whereas density variations in prodelta settings instead reflect grain size variations (decimeter-scale) and more advanced consolidation (overall downward density increase) consistent with slower sediment deposition. These hypotheses will be evaluated by a more detailed study of seismic stratigraphy and core properties, including geochronology, grain size distribution and X-radiographic imaging, to further relate important sedimentary processes with resulting deposits.

Evaluation of dredged material proposed for ocean disposal from Gravesend Bay Anchorage, New York

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barrows, E.S.; Gruendell, B.D.

1996-09-01

The Gravesend Bay Anchorage was one of seven waterways that the US Army Corps of Engineers-New York District (USACE-NYD) requested the Battelle Marine Sciences Laboratory (MSL) to sample and evaluate for dredging and disposal in February 1994. Sediment samples were submitted for physical and chemical analyses to provide baseline sediment chemistry data on the Gravesend Bay Anchorage. Individual sediment core samples collected at the Gravesend Bay Anchorage were analyzed for grain size, moisture content, and total organic carbon (TOC). Two samples, one of composited sediment cores representing the southeast corner of the anchorage (COMP GR), and one sediment core representingmore » the northeast corner of the anchorage (Station GR-1 0), were analyzed for bulk density, specific gravity, metals, chlorinated pesticides, polychlorinated biphenyl (PCB) congeners, polynuclear aromatic hydrocarbons (PAH), and 1,4-dichlorobenzene.« less

Organic Geochemistry of Sediments in Nearshore Areas of the Mississippi and Atchafalaya Rivers: I. General Organic Characterization

USGS Publications Warehouse

Orem, William H.; Rosenbauer, Robert J.; Swarzenski, Peter W.; Lerch, Harry E.; Corum, Margo D.; Bates, Anne L.

2007-01-01

This report presents results on the general organic characteristics of sediment cores collected from the coastal zone of the Mississippi River system, including distributions of the important nutrient elements (C, N, P, and S). This was part of a larger study conducted from 2001-2005 to examine the delivery of sediment-associated contaminants to the Gulf of Mexico by the Mississippi River system, funded by the USGS Coastal and Marine Geology Program. Companion reports emphasize organic contaminants (Rosenbauer and others, 2006), and metals (Swarzenski and others, 2006). The level of contamination within the deltaic system of the Mississippi River system was determined through the collection of sediment cores from interdistributary bays, and offshore in the Gulf of Mexico, including the zone of hypoxia. Results provide the basis for reconstructing contaminant inventories from which to develop historic perspectives on nutrient loading and hypoxia, and to better understand how sediment-hosted contaminants either directly or indirectly move through biota and ultimately affect ecosystem health. Concentrations of C, N, P, and S in sediments varied by a factor of 10 between sites, and in down core profiles. Nearshore cores collected in 2001 proved to have erratic downcore C, N, P, and S profiles and sediment deposition rates, suggesting a high energy regime controlled more by variability in river flow rather than by geochemical processes and reactions within the system. These results focused further coring activities further offshore. Atomic C/N ratios suggest that organic matter deposited at all sites is a mix of microbial (algal) and terrestrial (vascular plant) remains, but with algal material dominant. Concentrations of total sulfur in sediments from cores in the zone of hypoxia were often higher than those in nearby zones with oxic water columns. Corresponding atomic C/S ratios were typically lower in sediments from sites in the zone of hypoxia compared to nearby sites with oxic water columns, and thus atomic C/S values may be useful as a proxy for identifying sites impacted by hypoxic conditions in the water column and for examining historical trends in hypoxia. At one site examined in this study, maximum hypoxic conditions were observed in the mid 1960's. The organic elemental composition (C, N, P, and S) of sediments was also used to guide sample selection for contaminant analysis, and to normalize the contaminant data to organic C content of the sediments. Dissolved hydrocarbon gases in sediments showed a dominance of methane, but identifiable concentrations of ethane and hexane, and trace concentrations of propane, butane, and pentane were also detected. All dissolved gases except hexane were dominated by 'bound' gas, gas released only after agitation of the sediment in a blender. Hexane, in contrast was observed mostly as free gas, determined by headspace analysis.

Summary of Results from Analyses of Deposits of the Deep-Ocean Impact of the Eltanin Asteroid

NASA Technical Reports Server (NTRS)

Kyte, Frank T.; Kuhn, Gerhard; Gersonde, Rainer

2005-01-01

Deposits of the late Pliocene (2.5 Ma) Eltanin impact are unique in the known geological record. The only known example of a km-sized asteroid to impact a deep-ocean (5 km) basin, is the most meterorite-rich locality known. This was discovered as an Ir anomaly in sediments from three cores collected in 1965 by the USNS Eltanin. These cores contained mm-sized shock-melted asteroid materials and unmelted meteorite fragments. Mineral chemistry of meteorite fragments, and siderophole concentrations in melt rocks, indicate that the parent asteroid was a low-metal (4\\%) mesosiderite. A geological exploration of the impact in 1995 by Polarstern expedition ANT-XIV4 was near the Freeden Seamounts (57.3S, 90.5 W), and successfully collected three cores with impact deposits. Analyses showed that sediments as old as Eocene were eroded by the impact disturbance and redeposited in three distinct units. The lowermost is a chaotic assemblage of sediment fragments up to 50 cm in size. Above this is a laminated sand-rich unit that deposited as a turbulent flow, and this is overlain by a more fine-grained deposit of silts and clays that settled from a cloud of sediment suspended in the water column. Meteoritic ejecta particles were concentrated near the base of the uppermost unit, where coarse ejecta caught up with the disturbed sediment. Here we will present results from a new suite of cores collected on Polarstern expedition ANT-XVIIU5a. In 2001, the Polarstern returned to the impact area and explored a region of 80,000 sq-km., collecting at least 16 sediment cores with meteoritic ejecta. The known strewn field extends over a region 660 by 200 km. The meteoritic ejecta is most concentrated in cores on the Freeden seamounts, and in the basins to the north, where the amount of meteoritic material deposited on the ocean floor was as much as 3 g/sq-cm. These concentrations drop off to the north and the east to levels as low as approximately 0.1 g/sq-cm. We were unable to sample the impact south and west of the seamounts, as the deposit was buried beyond the reach of our 25 m piston corer. We estimate that ground zero was in the region just north, or northwest, of the seamounts. There is no evidence that the impactor penetrated the ocean floor or formed a crater. The composition of the melted ejecta is inconsistent with mixing between projectile and terrestrial materials other than seawater salts. X-ray radiographs of sediments reveal details not seen in earlier cores. The uppermost impact unit is well-preserved in several cores, found as much as 50 km from the seamounts to the east, north, and west of the seamounts, where at least 25 cm of this unit is preserved. At greater distances burrowing organisms have mixed the sediments so if this unit did exist, it was too thin to survive bioturbation. These finegrained sediments are clearly laminated, and show alternating layers of low- and high-density (meteoritic) sediments, consistent with ripple formation in an energetic flow regime. We have extracted 35 g of meteoritic melt rock and 3 g of meteorite fragments from sieved sediments. Additionally a 9 g, 2.2 cm meteorite was recovered during opening of one core. The fact that 9\\% of the coarse ejecta is unmelted meteorites may be characteristic of deep-ocean impacts. This may have significance for delivery of organic matter to the early Earth by small impacts into primordial oceans, where actual meteorite fragments can survive in significant amounts. However, a large portion of the meteoritic debris is buried rapidly by the sediments disturbed by the impact.

Examining offshore sediment-hosted contaminant transport from Hurricane Katrina: Chapter 7A in Science and the storms-the USGS response to the hurricanes of 2005

USGS Publications Warehouse

Swarzenski, Peter W.; Campbell, Pamela L.; Poore, Richard Z.; Osterman, Lisa E.; Rosenbauer, Robert J.

2007-01-01

A rapid-response expedition was organized after the passage of Hurricane Katrina to investigate potential offshore environmental impacts and storm-induced sediment-transport processes. Both water-column and sediment samples were collected on the Louisiana shelf for a full complement of organic, inorganic, and geochronological tracers. Based on excess lead-210 (210Pb) inventories in cores collected before and after Katrina, the surface sediments and their associated geochemical signatures were considerably affected by the passage of this storm.

Autigenic and Anthropogenic Uranium in the Marine Sediments of the Gulf of California in Front of Santa Rosalia Mining District

NASA Astrophysics Data System (ADS)

Choumiline, K.; Rodríguez-Figueroa, G.; Shumilin, E.; Sapozhnikov, D.

2007-05-01

To verify the possibilities of U enrichments in the marine sedimentary environment of the eastern sector of the central Gulf of Califoria (GC), eleven sediment cores were collected in front of the Santa Rosalia mining region, peninsula of Baja California. Uranium and some other trace element contents in sliced core layers, dried and homogenized, were determined using instrumental neutron activation analysis. Average total U contents in sediments of five cores collected in the open GC in front of Santa Rosalía at sites with water depths from 265 m to 1030 m and in the Guaymas Basin with 2019 m, ranged from 1.36±0.26 mg kg-1 (Guaymas Basin) to 9.31±3.03 mg kg-1 (SR63 core, depth 630 m). To distinguish non-lithogenic U from the lithogenic one, the normalization of total U contents to the concentrations of Sc in the samples was used. That because this element is a reliable indicator of crustal materials, mainly aluminosilicates in the marine sediments. The relative contribution of non-lithogenic (authigenic) U varied from 49.8±3 % (Guaymas Basin) to 84.2±8.2 % (SR62 core) of the total U content in the sediments of the open central GC. Surprisingly, in three sediment cores from the coastal zone adjacent to the town of Santa Rosalía in water depth range 3-6 m very high concentrations of total U were found, ranging from 54.2±7.3 mg kg-1 (SR4 core) to 110±13 mg kg-1 (SR2 core) and exceeding not only U average abundance in the earth´s crust (2.7 mg kg-1), but also its levels found for SR62 core, as well as those reported for natural enrichments of U in suboxic-anoxic environments, e.g. at Mexico and Peru margin sites (3.04 mg kg-1 - 24.54 mg kg-1, McManus et al., 2006). The relative contribution of non-lithogenic U in the sediments of these three anomalous cores varied from 97.2±0.4 % (SR4 core) to 98.80.2 % (SR1 and SR2 cores) of their total U content. The sediments were also depleted in organic C (0.05 % - 0.18 %), which is not typical for marine solid phases enriched in authigenic U. Additional surface sampling around the cores with high levels of U, helped to define the spatial distribution of this element, as well as Co, Cu, Zn, light lanthanides and europium, which also showed "anomalies". The association with anthropogenic impact is discussed because the geochemical fingerprints of these sediments are the same as for solid wastes of copper smelting, which has occurred in Santa Rosalía in the past century till 1984.

Hurricane Sandy washover deposits on southern Long Beach Island, New Jersey

USGS Publications Warehouse

Bishop, James M.; Richmond, Bruce M.; Zaremba, Nicholas J.; Lunghino, Brent D.; Kane, Haunani H.

2016-07-22

Sedimentologic and topographic data from Hurricane Sandy washover deposits were collected from southern Long Beach Island, New Jersey, in order to document changes to the barrier-island beaches, dunes, and coastal wetlands caused by Hurricane Sandy and subsequent storm events. These data will provide a baseline dataset for use in future coastal change descriptive and predictive studies and assessments. The data presented here were collected as part of the U.S. Geological Survey’s Barrier Island and Estuarine Wetland Physical Change Assessment Project (http://coastal.er.usgs.gov/sandy-wetland-assessment/), which aims to assess ecological and societal vulnerability that results from long- and short-term physical changes to barrier islands and coastal wetlands. This report describes data that were collected in April 2015, approximately 2½ years after Hurricane Sandy’s landfall on October 29, 2012. During the field campaign, washover deposits were photographed and described, and sediment cores, sediment samples, and surface-elevation data were collected. Data collected during this study, including sample locations and elevations, core photographs, computed tomography scans, descriptive core logs, sediment grain-size data, and accompanying Federal Geographic Data Committee metadata, are available in the associated U.S. Geological Survey data release (Bishop and others, 2016; http://dx.doi.org/10.5066/F7PK0D7S).

Sedimentologic characteristics of recent washover deposits from Assateague Island, Maryland

USGS Publications Warehouse

Bernier, Julie C.; Zaremba, Nicholas J.; Wheaton, Cathryn J.; Ellis, Alisha M.; Marot, Marci E.; Smith, Christopher G.

2016-06-08

This report describes sediment data collected using sand augers in active overwash zones on Assateague Island in Maryland. Samples were collected by the U.S. Geological Survey (USGS) during two surveys in March/April and October 2014 (USGS Field Activity Numbers [FAN] 2014-301-FA and 2014-322-FA, respectively). The physical characteristics (for example, sediment texture or bedding structure) of and spatial differences among these deposits will provide information about overwash processes and sediment transport from the sandy barrier-island reaches to the back-barrier environments. Metrics derived from these data, such as mean grain size or deposit thicknesses, can be used to ground-truth remote sensing and geophysical data and can also be incorporated into sediment transport models. Data products, including sample location tables, descriptive core logs, core photographs and x-radiographs, the results of sediment grain-size analyses, and Geographic Information System (GIS) data files with accompanying formal Federal Geographic Data Committee (FGDC) metadata can be downloaded from the Data Downloads page.

Updating the Framework Geology of Padre Island National Seashore: Validation of Geophysical Surveys through Sediment Cores

NASA Astrophysics Data System (ADS)

Tuttle, L. F., II; Wernette, P. A.; Houser, C.

2016-12-01

Framework geology has been demonstrated to influence the geomorphology and affect the response of barrier islands to extreme storm events. Therefore, it is vital that we understand the framework geology before we can accurately assess the vulnerability and resiliency of the coast. Geophysical surveys consisting of ground-penetrating radar (GPR) and electromagnetic inductance (EMI) were collected along the length of Padre Island National Seashore (PAIS) to map subsurface infilled paleochannels identified in previous research. The most extensive published survey of PAIS framework geology was conducted in the 1950s as part of dredging the Intracoastal Waterway through Laguna Madre. Using cores and seismic surveys the previous study identified a series of relict infilled paleochannels in dissecting PAIS. The sediment cores presented in our poster were collected in Fall 2016 with a Geoprobe 6712DT. Cores were stored and processed using an X-ray fluorescence (XRF) scanner at the International Ocean Discovery Program repository in College Station, Texas. The XRF data was used to examine mineralogical differences that provide valuable insight into the evolutionary history of the island. This poster presents results from sediment cores collected to validate the geophysical survey data. The broader purpose of this research is to validate the subsurface framework geology features (i.e. infilled paleochannels) in order to more accurately predict future changes to the environmental and economic longevity of PAIS.

Bacteria in deep coastal plain sediments of Maryland: A possible source of CO2 to groundwater

NASA Astrophysics Data System (ADS)

Chapelle, Francis H.; Zelibor, Joseph L., Jr.; Grimes, D. Jay; Knobel, Leroy L.

1987-08-01

Nineteen cores of unconsolidated Coastal Plain sediments obtained from depths of 14 to 182 m below land surface near Waldorf, Maryland, were collected and examined for metabolically active bacteria. The age of the sediments cored range from Miocene to Early Cretaceous. Acridine orange direct counts of total (viable and nonviable) bacteria in core subsamples ranged from 108 to 104 bacteria/g of dry sediment. Direct counts of viable bacteria ranged from 106 to 103 bacteria/g of dry sediment. Three cores contained viable methanogenic bacteria, and seven cores contained viable sulfate-reducing bacteria. The observed presence of bacteria in these sediments suggest that heterotrophic bacterial metabolism, with lignitic organic material as the primary substrate, is a plausible source of CO2 to groundwater. However, the possibility that abiotic processes also produce CO2 cannot be ruled out. Estimated rates of CO2 production in the noncalcareous Magothy/Upper Patapsco and Lower Patapsco aquifers based on mass balance of dissolved inorganic carbon, groundwater flow rates, and flow path segment lengths are in the range 10-3 to 10-5 mmol L-1 yr-1. Isotope balance calculations suggest that aquifer-generated CO2 is much heavier isotopically (˜—10 to + 5 per mil) than lignite (˜-24 per mil) present in these sediments. This may reflect isotopic fractionation during methanogenesis and possibly other bacterially mediated processes.

Vertical profile, source apportionment, and toxicity of PAHs in sediment cores of a wharf near the coal-based steel refining industrial zone in Kaohsiung, Taiwan.

PubMed

Chen, Chih-Feng; Chen, Chiu-Wen; Ju, Yun-Ru; Dong, Cheng-Di

2016-03-01

Three sediment cores were collected from a wharf near a coal-based steel refining industrial zone in Kaohsiung, Taiwan. Analyses for 16 polycyclic aromatic hydrocarbons (PAHs) of the US Environmental Protection Agency priority list in the core sediment samples were conducted using gas chromatography-mass spectrometry. The vertical profiles of PAHs in the core sediments were assessed, possible sources and apportionment were identified, and the toxicity risk of the core sediments was determined. The results from the sediment analyses showed that total concentrations of the 16 PAHs varied from 11774 ± 4244 to 16755 ± 4593 ng/g dry weight (dw). Generally, the vertical profiles of the PAHs in the sediment cores exhibited a decreasing trend from the top to the lower levels of the S1 core and an increasing trend of PAHs from the top to the lower levels of the S2 and S3 cores. Among the core sediment samples, the five- and six-ring PAHs were predominantly in the S1 core, ranging from 42 to 54 %, whereas the composition of the PAHs in the S2 and S3 cores were distributed equally across three groups: two- and three-ring, four-ring, and five- and six-ring PAHs. The results indicated that PAH contamination at the site of the S1 core had a different source. The molecular indices and principal component analyses with multivariate linear regression were used to determine the source contributions, with the results showing that the contributions of coal, oil-related, and vehicle sources were 38.6, 35.9, and 25.5 %, respectively. A PAH toxicity assessment using the mean effect range-median quotient (m-ERM-q, 0.59-0.79), benzo[a]pyrene toxicity equivalent (TEQ(carc), 1466-1954 ng TEQ/g dw), and dioxin toxicity equivalent (TEQ(fish), 3036-4174 pg TEQ/g dw) identified the wharf as the most affected area. The results can be used for regular monitoring, and future pollution prevention and management should target the coal-based industries in this region for pollution reduction.

Geochemical data for mercury, methylmercury, and other constituents in sediments from Englebright Lake, California, 2002

USGS Publications Warehouse

Alpers, Charles N.; Hunerlach, Michael P.; Marvin-DePasquale, Mark C.; Antweiler, Ronald C.; Lasorsa, Brenda K.; De Wild, John F.; Snyder, Noah P.

2006-01-01

Deep coring penetrated the full thickness of material deposited after 1940 at six locations in the reservoir; the cores reached a maximum depth of 32.8 meters below the reservoir floor. At the three deep coring sites closest to Englebright Dam, concentrations of HgT (dry basis) were consistently in the range of 100 to 500 ng/g (nanogram per gram), in sediment dominantly of silt size (median grain size of 0.004 to 0.063 mm [millimeter]). At the deep coring sites located farther upstream, the upper parts of the profile had lower concentrations of HgT, generally ranging from 2 to 100 ng/g, in sediment dominantly of sand size (median grain size from 0.063 to 2 mm). The lower part of the vertical profiles at three upstream coring sites had higher concentrations of HgT than the upper and middle parts of these profiles, and had finer median grain size. The highest median concentration of MeHg (1.1 ng/g) was in the top 2 cm (centimeter) of the shallow box cores. This vertical interval also had the highest value of the ratio of MeHg to HgT, 0.41 percent. Median concentrations of MeHg and median values of MeHg/HgT decreased systematically with depth from 0-4 to 4-8 to 8-12 cm in the shallow cores. However, similar systematic decreases were not observed at the meter scale in the deep cores of the MEM (MEthylMercury) series. The overall median of the ratio MeHg/HgT in the deep cores was 0.25 percent, not much less than the overall median value for the shallow cores (0.33 percent). Mercury-203 radiotracer divalent inorganic mercury (203Hg(II)) was used to determine microbial mercury-methylation potential rates for 11 samples collected from three reservoir locations and various depths in the sediment profile. For the five shallow mercury-methylation subsamples, ancillary geochemical parameters were assayed, including microbial sulfate reduction rates, sulfur speciation (sediment acid volatile sulfide, total reduced sulfur, and pore-water sulfate), iron speciation (sediment acid extractable iron(II), amorphous iron(III), crystalline iron(III) and pore-water iron(II)), pore-water chloride and dissolved organic carbon, and pH, oxidation-reduction potential (Eh) and whole-sediment organic content. The highest potential rates of microbial mercury methylation were measured in shallow (0 to 8 cm depth) sediments (5 to 30 nanograms of mercury per gram dry sediment per day), whereas potential rates for subsamples collected from depths greater than 500 cm were consistently below the detection limit of the radiotracer method (< 0.02 nanogram of mercury per gram dry sediment per day). Chemical analyses of trace and major elements in bed sediment are presented for 202 samples from deep cores from five locations in Englebright Lake. The mean values and standard deviations for selected trace elements were as follows (in micrograms per gram): antimony, 2.4 ? 1.6; arsenic, 69 ? 48; chromium, 134 ? 23; lead, 33 ? 25; and nickel, 87 ? 24. Concentrated samples of heavy-mineral grains, prepared using nine large-volume composite samples from

Description, dissection, and subsampling of Apollo 14 core sample 14230

NASA Technical Reports Server (NTRS)

Fryxell, R.; Heiken, G.

1971-01-01

Core sample 14230, collected at Triplet Crater near the Fra Mauro landing site of the Apollo 14 mission, was dissected in greater detail than any previous core. Sediment from the actual lunar surface was missing, and 6.7 grams of sediment were removed from the base of the core for a portion of the biotest prime sample. Upper and lower portions of the original 70.7-gram core (12.5 centimeters long) were fractured excessively but not mixed stratigraphically. Three major morphologic units and 11 subdivisions were recognized. Dissection provided 55 subsamples in addition to three others made by removing longitudinal sections of the core impregnated with n-butyl methacrylate for use as a permanent documentary record and for studies requiring particles of known orientation.

Geochemistry of mercury and other constituents in subsurface sediment—Analyses from 2011 and 2012 coring campaigns, Cache Creek Settling Basin, Yolo County, California

USGS Publications Warehouse

Arias, Michelle R.; Alpers, Charles N.; Marvin-DiPasquale, Mark C.; Fuller, Christopher C.; Agee, Jennifer L.; Sneed, Michelle; Morita, Andrew Y.; Salas, Antonia

2017-10-31

Cache Creek Settling Basin was constructed in 1937 to trap sediment from Cache Creek before delivery to the Yolo Bypass, a flood conveyance for the Sacramento River system that is tributary to the Sacramento–San Joaquin Delta. Sediment management options being considered by stakeholders in the Cache Creek Settling Basin include sediment excavation; however, that could expose sediments containing elevated mercury concentrations from historical mercury mining in the watershed. In cooperation with the California Department of Water Resources, the U.S. Geological Survey undertook sediment coring campaigns in 2011–12 (1) to describe lateral and vertical distributions of mercury concentrations in deposits of sediment in the Cache Creek Settling Basin and (2) to improve constraint of estimates of the rate of sediment deposition in the basin.Sediment cores were collected in the Cache Creek Settling Basin, Yolo County, California, during October 2011 at 10 locations and during August 2012 at 5 other locations. Total core depths ranged from approximately 4.6 to 13.7 meters (15 to 45 feet), with penetration to about 9.1 meters (30 feet) at most locations. Unsplit cores were logged for two geophysical parameters (gamma bulk density and magnetic susceptibility); then, selected cores were split lengthwise. One half of each core was then photographed and archived, and the other half was subsampled. Initial subsamples from the cores (20-centimeter composite samples from five predetermined depths in each profile) were analyzed for total mercury, methylmercury, total reduced sulfur, iron speciation, organic content (as the percentage of weight loss on ignition), and grain-size distribution. Detailed follow-up subsampling (3-centimeter intervals) was done at six locations along an east-west transect in the southern part of the Cache Creek Settling Basin and at one location in the northern part of the basin for analyses of total mercury; organic content; and cesium-137, which was used for dating. This report documents site characteristics; field and laboratory methods; and results of the analyses of each core section and subsample of these sediment cores, including associated quality-assurance and quality-control data.

The STRATAFORM Project: U.S. Geological Survey geotechnical studies

USGS Publications Warehouse

Minasian, Diane L.; Lee, Homa J.; Locat, Jaques; Orzech, Kevin M.; Martz, Gregory R.; Israel, Kenneth

2001-01-01

This report presents physical property logs of core samples from an offshore area near Eureka, CA. The cores were obtained as part of the STRATAFORM Program (Nittrouer and Kravitz, 1995, 1996), a study investigating how present sedimentation and sediment transport processes influence long-term stratigraphic sequences preserved in the geologic record. The core samples were collected during four separate research cruises to the northern California study area, and data shown in the logs of the cores were collected using a multi-sensor whole core logger. The physical properties collected are useful in identifying stratigraphic units, ground-truthing acoustic imagery and sub-bottom profiles, and in understanding mass movement processes. STRATA FORmation on Margins was initiated in 1994 by the Office of Naval Research, Marine Geology and Geophysics Department as a coordinated multi-investigator study of continental-margin sediment transport processes and stratigraphy (Nittrouer and Kravitz, 1996). The program is investigating the stratigraphic signature of the shelf and slope parts of the continental margins, and is designed to provide a better understanding of the sedimentary record and a better prediction of strata. Specifically, the goals of the STRATAFORM Program are to (Nittrouer and Kravitz, 1995): - determine the geological relevance of short-term physical processes that erode, transport, and deposit particles and those processes that subsequently rework the seabed over time scales - improve capabilities for identifying the processes that form the strata observed within the upper ~100 m of the seabed commonly representing 104-106 years of sedimentation. - synthesize this knowledge and bridge the gap between time scales of sedimentary processes and those of sequence stratigraphy. The STRATAFORM Program is divided into studies of the continental shelf and the continental slope; the geotechnical group within the U.S. Geological Survey provides support to both parts of the project.

Meteoritic Microfossils in Eltanin Impact Deposits

NASA Technical Reports Server (NTRS)

Kyte, Frank T.; Gersonde, Rainer; Kuhn, Gerhard

2006-01-01

We report the unique occurrence of microfossils composed largely of meteoritic ejecta particles from the late Pliocene (2.5 Ma) Eltanin impact event. These deposits are unique, recording the only known km-sized asteroid impact into a deep-ocean (5 km) basin. First discovered as in Ir anomaly in sediment cores that were collected in 1965, the deposits contain nun-sized shock-melted asteroidal material, unmelted meteorite fragments (named the Eltanin meteorite), and trace impact spherules. Two oceanographic expeditions by the FS Polarstern in 1995 and 2001 explored approximately 80,000 sq-km. of the impact region, mapping the distribution of meteoritic ejecta, disturbance of seafloor sediments by the impact, and collected 20 new cores with impact deposits in the vicinity of the Freeden Seamounts (57.3S, 90.5W). Analyses of sediment cores show that the impact disrupted sediments on the ocean floor, redepositing them as a chaotic jumble of sediment fragments overlain by a sequence of laminated sands, silts and clays deposited from the water column. Overprinted on this is a pulse of meteoritic ejecta, likely transported ballistically, then settled through the water column. At some localities, meteoritic ejecta was as much as 0.4 to 2.8 g/cm2. This is the most meteorite-rich locality known on Earth.

Paleomagnetism of late Quaternary drift sediments off the west Antarctica Peninsula

NASA Astrophysics Data System (ADS)

Channell, J. E. T.; Xuan, C.; Hillenbrand, C. D.; Larter, R. D.

2016-12-01

Natural remanant magnetization of a series of piston cores (typically 10 m in lengtth) collected during the JR298 Expedition (January-March 2015) to the west Antarctica Peninsula shows well-defined magnetic components (maximum angular deviations 1°-3°) that potentially record paleomagnetic changes at high southern latitudes. Rock magnetic experiments on the sediments conducted at room and high (up to 700°C) temperatures demonstrate the presence of a low- and a high-coercivity component (mean coercivity of 50-60 mT and 130-140 mT respectively). Paleomagnetic directions from the piston cores are primarily carried by the low-coercivity detrital (titano)magnetite, and are affected by authigenic growth of the high-coercivity maghemite. Maghematization in these sediments is attributed to the low concentrations of labile organic matter and lack of sulfate reduction in an extended oxic zone not penetrated by the piston cores. Despite the varying degree of maghematization, some of the recovered cores yield relative paleointensity (RPI) records that can be matched to a reference RPI record constructed mainly from North Atlantic cores. The resulting age models yield mean sedimentation rates of 4-12 cm/kyr for the JR298 piston cores. RPI may serve as a stratigraphic tool to date sediment cores from the region where traditional isotope stratigraphy is challenging due to the rarity of foraminiferal carbonate.

Preserving Geological Samples and Metadata from Polar Regions

NASA Astrophysics Data System (ADS)

Grunow, A.; Sjunneskog, C. M.

2011-12-01

The Office of Polar Programs at the National Science Foundation (NSF-OPP) has long recognized the value of preserving earth science collections due to the inherent logistical challenges and financial costs of collecting geological samples from Polar Regions. NSF-OPP established two national facilities to make Antarctic geological samples and drill cores openly and freely available for research. The Antarctic Marine Geology Research Facility (AMGRF) at Florida State University was established in 1963 and archives Antarctic marine sediment cores, dredge samples and smear slides along with ship logs. The United States Polar Rock Repository (USPRR) at Ohio State University was established in 2003 and archives polar rock samples, marine dredges, unconsolidated materials and terrestrial cores, along with associated materials such as field notes, maps, raw analytical data, paleomagnetic cores, thin sections, microfossil mounts, microslides and residues. The existence of the AMGRF and USPRR helps to minimize redundant sample collecting, lessen the environmental impact of doing polar field work, facilitates field logistics planning and complies with the data sharing requirement of the Antarctic Treaty. USPRR acquires collections through donations from institutions and scientists and then makes these samples available as no-cost loans for research, education and museum exhibits. The AMGRF acquires sediment cores from US based and international collaboration drilling projects in Antarctica. Destructive research techniques are allowed on the loaned samples and loan requests are accepted from any accredited scientific institution in the world. Currently, the USPRR has more than 22,000 cataloged rock samples available to scientists from around the world. All cataloged samples are relabeled with a USPRR number, weighed, photographed and measured for magnetic susceptibility. Many aspects of the sample metadata are included in the database, e.g. geographical location, sample description, collector, rock age, formation, section location, multimedia images as well structural data, field observations, logistics, surface features, etc. The metadata are entered into a commercial, museum based database called EMu. The AMGRF houses more than 25,000m of deep-sea cores and drill cores as well as nearly 3,000 meters of rotary cored geological material from Antarctica. Detailed information on the sediment cores including location, sediment composition are available in cruise reports posted on the AMGRF web-site. Researchers may access the sample collections through the online websites (http://www-bprc.mps.ohio-state.edu/emuwebusprr and http://www.arf.fsu.edu). Searches may be done using multiple search terms or by use of the mapping feature. The on-line databases provide an essential resource for proposal preparation, pilot studies and other sample based research that should make fieldwork more efficient.

X-ray mineralogy of cores from two Guatemalan caldera lakes

USGS Publications Warehouse

Poppe, Lawrence J.; Paull, Charles K.; Newhall, Christopher G.

1981-01-01

The U.S. Geological Survey (USGS), under the sponsorship of The Agency for International Development, in cooperation with Dartmouth College, collected 13 cores to study the sedimentation in two Guatemalan cauldera lakes, Atitlan and Ayarza.

Questa baseline and premining ground-water quality investigation. 8. Lake-sediment geochemical record from 1960 to 2002, Eagle Rock and Fawn Lakes, Taos County, New Mexico

USGS Publications Warehouse

Church, S.E.; Fey, D.L.; Marot, M.E.

2005-01-01

Geochemical studies of lake sediment from Eagle Rock Lake and upper Fawn Lake were conducted to evaluate the effect of mining at the Molycorp Questa porphyry molybdenum deposit located immediately north of the Red River. Two cores were taken, one from each lake near the outlet where the sediment was thinnest, and they were sampled at 1-cm intervals to provide geochemical data at less than 1-year resolution. Samples from the core intervals were digested and analyzed for 34 elements using ICP-AES (inductively coupled plasma-atomic emission spectrometry). The activity of 137Cs has been used to establish the beginning of sedimentation in the two lakes. Correlation of the geochemistry of heavy-mineral suites in the cores from both Fawn and Eagle Rock Lakes has been used to develop a sedimentation model to date the intervals sampled. The core from upper Fawn Lake, located upstream of the deposit, provided an annual sedimentary record of the geochemical baseline for material being transported in the Red River, whereas the core from Eagle Rock Lake, located downstream of the deposit, provided an annual record of the effect of mining at the Questa mine on the sediment in the Red River. Abrupt changes in the concentrations of many lithophile and deposit-related metals occur in the middle of the Eagle Rock Lake core, which we correlate with the major flood-of-record recorded at the Questa gage at Eagle Rock Lake in 1979. Sediment from the Red River collected at low flow in 2002 is a poor match for the geochemical data from the sediment core in Eagle Rock Lake. The change in sediment geochemistry in Eagle Rock Lake in the post-1979 interval is dramatic and requires that a new source of sediment be identified that has substantially different geochemistry from that in the pre-1979 core interval. Loss of mill tailings from pipeline breaks are most likely responsible for some of the spikes in trace-element concentrations in the Eagle Rock Lake core. Enrichment of Al2O3, Cu, and Zn occurred as a result of chemical precipitation of these metals from ground water upstream in the Red River. Comparisons of the geochemistry of the post-1979 sediment core with both mine wastes and with premining sediment from the vicinity of the Questa mine indicate that both are possible sources for this new component of sediment. Existing data have not resolved this enigma.

A sample-freezing drive shoe for a wire line piston core sampler

USGS Publications Warehouse

Murphy, F.; Herkelrath, W.N.

1996-01-01

Loss of fluids and samples during retrieval of cores of saturated, noncohesive sediments results in incorrect measures of fluid distributions and an inaccurate measure of the stratigraphic position of the sample. To reduce these errors, we developed a hollow drive shoe that freezes in place the lowest 3 inches (75 mm) of a 1.88-inch-diameter (48 mm), 5-foot-long (1.5 m) sediment sample taken using a commercial wire line piston core sampler. The end of the core is frozen by piping liquid carbon dioxide at ambient temperature through a steel tube from a bottle at the land surface to the drive shoe where it evaporates and expands, cooling the interior surface of the shoe to about -109??F (-78??C). Freezing a core end takes about 10 minutes. The device was used to collect samples for a study of oil-water-air distributions, and for studies of water chemistry and microbial activity in unconsolidated sediments at the site of an oil spill near Bemidji, Minnesota. Before freezing was employed, samples of sandy sediments from near the water table sometimes flowed out of the core barrel as the sampler was withdrawn. Freezing the bottom of the core allowed for the retention of all material that entered the core barrel and lessened the redistribution of fluids within the core. The device is useful in the unsaturated and shallow saturated zones, but does not freeze cores well at depths greater than about 20 feet (6 m) below water, possibly because the feed tube plugs with dry ice with increased exhaust back-pressure, or because sediment enters the annulus between the core barrel and the core barrel liner and blocks the exhaust.

Mercury accumulation in Devils Lake, North Dakota effects of environmental variation in closed-basin lakes on mercury chronologies

USGS Publications Warehouse

Lent, R.M.; Alexander, C.R.

1997-01-01

Sediment cores were collected from lakes in the Devils Lake Basin in North Dakota to determine if mercury (Hg) accumulation chronologies from sediment-core data are good indicators of variations in Hg accumulation rates in saline lakes. Sediment cores from Creel Bay and Main Bay, Devils Lake were selected for detailed analysis and interpretation. The maximum Hg concentration in the Creel Bay core was 0.15 micrograms per gram at 8 to 9 centimeters. The maximum Hg concentration in the Main Bay core was 0.07 micrograms per gram at 5 to 7 centimeters. The general decreases in Hg concentrations with depth are attributed to historic variations in atmospheric Hg deposition rate. Hg stratigraphies combined with 210Pb and 137Cs dating analyses yield Hg chronologies that indicate a general increase in Hg accumulation rates in Devils Lake since the middle of the 19th century. Mean modern Hg accumulation rates in Creel Bay were 4.9 nanograms per square centimeter per year, and rates in Main Bay were 1.8 nanograms per square centimeter per year. Mean preindustrial Hg accumulation rates in Creel Bay were 1.2 nanograms per square centimeter per year, and rates in Main Bay were 1.6 nanograms per square centimeter per year. Relatively low Hg concentrations in recent sediments in the Devils Lake Basin, along with similarities in Hg accumulation rates between lakes in the Devils Lake Basin and other lakes in the northern interior of North America, indicate that local sources of Hg are not important sources of Hg. Results of the study indicate that accurate Hg chronologies are discernible in sediment cores collected from saline lakes. However, spatial and temporal variations in lake level and water chemistry common to saline lakes make interpretation of radioisotopic and geochemical chronologies difficult. Hg geochemistry in Devils Lake, and presumably in other saline lakes, is dynamic. The results of this study indicate that the absolute amount of sediment transported to Devils Lake, along with the associated Hg and total organic carbon, and the distribution of sedimentation patterns in Devils Lake may be affected by changing lake levels.

Deposition and chemistry of bottom sediments in Cochiti Lake, north-central New Mexico

USGS Publications Warehouse

Wilson, Jennifer T.; Van Metre, Peter C.

2000-01-01

Bottom sediments were sampled at seven sites in Cochiti Lake in September 1996. Sediment cores penetrating the entire lacustrine sediment sequence were collected at one site near the dam. Surficial sediments were sampled at the near-dam site and six other sites located along the length of the reservoir. Analyses included grain size, major and trace elements, organochlorine compounds, polycyclic aromatic hydrocarbons (PAH's), and radionuclides. Concentrations of trace elements, organic compounds, and radionuclides are similar to those in other Rio Grande reservoirs and are low compared to published sediment-quality guidelines. Most elements and compounds that were detected did not show trends in the age estimated sediment cores with the exception of a decreasing trend in total DDT concentrations from about 1980 to 1992. The mixture of PAH's suggests that the increase is caused by inputs of fuel-related PAH and not combustion- related PAH.

Geochemistry of sulfur in the Florida Everglades; 1994 through 1999

USGS Publications Warehouse

Bates, Anne L.; Orem, W.H.; Harvey, J.W.; Spiker, E. C.

2000-01-01

In this report, we present data on the geochemistry of sulfur in sediments and in surface water, groundwater, and rainwater in the Everglades region in south Florida. The results presented here are part of a larger study intended to determine the roles played by the cycling of carbon, nitrogen, phosphorus, and sulfur in the ecology of the south Florida wetlands. The geochemistry of sulfur in the region is particularly important because of its link to the production of toxic methylmercury through processes mediated by sulfate reducing bacteria. Sediment cores were collected from the Everglades Agricultural Area (EAA), Water Conservation Areas (WCAs) 1A and 2A, from Lake Okeechobee, and from Taylor Slough in the southern Everglades. Water collection was more widespread and includes surface water from WCAs 1A, 2A, 3A, 2B, the EAA, Taylor Slough, Lake Okeechobee, and the Kissimmee River. Groundwater was collected from The Everglades Nutrient Removal Area (ENR) and from WCA 2A. Rainwater was collected at two month intervals over a period of one year from the ENR and from WCA 2A. Water was analyzed for sulfate concentration and sulfate sulfur stable isotopic ratio (34S/32S). Sediment cores were analyzed for total sulfur concentration and/or for concentrations of sulfur species (sulfate, organic sulfur, disulfides, and acid volatile sulfides (AVS)) and for their stable sulfur isotopic ratio. Results show a decrease in total sulfur content (1.57 to 0.61 percent dry weight) with depth in two sediment cores collected in WCA 2A, indicating that there has been an increase in total sulfur content in recent times. A sediment core from the center of Lake Okeechobee shows a decrease in total sulfur content with depth (0.28 to 0.08 percent dry weight). A core from the periphery of the lake (South Bay) likewise shows a decrease in total sulfur content with depth (1.00 to 0.69 percent dry weight), however, the overall sulfur content is greater than that near the center at all depths. This suggests input of sulfur in recent times, especially near the lake margins. Sediments show a general decrease in sulfur concentration with depth, probably because of increases in sulfur input to the marshes in recent times. Regional differences in the concentrations and stable isotopic ratios of sulfate sulfur in surface water show that sulfur contamination to the northern Everglades likely originates from canals draining the EAA.

An assessment of butyltins and metals in sediment cores from the St. Thomas East End Reserves, USVI.

PubMed

Hartwell, S Ian; Apeti, Dennis A; Mason, Andrew L; Pait, Anthony S

2016-11-01

Tributyltin (TBT) concentrations near a marina complex in Benner Bay on St. Thomas, US Virgin Islands, were elevated relative to other areas in a larger study of the southeastern shore of the island. At the request of the USVI Coastal Zone Management Program, sediment cores and surface sediment samples were collected to better define the extent and history of TBT deposition in the vicinity of Benner Bay. The sediment cores were sectioned into 2-cm intervals and dated with 210 Pb and 137 Cs. The core sections and the surface samples were analyzed for butyltins and 16 elements. Deposition rates varied from 0.07-5.0 mm/year, and were highest in the marina complex. Core ages ranged from 54 to 200 years. The bottoms of the cores contained shell hash, but the top layers all consisted of much finer material. Surface concentrations of TBT exceeded 2000 ng Sn/g (dry weight) at two locations. At a depth of 8 cm TBT exceeded 8800 ng Sn/g in the marina complex sediment. Based on the ratio of tributyltin to total butyltins, it appears that the marina sediments are the source of contamination of the surrounding area. There is evidence that vessels from neighboring islands may also be a source of fresh TBT. Copper concentrations increase over time up to the present. Gradients of virtually all metals and metalloids extended away from the marina complex. NOAA sediment quality guidelines were exceeded for As, Pb, Cu, Zn, and Hg.

Mineralogy, geochemistry, and radiocarbon ages of deep sea sediments from the Gulf of Mexico, Mexico

NASA Astrophysics Data System (ADS)

Armstrong-Altrin, John S.; Machain-Castillo, María Luisa

2016-11-01

The mineralogy, geochemistry, and radiocarbon ages of two sediment cores (GMX1 and GMX2) collected from the deep sea area of the Southwestern Gulf of Mexico (∼876-1752 m water depth) were studied to infer the sedimentation rate, provenance, heavy metal contamination, and depositional environment. The sediments are dominated by silt and clay fractions. The mineralogy determined by X-Ray diffractometry for the sediment cores reveals that montmorillonite and muscovite are the dominant clay minerals. The sections between 100 and 210 cm of the sediment cores GMX1 and GMX2, respectively, are characterized by the G. menardii group and G. Inflata planktonic foraminiferal species, which represent the Holocene and Pleistocene, respectively. The radiocarbon-age measurements of mixed planktonic foraminifera varied from ∼268 to 45,738 cal. years B.P and ∼104 to 25,705 cal. years B.P, for the sediment cores GMX1 and GMX2, respectively. The variation in age between the two sediment cores is due to a change in sediment accumulation rate, which was lowest at the location GMX1 (0.006 cm/yr) and highest at the location GMX2 (0.017 cm/yr). The chemical index of alteration (CIA), chemical index of weathering (CIW), and index of chemical maturity (ICV) values indicated a moderate intensity of weathering in the source area. The total rare earth element concentrations (∑REE) in the cores GMX1 and GMX2 vary from ∼94 to 171 and ∼78 to 151, respectively. The North American Shale Composite (NASC) normalized REE patterns showed flat low REE (LREE), heavy REE (HREE) depletion with low negative to positive Eu anomalies, which suggested that the sediments were likely derived from intermediate source rocks. The enrichment factor of heavy metals indicated that the Cd and Zn concentrations in the sediment cores were impacted by an anthropogenic source. The redox-proxy trace element ratios such as V/Cr, Ni/Co, Cu/Zn, (Cu + Mo)/Zn, and Ce/Ce* indicated that the sediments were deposited under an oxic depositional environment. The similarity in major element concentrations, REE content, and the NASC normalised REE patterns between the cores GMX1 and GMX2 revealed that the provenance of sediments remained relatively uniform or constant during deposition for ∼4.5 Ma. The major and trace element based multidimensional discrimination diagrams showed a rift setting for the core sediments, which is consistent with the geology of the Gulf of Mexico.

Sediment data collected in 2014 from Barnegat Bay, New Jersey

USGS Publications Warehouse

Bernier, Julie C.; Stalk, Chelsea, A.; Kelso, Kyle W.; Miselis, Jennifer L.; Tunstead, Rob

2016-05-23

In response to the 2010 Governor’s Action Plan to clean up the Barnegat Bay–Little Egg Harbor (BBLEH) estuary in New Jersey, the U.S. Geological Survey (USGS) partnered with the New Jersey Department of Environmental Protection in 2011 to begin a multidisciplinary research project to understand the physical controls on water quality in the bay. Between 2011 and 2013, USGS scientists mapped the geological and morphological characteristics of the seafloor of the BBLEH estuary using a suite of geophysical tools. However, this mapping effort included only surficial characterization of bay sediments; to verify the sub-surface geophysical data, sediment cores were required.This report serves as an archive of sedimentologic data from 18 vibracores collected from Barnegat Bay between May and August of 2014 by the U.S. Department of Agriculture Natural Resources Conservation Service (NRCS) on behalf of the USGS. The vibracores were collected in conjunction with an ongoing NRCS subaqueous soil survey for the BBLEH estuary. The data presented in this report, including descriptive core logs, core photographs, processed grain-size data, and Geographic Information System (GIS) data files with accompanying formal Federal Geographic Data Committee metadata, can be viewed or downloaded from the Data Products and Downloads page.

A 59-year sedimentary record of metal pollution in the sediment core from the Huaihe River, Huainan, Anhui, China.

PubMed

Wang, Jie; Liu, Guijian; Zhang, Jiamei; Liu, Houqi; Lam, Paul K S

2016-12-01

An approximately 59-year (1955-2014) sedimentary record of metal elements (Cu, Pb, Zn, Ni, Co, Mn, and Fe) in a sediment core, collected from the Huaihe River, Huainan City, Anhui Province, China, was reconstructed by using 210 Pb geochronology. Copper, Zn, Ni, Co, and Mn evaluated by enrichment factor (EF) indicated minor contamination due to water pollution accidents of the Huaihe River that occurred in 1990s and 2004. Lead presented the most severe pollution among the metals studied, especially during 1957-1974. The use of leaded petrol and atmospheric deposition of coal combustion flue gases could have contributed to Pb contamination. In spite of the general good quality (mean sediment pollution index (SPI) 35.69) of the sediment core evaluated by SPI based on the principal component analysis, worse sediment qualities in the upper section (<6 cm, 2004) were still observed, suggesting intensive human activities causing the increasing concentrations of metals in recent decades.

Electrogenic sulfur oxidation in a northern saltmarsh (St. Lawrence Estuary, Canada).

PubMed

Rao, Alexandra; Risgaard-Petersen, Nils; Neumeier, Urs

2016-06-01

Measurements of porewater O2, pH, and H2S microprofiles in intact sediment cores collected in a northern saltmarsh in the St. Lawrence Estuary (Quebec, Canada) revealed the occurrence of electrogenic sulfur oxidation (e-SOx) by filamentous "cable" bacteria in submerged marsh pond sediments in the high marsh. In summer, the geochemical fingerprint of e-SOx was apparent in intact cores, while in fall, cable bacteria were detected by fluorescence in situ hybridization and the characteristic geochemical signature of e-SOx was observed only upon prolonged incubation. In exposed, unvegetated creek bank sediments sampled in the low marsh in summer, cable bacteria developed only in repacked cores of sieved (500 μm), homogenized sediments. These results suggest that e-SOx is suppressed by the activity of macrofauna in exposed, unvegetated marsh sediments. A reduced abundance of benthic invertebrates may promote e-SOx development in marsh ponds, which are dominant features of subarctic saltmarshes as in the St. Lawrence Estuary.

Environmental implications of the use of sulfidic back-bay sediments for dune reconstruction — Lessons learned post Hurricane Sandy

USGS Publications Warehouse

Plumlee, Geoffrey S.; Benzel, William M.; Hoefen, Todd M.; Hageman, Philip L.; Morman, Suzette A.; Reilly, Timothy J.; Adams, Monique; Berry, Cyrus J.; Fischer, Jeffrey; Fisher, Irene

2016-01-01

Some barrier-island dunes damaged or destroyed by Hurricane Sandy's storm surges in October 2012 have been reconstructed using sediments dredged from back bays. These sand-, clay-, and iron sulfide-rich sediments were used to make berm-like cores for the reconstructed dunes, which were then covered by beach sand. In November 2013, we sampled and analyzed partially weathered materials collected from the cores of reconstructed dunes. There are generally low levels of metal toxicants in the reconstructed dune materials. However oxidation of reactive iron sulfides by percolating rainwater produces acid-sulfate pore waters, which evaporate during dry periods to produce efflorescent gypsum and sodium jarosite salts. The results suggest use of sulfidic sediments in dune reconstruction has both drawbacks (e.g., potential to generate acid runoff from dune cores following rainfall, enhanced corrosion of steel bulwarks) and possible benefits (e.g., efflorescent salts may enhance structural integrity).

Pockmarks off Big Sur, California

USGS Publications Warehouse

Paull, C.; Ussler, W.; Maher, N.; Greene, H. Gary; Rehder, G.; Lorenson, T.; Lee, H.

2002-01-01

A pockmark field was discovered during EM-300 multi-beam bathymetric surveys on the lower continental slope off the Big Sur coast of California. The field contains ??? 1500 pockmarks which are between 130 and 260 m in diameter, and typically are 8-12 m deep located within a 560 km2 area. To investigate the origin of these features, piston cores were collected from both the interior and the flanks of the pockmarks, and remotely operated vehicle observation (ROV) video and sampling transects were conducted which passed through 19 of the pockmarks. The water column within and above the pockmarks was sampled for methane concentration. Piston cores and ROV collected push cores show that the pockmark field is composed of monotonous fine silts and clays and the cores within the pockmarks are indistinguishable from those outside the pockmarks. No evidence for either sediment winnowing or diagenetic alteration suggestive of fluid venting was obtained. 14C measurements of the organic carbon in the sediments indicate continuous sedimentation throughout the time resolution of the radiocarbon technique ( ??? 45000 yr BP), with a sedimentation rate of ??? 10 cm per 1000 yr both within and between the pockmarks. Concentrations of methane, dissolved inorganic carbon, sulfate, chloride, and ammonium in pore water extracted from within the cores are generally similar in composition to seawater and show little change with depth, suggesting low biogeochemical activity. These pore water chemical gradients indicate that neither significant accumulations of gas are likely to exist in the shallow subsurface ( ??? 100 m) nor is active fluid advection occurring within the sampled sediments. Taken together the data indicate that these pockmarks are more than 45000 yr old, are presently inactive, and contain no indications of earlier fluid or gas venting events. ?? 2002 Elsevier Science B.V. All rights reserved.

Rapid sedimentation of iron oxyhydroxides in an active hydrothermal shallow semi-enclosed bay at Satsuma Iwo-Jima Island, Kagoshima, Japan

NASA Astrophysics Data System (ADS)

Kiyokawa, Shoichi; Ueshiba, Takuya

2015-04-01

Hydrothermal activity is common in the fishing port of Nagahama Bay, a small semi-enclosed bay located on the southwest coast of Satsuma Iwo-Jima Island (38 km south of Kyushu Island, Japan). The bay contains red-brown iron oxyhydroxides and thick deposits of sediment. In this work, the high concentration and sedimentation rates of oxyhydroxide in this bay were studied and the sedimentary history was reconstructed. Since dredging work in 1998, a thickness of 1.0-1.5 m of iron oxyhydroxide-rich sediments has accumulated on the floor of the bay. To estimate the volume of iron oxyhydroxide sediments and the amount discharged from hydrothermal vents, sediment traps were operated for several years and 13 sedimentary core samples were collected to reconstruct the 10-year sedimentary history of Nagahama Bay. To confirm the timing of sedimentary events, the core data were compared with meteorological records obtained on the island, and the ages of characteristic key beds were thus identified. The sedimentation rate of iron oxyhydroxide mud was calculated, after correcting for sediment input from other sources. The sediments in the 13 cores from Nagahama Bay consist mainly of iron oxyhydroxide mud, three thick tephra beds, and a topmost thick sandy mud bed. Heavy rainfall events in 2000, 2001, 2002, and 2004-2005 coincide with tephra beds, which were reworked from Iwo-Dake ash deposits to form tephra-rich sediment. Strong typhoon events with gigantic waves transported outer-ocean-floor sediments and supplied quartz, cristobalite, tridymite, and albite sands to Nagahama Bay. These materials were redeposited together with bay sediments as the sandy mud bed. Based on the results from the sediment traps and cores, it is estimated that the iron oxyhydroxide mud accumulated in the bay at the relatively rapid rate of 33.3 cm/year (from traps) and 2.8-4.9 cm/year (from cores). The pore water contents within the sediment trap and core sediments are 73%-82% and 47%-67%, respectively. The estimated production of iron oxyhydroxide for the whole fishing port from trap cores is 142.7-253.3 t/year/5000 m2. From sediment cores, however, the accumulation of iron oxyhydroxide sediments on the sea floor is 39-95 t/year/5000 m2. This finding indicates that the remaining 63%-73% of iron was transported out to sea from Nagahama Bay. Even with a high rate of iron oxyhydroxide production, the sedimentation rate of iron oxyhydroxides in the bay is considerably higher than that observed in modern deep-ocean sediments. This example of rapid and abundant oxyhydroxide sedimentation might provide a modern analog for the formation of iron deposits in the geological record, such as ironstones and banded iron formations.

Water volume and sediment volume and density in Lake Linganore between Boyers Mill Road Bridge and Bens Branch, Frederick County, Maryland, 2012

USGS Publications Warehouse

Sekellick, Andrew J.; Banks, William S.L.; Myers, Michael K.

2013-01-01

To assist in understanding sediment loadings and the management of water resources, a bathymetric survey was conducted in the part of Lake Linganore between Boyers Mill Road Bridge and Bens Branch in Frederick County, Maryland. The bathymetric survey was performed in January 2012 by the U.S. Geological Survey, in cooperation with the City of Frederick and Frederick County. A separate, but related, field effort to collect 18 sediment cores was conducted in March and April 2012. Depth and location data from the bathymetric survey and location data for the sediment cores were compiled and edited by using geographic information system (GIS) software. A three-dimensional triangulated irregular network (TIN) model of the lake bottom was created to calculate the volume of stored water in the reservoir. Large-scale topographic maps of the valley prior to inundation in 1972 were provided by the Frederick County Division of Utilities and Solid Waste Management and digitized for comparison with current (2012) conditions in order to calculate sediment volume. Cartographic representations of both water depth and sediment accumulation were produced, along with an accuracy assessment for the resulting bathymetric model. Vertical accuracies at the 95-percent confidence level for the collected data, the bathymetric surface model, and the bathymetric contour map were calculated to be 0.64 feet (ft), 1.77 ft, and 2.30 ft, respectively. A dry bulk sediment density was calculated for each of the 18 sediment cores collected during March and April 2012, and used to determine accumulated sediment mass. Water-storage capacity in the study area is 110 acre-feet (acre-ft) at a full-pool elevation 308 ft above the National Geodetic Vertical Datum of 1929, whereas total sediment volume in the study area is 202 acre-ft. These totals indicate a loss of about 65 percent of the original water-storage capacity in the 40 years since dam construction. This corresponds to an average rate of sediment accumulation of 5.1 acre-ft per year since Linganore Creek was impounded. Sediment thicknesses ranged from 0 to 16.7 ft. Sediment densities ranged from 0.38 to 1.08 grams per cubic centimeter, and generally decreased in the downstream direction. The total accumulated-sediment mass was 156,000 metric tons between 1972 and 2012.

Impacts of pollution derived from ship wrecks on the marine environment on the basis of s/s "Stuttgart" (Polish coast, Europe).

PubMed

Rogowska, Justyna; Wolska, Lidia; Namieśnik, Jacek

2010-11-01

In 1943 the German hospital ship s/s Stuttgart (Lazaretschiff "C") was sunk close to the port of Gdynia (Gulf of Gdańsk - Polish coast). This and other actions (undertaken after the war to remove the wreck) led to pollution of the sea bottom with oil derivatives. During our studies (2009) 11 surface sediment and water samples were collected as well as sediment core samples at 4 locations in order to determine the concentration levels of priority pollutants belonging to polycyclic aromatic hydrocarbons (PAH) and polychlorinated biphenyls (PCB). The concentrations of 16 PAH and 7 PCB were analysed with GC-MS. ΣPAH varied between 11.54 ± 0.39 and 206.7 ± 6.5mg/kg dry weight in the surface sediments, and from 0.686 ± 0.026 to 1291 ± 53 mg/kg dry weight in the core samples. Contamination in the core samples collected may reach a depth of at least 230-240 cm (deepest sample studied). The PAH-group profiles in all surface sediment samples suggest a pyrolytic source of PAH, while the results obtained for core samples indicate a mixed pattern of pyrolytic and petrogenic inputs of PAH. Results obtained may suggest also that fuel residues being present at sea bottom is not crude oil derived but results from coal processing (synthetic fuel). The sum of PCB in surface sediments ranged from 0.761 ± 0.068 to 6.82 ± 0.28 μg/kg dry weight (except for sampling point W2, where ΣPCB was 108.8 ± 4.4 μg/kg dry weight). The strong correlation between PAH and PCB levels, and the fact that PCB are present only in the surface sediments, suggest that the compounds in these sediments got there as a result of emission from urban areas, entering the aquatic environment via atmospheric deposition. PCB levels in the sediment core samples were generally very low and in most cases did not exceed the method quantification limit. Copyright © 2010 Elsevier B.V. All rights reserved.

Hydrocarbon Degradation in Caspian Sea Sediment Cores Subjected to Simulated Petroleum Seepage in a Newly Designed Sediment-Oil-Flow-Through System.

PubMed

Mishra, Sonakshi; Wefers, Peggy; Schmidt, Mark; Knittel, Katrin; Krüger, Martin; Stagars, Marion H; Treude, Tina

2017-01-01

The microbial community response to petroleum seepage was investigated in a whole round sediment core (16 cm length) collected nearby natural hydrocarbon seepage structures in the Caspian Sea, using a newly developed Sediment-Oil-Flow-Through (SOFT) system. Distinct redox zones established and migrated vertically in the core during the 190 days-long simulated petroleum seepage. Methanogenic petroleum degradation was indicated by an increase in methane concentration from 8 μM in an untreated core compared to 2300 μM in the lower sulfate-free zone of the SOFT core at the end of the experiment, accompanied by a respective decrease in the δ 13 C signal of methane from -33.7 to -49.5‰. The involvement of methanogens in petroleum degradation was further confirmed by methane production in enrichment cultures from SOFT sediment after the addition of hexadecane, methylnapthalene, toluene, and ethylbenzene. Petroleum degradation coupled to sulfate reduction was indicated by the increase of integrated sulfate reduction rates from 2.8 SO 4 2- m -2 day -1 in untreated cores to 5.7 mmol SO 4 2- m -2 day -1 in the SOFT core at the end of the experiment, accompanied by a respective accumulation of sulfide from 30 to 447 μM. Volatile hydrocarbons (C2-C6 n -alkanes) passed through the methanogenic zone mostly unchanged and were depleted within the sulfate-reducing zone. The amount of heavier n -alkanes (C10-C38) decreased step-wise toward the top of the sediment core and a preferential degradation of shorter (C30) was seen during the seepage. This study illustrates, to the best of our knowledge, for the first time the development of methanogenic petroleum degradation and the succession of benthic microbial processes during petroleum passage in a whole round sediment core.

Hydrocarbon Degradation in Caspian Sea Sediment Cores Subjected to Simulated Petroleum Seepage in a Newly Designed Sediment-Oil-Flow-Through System

PubMed Central

Mishra, Sonakshi; Wefers, Peggy; Schmidt, Mark; Knittel, Katrin; Krüger, Martin; Stagars, Marion H.; Treude, Tina

2017-01-01

The microbial community response to petroleum seepage was investigated in a whole round sediment core (16 cm length) collected nearby natural hydrocarbon seepage structures in the Caspian Sea, using a newly developed Sediment-Oil-Flow-Through (SOFT) system. Distinct redox zones established and migrated vertically in the core during the 190 days-long simulated petroleum seepage. Methanogenic petroleum degradation was indicated by an increase in methane concentration from 8 μM in an untreated core compared to 2300 μM in the lower sulfate-free zone of the SOFT core at the end of the experiment, accompanied by a respective decrease in the δ13C signal of methane from -33.7 to -49.5‰. The involvement of methanogens in petroleum degradation was further confirmed by methane production in enrichment cultures from SOFT sediment after the addition of hexadecane, methylnapthalene, toluene, and ethylbenzene. Petroleum degradation coupled to sulfate reduction was indicated by the increase of integrated sulfate reduction rates from 2.8 SO42-m-2 day-1 in untreated cores to 5.7 mmol SO42-m-2 day-1 in the SOFT core at the end of the experiment, accompanied by a respective accumulation of sulfide from 30 to 447 μM. Volatile hydrocarbons (C2–C6 n-alkanes) passed through the methanogenic zone mostly unchanged and were depleted within the sulfate-reducing zone. The amount of heavier n-alkanes (C10–C38) decreased step-wise toward the top of the sediment core and a preferential degradation of shorter (C30) was seen during the seepage. This study illustrates, to the best of our knowledge, for the first time the development of methanogenic petroleum degradation and the succession of benthic microbial processes during petroleum passage in a whole round sediment core. PMID:28503172

The Benthic Exchange of O2, N2 and Dissolved Nutrients Using Small Core Incubations.

PubMed

Owens, Michael S; Cornwell, Jeffrey C

2016-08-03

The measurement of sediment-water exchange of gases and solutes in aquatic sediments provides data valuable for understanding the role of sediments in nutrient and gas cycles. After cores with intact sediment-water interfaces are collected, they are submerged in incubation tanks and kept under aerobic conditions at in situ temperatures. To initiate a time course of overlying water chemistry, cores are sealed without bubbles using a top cap with a suspended stirrer. Time courses of 4-7 sample points are used to determine the rate of sediment water exchange. Artificial illumination simulates day-time conditions for shallow photosynthetic sediments, and in conjunction with dark incubations can provide net exchanges on a daily basis. The net measurement of N2 is made possible by sampling a time course of dissolved gas concentrations, with high precision mass spectrometric analysis of N2:Ar ratios providing a means to measure N2 concentrations. We have successfully applied this approach to lakes, reservoirs, estuaries, wetlands and storm water ponds, and with care, this approach provides valuable information on biogeochemical balances in aquatic ecosystems.

Phosphorus fractionation in sediment cores collected in 2005 before and after onset of an Aphanizomenon flos-aquae bloom in upper Klamath Lake, OR, USA

USGS Publications Warehouse

Simon, N.S.; Lynch, D.; Gallaher, T.N.

2009-01-01

We tested the hypothesis that there would be measurable losses of phosphorus (P) from surficial sediments of Upper Klamath Lake (UKL), Oregon, if sediments were a source of P during an algal bloom. We compared concentrations of total and forms of P at various depths in cores collected before and after the onset of a large Aphanizomenon flos-aquae bloom. Concentrations of inorganic P were determined in extraction solutions of MgCl2 (1 M, pH 8), citrate-dithionite-bicarbonate, and 1 M HCl. Sediments below 2 cm were dominated by residual P which is defined as total P minus inorganic P. During the study period, data from the top 2-cm of sediment indicated (a) significant decrease in total P concentration, primarily associated with iron oxyhydroxides at one site, and (b) significant increase in total P concentration associated with residual P at a second site. Data from two other sites indicated no net changes in concentrations of total P. ?? 2009 US Government.

Extraction and speciation of arsenic in lacustrine sediments

USGS Publications Warehouse

Ficklin, W.H.

1990-01-01

Arsenic was partially extracted with 4.OM hydrochloric acid, from samples collected at 25-cm intervals in a 350-cm column of sediment at Milltown Reservoir, Montana and from a 60-cm core of sediment collected at the Cheyenne River Embayment of Lake Oahe, South Dakota. The sediment in both reservoirs is highly contaminated with arsenic. The extracted arsenic was separated into As(III) and As(V) on acetate form Dowex 1-X8 ion-exchange resin with 0.12M HCl eluent. Residual arsenic was sequentially extracted with KClO3 and HCl. Arsenic was determined by graphite-furnace atomic-absorption spectrometry. The analytical results define oxidized and reduced zones in the sediment columns. ?? 1990.

Reconstructed Sediment Mobilization Processes in a Large Reservoir Using Short Sediment Cores

NASA Astrophysics Data System (ADS)

Cockburn, J.; Feist, S.

2014-12-01

Williston Reservoir in northern British Columbia (56°10'31"N, 124°06'33") was formed when the W.A.C. Bennett Dam was created in the late 1960s, is the largest inland body of water in BC and facilitates hydroelectric power generation. Annually the reservoir level rises and lowers with the hydroelectric dam operation, and this combined with the inputs from several river systems (Upper Peace, Finlay, Parsnip, and several smaller creeks) renews suspended sediment sources. Several short-cores retrieved from shallow bays of the Finlay Basin reveal near-annual sedimentary units and distinct patterns related to both hydroclimate variability and the degree to which the reservoir lowered in a particular year. Thin section and sedimentology from short-cores collected in three bays are used to evaluate sediment mobilization processes. The primary sediment sources in each core location is linked to physical inputs from rivers draining into the bays, aeolian contributions, and reworked shoreline deposits as water levels fluctuate. Despite uniform water level lowering across the reservoir, sediment sequences differed at each site, reflecting the local stream inputs. However, distinct organic-rich units, facilitated correlation across the sites. Notable differences in particle size distributions from each core points to important aeolian derived sediment sources. Using these sedimentary records, we can evaluate the processes that contribute to sediment deposition in the basin. This work will contribute to decisions regarding reservoir water levels to reduce adverse impacts on health, economic activities and recreation in the communities along the shores of the reservoir.

Lead isotope ratios in six lake sediment cores from Japan Archipelago: Historical record of trans-boundary pollution sources.

PubMed

Hosono, Takahiro; Alvarez, Kelly; Kuwae, Michinobu

2016-07-15

Sediment cores from six lakes situated from north to south on the Japanese Archipelago were collected during 2009-2010 to investigate the hypothesis that deposition of lead (Pb) was coming from East Asia (including China, South Korea and eastern part of Russia). Accumulation rates and ages of the lake sediment were estimated by the (210)Pb constant rate of supply model and (137)Cs inputs to reconstruct the historical trends of Pb accumulation. Cores from four lakes located in the north and central Japan, showed clear evidence of Pb pollution with a change in the (206)Pb/(207)Pb and (208)Pb/(207)Pb ratios in the recent sediment as compared to the deeper sediment. Among the six studied lakes, significant inputs of anthropogenic lead emissions were observed at Lake Mikazuki (north Hokkaido in north Japan), Lake Chokai (north of Honshu), and Lake Mikuriga (central part of Honshu). Pb isotopic comparison of collected core sediment and previously reported data for wet precipitation and aerosols from different Asian regions indicate that, before 1900, Pb accumulated in these three lakes was not affected by trans-boundary sources. Lake Mikazuki started to receive Pb emissions from Russia in early 1900s, and during the last two decades, this lake has been affected by trans-boundary Pb pollution from northern China. Lake Chokai has received Pb pollutant from northern China since early 1900s until 2009, whereas for the Lake Mikuriga the major Pb contaminant was transported from southern China during the past 100years. The results of our study demonstrate that Japan Archipelago has received trans-boundary Pb emissions from different parts of East Asian region depending on location, and the major source region has changed historically. Copyright © 2016 Elsevier B.V. All rights reserved.

Lignin geochemistry of a Late Quaternary sediment core from Lake Washington

NASA Astrophysics Data System (ADS)

Hedges, John I.; Ertel, John R.; Leopold, Estella B.

1982-10-01

Long-term lignin stability and paleovegetation patterns were investigated using CuO oxidation products of sediments from an 11 m core of Late Quaternary sediment collected from the mid-basin of Lake Washington, Washington State. Relatively constant yields of lignin-derived phenols (normalized to organic carbon) from the entire core indicate minimal in situ lignin degradation over the last 13,000 years. Compositional patterns within the phenolic suite and increased corresponding yields from baseextracted sediments indicate that sedimentary lignins are present predominantly as well preserved plant tissue fragments. Abundance patterns of vanillyl, syringyl, and cinnamyl phenols record four distinct sequences within the core characterized by: (a) high concentrations of gymnosperm wood in a basal horizon of glacial flour, 11-10 m; (b) an essentially pure mixture of nonwoody angiosperm tissues in late Pleistocene sediments, 10-8 m; (c) relatively high concentrations of angiosperm woods in the bottom half of a limnic peat sequence deposited approximately 10,000-7,000 years B.P., 8-4 m; and (d) a progressive enrichment in gymnosperm woods at the expense of angiosperm woods over the last 7,000 years in the upper limnic peat, 4-0 m. Vascular plant tissues account for less than half the total sedimentary organic carbon throughout the core.

Geomorphology-based interpretation of sedimentation rates from radiodating, lower Passaic River, New Jersey, USA.

PubMed

Erickson, Michael J; Barnes, Charles R; Henderson, Matthew R; Romagnoli, Robert; Firstenberg, Clifford E

2007-04-01

Analysis of site geomorphology and sedimentation rates as an indicator of long-term bed stability is central to the evaluation of remedial alternatives for depositional aquatic environments. In conjunction with various investigations of contaminant distribution, sediment dynamics, and bed stability in the Passaic River Estuary, 121 sediment cores were collected in the early 1990s from the lower 9.7 km of the Passaic River and analyzed for lead-210 (210Pb), cesium-137 (137Cs), and other analytes. This paper opportunistically uses the extensive radiochemical dataset to examine the spatial patterns of long-term sedimentation rates in, and associated geomorphic aspects of, this area of the river. For the purposes of computing sedimentation rates, the utility of the 210Pb and 137Cs depositional profiles was assessed to inform appropriate interpretation. Sedimentation rates were computed for 90 datable cores by 3 different methods, depending on profile utility. A sedimentation rate of 0 was assigned to 17 additional cores that were not datable and for which evidence of no deposition exists. Sedimentation patterns were assessed by grouping results within similar geomorphic areas, delineated through inspection of bathymetric data. On the basis of channel morphology, results reflect expected patterns, with the highest sedimentation rates observed along point bars and channel margins. The lowest rates of sedimentation (and the largest percentage of undatable cores) were observed in the areas along the outer banks of channel bends. Increasing sedimentation rates from upstream to downstream were noted. Average and median sedimentation rates were estimated to be 3.8 and 3.7 cm/y, respectively, reflecting the highly depositional nature of the Passaic River estuary. This finding is consistent with published descriptions of long-term geomorphology for Atlantic Coastal Plain estuaries.

The effect of mining on the sediment - trace element geochemistry of cores from the Cheyenne River arm of Lake Oahe, South Dakota, U.S.A.

USGS Publications Warehouse

Horowitz, A.J.; Elrick, K.A.; Callender, E.

1988-01-01

Six cores, ranging in length from 1 to 2 m, were collected in the Cheyenne River arm of Lake Oahe, South Dakota, to investigate potential impacts from gold-mining operations around Lead, South Dakota. Sedimentation rates in the river arm appear to be event-dominated and rapid, on the order of 6-7 cm yr.-1. All the chemical concentrations in the core samples fall within the wide ranges previously reported for the Pierre Shale of Cretaceous age and with the exception of As, generally are similar to bed sediment levels in the Cheyenne River, Lake Oahe and Foster Bay. Based on the downcore distribution of Mn, it appears that reducing conditions exist in the sediment column of the river arm below 2-3 cm. The reducing conditions do not appear to be severe enough to produce differentiation of Fe and Mn throughout the sediment column in the river arm. Cross-correlations for high-level metal-bearing strata within the sediment column can be made for several strata and for several cores; however, cross-correlations for all the high-level metal-bearing strata are not feasible. As is the only element which appears enriched in the core samples compared to surface sediment levels. Well-crystallized arsenopyrite was found in high-As bearing strata from two cores and probably was transported in that form from reducing sediment-storage sites in the banks or floodplains of Whitewood Creek and the Belle Fourche River. It has not oxidized due to the reducing conditions in the sediment column of the Cheyenne River arm. Some As may also be transported in association with Fe- and Mn-oxides and -hydroxides, remobilized under the reducing conditions in the river arm, and then reprecipitated in authigenic sulfide phases. In either case, the As appears to be relatively immobile in the sediment column. ?? 1988.

Evaluation of dredged material proposed for ocean disposal from Hudson River, New York

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gardiner, W.W.; Barrows, E.S.; Antrim, L.D.

1996-09-01

The Hudson River (Federal Project No. 41) was one of seven waterways that the U.S. Army Corps of Engineers-New York District (USACE-NYD) requested the Battelle Marine Sciences Laboratory (MSL) to sample and evaluate for dredging and disposal in March 1994. Sediment samples were collected from the Hudson River. Tests and analyses were conducted on Hudson River sediment core samples. The evaluation of proposed dredged material from the Hudson River included bulk sediment chemical analyses, chemical analyses of site water and elutriate, water-column and benthic acute toxicity tests, and bioaccumulation studies. Individual sediment core samples collected from Hudson River were analyzedmore » for grain size, moisture content, and total organic carbon (TOC). A composite sediment sample, representing the entire area proposed for dredging, was analyzed for bulk density, specific gravity, metals, chlorinated pesticides, polychlorinated biphenyl (PCB) congeners, polynuclear aromatic hydrocarbons (PAH), and 1,4-dichlorobenzene. Site water and elutriate water, prepared from the suspended-particulate phase (SPP) of Hudson River sediment, were analyzed for metals, pesticides, and PCBS. Water-column or SPP toxicity tests were performed with three species. Benthic acute toxicity tests were performed. Bioaccumulation tests were also conducted.« less

Persistence and Bioavailability of DDT in a Coastal Salt Marsh

NASA Astrophysics Data System (ADS)

Rowlett, K.; Weathers, N.; Morrison, A.; White, H. K.

2016-02-01

DDT (dichlorodiphenyltrichloroethane) was a widely-used pesticide in the United States throughout the 1900s. In 1972, the EPA banned the use of DDT due to fears of severe bioaccumulation and toxicity in animals. However, the compound persists in measurable quantities in the environment, leading to questions surrounding its current bioavailability in key ecosystems such as coastal marshes. For this study a sediment core was collected in 2015 from a salt marsh in Dover, Delaware and the sediments and plant matter were analyzed for the presence of DDT and three of its main biological metabolites: DDD, DDE, and DDMU (collectively, DDX). Samples were extracted in toluene and analyzed for DDX via gas chromatography with mass spectrometry (GC/MS) operated in selected ion monitoring (SIM) mode. The initial down-core profile revealed that the maximum concentration of DDX in both plant matter (>1mm in size) and sediments (<250µm in size) was at 22-30cm below the marsh surface, corresponding to the time of DDT application, as determined by 210Pb-dating. After initial analysis of the concentration of DDX in the sediment core, a passive sampling method using low-density polyethylene (LDPE) was employed to measure the bioavailability of the DDX compounds in the collected sediments. Bioavailability experiments with LDPE are ongoing and results will be discussed. This study will contribute to our overall understanding of the persistence of DDT in the environment by further elucidating the association of DDX compounds with plants and sedimentary material as well as their bioavailability with respect to these associations.

Origin of increased terrigenous supply to the NE South American continental margin during Heinrich Stadial 1 and the Younger Dryas

NASA Astrophysics Data System (ADS)

Zhang, Yancheng; Chiessi, Cristiano M.; Mulitza, Stefan; Zabel, Matthias; Trindade, Ricardo I. F.; Hollanda, Maria Helena B. M.; Dantas, Elton L.; Govin, Aline; Tiedemann, Ralf; Wefer, Gerold

2015-12-01

We investigate the redistribution of terrigenous materials in the northeastern (NE) South American continental margin during slowdown events of the Atlantic Meridional Overturning Circulation (AMOC). The compilation of stratigraphic data from 108 marine sediment cores collected across the western tropical Atlantic shows an extreme rise in sedimentation rates off the Parnaíba River mouth (about 2°S) during Heinrich Stadial 1 (HS1, 18-15 ka). Sediment core GeoB16206-1, raised offshore the Parnaíba River mouth, documents relatively constant 143Nd/144Nd values (expressed as εNd(0)) throughout the last 30 ka. Whereas the homogeneous εNd(0) data support the input of fluvial sediments by the Parnaíba River from the same source area directly onshore, the increases in Fe/Ca, Al/Si and Rb/Sr during HS1 indicate a marked intensification of fluvial erosion in the Parnaíba River drainage basin. In contrast, the εNd(0) values from sediment core GeoB16224-1 collected off French Guiana (about 7°N) suggest Amazon-sourced materials within the last 30 ka. We attribute the extremely high volume of terrigenous sediments deposited offshore the Parnaíba River mouth during HS1 to (i) an enhanced precipitation in the catchment region and (ii) a reduced North Brazil Current, which are both associated with a weakened AMOC.

Microbial diversity in Cenozoic sediments recovered from the Lomonosov Ridge in the Central Arctic basin.

PubMed

Forschner, Stephanie R; Sheffer, Roberta; Rowley, David C; Smith, David C

2009-03-01

The current understanding of microbes inhabiting deeply buried marine sediments is based largely on samples collected from continental shelves in tropical and temperate latitudes. The geographical range of marine subsurface coring was expanded during the Integrated Ocean Drilling Program Arctic Coring Expedition (IODP ACEX). This expedition to the ice-covered central Arctic Ocean successfully cored the entire 428 m sediment stack on the Lomonosov Ridge during August and September 2004. The recovered cores vary from siliciclastic sediment low in organic carbon (< 0.2%) to organic rich ( approximately 3%) black sediments that rapidly accumulated in the early middle Eocene. Three geochemical environments were characterized based on chemical analyses of porewater: an upper ammonium oxidation zone, a carbonate dissolution zone and a deep (> 200 m below sea floor) sulfate reduction zone. The diversity of microbes within each zone was assessed using 16S rRNA phylogenetic markers. Bacterial 16S rRNA genes were successfully amplified from each of the biogeochemical zones, while archaea was only amplified from the deep sulfate reduction zone. The microbial communities at each zone are phylogenetically different and are most closely related to those from other deep subsurface environments.

Data on sediment quality and concentrations of polychlorinated biphenyls from the Lower Neponset River, Massachusetts, 2002-03

USGS Publications Warehouse

Breault, Robert F.; Cooke, Matthew G.; Merrill, Michael

2004-01-01

The U.S. Geological Survey, in cooperation with the Massachusetts Executive Office of Environmental Affairs Department of Fish and Game Riverways Program, and the U.S. Environmental Protection Agency, studied sediment and water quality in the lower Neponset River, which is a tributary to Boston Harbor. Grab and core samples of sediment were tested for elements and organic compounds including polyaromatic hydrocarbons, organochlorine pesticides, and polychlorinated biphenyls. Physical properties of sediment samples, including grain size, were also measured. Selected sediment-core samples were tested for reactive sulfides and metals by means of the toxicity characteristic leaching procedure, which are sediment-disposal-related tests. Water quality, with respect to polychlorinated biphenyl contamination, was determined by testing samples collected by PISCES passive-water-column samplers for polychlorinated biphenyl congeners. Total concentrations of polychlorinated biphenyls were calculated by congener and by Aroclor.

Tracking recent climate and anthropogenic change in Central America in sediments form the lower fan of the Rio Yaqui, Gulf of California, Mexico

NASA Astrophysics Data System (ADS)

Aiello, I. W.; Ravelo, A. C.; Moraes, R.; Swarzenski, P. W.

2015-12-01

We report the results of preliminary sedimentologic analyses of a ~3.3m long piston core (P13) collected in the lower fan of the Rio Yaqui (Guaymas Basin, Gulf of California; depth, 1859m) by UNAM's (Universidad Nacional Autónoma de México) research ship El Puma in 2014. The core was collected to test the potential for high-resolution reconstructions of basin-scale paleoclimate in the Pacific and the Mesoamerican region. Shipboard and post-cruise analyses include magnetic susceptibility (MS), smear slide counts and laser diffraction particle size analysis. The core is being analyzed for X-Ray Fluorescence (XRF) and color reflectance, and a 210Pb age model is being constructed. Preliminary results show that Rio Yaqui lower fan sediment differs significantly from that in the Guaymas Basin, which is dominantly diatom ooze. The lower ~2m of core P13 show prominent alternations (~10-20cm) between very-fine-grained, clay intervals characterized by higher MS and mixed diatom and clay intervals, with coarser grain size and lower MS values. In contrast, the upper ~1m has distinctive high MS sand turbidites alternating with diatom-rich layers. Previous core studies from nearby ODP Leg 64 site show sedimentation rates of ~1.2 m/ka; as these sites are further away from the Yaqui delta the sedimentation rates for core P13 should be higher possibly recording only the last few hundred years of sedimentation. Clay/diatom cycles in the lower part of the core could record decadal- or ENSO-scale wet/aridity cycles in the Sonoran Mainland. Conversely, the coarser siliciclastic intervals and the diatom layers in the upper part of the core could reflect the last few decades of land usage in the watershed of the Rio Yaqui, the most important river in the state of Sonora, Mexico. These include large modifications to the river's hydrography (e.g. construction of dams and aqueducts), rapidly expanding mass agricultural practices in the region, and increased eutrophication in the Gulf.

Determining rates of sediment accumulation on the Mekong shelf: Timescales, steady-state assumptions, and radiochemical tracers

NASA Astrophysics Data System (ADS)

DeMaster, D. J.; Liu, J. P.; Eidam, E.; Nittrouer, C. A.; Nguyen, T. T.

2017-09-01

Thirty-two kasten cores, collected from the proximal Mekong continental shelf, have been analyzed for their excess 210Pb distributions in an effort to establish rates of sediment accumulation over the past 100 years. The length of the cores varied from 0.5 to 3 m, and stations sampled topset, foreset, and bottomset beds (water depths 7-21 m). Apparent excess 210Pb sediment accumulation rates ranged from > 10 cm/y (no down-core decrease of excess activity over 300 cm core length) near the Song Hau river mouth, to 1-3 cm/y in topset and foreset beds within 20-50 km of the river mouth, to rates as low as 0.4 cm/y in cores from bottomset beds. The 210Pb sediment accumulation rates yield an overall sediment burial rate of 6.1 × 1013 g/y for the proximal deltaic deposits, which corresponds to 43% of the total modern Mekong sediment burial on the southern Vietnam shelf (1.4 × 1014 g/y; based on our 210Pb and seismic data and 210Pb data from the literature). This shelf burial rate is in reasonable agreement with current long-term estimates of Mekong River sediment discharge (1.3-1.6 × 1014 g/y) from the literature. The inventory of excess 210Pb in the proximal Mekong deltaic deposits indicates that the shoreward flow of offshore water (entrained during river/ocean mixing) is approximately twice the flow of the Mekong freshwater discharge. Organic-carbon 14C ages were measured on 10 cores from the proximal Mekong delta and compared to 210Pb sediment accumulation rates in the same core. The 210Pb accumulation rates in all 10 cores were considered to be more robust and accurate than the 14C geochronologies, primarily because of down-core variations in the source of organic carbon deposited on the seafloor (old terrestrial carbon versus younger marine carbon). Variations in the source of organic carbon accumulating in the seabed were resolved by measuring the δ13C value of the seabed organic carbon.

Phosphorus speciation and its bioavailability in sediments of the Jiaozhou Bay

NASA Astrophysics Data System (ADS)

Kang, Xuming; Song, Jinming; Yuan, Huamao; Shi, Xin; Yang, Weifeng; Li, Xuegang; Li, Ning; Duan, Liqin

2017-03-01

Phosphorus (P) is an important macronutrient that can limit primary productivity in coastal marine ecosystems. In this study, four sediment cores were collected in the Jiaozhou Bay to study the phosphorus forms and their bioavailability, including exchangeable or loosely sorbed P (Ex-P), iron-bound P (Fe-P), authigenic P (Ca-P), detrital P (De-P) and organic P (OP), which were separated and quantified using a sequential extraction method (SEDEX). The results showed that the concentration of total P (TP) in core sediments ranged from 6.23 to 10.46 μmol/g, and inorganic P (IP) was the dominated P form. Fe-P and De-P were the main chemical forms of IP in core sediments. The profile variation of OP presented the most significant among the phosphorus forms. Whereas the concentrations of Ex-P, Fe-P, and Ca-P varied slightly with depth, indicating that the transformation of Ex-P, Fe-P, Ca-P, and OP could occur during sedimentary P burial. Moreover, the distribution of P species was influenced by many factors, including terrigenous input, biological processes, organic matter degradation and increasing human activities. High total organic carbon (TOC)/OP ratio occurred in the Jiaozhou Bay, ranging from 73 to 472 (average, 180 ± 81) in core sediments, which was caused by the increasing terrestrial organic matter. The ratio of TOC/Preactive ranged from 24 to 101 (average 46 ± 15) in core sediments (lower than the Redfield ratio), implying a surplus of sedimentary reactive P compared with TOC. Potential bioavailable P (BAP) accounted for about 28.2-60.8% (average, 47.1 ± 7.4%) of TP in core sediments, and presented an increasing trend since 1980s, which might be responsible for the shift of phytoplankton community composition during these decades.

Radiocarbon dating Arctic deep marine sediment to refine the usage of Mn pattern as a stratigraphic tool

NASA Astrophysics Data System (ADS)

Chiu, Pin-Yao Bernie; Löwemark, Ludvig

2016-04-01

The distinctive pattern of Mn content in Arctic deep marine sediment has been used as a proxy to indicate glacial-interglacial cyclicity (Löwemark et al., 2014). As has been observed in many sediment cores, Mn peaks correspond to warm interglacial periods. In order to improve the preciseness of Mn pattern as a proxy, we collected the foraminifera Neogloboquadrina pachyderma (sinistral) from brownish, Mn-rich layers, and performed radiocarbon dating on selected cores collected during the LOMROG07, LOMROG09 and LOMROG12 expeditions. Additional cores form the YMER and AO96 expeditions are also included. Based on our general understanding of the Mn system in the Arctic Ocean, we predicted a Mn pattern with a high peak in the uppermost core top, representing the Holocene. This Holocene peak in Mn is separated from the underlying warm period MIS 3 by a Mn-poor interval also characterized by a drop in Ca. This Mn and Ca poor interval reperesents MIS 2 and the LGM. Older warm periods, such as MIS 3, 5, 7 etc will display a similar pattern with distinct Mn peaks, separated by Mn minima representing cold iperiods For example, the MIS 5 sometimes shown a distinct pattern with three Mn peaks representing MIS 5a, 5c and 5e. However, there are still some limitations in the applicability of Mn stratigraphy, such as the remobilization of the Mn layer and the core-top loss during coring. We performed AMS carbon 14 dating on more than 10 cores, and the result revealed several cases of lost core tops, leading to depletion or complete loss of the Holocene interval. In several cores, our AMS dating revealed a hiatus in the MIS2 interval. The complete lack of MIS2 sediment likely is the result of extremely slow sedimentation rate due to severe sea ice conditions, while places with records of LGM may be the result of polynyas within the sea ice, or certain circulation pattern. Consequently, although Mn pattern can be used as a preliminary tool to identify glacial-interglacial cycles, the loss core tops and glacial hiatuses limits the usage and accuracy of the correlation of Mn stratigraphies. Therefore, additional radiocarbon dating can refine our understanding of the Mn patterns in Arctic marine sediment and help to make it a better proxy for both paleoenvironmental reconstructions and for the age models. Further study on the cause of hiatus often encountered in the LGM interval is necessary to ensure the usefulness of Mn stratigraphy.

Polychaete Tubes, Turbulence, and Erosion of Fine-Grained Sediment

NASA Astrophysics Data System (ADS)

Kincke-Tootle, A.; Frank, D. P.; Briggs, K. B.; Calantoni, J.

2016-02-01

The role of polychaete tubes protruding through the benthic boundary layer in promoting or hindering erosion of fine-grained sediment was examined in laboratory experiments. Diver core samples of the top 10cm of sediment were collected west of Trinity Shoal off the Louisiana coast in 10-m depth. Diver cores were used in laboratory experiments conducted in a unidirectional flume. Tubes that were constructed by polychaetes, which comprised 70% of the species from the study area, were inserted into the core sediment surface. The sediment cores were then placed in the 2-m long test section of a small oscillatory flow tunnel and high-speed, stereo particle image velocimetry was used to determine the 2-dimensional, 3-component fluid velocity at high temporal (100 Hz) and spatial (< 1mm vector spacing) resolution. The tubes that protruded above the boundary layer allowed vortices to be initiated. Tubes are made up of shell fragments and fine-grained sediment, allowing for some rigidity and resistance to the flow. Rigidity determines the resistance causing small-scale eddies to form. The small-scale turbulence incited scour erosion, allowing fine-grained particles to be suspended into the water and in some cases coarser particles to be mobilized. Less-rigid tubes succumb to the shear stress, inhibit the formation of small-scale eddies, limit sediment erodibility, and increase the critical shear stress of the sediment. Discussion will focus on a modification to the critical Shields parameter to account for the effects of benthic biological activity.

Geochemical Dataset of the Rhone River Delta (Lake Geneva) Sediments - Disentangling Human Impacts from Climate Change

NASA Astrophysics Data System (ADS)

Silva, T. A.; Girardclos, S.; Loizeau, J. L.

2016-12-01

Lake sediment records are often the most complete continental archives. In the last 200 years, in addition to climatic variability, humans have strongly impacted lake watersheds around the world. During the 20th century the Rhone River and its watershed upstream Lake Geneva (Switzerland/France) have been subject to river channelization, dam construction, water flow regulation, water and sediment abstraction as well as various land use changes. Under the scope of the SEDFATE project (Swiss National Science Foundation nº147689) we address human and climatic impact on the sediment transfer from the Rhone River watershed to Lake Geneva. Nineteen short sediment cores were collected in the Rhone River delta area in May 2014. Cores have been scanned with MSCL and XRF, sub-sampled every 1cm and 8 cores were dated by radiometric methods (137Cs and 210Pb). Photographs taken right after core opening were used for lithological description and in addition to MSCL data were used to correlate cores. Core dating shows that mass accumulation rates decreased in the 1964-1986 interval and then increased again in the interval between 1986-2014. XRF elements and ratios, known to indicate detrital sources (Al, Al/Si, Fe, K, Mn, Rb, Si, Ti, Ti/Ca), show that clastic input diminished from 1964 to 1986 and re-increased to the present. Other elemental (Zr/Rb, Zr/K, Si/Ti) and geophysical data (magnetic susceptibility) combined with lithology identify density flow deposits vs hemipelagic sedimentation. Changes in frequency of these event deposits indicate changes in the sedimentation patterns in the Rhone River sublacustrine delta during the last century. From these results we hypothesize that a significant sediment amount was abstracted from the system after the major dam constructions in the 1950's and that, since the 1990's, a contrary signal is due to increased sediment loads that follows glacial melting due to global warming.

A Regional Survey of River-plume Sedimentation on the Mississippi River Delta Front

NASA Astrophysics Data System (ADS)

Courtois, A. J.; Bentley, S. J.; Xu, K.; Georgiou, I. Y.; Maloney, J. M.; Miner, M. D.; Chaytor, J. D.; Smith, J.

2017-12-01

Many studies of the Mississippi River and Delta (MRD) have shown historic declines in sediment load reaching the main river distributaries over the last few decades. Recent studies also reported that 50% of the suspended load during floods is sequestered within the delta. While the impact of declining sediment load on wetland loss is well documented, submarine sedimentary processes on the delta front during this recent period of declining sediment load are understudied. To better understand modern sediment dispersal and deposition across the Mississippi River Delta Front, 31 multicores were collected in June 2017 from locations extending offshore from Southwest Pass, South Pass, and Pass a Loutre (the main river outlets) in water depths of 25-280 m. Core locations were selected based on multibeam bathymetry and morphology collected by the USGS in May 2017; the timing of collection coincided with the end of annual peak discharge on the Mississippi River. This multi-agency survey is the first to study delta-front sedimentary processes regionally with such a wide suite of tools. Target locations for coring included the dominant depositional environments: mudflow lobes, gullies, and undisturbed prodelta. Cores were subsampled at 2 cm intervals and analyzed for Beryllium-7 activity via gamma spectrometry; in such settings, Be-7 can be used as a tracer of sediment recently delivered from fluvial origin. Results indicate a general trend of declining Be-7 activity with increasing distance from source, and in deeper water. Inshore samples near Southwest Pass show the deepest penetration depth of Be-7 into the sediment (24-26 cm), which is a preliminary indicator of rapid seasonal sedimentation. Nearshore samples from South Pass exhibited similar Be-7 penetration depths, with results near Pass a Loutre to 14-16 cm depth. Be-7 remains detectable to 2 cm in water 206 m deep, approximately 20 km from South Pass. Sediment dispersal remains impressive offshore from all three major river outlets, despite overall decline of sediment load in recent decades, and pronounced declines for South Pass and Pass a Loutre. Future research will focus on relationships among changing sediment loads, dispersal patterns, and sediment transport by mudflows, which are an important process for dispersal after initial deposition.

Spatial distribution and trends in trace elements, polycyclic aromatic hydrocarbons, organochlorine pesticides, and polychlorinated biphenyls in Lake Worth sediment, Fort Worth, Texas

USGS Publications Warehouse

Harwell, Glenn Richard; Van Metre, Peter C.; Wilson, Jennifer T.; Mahler, Barbara J.

2003-01-01

In spring 2000, the Texas Department of Health issued a fish consumption advisory for Lake Worth in Fort Worth, Texas, because of elevated concentrations of polychlorinated biphenyls (PCBs) in fish. In response to the advisory and in cooperation with the U.S. Air Force, the U.S. Geological Survey collected 21 surficial sediment samples and three gravity core sediment samples to assess the spatial distribution and historical trends of selected hydrophobic contaminants, including PCBs, and to determine, to the extent possible, sources of hydrophobic contaminants to Lake Worth. Compared to reference (background) concentrations in the upper lake, elevated PCB concentrations were detected in the surficial sediment samples collected in Woods Inlet, which receives surface runoff from Air Force facilities and urban areas. Gravity cores from Woods Inlet and from the main part of the lake near the dam indicate that the concentrations of PCBs were three to five times higher in the 1960s than in 2000. A regression method was used to normalize sediment concentrations of trace elements for natural variations and to distinguish natural and anthropogenic contributions to sediments. Concentrations of several trace elements—cadmium, chromium, copper, lead, and zinc—were elevated in sediments in Woods Inlet, along the shoreline of Air Force facilities, and in the main lake near the dam. Concentrations of these five trace elements have decreased since 1970. Polycyclic aromatic hydrocarbons also were elevated in the same areas of the lake. Concentrations of total polycyclic aromatic hydrocarbons, normalized with organic carbon, were mostly stable in the upper lake but steadily increased near the dam, except for small decreases since 1980. The Woods Inlet gravity core showed the largest increase of the three core sites beginning about 1940; total polycyclic aromatic hydrocarbon concentrations in post-1940 sediments from the core showed three apparent peaks about 1960, 1984, and 2000. The concentrations of organochlorine pesticides were low relative to consensus-based sediment-quality guidelines and either decreased or remained constant since 1970. The two likely sources of hydrophobic contaminants to the lake are urban areas around the lake and the drainage area of Meandering Road Creek that contributes runoff to Woods Inlet and includes Air Force facilities.

Tidal and flood signatures of settling particles in the Gaoping submarine canyon (SW Taiwan) revealed from radionuclide and flow measurements

USGS Publications Warehouse

Huh, C.-A.; Liu, J.T.; Lin, H.-L.; Xu, J. P.

2009-01-01

Sediment transport and sedimentation processes in the Gaoping submarine canyon were studied using sediment trap and current meter moorings deployed at a location during the winter (January-March) and the summer (July-September) months in 2008. At the end of each deployment, sediment cores were also collected from the canyon floor at the mooring site. Samples from sediment traps and sediment cores were analyzed for 210Pb and 234Th by gamma spectrometry. In conjunction with particle size and flow measurements, the datasets suggest that sediment transport in the canyon is tidally-modulated in the drier winter season and flood (river)-dominated in the wetter summer season. From the magnitude and temporal variation of sediment flux in the canyon with respect to the burial flux and sediment budget on the open shelf and slope region, we reaffirm that, on annual or longer timescales, the Gaoping submarine canyon is an effective conduit transporting sediments from the Gaoping River's drainage basin (the source) to the deep South China Sea (the ultimate sink). ?? 2009 Elsevier B.V.

Historical reconstruction of atmospheric lead pollution in central Yunnan province, southwest China: an analysis based on lacustrine sedimentary records.

PubMed

Liu, Enfeng; Zhang, Enlou; Li, Kai; Nath, Bibhash; Li, Yanling; Shen, Ji

2013-12-01

Atmospheric lead (Pb) pollution during the last century in central Yunnan province, one of the largest non-ferrous metal production centers in China, was reconstructed using sediment cores collected from Fuxian and Qingshui Lakes. Lead concentrations and isotopic ratios ((207)Pb/(206)Pb and (208)Pb/(206)Pb) were measured in sediment cores from both lakes. The operationally defined chemical fractions of Pb in sediment core from Fuxian Lake were determined by the optimized BCR procedure. The chronology of the cores was reconstructed using (210)Pb and (137)Cs dating methods. Similar three-phase variations in isotopic ratios and enrichment factors of Pb were observed in the sediment cores from both lakes. Before the 1950s, the sediment data showed low (207)Pb/(206)Pb and (208)Pb/(206)Pb ratios and enrichment factors (EFs=~1), indicating that the sedimentary Pb was predominantly of lithogenic origin. However, these indices were increased gradually between the 1950s and the mid-1980s, implying an atmospheric Pb deposition. The EFs and isotopic ratios of Pb reached their peak during recent years, indicating aggravating atmospheric Pb pollution. The average anthropogenic Pb fluxes since the mid-1980s were estimated to be 0.032 and 0.053 g m(-2) year(-1) recorded in Fuxian and Qingshui cores, respectively. The anthropogenic Pb was primarily concentrated in the reducible fraction. Combining the results of Pb isotopic compositions and chemical speciations in the sediment cores and in potential sources, we deduced that recent aggravating atmospheric Pb pollution in central Yunnan province should primarily be attributed to regional emissions from non-ferrous metal production industries.

Anthropogenic Sources of Arsenic and Copper to Sediments of a Suburban Lake, 1964-1998

NASA Astrophysics Data System (ADS)

Rice, K. C.; Conko, K. M.; Hornberger, G. M.

2002-05-01

Nonpoint-source pollution from urbanization is becoming a widespread problem. Long-term monitoring data are necessary to document geochemical processes in urban settings and changes in sources of chemical contaminants over time. In the absence of long-term data, lake-sediment cores can be used to reconstruct past processes, because they serve as integrators of sources of pollutants from the contributing airshed and catchment. Lake Anne is a 10.9-ha man-made lake in a 235-ha suburban catchment in Reston, Virginia, with a population density of 1,116 people/km2. Three sediment cores, collected in 1996 and 1997, indicate increasing concentrations of arsenic and copper since 1964, when the lake was formed. The cores were compared to a core collected from a forested catchment in the same airshed that showed no increases in concentrations of these elements. Neither an increase in atmospheric deposition nor diagenesis and remobilization were responsible for the trends in the Lake Anne cores. Mass balances of sediment, arsenic, and copper were calculated using 1998 data on precipitation, streamwater, road runoff, and a laboratory leaching experiment on pressure-treated lumber. Sources of arsenic to the lake in 1998 were in-lake leaching of pressure-treated lumber (52%) and streamwater (47%). Road runoff was a greater (93%) source of copper than leaching of pressure-treated lumber (4%). Atmospheric deposition was an insignificant source (<3%) of both elements. Urbanization of the catchment was confirmed as a major cause of the increasing arsenic and copper in the lake cores through an annual historical reconstruction of the deposition of sediment, arsenic, and copper to the lake for 1964-1997. Aerial photography indicated that the area of roads and parking lots in the catchment increased to 26% by 1997 and that the number of docks on the lake also increased over time. The increased mass of arsenic and copper in the lake sediments corresponded to the increased amount of pressure-treated lumber in the lake, and the mass of copper also corresponded to the increase in paved surfaces in the catchment.

Sediment data collected in 2012 from the northern Chandeleur Islands, Louisiana

USGS Publications Warehouse

Bernier, Julie C.; Kelso, Kyle W.; Buster, Noreen A.; Flocks, James G.; Miselis, Jennifer L.; DeWitt, Nancy T.

2014-01-01

As part of the Barrier Island Evolution Research project, scientists from the U.S. Geological Survey St. Petersburg Coastal and Marine Science Center collected sediment samples from the northern Chandeleur Islands in March and September 2012. The overall objective of this project, which integrates geophysical (bathymetric, seismic, and topographic) and sedimentologic data, is to better understand the depositional and erosional processes that drive the morphologic evolution of barrier islands over annual to interannual timescales (1 to 5 years). Between June 2010 and April 2011, in response to the Deepwater Horizon oil spill, the State of Louisiana constructed a sand berm extending more than 14 kilometers along the northern Chandeleur Islands platform. The construction of the berm provided a unique opportunity to investigate how this new sediment source will interact with and affect the morphologic evolution of the barrier-island system. Data collected from this study will be used to describe differences in the physical characteristics and spatial distribution of sediments both along the axis of the berm and also along transects across the berm and onto the adjacent barrier island. Comparison of these data with data from subsequent sampling efforts will provide information about sediment interactions and movement between the berm and the natural island platform, improving our understanding of short-term morphologic change and processes in this barrier-island system. This data series serves as an archive of sediment data collected in March and September 2012 from the Chandeleur Islands sand berm and adjacent barrier-island environments. Data products include descriptive core logs, core photographs and x-radiographs, results of sediment grain-size analyses, sample location maps, and Geographic Information System data files with accompanying formal Federal Geographic Data Committee metadata.

The impacts of tracer selection and corrections for organic matter and particle size on the results of quantitative sediment fingerprinting. A case study from the Nene basin, UK.

NASA Astrophysics Data System (ADS)

Pulley, Simon; Ian, Foster; Paula, Antunes

2014-05-01

In recent years, sediment fingerprinting methodologies have gained widespread adoption when tracing sediment provenance in geomorphological research. A wide variety of tracers have been employed in the published literature, with corrections for particle size and organic matter applied when the researcher judged them necessary. This paper aims to explore the errors associated with tracer use by a comparison of fingerprinting results obtained using fallout and lithogenic radionuclides, geochemical, and mineral magnetic tracers in a range of environments located in the Nene basin, UK. Specifically, fingerprinting was undertaken on lake, reservoir and floodplain sediment cores, on actively transported suspended sediment and on overbank and channel bed sediment deposits. Tracer groups were investigated both alone and in combination to determine the differences between their sediment provenance predictions and potential causes of these differences. Additionally, simple organic and particle size corrections were applied to determine if they improve the agreement between the tracer group predictions. Key results showed that when fingerprinting contributions from channel banks to actively transported or recently deposited sediments the tracer group predictions varied by 24% on average. These differences could not be clearly attributed to changes in the sediment during erosion or transport. Instead, the most likely cause of differences was the pre-existing spatial variability in tracer concentrations within sediment sources, combined with highly localised erosion. This resulted in the collected sediment source samples not being representative of the actual sediment sources. Average differences in provenance predictions between the different tracer groups in lake, reservoir and floodplain sediment cores were lowest in the reservoir core at 19% and highest in some floodplain cores, with differences in predictions in excess of 50%. In these latter samples organic enrichment of the sediment, selective transport of fine particles and post-depositional chemical changes to the sediment were determined to be the likely cause of the differences. It was determined that organic and particle size corrections made the differences between tracer groups larger in most cases, although differences between tracer group predictions were reduced in two of the four floodplain cores.

Lake Michigan sediment lead storage and history of loads

EPA Science Inventory

Dated sediment box cores collected in 1994-1996 from 52 locations in Lake Michigan were analyzed for to access storage, trends, and loading history of lead. The results of this study provide information of historic lead loads to the lake for a time period for which no other info...

Historical trace element accumulation in marine sediments from the Tamaulipas shelf, Gulf of Mexico: An assessment of natural vs anthropogenic inputs.

PubMed

Celis-Hernandez, Omar; Rosales-Hoz, Leticia; Cundy, Andrew B; Carranza-Edwards, Arturo; Croudace, Ian W; Hernandez-Hernandez, Hector

2018-05-01

The Gulf of Mexico is considered one of the world's major marine ecosystems, supporting important fisheries and habitats such as barrier islands, mangrove forests, seagrass beds, coral reefs etc. It also hosts a range of complex offshore petroleum exploration, extraction, and refining industries, which may have chronic or acute impacts on ecosystem functioning. Previous work on the marine effects of this activity is geographically incomplete, and has tended to focus on direct hydrocarbon impacts, while impacts from other related contaminants (e.g. heavy metals, salt-rich drilling muds) which may be discharged from oil facilities have not been widely assessed. Here, we examine historical trace element accumulation in marine sediments collected from four sites in the Tamaulipas shelf, Gulf of Mexico, in the area of the Arenque oil field. Dated sediment cores were used to examine the sources, and historical and contemporary inputs, of trace metals (including those typically present in oil industry discharges) and their potential biological impact in the Tamaulipas aquatic environment over the last 100years. CaO (i.e. biogenic component) normalized data showed increasing V, Cr, Zn, Cu, Pb, Zr and Ba towards the sediment surface in three of the four cores, with Ba and V (based on an adverse effect index) possibly associated with adverse effects on organisms. Dated Ba/CaO profiles show an increase of 30-137% after opening of oil installations in the study area, and can be broadly correlated with increasing oil industry activities across the wider Gulf of Mexico. Data do not record however a clear enhancement of Ba concentration in sediment cores collected near to oil platforms over more distal cores, indicating that any Ba released from drilling platforms is incorporated quickly into the sediments around the drilling sites, and once this element has been deposited its rate of resuspension and mobility is low. Sediment core data from the Tamaulipas shelf show the influence of oil industry activities on selected trace element concentrations, with Ba/CaO broadly correlating with increasing oil industry activities across the wider Gulf of Mexico. Copyright © 2017 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chapelle, F.H.; Zelibor, J.L. Jr.; Grimes, D.J.

Nineteen cores of unconsolidated Coastal Plain sediments obtained from depths of 14 to 182 m below land surface near Waldorf, Maryland, were collected and examined for metabolically active bacteria. The age of the sediments cored range from Miocene to Early Cretaceous. Acridine orange direct counts of total (viable and nonviable) bacteria in core subsamples ranged from 10/sup 8/ to 10/sup 4/ bacteria/g of dry sediment. Direct counts of viable bacteria ranged from 10/sup 6/ to 10/sup 3/ bacteria/g of dry sediment. Three cores contained viable methanogenic bacteria, and seven cores contained viable sulfate-reducing bacteria. The observed presence of bacteria inmore » these sediments suggest that hetrotrophic bacterial metabolism, with lignitic organic material as the primary substrate, is a plausible source of CO/sub 2/ to ground water. However, the possibility that abiotic processes also produce CO/sub 2/ cannot be rules out. Estimated rates of CO/sub 2/ production in the noncalcareous Magothy/Upper Patapsco and Lower Patapsco aquifers based on mass balance of dissolved inorganic carbon, ground water flow rates, and flow path segment lengths are in the range 10/sup -3/ to 10/sup -5/ mmol L/sup -1/ yr/sup -1/. Isotope balance calculations suggest that aquifer-generated CO/sub 2/ is much heavier isotopically ( approx. - 10 to + 5 per mil) than lignite ( approx. - 24 per mil) present in these sediments. This may reflect isotopic fractionation during methanogenesis and possibly other bacterially mediated processes.« less

The Hominin Sites and Paleolakes Drilling Project: inferring the environmental context of human evolution from eastern African rift lake deposits

NASA Astrophysics Data System (ADS)

Cohen, A.; Campisano, C.; Arrowsmith, R.; Asrat, A.; Behrensmeyer, A. K.; Deino, A.; Feibel, C.; Hill, A.; Johnson, R.; Kingston, J.; Lamb, H.; Lowenstein, T.; Noren, A.; Olago, D.; Owen, R. B.; Potts, R.; Reed, K.; Renaut, R.; Schäbitz, F.; Tiercelin, J.-J.; Trauth, M. H.; Wynn, J.; Ivory, S.; Brady, K.; O'Grady, R.; Rodysill, J.; Githiri, J.; Russell, J.; Foerster, V.; Dommain, R.; Rucina, S.; Deocampo, D.; Russell, J.; Billingsley, A.; Beck, C.; Dorenbeck, G.; Dullo, L.; Feary, D.; Garello, D.; Gromig, R.; Johnson, T.; Junginger, A.; Karanja, M.; Kimburi, E.; Mbuthia, A.; McCartney, T.; McNulty, E.; Muiruri, V.; Nambiro, E.; Negash, E. W.; Njagi, D.; Wilson, J. N.; Rabideaux, N.; Raub, T.; Sier, M. J.; Smith, P.; Urban, J.; Warren, M.; Yadeta, M.; Yost, C.; Zinaye, B.

2016-02-01

The role that climate and environmental history may have played in influencing human evolution has been the focus of considerable interest and controversy among paleoanthropologists for decades. Prior attempts to understand the environmental history side of this equation have centered around the study of outcrop sediments and fossils adjacent to where fossil hominins (ancestors or close relatives of modern humans) are found, or from the study of deep sea drill cores. However, outcrop sediments are often highly weathered and thus are unsuitable for some types of paleoclimatic records, and deep sea core records come from long distances away from the actual fossil and stone tool remains. The Hominin Sites and Paleolakes Drilling Project (HSPDP) was developed to address these issues. The project has focused its efforts on the eastern African Rift Valley, where much of the evidence for early hominins has been recovered. We have collected about 2 km of sediment drill core from six basins in Kenya and Ethiopia, in lake deposits immediately adjacent to important fossil hominin and archaeological sites. Collectively these cores cover in time many of the key transitions and critical intervals in human evolutionary history over the last 4 Ma, such as the earliest stone tools, the origin of our own genus Homo, and the earliest anatomically modern Homo sapiens. Here we document the initial field, physical property, and core description results of the 2012-2014 HSPDP coring campaign.

Hydrologic Data for Deep Creek Lake and Selected Tributaries, Garrett County, Maryland, 2007-08

USGS Publications Warehouse

Banks, William S.L.; Davies, William J.; Gellis, Allen C.; LaMotte, Andrew E.; McPherson, Wendy S.; Soeder, Daniel J.

2010-01-01

Introduction Recent and ongoing efforts to develop the land in the area around Deep Creek Lake, Garrett County, Maryland, are expected to change the volume of sediment moving toward and into the lake, as well as impact the water quality of the lake and its many tributaries. With increased development, there is an associated increased demand for groundwater and surface-water withdrawals, as well as boat access. Proposed dredging of the lake bottom to improve boat access has raised concerns about the adverse environmental effects such activities would have on the lake. The Maryland Department of Natural Resources (MDDNR) and the U.S. Geological Survey (USGS) entered into a cooperative study during 2007 and 2008 to address these issues. This study was designed to address several objectives to support MDDNR?s management strategy for Deep Creek Lake. The objectives of this study were to: Determine the current physical shape of the lake through bathymetric surveys; Initiate flow and sediment monitoring of selected tributaries to characterize the stream discharge and sediment load of lake inflows; Determine sedimentation rates using isotope analysis of sediment cores; Characterize the degree of hydraulic connection between the lake and adjacent aquifer systems; and Develop an estimate of water use around Deep Creek Lake. Summary of Activities Data were collected in Deep Creek Lake and in selected tributaries from September 2007 through September 2008. The methods of investigation are presented here and all data have been archived according to USGS policy for future use. The material presented in this report is intended to provide resource managers and policy makers with a broad understanding of the bathymetry, surface water, sedimentation rates, groundwater, and water use in the study area. The report is structured so that the reader can access each topic separately using any hypertext markup (HTML) language reader. In order to establish a base-line water-depth map of Deep Creek Lake, a bathymetric survey of the lake bottom was conducted in 2007. The data collected were used to generate a bathymetric map depicting depth to the lake bottom from a full pool elevation of 2,462 feet (National Geodetic Vertical Datum of 1929). Data were collected along about 90 linear miles across the lake using a fathometer and a differentially corrected global positioning system. As part of a long-term monitoring plan for all surface-water inputs to the lake, streamflow data were collected continuously at two stations constructed on Poland Run and Cherry Creek. The sites were selected to represent areas of the watershed under active development and areas that are relatively stable with respect to development. Twelve months of discharge data are provided for both streams. In addition, five water-quality parameters were collected continuously at the Poland Run station including pH, specific conductance, temperature, dissolved oxygen, and turbidity. Water samples collected at Poland Run were analyzed for sediment concentration, and the results of this analysis were used to estimate the annual sediment load into Deep Creek Lake from Poland Run. To determine sedimentation rates, cores of lake-bottom sediments were collected at 23 locations. Five of the cores were analyzed using a radiometric-dating method, allowing average rates of sedimentation to be estimated for the time periods 1925 to 2008, 1925 to 1963, and 1963 to 2008. Particle-size data from seven cores collected at locations throughout the study area were analyzed to provide information on the amount of fine material in lake-bed sediments. Groundwater levels were monitored continuously in four wells and weekly in nine additional wells during October, November, and December of 2008. Water levels were compared to recorded lake levels and precipitation during the same period to determine the effect of lake-level drawdown and recovery on the adjacent aquifer systems. Water use in the Deep Creek Lake wa

Fluxes to sediments underlying the Rainbow hydrothermal plume at 36°14‧N on the Mid-Atlantic Ridge

NASA Astrophysics Data System (ADS)

Cave, R. R.; German, C. R.; Thomson, J.; Nesbitt, R. W.

2002-06-01

A geochemical investigation has been conducted of a suite of four sediment cores collected from directly beneath the hydrothermal plume at distances of 2 to 25 km from the Rainbow hydrothermal field. As well as a large biogenic component (>80% CaCO3) these sediments record clear enrichments of the elements Fe, Cu, Mn, V, P, and As from hydrothermal plume fallout but only minor detrital background material. Systematic variations in the abundances of ;hydrothermal; elements are observed at increasing distance from the vent site, consistent with chemical evolution of the dispersing plume. Further, pronounced Ni and Cr enrichments at specific levels within each of the two cores collected from closest to the vent site are indicative of discrete episodes of additional input of ultrabasic material at these two near-field locations. Radiocarbon dating reveals mean Holocene accumulation rates for all four cores of 2.7 to 3.7 cm.kyr-1, with surface mixed layers 7 to 10+ cm thick, from which a history of deposition from the Rainbow hydrothermal plume can be deduced. Deposition from the plume supplies elements to the underlying sediments that are either directly hydrothermally sourced (e.g., Fe, Mn, Cu) or scavenged from seawater via the hydrothermal plume (e.g., V, P, As). Holocene fluxes into to the cores' surface mixed layers are presented which, typically, are an order of magnitude greater than ;background; authigenic fluxes from the open North Atlantic. One core, collected closest to the vent site, indicates that both the concentration and flux of hydrothermally derived material increased significantly at some point between 8 and 12 14C kyr ago; the preferred explanation is that this variation reflects the initiation/intensification of hydrothermal venting at the Rainbow hydrothermal field at this time-perhaps linked to some specific tectonic event in this fault-controlled hydrothermal setting.

Assessment of sediments in the riverine impoundments of national wildlife refuges in the Souris River Basin, North Dakota

USGS Publications Warehouse

Tangen, Brian A.; Laubhan, Murray K.; Gleason, Robert A.

2014-01-01

Accelerated sedimentation of reservoirs and riverine impoundments is a major concern throughout the United States. Sediments not only fill impoundments and reduce their effective life span, but they can reduce water quality by increasing turbidity and introducing harmful chemical constituents such as heavy metals, toxic elements, and nutrients. U.S. Fish and Wildlife Service national wildlife refuges in the north-central part of the United States have documented high amounts of sediment accretion in some wetlands that could negatively affect important aquatic habitats for migratory birds and other wetland-dependent wildlife. Therefore, information pertaining to sediment accumulation in refuge impoundments potentially is important to guide conservation planning, including future management actions of individual impoundments. Lands comprising Des Lacs, Upper Souris, and J. Clark Salyer National Wildlife Refuges, collectively known as the Souris River Basin refuges, encompass reaches of the Des Lacs and Souris Rivers of northwestern North Dakota. The riverine impoundments of the Souris River Basin refuges are vulnerable to sedimentation because of the construction of in-stream dams that interrupt and slow river flows and because of post-European settlement land-use changes that have increased the potential for soil erosion and transport to rivers. Information regarding sediments does not exist for these refuges, and U.S. Fish and Wildlife Service personnel have expressed interest in assessing refuge impoundments to support refuge management decisions. Sediment cores and surface sediment samples were collected from impoundments within Des Lacs, Upper Souris, and J. Clark Salyer National Wildlife Refuges during 2004–05. Cores were used to estimate sediment accretion rates using radioisotope (cesium-137 [137Cs], lead-210 [210Pb]) dating techniques. Sediment cores and surface samples were analyzed for a suite of elements and agrichemicals, respectively. Examination of core characteristics along the depth profile suggests that there has been regular sediment mixing and removal, as well as non-uniform sediment deposition with time. Estimated mean accretion rates based on the three methods of determination (two time markers for 137Cs, 210Pb) ranged from 0.22–0.35 centimeters per year, and approximately 70 percent of cores had less 137Cs than expected. Concentrations of sediment-associated elements generally were within reported reference ranges, and all agrichemicals analyzed were below detection limits. Results suggest that there does not appear to be widespread sediment accumulation in impoundments of the Souris River Basin refuges. In addition, there were no identifiable patterns among sedimentation rates from the upstream (Des Lacs, Upper Souris) to the downstream (J. Clark Salyer) refuges. There were, however, apparent upstream to downstream patterns of increased concentrations of some elements (for example, aluminum, boron, and vanadium) that may warrant further exploration. Future related monitoring and research efforts should focus on areas with high potential for sediment accumulation, such as upstream areas adjacent to dams, to identify potential sediment problems before they become too severe. Further, assessments of suspended sediments transported in the Des Lacs and Souris Rivers would augment interpretation of sedimentation data by identifying potential sediment sources and areas with the greatest potential for accumulation.

Sediment cores and chemistry for the Kootenai River White Sturgeon Habitat Restoration Project, Boundary County, Idaho

USGS Publications Warehouse

Barton, Gary J.; Weakland, Rhonda J.; Fosness, Ryan L.; Cox, Stephen E.; Williams, Marshall L.

2012-01-01

The Kootenai Tribe of Idaho, in cooperation with local, State, Federal, and Canadian agency co-managers and scientists, is assessing the feasibility of a Kootenai River habitat restoration project in Boundary County, Idaho. This project is oriented toward recovery of the endangered Kootenai River white sturgeon (Acipenser transmontanus) population, and simultaneously targets habitat-based recovery of other native river biota. Projects currently (2010) under consideration include modifying the channel and flood plain, installing in-stream structures, and creating wetlands to improve the physical and biological functions of the ecosystem. River restoration is a complex undertaking that requires a thorough understanding of the river. To assist in evaluating the feasibility of this endeavor, the U.S. Geological Survey collected and analyzed the physical and chemical nature of sediment cores collected at 24 locations in the river. Core depths ranged from 4.6 to 15.2 meters; 21 cores reached a depth of 15.2 meters. The sediment was screened for the presence of chemical constituents that could have harmful effects if released during restoration activities. The analysis shows that concentrations of harmful chemical constituents do not exceed guideline limits that were published by the U.S. Army Corps of Engineers in 2006.

Historical record of lead accumulation and source in the tidal flat of Haizhou Bay, Yellow Sea: Insights from lead isotopes.

PubMed

Zhang, Rui; Guan, Minglei; Shu, Yujie; Shen, Liya; Chen, Xixi; Zhang, Fan; Li, Tiegang

2016-05-15

In order to investigate the historical records of lead contamination and source in coastal region of Haizhou Bay, Yellow Sea, a sediment core was collected from tidal flat, dated by (210)Pb and (137)Cs. Lead and its stable isotopic ratios were determined. The profiles of enrichment factor (EF) and Pb isotope ratios showed increasing trend upward throughout the core, correlating closely with the experience of a rapid economic and industrial development of the catchment. According to Pb isotopic ratios, coal combustion emission mainly contributed to the Pb burden in sediments. Based on end-member model, coal combustion emission dominated anthropogenic Pb sources in recent decades contributing from 48% to 67% in sediment. And the contribution of leaded gasoline was lower than 20%. A stable increase of coal combustion source was found in sediment core, while the contribution of leaded gasoline had declined recently, with the phase-out of leaded gasoline in China. Copyright © 2016 Elsevier Ltd. All rights reserved.

Seasonal-Scale Sedimentology and Restoration Potential in a Diversion-Fed Coastal Louisiana Wetland

NASA Astrophysics Data System (ADS)

Keogh, M.; Kolker, A.

2016-02-01

Coastal Louisiana is threatened by high rates of subsidence and rapid land loss. One promising method to mitigate this land loss is to divert Mississippi River water into surrounding wetlands. This study examines the impacts of one such diversion. Completed in 2002, Davis Pond Freshwater Diversion is located approximately 35 river km upstream of New Orleans. Although initially designed and operated to reduce salinity levels in the interior marsh, the diversion also delivers sediment and nutrients to the subsiding wetland. As a result, new land has emerged adjacent to the Davis Pond outfall channel in recent years. Here we examine patterns of seasonal-scale sediment accumulation and retention in the marsh surrounding Davis Pond diversion. Twenty-two short (5-cm) sediment cores were collected in spring 2015 immediately following a 13-day experimental release of Mississippi River water through the diversion. During this time, discharge increased from a base flow of approximately 28 m3s-1 (1,000 ft3s-1) to an elevated flow of between 142 and 283 m3s-1 (5,000 and 10,000 ft3s-1), before returning to base flow. A second set of cores were collected in fall 2015 after a 6-month period of base flow. Sediment cores were analyzed for organic content, bulk density, and grain size. In addition, inventories of beryllium-7 were used to calculate seasonal-scale sediment accumulation and retention rates. This work leads to the development of a sediment budget for the Davis Pond area and determination of long-term sediment trapping rates. Davis Pond Freshwater Diversion is an understudied system that can provide a scalable model for coast-wide restoration projects critical to the protection of Gulf Coast communities.

Water and Sediment Quality in the Yukon River Basin, Alaska, During Water Year 2001

USGS Publications Warehouse

Schuster, Paul F.

2003-01-01

Overview -- This report contains water-quality and sediment-quality data from samples collected in the Yukon River Basin during water year 2001 (October 2000 through September 2001). A broad range of chemical and biological analyses from three sets of samples are presented. First, samples were collected throughout the year at five stations in the basin (three on the mainstem Yukon River, one each on the Tanana and Porcupine Rivers). Second, fecal indicators were measured on samples from drinking-water supplies collected near four villages. Third, sediment cores from five lakes throughout the Yukon Basin were sampled to reconstruct historic trends in the atmospheric deposition of trace elements and hydrophobic organic compounds.

Benthic macrofaunal colonization patterns and preservation of laminated sediments: Observations in an extreme coastal basin environment in the lower Gulf of California

NASA Astrophysics Data System (ADS)

Herguera, J.; Paull, C. K.; Anderson, K.; Gwiazda, R.; Lundsten, E. M.; Kundz, L.; Edwards, B. D.; McGann, M. L.

2012-12-01

New observations and cores obtained with the ROV Doc Ricketts operated from the RV/Western Flyer provide a glimpse into a macrofauna barren sea-floor where laminated sediments are known to accumulate on the sea-floor of Alfonso Basin. This basin, located north of La Paz Bay, Baja California, is known to be an important repository of laminated sediments due to a combination of the relatively high input of terrigenous sediments brought in by summer rains, a moderate to high export productivity from its surface waters, and the very low oxygen concentrations at depth bathed by tropical subsurface waters. These laminated sediments are unique repositories of paleoceanographic and paleoclimatic information for its very high resolution records of past conditions comparable to ice core, tree ring, coral and cave records although spanning continuously much further back in time. However, the paleoceanographic community rarely has had the opportunity to visualize the seafloor surface where these sediments are accumulating and examine the biological abundance patterns in these extreme environments. Here we will show results from ROV Doc Ricketts quantitative video transects providing benthic faunal abundance patterns on the seafloor in these highly oxygen depleted bottom waters. These observations are further compared with the underlying stratigraphy. A coring system carried on the ROV allowed us to replicate cores and to collect a transect of 5 closely spaced cores to evaluate the horizontal extent of the observed variability down-core. We will also show some preliminary results from x-radiographs showing the nature of the laminations and its sediment composition based on elemental analysis on organic carbon, carbonate and biogenic opal analysis. New XRF results from a box core will be used to calibrate its terrigenous components with the historical rainfall record and evaluate its potential to reconstruct summer precipitation patterns in this region.

Pollen and palynofacies analyses of Paleocene-Eocene Thermal Maximum sediments from the North American continental shelf

NASA Astrophysics Data System (ADS)

Willard, D. A.; Robinson, M. M.; Self-Trail, J. M.; Wandless, G. A.; Sluijs, A.

2014-12-01

Analyses of pollen and palynofacies from Paleocene-Eocene Thermal Maximum (PETM) sediments from three cores collected on the Atlantic Coastal Plain provide insights into the timing of vegetation and hydrologic changes associated with the PETM in eastern North America. The Mattawoman Creek-Billingsley Road (MCBR2), South Dover Bridge (SDB), and Bass River (ODP Site 1074AX) cores were collected at progressively greater distances from the paleoshoreline in continental shelf deposits in Maryland and New Jersey, USA. The PETM carbon isotope excursion (CIE) at each site is accompanied by sharp increases in pollen and spore concentrations, as well as changes in terrestrial palynomorph assemblage composition. In the two sites proximal to the paleoshoreline in Maryland, CIE fern spore abundance was two- to three times greater than in pre-CIE assemblages. At the distal site at Bass River, fern spores are present in CIE sediments and absent in pre-CIE sediments. Angiosperm pollen is most common in CIE sediments at all three sites. Palynofacies analyses, which quantify contributions of organic material from marine and non-marine sources, indicate that terrestrial influx increased sharply at the CIE onset. This observation is consistent with seasonally increased runoff from the continent.

Phosphorus fractionation and distribution in sediments from wetlands and canals of a water conservation area in the Florida Everglades

Treesearch

Qingren Wang; Yuncong Li; Ying Ouyang

2011-01-01

Phosphorus (P) fractionation and distribution in sediments are of great concern in the Florida Everglades ecosystem because potential eutrophication of surface waters usually results from P external loading and stability. Intact core sediment samples were collected to a depth of 35 cm from wetlands and canals across Water Conservation Area 3 (WCA‐3) of the Florida...

Decadal-scale sediment dynamics and environmental change in the Albemarle Estuarine System, North Carolina

NASA Astrophysics Data System (ADS)

Corbett, D. Reide; Vance, Dave; Letrick, Erin; Mallinson, David; Culver, Stephen

2007-02-01

During the summer of 2001, several short cores (<50 cm) were collected in the Albemarle Estuarine System (AES). Down-core measurements for radiochemical tracers ( 210Pb, 137Cs) and organic matter signatures (δ 13C, δ 15N, C:N ratio, and LOI) have been used to elucidate potential temporal changes in fluxes and cycles of organic matter in the AES. Pb-210 geochronology indicates temporal and spatial variations in sediment deposition rates (0.08-0.57 cm y -1) with highest rates near the AES western limit relative to the rest of the estuary. Low accumulation rates, deficient excess 210Pb inventories, and near linear 137Cs profiles throughout the AES suggest that sediments are resuspended by wind-generated waves and currents and flushed from the system by river discharge and wind-tides, probably to Pamlico Sound to the south. Sediments in the AES are accumulating at rates less than the current rate of relative sea-level rise for this region except in protected portions of the estuary. Thus sediment accumulation in the AES is controlled in the short term by storm wave-base and in the long term by the creation of accommodation space by basin subsidence and sea-level rise. The geochemical and sedimentological data characterize the evolution of the Albemarle Sound and associated tributaries over the past 200-300 years. The majority of cores collected throughout the system show a significant decrease in 13C and increase in 15N isotopic signatures up-core. Thus, the estuarine system of eastern North Carolina has changed from a marine-influenced, high brackish environment to the modern-day system, which is a highly variable, terrestrially influenced, low brackish environment.

Sediment accumulation and mixing in the Penobscot River and estuary, Maine.

PubMed

Yeager, K M; Schwehr, K A; Schindler, K J; Santschi, P H

2018-04-16

Mercury (Hg) was discharged in the late 1960s into the Penobscot River by the Holtra-Chem chlor-alkali production facility, which was in operation from 1967 to 2000. To assess the transport and distribution of total Hg, and recovery of the river and estuary system from Hg pollution, physical and radiochemical data were assembled from sediment cores collected from 58 of 72 coring stations sampled in 2009. These stations were located throughout the lower Penobscot River, and included four principal study regions, the Penobscot River (PBR), Mendall Marsh (MM), the Orland River (OR), and the Penobscot estuary (ES). To provide the geochronology required to evaluate sedimentary total Hg profiles, 58 of 72 sediment cores were dated using the atmospheric radionuclide tracers 137 Cs, 210 Pb, and 239,240 Pu. Sediment cores were assessed for depths of mixing, and for the determination of sediment accumulation rates using both geochemical (total Hg) and radiochemical data. At most stations, evidence for significant vertical mixing, derived from profiles of 7 Be (where possible) and porosity, was restricted to the upper ~1-3cm. Thus, historic profiles of both total Hg and radionuclides were only minimally distorted, allowing a reconstruction of their depositional history. The pulse input tracers 137 Cs and 239,240 Pu used to assess sediment accumulation rates agreed well, while the steady state tracer 210 Pb exhibited weaker agreement, likely due to irregular lateral sediment inputs. Copyright © 2018. Published by Elsevier B.V.

Head-of-tide bottleneck of particulate material transport from watersheds to estuaries

NASA Astrophysics Data System (ADS)

Ensign, Scott H.; Noe, Gregory B.; Hupp, Cliff R.; Skalak, Katherine J.

2015-12-01

We measured rates of sediment, C, N, and P accumulation at four floodplain sites spanning the nontidal through oligohaline Choptank and Pocomoke Rivers, Maryland, USA. Ceramic tiles were used to collect sediment for a year and sediment cores were collected to derive decadal sedimentation rates using 137Cs. The results showed highest rates of short- and long-term sediment, C, N, and P accumulation occurred in tidal freshwater forests at the head of tide on the Choptank and the oligohaline marsh of the Pocomoke River, and lowest rates occurred in the downstream tidal freshwater forests in both rivers. Presumably, watershed material was mostly trapped at the head of tide, and estuarine material was trapped in oligohaline marshes. This hydrologic transport bottleneck at the head of tide stores most available watershed sediment, C, N, and P creating a sediment shadow in lower tidal freshwater forests potentially limiting their resilience to sea level rise.

Head-of-tide bottleneck of particulate material transport from watersheds to estuaries

USGS Publications Warehouse

Ensign, Scott H.; Noe, Gregory; Hupp, Cliff R.; Skalak, Katherine

2015-01-01

We measured rates of sediment, C, N, and P accumulation at four floodplain sites spanning the nontidal through oligohaline Choptank and Pocomoke Rivers, Maryland, USA. Ceramic tiles were used to collect sediment for a year and sediment cores were collected to derive decadal sedimentation rates using 137Cs. The results showed highest rates of short- and long-term sediment, C, N, and P accumulation occurred in tidal freshwater forests at the head of tide on the Choptank and the oligohaline marsh of the Pocomoke River, and lowest rates occurred in the downstream tidal freshwater forests in both rivers. Presumably, watershed material was mostly trapped at the head of tide, and estuarine material was trapped in oligohaline marshes. This hydrologic transport bottleneck at the head of tide stores most available watershed sediment, C, N, and P creating a sediment shadow in lower tidal freshwater forests potentially limiting their resilience to sea level rise.

Spatial and Vertical Distribution of Dechlorane Plus in Mangrove Sediments of the Pearl River Estuary, South China.

PubMed

Sun, Yu-Xin; Zhang, Zai-Wang; Xu, Xiang-Rong; Hao, Qin-Wei; Hu, Yong-Xia; Zheng, Xiao-Bo; Luo, Xiao-Jun; Diao, Zeng-Hui; Mai, Bi-Xian

2016-10-01

Thirty surface sediments and three sediment cores were collected from mangrove wetlands in the Pearl River Estuary of South China to investigate the spatial and vertical distribution of Dechlorane Plus (DP). DP concentrations in the mangrove surface sediments ranged from 0.0130 to 1.504 ng/g dry weight (dw). DP concentrations in sediments from Shenzhen were significantly greater than those from Guangzhou and Zhuhai. Anti-Cl11-DP, the dechlorinated product of anti-DP, was also detected in the mangrove sediments with concentrations ranged from not detected to 0.0198 ng/g dw. Significant positive relationship between anti-Cl11-DP and anti-DP levels was observed in the mangrove sediments, suggesting that photo and/or microbial degradation of anti-DP might occur in the sediments. The f anti values in the mangrove sediments were close to those in the technical DP products, suggesting that stereoselective enrichment of anti-DP may not exist in the mangrove sediments. DP concentrations in the mangrove sediment cores generally showed an increasing trend from the bottom to top layers. This is the first study to report the occurrence of DP and its degradation product in the mangrove wetlands.

Lake Worth bottom sediments : A chronicle of water-quality changes in western Fort Worth, Texas, 1914-2001

USGS Publications Warehouse

Braun, Christopher L.; Harwell, Glenn R.

2004-01-01

In spring 2000, the Texas Department of Health issued a fish-consumption advisory for Lake Worth, Tex., because of elevated concentrations of polychlorinated biphenyls (PCBs) in fish (Texas Department of Health, 2000). In response to the advisory and in cooperation with the U.S. Air Force, the U.S. Geological Survey (USGS) collected 21 surficial samples and three deeper gravity core samples from the sediment deposited at the bottom of Lake Worth. The purpose of that study was to assess the spatial distribution and historical trends of selected hydrophobic contaminants, including PCBs, and to determine, to the extent possible, sources of selected metals and hydrophobic organic contaminants (HOCs) to Lake Worth. Hydrophobic (literally “water fearing”) contaminants tend to chemically adsorb to soils and sediments. Fifteen of the top 20 contaminants on the Agency for Toxic Substances and Disease Registry (2001) priority list of hazardous substances are hydrophobic. Chemical analysis of sediment cores is one method that can be used to determine trends in HOCs such as PCBs. As sediments accumulate in lakes and reservoirs, they generate a partial historical record of water quality. This fact sheet describes the collection of sediment cores, age-dating methods, and historical trends in PCBs in Lake Worth sediments. The fact sheet also describes the spatial distribution of PCBs in surficial sediments and concludes with objectives for the second phase of data collection and the approach that will be used to achieve these objectives. The USGS published a comprehensive report on the first phase of the study (Harwell and others, 2003). Lake Worth is a reservoir on the West Fork Trinity River on the western edge of Fort Worth in Tarrant County. In 1914, the City of Fort Worth completed the reservoir to serve as a municipal water supply. Lake Worth has a surface area of 13.2 square kilometers and a storage capacity of 47 million cubic meters. The drainage area to the reservoir is 5,350 square kilometers(Ruddy and Hitt, 1990). The surrounding area to the south and east is primarily urban, and the area to the north and northwest is mostly residential.

Investigation of Total and Methyl Mercury in Fish and Sediment of Lake Michigan

EPA Science Inventory

Sediment cores and fish collected between 1994 and 1996 as part of the Lake Michigan Mass Balance Project were analyzed for total and methyl mercury. Results of the fish analyses are being used to describe total and methyl mercury concentrations in forage fish and lake trout, re...

Protocol to Reconstruct Historical Contaminant Loading to Large Lakes: The Lake Michigan Sediment Record of Mercury

EPA Science Inventory

Samples of opportunity from Pb-210 dated sediment cores collected from Lake Michigan between 1994 and 1996 were analyzed for mercury. The storage of both anthropogenic and total (post-1850) mercury in the lake was calculated to be 186 and 228 metric tons, respectively. By setti...

Sedimentation and sediment chemistry, Neopit Mill Pond, Menominee Indian Reservation, Wisconsin, 2001

USGS Publications Warehouse

Fitzpatrick, Faith A.; Peppler, Marie C.

2003-01-01

The volume, texture, and chemistry of sediment deposited in a mill pond on the West Branch of the Wolf River at Neopit, Wis., Menominee Reservation, were studied in 2001-2002. The study was accomplished by examining General Land Office Survey Notes from 1854, establishing 12 transects through the mill pond, conducting soundings of the soft and hard bottom along each transect, and collecting core samples for preliminary screening of potential contaminants. Combined information from transects, cores, and General Land Office Survey notes were used to reconstruct the pre-dam location of the West Branch of the Wolf River through the mill pond. Neopit Mill Pond contains approximately 253 acre-ft of organic-rich muck, on average about 1.2 ft thick, that was deposited after the dam was built. Elevated concentrations of polycyclic aromatic hydrocarbons (PAHs) associated with creosote and pentachlorophenol were found in post-dam sediment samples collected from Neopit Mill Pond. Trace-element concentrations were at or near background concentrations. Further study and sampling are needed to identify the spatial extent and variability of the PAHs, pentachlorophenol, and other byproducts from wood preservatives

Coastal circulation and sediment dynamics in Hanalei Bay, Kaua'i, Hawaii: Part II: tracking recent fluvial sedimentation; isotope stratigraphy obtained in Summer 2005

USGS Publications Warehouse

Draut, Amy E.; Field, Michael E.; Bothner, Michael H.; Logan, Joshua B.; Casso, Michael A.; Baldwin, Sandra M.; Storlazzi, Curt D.

2006-01-01

Delivery and dispersal of fluvial sediment in Hanalei Bay, Kaua’i, Hawaii, have important implications for the health of local coral reefs. The reef community in Hanalei Bay represents a relatively healthy ecosystem. However, the reefs are periodically stressed by storm waves, and increases in sediment and dissolved substances from the Hanalei River have the potential to cause additional stress. Increased turbidity and sedimentation on corals during Hanalei River floods that occur in seasons of low wave energy, when sediment would not be readily remobilized and advected out of the bay, could affect the health and sustainability of coral reefs and the many associated species. Measurements of short-lived isotopes 7Be and 137Cs in sediment cores have been used to trace the thickness and distribution of terrestrial sediment in Hanalei Bay, in order to assess spatial and temporal patterns of sediment deposition and remobilization relative to coral-reef locations. A third isotope, 210Pb, derived primarily from seawater, provides additional information about recent sedimentary history. Isotope profiles and observations of sedimentary facies from cores collected at multiple locations in June 2005, and again in August 2005, indicate the presence of recent fluvial sediment and organic debris in the east part of the bay near the mouth of the Hanalei River. Away from the immediate vicinity of the river mouth, sediment in the uppermost 1 m below the sea floor had not retained a significant quantity of fluvial sediment within the eight months prior to either sampling effort. During the study interval in summer 2005 the Hanalei River had no major floods and there was relatively little sediment input to the bay. Sediment away from the river mouth was dominated by carbonate sand, although some terrestrial sediment was present in sub-sea-floor horizons. Sedimentary facies and isotope inventories throughout the bay showed substantial spatial heterogeneity. Sediment cores will be collected again at the same sites discussed here during early and late summer 2006. If possible, additional sites will be sampled in the Black Hole depocenter near the river mouth. Major floods in winter and spring 2006 are expected to leave a significant new sediment signal in the bay that should be detected in summer 2006.

Mercury accumulation and attenuation at a rapidly forming delta with a point source of mining waste

PubMed Central

Johnson, Bryce E.; Esser, Bradley K.; Whyte, Dyan C.; Ganguli, Priya M.; Austin, Carrie M.; Hunt, James R.

2009-01-01

The Walker Creek intertidal delta of Tomales Bay, California is impacted by a former mercury mine within the watershed. Eleven short sediment cores (10 cm length) collected from the delta found monomethylmercury (MMHg) concentrations ranging from 0.3 to 11.4 ng/g (dry wt.), with lower concentrations occurring at the vegetated marsh and upstream channel locations. Algal mats common to the delta’s sediment surface had MMHg concentrations ranging from 7.5 to 31.5 ng/g, and the top 1 cm of sediment directly under the mats had two times greater MMHg concentrations compared to adjacent locations without algal covering. Spatial trends in resident biota reflect enhanced MMHg uptake at the delta compared to other bay locations. Eighteen sediment cores, 1 to 2 meters deep, collected from the 1.2 km2 delta provide an estimate of a total mercury (Hg) inventory of 2500 ± 500 kg. Sediment Hg concentrations ranged from pre-mining background conditions of approximately 0.1 μg/g to a post-mining maximum of 5 μg/g. Sediment accumulation rates were determined from three sediment cores using measured differences of 137Cs activity. We estimate a pre-mining Hg accumulation of less than 20 kg/yr, and a period of maximum Hg accumulation in the 1970s and 1980s with loading rates greater than 50 kg/yr, corresponding to the failure of a tailings dam at the mine site. At the time of sampling (2003) over 40 kg/yr of Hg was still accumulating at the delta, indicating limited recovery. We attribute observed spatial evolution of elevated Hg levels to ongoing inputs and sediment re-working, and estimate the inventory of the anthropogenic fraction of total Hg to be at least 1500 ± 300 kg. We suggest ongoing sediment inputs and methylation at the deltaic surface support enhanced mercury levels for resident biota and transfer to higher trophic levels throughout the Bay. PMID:19539980

Dating of sediment record at two contrasting sites of the Seine River using radioactivity data and hydrological time series.

PubMed

Vrel, Anne; Boust, Dominique; Lesueur, Patrick; Deloffre, Julien; Dubrulle-Brunaud, Carole; Solier, Luc; Rozet, Marianne; Thouroude, Coralie; Cossonnet, Catherine; Thomas, Sandrine

2013-12-01

Sediment cores were collected at the outlet of the highly anthropogenized catchment of the Seine River at two contrasting sites: a flood plain of the lower Seine River and a quasi-permanently submerged harbour basin (or wet dock) in the upper tidal estuary. Analyses of artificial radionuclides ((137)Cs and plutonium isotopes), coupled with hydrological and bathymetric data, lead to a precise dating of the sediment cores collected at the two sites. (137)Cs signals originating from global fallout (early 1960s) and from the Chernobyl accident (1986) are identified, but at different levels due to the incomplete nature or variable continuity of the records. Anomalous (238)Pu concentrations found at both sites (1-2 Bq kg(-1)) are attributed to unknown industrial releases originating from upstream. Interpolating (137)Cs sediment activities under the assumption of a constant sediment rate, those releases were dated back to 1975 ± 1, thus providing a local but reliable time-marker. Age models have highlighted a very contrasting sediment filling dynamics in these two sites. This study presents the first sediment record of alpha- and gamma-emitting artificial radionuclides obtained at the outlet of the huge catchment area of the River Seine, over a period covering the last 50 years. Copyright © 2013 Elsevier Ltd. All rights reserved.

Drilling, construction, geophysical log data, and lithologic log for boreholes USGS 142 and USGS 142A, Idaho National Laboratory, Idaho

USGS Publications Warehouse

Twining, Brian V.; Hodges, Mary K.V.; Schusler, Kyle; Mudge, Christopher

2017-07-27

Starting in 2014, the U.S. Geological Survey in cooperation with the U.S. Department of Energy, drilled and constructed boreholes USGS 142 and USGS 142A for stratigraphic framework analyses and long-term groundwater monitoring of the eastern Snake River Plain aquifer at the Idaho National Laboratory in southeast Idaho. Borehole USGS 142 initially was cored to collect rock and sediment core, then re-drilled to complete construction as a screened water-level monitoring well. Borehole USGS 142A was drilled and constructed as a monitoring well after construction problems with borehole USGS 142 prevented access to upper 100 feet (ft) of the aquifer. Boreholes USGS 142 and USGS 142A are separated by about 30 ft and have similar geology and hydrologic characteristics. Groundwater was first measured near 530 feet below land surface (ft BLS) at both borehole locations. Water levels measured through piezometers, separated by almost 1,200 ft, in borehole USGS 142 indicate upward hydraulic gradients at this location. Following construction and data collection, screened water-level access lines were placed in boreholes USGS 142 and USGS 142A to allow for recurring water level measurements.Borehole USGS 142 was cored continuously, starting at the first basalt contact (about 4.9 ft BLS) to a depth of 1,880 ft BLS. Excluding surface sediment, recovery of basalt, rhyolite, and sediment core at borehole USGS 142 was approximately 89 percent or 1,666 ft of total core recovered. Based on visual inspection of core and geophysical data, material examined from 4.9 to 1,880 ft BLS in borehole USGS 142 consists of approximately 45 basalt flows, 16 significant sediment and (or) sedimentary rock layers, and rhyolite welded tuff. Rhyolite was encountered at approximately 1,396 ft BLS. Sediment layers comprise a large percentage of the borehole between 739 and 1,396 ft BLS with grain sizes ranging from clay and silt to cobble size. Sedimentary rock layers had calcite cement. Basalt flows ranged in thickness from about 2 to 100 ft and varied from highly fractured to dense, and ranged from massive to diktytaxitic to scoriaceous, in texture.Geophysical logs were collected on completion of drilling at boreholes USGS 142 and USGS 142A. Geophysical logs were examined with available core material to describe basalt, sediment and sedimentary rock layers, and rhyolite. Natural gamma logs were used to confirm sediment layer thickness and location; neutron logs were used to examine basalt flow units and changes in hydrogen content; gamma-gamma density logs were used to describe general changes in rock properties; and temperature logs were used to understand hydraulic gradients for deeper sections of borehole USGS 142. Gyroscopic deviation was measured to record deviation from true vertical at all depths in boreholes USGS 142 and USGS 142A.

Tracing historical trends of Hg in the Mississippi River using Hg concentrations and Hg isotopic compositions in a lake sediment core, Lake Whittington, Mississippi, USA

USGS Publications Warehouse

Gray, John E.; Van Metre, Peter C.; Pribil, Michael J.; Horowitz, Arthur J.

2015-01-01

Concentrations and isotopic compositions of mercury (Hg) in a sediment core collected from Lake Whittington, an oxbow lake on the Lower Mississippi River, were used to evaluate historical sources of Hg in the Mississippi River basin. Sediment Hg concentrations in the Lake Whittington core have a large 10-15 y peak centered on the 1960s, with a maximum enrichment factor relative to Hg in the core of 4.8 in 1966. The Hg concentration profile indicates a different Hg source history than seen in most historical reconstructions of Hg loading. The timing of the peak is consistent with large releases of Hg from Oak Ridge National Laboratory (ORNL), primarily in the late 1950s and 1960s. Mercury was used in a lithiumisotope separation process by ORNL and an estimated 128Mg (megagrams) of Hgwas discharged to a local stream that flows into the Tennessee River and, eventually, the Mississippi River. Mass balance analyses of Hg concentrations and isotopic compositions in the Lake Whittington core fit a binary mixing model with a Hg-rich upstream source contributing about 70% of the Hg to Lake Whittington at the height of the Hg peak in 1966. This upstream Hg source is isotopically similar to Hg isotope compositions of stream sediment collected downstream near ORNL. It is estimated that about one-half of the Hg released from the ORNL potentially reached the LowerMississippi River basin in the 1960s, suggesting considerable downstream transport of Hg. It is also possible that upstream urban and industrial sources contributed some proportion of Hg to Lake Whittington in the 1960s and 1970s.

Synthetic Musk Fragrances in Lake Erie and Lake Ontario Sediment Cores

PubMed Central

Peck, Aaron M.; Linebaugh, Emily K.; Hornbuckle, Keri C.

2009-01-01

Two sediment cores collected from Lake Ontario and Lake Erie were sectioned, dated, and analyzed for five polycyclic musk fragrances and two nitro musk fragrances. The polycyclic musk fragrances were HHCB (Galaxolide), AHTN (Tonalide), ATII (Traseolide), ADBI (Celestolide), and AHMI (Phantolide). The nitro musk fragrances were musk ketone and musk xylene. Chemical analysis was performed by gas chromatography/mass spectrometry (GC/MS) and results from Lake Erie were confirmed using gas chromatography/triple-quadrupole mass spectrometry (GC/MS/MS). The chemical signals observed at the two sampling locations were different from each other due primarily to large differences in the sedimentation rates at the two sampling locations. HHCB was detected in the Lake Erie core while six compounds were detected in the Lake Ontario core. Using measured fragrance and 210Pb activity, the burden of synthetic musk fragrances estimated from these sediment cores is 1900 kg in Lake Erie and 18000 kg in Lake Ontario. The input of these compounds to the lakes is increasing. The HHCB accumulation rates in Lake Erie for 1979-2003 and 1990-2003 correspond to doubling times of 16 ± 4 yr and 8 ± 2 yr, respectively. The results reflect current U.S. production trends for the sum of all fragrance compounds. PMID:17007119

Mineralogical and Geochemical Analyses of Antarctic Lake Sediments: A Reflectance and Moessbauer Spectroscopy Study with Applications for Remote Sensing on Mars

NASA Technical Reports Server (NTRS)

Froeschl, Heinz; Lougear, Andre; Trautwein, Alfred X.; Newton, Jason; Doran, Peter T.; Koerner, Wilfried; Koeberl, Christian; Bishop, Janice (Technical Monitor); DeVincenzi, Donald L. (Technical Monitor)

2000-01-01

Lakebottom sediments from the Dry Valleys region of Antarctica have been analyzed here in order to study the influence of water chemistry on the mineralogy and geochemistry of these sediments, as well as to evaluate techniques for remote spectral identification of potential biomarker minerals on Mars. Lakes from the Dry Valleys region of Antarctica have been investigated as possible analogs for extinct lake environments on early Mars. Sediment cores were collected in the present study from perennially ice-covered Lake Hoare in the Taylor Valley. These sediments were taken from a core in an oxic region of the lake and another core in an anoxic zone. Differences between the two cores were observed in the sediment color, Fe(II)/Fe(III) ratio, the presence of pyrite, the abundance of Fe, S and some trace elements, and the C, N and S isotope fractionation patterns. The results of visible-infrared reflectance spectroscopy (0.3-25 microns) Mossbauer spectroscopy (77 and 4 K) and X-ray diffraction are combined to determine the mineralogy and composition of these samples. The sediments are dominated by plagioclase, K-feldspar, quartz and pyroxene. Algal mats grow on the bottom of the lake and organic material has been found throughout the cores. Calcite is abundant in some layers of the aerobic core (shallow region) and pyrite is abundant in some layers of the anaerobic core (deep region). Analysis of the spectroscopic features due to organics and carbonates with respect to the abundance of organic C and carbonate contents was performed in order to select optimal spectral bands for remote identification of these components in planetary regoliths. Carbonate bands near 4 and 6.8 microns (approx.2500 and 1500/cm) were detected for carbonate abundances as low as 0.1 wt.% CO2. Organic features at 3.38, 3.42 and 3.51 microns (2960, 2925 and 2850/cm) were detected for organic C abundances as low as 0.06 wt.% C. The d13C trends show a more complex organic history for the anaerobic sediments than for the aerobic sediments. The biogenic pyrite found in the anaerobic core is associated with lighter d34S values and high organic C levels and could be used as a biomarker mineral for paleolakes on Mars.

Sedimentological and geochemical investigations to understand source of sediments and processes of recent past in Schirmacher Oasis, East Antarctica

NASA Astrophysics Data System (ADS)

Choudhary, Shabnam; Tiwari, Anoop Kumar; Nayak, G. N.; Bejugam, Purnima

2018-03-01

Three sediment cores collected from GL-1, V-1(Vetehiya) and L-6 lakes of Schirmacher Oasis, East Antarctica were studied for sediment components (sand, silt, clay, total organic carbon, total nitrogen, TOC/TN ratio and biogenic silica), major elements (Aluminium, Iron and Manganese) and trace metals (Chromium, Zinc, Lead, Cobalt, Cadmium and Nickel). High sand content in all the three cores revealed the release of coarser sediments through mechanical weathering in fluvio-glacial environment. Relatively, high biogenic silica along with high total organic carbon associated with high clay in some sections indicated high primary productivity due to the warming and exposure of the lakes to the ice-melt water influx. TOC/TN ratio for all the cores was found to be < 10 which indicated that the major source of organic matter was autochthonous. Metals were found to be strongly associated with clay and organic carbon in core V-1, with sand and clay in core L-6 while, with silt and organic matter in core GL-1 indicating their role in regulating the distribution of metals. Cadmium in lake GL-1 was found to be associated with total organic carbon and showed largely biogenic origin, while, Cd and Pb in lakes L-6 and V-1 were found to be of anthropogenic origin. All the other metals showed signatures of lithogenic origin.

Sediment data collected in 2014 and 2015 from around Breton and Gosier Islands, Breton National Wildlife Refuge, Louisiana

USGS Publications Warehouse

Bernier, Julie C.; Kelso, Kyle W.; Tuten, Thomas M.; Stalk, Chelsea A.; Flocks, James G.

2017-03-08

Breton Island, located at the southern end of the Chandeleur Islands, supports one of Louisiana’s largest historical brown pelican (Pelecanus occidentalis) nesting colonies. Although the brown pelican was delisted as an endangered species in 2009, nesting areas are threatened by continued land loss and are extremely vulnerable to storm impacts. The U.S. Fish and Wildlife Service proposed to restore Breton Island to pre-Hurricane Katrina conditions through rebuilding the shoreface, dune, and back-barrier marsh environments. Prior to restoration, scientists from the U.S. Geological Survey’s (USGS) St. Petersburg Coastal and Marine Science Center Geologic and Morphologic Evolution of Coastal Margins project collected high-resolution geophysical (topography, bathymetry, and sub-bottom profiles) and sedimentologic data from around Breton Island to characterize the geologic framework of the island platform, nearshore, and shelf environments. These data will be used to characterize the geologic framework around Breton Island, identify potential borrow areas for restoration efforts, quantify seafloor change, and provide information for sediment transport and morphologic change models to assess island response to restoration and natural processes.This report, along with the accompanying USGS data release, serves as an archive of sediment data from vibracores, push cores, and submerged grab samples collected from around Breton and Gosier Islands, Louisiana, during two surveys conducted in July 2014 and January 2015 (USGS Field Activity Numbers 2014–314–FA and 2014–336–FA, respectively). Sedimentologic and stratigraphic metrics (for example, sediment texture or unit thicknesses) derived from these data can be used to ground-truth the geophysical data and characterize potential sand resources or can be incorporated into sediment transport or morphologic change models. Data products, including sample location tables, descriptive core logs, core photographs and x-radiographs, results of sediment grain-size analyses, and geographic information system data files with accompanying formal Federal Geographic Data Committee metadata can be downloaded from the accompanying data release.

Google Earth-Based Grand Tours of the World's Ocean Basins and Marine Sediments

NASA Astrophysics Data System (ADS)

St John, K. K.; De Paor, D. G.; Suranovic, B.; Robinson, C.; Firth, J. V.; Rand, C.

2016-12-01

The GEODE project has produced a collection of Google Earth-based marine geology teaching resources that offer grand tours of the world's ocean basins and marine sediments. We use a map of oceanic crustal ages from Müller et al (2008; doi:10.1029/2007GC001743), and a set of emergent COLLADA models of IODP drill core data as a basis for a Google Earth tour introducing students to the world's ocean basins. Most students are familiar with basic seafloor spreading patterns but teaching experience suggests that few students have an appreciation of the number of abandoned ocean basins on Earth. Students also lack a valid visualization of the west Pacific where the oldest crust forms an isolated triangular patch and the ocean floor becomes younger towards the subduction zones. Our tour links geographic locations to mechanical models of rifting, seafloor spreading, subduction, and transform faulting. Google Earth's built-in earthquake and volcano data are related to ocean floor patterns. Marine sediments are explored in a Google Earth tour that draws on exemplary IODP core samples of a range of sediment types (e.g., turbidites, diatom ooze). Information and links are used to connect location to sediment type. This tour compliments a physical core kit of core catcher sections that can be employed for classroom instruction (geode.net/marine-core-kit/). At a larger scale, we use data from IMLGS to explore the distribution of the marine sediments types in the modern global ocean. More than 2,500 sites are plotted with access to original data. Students are guided to compare modern "type sections" of primary marine sediment lithologies, as well as examine site transects to address questions of bathymetric setting, ocean circulation, chemistry (e.g., CCD), and bioproductivity as influences on modern seafloor sedimentation. KMZ files, student exercises, and tips for instructors are available at geode.net/exploring-marine-sediments-using-google-earth.

Temporal changes of environmental impact in the coastal marine area in front of a former mining zone, detected by means of benthic foraminifera

NASA Astrophysics Data System (ADS)

Romano, Elena; Bergamin, Luisa; Maggi, Chiara; Ausili, Antonella

2016-04-01

Benthic foraminifera are increasingly used to assess environmental quality of present and past marine environments. They are suitable for the study of ancient environments because their hard and small shells are preserved and abundant in sediment and an adequate number of them can be collected by small samples of sediment cores, supplying reliable data for a statistical approach. The study of foraminiferal assemblages, associated to sediment abiotic parameters, allows to define the anthropogenic impact along the time; reference conditions may be recognized in deep uncontaminated levels. The Sulcis Iglesiente Guspinese area (SW Sardinia, Italy) was affected in past times by intensive mining, which started in mid 19th century and ceased in 1990s. The marine area of Cala Domestica is located few kilometers from the mining district, where mainly galena and sphalerite were exploited. The area houses buildings for storage of minerals receives drainage material from mineral dumps determining a strong enrichment for several metals in the coastal sediments. Sediment core SI/69 was collected by means of vibrocorer in front of Cala Domestica beach, during a vast sampling survey aimed to environmental characterization of marine sediments. The core was subsampled in the laboratory, and a total of 28 levels were collected. Microfaunal, grain size and chemical (As, Ba, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Zn) analyses were carried out on different aliquots of the same level. The quantitative analysis on benthic foraminifera was based on the count of at least 300 specimens per sample. Faunal parameters such as Foraminiferal Number (FN i.e. number of specimens / 1 g dry sediment) and species diversity (- index and H-index) were considered as potential indicators of environmental status. Principal Component Analysis (PCA) showed a group of strongly correlated metals (Ba, Cd, Cu, Hg, Mn, Pb and Zn), associated to the superficial samples. These elements displayed a typical profile along core depth, characterized by low steady concentration in the lower part of the core, and increased values in the upper 20 cm. This pattern, which displays for most elements the highest concentrations in the top level, may be considered as influenced by anthropogenic enrichment. Quantitative faunal data were compared with concentrations by means of Canonical Correspondence Analysis (CCA) to highlight the effects of contamination on biota. It highlighted the pollution-tolerant character of some foraminiferal species, which are nearly exclusively present in the upper 20 cm core interval. Moreover, CCA demonstrated that FN was negatively affected by the anthropogenically enriched metals. Foraminiferal assemblages do not show major changes along core depth and high species diversity would suggest, in general, a good environmental status through time. Nevertheless, the comparison of assemblages from the contaminated upper core interval with reference conditions of the pre impacted interval, reveals that heavy metal pollution determined the increase of the pollution-tolerant taxa and a great decrease of foraminiferal abundance. Consequently, a comprehensive degradation of the ecological status referable to mining activity and dumping was recognized in this study.

Long-Term Changes In The Behaviour Of Jakobshavns Isbrae, West Greenland During The Late Quaternary-Holocene

NASA Astrophysics Data System (ADS)

O'Cofaigh, C.; Jennings, A.; Moros, M.; Andrews, J. T.; Kilfeather, A.; Dowdeswell, J. A.; Richter, T.

2008-12-01

This poster shows the initial results of a joint scientific project to reconstruct the Late Quaternary-Holocene behavior of Jakobshavns Isbrae in central west Greenland, one of the largest ice streams draining the modern Greenland Ice Sheet. The underlying rationale for this research is to determine if recent observed changes to the mass balance of the Greenland Ice Sheet are part of the natural variability in ice-sheet dynamics, or if they relate to anthropogenically-induced climate warming. Key to resolving this question is an understanding of long-term changes in ice sheet behavior during the Late Quaternary and the Holocene. This research will allow assessment of the links between deglaciation and internal and external environmental controls, such as the influence of inflowing Atlantic Water, and will facilitate modelling of the likely future behavior of the GIS. Currently, four marine sediment cores arrayed along a transect from the Disko Bugt Fan to Disko Bay are providing information on changes in sediment flux and sedimentation style, such as abrupt intervals of iceberg-rafting vs. "normal" hemipelagic sedimentation, as well as the paleoceanographic setting and ice sheet-ocean interactions. The cores are being analysed using a variety of proxies including IRD, mineralogy, oxygen isotopes, foraminiferal assemblages, lithofacies analysis and AMS radiocarbon dating. Data are presented from two piston cores from the continental slope at the trough-mouth fan collected during the HE0006 'shakedown' cruise to Baffin Bay and from two gravity cores recovered in 2007 during MS Merian cruise MSM 05/03 to West Greenland. Slope cores contain sequences of laminated facies interpreted as fine-grained turbidites and intervals of massive, bioturbated, hemipelagic mud. The two Merian cores, contributed to this project by the Baltic Sea Research Institute, were collected from the southern entrance to Disko Bugt and the Vaigat channel north of Disko. Radiocarbon dates from the Disko Bugt core show that it contains a full Holocene record of glacial activity and paleoceanography. The poster will present the initial analyses, including radiocarbon dating, XRF compositional data, magnetic susceptibility, lithofacies and IRD analyses determined from x-radiography, foraminiferal analyses and sediment mineralogy. Additional cores and seismic data for this project will be obtained from a cruise on the Canadian research vessel, CSS Hudson in September 2008, and on the British ship, the RRS James Clark Ross in 2009.

Patterns in bacterial and archaeal community structure and diversity in western Beaufort Sea sediments and waters

NASA Astrophysics Data System (ADS)

Hamdan, L. J.; Sikaroodi, M.; Coffin, R. B.; Gillevet, P. M.

2010-12-01

A culture-independent phylogenetic study of microbial communities in water samples and sediment cores recovered from the Beaufort Sea slope east of Point Barrow, Alaska was conducted. The goal of the work was to describe community composition in sediment and water samples and determine the influence of local environmental conditions on microbial populations. Archaeal and bacterial community composition was studied using length heterogeneity-polymerase chain reaction (LH-PCR) and multitag pyrosequencing (MTPS). Sediment samples were obtained from three piston cores on the slope (~1000m depth) arrayed along an east-west transect and one core from a depth of approximately 2000m. Discrete water samples were obtained using a CTD-rosette from three locations adjacent to piston core sites. Water sample were selected at three discrete depths within a vertically stratified (density) water column. The microbial community in near surface waters was distinct from the community observed in deeper stratified layers of the water column. Multidimensional scaling analysis (MDS) revealed that water samples from mid and deep stratified layers bore high similarity to communities in cores collected in close proximity. Overall, the highest diversity (bacteria and archaea) was observed in a core which had elevated methane concentration relative to other locations. Geochemical (e.g., bulk organic and inorganic carbon pools, nutrients, metabolites) and physical data (e.g. depth, water content) were used to reveal the abiotic factors structuring microbial communities. The analysis indicates that sediment water content (porosity) and inorganic carbon concentration are the most significant structuring elements on Beaufort shelf sedimentary microbial communities.

Chemical data for bottom sediment in Mountain Creek Lake, Dallas, Texas, 1999-2000

USGS Publications Warehouse

Wilson, Jennifer T.

2002-01-01

Mountain Creek Lake is a reservoir adjacent to the Naval Weapons Industrial Reserve Plant and the former Naval Air Station in Dallas, Texas. The U.S. Geological Survey began studies of water, sediment, and biota in the reservoir in 1994 after a Resource Conservation and Recovery Act Facility Investigation detected concentrations of organic chemicals on both facilities. Additional reservoir bottom sediment samples were collected during December 1999–January 2000 at the request of the Southern Division Naval Facilities Engineering Command to further define the occurrence and distribution of selected constituents and to supplement available data. The U.S. Geological Survey National Water Quality Laboratory analyzed bottom-sediment samples from 16 box cores and 5 gravity cores for major and trace elements, organochlorine pesticides, polychlorinated biphenyls, polycyclic aromatic hydrocarbons, grain size, and cesium-137.

The Late Pleistocene Contourites on Ceara Rise: Stratigraphy, Sedimentology and Paleoceanography

NASA Astrophysics Data System (ADS)

Ivanova, E. V.; Murdmaa, I.; Borisov, D.; Seitkalieva, E.; Ovsepyan, E.

2016-12-01

The study of sediment cores obtained during the cruises 35 (2012) and 50 (2015) of RV Akademic Ioffe from the Ceara Rise in the western tropical Atlantic strongly supports a significant influence of bottom (contour) currents on the Late Quaternary sedimentation. Seismic evidence of contourites in the study area (migrating contourite sediment waves, furrows) was previously described by Kumar and Embley (1977) and Curry et al. (1995). Widespread distribution of seismic waves on the rise and adjacent areas was suggested by Murdmaa et al (2014) based on the results of high-resolution seismic profiling with SES-2000 deep (4-5 kHz) in 2012. Our sediment cores recovered intercalation of bioturbated clays and silty clays with thin linear or wavy sand and silt layers and lenses implying strong bottom current control on sedimentation. The stratigraphic frame of the reference core AI-3426 retrieved near the summit of the Ceara Rise, at the water depth of 3046 m is based on the foraminiferal (Globorotalia menardii zones), oxygen isotope and AMS-14C data. The core recovered sediments of the last 140 ka with very rich and well-preserved tropical planktic foraminiferal assemblages. G. menardii is common within MIS 1 and 5 and is almost absent in MIS 2-4 and upper MIS 6. The abundance of benthic foraminifers is rather low. However, dominance of Globocassidulina subglobosa in benthic assemblages likely indicates a moderate bottom-current activity on the Ceara Rise during the last glacial. The other 4-5m long sediment cores collected along the seismic profile from the northern and southern slopes demonstrate the similar contourite sedimentological features and insignificant reworking of the Neogene foraminiferal species as inferred from the core AI-3426 along with the significant variations in foraminiferal preservation during the Pleistocene. The study is supported by the projects RSF 14-50-00095, RFBR 14-05-00744 and RFBR 16-35-60111, and Program I3P by RAS.

Sedimentation of oil-derived material to the seabed is an unrecognized fate for oil derived from natural seepage.

NASA Astrophysics Data System (ADS)

Joye, S. B.

2016-02-01

The fate of oil derived from natural seepage in the marine environment is poorly constrained. In the aftermath of the 2010 BP/Macondo oil well blowout, sedimentation of oil-containing material to the seafloor was an important fate for discharged oil. Though the amount of oil accounted for by sedimentation processes remains poorly constrained, sedimentation is now considered an important fate of oil during large open water spills that generate extensive surface slicks. In the Gulf of Mexico, vigorous natural oil seeps generate extensive, sometimes thick, surface slicks. In the case of highly active seeps, these surface oil slicks persist at the sea surface over the seep site a majority of the time. We investigated the fate of oil released through natural seepage and the potential for the sedimentation of surface-slick derived oil at two vigorous hydrocarbon seeps in the Gulf of Mexico, Green Canyon block 600 and block 767. Hydrocarbon analyses were performed on samples collected from oil vents at the seafloor, in surface slicks, and in sediments cores apparently containing sedimented oil. Sediment cores collected from both of these active seep sites away from known oil vents contained distinct (1-3 cm thick) layers that were brown in coloration and which displayed distinct sedimentology compared to deeper strata. The oil fingerprint was also different, suggesting this material was not the result of weathering during transit through the sediment column. Available data suggest that sedimentation of weathered oil also occurs at vigorous natural seeps. Detailed studies of the weathered oil sedimentation process at natural seeps will help reveal the mechanisms driving this phenomena and are important for understanding the fate of oil released during accidental discharges and spills.

Developing Age Models to Utilize High Arctic Coastal Sediments for Paleoclimate Research: Results from the Colville Delta and Simpson Lagoon, Alaska

NASA Astrophysics Data System (ADS)

Miller, A. J.; Allison, M. A.; Bianchi, T. S.; Marcantonio, F.

2012-12-01

Sediment cores collected from Simpson Lagoon on the inner Beaufort Sea shelf adjacent to the Colville River delta, AK are being utilized to develop new, high-resolution (sub-decadal scale) archives of the 0-3,000 year Arctic paleoclimate record necessary to assess natural and anthropogenic climate variability. An imperative first step for developing a new paleoclimate archive is to establish methodologies for constraining the age-depth relationship. Naturally occurring and bomb-produced radioisotopes have been utilized in sediments to constrain downcore variability of accumulation rates on 100-103 y timescales, but this methodology is complicated by low activities of many of these tracers at high latitudes. The present study utilizes the combination of a (1) multi-tracer approach and a (2) tailored measurement strategy to overcome this limitation. 210Pb and 137Cs analyses were conducted on the fine (<32μm) sediment fraction to maximize measurable activity and to minimize radioisotope activity variability resulting from changes in grain size: 137Cs geochronologies proved more reliable in this setting and revealed mm/y sediment accumulation in the lagoon. To corroborate the 137Cs results, 239,240Pu activities were analyzed for selected sites using ICP-MS which has ultra-low detection limits, and yielded accumulation rates that matched the Cs geochronology. Age model development for the remainder of the core lengths (>~100 y in age) were completed using radiocarbon dating of benthic foraminifera tests, which proved the only datable in situ carbon available in this sediment archive. These dates have been used to constrain the ages of acoustic reflectors in CHIRP subbottom seismic records collected from the lagoon. Using this age control, spatial patterns of lagoonal sediment accumulation over the last ~3 ky were derived from the CHIRP data. Two depocenters are identified and validate combining age-dated coring with high-resolution seismic profiling to identify areas of the highest temporal resolution for Arctic paleoclimate research in coastal sediments.

Fingerprinting the main erosion processes delivering sediment to hillside reservoirs: Case of Kamech catchment in Cape Bon, Tunisia

NASA Astrophysics Data System (ADS)

Ben Slimane, A.; Raclot, D.; Evrard, O.; Sanaa, M.; Lefèvre, I.; Ahmadi, M.; Le Bissonnais, Y.

2011-12-01

About 74% of agricultural soils are affected by water erosion in Tunisia. This intense soil degradation threatens the sustainability of food production in the country. It also leads to the siltation of the numerous hillslide reservoirs that were constructed in the 1990s to protect downstream villages against floods and provide a source of water in cultivated areas. Very dense gully systems are observed in Tunisian agricultural land and in other Mediterranean regions, but their contribution to contemporary sediment supply to hillside reservoirs has not been quantified yet. Still, there is a need to quantify the sediment sources in this region in order to guide the implementation of erosion control measures. Sediment can be supplied by gully systems but it can also be provided by erosion of the superficial layer of cultivated soil. We propose a methodology to estimate the relative contribution of gully erosion vs. interrill erosion to the sediment accumulated in hillside reservoirs. This work was conducted in a pilot catchment (i.e., Kamech catchment, 263ha, Cape Bon, Tunisia) to define guidelines on the number and the location of sediment core samples to collect in the reservoirs, in order to provide relevant information on the evolution of sediment sources throughout the last two decades. Once validated, this methodology will be applied to other catchments of the Tunisian Ridge. We applied the sediment fingerprinting method, which consists in measuring conservative and stable properties in both sources and sinks of sediment to outline their origin. Sampling efforts were concentrated on the field surface (cropland and grassland), gullies and channel banks. Thirteen sediment cores were collected along an upstream-downstream transect across Kamech hillside reservoir, in order to estimate the contribution of each potential sediment source to the material accumulated at the outlet, and to investigate the potential spatial differences of sediment origin across the reservoir. Concentration in two types of tracers (i.e., radionuclides and organic matter) was analyzed in all samples to provide potential fingerprinting properties, and a Monte Carlo mixing model was applied. Among the 11 potential tracers, 137Cs, total nitrogen and total organic carbon were selected. Application of the mixing model outlined that a mean homogenized sample provided similar information on the sediment origin as the analysis of all successive sediment layers observed in the core. We subsequently focused on the interpretation of the results obtained for those "mean" homogenised core samples. Those results showed that the dominant sources varied along the reservoir transect. However, the overall dominant source of sediment was interrill erosion. Soil conservation measures need therefore to be applied on cultivated land of Kamech catchment to limit siltation.

Radionuclide activities and metal concentrations in sediments of the Sebou Estuary, NW Morocco, following a flooding event.

PubMed

Laissaoui, A; Mas, J L; Hurtado, S; Ziad, N; Villa, M; Benmansour, M

2013-06-01

This study presents metal concentrations (Fe, Mg, Mn, Co, Cu, Zn, Pb, As, Sr and V) and radionuclide activities ((40)K, (137)Cs, (210)Pb, (226)Ra, (228)Ac, (234)Th and (212)Pb) in surface deposits and a sediment core from the Sebou Estuary, Northwest Morocco. Samples were collected in April 2009, about 2 months after a flooding event, and analysed using a well-type coaxial gamma-ray detector and inductively coupled plasma-quadrupole mass spectrometry. Activities of radionuclides and concentrations of almost all elements in surface samples displayed only moderate spatial variation, suggesting homogenous deposition of eroded local soil in response to intense precipitation. Excess (210)Pb displayed relatively constant activity throughout the sediment core, preventing dating and precluding determination of the historical accumulation rates of pollutants at the core site. Some elements showed non-systematic trends with depth and displayed local maxima and minima. Other elements presented relatively systematic concentration trends or relatively constant levels with discrete maxima and/or minima. Except for Mn, Sr and Cr, all metal concentrations in sediment were below levels typical of polluted systems, suggesting little human impact or losses of metals from sediment particles.

Enhanced Sulfate Reduction and Carbon Sequestration in Sediments Underlying the Core of the Arabian Sea Oxygen Minimum Zone

NASA Astrophysics Data System (ADS)

Fernandes, S. Q.; Mazumdar, A.; Peketi, A.; Bhattacharya, S.; Carvalho, M.; Da Silva, R.; Roy, R.; Mapder, T.; Roy, C.; Banik, S. K.; Ghosh, W.

2017-12-01

The oxygen minimum zone (OMZ) of the Arabian Sea in the northern Indian Ocean is one of the three major global sites of open ocean denitrification. The functionally anoxic water column between 150 to 1200 mbsl plays host to unique biogeochemical processes and organism interactions. Little is known, however, about the consequence of the low dissolved oxygen on the underlying sedimentary biogeochemical processes. Here we present, for the first time, a comprehensive investigation of sediment biogeochemistry of the Arabian Sea OMZ by coupling pore fluid analyses with microbial diversity data in eight sediment cores collected across a transect off the west coast of India in the Eastern Arabian Sea. We observed that in sediments underlying the core of the OMZ, high organic carbon sequestration coincides with a high diversity of all bacteria (the majority of which are complex organic matter hydrolyzers) and sulfate reducing bacteria (simple organic compound utilizers). Depth-integrated sulfate reduction rate also intensifies in this territory. These biogeochemical features, together with the detected shallowing of the sulfate-methane interface and buildup of pore-water sulfide, are all reflective of heightened carbon-sulfur cycling in the sediments underlying the OMZ core. Our data suggests that the sediment biogeochemistry of the OMZ is sensitive to minute changes in bottom water dissolved oxygen, and is dictated by the potential abundance and bioavailability of complex to simple carbon compounds which can stimulate a cascade of geomicrobial activities pertaining to the carbon-sulfur cycle. Our findings hold implications in benthic ecology and sediment diagenesis.

Trace element distribution in the water and sediments of certain storage lakes from the Jijia catchment, (Romania)

NASA Astrophysics Data System (ADS)

Dughila, A.; Iancu, O. G.; Romanescu, G. T.

2012-04-01

The present study aims at investigating the concentrations and distribution levels of a series of trace elements in water and sediment samples collected from six storage lakes located in the Jijia catchment - NE of Romania. The lakes are multi-purpose water reservoirs, three of them being mainly used as a source of municipal drinking water, or for fishing, irrigation for the farms in the area, protection against floods and the regulation of river flows. By contrast, agricultural wastes, fertilizers, raw sewage effluents and road runoff constitute the predominant anthropogenic sources, which supply the lakes in question with Cd, Cu, Pb and Zn. The present study was conducted on a series of 63 sediment samples and 18 water samples, collected from the same locations, in order to establish the distribution levels of certain trace elements from the water through sediments. Sediment cores were collected from two sections across each lake by means of a motor boat, using a system that consists of a graduated sampling tube (0.9 m in length and 72.5 mm in diameter) made of Plexiglas (Eijkelkamp sample tube guide). Prior to the analyses, the samples were air-dried, ground and homogenized using an agate mortar, oven-dried at 50 °C for 6 days and then sieved through 63 µm sieves. The sediment and water samples were subjected to a digestion technique with concentrated nitric acid using a microwave oven (Berghof type), and analyzed for the following elements: Pb, Zn, Cu, Cd, Cr and Ni. The total concentration of the elements was measured through atomic absorption spectrometry (AAS) with an RSD of < 10 % from solutions. The vertical distribution of most elements in the cores examined could be characterized as relatively uniform, with higher concentrations for those collected from the lakes which are more influenced by anthropogenic factors, compared to those situated in forested areas. The lake-water quality characteristics were below the recommended drinking water standards imposed by the current legislation (MMGA Ord. No. 161/16.02.2006 - Normative regarding the classification of surface waters in order to establish the ecological status of water bodies, which combines European and Romanian provisions), with the exception of copper (with very high concentrations in all the water samples), lead and cadmium. Keywords: AAS, Jijia catchment (Romania), lake water, sediment core, trace elements

Continuous and Episodic Modern Sediment Accumulation on Monterey Fan: Evidence from Ddt, 137Cs and Excess 210Pb

NASA Astrophysics Data System (ADS)

Gwiazda, R.; Paull, C. K.; Alexander, C. R.; Ussler, W.

2012-12-01

The mode and magnitude of fine-grained sediment accumulation on the Monterey Fan off the California central coast was investigated using pesticide concentrations and radioactive tracer profiles in sediment cores. DDT is a man-made pesticide that was used extensively in central California between 1945 and 1970. As such, its presence in marine sediments is a telltale sign of a modern sedimentation age. DDT and its metabolites, DDE and DDD, (collectively referred to as DDTr) were measured in fifty-five ~20cm-long sediment cores collected from the surface of the Monterey Fan up to 250 km to the south and 210 km to the west of the Monterey Canyon head, and in four transects across the Monterey Canyon channel at maximum water depths of 3160, 3380, 3580, and 3880 meters. Profiles of excess 210Pb (210Pbxs) and 137Cs were measured in 5 cores from the Fan to estimate recent sedimentation rates. Detectable levels of DDTr were observed in all but one of these cores, with DDTr concentrations characteristically highest at the surface and decreasing with depth. The area-normalized and depth-integrated DDTr content measured in all the cores in the Fan and in the deepest two channel transects was geographically fairly homogenous, with no statistical relationship between DDTr inventory and distance from the main channel crossing the Fan. The total sediment mass deposited on the Fan over the last 60 years, inferred from the total inventory of DDTr present in the area surveyed, is consistent with the amount of sediment delivered by the Salinas River over the same time period. 210Pbxs activities are fairly homogeneous within an uppermost layer of variable thickness (4.6-8cm) and decrease exponentially below it, but these exponential decreases are often interrupted by horizons with constant or increased 210Pbxs activity. Moreover, the coexistence of variable DDTr concentrations with homogeneous 210Pbxs activities in the top sediment indicates that the uniformity of 210Pbxs is not due primarily to bioturbation but rather the result of deposition of thick layers with constant 210Pbxs. These data indicate that fine-grained sedimentation on the Monterrey Fan appears to have a dual modality consisting of sustained slow accumulation at a modest rate during quiescent periods interrupted by episodes of rapid accumulation during discrete events. Median sedimentation rates during quiescent periods are 0.07 cm yr-1, but over the 110 year period of detectable 210Pbxs, which includes both slow continuous sedimentation and rapid accumulation events, the median overall sedimentation rate, calculated from the deepest detectable 210Pbxs samples, is 0.19 cm yr-1. On a per mass basis, sedimentation on the Fan has been equally divided between periods of continual slow accumulation and episodes of fast accumulation. The rapidly deposited layers on the Monterey Fan are inferred to result from the injection of fluvial sediments onto the Fan during episodic and exceptionally large floods of the Salinas River.

Using recent hurricanes and associated event layers to evaluate regional storm impacts on estuarine-wetland systems

NASA Astrophysics Data System (ADS)

Smith, C. G.; Marot, M. E.; Osterman, L. E.; Adams, C. S.; Haller, C.; Jones, M.

2016-12-01

Tropical cyclones are a major driver of change in coastal and estuarine environments. Heightened waves and sea level associated with tropical cyclones act to erode sediment from one environment and redistribute it to adjacent environments. The fate and transport of this redistributed material is of great importance to the long-term sediment budget, which in turns affects the vulnerability of these coastal systems. The spatial variance in both storm impacts and sediment redistribution is large. At the regional-scale, difference in storm impacts can often be attributed to natural variability in geologic parameters (sediment availability/erodibility), coastal geomorphology (including fetch, shoreline tortuosity, back-barrier versus estuarine shoreline, etc.), storm characteristics (intensity, duration, track/approach), and ecology (vegetation type, gradient, density). To assess storm characteristics and coastal geomorphology on a regional-scale, cores were collected from seven Juncus marshes located in coastal regions of Alabama and Mississippi (i.e., Mobile Bay, Bon Secour Bay, Mississippi Sound, and Grand Bay) expected to have been impacted by Hurricane Frederic (1979). All cores were sectioned and processed for water content, organic matter (loss-on-ignition), and select cores analyzed for foraminiferal assemblages, stable isotopes and bulk metals to aid in the identification of storm events. Excess lead-210 and cesium-137 were used to develop chronologies for the cores and evaluate mass accumulation rates and sedimentation rates. Temporal variations in accumulation rates of inorganic and organic sediments were compared with shoreline and areal change rates derived from historic aerial imagery to evaluate potential changes in sediment exchange prior to, during, and following the storm. A combined geospatial and geologic approach will improve our understanding of coastal change in estuarine marsh environments, as well help refine the influence of storms on regional sediment budgets.

Subsurface sediment contamination during borehole drilling with an air-actuated down-hole hammer.

PubMed

Malard, Florian; Datry, Thibault; Gibert, Janine

2005-10-01

Drilling methods can severely alter physical, chemical, and biological properties of aquifers, thereby influencing the reliability of water samples collected from groundwater monitoring wells. Because of their fast drilling rate, air-actuated hammers are increasingly used for the installation of groundwater monitoring wells in unconsolidated sediments. However, oil entrained in the air stream to lubricate the hammer-actuating device can contaminate subsurface sediments. Concentrations of total hydrocarbons, heavy metals (Cu, Ni, Cr, Zn, Pb, and Cd), and nutrients (particulate organic carbon, nitrogen, and phosphorus) were measured in continuous sediment cores recovered during the completion of a 26-m deep borehole drilled with a down-hole hammer in glaciofluvial deposits. Total hydrocarbons, Cu, Ni, Cr and particulate organic carbon (POC) were all measured at concentrations far exceeding background levels in most sediment cores. Hydrocarbon concentration averaged 124 +/- 118 mg kg(-1) dry sediment (n = 78 samples) with peaks at depths of 8, 14, and 20 m below the soil surface (maximum concentration: 606 mg kg(-1)). The concentrations of hydrocarbons, Cu, Ni, Cr, and POC were positively correlated and exhibited a highly irregular vertical pattern, that probably reflected variations in air loss within glaciofluvial deposits during drilling. Because the penetration of contaminated air into the formation is unpreventable, the representativeness of groundwater samples collected may be questioned. It is concluded that air percussion drilling has strong limitations for well installation in groundwater quality monitoring surveys.

Holocene Paleolimnological Records from Thule, Northwestern Greenland

NASA Astrophysics Data System (ADS)

Corbett, L.; Osterberg, E. C.; Kelly, M. A.; Axford, Y.

2012-12-01

Assessing Holocene climatic and environmental variability around the margin of the Greenland Ice Sheet provides important information against which to compare ice sheet margin fluctuations. Here, we report preliminary results from ongoing research in northwestern Greenland. We present records of physical properties of lake sediments and use these to make inferences about the evolution of the lake and its surroundings over the latter half of the Holocene. We collected two sediment cores, 90 and 72 cm in length, from a small (surface area ~0.3 km2), shallow (maximum depth ~4.5 m) lake at 76°33'40''N 68°26'31''W near Thule Air Base in July 2012. The length of the cores was limited by the length of the core barrel and does not reflect the total thickness of sediment in the lake. The lake is situated within the glacial limit and likely formed subsequent to deglaciation of the region during early Holocene time. No glaciers exist within the lake's catchment today; the primary modern source of sediment is a perennial inflow from the west. We developed a preliminary depth-age model using radiocarbon ages of terrestrial organic macrofossils. Thus far, we have analyzed the sediments for magnetic susceptibility and loss-on-ignition. A radiocarbon age of 6069 ± 90 cal yr BP at the base of the core indicates that the sediments preserve a continuous record of middle to late Holocene conditions. The top of both cores consists of a thick (~12 cm) layer of dark gray unlaminated sediments, while the rest of the material in both cores is lighter brown to olive, finely laminated sediment. The upper layer is characterized by low water content (<25%), low loss-on-ignition (<5%), and high magnetic susceptibility (~150-250 x10-6). Conversely, the laminated sediments beneath have higher water content (~40-50%), higher loss-on-ignition (~5-10%), and much lower magnetic susceptibility (<50 x10-6). We hypothesize that the upper, less organic unit may represent a single event in the lake's recent history. We are refining the depth-age model with more radiocarbon ages, measuring grain size and carbon to nitrogen ratios of the sediments, and evaluating possible linkages between the sediment physical properties and precipitation as recorded by annual accumulation in ice cores in northwestern Greenland and Arctic Canada. This project will provide a foundation for future work in Thule investigating Holocene fluctuations of local ice cap and ice sheet margin positions.

Innovations in Sampling Pore Fluids From Deep-Sea Hydrate Sites

NASA Astrophysics Data System (ADS)

Lapham, L. L.; Chanton, J. P.; Martens, C. S.; Schaefer, H.; Chapman, N. R.; Pohlman, J. W.

2003-12-01

We have developed a sea-floor probe capable of collecting and returning undecompressed pore water samples at in situ pressures for determination of dissolved gas concentrations and isotopic values in deep-sea sediments. In the summer of 2003, we tested this instrument in sediments containing gas hydrates off Vancouver Island, Cascadia Margin from ROPOS (a remotely operated vehicle) and in the Gulf of Mexico from Johnson-Sea-Link I (a manned submersible). Sediment push cores were collected alongside the probe to compare methane concentrations and stable carbon isotope compositions in decompressed samples vs. in situ samples obtained by probe. When sufficient gas was available, ethane and propane concentrations and isotopes were also compared. Preliminary data show maximum concentrations of dissolved methane to be 5mM at the Cascadia Margin Fish Boat site (850m water depth) and 12mM in the Gulf of Mexico Bush Hill hydrate site (550m water depth). Methane concentrations were, on average, five times as high in probe samples as in the cores. Carbon isotopic values show a thermogenic input and oxidative effects approaching the sediment-water interface at both sites. This novel data set will provide information that is critical to the understanding of the in situ processes and environmental conditions controlling gas hydrate occurrences in sediments.

Heavy metal concentrations and the variations of foraminifers in the Silivri-Kumbagi area (NW Marmara Sea, Turkey)

NASA Astrophysics Data System (ADS)

Ünal Yümün, Zeki; Murat Kılıç, Ali; Önce, Melike

2016-04-01

In the area between Silivri (İstanbul) and Kumbagi (Tekirdag), NW of Marmara Sea, there is a considerable extent in marine pollution from industrial and settlements wastes, sea transports, and agricultural activities. The most important one of these pollutions is the spread of heavy metals. Our research investigated sediments in order to determine whether heavy minerals affected biota such as recent foraminifers, or not. Our investigation area starts from Marmara Ereglisi, in the east, continues to Tekirdag and Kumbagi, in the west. 10 sea-water samples, 10 sediment-core samples and one 10 m core-drilling sample, taken 250 m off-shore from coast line. As a result of this sampling geochemical analysis of the bottom-mud and water samples were done and the ratio of heavy metals and other contaminants determined. For heavy metal analyses, concentration analysis of 12 heavy metals (Cd, Fe, Cu, Pb, Zn, Al, Co, Cr, Mn, Ni, As, and Hg) has been conducted, as ppm, in sediment samples taken from the levels in which foraminifers are collected. Perpendicular (spatial) heavy metal concentration changes have been determined with off-shore drilling samples and horizontal changes (geochronological) have been determined with the help of core samples. Especially, it has been understood that heavy metal concentrations in recent sediments are higher compared to the past. In this research the samples have been taken from each 10 cm. of core and drilling samples to collect the benthic foraminifers. In this context, 15 grams of dry sediment sample taken from each level, have been washed in 125 μm sieves in order to determine its benthic foraminifer content. Benthic foraminifera from these samples have been identified taxonomically and their morphological differentiation has been determined after taking SEM photos. As a result of this study, the foraminifera types of "Adelosinacliarensis, Adelosinamediteranensis, Adelosinapulchella, Ammonia compacta, Ammonia parkinsonia, Ammonia tepida, Cribroelphidiumpoeyonum, Cycloforinacontorta, Elphidiumaculeatum, Elphidiumcomplanatum, Elphidiumcrispum, Elphidiumgalvestonense, Lobatulalobatula, Massilinasecans, Miliolinellasubrotunda, Pseudotriloculinaoblanga, Quinqueloculina seminula, Quinqueloculina polygona, Spiroloculinaangulosa, Spiroloculinaexcavata, Triloculina marioni" have been determined. Especially in the Elphidiumcrispumand Ammonia compacta, collected from the core samples taken from Marmara Ereglisi (Tekirdag) and Silivri (Istanbul) offshore, some morphological variations, colour changes, abnormality and multiple-individuals, were observed. Increasing of the heavy metal concentration in the levels of these morphological variations is noticeable.

Estimated sediment thickness, quality, and toxicity to benthic organisms in selected impoundments in Massachusetts

USGS Publications Warehouse

Breault, Robert F.; Sorenson, Jason R.; Weiskel, Peter K.

2013-01-01

The U.S. Geological Survey and the Massachusetts Department of Fish and Game, Division of Ecological Restoration, collaborated to collect baseline information on the quantity and quality of sediment impounded behind selected dams in Massachusetts, including sediment thickness and the occurrence of contaminants potentially toxic to benthic organisms. The thicknesses of impounded sediments were measured, and cores of sediment were collected from 32 impoundments in 2004 and 2005. Cores were chemically analyzed, and concentrations of 32 inorganic elements and 108 organic compounds were quantified. Sediment thicknesses varied considerably among the 32 impoundments, with an average thickness of 3.7 feet. Estimated volumes also varied greatly, ranging from 100,000 cubic feet to 81 million cubic feet. Concentrations of toxic contaminants as well as the number of contaminants detected above analytical quantification levels (also known as laboratory reporting levels) varied greatly among sampling locations. Based on measured contaminant concentrations and comparison to published screening thresholds, bottom sediments were predicted to be toxic to bottom-dwelling (benthic) organisms in slightly under 30 percent of the impoundments sampled. Statistically significant relations were found between several of the contaminants and individual indicators of urban land use and industrial activity in the upstream drainage areas of the impoundments. However, models developed to estimate contaminant concentrations at unsampled sites from upstream landscape characteristics had low predictive power, consistent with the long and complex land-use history that is typical of many drainage areas in Massachusetts.

Historical deposition of mercury and selected trace elements to high-elevation National Parks in the Western U.S. inferred from lake-sediment cores

USGS Publications Warehouse

Mast, M. Alisa; Manthorne, David J.; Roth, David A.

2010-01-01

Atmospheric deposition of Hg and selected trace elements was reconstructed over the past 150 years using sediment cores collected from nine remote, high-elevation lakes in Rocky Mountain National Park in Colorado and Glacier National Park in Montana. Cores were age dated by 210Pb, and sedimentation rates were determined using the constant rate of supply model. Hg concentrations in most of the cores began to increase around 1900, reaching a peak sometime after 1980. Other trace elements, particularly Pb and Cd, showed similar post-industrial increases in lake sediments, confirming that anthropogenic contaminants are reaching remote areas of the Rocky Mountains via atmospheric transport and deposition. Preindustrial (pre-1875) Hg fluxes in the sediment ranged from 5.7 to 42 μg m−2 yr−1 and modern (post-1985) fluxes ranged from 17.7 to 141 μg m−2 yr−1. The average ratio of modern to preindustrial fluxes was 3.2, which is similar to remote lakes elsewhere in North America. Estimates of net atmospheric deposition based on the cores were 3.1 μg m−2 yr−1 for preindustrial and 11.7 μg m−2 yr−1for modern times. Current-day measurements of wet deposition range from 5.0 to 8.6 μg m−2 yr−1, which are lower than the modern sediment-based estimate of 11.7 μg m−2 yr−1, perhaps owing to inputs of dry-deposited Hg to the lakes.

An historical assessment of trace metal accumulation in Lake Champlain, Vermont

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mecray, E.L.; King, J.W.

1993-03-01

The Lake Champlain watershed, with its increased land use, shoreline development, and population, is being threatened by pollutants in the water column and bottom sediments. A comprehensive study is currently being conducted to characterize the bottom sediments of the lake for toxicity and to reconstruct the history of pollutant inputs. Surface sediment samples were collected from 30 stations and analyzed for metal (Cu, Zn, Cr, Pb, Ni, Mn, Fe, Cd, Al, and Ag) concentrations to determine the contaminated regions of the lake. Once the contaminated regions were determined, a Nemesis corer was used to retrieve sediments cores averaging 1 metermore » in length from 10 sites within Lake Champlain. Grain size and metal analyses were conducted at one and two cm intervals down the cores. Grain size data, in combination with metal and radiometric stratigraphy, can serve as an indicator of changing land use in the watershed. The grain size in some cores has a fining upward trend indicating increased land use and soil erosion. Downcore variations in metal concentrations reveal two different regimes. The concentration at depth remain consistently low and are inferred to correspond with the natural background levels. In contrast, the upper section of the cores show abrupt increases in metal concentrations which are attributed to increased anthropogenic inputs. Radiometric ([sup 210] and [sup 137]Cs) and pollen chronostratigraphy of these cores indicates that the increased metal concentrations and the changes in grain size recorded in the upper most sediments is related to increased human disturbance beginning in the late 18th and early 19th centuries. This study demonstrates that the historical record of pollution inputs to Lake Champlain can be reconstructed from the sediment sequences.« less

Non-destructive X-ray Computed Tomography (XCT) Analysis of Sediment Variance in Marine Cores

NASA Astrophysics Data System (ADS)

Oti, E.; Polyak, L. V.; Dipre, G.; Sawyer, D.; Cook, A.

2015-12-01

Benthic activity within marine sediments can alter the physical properties of the sediment as well as indicate nutrient flux and ocean temperatures. We examine burrowing features in sediment cores from the western Arctic Ocean collected during the 2005 Healy-Oden TransArctic Expedition (HOTRAX) and from the Gulf of Mexico Integrated Ocean Drilling Program (IODP) Expedition 308. While traditional methods for studying bioturbation require physical dissection of the cores, we assess burrowing using an X-ray computed tomography (XCT) scanner. XCT noninvasively images the sediment cores in three dimensions and produces density sensitive images suitable for quantitative analysis. XCT units are recorded as Hounsfield Units (HU), where -999 is air, 0 is water, and 4000-5000 would be a higher density mineral, such as pyrite. We rely on the fundamental assumption that sediments are deposited horizontally, and we analyze the variance over each flat-lying slice. The variance describes the spread of pixel values over a slice. When sediments are reworked, drawing higher and lower density matrix into a layer, the variance increases. Examples of this can be seen in two slices in core 19H-3A from Site U1324 of IODP Expedition 308. The first slice, located 165.6 meters below sea floor consists of relatively undisturbed sediment. Because of this, the majority of the sediment values fall between 1406 and 1497 HU, thus giving the slice a comparatively small variance of 819.7. The second slice, located 166.1 meters below sea floor, features a lower density sediment matrix disturbed by burrow tubes and the inclusion of a high density mineral. As a result, the Hounsfield Units have a larger variance of 1,197.5, which is a result of sediment matrix values that range from 1220 to 1260 HU, the high-density mineral value of 1920 HU and the burrow tubes that range from 1300 to 1410 HU. Analyzing this variance allows us to observe changes in the sediment matrix and more specifically capture where, and to what extent, the burrow tubes deviate from the sediment matrix. Future research will correlate changes in variance due to bioturbation to other features indicating ocean temperatures and nutrient flux, such as foraminifera counts and oxygen isotope data.

Sedimentological, mineralogical, and geochemical results from surface sediments and the sediment record from Site 2 of the ICDP drilling project at Lake Towuti, Indonesia

NASA Astrophysics Data System (ADS)

Hasberg, A. K.; Melles, M.; Wennrich, V.; Vogel, H.; Just, J.; Russell, J. M.; Bijaksana, S.; Morlock, M.; Opitz, S.

2017-12-01

More than 1000 m of sediment core were recovered in spring 2015 from three different drill sites in tropical Lake Towuti (2.5°S, 121°E), Indonesia, during the Towuti Drilling Project (TDP) of the International Continental Scientific Drilling Program (ICDP). Furthermore, a set of 84 lake surface sediment samples, distributed over the entire lake, was collected in order to better understand modern sedimentary processes. The surface samples were investigated for physical, chemical, mineralogical, and biological properties at the University of Cologne (UoC), Germany. On the sediment cores macro- and microscopical lithological descriptions, line-scan imaging, logging of physical properties (MSCL), and subsampling was conducted at the National Lacustrine Core Facility of the University of Minnesota, USA, in November 2015 and January 2016. Afterwards, the archive core halves and 672 subsamples of TDP Site 2 were shipped to the UoC for X-Ray Fluorescence (XRF) scanning and sedimentological, geochemical, and mineralogical analyses, respectively, supplemented by visible to near-infrared spectroscopy (VNIR) at Brown University, USA. The data from the surface samples evidence that allochthonous sedimentation in Lake Towuti today is dominated by fluvial supply from five distinguishable source areas: (i) the Mahalona River to the north, which drains lakes Mahalona and Matano, (ii) inlets around the village of Timampu to the northwest, (iii) the Loeha River to the east, (iv) the Lengke River to the south, and (v) the Lemo-Lemo River to the northeast of Lake Towuti. Of these, source areas (ii) and (iii) as well as (iv) and (v) have similar geochemical compositions, respectively. In addition, the lake sedimentation is significantly influenced by gravitational sediment supply from steep slopes as well as lake-internal gravitational and density-driven processes. The uppermost 41 m of sediment core 2A consist of pelagic sediments (totaling 11 m) and event layers from mass movement ( 30 m) that were formed during the past 50 cal kyr. In this period, the data reflect significant climatic and environmental changes, in particular in precipitation and lake level. These changes seem to be coupled to prominent paleoclimatic events.

Sediment records of Yellow River channel migration and Holocene environmental evolution of the Hetao Plain, northern China

NASA Astrophysics Data System (ADS)

Wang, Jingzhong; Wu, Jinglu; Pan, Baotian; Jia, Hongjuan; Li, Xiao; Wei, Hao

2018-05-01

The origin and evolution of lakes in the Hetao Plain, northern China, were influenced by climate variation, channel migration, and human activity. We analyzed a suite of sediment cores from the region to investigate Yellow River channel migration and environmental change in this region over the Holocene. Short sediment cores show that environmental indicators changed markedly around CE 1850, a time that corresponds to flood events, when large amounts of river water accumulated in the western part of the Hetao Plain, giving rise to abundant small lakes. Multiple sediment variables (environmental proxies) from two long cores collected in the Tushenze Paleolake area show that sediments deposited between 12.0 and 9.0 cal ka BP were yellow clay, indicative of fluvial deposition and channel migration. From 9.0 to 7.5 cal ka BP, sand was deposited, reflecting a desert environment. From 7.5 to 2.2 cal ka BP, however, the sediments were blue-gray clay that represents lacustrine facies of Lake Tushenze, which owes its origin to an increase in strength of the East Asian monsoon. At about 2.2 cal ka BP, the north branch of the Yellow River was flooded, and the Tushenze Paleolake developed further. Around 2.0 cal ka BP, the paleolake shrank and eolian sedimentation was recorded. The analyzed sediment records are consistent with the written history from the region, which documents channel migration and environmental changes in the Hetao Plain over the Holocene.

Strontium Isotope Dating of Metalliferous Sediment in the SW Pacific Basin

NASA Astrophysics Data System (ADS)

Stancin, A. M.; Gleason, J. D.; Owen, B. M.; Rea, D. K.; Moore, T. C.; Hendy, I. L.; Lyle, M. W.; Blum, J. D.

2007-12-01

A 2 million km2 region virtually devoid of sediment was identified in the remote SW Pacific Basin during the TUIM- 3 2005 drill site survey cruise. This region, termed the "South Pacific Bare Zone", comprises ocean floor dating back to the Late Cretaceous. Within the Bare Zone, a small (1km2) abyssal valley containing sediment to a depth of 24 m was sampled using a large diameter piston core (MV0502-15JC, 31 ° 42.194'S, 143 ° 30.331'W), leading to recovery of 8.35 m of metalliferous sediment at 5082 m water depth. Fish-teeth Sr-isotope stratigraphy reveals a continuous record of sedimentation from 31 Ma to present at this site. The fish teeth age-depth profile and INAA geochemistry reveal an exponentially decreasing hydrothermal flux, with sedimentation rates approaching 0.05 mm/kyr after 20 Ma. The source of hydrothermal activity at this site was likely the Pacific- Farallon Ridge, which went extinct at 20 Ma. A second piston core (MV0502-16JC; 28 ° 05.151'S, 140 ° 14.140'W) was collected near MacDonald Seamounts located on the southeastern end of the Cook-Austral island chain outside the Bare Zone and recovered 10.5 m of hydrothermal sediment and biogenic ooze. The lower 65 cm of the core consists of a coccolith ooze. From 10 mbsf depth to 1.5 mbsf depth, the core contians reddish black zeolitic clay, while the upper 1.5 mbsf contains biogenic ooze associated with abundant Late Pleistocene foraminifera remains. Concordant nannofossil and fish teeth ages at the base of the core (27-28 Ma), and Pleistocene ages near the top of the core reinforce the validity of the Sr fish teeth method for dating hydrothermal cores. These independent records suggest that regional hydrothermal activity during the Oligocene may have been related to a series of late Eocene/early Oligocene ridge jumps, propagating rifts and seafloor spreading centers that accompanied large-scale plate tectonic reorganization of South Pacific seafloor.

Ecosystem history of South Florida; Biscayne Bay sediment core descriptions

USGS Publications Warehouse

Ishman, S.E.

1997-01-01

The 'Ecosystem History of Biscayne Bay and the southeast Coast' project of the U.S. Geological Survey is part of a multi-disciplinary effort that includes Florida Bay and the Everglades to provide paleoecologic reconstructions for the south Florida region. Reconstructions of past salinity, nutrients, substrate, and water quality are needed to determine ecosystem variability due to both natural and human-induced causes. Our understanding of the relations between the south Florida ecosystem and introduced forces will allow managers to make informed decisions regarding the south Florida ecosystem restoration and monitoring. The record of past ecosystem conditions can be found in shallow sediment cores. This U.S. Geological Survey Open-File Report describes six shallow sediment cores collected from Biscayne Bay. The cores described herein are being processed for a variety of analytical procedures, and this provides the descriptive framework for future analyses of the included cores. This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

A carbon, nitrogen, and sulfur elemental and isotopic study in dated sediment cores from the Louisiana Shelf

USGS Publications Warehouse

Rosenbauer, R.J.; Swarzenski, P.W.; Kendall, C.; Orem, W.H.; Hostettler, F.D.; Rollog, M.E.

2009-01-01

Three sediment cores were collected off the Mississippi River delta on the Louisiana Shelf at sites that are variably influenced by recurring, summer-time water-column hypoxia and fluvial loadings. The cores, with established chronology, were analyzed for their respective carbon, nitrogen, and sulfur elemental and isotopic composition to examine variable organic matter inputs, and to assess the sediment record for possible evidence of hypoxic events. Sediment from site MRJ03-3, which is located close to the Mississippi Canyon and generally not influenced by summer-time hypoxia, is typical of marine sediment in that it contains mostly marine algae and fine-grained material from the erosion of terrestrial C4 plants. Sediment from site MRJ03-2, located closer to the mouth of the Mississippi River and at the periphery of the hypoxic zone (annual recurrence of summer-time hypoxia >50%), is similar in composition to core MRJ03-3, but exhibits more isotopic and elemental variability down-core, suggesting that this site is more directly influenced by river discharge. Site MRJ03-5 is located in an area of recurring hypoxia (annual recurrence >75%), and is isotopically and elementally distinct from the other two cores. The carbon and nitrogen isotopic composition of this core prior to 1960 is similar to average particulate organic matter from the lower Mississippi River, and approaches the composition of C3 plants. This site likely receives a greater input of local terrestrial organic matter to the sediment. After 1960 and to the present, a gradual shift to higher values of ??13C and ??15N and lower C:N ratios suggests that algal input to these shelf sediments increased as a result of increased productivity and hypoxia. The values of C:S and ??34S reflect site-specific processes that may be influenced by the higher likelihood of recurring seasonal hypoxia. In particular, the temporal variations in the C:S and ??34S down-core are likely caused by changes in the rate of sulfate reduction, and hence the degree of hypoxia in the overlying water column. Based principally on the down-core C:N and C:S ratios and ??13C and ??34S profiles, sites MRJ03-3 and MRJ03-2 generally reflect more marine organic matter inputs, while site MRJ03-5 appears to be more influenced by terrestrial deposition. ?? 2009 Springer-Verlag.

A sampler for coring sediments in rivers and estuaries

USGS Publications Warehouse

Prych, Edmund A.; Hubbell, D.W.

1966-01-01

A portable sampler developed to core submerged unconsolidated sediments collects cores that are 180 cm long and 4.75cm in diameter. The sampler is used from a 12-m boat in water depths up to 20 m and in flow velocities up to 1.5m per second to sample river and estuarine deposits ranging from silty clay to medium sand. Even in sand that cannot be penetrated with conventional corers, the sampler achieves easy penetration through the combined application of vibration, suction, and axial force. A piston in the core barrel creates suction, and the suspension system is arranged so that tension on the support cable produces both a downward force on the core barrel and a lateral support against overturning. Samples are usually retained because of slight compaction in the driving head; as a precaution, however, the bottom of the core barrel is covered by a plate that closes after the barrel is withdrawn from the bed. Tests show that sample-retainers placed within the driving head restrict penetration and limit core lengths. Stratification within cores is disrupted little as a result of the sampling process.

Distribution and sources of carbon, nitrogen, phosphorus and biogenic silica in the sediments of Chilika lagoon

NASA Astrophysics Data System (ADS)

Nazneen, Sadaf; Raju, N. Janardhana

2017-02-01

The present study investigated the spatial and vertical distribution of organic carbon (OC), total nitrogen (TN), total phosphorus (TP) and biogenic silica (BSi) in the sedimentary environments of Asia's largest brackish water lagoon. Surface and core sediments were collected from various locations of the Chilika lagoon and were analysed for grain-size distribution and major elements in order to understand their distribution and sources. Sand is the dominant fraction followed by silt + clay. Primary production within the lagoon, terrestrial input from river discharge and anthropogenic activities in the vicinity of the lagoon control the distribution of OC, TN, TP and BSi in the surface as well as in the core sediments. Low C/N ratios in the surface sediments (3.49-3.41) and cores (4-11.86) suggest that phytoplankton and macroalgae may be major contributors of organic matter (OM) in the lagoon. BSi is mainly associated with the mud fraction. Core C5 from Balugaon region shows the highest concentration of OC ranging from 0.58-2.34%, especially in the upper 30 cm, due to direct discharge of large amounts of untreated sewage into the lagoon. The study highlights that Chilika is a dynamic ecosystem with a large contribution of OM by autochthonous sources with some input from anthropogenic sources as well.

Evolution of the anthropogenic impact in the Augusta Harbor (Eastern Sicily, Italy) in the last decades: benthic foraminifera as indicators of environmental status.

PubMed

Romano, Elena; Bergamin, Luisa; Ausili, Antonella; Celia Magno, Maria; Gabellini, Massimo

2016-06-01

The study of benthic foraminifera in sediment cores provides the opportunity to recognize environmental changes, including those due to the anthropogenic impact. The integration of these data with chemical-physical parameters provides a comprehensive quality assessment. This research was applied to a sediment core collected in the Augusta bay, where a very large commercial and military harbor and one of the largest petrochemical poles in Europe are present. Inside the petrochemical area also operated, from 1958 to 2003, a chlor-alkali plant with mercury cell technology which caused anthropic contamination of surrounding land and marine areas. The sediment core was collected in front of this plant and characterized for grain size and pollutants directly associated to chlor-alkali activity, such as mercury (Hg), barium (Ba), polychlorobiphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs). Composition of foraminiferal assemblages and faunal parameters such as specific diversity, faunal density, abundance of abnormal specimens, and foraminiferal size were investigated as potential indicators of environmental status. Statistical analysis indicated a main common origin for Hg, Ba, and PCBs and the influence of pollutants on species distribution and faunal diversity and density. Exceptionally high Hg concentrations (63-680 mg/kg d.w.) were recorded in the whole core, where the geochronological study attributed the most contaminated levels to the period of maximum activity of the chlor-alkali plant, while a decrease of contamination was recorded after the stop of the activity. Distinct foraminiferal assemblages identified different ecozones along the core, which suggested decreasing anthropogenic impact from the bottom to the top.

Inorganic geochemical indicators of glacial-interglacial changes in productivity and anoxia on the California continental margin

USGS Publications Warehouse

Dean, W.E.; Gardner, J.V.; Piper, D.Z.

1997-01-01

Evidence from sediments in cores collected from within the present oxygen-minimum zone (OMZ; 600-1200 m) on the central and northern California margins record several episodes during the last interstadial (OIS-3, ca. 60-24 ka) of deposition of laminated sediments containing elevated concentrations of several trace elements indicative of anoxic conditions (e.g., Mo, Ni, Zn, and Cu). The presence of abundant well-preserved organic matter, as well as lack of bioturbation and the presence of elevated concentrations of Mo and other trace elements, all support the theory that the OMZ in the northeastern Pacific Ocean was more intense, possibly anoxic, at several times during the late Pleistocene. Sediments of all ages in cores from the southern California margin contain elevated concentrations of Mo, suggesting that this area has always had higher rates of sulfate reduction than either the central or northern California areas. Most of the Ba in sediments in all cores collected on the upper continental slope (200-2700 m) off California and southern Oregon is derived from detrital clastic material, and this source did not change much in time. However, the amount of biogenic Ba did vary with time, and these variations closely follow the temporal variations in organic C (Corg) mass accumulation rate. Using Ba and Corg mass accumulation rates as proxy variables for productivity, all cores show that organic productivity under the California Current upwelling system was highest during OIS-3 and the Holocene, and lowest during the last glacial interval (LGI, ca. 24-10 ka). All paleoproductivity proxy variables indicate that the southern California area has always experienced higher productivity than other areas under the California Current, at least over the last 50 ky. Copyright ?? 1997 Elsevier Science Ltd.

Sediment lithology and radiochemistry from the back-barrier environments along the northern Chandeleur Islands, Louisiana—March 2012

USGS Publications Warehouse

Marot, Marci E.; Smith, Christopher G.; Adams, C. Scott; Richwine, Kathryn A.

2017-04-11

Scientists from the U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center collected a set of 8 sediment cores from the back-barrier environments along the northern Chandeleur Islands, Louisiana, in March 2012. The sampling efforts were part of a larger USGS study to evaluate effects on the geomorphology of the Chandeleur Islands following the construction of an artificial sand berm to reduce oil transport onto federally managed lands. The objective of this study was to evaluate the response of the back-barrier tidal and wetland environments to the berm. This report serves as an archive for sedimentological and radiochemical data derived from the sediment cores. The data described in this report are available for download on the data downloads page.

New Progress on Radiocarbon Geochronology in Southern Lake Tanganyika (East Africa)

NASA Astrophysics Data System (ADS)

McGlue, M. M.; Soreghan, M. J.

2017-12-01

Our limnogeological research in Lake Tanganyika focuses on elucidating the patterns of sediment accumulation on deepwater horsts, outer platforms, and littoral environments in the lake's southern basin ( 6-8°S latitude). Here, we present new radiocarbon (14C) dates from high-quality surface sediment cores, in order to make comparisons with previously published age models, to address the presence and spatiotemporal variability of a reservoir effect, and to constrain sedimentation rates and facies at sites that may be important targets for future scientific drilling. Plant macrofossils are rare in deepwater sediment cores, so charcoal and bulk organic matter have been the primary materials used for dating. On the Kavala Island Ridge (KIR) horst, initial core descriptions revealed variations in laminae presence, thickness, and chemistry. Sediment cores from the KIR at 172m water depth consist of thickly laminated diatom oozes. Charcoal from the bases of these cores returned median ages of 2.1-2.2 cal ka, suggesting linear accumulation rates on the order of 0.51 mm/yr. By contrast, a core from 420 m water depth on the KIR exhibited very thin laminations and diatom layers were much less prominent. Charcoal at the base of this core produced a median age of 8.1 cal ka, suggesting a linear accumulation rate of 0.11 mm/yr. These initial results suggest that sedimentation rates may vary considerably over sublacustrine horst blocks. We will test this initial discovery with additional sedimentation rate information from the Kalya and Nitiri horsts. In addition, we report new 14C dates made on both dead and live-collected shells of the endemic gastropod Neothauma tanganyicense. These shells form vast accumulations along shallow-water platforms of the lake and form an important substrate for a number of other endemic species. The discovery of living snails in southern Lake Tanganyika may allow for the development of a species-specific reservoir correction. A limited N. tanganyicense shell 14C dataset from the lake's northern basin exhibits time averaged over the past 1600 cal yrs; results from this project will begin to address spatial variability in time averaging, and therefore improve our understanding of shell bed formation and the extent to which anthropogenic sedimentation is impacting shell bed persistence.

A tale of two cores: Evaluation of 210Pb dating methods of salt marsh sediments for two cores collected 30 years apart

NASA Astrophysics Data System (ADS)

Fuller, C.; Drexler, J. Z.

2016-12-01

210Pb dating of wetland sediments is commonly used to constrain recent C accumulation rates and contaminant input histories. However, uncertainties in 210Pb-derived rates and validation of accumulation and accretion rates using an independent tracer are often not reported. We describe here 210Pb and 137Cs profiles in two cores from a salt marsh in south San Francisco Bay, California, collected in 1981 and 2011 within 5 m of each other, to compare and evaluate 210Pb dating methods. In the 1981 core, unsupported 210Pb (210PbXS) was detected to 12 cm and yielded mass accumulation rates (MAR) of 0.043 and 0.036 g/cm2/y using the Constant Flux-Constant Sedimentation method (CF:CS) and Constant Rate of Supply (CRS) methods, respectively. Accretion rates (S) of 0.17 (CF:CS) and 0.12 cm/y (CRS) were calculated from these MARs. The distinct 137Cs peak at 4-6 cm in the 1981 core is in good agreement with the210Pb-based 1963 depth (3.4 and 4 cm, CF:CS and CRS, respectively). 210PbXS was detectable to 18 cm in the 2011 core, and yielded a CF:CS MAR (0.077 g/cm2/y; S = 0.35 cm/y) that is about two times greater than the mass-weighted average CRS MAR (0.044 g/cm2/y; S = 0.16 cm/y). Broad subsurface maxima in 137Cs and 239Pu were observed between 16 and 24 cm in the 2011 core, which are 5 to 11 cm deeper than the 1963 depth calculated by the 2011 and 1981 210Pb-derived MARs. The apparent migration and broadening of bomb-fallout radionuclide peaks over 30 years negates their use in validating 210Pb dating. Because of low 210PbXS activities in both cores, the base of the 210PbXS profile and integrated activity used in CRS are underestimated, resulting in the lower CRS MARs that decrease with increasing depth. The range of MARs determined for two cores within 5 m but separated by 30 years will be used as an example to evaluate the uncertainties that need to be reported with C accumulation rates and contaminant histories derived from 210Pb dating of sediment archives.

Methane Hydrate Recovered From A Mud Volcano in Santa Monica Basin, Offshore Southern California

NASA Astrophysics Data System (ADS)

Normark, W. R.; Hein, J. R.; Powell, C. L.; Lorenson, T. D.; Lee, H. J.; Edwards, B. D.

2003-12-01

In July 2003, a short (2.1 m) piston core from the summit of a mud volcano recovered methane hydrate at a water depth of 813 m in Santa Monica Basin. The discovery core penetrated into in the hydrate as evidenced by chunks of ice and violent degassing of the core section between 162 and 212 cm depth. The core consists of shell hash and carbonate clasts (to 7-cm long) in silty mud. The methanogenic carbonates are of two types: massive, recrystallized nodular masses with an outer mm-thick sugary patina and a bivalve coquina with carbonate cement. Living clams including the genus Vesicomya, commonly found at cold-seep sites elsewhere, were recovered from the top of the core. Further sampling attempts using piston, gravity, and box corers, all of which were obtained within 15 m of the discovery core, recovered olive-brown silty mud with variable amounts of whole and fragmented bivalve shells and methanogenic carbonate fragments characteristic of cold-seep environments. Gases collected in cores adjacent to the discovery core contain elevated amounts of methane and trace amounts of heavier hydrocarbon gases, indicating some component from thermogenic sources. Hydrogen sulfide was also detected in these sediment samples. Vertical channels in one core may have served as fluid pathways. The existence of hydrate at such a shallow depth in the sediment was unexpected, however, the presence of Vesicomya and hydrogen sulfide indicate that the mud volcano is a site of active methane venting. The mud volcano, which is about 24 km west-southwest of Redondo Beach, is about 300 m in diameter at the base. No internal structure is resolved on either high resolution deep-tow boomer or single-channel air-gun profiles, most likely as a result of the gas content and sediment deformation. The diapiric structure has ascended through well-bedded sediment on the lower slope of the basin, producing as much as 30 m of bathymetric relief. It is located in an area where strike-slip motion along the San Pedro Basin fault zone to the south is replaced by convergent motion to the north. The source horizon for the gas in the hydrate is unknown but appears to be collecting in beds as shallow as 200 m below the regional seafloor based on the presence of a strong and irregular reflection interval.

Revisiting Atmospheric Lead in NYC - Comparison of Archived Air Filters to Urban Park Sediments and Soils

NASA Astrophysics Data System (ADS)

Chillrud, S. N.; Ross, J. M.; Yan, B.; Bopp, R.

2015-12-01

Urban lake sediments have the potential to be used for reconstructing history of aerosols, providing data before the start of urban air quality monitoring. In a previous study, the similarity between radionuclide and excess Pb inventories (57 g/m^2) in Central Park Lake (CPL) sediments and those same parameters in Central Park soils (CPS) was interpreted to indicate that urban lake sediment cores from CPL represent deposition of atmospheric aerosols over the history of the park, which was constructed in the 1860s. Furthermore, metal ratios and metal chronologies indicated that incineration was the major source of Pb to the NYC atmosphere over the 20th century. In this report, we compare the lake chronologies for metals to a set of archived air filters collected by the Department of Energy's Environmental Measurement Lab (EML). These weekly filters of total suspended particulates (TSP) were collected by a high volume sampler located in lower Manhattan for radionuclides as part of the program focused on documenting radioactive fallout from nuclear weapons testing. Metal concentrations measured in subsamples of the EML filters collected between the 1970s to 1990s showed Pb decreasing more slowly than the records of Pb added to gasoline. Metal ratios in the filters were similar to the ratios measured in CPL sediments; the Pb to Sn ratios were roughly 20:1 and the Pb to Zn ratios were in close to 1. The similarity of the ratios provides additional solid support that the CP Lake sediment cores reflect atmospheric inputs. The enrichment of Pb in the large aerosol particle fraction (TSP), relative to fine PM2.5 fraction, demonstrates that the resuspended NYC soils and their historical contaminant burden, are the primary, current source of Pb to NYC air.

Vertical accumulation of potential toxic elements in a semiarid system that is influenced by an abandoned gold mine

NASA Astrophysics Data System (ADS)

Sánchez-Martínez, Martha A.; Marmolejo-Rodríguez, Ana J.; Magallanes-Ordóñez, Víctor R.; Sánchez-González, Alberto

2013-09-01

The mining zone at El Triunfo, Baja California Sur, Mexico, was exploited for gold extraction for 200 years. This area includes more than 100 abandoned mining sites. These sites contain mine tailings that are highly contaminated with potential toxic elements (PTE), such as As, Cd, Pb, Sb, Zn, and other associated elements. Over time, these wastes have contaminated the sediments in the adjacent fluvial systems. Our aim was to assess the vertical PTE variations in the abandoned mining zone and in the discharge of the main arroyo into a small lagoon at the Pacific Ocean. Sediments were collected from the two following locations in the mining zone near the arroyo basin tailings: 1) an old alluvial terrace (Overbank) and a test pit (TP) and 2) two sediment cores locations at the arroyo discharge into a hypersaline small lagoon. Samples were analyzed by ICP-MS, ICP-OES, and INAA and the methods were validated. The overbank was the most contaminated and had As, Cd, Pb, Sb, and Zn concentrations of 8690, 226, 84,700, 17,400, and 42,600 mg kg-1, respectively, which decreased with depth. In addition, the TP contained elevated As, Cd, Pb, Sb, and Zn concentrations of 694, 18.8, 5001, 39.2, and 4170 mg kg-1, respectively. The sediment cores were less contaminated. However, the As, Cd, Pb, Sb, and Zn concentrations were greater than the concentrations that are generally found in the Earth's crust. The normalized enrichment factors (NEFs), which were calculated from the background concentrations of these elements in the system, showed that extremely severe As, Cd, Pb, Sb, and Zn (NEF > 50) enrichment occurred at the overbank. The TP was severe to very severely enriched with As, Cd, Pb, Sb, and Zn (NEF = 10-50). The sediment cores had a severe enrichment of As, Pb, and Zn (NEF = 10-25). Their vertical profiles showed that anthropogenic influences occurred in the historic sediment deposition at the overbank and TP and in the sediment cores. In addition, the As, Pb, and Zn concentrations in the sediment cores were related to the deposition of fine sediments and organic carbon.

Evaluation of metals and hydrocarbons in sediments from a tropical tidal flat estuary of Southern Brazil.

PubMed

Costa, Eduardo S; Grilo, Caroline F; Wolff, George A; Thompson, Anu; Figueira, Rubens Cesar Lopes; Neto, Renato Rodrigues

2015-03-15

Although the Passagem Channel estuary, Espírito Santo State, Brazil, is located in an urbanized and industrialized region, it has a large mangrove system. Here we examined natural and anthropogenic inputs that may influence trace metal (Cd, Cr, Cu, Ni, Sc, Pb and Zn) and hydrocarbon (n-alkane and terpane) deposition in three sediment cores collected in the tidal flat zone of the estuary. The cores were also analyzed for carbonate, grain size and stable isotopic composition (δ(13)Corg. and δ(15)Ntotal). Metal enrichment and its association to petroleum hydrocarbons in the surficial sediments of one of the cores, indicate crude oil and derivative inputs, possibly from small vessels and road run-off from local heavy automobile traffic. At the landward sites, the major contributions for metals and hydrocarbons are from natural sources, but in one case, Cu may have been enriched by domestic effluent inputs. Copyright © 2014 Elsevier Ltd. All rights reserved.

Current and historical concentrations of poly and perfluorinated compounds in sediments of the northern Great Lakes - Superior, Huron, and Michigan.

PubMed

Codling, Garry; Hosseini, Soheil; Corcoran, Margaret B; Bonina, Solidea; Lin, Tian; Li, An; Sturchio, Neil C; Rockne, Karl J; Ji, Kyunghee; Peng, Hui; Giesy, John P

2018-05-01

Current and historical concentrations of 22 poly- and perfluorinated compounds (PFASs) in sediment collected from Lake Superior and northern Lake Michigan in 2011 and Lake Huron in 2012 are reported. The sampling was performed in two ways, Ponar grabs of surface sediments for current spatial distribution across the lake and dated cores for multi-decadal temporal trends. Mean concentrations of the sum of PFASs (∑PFASs) were 1.5, 4.6 and 3.1 ng g -1 dry mas (dm) in surface sediments for Lakes Superior, Michigan and Huron, respectively. Of the five Laurentian Lakes, the watersheds of Superior and Huron are the less densely populated by humans, and concentrations observed were typically less and from more diffuse sources, due to lesser urbanization and industrialization. However, some regions of greater concentrations were observed and might indicate more local, point sources. In core samples concentrations ranged from 7 that include perfluoro-n-octane sulfonate (PFOS) bind more strongly to sediment, which resulted in more accurate analyses of temporal trends. Shorter-chain PFASs, such as perfluoro-n-butanoic acid which is the primary replacement for C8 PFASs that have been phased out, are more soluble and were identified in some core layers at depths corresponding to pre-production periods. Thus, analyses of temporal trends of these more soluble compounds in cores of sediments were less accurate. Total elemental fluorine (TF) and extractable organic fluorine (EOF) indicated that identified PFASs were not a significant fraction of fluorine containing compounds in sediment (<0.01% in EOF). Copyright © 2018 Elsevier Ltd. All rights reserved.

Glacial-marine sediments record ice-shelf retreat during the late Holocene in Beascochea Bay on the western margin of the Antarctic Peninsula

NASA Astrophysics Data System (ADS)

Hardin, L. A.; Wellner, J. S.

2010-12-01

Beascochea Bay has an overall rapid rate of sedimentation due to retreating fast-flowing ice, and thus contains high-resolution records of Antarctica’s glacial and climate history. Beascochea Bay is a 16 km long by 8 km wide bay located on the western margin of the Antarctica Peninsula, centered between Anvers Island and Renaud Island, but open to the Bellingshausen Sea. Currently, three tidewater glaciers draining the Bruce Plateau of Graham Land enter into the fjords of Beascochea Bay, releasing terrigenous sediments which have left a record of the fluctuations of the Antarctic Peninsula Ice Cap since the grounded ice decoupled from the seafloor after the last glacial maximum. These three glaciers have played a significant role in providing sediment to the main basin, allowing a detailed sediment facies analysis to be conducted from eight sediment cores which were collected during the austral summer of 2007. Pebbly silty clay sediment cores, along with 3.5 kHz seismic data and multibeam swath bathymetry data, are integrated to reconstruct a glacial retreat timeline for the middle to late Holocene, which can be compared to the recent retreat rates over the last century. Paleoenvironment of deposition is determined by mapping lateral facies changes from the side fjords (proximal) to the outer basin (distal), as each region records the transition from glacial-marine sediments to open-marine sediments. As the ice retreated from the outer basin to the inner basin, and most recently leaving the side fjords, each facies deposited can be age-constrained by radiocarbon, 210Pb, and 137Cs dating methods. A distinct 137Cs signal is readily seen in two kasten cores from a side fjord and the inner basin of Beascochea Bay. This dating method revealed an average sedimentation rate of 2.7 mm per year for approximately the last century, which is comparable to 210Pb rates obtained in other studies. Lithology variations in each sediment core record indications of ice-shelf influence in Beascochea Bay throughout the Holocene deglaciation. The distinctively laminated sub-ice shelf facies can be clearly seen in the x-rays of these cores, and can be easily distinguished from the poorly sorted glacial-marine facies and the greenish finer-grained facies deposited in open-marine conditions. A 14 m long sediment core taken from the outer basin of Beascochea Bay recovered the greatest length of sediment and dates back to the middle Holocene. X-rays of this core show a possible mid-Holocene retreat of the ice shelf followed by intermittent advance and retreat that precedes the most recent retreat. The inner basin of Beascochea Bay has been without an ice shelf for the last 200 years, based on the sedimentation rates of the last century projected downcore.

Late to middle Pleistocene Arctic glacial history implied from a sedimentary record from the Northwind Ridge

NASA Astrophysics Data System (ADS)

Liu, Y.; Dong, L.; Shi, X.; Zhu, A.

2017-12-01

Abstract: Sediment core ARC6-C21 collected from the Northwind Ridge, western Arctic Ocean, covers the late to middle Quaternary (Marine Isotope Stages (MIS) 1-11), as estimated by correlation to earlier proposed Arctic Ocean stratigraphies and AMS14C dating of the youngest sediments. Detailed examination of the elemental composition of sediment along with grain size in core ARC6-C21 provides important new information about sedimentary environments and provenance. We use increased contents of coarse debris as an indicator of glacier collapse events at the margins of the western Arctic Ocean, and identify the provenance of these events from geochemical composition. Notably, peaks of MgO and CaO, including large dropstones, presumably track the Laurentide Ice Sheet (LIS) discharge events to the Arctic Ocean. Major LIS inputs occurred during the stratigraphic intervals estimated as MIS 3, intra-MIS 5 and 7 events, MIS 8, and MIS 10. Inputs from the East Siberian Ice Sheet (ESIS) and/or Eurasia Ice Sheet (EIS)are inferred from peaks of SiO2, K2O and Na2O associated with coarse sediment. Major ESIS and/or EIS sedimentary events occurred in the intervals estimated as MIS 2, MIS 4, MIS 6, MIS 8 and MIS 10. Keywords: Sediment core, Pleistocene, western Arctic Ocean, geochemistry, grain size, sediment provenance, glaciations

Heavy metal accumulation during the last 30 years in the Karnaphuli River estuary, Chittagong, Bangladesh.

PubMed

Wang, Ai-Jun; Kawser, Ahmed; Xu, Yong-Hang; Ye, Xiang; Rani, Seema; Chen, Ke-Liang

2016-01-01

Heavy metal contamination of aquatic environment has attracted global attention owing to its abundance, persistence, and environmental toxicity, especially in developing countries like Bangladesh. Five heavy metals, namely chromium (Cr), copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn) were investigated in surface and core sediments of the Karnaphuli River (KR) estuary in Chittagong, Bangladesh, in order to reveal the heavy metal contamination history in estuarine sediments and its response to catastrophic events and human activities. The surface sediment was predominantly composed of silt and sand, and the surface sediment was contaminated with Cr and Pb. Based on the 210 Pb chronology, the sedimentation rate in the inter-tidal zone of KR estuary was 1.02 cm/a before 2007, and 1.14 cm/a after 2008. The core sediment collected from 8 to 20 cm below the surface mainly originated from terrestrial materials induced by catastrophic events such as cyclone, heavy rainfall and landslides in 2007 and 2008. The values of contamination factor ( CF ) showed that the sediment became moderately contaminated with Cr and Pb in the last 30 years. The variation and accumulation of heavy metals in core sediment before 2000 was mainly related to natural variations in sediment sources; however, in subsequent years, the anthropogenic inputs of heavy metals have increased due to rapid physical growth of urban and industrial areas in the Chittagong city. In general, the accumulation pattern of heavy metals after normalization to Aluminum in sediments of KR estuary indicated an accelerated rate of urbanization and industrialization in the last 30 years, and also suggested the influence of natural catastrophic event on estuarine environment.

Surface sediment remobilization triggered by earthquakes in the Nankai forearc region

NASA Astrophysics Data System (ADS)

Okutsu, N.; Ashi, J.; Yamaguchi, A.; Irino, T.; Ikehara, K.; Kanamatsu, T.; Suganuma, Y.; Murayama, M.

2017-12-01

Submarine landslides triggered by earthquakes generate turbidity currents (e.g. Piper et al., 1988; 1999). Recently several studies report that the remobilization of the surface sediment triggered by earthquakes can also generate turbidity currents. However, studies that proposed such process are still limited (e.g. Ikehara et al., 2016; Mchugh et al., 2016; Moernaut et al., 2017). The purpose of this study is to examine those sedimentary processes in the Nankai forearc region, SW Japan using sedimentary records. We collected 46 cm-long multiple core (MC01) and a 6.7 m-long piston core (PC03) from the small basin during the R/V Shinsei Maru KS-14-8 cruise. The small confined basin, which is our study site, block the paths of direct sediment supply from river-submarine canyon system. The sampling site is located at the ENE-WSW elongated basin between the accretionary prism and the forearc basin off Kumano without direct sediment supply from river-submarine canyon system. The basin exhibits a confined basin that captures almost of sediments supplied from outside. Core samples are mainly composed of silty clay or very fine sand. Cs-137 measurement conducted on a MC01 core shows constantly high value at the upper 17 cm section and no detection below it. Moreover, the sedimentary structure is similar to fine-grained turbidite described by Stow and Shanmgam (1980), we interpret the upper 17 cm of MC01 as muddy turbidite. Grain size distribution and magnetic susceptibility also agree to this interpretation. Rapid sediment deposition after 1950 is assumed and the most likely event is the 2004 off Kii peninsula earthquakes (Mw=6.6-7.4). By calculation from extent of provenance area, which are estimated by paleocurrent analysis and bathymetric map, and thickness of turbidite layer we conclude that surface 1 cm of slope sediments may be remobilized by the 2004 earthquakes. Muddy turbidites are also identified in a PC03 core. The radiocarbon age gap of 170 years obtained around 2 mbsf of PC03 core also indicates similar sedimentary process. However, we also obtained large age gap in a thick turbidite layer, indicating remobilization of deeper sediments by landslide. Our results revealed that the studied basin recorded various scales and styles of sediment remobilizations by earthquake shakings.

Historical sediment record and levels of PCBs in sediments and mangroves of Jobos Bay, Puerto Rico.

PubMed

Alegria, Henry; Martinez-Colon, Michael; Birgul, Askin; Brooks, Gregg; Hanson, Lindsey; Kurt-Karakus, Perihan

2016-12-15

Polychlorinated biphenyls (PCBs) were quantified in 18 surface sediment samples, 1 sediment core, and several mangrove tissue samples collected in Jobos Bay, Puerto Rico in September 2013. Total PCBs in surface sediments ranged from 0.42 to 1232ngg -1 dw. Generally, higher levels were observed near-shore close to urban and industrial areas. The levels suggest significant pollution in Jobos Bay with respect to PCBs. Two-thirds of the sites were dominated by lighter PCB congeners (tri- to penta-chlorinated PCBs) while one-third had heavy PCB congeners (hexa- to octa-chlorinated PCBs) dominant. Total PCBs in a sediment core indicated levels fluctuating according to historical usage patterns. Total PCBs were measured in mangal leaves (14-747ngg -1 dw), roots (0.26-120ngg -1 dw), and seeds (16-93ngg -1 dw), suggesting bioaccumulation from sediments. This is the first report of a historical profile of PCBs in the study area and of PCB bioaccumulation in mangroves. This article provides new and useful information on PCBs in the Caribbean area of the GRULAC region. Copyright © 2016 Elsevier B.V. All rights reserved.

Current status and historical trends of organochlorine pesticides in the ecosystem of Deep Bay, South China

NASA Astrophysics Data System (ADS)

Qiu, Yao-Wen; Zhang, Gan; Guo, Ling-Li; Cheng, Hai-Rong; Wang, Wen-Xiong; Li, Xiang-Dong; Wai, Onyx W. H.

2009-11-01

To characterize the current status and historical trends in organochlorine pesticides (OCPs) contamination in Deep Bay, an important water body between Hong Kong and mainland China with a Ramsar mangrove wetland (Maipo), samples from seawater, suspended particulate matter (SPM), surface sediment, sediment core and fish were collected to determine the OCPs concentrations. Sediment core dating was accomplished using the 210Pb method. The average concentrations of DDTs, HCHs and chlordanes in water were 1.96, 0.71, 0.81 ng l -1, while in SPM were 36.5, 2.5, 35.7 ng g -1 dry weight, in surface sediment were 20.2, 0.50, 2.4 ng g -1 dry weight, and in fish were 125.4, 0.43, 13.1 ng g -1 wet weight, respectively. DDTs concentrations in various matrices of Deep Bay were intermediate compared with those in other areas. Temporal trends of the targeted OCPs levels in sediment core generally increased from 1948 to 2004, with the highest levels in top or sub-surface sediment. Both DDT composition and historical trends indicated an ongoing fresh DDT input. A positive relationship between the bioconcentration factor (BCF) of target chemicals and the corresponding octanol-water partition coefficient ( Kow), and between the biota-sediment accumulation factors (BSAF) and the Kow were observed in the Bay. The risk assessment indicated that there were potential ecological and human health risks for the target OCPs in Deep Bay.

Sedimentology, stratigraphy and chronology of a decantation tank in the sewer network of Orléans (France).

NASA Astrophysics Data System (ADS)

Jacob, Jérémy; Thibault, Alexandre; Simonneau, Anaëlle; Le Milbeau, Claude; DiGiovanni, Christian; Sabatier, Pierre; Reyss, Jean-Louis; Ardito, Luigi; Morio, Cédric

2017-04-01

Current debates on the status of the Anthropocene convey geologists and palaeoenvironmentalists toward new spatial and temporal targets. One of the most emblematic socio-ecosystem of the Anthropocene is urban areas in which the dynamics of materials are mainly controlled by human activities. This brings unprecedented elemental, molecular and isotopic concentrations and distributions that lead Norra (2009) to propose a new geological sphere: the Astysphere. Here we propose that sediments accumulated in sewer networks can provide original, integrated, and multi-thematic archives for the recent history of cities by considering urban systems as any catchment where materials are produced, transported and sedimented. The study site is a decantation tank that collects stormwater and wastewater from the north of Orléans city, upstream wastewater plants in Orléans. Sediments accumulated since 1942 over 17 m depth and were never cleaned out until 2015. Two sedimentary cores of 70 (A) and 250 cm long (B) were collected before clean out and then a third of 150 cm (C) after. Sediments are organized into layers constituted by sands and gravels alternating with silts and organic layers. Sharp contacts between those layers indicate evenemential sedimentation, as expected in sewer networks. We formulate the hypothesis that organic/mineral alternations result from a seasonal dynamic. 7Be presence in topmost sample from core A confirms it was deposited within the last 6 months. In core C, only the upper half core, mostly mineral, displays significant 7Be levels whereas 7Be is absent from the lower half, which is mostly organic. This would confirm that our hypothesis of a seasonal alternation, with organic facies deposited during spring- summer and mineral facies deposited during fall-winter. 30 14C dates measured on cores A and B by postbomb method are logically distributed with depth, the most ancient (beginning of the eighties) being recorder at 2.5m depth. This study shows that sediments accumulated in a decantation tank constitute sedimentary archives comparable to more natural ones, thus allowing palaeoenvironmental reconstructions for the Anthropocene. We are currently examining the mineral and organic content of this archive to provide a detailed chronology of the history of man-made materials (drugs, plastics, pesticides…) in urban contexts.

Sedimentation in mountain streams: A review of methods of measurement

USGS Publications Warehouse

Hedrick, Lara B.; Anderson, James T.; Welsh, Stuart A.; Lin, Lian-Shin

2013-01-01

The goal of this review paper is to provide a list of methods and devices used to measure sediment accumulation in wadeable streams dominated by cobble and gravel substrate. Quantitative measures of stream sedimentation are useful to monitor and study anthropogenic impacts on stream biota, and stream sedimentation is measurable with multiple sampling methods. Evaluation of sedimentation can be made by measuring the concentration of suspended sediment, or turbidity, and by determining the amount of deposited sediment, or sedimentation on the streambed. Measurements of deposited sediments are more time consuming and labor intensive than measurements of suspended sediments. Traditional techniques for characterizing sediment composition in streams include core sampling, the shovel method, visual estimation along transects, and sediment traps. This paper provides a comprehensive review of methodology, devices that can be used, and techniques for processing and analyzing samples collected to aid researchers in choosing study design and equipment.

Paper plant effluent revisited-southern Lake Champlain, Vermont and New York

USGS Publications Warehouse

Haupt, R.S.; Folger, D.W.

1993-01-01

We used geologic and geochemical techniques to document the change with time of the distribution and concentration of contaminated bottom sediments in southern Lake Champlain near an International Paper Company plant. Our work, initiated in 1972, was expanded on behalf of Vermont citizens in a class-action suit against the International Paper Company. To update our 1972-1973 results, we collected nine cores in 1988 upstream and downstream from the paper plant effluent diffuser. Water content, volatile solids, organic carbon, and three ratios, Al/Si, Cl/Si, and S/Si, in addition to megascopic and microscopic observations, were evaluated to identify and trace the distribution of effluent and to measure the thickness of sediment affected by or containing components of effluent. Analyses were carried out on samples from the cores as well as from effluent collected directly from the plant's waste treatment facility. In 1973, two years after the plant opened, we cored near the diffuser; sediment contaminated with effluent was 4.5 cm thick. In 1988, in the same area, sediment contaminated with effluent was 17 cm thick. In 15 years, water content increased from 72 to 85 percent, volatile solids from 7 to 20 percent, and organic carbon from 2 to 12 percent. Cl/Si and S/Si were high only near the diffuser and were zero elsewhere. In the area of the diffuser, contaminated sediment appears to be accumulating at a rate of about 1 cm/yr. At a control location 22 km upstream (south) from the plant, the top, poorly consoli-dated layer was only 1 cm or less thick both in 1973 and in 1988. The class-action suit was settled in favor of the plaintiffs for $5 million. ?? 1993 Springer-Verlag.

Variations in sediment texture on the northern Monterey Bay National Marine Sanctuary continental shelf

USGS Publications Warehouse

Edwards, B.D.

2002-01-01

The storm-protected continental shelf of Monterey Bay, part of the Monterey Bay National Marine Sanctuary, north-central California, is subject to abundant, episodic sediment input from fluvial sources. North of Monterey Bay, conditions of reduced sediment supply combined with the exposed nature of the shelf provide an effective laboratory for studying the contrasting effects of storm- versus fluvial-dominated conditions on modern sedimentation. Textural analyses performed on surface sediment samples collected from more than 380 box cores and MultiCores??? document the existence of a clearly defined mud belt occupying the mid-shelf throughout the region. Inshore sands combined with these mid-shelf muds represent deposits from modern sedimentation processes. In Monterey Bay, where episodic fluvial input from winter storms dominates sedimentation, the mid-shelf mud belt extends across the shelf to the shelf break. North of Monterey Bay, where sediment loads are reduced and both oceanographic and storm processes dominate, the mid-shelf mud belt is bordered by relict sediments occupying the outer shelf. In the study area, mass accumulation rates established by radiochemical studies support the contention that storm-induced along-shelf processes result in northward transport of sediment within the mud belt. The continuity of transport, however, is interrupted by topographic highs which are barriers or inhibitors to sediment transport created by wrench-style tectonics associated with the San Andreas fault system.

Use of reservoir deposits to reconstruct the recent changes in sediment yields from a small granite catchment in the Yimeng Mountain region, China

NASA Astrophysics Data System (ADS)

Zhang, Yunqi; Long, Yi; Li, Bao; Xu, Shujian; Wang, Xiaoli; Liao, Jia

2017-09-01

Information on recent changes in sediment yields from small catchments provides a better understanding of temporal trends in soil loss from certain physical and human-influenced landscapes that have been subjected to recent environmental changes, and will help bridge the current knowledge gap that exists between hillslope erosion and sediment transport in rivers. The Yimeng Mountain region, characterized by alternating granite and limestone, is one of the most susceptible regions to soil erosion in northern China, and has been subjected to intensive anthropogenic activity in recent years. Soil loss from areas underlain by granite is particularly obvious, and is the main sediment source for the Yihe River. In this study, we used reservoir deposits to estimate the changes in sediment yields over the past 50 years from a small catchment underlain by granite, namely the Jiangzhuang catchment in the Yimeng Mountain region. Three cores were collected from the Jiangzhuang Reservoir in the catchment. The activities of 137Cs and 210Pbex at different depths, clay (grain size < 5 μm) contents, and sedimentary organic carbon (SOC) contents in the cores were analysed with reference to human activity and environmental change in the catchment. The chronologies of the cores were established by 137Cs and 210Pbex dating. The area-specific sediment yield (SSY) for different time periods since dam construction was estimated from each core by referring to the original capacity curve of the reservoir. The results indicate that the depth profiles of 137Cs, 210Pbex, clay, and SOC contents in cores from the Jiangzhuang Reservoir reflect the general history of human disturbances on the catchment over the past 50 years. The estimated SSY value from each core for each period ranged from 7.2 ± 2.7 to 23.7 ± 8.3 t ha- 1 y- 1, with a mean of 12.5 ± 4.6 t ha- 1 y- 1. SSY decreased during 1954-1972, and then showed a general tendency to increase. The temporal pattern of the sediment yield largely reflects the history of environmental change influenced by human activity in the catchment.

Comparative Paleomagnetic Study of the Quaternary-Pliocene Sedimentation Rates in the Arctic Basin: First Results

NASA Astrophysics Data System (ADS)

Elkina, D.; Piskarev, A.

2017-12-01

Accurate dating of marine sediments from the Arctic Basin continues to remain a subject of great debates over the last decades. Due to the lack of adequate materials for biostratigraphy, and isotope analyses, paleomagnetic reconstructions came on line here but still yielded ambivalent interpretations. Moreover, sedimentation rates, estimated for isolated morphological features in the Arctic Ocean, are often extended to the whole Basin and, therefore, lead to significant approximations of the sedimentation pattern distribution. Paleomagnetic study of two sediment cores up to 8 meter long, collected at the Mendeleev Rise, and the Lomonosov Ridge, have provided the opportunity to compare sedimentation regimes on these two profound structures of the Arctic Basin. Cores PS72/396 and PS87/023 were carried out along the cruises of RV Polarstern at the Mendeleev Rise (Stein et. al, 2010), and the Lomonosov Ridge (Stein, 2015) respectively. Measurements of natural remanent magnetization (NRM) and anhysteretic remanence (ARM) acquisition with the following alternating field (AF) demagnetization were performed on u-channel samples, obtained from the cores, at the Center for Geo-Environmental Research and Modeling (GEOMODEL) of the Research Park, St. Petersburg State University. According to preliminary results, core PS72/396 has shown a change from positive to negative inclinations at ca. 120 cm below sea floor (cmbsf), prevailed up to ca. 360 cmbsf where it gets back to the positive ones. This trend is comparable with some previous paleomagnetic results, conducted on cores from the Mendeleev Rise (Piskarev et al., 2013; Elkina, 2014). In contrast, for core PS87/023, a relevant drop to negative inclinations can be observed only after 330 cmbsf. That could signify a dramatic difference in sedimentation rates between the sites during the Quaternary and Pliocene. Nevertheless, a rather complicated picture of the AF data assumes effects of secondary overprints, having influenced the initial magnetization pattern for the both regions studied, manifested for the Lomonosov Ridge in great measure. AcknowledgmentsThe current study is conducted in collaboration with the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research.

Sediment cores as archives of historical changes in floodplain lake hydrology.

PubMed

Lintern, Anna; Leahy, Paul J; Zawadzki, Atun; Gadd, Patricia; Heijnis, Henk; Jacobsen, Geraldine; Connor, Simon; Deletic, Ana; McCarthy, David T

2016-02-15

Anthropogenic activities are contributing to the changing hydrology of rivers, often resulting in their degradation. Understanding the drivers and nature of these changes is critical for the design and implementation of effective mitigation strategies for these systems. However, this can be hindered by gaps in historical measured flow data. This study therefore aims to use sediment cores to identify historical hydrological changes within a river catchment. Sediment cores from two floodplain lakes (billabongs) in the urbanised Yarra River catchment (Melbourne, South-East Australia) were collected and high resolution images, trends in magnetic susceptibility and trends in elemental composition through the sedimentary records were obtained. These were used to infer historical changes in river hydrology to determine both average trends in hydrology (i.e., coarse temporal resolution) as well as discrete flood layers in the sediment cores (i.e., fine temporal resolution). Through the 20th century, both billabongs became increasingly disconnected from the river, as demonstrated by the decreasing trends in magnetic susceptibility, particle size and inorganic matter in the cores. Additionally the number of discrete flood layers decreased up the cores. These reconstructed trends correlate with measured flow records of the river through the 20th century, which validates the methodology that has been used in this study. Not only does this study provide evidence on how natural catchments can be affected by land-use intensification and urbanisation, but it also introduces a general analytical framework that could be applied to other river systems to assist in the design of hydrological management strategies. Copyright © 2015 Elsevier B.V. All rights reserved.

Historical trends of metals in the sediments of San Francisco Bay, California

USGS Publications Warehouse

Hornberger, Michelle I.; Luoma, S.N.; VanGeen, A.; Fuller, C.; Anima, R.

1999-01-01

Concentrations of Ag, Al, Cr, Cu, Fe, Hg, Mn, Ni, Pb, V and Zn were determined in six sediment cores from San Francisco Bay (SFB) and one sediment core in Tomales Bay (TB), a reference estuary. SFB cores were collected from between the head of the estuary and its mouth (Grizzly Bay, GB; San Pablo Bay, SP; Central Bay, CB; Richardson Bay, RB, respectively) and ranged in length from 150 to 250 cm. Concentrations of Cr, V and Ni are greater than mean crustal content in SFB and TB sediments, and greater than found in many other coastal sediments. However, erosion of ultramafic rock formations in the watershed appears to be the predominant source. Baseline concentrations of other metals were determined from horizons deposited before sediments were influenced by human activities and by comparing concentrations to those in TB. Baseline concentrations of Cu co-varied with Al in the SFB sediments and ranged from 23.7 ?? 1.2 ??g/g to 41.4 ?? 2.4 ??g/g. Baseline concentrations of other metals were less variable: Ag, 0.09 ?? 0.02 ??g/g; Pb, 5.2 ?? 0.7 ??g/g; Hg, 0.06 ?? 0.01 ??g/g; Zn, 78 ?? 7 ??g/g. The earliest anthropogenic influence on metal concentrations appeared as Hg contamination (0.3-0.4 ??g/g) in sediments deposited at SP between 1850 and 1880, apparently associated with debris from hydraulic gold mining. Maximum concentrations of Hg within the cores were 20 times baseline. Greater inventories of Hg at SP and GB than at RB verified the importance of mining in the watershed as a source. Enrichment of Ag, Pb, Cu and Zn first appeared after 1910 in the RB core, later than is observed in Europe or eastern North America. Maximum concentrations of Ag and Pb were 5-10 times baseline and Cu and Zn concentrations were less than three times baseline. Large inventories of Pb to the sediments in the GB and SP cores appeared to be the result of the proximity to a large Pb smelter. Inventories of Pb at RB are similar to those typical of atmospheric inputs, although influence from the Pb smelter is also suspected. Concentrations of Hg and Pb have decreased since the 1970s (to 0.30 ??g/g and 25 ??g/g, respectively) and were similar among all cores in 1990. Early Ag contamination was perhaps a byproduct of the Pb smelting process, but a modem source of Ag is also indicated, especially at RB and CB.

Sediment texture and metal contamination in the Venice Lagoon (Italy): A snapshot before the installation of the MOSE system

NASA Astrophysics Data System (ADS)

Zonta, Roberto; Botter, Margherita; Cassin, Daniele; Bellucci, Luca Giorgio; Pini, Roberto; Dominik, Janusz

2018-05-01

Sediments of the Venice Lagoon down to 50 cm depth were investigated to assess sediment texture and metal contamination status, before the construction and activation of the MOSE system, which is intended to prevent the periodical flood events affecting the lagoon and the city of Venice. 380 cores were collected in shallow-water areas of the lagoon, and analysed along their vertical profile to determine grain-size distribution and concentrations of some major and trace elements (Al, As, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn), total carbon and organic carbon. Radionuclide analyses (137Cs, 210Pb) were performed on 15 cores in an attempt to establish sediment chronology and determine radionuclide inventories in erosional and depositional areas. On the whole-lagoon scale, strong depletion of particles <31 μm in diameter (from medium silt to clay fractions) was observed in sediments down to 10 cm depth in comparison to deeper layers. This depletion characterised both erosional and depositional areas, and may be caused by increased water dynamics and resuspension of sediment due to anthropogenic activities. The apparent sediment accumulation rate determined with 210Pbxs in depositional areas was estimated at 0.2-0.4 cm y-1. In the majority of cores, 210Pbxs inventories were lower than expected from atmospheric fallout, suggesting its export along with fine particles. The different sediment characteristics in terms of grain-size distribution and organic carbon content observed in the upper layer with respect to the deeper ones reflect the modification of the sedimentary balance in recent years. The loss of fine particles, even from sediments in depositional areas of the northern part of the lagoon, may herald changes in local sediment texture leading to a further depletion of morphodiversity, which in turn may lead to the reduction or loss of important lagoon habitats. On the whole-lagoon scale, the prevalently lithogenic elements (Al, As, Cr, Fe, Mn, Ni) decreased towards the top of the cores, reflecting the depletion of fine particles in the upper sediment layer due to winnowing in non-confined lagoon areas. In contrast, partly anthropogenic elements (Cu, Hg, Pb, Zn) increased up to the subsurface sediment layers (5-10 and/or 10-20 cm) as an effect of increasing pollutant inputs until a certain time in the past. Enrichment Factors (EF) were calculated from 9 cores, comparing concentrations in the "pre-industrial" (>100 years ago) and recent (surface layer, 0-5 cm) sediments. The mostly lithogenic elements were not enriched (EF ˜ 1), whereas the partly anthropogenic elements showed slight (Cu and Pb, EF ˜ 1.2) to significant (Hg and Zn, EF ˜ 2) enrichment. The shallow waters on the landward side (particularly close to freshwater inputs), the area nearby the industrial district of Porto Marghera and a small zone adjacent to the city of Chioggia were identified as the main pollutant accumulation sites. Mercury was the only element potentially harmful for aquatic life. Its concentration in the biologically active surface sediment layer (0-5 cm) exceeded the NOAA Effects Range-Median (ERM) value in 27% of samples, corresponding to 20% of the shallow-water surface area. The collected data set represents a valuable reference for monitoring the impact of the construction and operation of the MOSE system on the sediment features of the Venice Lagoon.

Sedimentology of cores recovered from the Canada Basin of the Arctic Ocean

NASA Astrophysics Data System (ADS)

Edwards, B. D.; Saint-Ange, F.; Pohlman, J.; Higgins, J.; Mosher, D. C.; Lorenson, T. D.; Hart, P.

2011-12-01

Researchers from the United States and Canada are collaborating to understand the tectonic and sedimentary history of the Arctic Ocean between Canada and Alaska. As part of this on-going study, a joint US-Canadian ice breaker expedition operated in parts of the Canada Basin during August 2010. Occasional interruptions of the seismic data acquisition provided the ship time to collect gravity and piston cores at five sites-of-opportunity throughout the basin. High-resolution multibeam bathymetry and chirp sub-bottom profiler data collected immediately prior to coring reveal the fine-scale morphology of each site. Core photographs, X-ray radiographs, and physical property data support the following descriptions. Two piston cores were collected from the Beaufort Sea continental margin in a region of known bottom simulating reflectors (BSRs). Site 1 (2538 m water depth): This core recovered 5.72 m of gas-charged, gray sticky clay and silty-clay from an approximately 1100 m diameter, 130 m high conical mound overlying the crest of a buried anticline. Gas hydrate recovered in the core catcher combined with cracks and voids, methane and other hydrocarbon gasses, pyrite concretions, chemosynthetic clams, carbonate nodules, and soft carbonate masses indicate the likely upward migration of deep-seated fluids. Site 2 (1157 m water depth): This core, positioned 40 km upslope from the gas hydrate core, recovered 3 m of gray sticky silty clay and clayey silt near the base of an erosional scarp. Some voids and fracturing are apparent but carbonate masses and pyrite concretions are absent. Site 3 (3070 m water depth): This core from the top of a seamount discovered in 2009 in the north-central part of the Canada Basin recovered 4.94 m of sediment. More than 3 m of dark brown to yellowish brown, massive interbedded silty clays with sands and matrix-supported gravels (ice rafted debris [IRD]) occur in abrupt contact with underlying reddish yellow to brownish yellow silty clay and gravelly sandy clay interpreted to be altered hydrothermally. Successions of IRD layers create a thinly- to medium-bedded sequence throughout the lower section. Site 4 (3700 m water depth; central Canada Basin): This core recovered 3.4 m of sediment typified by decimeter-thick sequences of stacked graded beds with erosional basal contacts (Bouma sequences) characteristic of turbidite deposition. Site 5 (2081 m water depth; continental slope west of the Canadian archipelago): This core recovered 4.96 m of sediment of which the upper 2 m is silty clay to clayey silt with dispersed sand and granules. This upper section has an irregular, sharp basal contact with an underlying 16-cm-thick clast-supported massive gravel. The gravel has a scoured basal contact and overlies a monotonous gray clayey silt containing dispersed granules of IRD. Sparse and poorly preserved fauna throughout all the cores make age determination difficult; however, given the paucity of sediment cores in the Arctic Ocean, these samples provide vital geophysical groundtruth and sedimentological information about the basin.

Comparison of Radiocarbon Ages of Sediments, Plants, and Shells From Coastal Lakes in North Florida

NASA Astrophysics Data System (ADS)

Wang, Y.; Das, O.; Liu, J.; Xu, X.; Roy, R.; Donoghue, J. F.; Means, G. H.

2017-12-01

Coastal lakes sediments are valuable archives of paleo-hurricanes and environmental changes during the late Quaternary provided that they can be accurately dated. Here, we report new radiocarbon (14C) dates derived from various organic and inorganic substrates, including bulk sediment organic matter, plants, shells, particulate organic matter (POM) and dissolved organic matter (DOM), from three coastal lakes in Florida, and compare these ages to evaluate the "reservoir effect" on 14C dating of both organic and inorganic carbon in these lakes. Bulk sediment organic matter yielded consistently older 14C ages than contemporaneous plants and shell fragments, indicating significant radiocarbon deficiencies in sedimentary organic matter in these coastal lakes, caused by influx of old organic carbon from terrestrial sources (such as soils and ancient peat deposits) in the watershed. Several reversals are observed in the 14C ages of bulk sediment organic matter in sediment cores from these lakes, indicating that input of aged organic matter from terrestrial sources into these lakes can vary considerably over time. DOM and POM samples collected at different times also yielded variable 14C signatures, further confirming the temporal variability in the contribution of old organic carbon from terrestrial sources to the lakes. The 14C age discrepancy between bulk sediment organic matter and co-occurring plant fragments or shells varies from less than one hundred years to nearly three thousand years in sediment cores examined in this study. The results show that 14C ages obtained from bulk sediment organic matter in these coastal lakes are unreliable. Analyses of both modern and fossil shells from one of the lakes suggest that the 14C reservoir effect on inorganic carbon in the lake is small and thus freshwater shells (if preserved in the sediment cores) may serve as a good substrate for 14C dating in the absence of plant fragments. However, unidentifiable shell fragments, especially those associated with sand pockets (or sand layers), in coastal lake sediment cores are not suitable for 14C dating as they are likely of marine origin and affected by significant marine 14C reservoir effect.

The Impacts of Episodic Storm and Flood Events on Carbon and Sediment Delivery to Gulf of Mexico Sediments

NASA Astrophysics Data System (ADS)

Schreiner, K. M.; Carlin, J. A.; Sayers, L.; Swenson, J.

2017-12-01

Marine sediments are an important long-term reservoir for both recently fixed organic carbon (OC) and ancient rock derived OC, much of which is delivered by rivers. The ratio between these two sources of OC in turn regulates atmospheric levels of oxygen and carbon dioxide over geologic time, making this riverine delivery of OC, primarily carried by sediments, an important flux in the global carbon cycle. However, while the overall magnitude of these fluxes are relatively well known, it remains to be determined the importance of episodic events, like storms and floods, in the flux of OC from terrestrial to marine environments. Here, we present data from a 34 cm core collected from the Gulf of Mexico at a mid-shelf distal depocenter for the Brazos River in 2015, during a strong El Nino when that area of the country was experiencing 100-year flood events and anomalously high river flow. Based on analysis of the radioactive isotope 7Be, approximately the top 7-8 cm of the sediment in this core was deposited during this flood event. Both bulk elemental (C, N, and stable carbon isotopes) and chemical biomarker (lignin-phenol) data has been combined to provide information of the origin and chemistry of the OC in this core both before and during flooding. C:N and d13C indicate a mixture of marine-sourced and terrestrially-sourced OC throughout the length of the core with very little variation between the flood layer and deeper sediments. However, lignin-phenol concentrations are higher in flood-deposited sediment, indicating that this sediment is likely terrestrially-sourced. Lignin-phenol indicators of OC degradation state (Acid:Aldehyde ratios) indicate that flood sediment is fresher and less degraded than deeper sediments. Taken together, these results indicate that 1. Bulk analyses are not enough to determine OC source and the importance of flood events in OC cycling and 2. Episodic events like floods could have an oversized impact on OC storage in marine sediments.

The Characteristics of Turbidite Beds of Southwest Ryukyu Trench Floor: A new Approach From the X-ray Fluorescence Core Scanning Analysis

NASA Astrophysics Data System (ADS)

Hsiung, K. H.; Kanamatsu, T.; Ikehara, K.; Usami, K.; Saito, S.; Murayama, M.

2017-12-01

The southwest Ryukyu Trench near Taiwan is an ideal place for source-to-sink studies based on the distinctive sediment transport route between the terrestrial sediment source in Taiwan and the marine sink in the Ryukyu Trench. Using the bathymetric and seismic reflection data, we develop a sediment transport routes for understanding the ultimate sink of the southwest Ryukyu Trench floor. The southwest Ryukyu Trench floor can be regarded as the most distal depositional basin and isolated from the Ryukyu forearc basins. In addition, part of sediment from the proximal sources of the Ryukyu Islands and Yaeyama accretionary prism could be transported to the trench floor. We collected the piston core, PC04, from the southwest Ryukyu Trench floor of 6,147 m water depth in 3.23 m core length from cruise KR15-18, 2015. The coring site locates behind the natural levee of an obvious channel in the Ryukyu trench floor. The PC04 is composed of gray silty clay interbedded with numerous silt layers. Most of the silt layers are less than 2 cm in thickness. Based upon the core observation, X-ray fluorescence core scanning analysis and 14C age determinations, thirty-seven individual and thin beds were determined as turbidites. The results of X-ray fluorescence core scanning analysis provide continuous and high-resolution (1.0 mm of each point) assessment of relative change in the elemental ratios. Ca/Fe is a proxy for the terrigenous component of the sediment, indicating the High Ca and low Fe of each turbidite layers. Zr/Rb ratios of the marine sediments commonly used in the reflection of the original grain size variation. A large part of deep-sea turbidite beds are characterized by high Ca/Fe and Zr/Rb ratio values. These turbidite beds can be linked spatially over a distance of ˜200 km via submarine canyons within the Taiwan orogen. However, it is difficult to be linked temporally to certain events.

Sedimentation Deposition Patterns on the Chukchi Shelf Using Radionuclide Inventories

NASA Astrophysics Data System (ADS)

Cooper, L. W.; Grebmeier, J. M.

2016-02-01

Sediment core collections and assays of the anthropogenic and natural radioisotopes, 137Cs and 210Pb, respectively, are providing long-term indications of sedimentation and current flow processes on the Chukchi and East Siberian sea continental shelf. This work, which has been integrated into interdisciplinary studies of the Chukchi Sea supported by both the US Bureau of Ocean Energy Management (COMIDA Hanna Shoal Project) and the National Oceanic and Atmospheric Administration (Russian-US Long Term Census of the Arctic, RUSALCA) includes studies of total radiocesium inventories, sedimentation rate determinations, where practical, and depths of maxima in radionuclide deposition. Shallow maxima in the activities of the anthropogenic radionuclide in sediment cores reflect areas with higher current flow (Barrow Canyon and Herald Canyon; 3-6 cm) or low sedimentation (Hanna Shoal; 1-3 cm). The first sedimentation studies from Long Strait are consistent with quiescent current conditions and steady recent sedimentation of clay particles. Elsewhere, higher and more deeply buried radionuclide inventories (> 2 mBq cm-2 at 15-17 cm depth) in the sediments correspond to areas of high particle deposition north of Bering Strait where bioturbation in productive sediments is also clearly an important influence. Radiocesium activities from bomb fallout dating to 1964 are now present at low levels (<1 mBq cm-2) at the sediment surface, but burial of the bomb era radionuclide in sediments is observed to >20 cm. Independent sedimentation rate measurements with the natural radionuclide 210Pb are largely consistent with the radiocesium measurements.

Carotenoids in the Gulf of Gdansk sediments- useful markers of environmental conditions in the past

NASA Astrophysics Data System (ADS)

Krajewska, Magdalena; Szymczak-Żyła, Małgorzata; Kowalewska, Grażyna

2017-04-01

Carotenoids are a large group of natural compounds widespread in the aquatic environment. Most of carotenoids in sediments originate from phytoplankton, macroalgae, vascular plants and bacteria. Carotenoids undergo different reactions in water column and after deposition in sediments. Concentration and relative composition of pigments in sediments depend on such factors like primary production, phytoplankton taxonomy, sedimentation and accumulation rate, hydrological and post-depositional conditions. Because some pigments are unstable and can be degraded both by abiotic and biotic factors - in the presence of light, oxygen, herbivores or microorganisms activity, they provide information about conditions in water column and in sediments. They differ in stability and, due to that, carotenoids in marine sediments are indicators, not only of organic matter sources but also of pre- and post-depositional conditions. This work presents a concentration and distribution of selected carotenoids in recent (6 cores 0-20 cm) and deep (1 core, up to 400 cm) sediments of the Gulf of Gdansk- a highly eutrophic area of high primary production and high sedimentation rate. The sediments were collected during two cruises and analysed in framework of CLISED ('Climate Change Impact on Ecosystem Health- Marine Sediment Indicators') Polish- Norwegian research Project, grant no. 196128. Just after collection, the samples were frozen and kept in such a state until analysis in land laboratory. There, after extraction, carotenoids were analysed using high performance liquid chromatography (HPLC-DAD). Sediment age has been defined using C-14 dating. Sediments contained parent carotenoids, markers of the main phytoplankton groups occurring in the Baltic, e.g. diatoms, green algae and cyanobacteria. B-carotene in sediments is a better, averaged, marker of primary production than chlorophyll- a and similarly stable one as sum of chloropigments-a. Presentation will focus on cyanobacteria and their pigments record in sediments, because cyanobacterial blooms are good indicators of eutrophication and anaerobic conditions in the past. Carotenoids record in deep sediments was varied and there are periods of better or worse carotenoids preservation which proves climate changes.

Tracking the Transformation and Preservation of Organic Biomarkers in a Varved Sediment-Core Series

NASA Astrophysics Data System (ADS)

Tolu, J.; Bigler, C.; Bindler, R.

2014-12-01

An important premise for reconstructing environmental changes using sediment records is to understand which environmental information reaches the lake bottom and how diagenetic processes may affect the proxies, such as terrestrial and aquatic organic biomarkers. We can tackle this question using a unique series of varved sediment cores collected from the lake Nylandssjön (northern Sweden). In addition to limnological and sediment trap sampling since 2001, we have a collection of freeze cores taken in late winter and stored since 1979, which allows us to track individual varve years (e.g., 1978) over time (~30 years). A previous study using this collection showed that 23 % of C and 35 % of N were lost during the first 25 years with a C:N ratio increase of ≈21, suggesting important implications for diagenetic effects on organic biomarkers. To assess the preservation/transformation of organic biomarkers, we developed a new Pyrolysis-Gas Chromatography/Mass Spectrometry method that allows the rapid determination of biomarkers from the common OM classes (e.g., plant waxes, microbial lipids, lignins) using sub-mg sample sizes and thus applicable to high-resolution sampling of the varved sediment (Tolu et al., under review). Our results show that the different biomarkers exhibit a broad spectrum of reactivities over ~30 years -% change determined by ([Peak area at t] - [Peak area at t=0])/ [peak area at t=0] x 100-. For example: 67-80 % of the algal chlorophyll-derived product 'phytene' is lost depending which single varve year is followed over time (e.g., 1979). Only 12-32 % of "pristene", the degraded form of algal chlorophyll, is lost. The guaiacyl and syringyl lignin units are affected by a smaller loss, i.e. 5-15 %, and the S/G ratio, indicative of angiosperm/gymnosperm plant input remains stable, which is contrary to previous work on non-varved lake sediments. Considering all biomarkers, the degradation/production plateaued after ~15 years, which indicates that reconstructions of changes in OM quality sedimentation can be safely done from the 15th varve without further significant changes induced by diagenesis. To reconstruct changes in OM quality within the recent 15 years, the stable biomarkers and the degradation rates of the non-stable ones have to be used. 1 Gälman et al. (2008) Limnol Oceanogr 53: 1076

The GIK-Archive of sediment core radiographs with documentation

NASA Astrophysics Data System (ADS)

Grobe, Hannes; Winn, Kyaw; Werner, Friedrich; Driemel, Amelie; Schumacher, Stefanie; Sieger, Rainer

2017-12-01

The GIK-Archive of radiographs is a collection of X-ray negative and photographic images of sediment cores based on exposures taken since the early 1960s. During four decades of marine geological work at the University of Kiel, Germany, several thousand hours of sampling, careful preparation and X-raying were spent on producing a unique archive of sediment radiographs from several parts of the World Ocean. The archive consists of more than 18 500 exposures on chemical film that were digitized, geo-referenced, supplemented with metadata and archived in the data library PANGAEA®. With this publication, the images have become available open-access for use by the scientific community at https://doi.org/10.1594/PANGAEA.854841.

Spatial and temporal distributions of polycyclic aromatic hydrocarbons in sediments from the Songhua River, China

NASA Astrophysics Data System (ADS)

Dong, D.; Guo, Z.; Liu, X.; Hua, X.; Liang, D.

2013-12-01

Polycyclic aromatic hydrocarbons (PAHs), a class of typical persistent organic pollutants, widely exist in the environment and are potentially harmful to human health. They can enter the waters through atmospheric deposition, soil leaching, shipping, sewage discharges and surface runoff. In recent years, many studies on the distributions of PAHs in major rivers, lakes and bays around the world have been carried out. In this study, 9 surface sediments (0-10cm) were sampled from the Songhua River in Jilin and Heilongjiang provinces. The contents of 16 PAHs in the US Environmental Protection Agency list of priority pollutants were determined and their spatial distributions were discussed. Sediment cores (50cm length) in three oxbow lakes in this area were also collected and cut into 2 cm thickness sub-samples. PAHs concentrations in these samples were determined and the cores were dated using a 210Pb geochronology technique. Finally, the sedimentary history of PAHs in the Songhua River since the 1920s was revealed. Results indicated that total concentration of the 16 PAHs analyzed in the surface sediments was 187-2079 ng/g (dry weight), and the mean was 1029 ng/g. Sediments collected from near urban areas (Jilin and Harbin City) contained higher PAHs content. Compared with the domestic and international rivers, the PAHs content in this river sediments is at a medium level. The PAHs profiles showed that 2-3 ring PAHs, especially naphthalene, were dominant in all of the samples. Sedimentary flux can reflect the accumulating history of pollutants better. The PAHs fluxes were low and varied little from the 1920s to 1970s, but higher PAH fluxes were found since the 1980s in each core (Fig. 1). The PAHs sedimentary flux near Harbin City (Shuangcheng) was found changed remarkably. We inferred that the PAHs might be influenced by hydrological conditions, population mobility and economic activity in this area. PAHs sedimentary record in the Songhua River revealed that the economic development in large cities in this area lagged behind the environmental protection. Acknowledgments: This work was supported by Specialized Research Fund for the Doctoral Program of Higher Education (No. 20100061110041), and the Major Science and Technology Program for Water Pollution Control and Treatment, China (No. 2009ZX0707-001-03). Fig. 1 PAHs fluxes vs. year in sediment cores from Songyuan, Shuangcheng (Harbin) and Mulan

Laboratory investigation of the erosion of cohesive sediments under oscillatory flows using a synchronized imaging technique

NASA Astrophysics Data System (ADS)

Sou, I.; Calantoni, J.; Reed, A. H.; Furukawa, Y.

2012-12-01

A synchronized dual stereo particle image velocimetry (PIV) measurement technique is used to examine the erosion process of a cohesive sediment core in the Small Oscillatory Flow Tunnel (S-OFT) in the Sediment Dynamics Laboratory at the Naval Research Laboratory, Stennis Space Center, MS. The PIV system uses four cameras and a dual cavity Nd:YAG laser. The system allows for a pair of stereo PIV windows of about 10 cm by 10 cm each to be arbitrarily located within a single light sheet. Image pairs were acquired with all four cameras at 50 Hz for 50 consecutive seconds for each flow condition. The stereo PIV windows were positioned on either side of sediment cores inserted along the centerline of the S-OFT allowing for a total measurement window of about 20 cm long by 10 cm high with sub-millimeter spacing on resolved velocity vectors. The oscillatory flows are generated by two types of driving mechanism (scotch yoke and crank lever) for converting the rotational motion of the flywheel into the linear motion of a piston. The period of oscillation ranged from 2.86 to 6.12 seconds with constant semi-excursion amplitude in the test section of 9 cm. Two kinds of inorganic sediment samples were examined. One was a mixture of 50% kaolinite and 50% 500-micron sand under flows driven by the crank lever mechanism. Another sediment core was a mixture of 50% mud collected in Galveston Bay, TX, and 50% 250-micron sand under flows driven by the scotch-yoke mechanism. During the erosion process, Kelvin-Helmholtz instabilities were observed as the flow accelerated in each direction and eventually were broken down when the flow reversed. An example of the instantaneous velocity field superimposed on the raw image is shown in Figure 1. The relative concentration of suspended sediments under different flow conditions was estimated using the intensity of light scattered from the sediment particles in suspension. By subtracting the initial light scattered from the mud core, the residual light intensity was assumed to be scattered from suspended sediments eroded from the core. Relative comparisons were only made using the same sample mixture since it is difficult, if not impossible, to calibrate the light scattering from different sediments.; Figure 1. An example of the instantaneous time-resolved velocity field superimposed on the raw image.

Regional environmental change and human activity over the past hundred years recorded in the sedimentary record of Lake Qinghai, China.

PubMed

Sha, ZhanJiang; Wang, Qiugui; Wang, Jinlong; Du, Jinzhou; Hu, Jufang; Ma, Yujun; Kong, Fancui; Wang, Zhuan

2017-04-01

Environmental change and human activity can be recorded in sediment cores in aquatic systems such as lakes. Information from such records may be useful for environmental governance in the future. Six sediment cores were collected from Lake Qinghai, China and its sublakes during 2012 and 2013. Measurements of sediment grain-size fractions indicate that sedimentation in the north and southwest of Lake Qinghai is dominated by river input, whereas that in Lake Gahai and Lake Erhai is dominated by dunes. The sedimentation rates in Lake Qinghai were calculated to be 0.101-0.159 cm/y, similar to the rates in other lakes on the Qinghai-Tibetan Plateau. Using these data and sedimentation rates from the literature, we compiled the spatial distribution of sedimentation rates. Higher values were obtained in the three main areas of Lake Qinghai: two in river estuaries and one close to sand dunes. Lower values were measured in the center and south of the lake. Measurements of total organic carbon (TOC), total nitrogen (TN), phosphorus concentrations, and TOC/TN ratios in three cores (QH01, QH02, and Z04) revealed four horizons corresponding to times of increased human activity. These anthropogenic events were (1) the development of large areas of cropland in the Lake Qinghai watershed in 1960, (2) the beginning of nationwide fertilizer use and increases in cropland area in the lake watershed after 1970, (3) the implementation of the national program "Grain to Green," and (4) the rapid increase in the tourism industry from 2000. Profiles of Rb, Sr concentrations, the Rb/Sr ratio, and grain-size fraction in core Z04 indicate that the climate has become drier over the past 100 years. Therefore, we suggest that lake sediments such as those in Lake Qinghai are useful media for high-resolution studies of regional environmental change and human activity.

Anthropogenic and natural variability in the composition of sedimentary organic matter of the urbanised coastal zone of Montevideo (Río de la Plata).

PubMed

Bueno, C; Brugnoli, E; Bergamino, L; Muniz, P; García-Rodríguez, F; Figueira, R

2018-01-01

This study is aimed to identify the different sources of sedimentary organic matter (SOM) within Montevideo coastal zone (MCZ). To this end δ 13 C, δ 15 N and C/N ratio were analysed in surface sediments and a sediment core. Sediment core analysis showed that until ~1950CE SOM was mainly marine, observing a shift towards lower δ 13 C in recent sediments, evidencing an estuarine composition. This trend was associated to the climatic variability, which exerted a major influence on the SOM composition, leading to an increased input of terrigenous material and associated anthropogenic contaminants. Surface sediments collected during different El Niño South Oscillation (ENSO) phases did not show inter-annual variability in SOM composition, which was mainly marine in both eastern and western region of MCZ and estuarine in Montevideo Bay. This spatial pattern provides new insights on the dynamics and factors affecting organic matter sources available for primary consumers along the study region. Copyright © 2017 Elsevier Ltd. All rights reserved.

Rock magnetic and geochemical analyses of surface sediment characteristics in deep ocean environments: A case study across the Ryukyu Trench

NASA Astrophysics Data System (ADS)

Kawamura, N.; Kawamura, K.; Ishikawa, N.

2008-03-01

Magnetic minerals in marine sediments are often dissolved or formed with burial depth, thereby masking the primary natural remanent magnetization and paleoclimate signals. In order to clarify the present sedimentary environment and the progressive changes with burial depth in the magnetic properties, we studied seven cores collected from the Ryukyu Trench, southwest Japan. Magnetic properties, organic geochemistry, and interstitial water chemistry of seven cores are described. Bottom water conditions at the landward slope, trench floor, and seaward slope are relatively suboxic, anoxic, and oxic, respectively. The grain size of the sediments become gradually finer with the distance from Okinawa Island and finer with increasing water depth. The magnetic carriers in the sediments are predominantly magnetite and maghemized magnetite, with minor amounts of hematite. In the topmost sediments from the landward slope, magnetic minerals are diluted by terrigenous materials and microfossils. The downcore variations in magnetic properties and geochemical data provided evidence for the dissolution of fine-grained magnetite with burial depth under an anoxic condition.

Diagenetic effects on magnetic minerals in a Holocene lacustrine sediment core from Huguangyan maar lake, southeast China

NASA Astrophysics Data System (ADS)

Wu, Xudong; Wang, Yong; Bian, Liu; Shen, Ji

2016-09-01

Post-depositional reductive diagenesis usually results in partial or entire cleansing of the pristine palaeomagnetic signal, therefore, its intensity is important to be assessed for sediments that are in the purpose of retrieving palaeomagnetic information. Grain size, rock magnetic and geochemical studies on the entire core, along with scanning electron microscope observations and X-ray diffraction analyses for representative samples were carried out on a Holocene sediment core retrieved from the deep water part of Huguangyan maar lake (HGY), southeast China. The pristine magnetic mineral assemblage of the studied core is domianted by superparamagnetic (SP) and stable single domain titanomagnetite, and high coercivity minerals are not detectable. Based on down-core variations of the average grain size (MZ), total organic carbon (TOC), detrital elements (Al, Ti, Fe and Mn) and the concentration and mineralogy of magnetic minerals, the studied core could be divided into three subsections. The uppermost subsection is the least affected by diagenesis, with detrital titanomagnetite as the dominant magnetic mineral. This is owing to low TOC contents, but high detrital input generated by weak Asian summer monsoon intensity during the late Holocene. The intermediate subsection shows down-core progressively enhanced dissolution of detrital titanomagnetite, and concomitant formation of authigenic pyrite and siderite, which indicates down-core progressively enhanced diagenesis generated by down-core progressive increasing TOC content, but decreasing detrital input as the result of down-core progressively strengthened Asian summer monsoon intensity. The pristine magnetic mineral assemblage has been profoundly modified in the lowermost subsection. At certain positions of the lowermost subsection, detrital titanomagnetite has been even completely dissolved via diagenesis, giving place to authigenic pyrite and siderite. High TOC content, but low detrital input generated from strong Asian summer monsoon intensity during the early Holocene are accountable for intensive diagenesis in the lowermost subsection. Complete erasing of detrital magnetic input signal at certain positions of the lowermost subsection, and considerable formation of authigenic siderite indicate that palaeomagnetic records of the studied core have been significantly compromised. The studied core has relatively higher TOC content, lower detrital matter content, calmer sedimentary environments, and less DO available at its water-sediment interface than the cores retrieved at relatively shallower water depths, which all contribute to its relatively stronger diagenesis. Progressive thickening of the upper two subsections with increasing water depth is owing to progressive increase in sedimentation rate with increasing water depth, which is the key factor in determining the thickness of each diagenetic subsection of cores from HGY. It would be better that lake sediments for palaeomagnetic investigations collected at a water depth shallower than the depth of its thermocline.

Distribution and sources of polychlorinated biphenyls in Woods Inlet, Lake Worth, Fort Worth, Texas, 2003

USGS Publications Warehouse

Besse, Richard E.; Van Metre, Peter C.; Wilson, Jennifer T.

2005-01-01

Woods Inlet is a flooded stream channel on the southern shore of Lake Worth along the western boundary of Air Force Plant 4 in Fort Worth, Texas, where elevated polychlorinated biphenyl (PCB) concentrations in sediment were detected in a previous study. In response, the U.S. Geological Survey, in cooperation with the U.S. Air Force, conducted a study in 2003 to map the extent of elevated PCB concentrations in Woods Inlet and to identify possible sources (or more specifically, source areas) of PCBs in the watershed of Woods Inlet. Three gravity cores (penetration to pre-reservoir sediment at three sites) and 17 box cores (surficial bottom sediment samples) were collected in Woods Inlet. Suspended sediment in stormwater runoff and streambed sediment were sampled in tributaries to Woods Inlet following storms. Assemblages of PCB congeners in surficial inlet sediments and suspended and streambed sediments were analyzed to indicate sources of PCBs in the inlet sediments on the basis of chemical signatures of PCBs. Woods Inlet receives runoff primarily from three tributaries: (1) Gruggs Park Creek, (2) the small unnamed creek that drains a Texas National Guard maintenance facility, called TNG Creek for this report, and (3) Meandering Road Creek. Twenty-seven of 209 possible PCB congeners were analyzed. The sum of the congeners was used as a measure of total PCB. The spatial distribution of total PCB concentrations in the inlet indicates that most PCBs are originating in the Meandering Road Creek watershed. Peak total PCB concentrations in the three gravity cores occurred at depths corresponding to sediment deposition dates of about 1960 for two of the cores and about 1980 for the third core. The magnitudes of peak total PCB concentrations in the gravity cores followed a spatial distribution generally similar to that of surficial bottom sediment concentrations. Total PCB concentrations in suspended and streambed sediment varied greatly between sites and indicated a likely source of PCBs associated with a sampling site that receives runoff from Air Force Plant 4. Three approaches to the analyses of congener assemblages indicate that PCBs in surficial bottom sediment of Woods Inlet primarily enter Lake Worth from Meandering Road Creek and that runoff from Air Force Plant 4 is a source of the PCBs in Meandering Road Creek. Although current (2003) transport of PCBs from Air Force Plant 4 to the creek is occurring, large decreases in PCB concentrations with decreasing age in two cores indicate that PCB loading to the inlet has decreased greatly since the 1960s. Because runoff entering Meandering Road Creek from some parts of Air Force Plant 4 was not measured or sampled in this study, it cannot be said with certainty that the Air Force Plant 4 site sampled is the only source of PCBs to Meandering Road Creek.

Historical record of mercury contamination in sediments from the Babeni Reservoir in the Olt River, Romania.

PubMed

Bravo, Andrea Garcia; Loizeau, Jean-Luc; Ancey, Lydie; Ungureanu, Viorel Gheorghe; Dominik, Janusz

2009-08-01

Mercury (Hg) is a ubiquitous and hazardous contaminant in the aquatic environment showing a strong biomagnification effect along the food chain. The most common transfer path of Hg to humans is contaminated fish consumption. In severely exposed humans, Hg poisoning may lead to damage in the central nervous system. Thus, it is important to examine current and past contamination levels of Hg in aquatic milieu. The Olt River is the largest Romanian tributary of the Danube River. The use of Hg as an electrode in a chlor-alkali plant contributed to the contamination of the aquatic environment in the Rm Valcea region. The purpose of this study was to compare the current state of Hg contamination with the past contamination using a historical record obtained from a dated sediment core from one of the Olt River reservoirs (Babeni) located downstream from the chlor-alkali plant. To our knowledge, no published data on Hg contamination in this region are available. The Babeni Reservoir was selected for this study because it is situated downstream from the chlor-alkali plant, whilst the other reservoirs only retain the pollutants coming from the upstream part of the watershed. Preliminary analyses (unpublished) showed high Hg concentrations in the surface sediment of the Babeni Reservoir. One core was taken in the upstream Valcea Reservoir to provide a local background level of Hg concentrations in sediments. Sediment texture was uniform in the cores from both reservoirs. Laminated sediment structure, without any obvious discontinuities, was observed. Hg concentrations in the sediment core from the Valcea Reservoir were low and constant (0.01-0.08 mg/kg). In Babeni Reservoir sediments, Hg concentrations were very high in the deeper core section (up to 45 mg/kg in the longest core) and decreased to lower concentrations toward the top of the cores (1.3-2.4 mg/kg). This decrease probably reflects technological progress in control of emissions from the Hg-cell-based chlor-alkali industry. Two strong peaks could be distinguished in older sediments. The mean rate of sedimentation (5.9 cm/year) was calculated from the depth of the (137)Cs Chernobyl peak. This was in good agreement with the sedimentation rate estimated at this site from a bathymetric study. Assuming a constant sedimentation rate, the two Hg peaks would reflect two contamination events in 1987 and 1991, respectively. However, it is also possible that the two peaks belong to the same contamination event in 1987 but were separated by a sediment layer richer in sand and silt. This layer had a low Hg concentration, which can be interpreted as a mass deposition event related to a major flood bringing Hg-free sediments. Whilst the chlor-alkali plant partly switched to a cleaner technology in 1999, no obvious decrease of Hg concentrations was observed in recent decade. Results from the sediment core reflected the historical trend of Hg release from the chlor-alkali plant, revealed important contamination episodes and confirmed a legacy of contamination of Hg in recent sediments even if the concentrations of Hg decreased toward the surface due to a more efficient emission control. Although the Hg concentrations in Babeni Reservoir sediments were extremely high in the late eighties and they remain one order of magnitude higher in the surface sediments than in sediments from the upstream reservoir, little is known about the transfer of Hg to the biota and human population. Our initial measurements indicate the presence of monomethyl-Hg (MMHg) in pore water, but further studies are necessary to evaluate fluxes of MMHg at the sediment-water interface. Samples of fish and hair from various groups of the local population were recently collected to evaluate the potential hazard of Hg contamination to human health in the Rm Valcea region.

Shipboard magnetic field "noise" reveals shallow heavy mineral sediment concentrations in Chesapeake Bay

USGS Publications Warehouse

Shah, Anjana K.; Vogt, Peter R.; Rosenbaum, Joseph G.; Newell, Wayne L.; Cronin, Thomas M.; Willard, Debra A.; Hagen, Rick A.; Brozena, John; Hofstra, Albert

2012-01-01

Shipboard magnetic field data collected over Chesapeake Bay exhibit low-amplitude, short-wavelength anomalies that most likely indicate shallow concentrations of heavy mineral sediments. Piston core layers and black sand beach samples exhibit enhanced magnetic susceptibilities and carry remanent magnetization, with mineralogical analyses indicating ilmenite and trace magnetite and/or maghemite and hematite. The anomalies are subtle and would be filtered as noise using traditional approaches, but can instead be highlighted using spectral methods, thus providing nearly continuous coverage along survey tracks. The distribution of the anomalies provides constraints on relevant sorting mechanisms. Comparisons to sonar data and previous grab samples show that two of three areas surveyed exhibit short-wavelength anomalies that are clustered over sand-covered areas, suggesting initial sorting through settling mechanisms. This is supported by a correlation between core magnetic susceptibility and grain size. Near the Choptank River, where sediment resuspension is wave-dominated, anomalies show a sharp decrease with seafloor depth that cannot be explained by signal attenuation alone. In Pocomoke Sound, where both tidal currents and wave-action impact sediment resuspension, anomalies show a more gradual decrease with depth. Near the mouth of the bay, where there is a higher influx of sediments from the continental shelf, short-wavelength anomalies are isolated and do not appear to represent heavy mineral sand concentrations. These combined observations suggest the importance of further sorting by erosional processes in certain parts of the bay. Additionally, comparisons of these data to cores sampling pre-Holocene sediments suggest that the sorting of heavy minerals in higher energy, shallow water environments provides a mechanism for correlations between core magnetic susceptibility and sea-level changes.

Origins of sediment-associated contaminants to the Marais Vernier, the Seine Estuary, France

USGS Publications Warehouse

Van Metre, P.C.; Mesnage, V.; Laignel, B.; Motelay, A.; Deloffre, J.

2008-01-01

The Marais Vernier is the largest freshwater wetland in the Seine Estuary in northern France. It is in a heavily urbanized and industrialized region and could be affected by atmospheric deposition and by fluvial input of contaminants in water diverted from the Seine River. To evaluate contaminant histories in the wetland and the region, sediment cores were collected from two open-water ponds in the Marais Vernier: the Grand-Mare, which was connected to the Seine by a canal from 1950 to 1996, and the Petite Mare, which has a small rural watershed. Diversions from the Seine to the Grand-Mare increased sedimentation rates but mostly resulted in low contaminant concentrations and loading rates, indicating that the sediment from the Seine was predominantly brought upstream by tidal currents from the estuary and was not from the watershed. Atmospheric sources of metals dominate inputs to the Petite Mare; however, runoff of metals from vehicle-related sources in the watershed might contribute to the upward trends in concentrations of Cr, Cu, and Zn. Estimates of atmospheric deposition using the Petite Mare core are consistent with measured deposition in the region and are mixed (similar for Hg and Pb; larger for Cd, Cu, and Zn) compared with deposition estimated from sediment cores in the northeastern United States. A local source of PAHs in the watershed of the Petite Mare is indicated by higher concentrations, higher accumulation rates, and a different, more petrogenic, PAH assemblage than in the Grand-Mare. The study illustrates how diverse sources and transport pathways can affect wetlands in industrial regions and can be evaluated using sediment cores from the wetland ponds. ?? 2008 Springer Science+Business Media B.V.

Chronostratigraphy of a salt marsh sediment core from North Cinder Island in the Town of Hempstead, Long Island, NY, using radiocarbon and pollen

NASA Astrophysics Data System (ADS)

Farmer, E. C.; Browne, J.; Peteet, D. M.; Cochran, K. K.; Heilbrun, C.; Chery, N.; LongJohn, T.; Mayo, J.; Ricigliano, V.

2016-12-01

A 122 cm long sediment core was collected from the salt marsh of North Cinder Island (73.6092W, 40.6097N), a small uninhabited island in Middle Bay between Oceanside and Point Lookout, in the Town of Hempstead, NY, on 2 July 2013, in order to investigate the age of the marsh and the history of trace metal pollution in the area. First, to determine the chronostratigraphy of the core, pollen counts were compared to radiocarbon measurements. Sediment samples at several depths in the core were analyzed for Pine, Oak, Hickory, Birch, Grass (S. alterniflora and S. patens), and Ragweed pollen. The concentration of Ragweed was below 3% in samples below 80cm, and greater than 7% in samples above 80cm. This proliferation of a disturbance species suggests that layers deeper than 81cm were deposited prior to widespread European settlement, sometime in the 1600s AD. Paired radiocarbon measurements on sieved fine sediment at 42-43 cm depth, however, match well with each other (their 1-sigma confidence intervals overlap), but suggest a calendar age between 932 and 997 years before present. Paired radiocarbon measurements from the 60-61 cm depth also match well with each other, but represent an age that is approximately 200 years younger. Additional paired radiocarbon measurements at 78-79 cm and 96-97 cm depths give older ages, as expected stratigraphically. Perhaps the reversal between 43 and 60 cm represents reworking of sediments in the marsh by tidal currents. Interestingly, root matter extracted from the sediment at the same depths gives radiocarbon ages that range from 600-1200 years younger. Perhaps the roots penetrate down through older sediment, or perhaps the fine sediment is comprised of recaptured sediment with lignin or other residual organic matter that is older because it is difficult to break down. This would explain the apparent contradiction between the radiocarbon dates on fine sediment and the younger pollen date at a deeper depth.

Late Holocene Environmental History of the Los Osos Watershed, Morro Bay, CA

NASA Astrophysics Data System (ADS)

Broadman, E.; Reidy, L. M.; Wahl, D.

2014-12-01

A comprehensive understanding of past changes in wetland ecosystems is integral for creating policies for modern land use practices. The Morro Bay salt marsh is home to a large wetland that has experienced significant environmental impacts in the last few centuries. In this study, sediment cores from the Morro Bay salt marsh were analyzed to discern changes in environment since the time of European contact, which occurred in 1772. The marsh is fed by two creeks (Chorro and Los Osos) and their associated watersheds. Sediment cores taken from a portion of the marsh fed by Los Osos creek were analyzed and the results compared to those from previous studies on cores taken from the Chorro and Los Osos portions of the marsh. Magnetic susceptibility, loss on ignition, pollen, radiocarbon, and X-ray fluorescence (XRF) analyses were conducted. An age-depth model was established for the Los Osos cores using two radiocarbon dates, as well as Erodium cicutarium as a chronological marker. Preliminary pollen analysis from Chorro marsh cores indicates vegetation shifts at the time of contact, when the salt marsh formed. Magnetic susceptibility and XRF data indicate dramatically increased rates of erosion from the time of contact consistently until the present. Influx of non-carbonate inorganic material also indicates a rapid increase in sedimentation in the marsh starting at the time of contact. Comparison of sedimentation rates between the two creeks suggests that differences in watershed geomorphology and land use practices have had pronounced impacts on erosional processes. Over the last decade, the Morro Bay National Estuary Program (MBNEP) has taken more measures to reduce erosion and sedimentation rates in the Chorro watershed, as is reflected by reduced sedimentation rates in MBNEP data collected within the last few years. Our study helps to elucidate the impacts of anthropogenic land use change on wetland systems, and provides much needed data to policy makers seeking to understand and attenuate anthropogenic impacts on sensitive coastal ecosystems.

Sources and fate of sediment organic matter in Asia's largest brackish water lagoon and nearby mangrove ecosystem

NASA Astrophysics Data System (ADS)

Mukherjee, R.; Muduli, P. R.; Barik, S.; Kumar, S.

2017-12-01

Coastal lagoons and mangrove ecosystems regularly undergo natural (tidal) and anthropogenic (riverine inputs) forcings. After effects of these forcings cause coastal environments to sustain high biological production leading to high suspended organic matter (OM) and hence fast sedimentation and accumulation of OM in sediments.The different sources of OM and its burial in tropical lacustrine and mangrove systems have been rarely studied in detail with a few reports from Indian estuaries. The present study attempts to understand the sources and fate organic matter at two Ramsar sites, viz. Chilika Lake (Asia's largest brackish water lagoon) and nearby Bhitarkanika mangroves, located in the east coast of India. We measured nitrogen and carbon content (% N and % C) and isotopic composition (δ13Corg and δ15N) of OM at different depths in eight and three sediment cores collected from the Chilika lagoon and Bhitarkanika mangroves, respectively. Overall, the mean δ13Corg and % C in the lagoon were ‒21.10 ± 0.79 ‰ and 0.84 ± 0.47 %, respectively; whereas the same for mangrove cores were ‒24.56 ± 0.80 ‰ and 1.04 ± 0.26 %, respectively. Similarly, average δ15N and % N in the lagoon cores were 4.15 ± 0.63 ‰ and 0.11 ± 0.05 %, respectively; for mangrove cores the values were 4.28 ± 0.50 ‰ and 0.07 ± 0.01 %, respectively. Preliminary analysis of the isotopic composition (δ13Corg and δ15N) and elemental ratios indicates that organic carbon in the sediment at Bhitarkanika mangrove was of terrigenous, marine and in situ origin, whereas cores of Chilika lagoon showed predominantly marine signature. No relationship between δ13Corg of suspended and sediment in the Chilika lagoon indicates these two organic pools to be not directly coupled. End member mixing model in the mangrove ecosystem indicate on an average 50 % terrestrial contribution to the OM pool.

Geological controls on the occurrence of gas hydrate from core, downhole log, and seismic data in the Shenhu area, South China Sea

USGS Publications Warehouse

Xiujuan Wang,; ,; Collett, Timothy S.; Lee, Myung W.; Yang, Shengxiong; Guo, Yiqun; Wu, Shiguo

2014-01-01

Multi-channel seismic reflection data, well logs, and recovered sediment cores have been used in this study to characterize the geologic controls on the occurrence of gas hydrate in the Shenhu area of the South China Sea. The concept of the "gas hydrate petroleum system" has allowed for the systematic analysis of the impact of gas source, geologic controls on gas migration, and the role of the host sediment in the formation and stability of gas hydrates as encountered during the 2007 Guangzhou Marine Geological Survey Gas Hydrate Expedition (GMGS-1) in the Shenhu area. Analysis of seismic and bathymetric data identified seventeen sub-linear, near-parallel submarine canyons in this area. These canyons, formed in the Miocene, migrated in a northeasterly direction, and resulted in the burial and abandonment of canyons partially filled by coarse-grained sediments. Downhole wireline log (DWL) data were acquired from eight drill sites and sediment coring was conducted at five of these sites, which revealed the presence of suitable reservoirs for the occurrence of concentrated gas hydrate accumulations. Gas hydrate-bearing sediment layers were identified from well log and core data at three sites mainly within silt and silt clay sediments. Gas hydrate was also discovered in a sand reservoir at one site as inferred from the analysis of the DWL data. Seismic anomalies attributed to the presence of gas below the base of gas hydrate stability zone, provided direct evidence for the migration of gas into the overlying gas hydrate-bearing sedimentary sections. Geochemical analyses of gas samples collected from cores confirmed that the occurrence of gas hydrate in the Shenhu area is controlled by the presence thermogenic methane gas that has migrated into the gas hydrate stability zone from a more deeply buried source.

Erosion Characteristics and Horizontal Variability for Small Erosion Depths in the Sacramento - San Joaquin River Delta, California, USA

NASA Astrophysics Data System (ADS)

Schoellhamer, D. H.; Manning, A. J.; Work, P. A.

2015-12-01

Cohesive sediment in the Sacramento-San Joaquin River Delta affects pelagic fish habitat, contaminant transport, and marsh accretion. Observations of suspended-sediment concentration in the delta indicate that about 0.05 to 0.20 kg/m2 are eroded from the bed during a tidal cycle. If erosion is horizontally uniform, the erosion depth is about 30 to 150 microns, the typical range in diameter of suspended flocs. Application of an erosion microcosm produces similarly small erosion depths. In addition, core erodibility in the microcosm calculated with a horizontally homogeneous model increases with depth, contrary to expectations for a consolidating bed, possibly because the eroding surface area increases as applied shear stress increases. Thus, field observations and microcosm experiments, combined with visual observation of horizontally varying biota and texture at the surface of sediment cores, indicate that a conceptual model of erosion that includes horizontally varying properties may be more appropriate than assuming horizontally homogeneous erosive properties. To test this hypothesis, we collected five cores and measured the horizontal variability of shear strength within each core in the top 5.08 cm with a shear vane. Small tubes built by a freshwater worm and macroalgae were observed on the surface of all cores. The shear vane was inserted into the sediment until the top of the vane was at the top of the sediment, torque was applied to the vane until the sediment failed and the vane rotated, and the corresponding dial reading in Nm was recorded. The dial reading was assumed to be proportional to the surface strength. The horizontal standard deviation of the critical shear stress was about 30% of the mean. Results of the shear vane test provide empirical evidence that surface strength of the bed varies horizontally. A numerical simulation of erosion with an areally heterogeneous bed reproduced erosion characteristics observed in the microcosm.

Sediment characteristics and configuration within three dam impoundments on the Kalamazoo River, Michigan, 2000

USGS Publications Warehouse

Rheaume, S.J.; Rachol, C.M.; Hubbell, D.L.; Simard, Andreanne

2002-01-01

The removal of the remnants of three hydroelectric dams on the Kalamazoo River near Plainwell, Otsego, and Allegan, Michigan, has been proposed. The benefits of this removal include returning the Kalamazoo River to its pre-dam flow, increasing recreational use and safety on the river, and improving aquatic habitat. The U.S. Environmental Protection Agency has designated this reach of the Kalamazoo River as a Federal Superfund site because of the historical discharge of papermill waste containing polychlorinated biphenyls. Much of this waste material remains concentrated in organic sediment and kaolinite clay deposited upstream from the three dam foundations. Sediment containing up to 150 milligrams per kilogram polychlorinated biphenyls could move if dam foundations are removed; therefore, it is necessary to estimate the characteristic and configuration of the sediment before work begins. Data collected from augered sections and sediment cores show that impoundment sediments were deposited in two distinctly different sedimentary environments. Interbedded lacustrine sediments that overlie the pre-dam channel surface consist of organic-rich silt and clay, fine to medium sand, and some gravel. These materials were deposited in a repetitive, cyclic fashion related to former stream velocities when the impoundment water levels were 5-10 feet higher. Lowering of these water levels and demolition of the superstructures of these dams resulted in erosion of much of these instream lacustrine sediments and subsequent deposition of coarse-grained alluvium in the impounded channel behind the remaining dam foundations. The composite thicknesses of the lacustrine deposits and overlying alluvium was determined from sediment cores collected from each impoundment. The volume of instream sediment contained in each impoundment is estimated to be about 77,600 cubic yards at the Plainwell impoundment; 268,900 cubic yards at the Otsego impoundment; and 1,192,600 cubic yards at the Trowbridge impoundment. Estimates do not include bank or flood-plain deposits.

The Legacy of Arsenic Contamination from Giant Mine, Northern Canada: An Assessment of Impacts Based on Lake Water and Lake Sediment Core Analysis

NASA Astrophysics Data System (ADS)

Blais, J. M.; Korosi, J.

2016-12-01

The Giant Mine, which operated between 1948 and 2004 and located near the City of Yellowknife (Northwest Territories, Canada), has left a legacy of arsenic, antimony, and mercury contamination extending to the present day. Over 20,000 tonnes of arsenic trioxide dust was released from roaster stack emissions during its first 10 years of operations, leading to a significant contamination of the surrounding landscape. Here we present a summary of impacts by the recent contamination from Giant Mine on the surrounding region. A survey we conducted of 25 lakes of the region in 2010 revealed that most lake water within a 15 km radius of the roaster stack had arsenic concentrations in water > 10 mg/L, the standard for drinking water, with concentrations declining exponentially with increasing distance from the roaster stack. Sediment cores from lakes were collected near the Giant Mine roaster stack and radiometrically dated by 137Cs and excess 210Pb. Arsenic concentrations in these sediments increased by 1700% during the 1950s and 60s, consistent with the history of arsenic releases from roaster emissions. Correspondingly, pelagic diatoms and cladocerans were extirpated from one lake during this period, based on microfossil analysis of lake sediment deposits. Sediment core analysis further showed that this lake ecosystem has not recovered, even ten years after closure of the mine. Likely causes for the lack of recent recovery are explored with the use of sediment toxicity bioassays, using a novel paleo-ecotoxicological approach of using toxicity assessments of radiometrically dated lake sediment horizons.

A three-dimensional stratigraphic model for aggrading submarine channels based on laboratory experiments, numerical modeling, and sediment cores

NASA Astrophysics Data System (ADS)

Limaye, A. B.; Komatsu, Y.; Suzuki, K.; Paola, C.

2017-12-01

Turbidity currents deliver clastic sediment from continental margins to the deep ocean, and are the main driver of landscape and stratigraphic evolution in many low-relief, submarine environments. The sedimentary architecture of turbidites—including the spatial organization of coarse and fine sediments—is closely related to the aggradation, scour, and lateral shifting of channels. Seismic stratigraphy indicates that submarine, meandering channels often aggrade rapidly relative to lateral shifting, and develop channel sand bodies with high vertical connectivity. In comparison, the stratigraphic architecture developed by submarine, braided is relatively uncertain. We present a new stratigraphic model for submarine braided channels that integrates predictions from laboratory experiments and flow modeling with constraints from sediment cores. In the laboratory experiments, a saline density current developed subaqueous channels in plastic sediment. The channels aggraded to form a deposit with a vertical scale of approximately five channel depths. We collected topography data during aggradation to (1) establish relative stratigraphic age, and (2) estimate the sorting patterns of a hypothetical grain size distribution. We applied a numerical flow model to each topographic surface and used modeled flow depth as a proxy for relative grain size. We then conditioned the resulting stratigraphic model to observed grain size distributions using sediment core data from the Nankai Trough, offshore Japan. Using this stratigraphic model, we establish new, quantitative predictions for the two- and three-dimensional connectivity of coarse sediment as a function of fine-sediment fraction. Using this case study as an example, we will highlight outstanding challenges in relating the evolution of low-relief landscapes to the stratigraphic record.

Sediment DIN fluxes and preferential recycling of benthic microalgal nitrogen in a shallow macrotidal estuary

USGS Publications Warehouse

Tobias, C.; Giblin, A.; McClelland, J.; Tucker, J.; Peterson, B.

2003-01-01

Sediment-water fluxes of NH4+, NO3-, dissolved inorganic carbon, and O2 were measured in cores collected from the upper Rowley River estuary, Massachusetts, and used to calculate rates of organic nitrogen (N) mineralization, nitrification, and coupled and direct denitrification (DNF). The cores contained 15N label in benthic microalgae (BMA) and in NO3- in the overlying water as a result of an ongoing whole-estuary 15NO 3- enrichment study (NISOTREX II). The tracer allowed for estimation of gross NO3- regeneration in sediments and the contribution of BMA derived N to total mineralization. The mean mineralization rate between sites was 16.0 ?? 2.0 mmol N m-2 d-1. Approximately 13 to 56% of the mineralized N was nitrified at rates ranging from 1.8 to 10.1 mmol N m-2 d-1. Total denitrification was dominated by direct DNF (3.6 mmol N m-2 d -1) furthest upstream, where NO3- concentrations were highest. Coupled DNF was most important (8.0 mmol N m -2 d-1) in the sediments with high nitrification and low water column NO3-. A gross NO3- flux from sediments to water of 0.9 to 2.1 mmol N m-2 d-1 was estimated from the isotope dilution of ??15NO 3- in the overlying water of the cores. The isotope dilution seen in the cores was also detected as a deviation from conservative ??15NO3- mixing along estuarine transects. Incorporation of this NO3- regeneration into the DNF calculations effectively increased the estimate of direct DNF by up to 50% and decreased the coupled DNF estimate by up to 220%. Increasing ?? 15NH4+ in the water of the cores indicated that the 15N-labelled BMA were preferentially mineralized over bulk sediment organic N. Additional 15N enrichments in the sediment bacterial biomarker diaminopimelic acid showed a link among 15N-labeled BMA, active bacteria, and 15NH 4+released to the overlying water. Based on ?? 15NH4+ enrichments in the cores, BMA accounted for approximately 50 to 100% of the N mineralized. An isotopic enrichment of ??15NH4+ above background in the estuary was observed at a magnitude consistent with the core-based rates of BMA mineralization. These results provide further evidence that BMA are not unidirectional sinks for water column-dissolved organic nitrogen, but instead act to turn over N between sediments and estuarine water on the scale of days.

A 150 kyr-long hydroclimate record from Southern California using Searles Lake sediments: initial findings

NASA Astrophysics Data System (ADS)

Stroup, J. S.; Olson, K. J.; McGee, D.; Lowenstein, T. K.; Smoot, J. P.; Janick, J. J.; Lund, S.; Peaple, M.; Chen, C. Y.; Feakins, S. J.; Litwin, R.

2017-12-01

Over decadal to millennial scales, the southwestern U.S has experienced large shifts in hydroclimate ranging from pluvial conditions to extreme droughts. Direct observations, modeling and proxy data suggest precipitation amount and distribution are controlled by multiple factors including the position of the Hadley Cell, strength of the Aleutian Low and North Pacific High, ENSO and the path of winter storm tracks. Sediment records from closed basin lakes provide a means for assessing how hydrologic conditions have responded to past climate changes; however, long (>50 ka) paleoclimate records from lakes are rare and high-resolution age models are challenging to obtain. Searles Lake, in southeastern California, contains a sedimentary record that spans from the Holocene to the Pliocene at high resolution. Previous drill core studies from the basin used stratigraphy and sediment mineralogy to interpret paleoenvironmental changes and have demonstrated that the lake's sediments are able to be precisely dated. These results provide a strong foundation for new high-resolution investigations of the lake sediments. In January 2017, our group collected a new 80 m-long core with the aim of reconstructing hydrologic changes over the last 150 ka at millennial or better resolution. The core was split at the National Lacustrine Core Facility (LacCore) in June. The core contains alternating evaporite layers and finely laminated muds which likely indicate times of dryer and wetter conditions. Despite the challenge of alternating lithologies, core recovery and quality are extremely high. Here, we will present our initial chronological and stratigraphic findings. The core record will be dated using a combination of U/Th, 14C and magnetostratigraphy. We will compare our initial stratigraphic description to the existing Searles Lake literature as well as other records from the region, such as data from Devils Hole. These results provide the framework upon which we will develop detailed stratigraphic and crystallographic interpretations as well as a host of proxy records including leaf waxes, pollen and stable isotopes to advance our understanding of paleoenvironment and paleoclimate.

Geochemistry and magnetic sediment distribution at the western boundary upwelling system of southwest Atlantic

NASA Astrophysics Data System (ADS)

Cruz, Anna P. S.; Barbosa, Catia F.; Ayres-Neto, Arthur; Munayco, Pablo; Scorzelli, Rosa B.; Amorim, Nívea Santos; Albuquerque, Ana L. S.; Seoane, José C. S.

2018-02-01

In order to investigate the chemical and magnetic characteristics of sediments of the western boundary upwelling system of Southwest Atlantic we analyzed magnetic susceptibility, grain size distribution, total organic carbon, heavy mineral abundance, Fe associated with Mössbauer spectra, and Fe and Mn of pore water to evaluate the deposition patterns of sediments. Four box-cores were collected along a cross-shelf transect. Brazil Current and coastal plume exert a primary control at the inner and outer shelf cores, which exhibited similar depositional patterns characterized by a high abundance of heavy minerals (mean 0.21% and 0.08%, respectively) and very fine sand, whereas middle shelf cores presented low abundances of heavy minerals (mean 0.03%) and medium silt. The inner shelf was dominated by sub-angular grains, while in middle and outer shelf cores well-rounded grains were found. The increasing Fe3+:Fe2+ ratio from the inner to the outer shelf reflects farther distance to the sediment source. The outer shelf presented well-rounded minerals, indicating abrasive processes as a result of transport by the Brazil Current from the source areas. In the middle shelf, cold-water intrusion of the South Atlantic Central Water contributes to the primary productivity, resulting in higher deposition of fine sediment and organic carbon accumulation. The high input of organic carbon and the decreased grain size are indicative of changes in the hydrodynamics and primary productivity fueled by the western boundary upwelling system, which promotes loss of magnetization due to the induction of diagenesis of iron oxide minerals.

The relationship between the high-density lamina and precipitation in the subarctic Lake Mokoto, North Japan

NASA Astrophysics Data System (ADS)

Seto, K.

2015-12-01

Koji Seto (ReCCLE, Shimane Univ.), Hiroyuki Takata (Pusan Univ.), Kota Katsuki (KIGAM), Takeshi Sonoda (Tokyo Univ. of Agr.) In the coastal area of the Sea of Okhotsk in the east part of Hokkaido located to for subarctic zone, many brackish-water lakes are distributed. Lake Mokoto has two-layer structure of polyhaline surface waters and mixoeuhaline bottom water. The bottom water shows the anoxic conditions in summer season. In this reason, the sediments of Lake Mokoto consist of organic mud with the lamination. The 09Mk-1C and 09Mk-2C cores collected from Lake Mokoto at 2009. In the soft X-ray photograph, the cyclic lamina set is observed in their core. The cyclic lamina set consists of low-, intermedium- and high-density lamina. It is considered that this cyclic lamina set is the verve. According to the meteorological data in Abashiri region, the annually precipitation is high from August to September. Probably, the cyclic lamina set is formed by seasonal change of precipitation. In this study, we are discussed about the relationship between the high-density lamina and precipitation by sedimentologic and geochemical high-resolution analysis. The 09Mk-1C and 09Mk-2C cores collected from Lake Mokoto show the length of 1.78 to 3.87m, respectively. In 09Mk-2C core, Ta-a tephra (AD 1739) was observed at the 3.5m depths. The 09Mk-1C core consist of organic mud with the lamination in all cores. The core top 100 cm in this core shows the black (N1.5/0), and it seems to indicate the seasonal anoxic environment as present. The organic mud below 100cm depth shows black (10YR1.7/1). The sedimentation rate in 09Mk-1C core increase from late 1960's for the age of cyclic lamina set. It is suggest that supply of sediment in Lake Mokoto is increasing by land development in drainage basin. Phosphorus flux in 09Mk-1C core increase from late 1950's. The increasing of phosphorus flux may be caused by excess drainage of pollution from stock farm. In 2015, we were able to take the new core (15Mk-3C core). We have observed a new lamina set in detail, and compared with precipitation in Abashiri Region.

Evaluation and use of a diffusion-controlled sampler for determining chemical and dissolved oxygen gradients at the sediment-water interface

USGS Publications Warehouse

Simon, N.S.; Kennedy, M.M.; Massoni, C.S.

1985-01-01

Field and laboratory evaluations were made of a simple, inexpensive diffusion-controlled sampler with ports on two sides at each interval which incorporates 0.2-??m polycarbonate membrane to filter samples in situ. Monovalent and divalent ions reached 90% of equilibrium between sampler contents and the external solution within 3 and 6 hours, respectively. Sediment interstitial water chemical gradients to depths of tens of centimeters were obtained within several days after placement. Gradients were consistent with those determined from interstitial water obtained by centrifugation of adjacent sediment. Ten milliliter sample volumes were collected at 1-cm intervals to determine chemical gradients and dissolved oxygen profiles at depth and at the interface between the sediment and water column. The flux of dissolved species, including oxygen, across the sediment-water interface can be assessed more accurately using this sampler than by using data collected from benthic cores. ?? 1985 Dr W. Junk Publishers.

Searching for order in chaos: a sediment stratigraphical study of a multiple-impacted bay of the Baltic Sea

NASA Astrophysics Data System (ADS)

Vaalgamaa, S.; Korhola, A.

2004-02-01

The lithological and geochemical properties of sediment cores collected from a heavily impacted embayment in the Gulf of Finland, Baltic Sea, were investigated. Hillonlahti Bay has been the focus of much human activity, including timber and oil industries, transportation, housing, dredging and waste discharge, thus constituting an exceptionally challenging environment for sediment studies. A total of nine cores were sampled along perpendicular transects across the elongated bay, and described lithologically in the field. Major and trace element concentrations were determined for a "master core" taken from the central area of the bay. The vertical distribution of 210Pb, 137Cs and spheroidal carbonaceous particles (SCP) was also examined in order to provide a chronological framework for the sediment. Changes in the sediment nature and differences in the distributions of soluble heavy metals (Cd, Cr, Cu, Ni, V, Zn), lithophilous (Al, Ti, K, Mg, Ca, Na), redox-sensitive (Fe, Mn), and nutrient (TP) elementary concentrations were related to temporal and spatial processes. These include the building of the Hamina port starting in the mid-1930s, establishment of the timber and oil industry in 1950-1960s, construction of railway embankments in 1950 and 1996, increasing urbanisation from 1960s, and wastewater discharge between 1950 and 1987. The use of Cr as a preservative in the wood processing industry is reflected in the marked enrichment of Cr in the sediment, while the influence of wastewater discharge can be seen in the sediment record by a rise in concentrations of P and evidently organically bound Na, Cu and Zn. The results are encouraging in demonstrating that via a rather simple repertoire of sediment-analytical methods it is possible to obtain information about the land-use history and contamination in such a strongly rampaged system.

A History of Warming Sea Surface Temperature and Ocean Acidification Recorded by Planktonic Foraminifera Geochemistry from the Santa Barbara Basin, California

NASA Astrophysics Data System (ADS)

Osborne, E.; Thunell, R.; Bizimis, M.; Buckley, W. P., Jr.; benitez-Nelson, C. R.; Chartier, C. J.

2015-12-01

The geochemistry of foraminiferal shells has been widely used to reconstruct past conditions of the ocean and climate. Since the onset of the Industrial Revolution, anthropogenically produced CO2 has resulted in an increase in global temperatures and a decline in the mean pH of the world's oceans. The California Current System is a particularly susceptible region to ocean acidification due to natural upwelling processes that also cause a reduction in seawater pH. The trace element concentration of magnesium and boron in planktonic foraminiferal shells are used here as proxies for temperature and carbonate ion concentration ([CO32-]), respectively. Newly developed calibrations relating Mg/Ca ratios to temperature (R2 0.91) and B/Ca ratios to [CO32-] (R2 0.84) for the surface-mixed layer species Globogerina bulloides were generated using material collected in the Santa Barbara Basin sediment trap time-series. Using these empirical relationships, temperature and [CO32-] are reconstructed using a 0.5 meter long multi-core collected within the basin. 210Pb activities were used to determine a sedimentation rate for the core to estimate ages for core samples (sedimentation rate: 0.341 cm/yr). A spike in 137Cs activity is used as a tie-point to the year 1965 coinciding with the peak of nuclear bomb testing. Our down-core record extends through the mid-19th century to create a history of rising sea surface temperatures and declining [CO32-] as a result of anthropogenic CO2 emissions.

Insight into metabolic potential of carbon-poor pelagic sediments derived from the abundance and composition of organic carbon

NASA Astrophysics Data System (ADS)

Estes, E. R.; Hansel, C. M.; Orsi, W. D.; Anderson, C. H.; Murray, R. W.; Wankel, S. D.; Johnson, D.; Nordlund, D.; Spivack, A. J.; Sauvage, J.; McKinley, C. C.; Homola, K.; Present, T. M.; Pockalny, R. A.; D'Hondt, S.

2016-02-01

Pelagic marine sediments are often carbon-limited, with oxic sediments bearing exceedingly small concentrations of metabolizable organic carbon (OC) and anoxic sediments lacking electron acceptors to drive heterotrophy. This OC is typically considered recalcitrant and presumed to be of limited bioavailability as much of it is difficult to characterize molecularly. Here, we utilize a combination of spectrometry, spectroscopy, and fluorescent assays to characterize the OC content and composition of sediment cores from the western subtropical North Atlantic collected during R/V Knorr expedition 223 in November 2014. We find that OC concentrations decrease linearly over 15m burial depth from 0.15 to 0.075 mol OC/kg sediment, beyond which this lower OC level persists to depths approaching 30m. The ratio of organic carbon to nitrogen (C/N) varies but is consistently close to Redfield values of 6. Further, protein concentrations within the suboxic sediments are 1.75 to 4.90 μg protein/mg sediment, values in excess of predicted cell abundance in subsurface sediments. After an initial decrease in concentration between 0-3 meters below core top, protein content increases and stabilizes at 4 μg protein/mg sediment. RNA is detectable throughout the core and profiles (as μg cDNA amplified/g sediment) generally correlate with the shape of protein profiles. Combined, these results imply a small but active microbial community and the potential for these proteins to fuel heterotrophy at depth. Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy finds that amide and carboxyl C functionalities comprise 25% of total spectral area, with the remainder dominated by aromatic C and O-alkyl-C groups. These findings suggest that sedimentary OC contain identifiable components, including a substantial concentration of intact proteins that may fuel heterotrophic microbial communities.

Persistence of nonylphenol ethoxylate surfactants and their primary degradation products in sediments from near a municipal outfall in the Strait of Georgia, British Columbia, Canada

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shang, D.Y.; Macdonald, R.W.; Ikonomou, M.G.

1999-05-01

Marine sediment cores and surface grabs were collected from the Strait of Georgia, British Columbia, Canada, near the Iona municipal outfall and were analyzed for nonylphenol (NP) and its ethoxylate compounds (NPnEOs). The authors used normal-phase liquid chromatography with electrospray mass spectrometric detection to determine concentrations of ethoxylates from n = 1 to n = 19. Over half the NPnEO inventory in marine sediments resides in ethoxylates of chain length greater than n = 2, suggesting that analyses limited to short-chain ethoxylates (n = 2) are under-reporting total NPnEO by a factor of 2. The NPnEO vertical profiles and oligomermore » distributions in dated sediment cores suggest that little degradation occurs once these compounds enter the sediments: the half-life for these compounds is estimated to be greater than 60 yr. The lack of change in NPnEO oligomer distribution with age suggests that degradation by chain shortening does not occur significantly. A rough inventory shows that over 30 t of NPnEO resides in Fraser River Delta sediments near the Iona municipal outfall and that the entire Strait of Georgia sediments contain over 170 t of NPnEO.« less

Saltmarsh creek bank stability: Biostabilisation and consolidation with depth

NASA Astrophysics Data System (ADS)

Chen, Y.; Thompson, C. E. L.; Collins, M. B.

2012-03-01

The stability of cohesive sediments of a saltmarsh in Southern England was measured in the field and the laboratory using a Cohesive Strength Meter (CSM) and a shear vane apparatus. Cores and sediment samples were collected from two tidal creek banks, covered by Atriplex portulacoides (Sea Purslane) and Juncus maritimus (Sea Rush), respectively. The objectives of the study were to examine the variation of sediment stability throughout banks with cantilevers present and investigate the influence of roots and downcore consolidation on bank stability. Data on erosion threshold and shear strength were interpreted with reference to bank depth, sediment properties and biological influences. The higher average erosion threshold was from the Sea Purslane bank whilst the Sea Rush bank showed higher average vane shear strength. The vertical variation in core sediment stability was mainly affected by roots and downcore consolidation with depth. The data obtained from the bank faces revealed that vertical variations in both erosion threshold and vane shear strength were affected primarily by roots and algae. A quantitative estimate of the relative contributions of roots and downcore consolidation to bank sediment stability was undertaken using the bank stability data and sediment density data. This showed that roots contributed more to the Sea Purslane bank stability than downcore consolidation, whilst downcore consolidation has more pronounced effects on the Sea Rush bank stability.

The Late Pliocene Eltanin Impact - Documentation From Sediment Core Analyses

NASA Astrophysics Data System (ADS)

Gersonde, R.; Kuhn, G.; Kyte, F. T.; Flores, J.; Becquey, S.

2002-12-01

The expeditions ANT-XII/4 (1995) and ANT-XVIII/5a (2001) of the RV POLARSTERN collected extensive bathymetric and seismic data sets as well as sediment cores from an area in the Bellingshausen Sea (eastern Pacific Southern Ocean) that allow the first comprehensive geoscientific documentation of an asteroid impact into a deep ocean (~ 5 km) basin, named the Eltanin impact. Impact deposits have now been recovered from a total of more than 20 sediment cores collected in an area covering about 80,000 km2. Combined biomagnetostratigraphic dating places the impact event into the earliest Matuyama Chron, a period of enhanced climate variability. Sediment texture analyses and studies of sediment composition including grain size and microfossil distribution reveal the pattern of impact-related sediment disturbance and the sedimentary processes immediately following the impact event. The pattern is complicated by the San Martin Seamounts (~57.5 S, 91 W), a large topographic elevation that rises up to 3000 m above the surrounding abyssal plain in the area affected by the Eltanin impact. The impact ripped up sediments as old as Eocene and probably Paleocene that have been redeposited in a chaotic assemblage. This is followed by a sequence sedimented from a turbulent flow at the sea floor, overprinted by fall-out of airborne meteoritic ejecta that settled trough the water column. Grain size distribution reveals the timing and interaction of the different sedimentary processes. The gathered estimate of ejecta mass deposited over the studied area, composed of shock-melted asteroidal matrial and unmelted meteorites including fragments up to 2.5 cm in diameter, point to an Eltanin asteroid larger than the 1 km in diameter size originally suggested as a minimum based on the ANT-XII/4 results. This places the energy released by the impact at the threshold of those considered to cause environmental disturbance at a global scale and it makes the impact a likely transport mechanism explaining the presence of extinct Cenozoic microfossils in the transantarctic Sirius Unit. Although a crater structure representing Eltanin ground zero has not been discovered, the distribution pattern of sediment disturbance and ejecta deposits now allows to better determine the central target area north of the San Martin Seamounts.

The Late Pliocene Eltanin Impact: Documentation From Sediment Core Analyses

NASA Technical Reports Server (NTRS)

Gersonde, R.; Kyte, F.; Flores, J. A.; Becquey, S.

2002-01-01

The expeditions ANT-XII/4 (1995) and ANT-XVIII/5a (2001) of the RV POLARSTERN collected extensive bathymetric and seismic data sets as well as sediment cores from an area in the Bellingshausen Sea (eastern Pacific Southern Ocean) that allow the first comprehensive geoscientific documentation of an asteroid impact into a deep ocean (approx. 5 km) basin, named the Eltanin impact. Impact deposits have now been recovered from a total of more than 20 sediment cores collected in an area covering about 80,000 km2. Combined biomagnetostratigraphic dating places the impact event into the earliest Matuyama Chron, a period of enhanced climate variability. Sediment texture analyses and studies of sediment composition including grain size and microfossil distribution reveal the pattern of impact- related sediment disturbance and the sedimentary processes immediately following the impact event. The pattern is complicated by the San Martin Seamounts (approx. 57.5 S, 91 W), a large topographic elevation that rises up to 3000 m above the surrounding abyssal plain in the area affected by the Eltanin impact. The impact ripped up sediments as old as Eocene and probably Paleocene that have been redeposited in a chaotic assemblage. This is followed by a sequence sedimented from a turbulent flow at the sea floor, overprinted by fall-out of airborne meteoritic ejecta that settled trough the water column. Grain size distribution reveals the timing and interaction of the different sedimentary processes. The gathered estimate of ejecta mass deposited over the studied area, composed of shock-melted asteroidal material and unmelted meteorites including fragments up to 2.5 cm in diameter, point to an Eltanin asteroid larger than the 1 km in diameter size originally suggested as a minimum based on the ANT-XII/4 results. This places the energy released by the impact at the threshold of those considered to cause environmental disturbance at a global scale and it makes the impact a likely transport mechanism explaining the presence of extinct Cenozoic microfossils in the transantarctic Sirius Unit. Although a crater structure representing Eltanin ground zero has not been discovered, the distribution pattern of sediment disturbance and ejecta deposits now allows to better determine the central target area north of the San Martin Seamounts.

DDTs and HCHs in sediment cores from the Tibetan Plateau.

PubMed

Cheng, Hairong; Lin, Tian; Zhang, Gan; Liu, Guoqing; Zhang, Weiling; Qi, Shihua; Jones, Kevin C; Zhang, Xuewen

2014-01-01

Sediment cores were collected from five critical regions in the Tibetan Plateau and were analysed for OCPs with the objective of examining the time trends and recycling of DDTs and HCHs in the cryogenic area. A concurrent increase of the DDT and HCH concentrations from the late 1980s in Lake Yamzho Yumco, Nam Co and Star Sea were observed. The increasing levels of DDE/DDTs (>0.4) suggested that DDT in the upper layers of the sediment cores may be recycled/"weathered" DDT. Regarding the acceleration of glacier retreat from the 1980s due to global warming, it is suggested that OCPs formerly trapped either in the snow/glacier or in the frozen soil land recently reclaimed in the processes of glacier retreat may have been flushed into the sedimentary basins. These findings demonstrate the potential impact of global warming on the recycling of POPs in the plateau cryosphere and indicate that the pristine Tibetan Plateau may serve as one of the key probes to the global trend of POPs. Copyright © 2013 Elsevier Ltd. All rights reserved.

Evolution of Metallic Trace Elements in Contaminated River Sediments: Geochemical Variation Along River Linear and Vertical Profile

NASA Astrophysics Data System (ADS)

Kanbar, Hussein; Montarges-Pelletier, Emmanuelle; Mansuy-Huault, Laurence; Losson, Benoit; Manceau, Luc; Bauer, Allan; Bihannic, Isabelle; Gley, Renaud; El Samrani, Antoine; Kobaissi, Ahmad; Kazpard, Veronique; Villieras, Frédéric

2015-04-01

Metal pollution in riverine systems poses a serious threat that jeopardizes water and sediment quality, and hence river dwelling biota. Since those metallic pollutants can be transported for long distances via river flow, river management has become a great necessity, especially in times where industrial activities and global climate change are causing metal release and spreading (by flooding events). These changes are able to modify river hydrodynamics, and as a consequence natural physico-chemical status of different aquatic system compartments, which in turn alter metal mobility, availability and speciation. Vertical profiles of sediments hold the archive of what has been deposited for several tenths of years, thus they are used as a tool to study what had been deposited in rivers beds. The studied area lies in the Orne river, northeastern France. This river had been strongly modified physically and affected by steelmaking industrial activities that had boosted in the middle of the last century. This study focuses on several sites along the linear of the Orne river, as well as vertical profiles of sediments. Sediment cores were collected at sites where sedimentation is favoured, and in particular upstream two dams, built in the second half of the XXth century for industrial purposes. Sediment cores were sliced into 2-5cm layers, according to suitability, and analysed for physical and physico-chemical properties, elemental content and mineralogy. Data of the vertical profile in a sediment core is important to show the evolution of sediments as a function of depth, and hence age, in terms of nature, size and constituents. The physical properties include particle size distribution (PSD) and water content. In addition, the physico-chemical properties, such as pH and oxido-reduction potential (ORP) of interstitial water from undisturbed cores were also detected. Total elemental content of sediment and available ones of extracted interstitial waters was detected using ICP-MS and ICP-OES for trace and major elements respectively. Well crystallized minerals were detected by X-Ray Diffraction (XRD), while amorphous and poorly crystallized phases were identified with scanning and transmission electron microscope (SEM and TEM respectively), combined with Energy Dispersive X-Ray Spectroscopy (EDXS). Such microscopic techniques also provided information about metal carriers. To have an insight about the metal speciation at molecular level, X-Ray Absorption spectroscopy (XAS) was performed at Zn K-edge. The first analyses of Orne sediment cores evidenced different particle size distribution and sediment consolidation levels. Yet the cores showed that below a layer of apparently recent sediments (about 10-20 cm), lie highly contaminated ones. Zn and Pb content in deep sediment layers reach several thousands ppm, where they appeared mainly as Zn and Pb sulphides. Also, the high content of iron in deep sediments resulted in the presence of different iron phases: hematite, wuestite, magnetite, goethite, sulphides (pyrite), as well as undefined iron-silicate. In addition, interstitial waters contained high values of available metals (Zn: 500-35000 ppm, Pb: 150-5700 ppm, Cd: 1-10ppm), which might cause a greater concern than solid-bound metals, especially when river bed sediments are disturbed.

PSV records from sediments of modern lakes (Aslikyl, Svir, Naroch).

NASA Astrophysics Data System (ADS)

Kuzina, D.; Kosareva, L.; Nourgaliev, D.; Kosarev, V.

2014-12-01

During the last 20 years, our paleomagnetic group had investigated many lakes with the aim to know the behavior of the geomagnetic field during the Holocene. Lake sediments are the good presenters of the paleosecular variation (PSV) records. In this paper are presented materials from Lakes Aslikul (Russia, 54o 25' N, 54o 07' E), Svir (Belorussia, 54o 47' N; 26o 30' E), Naroch (Belorussia, 54o 51' N, 26o 51' E). Samples of lake floor sediments were collected using a piston corer designed and manufactured at the Kazan University as a prototype were used piston corer which had been designed and used by F. J. H. Mackereth. Three cores were collected from each Lake Aslikul and Svir and six cores from Lake Naroch. Cores length was between 3,5-6,5 meters. Sediments were subsampled into cubic nonmagnetic plastic boxes. Their magnetic susceptibilities were then measured using a MS2-B instrument, and their natural remanent magnetization (NRM) (module and direction) was measured using a JR-4 magnetometer. Based on this data were built generalized record for each parameter. We compared the geomagnetic field variations recorded in our study with the records reported in the literature for the sediments in the different lakes. Our data have a good PSV records correlation with other data so we can obtain age of sediments according to PSV records. The dating of lakes sediments was also improved and further detailed by radiocarbon dating that gave the same results. Some characteristic features, the B and S minima and the Y and E maxima (cf. nomenclature of Thompson and Turner, 1982) are recognized. All peaks have a wide but complicated structure. Studied lakes compared to the other European records available, it can be concluded that the PSV master curves obtained in this study can be used to model Holocene geomagnetic variations. The work is performed according to the Russian Government Program of Competitive Growth of Kazan Federal University also by RFBR research projects No. 14-05-00785- а.

A Comparison of Naturally-Occurring and Artificially Stimulated Uranium(VI) Bioreduction in Sediment from a Field-scale Experiment in Rifle, CO

NASA Astrophysics Data System (ADS)

Campbell, K. M.; Williams, K. H.; Lesher, E.; Davis, J. A.; Long, P. E.

2007-12-01

Long-term remediation of uranium (U)-contaminated groundwater poses one of the greatest challenges in the clean-up of impacted sites. One solution is to reduce dissolved U(VI) to insoluble U(IV) precipitates by stimulating indigenous metal reducing bacterial populations in situ. Contamination from a former U mine tailings repository (Rifle, CO) provides a research site to study the efficacy of biostimulated U(VI) reduction at the field scale. Several cores were drilled in June 2007 across a region of naturally-occurring U(VI) bioreduction. The cores represent a cross section of sediment that ranges from minimally reducing to highly reducing. Anaerobic sediment samples from the cores were analyzed for labile U(VI) content by carbonate extraction in anoxic conditions (pH 9.4, 14 mM NaHCO3, 2.8 mM Na2CO¬3). A subset of the same core sections were dried and oxidized by exposure to air for 2 weeks. The carbonate extraction was repeated, and the amount of U(IV) present in the anaerobic sample was calculated by difference between the anoxic and oxidized extractions. An acid extraction was also performed on the oxidized sediments to compare the carbonate extractable and the acid extractable U fractions. The highest U concentrations were found in the highly bioreduced sediment, with the majority of U present as U(IV) (66-92%). The regions of highest bioreduction also correspond to elevated concentrations of solid phase organic carbon, suggesting that natural bioreduction is stimulated by zones of increased organic carbon content. The same field site was then used for an artificially stimulated bioreduction experiment, where the indigenous bacterial community was stimulated by injecting acetate upgradient of the core collection location. Carbonate and acid extractions were performed on core samples taken after the completion of the acetate injection. This work evaluates the composition of the sediment before and after biostimulation as a way of directly comparing the extent of natural U(VI) bioreduction to acetate-stimulated bioreduction in order to facilitate the design of a more effective bioremediation strategy for this site.

The Impact of the 1989 Exxon Valdez Oil Spill on Phytoplankton as Evidenced Through the Sedimentary Dinoflagellate Cyst Records in Prince William Sound (Alaska, USA).

NASA Astrophysics Data System (ADS)

Genest, M.; Pospelova, V.; Williams, J. R.; Dellapenna, T.; Mertens, K.; Kuehl, S. A.

2016-12-01

Large volumes of crude oil are extracted from marine environments and transported via the sea, putting coastal communities at a greater risk of oils spills. It is therefore crucial for these communities to properly assess the risk. The first step is to understand the effects of such events on the environment, which is limited by the lack of research on the impact of oil spills on phytoplankton. This first-of-its-kind research aims to identify how one of the major groups of phytoplankton, dinoflagellates, have been affected by the 1989 Exxon Valdez oil spill in Prince William Sound (PWS), Alaska. To do this, sedimentary records of dinoflagellate cysts, produced during dinoflagellate reproduction and preserved in the sediment, were analyzed. Two sediment cores were collected from PWS in 2012. The sediments are mainly composed of silt with a small fraction of clay. Both well-dated with 210Pb and 137Cs, the cores have high sedimentation rates, allowing for an annual to biannual resolution. Core 10 has a sedimentation rate of 1.1 cm yr-1 and provides continuous record since 1957, while Core 12 has a sedimentation rate of 1.3 cm yr-1 and spans from 1934. The cores were subsampled every centimeter for a total of 110 samples. Samples were treated using a standard palynological processing technique to extract dinoflagellate cysts and 300 cysts were counted per sample. In both cores, cysts were abundant, diverse and well preserved with the average cyst assemblage being characterized by an equal number of cysts produced by autotrophic and heterotrophic dinoflagellates. Of the 40 dinoflagellate cyst taxa, the most abundant are: Operculodinium centrocarpum and Brigantedinium spp. Other common species are: Spiniferites ramosus, cysts of Pentapharsodinium dalei, Echinidinium delicatum, E. zonneveldiae, E. transparantum, Islandinium minutum, and a thin pale brown Brigantedinium type. Changes in the sedimentary sequence of dinoflagellate cysts were analyzed by determining cyst relative abundances, species richness, total cyst concentrations and fluxes before, during and after the oil spill. This analysis provided insight into how phytoplankton can be affected by an oil spill and a timeline for their recovery.

Ancient deep-sea sponge grounds on the Flemish Cap and Grand Bank, northwest Atlantic.

PubMed

Murillo, F J; Kenchington, E; Lawson, J M; Li, G; Piper, D J W

Recent studies on deep-sea sponges have focused on mapping contemporary distributions while little work has been done to map historical distributions; historical distributions can provide valuable information on the time frame over which species have co-evolved and may provide insight into the reasons for their persistence or decline. Members of the sponge family Geodiidae are dominant members of deep-sea sponge assemblages in the northwestern Atlantic. They possess unique spicules called sterrasters, which undergo little transport in sediment and can therefore indicate the Geodiidae sponge historical presence when found in sediment cores. This study focuses on the slopes of Flemish Cap and Grand Bank, important fishing grounds off the coast of Newfoundland, Canada, in international waters. Sediment cores collected in 2009 and 2010 were visually inspected for sponge spicules. Cores containing spicules were sub-sampled and examined under a light microscope for the presence of sterrasters. These cores were also dated using X-radiographs and grouped into five time categories based on known sediment horizons, ranging from 17,000 years BP to the present. Chronological groupings identified Geodiidae sponges in four persistent sponge grounds. The oldest sterrasters were concentrated in the eastern region of the Flemish Cap and on the southeastern slope of the Grand Bank. Opportunistic sampling of a long core in the southeastern region of the Flemish Cap showed the continuous presence of sponge spicules to more than 130 ka BP. Our results indicate that the geodiids underwent a significant range expansion following deglaciation, and support a contemporary distribution that is not shaped by recent fishing activity.

A paleomagnetic and relative paleointensity record from the Argentine Basin (western South Atlantic Ocean) for the last ~125 kyrs

NASA Astrophysics Data System (ADS)

Heil, C. W., Jr.; Stoner, J. S.; St-Onge, G.; King, J. W.

2015-12-01

The paucity of paleomagnetic records from the western South Atlantic Ocean presents a significant gap in our understanding of the spatial variations in geomagnetic field dynamics as they relate to the occurrence of geomagnetic excursions and changes in field strength. As such, high quality records from this region can help build upon Holocene observations and extend the geographic and temporal data coverage for spherical harmonic models. To that end, we present paleomagnetic directional (inclination) and strength (relative paleointensity) records from two cores from the Argentine Basin (RC11-49 and RC16-88). Although the cores were collected more than 40 years ago, the sediments appear to hold a stable remanence and reliable magnetic directions, as evidenced by their reproducibility between the two cores that are separated by ~25 km. The records show evidence of 4 excursional features in the uppermost 16-m of the sediments from the basin. A comparison of the relative paleointensity records from these cores to the South Atlantic Paleointensity Stack (SAPIS) (Stoner et al., 2002) and the relative paleointensity record from ODP Site 1089 (Stoner et al., 2003) indicate that the sediments reliably record relative changes in geomagnetic field intensity and suggests that the longest record (RC11-49) spans the last ~125 kyrs. Our results indicate that the sediments of the Argentine Basin are an important sedimentary archive of geomagnetic field behavior and strength at least through the Holocene and Late Pleistocene and highlight the need for further studies of cores within the basin.

Metal distribution in sediment cores from São Paulo State Coast, Brazil.

PubMed

Silva, Paulo S C; Damatto, Sandra R; Maldonado, Caio; Fávaro, Deboráh I T; Mazzilli, Barbara P

2011-05-01

Ten sediment core samples with lengths ranging from 35 to 100 cm were collected in the Baixada Santista region and analyzed to determine As, Br, Co, Cr, Cs, Fe, Rb, Sb, Ta, Th, U, Zn and rare earths (Sc, Ce, Eu, La, Lu, Nd, Sm, Tb and Yb) level concentrations using instrumental neutron activation analysis (INAA). The studied region is located in the southeastern coast of São Paulo State and is comprised of a densely urbanized area, the largest industrial complex of the country, with a predominance of petrochemical and fertilizer plants. It is also home to Brazil's most important and busiest port. The conclusions found that the As, La, Sm, Ne, Ce, Eu, Hf, Ta, Th, and U elements have a high background level in the region and that Fe and Zn were the main indicators of anthropogenic contribution in the sediments. Copyright © 2011 Elsevier Ltd. All rights reserved.

Geochronology of Mudflow Deposits on the Mississippi River Delta Front, Louisiana, USA

NASA Astrophysics Data System (ADS)

Keller, G. P.; Bentley, S. J.; Xu, K.; Georgiou, I. Y.; Miner, M. D.; Obelcz, J.; Maloney, J. M.

2016-02-01

Short multicores (<50cm) and longer gravity cores (up to 3m) were collected seaward of the Southwest Pass of the Mississippi River Delta (Gulf of Mexico) and were analyzed to assess the frequency, extent, and potential causes of submarine mass wasting events. Cores were analyzed for radionuclide activity, grain size, and density at 2cm resolution, with x-radiography for the whole core. Short-term sedimentation rates calculated from 7Be are 2-12cm/y, while longer-term accumulation from 210Pb are only 1.3-5.5cm/y. In most cores, 210Pb activity steadily decreases downcore without displaying a "stairstep" nature. However, six cores have layers of low 210Pb activity stratigraphically above layers with higher activity. In one long core from a mudflow gully, 210Pb steadily decreases for the upper 90cm before stabilizing for the remaining 130cm. Clay content generally ranges between 25-40% and sand ranges between 5-15% with silt making up the rest of each sample. Sedimentation rates derived from 210Pb in the short cores indicate that proximity to the river mouth has stronger influence than depositional environment (mudflow gully, depositional lobe, prodelta). This finding may be explained by rapid sedimentation rates coupled with a reduced tropical cyclone activity over the delta in the last seven years (2006-2013). The regions of decreased 210Pb activity may be evidence of scavenging effects of plume sedimentation because they do not correspond with decreases in clay fraction. The zone of homogenized activity below 90cm in the gully core occurs at a depth equivalent to 18 years, indicating mixing on a decadal scale, potentially from mudflows. These results may be explained by a lack of recent mass failures corresponding with lulls in tropical cyclone activity over the delta, preceded by a period of more active hurricane-driven mudflow activity.

Is the Core Top Really Modern? A Story of Chemical Erosion, Bioturbation, and Lateral Sediment Redistribution from the Eastern Equatorial Pacific

NASA Astrophysics Data System (ADS)

Mekik, F.

2016-12-01

Paleoceanographic work is based on calibrating paleo-environmental proxies using well-preserved core top sediments which represent the last one thousand years or less. However, core top sediments may be in places as old as 9000 years due to various sedimentary and diagenetic processes, such as chemical erosion, bioturbation and lateral sediment redistribution. We hypothesize that in regions with high surface ocean productivity, high organic carbon to calcite ratios reaching the seabed promote calcite dissolution in sediments, even in regions above the lysocline. This process may lead to chemical erosion of core tops which in turn may result in core top aging. The eastern equatorial Pacific (EEP), a popular site for calibration of paleoceanographic proxies, is such a place. Better understanding the relationship between core top age and dissolution will help correct biases inherent in proxy calibration because dissolution of foraminifers alters shell chemistry, and wholesale dissolution of sediments leads to core top aging and loss. We present both new and literature-based core top data of radiocarbon ages from the EEP. We created regional maps of both core top radiocarbon age and calcite preservation measured with the Globorotalia menardii Fragmentation Index (MFI; over 100 core tops). Our maps show a clear pattern of deep sea sedimentary calcite dissolution mimicking the pattern of surface ocean productivity observed from satellites and sediment traps in the EEP. Core top radiocarbon ages generally parallel the dissolution patterns observed in the region. Where this relationship does not hold true, bioturbation and/or lateral sediment redistribution may play a role. Down core radiocarbon and 230Th-normalized sediment accumulation rate data from several cores in the EEP support this hypothesis. Better understanding the role of diagenesis promotes the development of more reliable paleo-environmental proxies.

Phosphorus geochemistry of recent sediments in the South Basin of Lake Winnipeg

USGS Publications Warehouse

Mayer, T.; Simpson, S.L.; Thorleifson, L.H.; Lockhart, W.L.; Wilkinson, Philip M.

2006-01-01

Lake Winnipeg supports the largest commercial fishery on Canadian Prairies. It has been influenced by a variety of environmental forces and anthropogenic activities. To gain a better understanding of recent changes in nutrient status of the lake, it is important to reconstruct its previous history from sedimentary records. Lacustrine sediments are known to be an important sink of many dissolved and suspended substances, including phosphorus, hence, they provide a permanent historical record of changes occurring in the lake. These changes may be induced by natural factors or by anthropogenic activities in the watershed. Phosphorus profiles from dated sediment cores collected in 1999 and 1994 from the South Basin of Lake Winnipeg were investigated to determine phosphorus enrichment in recent sediments. To interpret the nutrient status and depositional conditions responsible for the trends in total phosphorus, three operationally defined forms of phosphorus (P) were determined: non-apatite inorganic P, apatite P, and organic P. Significant increases in sediment phosphorus concentrations were observed in the uppermost 20 cm of the cores and several anomalies were observed at depth. A doubling in total phosphorus relative to aluminum over the last fifty years is largely due to increases in the non-apatite inorganic fraction, suggesting that much of sedimentary phosphorus increase is attributable to changes in the nutrient status of the water column related to anthropogenic inputs. Organic phosphorus exhibits a subtle increase in the upper 20 cm of the gravity cores, likely due to increases in the primary productivity of the lake. Except for the slight increase in deeper sediments, apatite phosphorus, which is thought to be of detrital origin, remained fairly constant over the length of the cores. Anomalous spikes in phosphorus concentrations deeper in the cores, comprised mainly of the non-apatite inorganic phosphorus fraction, likely resulted from natural variation in local oxidizing conditions, possibly induced by changes in water circulation and/or changes in sediment deposition rates due to climatic variation. The results of this investigation contribute to increased understanding of the depositional history of phosphorus in the lake over the last millennium.

Tracing metal sources in core sediments of the artificial lake An-Dong, Korea: Concentration and metal association.

PubMed

Choi, Mansik; Park, Jongkyu; Cho, Dongjin; Jang, Dongjun; Kim, Miseon; Choi, Jongwoo

2015-09-15

The concentration and source of trace metals in the artificial lake An-Dong, which has widespread abandoned mines and a Zn smelter upstream of the drainage basin, were investigated. Soils (18ea), stream waters (15ea) and sediments (15ea) in the main channel and five tributaries downstream of the Zn smelter towards the lake (~ 50 km downstream) were collected. And two core sediments were also taken from the middle of the lake. All samples were analyzed for trace metals in bulk and in a 1N HCl-leached fraction. Although the soil and stream sediments consisted mostly of sand-sized grains, concentrations of metals (Cu, Zn, Cd and Pb) were very high in all samples, including soils, stream waters and sediments at sites near the Zn smelter. However the metal concentrations decreased rapidly downstream, suggesting that the area of impact of the smelter lies within 5 km. Highly enriched metal concentrations were also found in dated core sediments from the lake; while the highest concentrations of Co, Ni, As, Cu, Zn, Cd and Pb were detected in the bottom of the sediment core (dated 1980) they decreased towards 2000, and only Cu, Zn and Cd concentrations increased again in present-day samples. Since the temporal variation in metal concentrations appeared consistent with historical variation in ore mining and Zn smelter production rates, a model combining the production rates of each was developed, which estimated 3%, 12% and 7% contributions from Zn smelter compared to ore mining production rate to levels of Cu, Cd and Zn, respectively, suggesting the different pathways by different sources. In addition, analysis of Cd/Zn and Cu/Zn ratios showed that contamination from ore mining decreased from 1980 to 2000, and smelting processes were most likely responsible for metal enrichment (Cu, Cd and Zn) from 2000 to the present. Copyright © 2015 Elsevier B.V. All rights reserved.

Trace metal in sediment from a deep-sea floor of Makassar Strait

NASA Astrophysics Data System (ADS)

Budianto, F.; Lestari

2018-02-01

Makassar Strait is located in the entrance of Indonesian Through Flow (ITF). However, the geochemistry of metals in sediment within Makassar Strait remains unexplored. The aim of this study was to measure the concentration of metals in sediment and to assess the sediment quality based on those metals concentrations. The sediment was collected from 632-4730 m in depth using giant piston corer on R/V Baruna Jaya VIII in December 2014. In each observation point, three layers of sediment were sub-sampled from the core i.e. surface layer (0-5 cm), middle layer (45-55 cm) and bottom layer. The metals were analyzed using acid digestion procedure followed by Atomic Absorption Spectrophotometer. The result indicated that the metal has spatially insignificant differences in sediment and the increase of metal concentration by depth was noticed. The Enrichment factor presented as no enrichment to minor enrichment of metal in sediment.

Alteration in Solid State Phosphorous With Depth in Sediments Along the Salinity Transition Zone of a Major Chesapeake Bay Tributary

NASA Astrophysics Data System (ADS)

Hartzell, J. L.; Jordan, T. E.

2006-05-01

Determining the fate of particulate phosphorus in estuaries is essential for addressing the widespread problem of estuarine eutrophication, and is key to understanding P cycling and developing accurate global P budgets. Prominent reservoirs of P in surficial sediments include particulate P associated with iron or organic C. However, the importance of these reservoirs changes with the decomposition of organic matter and the reduction of iron. Also, the importance of iron bound P may decrease with increasing salinity due to the formation of iron sulfides. To investigate estuarine P burial and its relationship to salinity, we collected sediment cores of one-meter depth along the salinity gradient of the Patuxent River estuary (Maryland, USA), a major tributary of Chesapeake Bay. The sediments were analyzed using a sequential sedimentary extraction procedure that quantifies five separate reservoirs of particulate P. Total phosphorus concentrations in freshwater sediments were significantly higher than those in more saline sediments at all depths. Conversely, porewater phosphate concentrations were significantly lower in freshwater sediments than in the more saline sediments. Total P in the saline sediment cores decreased with depth, correlating to a reduction in iron-bound P. However, we did not find a concurrent increase in authigenic apatite with depth. Our findings indicate that mechanisms controlling changes in P sorption to sediments change profoundly with salinity and may contribute to increased bioavailability of phosphates with increasing salinity.

Global Distribution of Net Electron Acceptance in Subseafloor Sediment

NASA Astrophysics Data System (ADS)

Fulfer, V. M.; Pockalny, R. A.; D'Hondt, S.

2017-12-01

We quantified the global distribution of net electron acceptance rates (e-/m2/year) in subseafloor sediment (>1.5 meters below seafloor [mbsf]) using (i) a modified version of the chemical-reaction-rate algorithm by Wang et al. (2008), (ii) physical properties and dissolved oxygen and sulfate data from interstitial waters of sediment cores collected by the Ocean Drilling Program, Integrated Ocean Drilling Program, International Ocean Discovery Program, and U.S. coring expeditions, and (iii) correlation of net electron acceptance rates to global oceanographic properties. Calculated net rates vary from 4.8 x 1019 e-/m2/year for slowly accumulating abyssal clay to 1.2 x 1023 e-/m2/year for regions of high sedimentation rate. Net electron acceptance rate correlates strongly with mean sedimentation rate. Where sedimentation rate is very low (e.g., 1 m/Myr), dissolved oxygen penetrates more than 70 mbsf and is the primary terminal electron acceptor. Where sedimentation rate is moderate (e.g., 3 to 60 m/Myr), dissolved sulfate penetrates as far as 700 mbsf and is the principal terminal electron acceptor. Where sedimentation rate is high (e.g., > 60 m/Myr), dissolved sulfate penetrates only meters, but is the principal terminal electron acceptor in subseafloor sediment to the depth of sulfate penetration. Because microbial metabolism continues at greater depths than the depth of sulfate penetration in fast-accumulating sediment, complete quantification of subseafloor metabolic rates will require consideration of other chemical species.

Characterizing the variability of benthic foraminifera in the northeastern Gulf of Mexico following the Deepwater Horizon event (2010-2012).

PubMed

Schwing, P T; O'Malley, B J; Romero, I C; Martínez-Colón, M; Hastings, D W; Glabach, M A; Hladky, E M; Greco, A; Hollander, D J

2017-01-01

Following the Deepwater Horizon (DWH) event in 2010 subsurface hydrocarbon intrusions (1000-1300 m) and an order of magnitude increase in flocculent hydrocarbon deposition caused increased concentrations of hydrocarbons in continental slope sediments. This study sought to characterize the variability [density, Fisher's alpha (S), equitability (E), Shannon (H)] of benthic foraminifera following the DWH event. A series of sediment cores were collected at two sites in the northeastern Gulf of Mexico from 2010 to 2012. At each site, three cores were utilized for benthic faunal analysis, organic geochemistry, and redox metal chemistry, respectively. The surface intervals (∼0-10 mm) of the sedimentary records collected in December 2010 at DSH08 and February 2011 at PCB06 were characterized by significant decreases in foraminiferal density, S, E, and H, relative to the down-core intervals as well as previous surveys. Non-metric multidimensional scaling (nMDS) analysis suggested that a 3-fold increase in polycyclic aromatic hydrocarbon (PAH) concentration in the surface interval, relative to the down-core interval, was the environmental driver of benthic foraminiferal variability. These records suggested that the benthic foraminiferal recovery time, following an event such as the DWH, was on the order of 1-2 years.

Source and Fate of Sediments in the Bahia de Anasco, Puerto Rico

NASA Astrophysics Data System (ADS)

Webb, R. M.

2005-12-01

Sediments and wastewater mix in the insular marine waters of the Bah'{i}a de Añasco near Mayag{u}ez, Puerto Rico. Trace metal concentrations in fine sediments deposited in the bay were measured to assess potential impact of the ocean outfall on the biota and habitats that include coral reefs. A Q-mode factor analysis of elemental compositions identified three sediment sources and their relative proportions in 51 core and surficial samples collected from the bay and within the coral reefs: (1) sediments discharged by the R'{i}o Grande de Añasco; (2) calcareous skeletal remains; and (3) sediments discharged by the R'{i}o Guanajibo. The nickel and chromium derived from laterite deposits provide a unique fingerprint for sediments discharged from the R'{i}o Guanajibo. Naturally occurring concentrations of these elements exceed Probable Effect Limits (PEL's: 42 mg/kg for nickel and 160 mg/kg for chromium) in sediments deposited near the river mouth. The detection of mercury at 1 mg/kg in one sample from a core recovered near the wastewater outfall was the only indication of a possible outfall source in the data set. The temporal and spatial variations in source fractions proved useful in determining relative frequencies of historic floods and steady-state circulation patterns off the west coast of Puerto Rico.

Sediment data for computations of deposition rates in the tidal Potomac system, Maryland and Virginia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glenn, J.L.; Martin, E.A.; Rice, C.A.

1986-01-01

Sixty-two cores ranging in length from 33 to 1,002 cm were collected from the tidal Potomac system and from selected tributaries downstream from the local head-of-tides between June 1978 and July 1981. Segments from selected depths below the sediment surface have been analyzed for a variety of constituents, including lead-210, trace metals, nutrients, and particle size. The core sites were positioned throughout the hydrologic divisions and geomorphic units of the tidal Potomac system and in water depths ranging from 1 to 30 cm. Alpha counting methods were used to determine the polonium-210 radioactivity and secular equilibrium was assumed between lead-210more » and polonium-210. The alpha decay of polonium-210 provides a measure of the lead-210 radioactivity of the lead-210 produced by in-situ decay of radium-226 in the sediment column and the lead-210 from external sources. Only the unsupported lead-210 was used in computations of the deposition rate. The background level of lead-210 in tidal Potomac system sediment cores usually is based on in-situ measurements of total lead-210 at depths below which no unsupported lead-210 is believed to be present, and the lead-210 concentrations are relatively constant. 6 refs., 3 figs., 1 tab.« less

Rare earth elements in core marine sediments of coastal East Malaysia by instrumental neutron activation analysis.

PubMed

Ashraf, Ahmadreza; Saion, Elias; Gharibshahi, Elham; Mohamed Kamari, Halimah; Chee Kong, Yap; Suhaimi Hamzah, Mohd; Suhaimi Elias, Md

2016-01-01

A study was carried out on the concentration of REEs (Dy, Sm, Eu,Yb, Lu, La and Ce) that are present in the core marine sediments of East Malaysia from three locations at South China Sea and one location each at Sulu Sea and Sulawesi Sea. The sediment samples were collected at a depth of between 49 and 109 m, dried, and crushed to powdery form. The entire core sediments prepared for Instrumental Neutron Activation Analysis (INAA) were weighted approximately 0.0500 g to 0.1000 g for short irradiation and 0.1500 g to 0.2000 g for long irradiation. The samples were irradiated with a thermal neutron flux of 4.0×10(12) cm(-2) s(-1) in a TRIGA Mark II research reactor operated at 750 kW. Blank samples and standard reference materials SL-1 were also irradiated for calibration and quality control purposes. It was found that the concentration of REEs varies in the range from 0.11 to 36.84 mg/kg. The chondrite-normalized REEs for different stations suggest that all the REEs are from similar origins. There was no significant REEs contamination as the enrichment factors normalized for Fe fall in the range of 0.42-2.82. Copyright © 2015 Elsevier Ltd. All rights reserved.

Estimating selenium removal by sedimentation from the Great Salt Lake, Utah

USGS Publications Warehouse

Oliver, W.; Fuller, C.; Naftz, D.L.; Johnson, W.P.; Diaz, X.

2009-01-01

The mass of Se deposited annually to sediment in the Great Salt Lake (GSL) was estimated to determine the significance of sedimentation as a permanent Se removal mechanism. Lake sediment cores were used to qualitatively delineate sedimentation regions (very high to very low), estimate mass accumulation rates (MARs) and determine sediment Se concentrations. Sedimentation regions were defined by comparison of isopach contours of Holocene sediment thicknesses to linear sedimentation rates determined via analysis of 210Pb, 226Ra, 7Be and 137Cs activity in 20 short cores (<5 cm), yielding quantifiable results in 13 cores. MARs were developed via analysis of the same radioisotopes in eight long cores (>10 cm). These MARs in the upper 1-2 cm of each long core ranged from 0.019 to 0.105 gsed/cm2/a. Surface sediment Se concentrations in the upper 1 or 2 cm of each long core ranged from 0.79 to 2.47 mg/kg. Representative MARs and Se concentrations were used to develop mean annual Se removal by sedimentation in the corresponding sedimentation region. The spatially integrated Se sedimentation rate was estimated to be 624 kg/a within a range of uncertainty between 285 and 960 kg/a. Comparison to annual Se loading and other potential removal processes suggests burial by sedimentation is not the primary removal process for Se from the GSL. ?? 2009 Elsevier Ltd.

Spatial Extent of Wave-Supported Fluid Mud on the Waipaoa Continental Margin

NASA Astrophysics Data System (ADS)

Hale, R. P.; Ogston, A. S.; Walsh, J. P.; Orpin, A. R.

2013-12-01

Data from acoustic and optical sensors provide a powerful tool to connect near-bed water-column processes with the deposits they generate. Ideally, the product of water-column and seabed interactions can then be applied more broadly to understand systems as a whole, in both space and time. Recent observational research has allowed for an improved understanding of shelf sediment-transport dynamics in many coastal systems, including the dynamic Waipaoa Sedimentary System (WSS), on the east coast of the north island of New Zealand. This narrow shelf (~20 km) on an active continental margin is subject to strong environmental forcings in the form of high waves (>5 m), strong currents (>50 cm/s), and frequent floods of the Waipaoa River, which delivers an average of 15 MT of sediment to Poverty Bay and the coastal environment each year. A year-long study of the WSS during 2010-2011 combined observational data from instrumented tripods at three locations on the continental shelf, with repeat sediment cores collected in four-month intervals, to identify and assess the mechanisms of cross- and off-shelf sediment transport. Observational data identified that cross-shelf sediment transport is stochastic, typically driven by high-wave events, with 40% of the net annual cross-shelf flux for one tripod location occurring during a single wave-supported fluid mud (WSFM) in July 2010. Fortunately, this event was recorded in the instrument data, and the resulting deposit was plainly visible in x-radiograph images. This particular WSFM was observed in x-radiographs collected as deep as ~50 m, and as far as ~28 km from the mouth of the Waipaoa River, and is more prevalent on the northern portion of the shelf. A critical water depth is not the only criteria for WSFM deposition, as some shallower areas on the southern shelf, which were subject to high bed stress, show no evidence of WSFM in this event, while cores collected in deeper areas (e.g. lower bed stress) on the northern shelf did observe WSFM. Interestingly, several cores on the southern shelf do appear to preserve evidence of previous wave-reworking of the seabed. It appears that the presence of a river plume and associated sediment, as well as the direction in which it is advected, are instrumental in WSFM generation.

Metal concentrations in surface sediments of Boston Harbor: Changes with time

USGS Publications Warehouse

Bothner, Michael H.; Buchholtz ten Brink, Marilyn R.; Manheim, F.T.

1998-01-01

The concentrations of metals in surface sediments of Boston Harbor have decreased during the period 1977–1993. This conclusion is supported by analysis of: (1) surface sediments collected at monitoring stations in the outer harbor between 1977 and 1993; (2) metal concentration profiles in sediment cores from depositional areas of the harbor; and (3) historical data from a contaminated-sediment database, which includes information on metal and organic contaminants and sediment texture. The background and matrix-corrected concentrations of lead (Pb) measured in the surficial layer (0–2 cm) of cores decreased by an average of 46%±12% among four locations in the outer harbor during the 16 y period. Chromium (Cr), copper (Cu), mercury (Hg), silver (Ag), and zinc (Zn) exhibited similar trends. Results from our sediment sampling are supported by historical data that were compiled from diverse sources into a regional sediment database. This sediment database contains approximately 3000 samples; of these, about 460 samples were collected and analyzed for Cu, Hg, or Zn and many other sediment parameters in Boston Harbor surface sediments between 1971–1993. The database indicates that the concentrations of these three metals also decreased with time in Boston’s Inner Harbor. The decreases in metal concentrations that are observed in more recent years parallel a general decrease in the flux of metals to the harbor, implemented by: (1) ending the sewage sludge discharge to the Harbor in December, 1991; (2) greater source reduction (e.g. recovery of silver from photographic processing) and closing or moving of industries; (3) improvements in wastewater handling and sewage treatment; and (4) diminishing use of lead in gasoline beginning about 1973. Despite the general decrease in metal concentrations in Boston Harbor surface sediments, the concentrations of Ag and Hg measured at some outer harbor stations in 1993 were still at, or above, the level associated with frequent adverse effects to marine organisms (guidelines are: Ag 3.7 μg g−1, Hg 1.17 μg g−1, from Long et al., 1995). Concentrations of the other metals listed were in the range considered to occasionally induce adverse biological effects.

Vertical distribution of potentially toxic elements in sediments impacted by intertidal geothermal hot springs (Bahia Concepcion, Gulf of California)

NASA Astrophysics Data System (ADS)

Leal-Acosta, M. L.; Shumilin, E.

2016-12-01

The intertidal geothermal hot springs (GHS) in Bahia Concepcion, Gulf of California are the source of potentially toxic elements to the adjacent marine environment surrounded by mangroves trees. The anoxic sediments enriched in organic carbon accumulate As, Hg and other heavy metals that can be bioavailable for the biota. To know the vertical distribution of these elements the geochemistry of a short sediment core was carried out. It was collected in June, 2010 in the mangrove area near to GHS (1 m) during a low tide, pushing manually a polypropylene tube into the sediments. The extracted sediment core was cut with plastic knife on 1 cm thick sub-samples, stored in plastic bags and transported on ice to the laboratory. The major and trace elements contents were determinate by ICP-MS after total digestion with stronger acids (HClO4-HNO3-HCl-HF). Certificate reference materials were used for the quality control of the method obtaining good recoveries for most of the elements (80-105%). The sediment core had high maximum contents of CaCO3 (70%) and total organic carbon (12%). The concentration of Hg along the core ranges from 650 to 74300 mg kg-1 and had more than three orders of magnitude above the reference values of 40 mg kg-1 for the Upper Continental Crust (UCC)1. In contrast, As ranges from 12 to 258 mg kg-1 resulting in more than one order of magnitude respect to UCC1 (1.7 mg kg-1). Similar pattern result for Mn, Cu, Pb, and Zn with the maximum values of 3200 mg kg-1, 42 mg kg-1, 12.4 mg kg-1, 71 mg kg-1 respectively that coincide with the maximum for As at the same core depth (4 cm). The Ca, Li, Co, Sb, U, and Mg also show high contents in comparison with the UCC1reference values. The maximum contents of Mo and Cd coincide with maximum concentration of sulfur (2%) at 6 to 8 cm. The enrichment factor calculated using Al as normalizing element showed Cd (7-280), As (26-329) and Hg (23-1196) as highly enriched mainly in the first centimeters of the sediment core. 1 Wedephol (1995)

Hominin Sites and Paleolakes Drilling Project. Chew Bahir, southern Ethiopia: How to get from three tonnes of sediment core to > 500 ka of continuous climate history?

NASA Astrophysics Data System (ADS)

Foerster, Verena; Asrat, Asfawossen; Cohen, Andrew S.; Gromig, Raphael; Günter, Christina; Junginger, Annett; Lamb, Henry F.; Schaebitz, Frank; Trauth, Martin H.

2016-04-01

In search of the environmental context of the evolution and dispersal of Homo sapiens and our close relatives within and beyond the African continent, the ICDP-funded Hominin Sites and Paleolakes Drilling Project (HSPDP) has recently cored five fluvio-lacustrine archives of climate change in East Africa. The sediment cores collected in Ethiopia and Kenya are expected to provide valuable insights into East African environmental variability during the last ~3.5 Ma. The tectonically-bound Chew Bahir basin in the southern Ethiopian rift is one of the five sites within HSPDP, located in close proximity to the Lower Omo River valley, the site of the oldest known fossils of anatomically modern humans. In late 2014, the two cores (279 and 266 m long respectively, HSPDP-CHB14-2A and 2B) were recovered, summing up to nearly three tonnes of mostly calcareous clays and silts. Deciphering an environmental record from multiple records, from the source region of modern humans could eventually allow us to reconstruct the pronounced variations of moisture availability during the transition into Middle Stone Age, and its implications for the origin and dispersal of Homo sapiens. Here we present the first results of our analysis of the Chew Bahir cores. Following the HSPDP protocols, the two parallel Chew Bahir sediment cores have been merged into one single, 280 m long and nearly continuous (>90%) composite core on the basis of a high resolution MSCL data set (e.g., magnetic susceptibility, gamma ray density, color intensity transects, core photographs). Based on the obvious cyclicities in the MSCL, correlated with orbital cycles, the time interval covered by our sediment archive of climate change is inferred to span the last 500-600 kyrs. Combining our first results from the long cores with the results from the accomplished pre-study of short cores taken in 2009/10 along a NW-SE transect across the basin (Foerster et al., 2012, Trauth et al., 2015), we have developed a hypothesis linking climate forcing and paleoenvironmental signal formation processes in the basin (e.g. the inverse correlation of the K flux with precipitation in the catchment), providing an important prerequisite for understanding the environmental record contained in the long sediment cores. The good recovery and anticipated high time resolution of the cores will give us a continuous record of environmental fluctuations on decadal to orbital timescales, which will allow us to test current hypotheses of the influence of climate on human evolution and dispersal.

Deposition behavior, risk assessment and source identification of heavy metals in reservoir sediments of Northeast China.

PubMed

Zhu, Lin; Liu, Jianwei; Xu, Shiguo; Xie, Zaigang

2017-08-01

Sediment cores from five reservoirs, located in the Liaoning and Jilin Provinces in Northeast China, were collected to investigate the accumulation and potential toxicity of heavy metals (Fe, Mn, Cu, Cd, Pb, Zn, and Cr) during a sampling campaign in February, 2015. The results showed that all the detected metals accumulated significantly, especially Cd, compared to their respective background values. Among these reservoirs, Biliuhe Reservoir had markedly increasing trends for organic matter and all the metals, among which Mn was elevated by 280% to 3411mg/kg in a core of only 18cm in depth. Xinlicheng Reservoir was characterized by heavy siltation and varying metal distribution due to its regular geometric features and pulsed flood events. The Enrichment factor (EF) and geo-accumulation index (I geo ) indicated Cd was strongly enriched by anthropogenic inputs, with the values of EF and I geo greater than 8 and 3, respectively. The toxicity assessment calculated using consensus-based sediment quality guidelines (SQGs) implied the whole cores of Tanghe and Dahuofang and the upper cores of Biliuhe, Xinlicheng and Fengman exhibited toxicity to sediment-dwelling organisms. Cr contributed more to Q m-PEC than the other heavy metals, because only Cr exceeded the probable effect concentration (PEC) despite its low enrichment. According to the results of correlation analysis (CA) and principal components analysis (PCA), mining industries and agricultural activities within the basin were the main anthropogenic pollution sources for these heavy metals. Copyright © 2017 Elsevier Inc. All rights reserved.

Hydrologic response of desert wetlands to Holocene climate change: preliminary results from the Soda Springs area, Mojave National Preserve, California

USGS Publications Warehouse

Pigati, Jeffrey S.; Reheis, Marith C.; McGeehin, John P.; Honke, Jeffrey S.; Bright, J.

2016-01-01

Desert wetlands are common features in arid environments and include a variety of hydrologic facies, including seeps, springs, marshes, wet meadows, ponds, and spring pools. Wet ground conditions and dense stands of vegetation in these settings combine to trap eolian, alluvial, and fluvial sediments that accumulate over time. The resulting deposits are collectively called ground-water discharge (GWD) deposits, and contain information on how small desert watersheds responded to climate change in the past. Most GWD studies in the southwestern U.S. have focused on the late Pleistocene because the Holocene was too dry to support the extensive wetland systems that were so pervasive just a few millennia earlier. Here we describe the results of a pilot project that involves coring extant wetlands and analyzing the sedimentology and microfauna of the recovered sediment to infer Holocene hydrologic conditions. In 2011, a series of cores were taken near wetlands situated along the western margin of the Soda Lake basin in the Mojave National Preserve of southern California. The core sediments appear to show that the wetlands responded to the relatively minor climate fluctuations that characterized the Holocene. However, our analysis was limited by relatively low sediment recovery (which only averaged 70-80%) and a general paucity of datable materials in the cores. Additional studies aimed at improving recovery and developing new techniques for concentrating plant microfossils (plant remains that are <150 m in diameter) for radiocarbon dating are ongoing.

Major and trace (including REEs) element stratigraphy in the first 90 m (around 1 Myr) of ANDRILL AND-1B drillcore.

NASA Astrophysics Data System (ADS)

Rugi, Francesco; Becagli, Silvia; Ghedini, Costanza; Severi, Mirko; Traversi, Rita; Udisti, Roberto; Monien, Donata; Kuhn, Gerhard; Giorgetti, Giovanna; Talarico, Franco

2010-05-01

An integrated system Inductively Coupled Plasma - Sector Field Mass Spectrometry (ICP-SFMS) and Inductively Coupled Plasma - Atomic Emission Spectrophotometry (ICP - AES) has been applied to quantify 39 major and trace elements (including Rare Earths Elements -REE) in Antarctic glaciomarine sediments collected in the framework of ANDRILL. This project aims to study the role of the Antarctic Continent within the global climatic system, by the recovery and analysis of two deep sediment cores (AND-1B, MIS and AND-2A, SMS), drilled close to the margin of the Ross Ice Shelf. The main goals of ANDRILL were to obtain a stratigraphic record that documents key steps in Antarctica's Cenozoic climatic and glacial history, and in the tectonic evolution of the Transantarctic Mountains and the West Antarctic rift System. In particular, the study of the geochemical composition of sediments along the two ANDRILL cores can provide information about the possible source of terrigenous material deposited over the drilling site (Harwood et al., 2006). Preliminary results with a spatial resolution of about 1 m for the geochemical composition of the interval 24.66- 85.24 m of depth of marine sediments from AND-1B core covering about the last 1 Ma, are here shown. The concentration ratio of each measured element with respect to Al concentration, used as terrigenous reference, was calculated in order to remove the possible effect on elemental concentrations of differences in average sediment grain-size along the core and possible dilution effects and point out specified metal enrichments. The presented data and depth profiles (e.g. Fe/Al, Mn/Al, Co/Al, Cr/Al, Eu/Al and Europium anomaly) relative to sediments deposited during the last Ma at the MIS site, show an evident discontinuity from samples collected above and below 58.4 m of depth, corresponding to about 0.45 Ma BP, following the latest AND-1B dating model (85.24 m of depth corresponding to about 0.988 Ma; the chronological datum of the sediments is developed from 40Ar/39Ar ages volcanic deposits, Naish et al. 2009). This difference of geochemical composition suggests different rock sources for the material deposited before and after about 0.45 Ma BP. In particular the geochemical composition of the upper sediments is similar to the one of McMurdo Volcanic Group (MVG) whereas the lower sediments are close to the compositions of samples collected in the Transantarctic Mountain (TAM). Such a different composition could be linked to the climatic discontinuity known as Mid-Brunhes Event (MBE), dated 430 Kyr BP, which marks the boundary between two different global climatic conditions, with the youngest part characterized by a larger temperature gap between short and warm interglacials and long and cold glacials, with respect to the oldest part. Bibliography: Harwood, D. et al. (2006), Deep drilling with the ANDRILL program in Antarctica, Sci. Drill., 3, 43-45. Naish T. et al. (2009), Obliquity-paced Pliocene West Antarctic ice sheet oscillations, Nature, 458, 322-328.

Major refit of R/V MARION DUFRESNE and giant sediment corer improvements

NASA Astrophysics Data System (ADS)

Leau, Hélène; Réaud, Yvan

2015-04-01

The french Research Vessel MARION DUFRESNE is equipped with a unique sediment coring facility, called CALYPSO, developed initially by Yvon BALUT at the French Polar Institute, Paul-Emile Victor (IPEV) that operates the vessel 217 days per year in all oceans. The CALYPSO sediment corer retrieves routinely 50 m long undisturbed sediment cores in any water depths, and presently holds the worldwide record of the longest core ever retrieved, that is 64.5 m. This vessel is then a fantastic opportunity for the paleoceanographic community to carry out expeditions at sea. Over the last 20 years, many international IMAGES coring expeditions were organized in all the ocean basins around the world on board the R/V MARION DUFRESNE. More than 1500 cores were retrieved, leading to major advances in the paleoceanography and paleoclimatology of the Late Quaternary. The vessel will celebrate her 20th anniversary in 2015 and will undergo a major refit on hull & machineries, public spaces, as well as scientific equipment. The coring capacity is currently being developed to further improve - The length of the retrievable core, with an objective of 75 m long core in routine - The quality of the sediment un-disturbance with a specially designed coring cable with controlled minimum elasticity - The safety of the operations at sea - The quality control of the operations with a suite of sensors and software allowing a detailed monitoring of the coring operation - The time requested for each operation - The environment data collection, in the same time as the coring operations The detailed description of the upgrades will be presented. They consist in a new suite of acoustic sensors that will be integrated on board the vessel during the 4 months ship yard stay from April to July 2015, amongst which a KONSBERG EM122 multibeam echo-sounder and a SBP 120-3 sub-bottom profiler, both mounted on a gondola fitted under the hull of the vessel. This equipment will allow the highest quality images of the seabed and upper sediment, allowing accurate survey of the coring targets. Scientific deck equipment, such as coring winch and associated A frame, hydrological winch and deployment system, will be upgraded, the coring operating equipment being brought up to 45 t SWL. The ship side will be modified to allow the deployment of 75 m long corer. Finally, the laboratories will be renovated and the main PC room will be redistributed in order to offer more space to the scientific party and secure a new IT dedicated room. The vessel will undergo a series of tests at sea before being available to the scientific community again from January 2016. As before her midlife refit, IPEV wishes to carry on training programs such as "University at Sea" and EGU supported "Teachers at sea" program in association with future paleoceanographic activities.

Initial Results on the Meteoritic Component of new Sediment Cores Containing Deposits of the Eltanin Impact Event

NASA Technical Reports Server (NTRS)

Kyte, Frank T.; Gersonde, Rainer; Kuhn, Gerhard

2002-01-01

The late Pliocene impact of the Eltanin asteroid is the only known asteroid impact in a deep- ocean (-5 km) basin . This was first discovered in 1981 as an Ir anomaly in sediment cores collected by the USNS Eltanin in 1965. In 1995, Polarstern expedition ANT XII/4 made the first geological survey of the suspected impact region. Three sediment cores sampled around the San Martin seamounts (approx. 57.5 S, 91 W) contained well-preserved impact deposits that include disturbed ocean sediments and meteoritic impact ejecta. The latter is composed of shock-melted asteroidal materials and unmelted meteorites. In 2001, the FS Polarstern returned to the impact area during expedition ANT XVIIU5a. At least 16 cores were recovered that contain ejecta deposits. These cores and geophysical data from the expedition can be used to map the effects of the impact over a region of about 80,000 square km. To date we have measured Ir concentrations in sediments from seven of the new cores and preliminary data should be available for a few more by the time of the meeting. Our initial interpretation of these data is that there is a region in the vicinity of the San Martin Seamounts comprising at least 20,000 square km in which the average amount of meteoritic material deposited was more than 1 g per square cm. This alone is enough material to support a 500 m asteroid. Beyond this is a region of about 60,000 square km, mostly to the north and west, where the amount of ejecta probably averages about 0.2 g per square cm. Another 400 km to the east, USNS Eltanin core E10-2 has about 0.05 g per square cm, so we know that ejecta probably occurs across more than a million square km of ocean floor. A key to future exploration of this impact is to find evidence of the ejecta at more sites distant from the seamounts. We currently have almost no data from regions to the west or south of the San Martin seamounts.

Modern foraminifera assemblages in the Amundsen Sea Embayment

NASA Astrophysics Data System (ADS)

Ewa Jernas, Patrycja; Kuhn, Gerhard; Hillenbrand, Claus-Dieter; Lander Rasmussen, Tine; Forwick, Matthias; Mackensen, Andreas; Schröder, Michael; Smith, James; Klages, Johann Philipp

2015-04-01

The West Antarctic Ice Sheet (WAIS) is considered the most unstable part of the Antarctic Ice Sheet. As the WAIS is mostly grounded below sea level, its stability is of great concern. A collapse of large parts of the WAIS would result in a significant global sea-level rise. At present, the WAIS shows dramatic ice loss in its Amundsen Sea sector, especially in Pine Island Bay. Pine Island Glacier (PIG) is characterised by fast flow, major thinning and rapid grounding-line retreat. Its mass los over recent decades is generally attributed to melting caused by the inflow of warm Circumpolar Deep Water (CDW). Future melting of PIG may result in a sea level tipping point, because it could trigger widespread collapse of the WAIS, especially when considering ongoing climate change. Our research project aims to establish proxies (integration of foraminifera, sediment properties and oceanographic data) for modern environmental conditions by analysing seafloor surface sediments along a transect from the glacier proximal settings to the middle-outer shelf in the eastern Amundsen Sea Embayment. These proxies will then be applied on sediment records spanning the Holocene back to the Last Glacial Maximum for reconstructing spatial and temporal variations of CDW upwelling and ice-ocean interactions during the past c. 23,000 years. We will present preliminary results from the analyses of ten short marine sediment cores (multi and box cores) collected during expeditions JR179 (2008) and ANT-XXVI/3 (2010) along a transect from inner Pine Island Bay to the middle-outer shelf part of the Abbot Palaeo-Ice Stream Trough at water depths ranging from 458 m (middle shelf) to 1444 m (inner shelf). The sediment cores are currently investigated for distribution patterns of planktonic and benthic foraminifera and grain-size distribution at 1 cm resolution. Core tops (0-10 cm) were stained with Rose Bengal for living benthic foraminifera investigations. The chronology of the cores will be based on 210Pb and calibrated 14C dates. First results reveal the presence of living benthic foraminifera in surface sediments of all investigated cores suggesting that modern seabed surfaces were recovered. Moreover, a core retrieved from a water depth of 793 m in the Abbot Palaeo-Ice Stream Trough shows particularly high abundances of planktonic foraminifera Neogloboquadrina pachyderma.

Recent Developments and Adaptations in Diamond Wireline Core Drilling Technology

NASA Astrophysics Data System (ADS)

Thomas, D. M.; Nielson, D. L.; Howell, B. B.; Pardey, M.

2001-05-01

Scientific drilling using diamond wireline technology is presently undergoing a significant expansion and extension of activities that has allowed us to recover geologic samples that have heretofore been technically or financially unattainable. Under the direction and management of DOSECC, a high-capacity hybrid core drilling system was designed and fabricated for the Hawaii Scientific Drilling Project (HSDP) in 1998. This system, the DOSECC Hybrid Coring System (DHCS), has the capacity to recover H-sized core from depths of more than 6 km. In 1999, the DHCS completed the first phase of the HSDP to a depth of 3100 m at a substantially lower cost per foot than any previous scientific borehole to comparable depths and, in the process, established a new depth record for recovery of H-sized wireline core. This system has been offered for use in the Unzen Scientific Drilling Project, the Chicxulub (impact crater) Scientific Drilling Project, and the Geysers Deep Geothermal Reservoir Project. More recently, DOSECC has developed a smaller barge-mounted wireline core drilling system, the GLAD800, that is capable of recovering P-sized sediment core to depths of up to 800 m. The GLAD800 has been successfully deployed on Great Salt Lake and Bear Lake in Utah and is presently being mobilized to Lake Titicaca in South America for an extensive core recovery effort there. The coring capabilities of the GLAD800 system will be available to the global lakes drilling community for acquisition of sediment cores from many of the world's deep lakes for use in calibrating and refining global climate models. Presently under development by DOSECC is a heave-compensation system that will allow us to expand the capabilities of the moderate depth coring system to allow us to collect sediment and bottom core from the shallow marine environment. The design and capabilities of these coring systems will be presented along with a discussion of their potential applications for addressing a range of earth sciences questions.

Radiocarbon chronology of Black Sea sediments

NASA Astrophysics Data System (ADS)

Jones, Glenn A.; Gagnon, Alan R.

1994-03-01

Accelerator Mass Spectrometer (AMS) radiocarbon analyses have been made on 102 samples from 12 sediment cores and 23 samples from two water column profiles. These materials, collected during the first leg of the 1988 joint U.S.-Turkish Black Sea Expedition, provide the most comprehensive radiocarbon chronology of Black Sea sediments yet attempted. Radiocarbon analyses from carefully collected box cores and a mollusc shell collected live in 1931 suggest the prebomb surface waters had a Δ 14C value of -55% (460 years) and that the maximum detrital correction for radiocarbon ages of Unit I sediments is 580 years for the organic carbon and 260 years for the carbonate fractions. Evidence does not support the 1430-2000 years pre-bomb surface water and/or detrital corrections argued for in past studies. The best estimates for the age of the beginning of the final invasion of the coccolithophore Emiliania huxleyi (Unit 1/2 boundary of Ross and DEGENS, 1974, The Black Sea—geology, chemistry and biology, pp. 183-199) and the age of the first invasion of E. huxeleyi (Unit I/II boundary of HAYet al., 1991, Deep-Sea Research, 38, S1211-S1235) are 1635 ± 60 and 2720 ± 160 years BP, respectively. Sapropel formation began at approximately 7540 ± 130 years BP at all depths in the basin, a pattern in disagreement with those predicted by existing time-evolution models of sapropel formation for this basin. Our data suggest that the oxic-anoxic interface has remained relatively stable throughout the Holocene, is controlled largely by the physical oceanography of the basin, and has not evolved as assumed by previous workers.

Interdisciplinary paleovegetation study in the Fernando de Noronha Island (Pernambuco State), northeastern Brazil.

PubMed

Pessenda, Luiz C R; Gouveia, Susy E M; Ledru, Marie-Pierre; Aravena, Ramon; Ricardi-Branco, Fresia S; Bendassolli, José A; Ribeiro, Adauto de S; Saia, Soraya E M G; Sifeddine, Abdelfettah; Menor, Eldemar de A; Oliveira, Sônia M B de; Cordeiro, Renato C; Freitas, Angela M de M; Boulet, René; Filizola, Heloisa F

2008-12-01

The aim of this research was to reconstruct vegetation changes (with climate inferences) that occurred during the Holocene in the Fernando de Noronha Island, Pernambuco State, northeastern Brazil. The research approach included the use of geochemical (mineralogy, elemental), carbon isotopes (delta13C, 14C) and pollen analyses in soil organic matter (SOM) and sediments collected in Lagoa da Viração and Manguezal do Sueste. The carbon isotopes data of SOM indicated that there was no significant vegetation changes during the last 7400 BP, suggesting that the climate was not the determinant factor for the vegetation dynamics. The pollen analysis of the sediment of a core collected in the Lagoa da Viração showed the absence of Quaternary material in the period between 720 BP and 90 BP. The mineralogical analysis of deeper layer showed the presence of diopside indicating this material was developed "in situ". Only in the shallow part of the core were found pollen of similar plant species of the modern vegetation. The geochemistry and isotope results, in association with the sediment type and pollen analyses of sediment samples of Manguezal do Sueste, indicated variations in the vegetation and in its location since the middle Holocene. Such variations can be associated with climatic events and sea level oscillations and also with anthropogenic events considering the last five hundred years.

Search for continuous paleoclimatic record in Holocene lacustrine sediments from Lake District, Chile (40°S)

NASA Astrophysics Data System (ADS)

Bertrand, S.; Fagel, N.

2003-04-01

Our aim is to reconstruct a continuous Holocene climatic evolution related to ENSO variability in southern Chile. We focus on the sedimentary infilling of two glacial lakes from the Lake District Area (38-40°S). The preliminar sedimentological analysis must allow to define the key-site and the best palaeoclimatic proxies. This area, at the foothill of the Cordillera de Los Andes, has been affected by an intense Quaternary volcanic activity and by several historical earthquakes (e.g., Valdivia 1960). After preliminary seismic investigation, four cores were recovered in two lakes selected at the two ends of a N-S transect. (1) Icalma lake (12 km2, 38°S) is located in the Cordillera de Los Andes at an elevation of 1150m and results of the infilling of a glacial umbilic. The two 8m sediment cores consist of an alternation of laminated silts and volcanic layers. The sedimentary record is strongly disturbed by numerous seismic or volcanic events. The cumulated volcanogenic-derived material represents up to 50 % of the core length. In particular, the cores record at -4.50m a pumice layer widespread in the watershed and dated at 2900 yr BP. One core contains pluricentrimetric layers of wood accumulation. They could be due to earthquake impact on the vegetational cover in the watershed. An ubiquitous 6cm-thick slump described at -40 cm may be related with the 1960 Valdivia earthquake. (2) On Puyehue lake (164 km2, 40°S, elevation 185 m), two cores (7 and 11m) have been collected in both underflow and interflow sites. The interflow site (PUII) shows a very well laminated sediment, with only small disturbances due to volcanic and seismic activities. This core will be the key-site for the paleoclimatic study. The second core (PUI) is very rich in organic matter. The sediment is strongly destratified by numerous gas bubbles (methane). These characteristics are due to the dense vegetational cover in the watershed and to the core location near the delta of the main river. This preliminary study emphasizes the influence of geodynamic conditions on sedimentology of lacustrine deposits in a geodynamically active region. The contribution of the punctual tectonic and volcanic-derived layers to sediment thickness must be taken into account before calculation of the age-depth model.

Susceptibility of synthetic long-chain alkylbenzenes to degradation in reducing marine sediments

USGS Publications Warehouse

Eganhouse, Robert P.; Pontolillo, James

2008-01-01

Long-chain alkylbenzenes (LCABs) synthesized for production of alkylbenzene sulfonate surfactants have been used as molecular markers of anthropogenic waste for 25 years. Synthetic LCABs comprise two classes, the tetrapropylene-based alkylbenzenes (TABs) and the linear alkylbenzenes (LABs). LABs supplanted TABs in the mid-1960s because of improved biodegradability of their sulfonated analogs. Use of LCABs for molecular stratigraphy depends on their preservation in sediments over decadal time scales. Most laboratory and field studies suggest that LABs degrade rapidly under aerobic conditions but are resistant to degradation when oxygen is absent. However, recent work indicates that LABs may not be as persistent under reducing conditions as previously thought. To assess the potential for degradation of LCABs in reducing sediments, box cores collected in 1992 and 2003 near a submarine wastewater outfall system were analyzed using gas chromatography/mass spectrometry. The TABs were effectively preserved; differences between whole-core inventories were within analytical error. By contrast, whole-core inventories of the LABs decreased by about 50-60% during the same time interval. Based on direct comparison of chemical inventories in coeval core sections, LAB transformation rates are estimated at 0.07 ±. 0.01 yr-1. These results indicate that caution should be exercised when using synthetic LCABs for reconstruction of depositional records.

Radionuclides (210Po and 210Pb) and Some Heavy Metals in Fish and Sediments in Lake Bafa, Turkey, and the Contribution of 210Po to the Radiation Dose.

PubMed

Manav, Ramazan; Uğur Görgün, Aysun; Filizok, Işık

2016-11-09

The pollution level of Lake Bafa was investigated by collecting fish samples { Dicentrarchus labrax (sea bass), Liza ramada (mullet) and Anguilla anguilla (eel)}, surface sediment, and core samples. In all these samples, 210 Po and 210 Pb concentrations were estimated, and total annual dose rates were obtained for each species. Some heavy metal (Cr, Ni, Pb, Cd, Mn, Fe, and Zn) concentration levels were obtained for the fish and a core sample. The sediment mass accumulation rate was found to be 3.27 g·m -2 ·day -1 (0.119 g·cm -2 ·y -1 ) from a core sample. The heavy metal concentrations in the vertical profile of samples from the core were also observed. The measured concentration of Zn, Pb, Cd, and Cr were between the ERL (effects range low) and ERM (effects range median) limits, while Ni concentrations were higher than the ERM limit. The observed concentrations of Cd, Pb, and Zn in fish samples did not exceed the limits in accordance with Turkish Food Regulations. Further, the maximum effective dose equivalent of 210 Po in the area was found to be 1.169 µSv·y -1 .

Benthic foraminiferal census data from Mobile Bay, Alabama--counts of surface samples and box cores

USGS Publications Warehouse

Richwine, Kathryn A.; Osterman, Lisa E.

2012-01-01

A study was undertaken in order to understand recent environmental change in Mobile Bay, Alabama. For this study a series of surface sediment and box core samples was collected. The surface benthic foraminiferal data provide the modern baseline conditions of the bay and can be used as a reference for changing paleoenvironmental parameters recorded in the box cores. The 14 sampling locations were chosen in the bay to cover the wide diversity of fluvial and marine-influenced environments on both sides of the shipping channel.

Recent paleorecords document rising mercury contamination in Lake Tanganyika

USGS Publications Warehouse

Conaway, C.H.; Swarzenski, P.W.; Cohen, A.S.

2012-01-01

Recent Lake Tanganyika Hg deposition records were derived using 14C and excess 210Pb geochronometers in sediment cores collected from two contrasting depositional environments: the Kalya Platform, located mid-lake and more removed from watershed impacts, and the Nyasanga/Kahama River delta region, located close to the lake's shoreline north of Kigoma. At the Kalya Platform area, pre-industrial Hg concentrations are 23??0.2ng/g, increasing to 74ng/g in modern surface sediment, and the Hg accumulation rate has increased from 1.0 to 7.2??g/m 2/a from pre-industrial to present, which overall represents a 6-fold increase in Hg concentration and accumulation. At the Nyasanga/Kahama delta region, pre-industrial Hg concentrations are 20??3ng/g, increasing to 46ng/g in surface sediment. Mercury accumulation rate has increased from 30 to 70??g/m 2/a at this site, representing a 2-3-fold increase in Hg concentration and accumulation. There is a lack of correlation between charcoal abundance and Hg accumulation rate in the sediment cores, demonstrating that local biomass burning has little relationship with the observed Hg concentration or Hg accumulation rates. Examined using a sediment focusing-corrected mass accumulation rate approach, the cores have similar anthropogenic atmospheric Hg deposition profiles, suggesting that after accounting for background sediment concentrations the source of accumulating Hg is predominantly atmospheric in origin. In summary, the data document an increase of Hg flux to the Lake Tanganyika ecosystem that is consistent with increasing watershed sediment delivery with background-level Hg contamination, and regional as well as global increases in atmospheric Hg deposition. ?? 2011.

Distribution and Rate of Methane Oxidation in Sediments of the Florida Everglades †

PubMed Central

King, Gary M.; Roslev, Peter; Skovgaard, Henrik

1990-01-01

Rates of methane emission from intact cores were measured during anoxic dark and oxic light and dark incubations. Rates of methane oxidation were calculated on the basis of oxic incubations by using the anoxic emissions as an estimate of the maximum potential flux. This technique indicated that methane oxidation consumed up to 91% of the maximum potential flux in peat sediments but that oxidation was negligible in marl sediments. Oxygen microprofiles determined for intact cores were comparable to profiles measured in situ. Thus, the laboratory incubations appeared to provide a reasonable approximation of in situ activities. This was further supported by the agreement between measured methane fluxes and fluxes predicted on the basis of methane profiles determined by in situ sampling of pore water. Methane emissions from peat sediments, oxygen concentrations and penetration depths, and methane concentration profiles were all sensitive to light-dark shifts as determined by a combination of field and laboratory analyses. Methane emissions were lower and oxygen concentrations and penetration depths were higher under illuminated than under dark conditions; the profiles of methane concentration changed in correspondence to the changes in oxygen profiles, but the estimated flux of methane into the oxic zone changed negligibly. Sediment-free, root-associated methane oxidation showed a pattern similar to that for methane oxidation in the core analyses: no oxidation was detected for roots growing in marl sediment, even for roots of Cladium jamaicense, which had the highest activity for samples from peat sediments. The magnitude of the root-associated oxidation rates indicated that belowground plant surfaces may not markedly increase the total capacity for methane consumption. However, the data collectively support the notion that the distribution and activity of methane oxidation have a major impact on the magnitude of atmospheric fluxes from the Everglades. PMID:16348299

Methane Metabolizing Microbial Communities in the Cold Seep Areas in the Northern Continental Shelf of South China Sea

NASA Astrophysics Data System (ADS)

Wang, F.; Liang, Q.

2016-12-01

Marine sediment contains large amount of methane, estimated approximately 500-2500 gigatonnes of dissolved and hydrated methane carbon stored therein, mainly in continental margins. In localized specific areas named cold seeps, hydrocarbon (mainly methane) containing fluids rise to the seafloor, and support oases of ecosystem composed of various microorganisms and faunal assemblages. South China Sea (SCS) is surrounded by passive continental margins in the west and north and convergent margins in the south and east. Thick organic-rich sediments have accumulated in the SCS since the late Mesozoic, which are continuing sources to form gas hydrates in the sediments of SCS. Here, Microbial ecosystems, particularly those involved in methane transformations were investigated in the cold seep areas (Qiongdongnan, Shenhu, and Dongsha) in the northern continental shelf of SCS. Multiple interdisciplinary analytic tools such as stable isotope probing, geochemical analysis, and molecular ecology, were applied for a comprehensive understanding of the microbe mediated methane transformation in this project. A variety of sediments cores have been collected, the geochemical profiles and the associated microbial distribution along the sediment cores were recorded. The major microbial groups involved in the methane transformation in these sediment cores were revealed, known methane producing and oxidizing archaea including Methanosarcinales, anaerobic methane oxidizing groups ANME-1, ANME-2 and their niche preference in the SCS sediments were found. In-depth comparative analysis revealed the presence of SCS-specific archaeal subtypes which probably reflected the evolution and adaptation of these methane metabolizing microbes to the SCS environmental conditions. Our work represents the first comprehensive analysis of the methane metabolizing microbial communities in the cold seep areas along the northern continental shelf of South China Sea, would provide new insight into the mechanisms of methane biotransformation.

Vertical distribution of dehalogenating bacteria in mangrove sediment and their potential to remove polybrominated diphenyl ether contamination.

PubMed

Pan, Ying; Chen, Juan; Zhou, Haichao; Farzana, Shazia; Tam, Nora F Y

2017-11-30

The removal and degradation of polybrominated diphenyl ethers (PBDEs) in sediments are not clear. The vertical distribution of total and dehalogenating bacteria in sediment cores collected from a typical mangrove swamp in South China and their intrinsic degradation potential were investigated. These bacterial groups had the highest abundances in surface sediments (0-5cm). A 5-months microcosm experiment also showed that surface sediments had the highest rate to remove BDE-47 than deeper sediments (5-30cm) under anaerobic condition. The deeper sediments, being more anaerobic, had lower population of dehalogenating bacteria leading to a weaker BDE-47 removal potential than surface sediments. Stepwise multiple regression analysis indicated that Dehalococcoides spp. were the most important dehalogenating bacteria affecting the anaerobic removal of BDE-47 in mangrove sediments. This is the first study reporting that mangrove sediments harbored diverse groups of dehalogenating bacteria and had intrinsic potential to remove PBDE contamination. Copyright © 2016 Elsevier Ltd. All rights reserved.

DDTs and HCHs in sediment cores from the coastal East China Sea.

PubMed

Lin, Tian; Nizzetto, Luca; Guo, Zhigang; Li, Yuanyuan; Li, Jun; Zhang, Gan

2016-01-01

Four sediment cores were collected along the Yangtze-derived sediment transport pathway in the inner shelf of the East China Sea (ECS) for OCP analysis. The sediment records of HCHs and DDTs in estuarine environment reflected remobilization of chemicals from enhanced soil erosion associated to extreme flood events or large scale land use transformation. The sediment records in the open sea, instead, reflected long-term historical trends of OCP application in the source region. Unlike the so-called mud wedge distribution of sediment, inventories of HCHs and DDTs slightly increased from the mouth of Yangtze River alongshore toward south, suggesting the sediment deposition rate was one of factors on the exposure of chemicals within the inner shelf of the ECS. Re-suspension and transport of the Yangtze-derived sediment and consequent fractionation in grain size and TOC were also responsible for the spatial variation of inventories of catchment derived OCPs in a major repository area of the Yangtze suspended sediment. The total burdens of HCHs and DDTs in the inner shelf of the ECS were 35tons and 110tons, respectively. After 1983 (year of the official ban in China), those values were 13tons and 50tons, respectively. It appears that the Yangtze still delivers relatively high inputs of DDTs more than 30years after the official ban. High proportions of DDD+DDE and β-HCH suggested those OCPs mainly originated from historical usage in the catchment recent years. Copyright © 2015 Elsevier B.V. All rights reserved.

The origin of shallow lakes in the Khorezm Province, Uzbekistan, and the history of pesticide use around these lakes

USGS Publications Warehouse

Rosen, Michael R.; Crootof, Arica; Reidy, Liam; Saito, Laurel; Nishonov, Bakhriddin; Scott, Julian A.

2018-01-01

The economy of the Khorezm Province in Uzbekistan relies on the large-scale agricultural production of cotton. To sustain their staple crop, water from the Amu Darya is diverted for irrigation through canal systems constructed during the early to mid-twentieth century when this region was part of the Soviet Union. These diversions severely reduce river flow to the Aral Sea. The Province has >400 small shallow (<3 m deep) lakes that may have originated because of this intensive irrigation. Sediment cores were collected from 12 lakes to elucidate their origin because this knowledge is critical to understanding water use in Khorezm. Core chronological data indicate that the majority of the lakes investigated are less than 150 years old, which supports a recent origin of the lakes. The thickness of lacustrine sediments in the cores analyzed ranged from 20 to 60 cm in all but two of the lakes, indicating a relatively slow sedimentation rate and a relatively short-term history for the lakes. Hydrologic changes in the lakes are evident from loss on ignition and pollen analyses of a subset of the lake cores. The data indicate that the lakes have transitioned from a dry, saline, arid landscape during pre-lake conditions (low organic carbon content) and low pollen concentrations (in the basal sediments) to the current freshwater lakes (high organic content), with abundant freshwater pollen taxa over the last 50–70 years. Sediments at the base of the cores contain pollen taxa dominated by Chenopodiaceae and Tamarix, indicating that the vegetation growing nearby was tolerant to arid saline conditions. The near surface sediments of the cores are dominated by Typha/Sparganium, which indicate freshwater conditions. Increases in pollen of weeds and crop plants indicate an intensification of agricultural activities since the 1950s in the watersheds of the lakes analyzed. Pesticide profiles of DDT (dichlorodiphenyltrichloroethane) and its degradates and γ-HCH (gamma-hexachlorocyclohexane), which were used during the Soviet era, show peak concentrations in the top 10 cm of some of the cores, where estimated ages of the sediments (1950–1990) are associated with peak pesticide use during the Soviet era. These data indicate that the lakes are relatively young (mostly <150 years old) and that without irrigation and canal inputs from the Amu Darya, the lakes would not exist as freshwater lakes.

What Controls Sediment Retention in an Emerging Delta?

NASA Astrophysics Data System (ADS)

Keogh, M.; Kolker, A.

2016-12-01

What controls sediment retention in an emerging delta? Here, we examine the effects of river discharge and flow velocity on sediment retention rate, using a developing crevasse splay in the Lower Mississippi Delta as a study location. With a controlled discharge that ranges from 28 to 280 m3/s, Davis Pond Freshwater Diversion connects the Mississippi River to the adjacent wetland, allowing river water, sediment, and nutrients to flow into the marsh. Although Davis Pond was primarily designed to regulate salinity within Barataria Basin rather than to build land, a new crevasse splay has recently emerged at the mouth of the diversion's outfall channel. Short (5 cm) sediment cores were collected at 22 locations around the Davis Pond receiving basin in spring 2015, fall 2015, and spring 2016. All cores were analyzed for sediment geotechnical parameters including organic content, bulk density, and grain size. Sediment input into the receiving basin was calculated using a ratings curve. Activity of the radioisotope beryllium-7 was used to calculate rates of sediment accumulation and retention. We find that while sediment input is greater during high flow, rate of retention is greater during low flow. This is likely due to the increase in flow velocity that accompanies high discharge, which retains sediment in suspension and leads to more throughput of material. Furthermore, the diversion operation regime of sustained low flow punctuated by short-duration high discharge events has increased soil bulk density, mineral sediment accumulation, and marsh platform elevation. River diversions such as Davis Pond mimic the land-building processes of natural crevasse splays and provide a promising method to restore deltaic wetlands worldwide.

Sources of polychlorinated biphenyls to Devils Swamp Lake near Baton Rouge, Louisiana

USGS Publications Warehouse

Van Metre, Peter C.; Wilson, Jennifer T.; Kimball, Briant A.

2006-01-01

Devils Swamp Lake near Baton Rouge, Louisiana, created in 1973 by dredging in Devils Swamp along the Mississippi River, is contaminated with polychlorinated biphenyls (PCBs) from historical industrial discharges. This study involved the investigation of the occurrence, distribution, and sources of PCBs in the lake, including the possible historical contribution of PCBs from a hazardous-chemical disposal facility by way of a wastewater drainage ditch that was used from 1971 to 1993. Six bed sediment cores from the lake and three bed sediment grab samples from the drainage ditch were collected; 61 subsamples from selected intervals in five of the six cores and the three grab samples from the ditch were analyzed for PCBs using an immunoassay screening method. Sixteen of the core subsamples and one ditch sample were analyzed for organochlorine pesticides, PCBs, polycyclic aromatic hydrocarbons (PAHs) (15 samples), and major and trace elements. PCB congener profiles and a factor analysis of congener composition indicate that PCBs in sediment from the drainage ditch and in lake sediment deposited near the canal since the mid-1980s are similar, which indicates the disposal facility, by way of the wastewater drainage ditch, is the source of the PCBs. Sediment from several hundred meters down the lake to the west, near where Bayou Baton Rouge enters the lake, had a different PCB composition and in a sample deposited in the early 1980s, a much higher concentration, indicating a second source of PCBs in the watershed of Bayou Baton Rouge. Large differences in PAHs and metals between sediment near the ditch and sediment near Bayou Baton Rouge support this conclusion. The identity of the Bayou Baton Rouge source(s) cannot be established using available data. The short duration and relatively high concentrations of PCBs from the bayou source indicate either a spill or a flood-related release-there was a large flood on the Mississippi River in 1983. Older (deeper) samples from cores near the drainage ditch (dated as deposited before the mid-1980s) had PCB compositions that indicate a mixture of sources (Bayou Baton Rouge and the drainage ditch). Elevated PCB concentrations in sediment from the drainage ditch and cores from near the mouth of the ditch in recent (post-2000) samples indicate that some PCB inputs from the ditch might still be occurring.

Completion summary for boreholes USGS 140 and USGS 141 near the Advanced Test Reactor Complex, Idaho National Laboratory, Idaho

USGS Publications Warehouse

Twining, Brian V.; Bartholomay, Roy C.; Hodges, Mary K.V.

2014-01-01

In 2013, the U.S. Geological Survey, in cooperation with the U.S. Department of Energy, drilled and constructed boreholes USGS 140 and USGS 141 for stratigraphic framework analyses and long-term groundwater monitoring of the eastern Snake River Plain aquifer at the Idaho National Laboratory in southeast Idaho. Borehole USGS 140 initially was cored to collect continuous geologic data, and then re-drilled to complete construction as a monitor well. Borehole USGS 141 was drilled and constructed as a monitor well without coring. Boreholes USGS 140 and USGS 141 are separated by about 375 feet (ft) and have similar geologic layers and hydrologic characteristics based on geophysical and aquifer test data collected. The final construction for boreholes USGS 140 and USGS 141 required 6-inch (in.) diameter carbon-steel well casing and 5-in. diameter stainless-steel well screen; the screened monitoring interval was completed about 50 ft into the eastern Snake River Plain aquifer, between 496 and 546 ft below land surface (BLS) at both sites. Following construction and data collection, dedicated pumps and water-level access lines were placed to allow for aquifer testing, for collecting periodic water samples, and for measuring water levels. Borehole USGS 140 was cored continuously, starting from land surface to a depth of 543 ft BLS. Excluding surface sediment, recovery of basalt and sediment core at borehole USGS 140 was about 98 and 65 percent, respectively. Based on visual inspection of core and geophysical data, about 32 basalt flows and 4 sediment layers were collected from borehole USGS 140 between 34 and 543 ft BLS. Basalt texture for borehole USGS 140 generally was described as aphanitic, phaneritic, and porphyritic; rubble zones and flow mold structure also were described in recovered core material. Sediment layers, starting near 163 ft BLS, generally were composed of fine-grained sand and silt with a lesser amount of clay; however, between 223 and 228 ft BLS, silt with gravel was described. Basalt flows generally ranged in thickness from 3 to 76 ft (average of 14 ft) and varied from highly fractured to dense with high to low vesiculation. Geophysical and borehole video logs were collected during certain stages of the drilling and construction process at boreholes USGS 140 and USGS 141. Geophysical logs were examined synergistically with the core material for borehole USGS 140; additionally, geophysical data were examined to confirm geologic and hydrologic similarities between boreholes USGS 140 and USGS 141 because core was not collected for borehole USGS 141. Geophysical data suggest the occurrence of fractured and (or) vesiculated basalt, dense basalt, and sediment layering in both the saturated and unsaturated zones in borehole USGS 141. Omni-directional density measurements were used to assess the completeness of the grout annular seal behind 6-in. diameter well casing. Furthermore, gyroscopic deviation measurements were used to measure horizontal and vertical displacement at all depths in boreholes USGS 140 and USGS 141. Single-well aquifer tests were done following construction at wells USGS 140 and USGS 141 and data examined after the tests were used to provide estimates of specific-capacity, transmissivity, and hydraulic conductivity. The specific capacity, transmissivity, and hydraulic conductivity for well USGS 140 were estimated at 2,370 gallons per minute per foot [(gal/min)/ft)], 4.06 × 105 feet squared per day (ft2/d), and 740 feet per day (ft/d), respectively. The specific capacity, transmissivity, and hydraulic conductivity for well USGS 141 were estimated at 470 (gal/min)/ft, 5.95 × 104 ft2/d, and 110 ft/d, respectively. Measured flow rates remained relatively constant in well USGS 140 with averages of 23.9 and 23.7 gal/min during the first and second aquifer tests, respectively, and in well USGS 141 with an average of 23.4 gal/min. Water samples were analyzed for cations, anions, metals, nutrients, volatile organic compounds, stable isotopes, and radionuclides. Water samples from both wells indicated that concentrations of tritium, sulfate, and chromium were affected by wastewater disposal practices at the Advanced Test Reactor Complex. Most constituents in water from wells USGS 140 and USGS 141 had concentrations similar to concentrations in well USGS 136, which is upgradient from wells USGS 140 and USGS 141.

Perfluoroalkyl acids in the Canadian environment: multi-media assessment of current status and trends.

PubMed

Gewurtz, Sarah B; Backus, Sean M; De Silva, Amila O; Ahrens, Lutz; Armellin, Alain; Evans, Marlene; Fraser, Susan; Gledhill, Melissa; Guerra, Paula; Harner, Tom; Helm, Paul A; Hung, Hayley; Khera, Nav; Kim, Min Gu; King, Martha; Lee, Sum Chi; Letcher, Robert J; Martin, Pamela; Marvin, Chris; McGoldrick, Daryl J; Myers, Anne L; Pelletier, Magella; Pomeroy, Joe; Reiner, Eric J; Rondeau, Myriam; Sauve, Marie-Claude; Sekela, Mark; Shoeib, Mahiba; Smith, Daniel W; Smyth, Shirley Anne; Struger, John; Spry, Doug; Syrgiannis, Jim; Waltho, Jasmine

2013-09-01

In Canada, perfluoroalkyl acids (PFAAs) have been the focus of several monitoring programs and research and surveillance studies. Here, we integrate recent data and perform a multi-media assessment to examine the current status and ongoing trends of PFAAs in Canada. Concentrations of perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA), and other long-chain perfluorocarboxylates (PFCAs) in air, water, sediment, fish, and birds across Canada are generally related to urbanization, with elevated concentrations observed around cities, especially in southern Ontario. PFOS levels in water, fish tissue, and bird eggs were below their respective Draft Federal Environmental Quality Guidelines, suggesting there is low potential for adverse effects to the environment/organisms examined. However, PFOS in fish and bird eggs tended to exceed guidelines for the protection of mammalian and avian consumers, suggesting a potential risk to their wildlife predators, although wildlife population health assessments are needed to determine whether negative impacts are actually occurring. Long-term temporal trends of PFOS in suspended sediment, sediment cores, Lake Trout (Salvelinus namaycush), and Herring Gull (Larus argentatus) eggs collected from Lake Ontario increased consistently from the start of data collection until the 1990s. However, after this time, the trends varied by media, with concentrations stabilizing in Lake Trout and Herring Gull eggs, and decreasing and increasing in suspended sediment and the sediment cores, respectively. For PFCAs, concentrations in suspended sediment, sediment cores, and Herring Gulls generally increased from the start of data collection until present and concentrations in Lake Trout increased until the late 1990s and subsequently stabilized. A multimedia comparison of PFAA profiles provided evidence that unexpected patterns in biota of some of the lakes were due to unique source patterns rather than internal lake processes. High concentrations of PFAAs in the leachate and air of landfill sites, in the wastewater influent/effluent, biosolids, and air at wastewater treatment plants, and in indoor air and dust highlight the waste sector and current-use products (used primarily indoors) as ongoing sources of PFAAs to the Canadian environment. The results of this study demonstrate the utility of integrating data from different media. Simultaneous evaluation of spatial and temporal trends in multiple media allows inferences that would be impossible with data on only one medium. As such, more co-ordination among monitoring sites for different media is suggested for future sampling, especially at the northern sites. We emphasize the importance of continued monitoring of multiple-media for determining future responses of environmental PFAA concentrations to voluntary and regulatory actions. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

Evaluation of surficial sediment toxicity and sediment physico-chemical characteristics of representative sites in the Lagoon of Venice (Italy)

NASA Astrophysics Data System (ADS)

Losso, C.; Arizzi Novelli, A.; Picone, M.; Marchetto, D.; Pessa, G.; Molinaroli, E.; Ghetti, P. F.; Volpi Ghirardini, A.

2004-11-01

Toxic hazard in sites with varying types and levels of contamination in the Lagoon of Venice was estimated by means of toxicity bioassays based on the early life-stages of the autochthonous sea urchin Paracentrotus lividus. Elutriate was chosen as the test matrix, due to its ability to highlight potential toxic effects towards sensitive biological components of the water column caused by sediment resuspension phenomena affecting the Lagoon. Surficial sediments (core-top 5 cm deep), directly influenced by resuspension/redeposition processes, and core sediments (core 20 cm deep), recording time-mediated contamination, were sampled in some sites located in the lagoonal area most greatly influenced by anthropogenic activities. Particle size, organic matter and water content were also analysed. In two sites, the results of physical parameters showed that the core-top sediments were coarser than the 20-cm core sediments. Sperm cell toxicity test results showed the negligible acute toxicity of elutriates from all investigated sites. The embryo toxicity test demonstrated a short-term chronic toxicity gradient for elutriates from the 20-cm core sediments, in general agreement both with the expected contamination gradient and with results of the Microtox® solid-phase test. Elutriates of the core-top 5-cm sediments revealed a totally inverted gradient, in comparison with that for the 20-cm core sediments, and the presence of a "hot spot" of contamination in the site chosen as a possible reference. Investigations on ammonia and sulphides as possible confounding factors excluded their contribution to this "hot spot". Integrated physico-chemical and toxicity results on sediments at various depths demonstrated the presence of disturbed sediments in the central basin of the Lagoon of Venice.

Vertical profile, contamination assessment, and source apportionment of heavy metals in sediment cores of Kaohsiung Harbor, Taiwan.

PubMed

Chen, Chih-Feng; Ju, Yun-Ru; Chen, Chiu-Wen; Dong, Cheng-Di

2016-12-01

Six sediment cores collected at the Kaohsiung Harbor of Taiwan were analyzed to evaluate their vertical profiles, enrichments, accumulations, and source apportionments of heavy metals. This was performed to investigate any potential ecological risks posed by heavy metals. Results indicated that the mean heavy metal content (mg kg -1 ) in the six sediment cores was as follows: Hg (0.4-6.4), Cd (<0.05-2.4), Cr (18-820), Cu (16-760), Pb (31-140), and Zn (76-1900). The patterns of heavy metal content in the sediment cores differed substantially among the four river mouths. However, the vertical profiles of metals were relatively stable, indicating that wastewater has the constant characteristics and has been discharged into the rivers for a long period of time. Results of pollution assessment of enrichment factor, geo-accumulation index, and pollution load index revealed that river mouths experience severe enrichment, strong accumulation, and high contamination from the primary heavy metals. It was not consistent in the assessment results of mean effect range median quotient, potential ecological risk index, and total toxic unit method. Potential ecological risks caused by Hg in the sediments at Canon River and Love River mouths on aquatic organisms were extremely high. The estimates derived from the receptor modeling of multiple linear regression of the absolute principal component scores indicated that the contributions of the composite heavy metals derived from the Canon River and the Love River on the potential toxicity and risks to the water environment of Kaohsiung Harbor were highest, followed by those derived from Salt River and Jen-Gen River. Copyright © 2016 Elsevier Ltd. All rights reserved.

Assessment of gamma-emitting radionuclides in sediment cores from the Gulf of Aqaba, Red Sea.

PubMed

Ababneh, Zaid Q; Al-Omari, Husam; Rasheed, Mohamad; Al-Najjar, Tariq; Ababneh, Anas M

2010-10-01

The Gulf of Aqaba is the only seaport in Jordan which currently has intense activities such as industrial development, phosphate ore exportation, oil importation, shipping, commercial and sport fishing. Most of these activities, especially the phosphate ore exportation, could cause serious radiological effects to the marine environment. Thus, it is essential to investigate the level of the radioactivity concentrations to establish a baseline database, which is not available yet in the Gulf of Aqaba. Radioactivity concentrations of gamma-emitting radionuclides in core and beach sediments of the Gulf of Aqaba were investigated. Core sediments were collected from five representative locations for three different water column depths (5, 15 and 35 m). The results showed that the activity concentrations of 238U, 235U and 226Ra for both seafloor and beach sediments from the phosphate loading berth (PLB) location to be higher than those from other investigated locations and more than twice as high as the worldwide average; the 238U activity concentration was found to vary from 57 to 677 Bq kg(-1). The results also showed that there is little variation of radioactivity concentrations within the core length of 15 cm. The calculated mean values of the radium equivalent activity Ra(eq), the external hazard index, H(ex), the absorbed dose rate and the annual effective dose for the beach sediment in PLB location were 626 Bq kg(-1), 1.69, 263 nGy h(-1) and 614 µSv y(-1), respectively. These values are much higher than the recommended limits that impose potential health risks to the workers in this location. As for other studied locations, the corresponding values were far below the maximum recommended limit and lies within the worldwide range.

The Varved Sediments of Lake Bosumtwi, Ghana and Implications for a new Chronology of West African Hydrologic Change During the Late Quaternary

NASA Astrophysics Data System (ADS)

Wheeler, C. W.; Overpeck, J. T.; Beck, J. W.; Arko, J.; Sharp, W. E.

2002-12-01

Lake Bosumtwi is a small (8-km diameter), deep (78-m) crater lake in the lowland forest of southern Ghana (West Africa) that offers tremendous potential for high-resolution environmental reconstruction. Lying in the path of the seasonal Intertropical Convergence Zone (ITCZ) monsoonal precipitation procession, as well as the dry Harmattan winds of the Sahel in winter, this lake is uniquely located to provide potential proxy records of these dominate climatic phenomena effecting West Africa's hydrologic cycle. The lake exhibits excellent sediment preservation, with finely laminated sediments through most of the ca. 24,000 years of core material recovered thus far. We present a detailed chronological analysis of the uppermost 1.1 meters of laminated sediment, obtained via a recently collected suite of freeze- and piston-cores. Utilizing digital images and petrographic thin-section transects of six freeze-cores and two piston cores, we identified 400 diagnostic marker laminations common among the cores, thus enabling cross correlation of the cores to a sub-centimeter scale. The marker laminations also serve as anchor points for counts of organic-rich fine-laminations that were hypothesized to be annual. Excellent agreement between our lamination counts and independent radiometric sediment age models (lead-210 and bomb radiocarbon) verify that these counted laminations are in fact annual (i.e. varves). Thus, we are able to present an annual chronology for the last 800 years of sedimentation (prior to 2000 AD)ñ ~4%. Though anthroprogenic changes have probably effected the local environment within the last 100 years, as we interpret anomalous increases in %organic carbon, %inorganic carbon and %nitrogen to indicate, the varve appearance does not seem to change across the 1.1 m section analyzed. Pre-nuclear weapon testing radiocarbon values, derived from bulk organic carbon, were examined in relation to the varve and lead-210 age-models to assess radiocarbon age offset due to reservoir effects and the redeposition of old-carbon; the data suggest that anomalously old radiocarbon ages ranging from ~430 to 3000 years are possible. The size of the radiocarbon bias may vary with lake status, indicating the role of old-carbon redeposition from ancient lake sediments currently at shallow depths or above current lake level in the crater catchment. Our study shows that 1) varves have excellent potential for creating a high-resolution chronology for Lake Bosumtwi, and 2) caution must be taken in using radiocarbon results to date the sediments of Lake Bosumtwi

The top of the Olduvai subchron in a high-resolution magnetostratigraphy from the West Turkana core WTK13, Hominin Sites and Paleolakes Drilling Project (HSPDP)

NASA Astrophysics Data System (ADS)

Sier, Mark; Langereis, Cor; Dupont-Nivet, Guillaume; Feibel, Craig; Jordeens, Jose; van der Lubbe, Jeroen; Beck, Catherine; Olago, Daniel; Cohen, Andrew

2017-04-01

One of the major challenges in understanding the evolution of our own species is identifying the role climate change has played in the evolution of earlier hominin species. To clarify the influence of climate, we need long and continuous high-resolution paleoclimate records, preferably obtained from hominin-bearing sediments, that are well-dated by tephro- and magnetostratigraphy and other methods. This is hindered, however, by the fact that fossil-bearing sediments are often discontinuous, and subject to weathering, which may lead to oxidation and remagnetization. To obtain fresh, unweathered sediments, the Hominin Sites and Paleolakes Drilling Project (HSPDP) collected a 216- meter core (WTK13) in 2013 from deposits of Early Pleistocene paleolake Lorenyang in the western Turkana Basin (Kenya). Here, we present the magnetostratigraphy of the core. Rock magnetic analyses reveal the presence of iron sulphides carrying the remanent magnetizations. To recover polarity orientation from the near-equatorial WTK13 core drilled at 5°N, we developed and successfully applied two independent drill-core reorientation methods taking advantage of (1) the sedimentary fabric as expressed in the Anisotropy of Magnetic Susceptibility (AMS) and (2) the occurrence of a viscous component oriented in the present day field. The reoriented directions reveal a normal to reversed polarity reversal identified as the top of the Olduvai subchron. From this excellent record, we find no evidence for the 'Vrica subchron' previously reported in the area. We suggest that outcrop-based interpretations supporting the presence of the Vrica subchron have been affected by the oxidation of iron sulphides initially present in the sediments as evident in the core record, and by subsequent remagnetization. Based on our new high-resolution magnetostratigraphy and stratigraphic markers, we provide constraints for an initial age model of the WTK13 core. We discuss the implications of the observed geomagnetic record for human evolution studies.

Third-generation site characterization: Cryogenic core collection, nuclear magnetic resonance, and electrical resistivity

NASA Astrophysics Data System (ADS)

Kiaalhosseini, Saeed

In modern contaminant hydrology, management of contaminated sites requires a holistic characterization of subsurface conditions. Delineation of contaminant distribution in all phases (i.e., aqueous, non-aqueous liquid, sorbed, and gas), as well as associated biogeochemical processes in a complex heterogeneous subsurface, is central to selecting effective remedies. Arguably, a factor contributing to the lack of success of managing contaminated sites effectively has been the limitations of site characterization methods that rely on monitoring wells and grab sediment samples. The overarching objective of this research is to advance a set of third-generation (3G) site characterization methods to overcome shortcomings of current site characterization techniques. 3G methods include 1) cryogenic core collection (C3) from unconsolidated geological subsurface to improve recovery of sediments and preserving key attributes, 2) high-throughput analysis (HTA) of frozen core in the laboratory to provide high-resolution, depth discrete data of subsurface conditions and processes, 3) resolution of non-aqueous phase liquid (NAPL) distribution within the porous media using a nuclear magnetic resonance (NMR) method, and 4) application of a complex resistivity method to track NAPL depletion in shallow geological formation over time. A series of controlled experiments were conducted to develop the C 3 tools and methods. The critical aspects of C3 are downhole circulation of liquid nitrogen via a cooling system, the strategic use of thermal insulation to focus cooling into the core, and the use of back pressure to optimize cooling. The C3 methods were applied at two contaminated sites: 1) F.E. Warren (FEW) Air Force Base near Cheyenne, WY and 2) a former refinery in the western U.S. The results indicated that the rate of core collection using the C3 methods is on the order of 30 foot/day. The C3 methods also improve core recovery and limits potential biases associated with flowing sands. HTA of frozen core was employed at the former refinery and FEW. Porosity and fluid saturations (i.e., aqueous, non-aqueous liquid, and gas) from the former refinery indicate that given in situ freezing, the results are not biased by drainage of pore fluids from the core during sample collection. At FEW, a comparison between the results of HTA of the frozen core collected in 2014 and the results of site characterization using unfrozen core, (second-generation (2G) methods) at the same locations (performed in 2010) indicate consistently higher contaminant concentrations using C 3. Many factors contribute to the higher quantification of contaminant concentrations using C3. The most significant factor is the preservation of the sediment attributes, in particular, pore fluids and volatile organic compounds (VOCs) in comparison to the unfrozen conventional sediment core. The NMR study was performed on laboratory-fabricated sediment core to resolve NAPL distribution within the porous media qualitatively and quantitatively. The fabricated core consisted of Colorado silica sand saturated with deionized water and trichloroethylene (TCE). The cores were scanned with a BRUKER small-animal scanner (2.3 Tesla, 100 MHz) at 20 °C and while the core was frozen at -25 °C. The acquired images indicated that freezing the water within the core suppressed the NMR signals of water-bound hydrogen. The hydrogen associated with TCE was still detectable since the TCE was in its liquid state (melting point of TCE is -73 °C). Therefore, qualitative detection of TCE within the sediment core was performed via the NMR scanning by freezing the water. A one-dimensional NMR scanning method was used for quantification of TCE mass distribution within the frozen core. However, the results indicated inconsistency in estimating the total TCE mass within the porous media. Downhole NMR logging was performed at the former refinery in the western U.S. to detect NAPL and to discriminate NAPL from water in the formation. The results indicated that detection of NMR signals to discriminate NAPL from water is compromised by the noise stemming from the active facilities and/or power lines passing over the site. A laboratory experiment was performed to evaluate the electrical response of unconsolidated porous media through time (30 days) while NAPL was being depleted. Sand columns (Colorado silica sand) contaminated with methyl tert-butyl ether (MTBE, a light non-aqueous phase liquid (LNAPL)) were studied. A multilevel electrode system was used to measure electrical resistivity of impacted sand by imposing alternative current. The trend of reduction in resistivity through the depth of columns over time followed depletion of LNAPL by volatilization. Finally, a field experiment was performed at the former refinery in the western U.S. to track natural losses of LNAPL over time. Multilevel systems consisting of water samplers, thermocouples, and electrodes were installed at a clean zone (background zone) and an LNAPL-impacted zone. In situ measurements of complex resistivity and temperature were taken and water sampling was performed for each depth (from 3 to 14 feet below the ground surface at one-foot spacing) within almost a year. At both locations, the results indicated decreases in apparent resistivity below the water table over time. This trend was supported by the geochemistry of the pore fluids. Overall, results indicate that application of the electrical resistivity method to track LNAPL depletion at field sites is difficult due to multiple conflicting factors affecting the geoelectrical response of LNAPL-impacted zones over time.

The history of hexachlorobenzene accumulation in Svalbard fjords.

PubMed

Pouch, A; Zaborska, A; Pazdro, K

2018-05-24

In the present study, we investigated the spatial and historical trends of hexachlorobenzene (HCB) contamination in dated sediments of three Svalbard fjords (Kongsfjorden, Hornsund, Adventfjorden) differing in environmental conditions and human impact. HCB concentrations ranging from below limit of quantification (6.86 pg/g d.w.) to 143.99 pg/g d.w. were measured. The highest concentrations were measured in two surface sediment layers of the core collected in Hornsund near the melting glacier. The lowest concentrations of HCB were measured in Adventfjorden, suggesting that local source of HCB is not significant and global transport processes are the major transport pathways. The history of HCB deposition did not fully reflect the history of HCB emission (largest in 1950s and 1960s). In case of several sediment cores, the HCB enrichment in surface (recent) sediments was noticed. This can indicate importance of secondary sources of HCB, e.g., the influx of HCB accumulated over decades on the surface of glaciers. Detected levels of HCB were generally low and did not exceed background concentration levels; thus, a negative effect on benthic organisms is not expected.

Apportionment of polycyclic aromatic hydrocarbon sources in lower Fox River, USA, sediments by a chemical mass balance model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Su, M.C.; Christensen, E.R.; Karls, J.F.

Four sediment cores were collected from the lower Fox River, Wisconsin, USA, to identify possible sources of polycyclic aromatic hydrocarbons (PAHs) using a chemical mass balance model. The cores, which were obtained in 1995 from areas close to Green Bay, Wisconsin, USA, had total PAH concentrations between 19.3 and 0.34 ppm. To determine historical trends of PAH inputs, {sup 210}Pb and {sup 137}Cs dating was used, and elemental carbon particle analysis was done to characterize particles from the combustion of coal, wood, and petroleum. Source fingerprints were taken from the literature. Their results indicate that coke oven emissions, highway dust,more » coal gasification, and wood burning are likely sources of PAHs in the lower Fox River. Coke oven emissions are in the range of 40 to 90% of total PAHs, and this fraction decreases from 1930 to 1990, except in core Fox River-A (FR-A). The overall highway dust (HWY) contribution is between 10 and 75%, and this fraction increases from 1930 to present, except in core FR-A. The wood burning (WB) contribution is less than 7% in cores FR-B, FR-C, and FR-D. In core FR-A, a maximum ({approximately}23%) is found around 1960. The contribution of wood burning has changed from less than 6% in 1950 to between 3 and 10% in 1995. Evidence of aerobic biodegradation or photolysis in the sediment of phenanthrene, with a half-life of approximately 0.5 years has been found at the site of core FR-D, which is the shallowest (1.1 m) of the four core sites.« less

Recent advances in the use of estuarine meiobenthos to assess contaminated sediment effects in multi-species whole sediment microcosms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chandler, G.T.; Coull, B.C.; Schizas, N.V.

1995-12-31

Many marine meiobenthic taxa (i.e. invertebrates passing a 1-mm sieve but retaining on a 0.063 mm sieve) are ideal for ``whole-sediment`` and porewater bioassay of sedimented pollutants. Annual production of meiobenthos is 5--10 times that of the more commonly studied macrobenthos, and > 95% of all meiobenthos live in the oxic zone of muddy sediments at densities of 4--12 million per M{sup 2}. Most spend their entire lifecycles, burrowing freely and feeding on/within the sediment:porewater matrix, many taxa undergo 10--14 generations per year, most larval/juvenile stages are benthic, and many have easily quantifiable reproductive output. Furthermore, many meiobenthic taxa canmore » be cultured indefinitely over multiple life-cycles within simple sediment microcosms consisting of sealed whole-sediment cores collected intact from intertidal mudflats. The authors describe several recent technical developments exploiting meiofaunal sediment culture for rapid contaminated sediment bioassays of toxicant effects on survival, reproduction and population growth of meiobenthic taxa in whole-sediment microcosms. Currently meiobenthic copepods, nematodes, foraminifers and polychaetes are being continuously cultured to study these parameters under exposure to model sediment-associated toxicants (e.g. cadmium). Bioassays are run for 21-d under flowing seawater. With this approach, fertile benthic copepods (e.g. Amphiascus tenuiremis) can be added to core microcosms to assess survival and growth of a fixed population cohort. All other meiobenthic taxa are enumerated relative to controls and evaluated for toxicant effects on higher order community-level endpoints. This approach exploits meiobenthos` high abundance and rapid reproductive rates to yield on a micro scale better endpoints than much larger sediment mesocosms targeted at macrofaunal endpoints.« less

Contamination Control of Freeze Shoe Coring System for Collection of Aquifer Sands

NASA Astrophysics Data System (ADS)

Homola, K.; van Geen, A.; Spivack, A. J.; Grzybowski, B.; Schlottenmier, D.

2017-12-01

We have developed and tested an original device, the freeze-shoe coring system, designed to recover undisturbed samples of water contained in sand-dominated aquifers. Aquifer sands are notoriously difficult to collect together with porewater from coincident depths, as high hydraulic permeability leads to water drainage and mixing during retrieval. Two existing corer designs were reconfigured to incorporate the freeze-shoe system; a Hydraulic Piston (HPC) and a Rotary (RC) Corer. Once deployed, liquid CO­2 contained in an interior tank is channeled to coils at the core head where it changes phase, rapidly cooling the deepest portion of the core. The resulting frozen core material impedes water loss during recovery. We conducted contamination tests to examine the integrity of cores retrieved during a March 2017 yard test deployment. Perfluorocarbon tracer (PFC) was added to the drill fluid and recovered cores were subsampled to capture the distribution of PFC throughout the core length and interior. Samples were collected from two HPC and one RC core and analyzed for PFC concentrations. The lowest porewater contamination, around 0.01% invasive fluid, occurs in the center of both HPC cores. The greatest contamination (up to 10%) occurs at the disturbed edges where core material contacts drill fluid. There was lower contamination in the core interior than top, bottom, and edges, as well as significantly lower contamination in HPC cores that those recovered with the RC. These results confirm that the freeze-shoe system, proposed for field test deployments in West Bengal, India, can successfully collect intact porewater and sediment material with minimal if any contamination from drill fluid.

Using ground-penetrating radar and sidescan sonar to compare lake bottom geology in New England

NASA Astrophysics Data System (ADS)

Nesbitt, I. M.; Campbell, S. W.; Arcone, S. A.; Smith, S. M.

2017-12-01

Post-Laurentide Ice Sheet erosion and re-deposition has had a significant influence on the geomorphology of New England. Anthropogenic activities such as forestry, farming, and construction of infrastructure such as dams and associated lake reservoirs, has further contributed to near surface changes. Unfortunately, these surface dynamics are difficult to constrain, both in space and time. One analog that can be used to estimate erosion and deposition, lake basin sedimentation, is typically derived from lake bottom sediment core samples. Reliance on core records assumes that derived sedimentation rates are representative of the broader watershed, despite being only a single point measurement. Geophysical surveys suggest that this assumption can be highly erroneous and unrepresentative of an entire lake basin. Herein, we conducted ground-penetrating radar (GPR) and side-scan sonar (SSS) surveys of multiple lakes in Maine, New Hampshire, and Vermont which are representative of different basin types to estimate sedimentation rates since Laurentide retreat. Subsequent age constraints from cores on multiple GPR-imaged horizons could be used to refine estimates of sedimentation rate change caused by evolving physical, biological, and chemical processes that control erosion, transport, and re-deposition. This presentation will provide a summary of GPR and SSS data collection methods, assumptions and limitations, structural and surficial interpretations, and key findings from multiple lake basins in New England. Results show that GPR and SSS are efficient, cost effective, and relatively accurate tools for helping to constrain lake erosion and deposition processes.

Heavy metal distribution in sediment profiles of Tuul River, Mongolia

NASA Astrophysics Data System (ADS)

Soyol-Erdene, T. O.; Lin, S.; Tuuguu, E.; Daichaa, D.; Ulziibat, B.; Enkh-Amgalan, T.; Hsieh, I. C.

2016-12-01

The distribution, enrichment, and accumulation of heavy metals in the sediments of Tuul River, Mongolia were investigated. Sediment core samples with depths of 4.0-49 cm from thirteen locations along the Tuul River were collected in the period from Sept. 2013 to Aug. 2014 and characterized for metal contents (e.g., Al, Fe, Cu, Zn, Pb, Ni, Cd, Hg and Cr), water content, and grain size. Results showed that metal average concentrations in the sample cores varied from 0.02 mg kg-1 for Hg (0.01 - 0.03 mg kg-1) to 481 mg kg-1 for Mn (277 - 623 mg kg-1). Metal concentrations at the downstream of the capital city were higher than those at other locations. All heavy metals studied, had average enrichment factors less than 3.0, but some sites had relatively higher values of enrichment factors up to 18 for Cu, 4.1 for Hg, 5.9 for Zn, and 25 for Cr, especially at middle depth ( 8-12 cm) of the cores. Importantly, severe pollution of mercury (Hg) was found at the downstream of the capital city which requires immediate remediation before this metal propagates into the food chain. Metal concentrations correlated to the physical-chemical properties of the sediments, which suggested the influence of industrial and municipal wastewaters discharged from the nearby cities. Results of this work would help to develop strategy to remediate of Tuul river sediment and to reduce the exposure of inhabitants to toxic substances.

The dark side of the hyporheic zone: Depth profiles of nitrogen and its processing in stream sediments

USGS Publications Warehouse

Stelzer, R.S.; Bartsch, L.A.; Richardson, W.B.; Strauss, E.A.

2011-01-01

1.Although it is well known that sediments can be hot spots for nitrogen transformation in streams, many previous studies have confined measurements of denitrification and nitrate retention to shallow sediments (<5cm deep). We determined the extent of nitrate processing in deeper sediments of a sand plains stream (Emmons Creek) by measuring denitrification in core sections to a depth of 25cm and by assessing vertical nitrate profiles, with peepers and piezometers, to a depth of 70cm. 2.Denitrification rates of sediment slurries based on acetylene block were higher in shallower core sections. However, core sections deeper than 5cm accounted for 68% of the mean depth-integrated denitrification rate. 3.Vertical hydraulic gradient and vertical profiles of pore water chloride concentration suggested that deep ground water upwelled through shallow sediments before discharging to the stream channel. The results of a two-source mixing model based on chloride concentrations suggested that the hyporheic zone was very shallow (<5cm) in Emmons Creek. 4.Vertical profiles showed that nitrate concentration in shallow ground water was about 10-60% of the nitrate concentration of deep ground water. The mean nitrate concentrations of deep and shallow ground water were 2.17 and 0.73mgNO3-NL-1, respectively. 5.Deep ground water tended to be oxic (6.9mgO2L-1) but approached anoxia (0.8mgO2L-1) after passing through shallow, organic carbon-rich sediments, which suggests that the decline in the nitrate concentrations of upwelling ground water was because of denitrification. 6.Collectively, our results suggest that there is substantial nitrate removal occurring in deep sediments, below the hyporheic zone, in Emmons Creek. Our findings suggest that not accounting for nitrate removal in deep sediments could lead to underestimates of nitrogen processing in streams and catchments. ?? 2011 Blackwell Publishing Ltd.

Response of Benthic Foraminiferal Size to Oxygen Concentration in Antarctic Sediment Cores

NASA Astrophysics Data System (ADS)

Guo, D.; Keating-Bitonti, C.; Payne, J.

2014-12-01

Oxygen availability is important for biological reactions and the demand of oxygen is determined by the size of the organism. Few marine organisms can tolerate low oxygen conditions, but benthic foraminifera, a group of amoeboid protists that are highly sensitive to environmental factors, are known to live in these conditions. Benthic foraminifera may be able to live in oxygen stressed environments by changing the size and shape of their test. Low oxygen concentrations should favor smaller, thinner-shelled, flattened test morphologies. We hypothesize that the volume-to-surface area ratio of benthic foraminifera will decrease with decreasing dissolved oxygen concentrations. To test this hypothesis, we picked two calcareous species (Epistominella exigua and Cassulinoides porrectus) and one agglutinated species (Portatrochammina antarctica) from three sediment cores collected from Explorer's Cove, Antarctica. Starting at the sediment-water interface, each core spans approximately 5-8 cm of depth. Profiles of dissolved oxygen concentrations were measured at the time of collection. At specific depths within the cores, we measured the three dimensions of picked foraminiferal tests using NIS-Elements. We calculated the volume and surface area of the tests assuming the shape of the foraminifers was an ellipsoid. The size trends of E. exigua confirm our hypothesis that the test volume-to-surface area ratios correlate positively with dissolved oxygen concentrations (p-value < 0.001). However, the size trends of the other species refute our hypothesis: P. antarctica shows no correlation and C. porrectus shows a negative correlation (p-value < 0.001) to dissolved oxygen concentrations. Thus, our results show that the change in size in response to variations in dissolved oxygen concentrations is species dependent. Moreover, we find that calcareous species are more sensitive to oxygen fluctuations than agglutinated species.

An 800-year record of terrestrial organic matter from the East China Sea shelf break: Links to climate change and human activity in the Changjiang Basin

NASA Astrophysics Data System (ADS)

Li, Zhong Qiao; Wu, Ying; Liu, Su Mei; Du, Jin Zhou; Zhang, Jing

2016-02-01

The East China Sea (ECS) is a large river dominated marginal sea and receives massive volumes of terrestrial material from the Changjiang (Yangtze River). As the ECS preserves a record of terrestrial material derived from the Changjiang Basin, cores collected from this region can be used to reconstruct paleoclimate change and human disturbance in the watershed. A core (P4) was collected from the ECS shelf break and analyzed for bulk parameters (organic carbon (OC), total nitrogen (TN), and stable carbon isotopes (δ13C)), lignin phenols, and 3,5-dihydroxy benzoic acid (DHBA). The depth profiles of these parameters indicate stable and consistent marine production. The lignin source indices, cinnamyl phenols vs. vanillyl phenols (C/V) and syringyl phenols vs. vanillyl phenols (S/V), were in agreement with previously reported results from ECS surface sediments, but differed markedly from Bohai Sea surface sediments. The ratio of acid to aldehyde in vanillyl phenols ((Ad/Al)v) indicated the terrestrial OC in this core was refractory. At the same time, the variation in lignin phenols is positively correlated with the strength of the Indian Summer Monsoon (ISM) over the last 800 years (p<0.001). This is because most sediment is delivered from the upper reaches of the Changjiang Basin, where the ISM is the key control on precipitation. Two extreme drought events, around 1580 A.D. and 1770 A.D. were also identified in the core based on the extremely low C/V, S/V, lignin phenol vegetation index (LPVI), and DHBA values. Furthermore, the significant shift in C/V and S/V since 1880 A.D. is probably a reflection of increased human activity in the upper Changjiang Basin over this period.

Rescuing Paleomagnetic Data from Deep-Sea Cores Through the IEDA-CCNY Data Internship Program

NASA Astrophysics Data System (ADS)

Ismail, A.; Randel, C.; Palumbo, R. V.; Carter, M.; Cai, Y.; Kent, D. V.; Lehnert, K.; Block, K. A.

2016-12-01

Paleomagnetic data provides essential information for evaluating the chronostratigraphy of sedimentary cores. Lamont research vessels Vema and Robert Conrad collected over 10,000 deep-sea sediment cores around the world from 1953 to 1989. 10% of these cores have been sampled for paleomagnetic analyses at Lamont. Over the years, only 10% of these paleomagnetic records have been published. Moreover, data listings were only rarely made available in older publications because electronic appendices were not available and cyberinfrastructure was not in place for publishing and preserving these data. As a result, the majority of these datasets exist only as fading computer printouts in binders on the investigator's bookshelf. This summer, undergraduate students from the NSF-funded IEDA-CCNY Data Internship Program started digitizing this enormous dataset under the supervision of Dennis Kent, the current custodian of the data and one of the investigators who oversaw some of the data collection process, and an active leader in the field. Undergraduate students worked on digitizing paper records, proof-reading and organizing the data sheets for future integration into an appropriate repository. Through observing and plotting the data, the students learned about how sediment cores and paleomagnetic data are collected and used in research, and the best practices in data publishing and preservation from IEDA (Interdisciplinary Earth Data Alliance) team members. The students also compared different optical character recognition (OCR) softwares and established an efficient workflow to digitize these datasets. These datasets will eventually be incorporated in the Magnetics Information Consortium (MagIC), so that they can be easily compared with similar datasets and have the potential to generate new findings. Through this data rescue project, the students had the opportunity to learn about an important field of scientific research and interact with world-class scientists.

Sources and deposition of polycyclic aromatic hydrocarbons to western US national parks

EPA Science Inventory

Seasonal snowpack, lichens, and lake sediment cores were collected from fourteen lake catchments in eight western U.S. National Parks and analyzed for sixteen polycyclic aromatic hydrocarbons (PAHs) to determine their current and historical deposition, as well as to identify thei...

Manoomin: place-based research with Native American students on wild rice lakes on the Fond du Lac Band of Lake Superior Chippewa Reservation, northern Minnesota

NASA Astrophysics Data System (ADS)

Ito, E.; Myrbo, A.; Dalbotten, D. M.; Pellerin, H.; Greensky, L.; Howes, T.; Wold, A.; McEathron, M. A.; Shanker, V.

2010-12-01

The manoomin project is a collaboration between Fond du Lac Tribal and Community College (Cloquet, MN), the Reservation’s Resource Management Division, and the University of Minnesota funded by the NSF GEO-OEDG Program. It builds on a successful seven-year history of collaboration between these parties, including regular science camps (gidaakiimanaanimigawig, Our Earth Lodge) for students of a wide range of ages. We are working as a team with Native students to study the history of wild rice (manoomin; Zizania palustris), a culturally important resource, growing on Reservation lakes. The joint project takes two main approaches: study of sediment core samples collected from Reservation lakes; and the collection of traditional knowledge about wild rice from the Elders. Science campers collect lake cores during winter with the assistance of the U of MN’s LacCore (National Lacustrine Core Facility) and Resource Management and visit LacCore to log, split and describe cores soon thereafter. Academic mentors with a range of specialties (phytoliths, pollen, plant macrofossils, sedimentology, geochemistry, magnetics) spend 1-2 weeks during the summer with small groups of college-age (>18, many nontraditional) student interns working on a particular paleoenvironmental proxy from the sediment cores. Younger students (middle and high school) also work in small teams in half day units with the same mentors. All campers become comfortable in an academic setting, gain experience working in research labs learning and practicing techniques, and jointly interpret collective results. The continuation of the project over five years (2009-2014) will allow these students to develop relationships with scientists and to receive mentoring beyond the laboratory as they make transitions into 2- and 4-year colleges and into graduate school. Their research provides historical and environmental information that is relevant to their own land that will be used by Resource Management which is charged to protect the wild rice and to improve its growth to better understand these ecosystems in the context of current global and local change. A substantial evaluation component charts progress and provides feedback to project participants and the larger community.

Marine sedimentary coring and high-quality, multi-proxy records in the high-latitude North Pacific: a synthesis of paleoceanographic cruise and research effort

NASA Astrophysics Data System (ADS)

Borreggine, M. J.; Myhre, S. E.; Smith-Mislan, A.; Davis, C. V.; Deutsch, C.

2016-12-01

We assessed sedimentary coring efforts, data acquisition and publications from the subpolar North Pacific and marginal seas from 1951-2015. We found a total of 1,249 sediment cores collected by American, French, Japanese and Russian research vessels across the Subarctic Pacific (639 cores), Alaskan Gyre (8 cores), Sea of Okhotsk (270 cores), Bering Sea (120 cores), and the Sea of Japan (212 cores). Of these, 27% are investigated in peer-reviewed publications; this fraction varies from the Subarctic Pacific (18%), Alaskan Gyre (100%), Sea of Okhotsk (33%), Bering Sea (57%), and the Sea of Japan (25%). We assess the biological, geochemical, isotopic, and stratigraphic lines of evidence available for these cores, alongside coring technology, location, depth, cruise and vessel metadata. Coring effort peaked in 1996, 2009, and 2010 where 86, 90, and 67 cores, respectively, were recovered in the five regions collectively. Piston cores are the most common (347 cores) of the 24 different coring technologies used in the last 64 years. Published sedimentation rates range across the Subarctic Pacific (0.132-208 cm/ka), Alaskan Gyre (9-10,000 cm/ka), Sea of Okhotsk (0.7-115.5 cm/ka), Bering Sea (3-250 cm/ka), and the Sea of Japan (0.5-25 cm/ka), with the highest rates in the Alaskan Gyre. Age model development has transitioned from singular techniques to multiproxy approaches. Recent chronologies are built using a mix of isotope stratigraphy, radiocarbon dating, magnetostratigraphy, biostratigraphy, tephrochronology, % opal, color, and lithophysical proxies. Out of 275 published chronologies for the North Pacific, 132 (48%) are built with radiocarbon dating. Sedimentary data in the North Pacific includes biological, geochemical, isotopic, and stratigraphic analyses, and we document all proxy evidence to-date across all cores assessed. This database of coring and publication provides a unique resource and comprehensive assessment to the paleoceanographic community, can be used to identify strengths and weaknesses in North Pacific paleoceanography, and will be made publicly available. Additionally, the database is used to recreate past sea ice, temperature, and oxygen conditions in two additional submissions at the 2016 AGU Fall Meeting.

Multivariate analysis and geochemical approach for assessment of metal pollution state in sediment cores.

PubMed

Jamshidi-Zanjani, Ahmad; Saeedi, Mohsen

2017-07-01

Vertical distribution of metals (Cu, Zn, Cr, Fe, Mn, Pb, Ni, Cd, and Li) in four sediment core samples (C 1 , C 2 , C 3 , and C 4 ) from Anzali international wetland located southwest of the Caspian Sea was examined. Background concentration of each metal was calculated according to different statistical approaches. The results of multivariate statistical analysis showed that Fe and Mn might have significant role in the fate of Ni and Zn in sediment core samples. Different sediment quality indexes were utilized to assess metal pollution in sediment cores. Moreover, a new sediment quality index named aggregative toxicity index (ATI) based on sediment quality guidelines (SQGs) was developed to assess the degree of metal toxicity in an aggregative manner. The increasing pattern of metal pollution and their toxicity degree in upper layers of core samples indicated increasing effects of anthropogenic sources in the study area.

Distinct Bacterial Communities in Surficial Seafloor Sediments Following the 2010 Deepwater Horizon Blowout.

PubMed

Yang, Tingting; Speare, Kelly; McKay, Luke; MacGregor, Barbara J; Joye, Samantha B; Teske, Andreas

2016-01-01

A major fraction of the petroleum hydrocarbons discharged during the 2010 Macondo oil spill became associated with and sank to the seafloor as marine snow flocs. This sedimentation pulse induced the development of distinct bacterial communities. Between May 2010 and July 2011, full-length 16S rRNA gene clone libraries demonstrated bacterial community succession in oil-polluted sediment samples near the wellhead area. Libraries from early May 2010, before the sedimentation event, served as the baseline control. Freshly deposited oil-derived marine snow was collected on the surface of sediment cores in September 2010, and was characterized by abundantly detected members of the marine Roseobacter cluster within the Alphaproteobacteria. Samples collected in mid-October 2010 closest to the wellhead contained members of the sulfate-reducing, anaerobic bacterial families Desulfobacteraceae and Desulfobulbaceae within the Deltaproteobacteria, suggesting that the oil-derived sedimentation pulse triggered bacterial oxygen consumption and created patchy anaerobic microniches that favored sulfate-reducing bacteria. Phylotypes of the polycyclic aromatic hydrocarbon-degrading genus Cycloclasticus, previously found both in surface oil slicks and the deep hydrocarbon plume, were also found in oil-derived marine snow flocs sedimenting on the seafloor in September 2010, and in surficial sediments collected in October and November 2010, but not in any of the control samples. Due to the relative recalcitrance and stability of polycyclic aromatic compounds, Cycloclasticus represents the most persistent microbial marker of seafloor hydrocarbon deposition that we could identify in this dataset. The bacterial imprint of the DWH oil spill had diminished in late November 2010, when the bacterial communities in oil-impacted sediment samples collected near the Macondo wellhead began to resemble their pre-spill counterparts and spatial controls. Samples collected in summer of 2011 did not show a consistent bacterial community signature, suggesting that the bacterial community was no longer shaped by the DWH fallout of oil-derived marine snow, but instead by location-specific and seasonal factors.

Distinct Bacterial Communities in Surficial Seafloor Sediments Following the 2010 Deepwater Horizon Blowout

PubMed Central

Yang, Tingting; Speare, Kelly; McKay, Luke; MacGregor, Barbara J.; Joye, Samantha B.; Teske, Andreas

2016-01-01

A major fraction of the petroleum hydrocarbons discharged during the 2010 Macondo oil spill became associated with and sank to the seafloor as marine snow flocs. This sedimentation pulse induced the development of distinct bacterial communities. Between May 2010 and July 2011, full-length 16S rRNA gene clone libraries demonstrated bacterial community succession in oil-polluted sediment samples near the wellhead area. Libraries from early May 2010, before the sedimentation event, served as the baseline control. Freshly deposited oil-derived marine snow was collected on the surface of sediment cores in September 2010, and was characterized by abundantly detected members of the marine Roseobacter cluster within the Alphaproteobacteria. Samples collected in mid-October 2010 closest to the wellhead contained members of the sulfate-reducing, anaerobic bacterial families Desulfobacteraceae and Desulfobulbaceae within the Deltaproteobacteria, suggesting that the oil-derived sedimentation pulse triggered bacterial oxygen consumption and created patchy anaerobic microniches that favored sulfate-reducing bacteria. Phylotypes of the polycyclic aromatic hydrocarbon-degrading genus Cycloclasticus, previously found both in surface oil slicks and the deep hydrocarbon plume, were also found in oil-derived marine snow flocs sedimenting on the seafloor in September 2010, and in surficial sediments collected in October and November 2010, but not in any of the control samples. Due to the relative recalcitrance and stability of polycyclic aromatic compounds, Cycloclasticus represents the most persistent microbial marker of seafloor hydrocarbon deposition that we could identify in this dataset. The bacterial imprint of the DWH oil spill had diminished in late November 2010, when the bacterial communities in oil-impacted sediment samples collected near the Macondo wellhead began to resemble their pre-spill counterparts and spatial controls. Samples collected in summer of 2011 did not show a consistent bacterial community signature, suggesting that the bacterial community was no longer shaped by the DWH fallout of oil-derived marine snow, but instead by location-specific and seasonal factors. PMID:27679609

PAH concentrations in lake sediment decline following ban on coal-tar-based pavement sealants in Austin, Texas

USGS Publications Warehouse

Van Metre, Peter C.; Mahler, Barbara J.

2013-01-01

Recent studies have concluded that coal-tar-based pavement sealants are a major source of polycyclic aromatic hydrocarbons (PAHs) in urban settings in large parts of the United States. In 2006, Austin, TX, became the first jurisdiction in the U.S. to ban the use of coal-tar sealants. We evaluated the effect of Austin’s ban by analyzing PAHs in sediment cores and bottom-sediment samples collected in 1998, 2000, 2001, 2012, and 2014 from Lady Bird Lake, the principal receiving water body for Austin urban runoff. The sum concentration of the 16 EPA Priority Pollutant PAHs (∑PAH16) in dated core intervals and surficial bottom-sediment samples collected from sites in the lower lake declined about 44% from 1998–2005 to 2006–2014 (means of 7980 and 4500 μg kg–1, respectively), and by 2012–2014, the decline was about 58% (mean of 3320 μg kg–1). Concentrations of ∑PAH16 in bottom sediment from two of three mid-lake sites decreased by about 71 and 35% from 2001 to 2014. Concentrations at a third site increased by about 14% from 2001 to 2014. The decreases since 2006 reverse a 40-year (1959–1998) upward trend. Despite declines in PAH concentrations, PAH profiles and source-receptor modeling results indicate that coal-tar sealants remain the largest PAH source to the lake, implying that PAH concentrations likely will continue to decline as stocks of previously applied sealant gradually become depleted.

Site 765: Sediment Lithostratigraphy

USGS Publications Warehouse

,

1990-01-01

A 935-m-thick succession of Quaternary through Lower Cretaceous sediments was recovered at Site 765 (Fig. 10). A single core of Quaternary sediment was obtained from Hole 765A; drilling terminated and a new hole was drilled in an attempt to establish the mud line. Quaternary through middle Miocene sediments were cored in Hole 765B down to a depth of 395.6 mbsf. Middle Miocene through Lower Cretaceous sediments were cored in Hole 765C, after washing the interval between 0 and 350.2 mbsf. Exact lithologic correlation of the basal cores from Hole 765B with the upper cores from Hole 765C is not possible because of poor recovery; hence, correlation is based solely on matching sub-bottom depths.

Organic geochemistry of sediments from the continental margin off southern New England, U.S.A.--Part II. Lipids

NASA Technical Reports Server (NTRS)

Venkatesan, M. I.; Ruth, E.; Steinberg, S.; Kaplan, I. R.

1987-01-01

Organic geochemical measurements of the lipid fraction, comparing saturated and aromatic hydrocarbons, fatty acids, alcohols and sterols, have been carried out on six sediments cores collected from the Atlantic shelf, slope and the rise areas to evaluate the cross-shelf transport of the organic carbon. The concentration of most of the organic compound classes studied is correlated with the total organic carbon, which decreases from the shelf through slope to the rise. Terrigenous carbon is recognizable even in the slope and rise sediments, but terrestrial influx decreases relative to marine generated lipids in the slope and rise organic matter. We estimate that approximately 50% of the shelf organic matter is exported to the slope. Data of sediment trap material collected at 1200 m from 1250 m water depth are discussed and compared with that of surface sediment from 1280 m water depth (slope). Fluxes for specific organic compound classes have been computed. The fluxes are of the same magnitude as for equatorial North Atlantic trap particulates at comparable water depth, studied by other investigations.

Spatial and temporal trends in PCBs in sediment along the lower Rhone River, France

USGS Publications Warehouse

Desmet, Marc; Mourier, Brice; Mahler, Barbara J.; Van Metre, Peter C.; Roux, Gwenaelle; Persat, Henri; Lefevre, Irene; Peretti, Annie; Chapron, Emmanuel; Anaelle, Simonneau; Miege, Cecile; Babut, Marc

2012-01-01

Despite increasingly strict control of polychlorinated biphenyl (PCB) releases in France since the mid-1970s, PCB contamination of fish recently has emerged as a major concern in the lower Rhone River basin. We measured PCB concentrations in Rhone sediment to evaluate the effects of PCB releases from major urban and industrial areas, sediment redistribution by large floods, and regulatory controls on PCB trends from 1970 to present. Profiles of PCBs (the sum of seven indicator PCB congeners) were reconstructed from sediment cores collected from an off-river rural reference site and from three depositional areas along the Rhone upstream and downstream from the city of Lyon, France. Core chronology was determined from radionuclide profiles and flood deposits. PCB concentrations increased progressively in the downstream direction, and reached a maximum concentration in 1991 of 281 μg/kg at the most downstream site. At the rural reference site and at the upstream Rhone site, PCB concentrations peaked in the 1970s (maximum concentration of 13 and 78 μg/kg, respectively) and have decreased exponentially since then. PCB concentrations in the middle and downstream cores were elevated into the early 1990s, decreased very rapidly until 2000, and since then have remained relatively stable. Congener profiles for three time windows (1965–80, 1986–93, and 2000–08) were similar in the three sediment cores from the Rhone and different from those at the rural reference site. The results indicate that permitted discharges from a hazardous-waste treatment facility upstream from Lyon might have contributed to high concentrations into the 1980-90s, but that industrial discharges from the greater Lyon area and tributaries to the Rhone near Lyon have had a greater contribution since the 1990s. There is little indication that PCB concentration in sediments downstream from Lyon will decrease over at least the short term.

Uranium and plutonium in anoxic marine sediments of the Santiago River mouth (Eastern Pacific, Mexico).

PubMed

Almazán-Torres, María Guadalupe; Ordóñez-Regil, Eduardo; Ruiz-Fernández, Ana Carolina

2016-11-01

The uranium (U) and plutonium (Pu) content with depth in a sediment core collected in the continental shelf off the mouth of the Santiago River in the Mexican Pacific was studied to evaluate the contamination effects of the effluent of the Santiago-Lerma River as it moves into the sea. The large mass of terrestrial detritus delivered by the river influences the physicochemical and geochemical processes in the seafloor. Abnormal concentrations of U and Pu in sediments were examined as indicative of the effects of anoxic conditions. One of the indicators of pollution of seawater is the bacterial activity of the shallow seabed layer; and among the prevailing bacteria, the magnetotactic ones induce the formation of euhedral and framboidal shapes (pyrite). These pyrite entities are by-products of anoxic environments loaded with decomposing detrital material and are very abundant in the surface layers of the sediment core analyzed. The pyrite formation is the result of a biochemical reaction between iron and organic sulphur reduced by bacteria, and the pyrite entities precipitate to the seafloor. In the same upper zone of the profile, 238 U is readily immobilized, while 234 U is oxidized and dissolved in seawater by the effect of hot atom chemistry. This may cause the activity ratio (AR) 234 U/ 238 U disequilibrium (near 0.41). Furthermore, in the shallow layer of the sediment core, an abnormally high concentration of 239+240 Pu was detected. In this upper layer, the activity concentrations found were 3.19 Bq kg -1 for 238 U, 1.32 kg -1 for 234 U and 2.78 Bq kg -1 for 239+240 Pu. In the lower fractions of the sediment core, normal values of AR 234 U/ 238 U (≈1) were found, with traces of 239+240 Pu. Copyright © 2016 Elsevier Ltd. All rights reserved.

Influence of Diagenesis on Bioavailable Phosphorus in Lake Mendota, USA

NASA Astrophysics Data System (ADS)

Hoffman, A.; Armstrong, D.; Lathrop, R.; Penn, M.

2013-12-01

Phosphorus (P) is a major driver of productivity in many freshwater systems and in excess P can cause a variety of deleterious effects. Lake Mendota, located in Madison, Wisconsin (USA), is a eutrophic calcareous lake that is influenced by both urban and agricultural sources. As measures have been implemented to control point and non-point source pollution, internal sources, including release by sediments, has become more important. We collected multiple sediment cores from seven depositional basins to determine how diagenesis is influencing the bioavailability of sediment P. Cores were sliced in 1-cm intervals and analyzed for total P (TP), various P fractions, total metals, and multiple stable isotopes. While the average amount of total P that was bioavailable was 64.8%, the range noted was 39.2% to 88.6%. Spatial differences existed among the cores when comparing TP and bioavailable P among the cores. Depth profiles elucidated temporal differences as occasional increases in TP with depth were noted. These increases were found to contain a higher percent of bioavailable P. This variation was explored to determine if it resulted from differences in source material, for example inorganic P formed by diagenesis of organic P (algal derived) rather than soil P from external inputs. Saturation index modeling using MINEQL+ suggests that phosphorus concentrations in Lake Mendota pore waters are influenced by precipitation of vivianite (Fe3(PO4)2●8H2O) and certain calcium phosphates. However, hydroxyl apatite (Ca5(PO4)3(OH)), was highly supersaturated, indicating that precipitation of hydroxyl apatite is hindered and not important in controlling phosphate concentrations in these sediments. Yet even more important than precipitation reactions, adsorption/desorption characteristics of P seem to play a major role in P bioavailability. Sediment 210Pb and 137Cs activity profiles indicate differences exist among sedimentation rates for the various depositional sites in Lake Mendota. Implications for the modeling of P cycling and changes in internal loading following external P reduction in lakes will be discussed.

Characteristic sediment and water column chlorophyll-a in the sea cucumber’s Paracaudina sp. habitat on the Kenjeran Water, Surabaya

NASA Astrophysics Data System (ADS)

Widianingsih, W.; Zaenuri, M.; Anggoro, S.; Kusumaningrum, H. P.; Hartati, R.

2018-03-01

The study of characteristic sediment and water column chlorophyll-a has an important role in the sea cucumber habitat. Sediment chlorophyll-a represents a productivity primer for the benthic community. This research has a purpose to investigate characteristic sediment and water column chlorophyll-a on the Kenjeran water, Surabaya. Sediment samples were collected by the ekman grab for analysis, grain size and nutrient. The sample for sediment chlorophyll-a was taken by core sampler. The water samples were taken with Nansen Bottles. According to the research result, the values of sediment chlorophyll-a at station 10, 11 and 12 were higher than the other stations. In contrast, the value of chlorophyll-a in the column water had almost the same value for each station. The sediment chlorophyll-a value on clay and silt sediment type was higher than the fine sand and coarse sediment type. The suitable habitat characteristic for Paracaudina sp. was clay and silt sediment with sediment chlorophyll concentration ranging from 347.82 mg·m-2 to 1135.52 mg·m-2.

The Contribution of Opal-Associated Phosphorus to Bioavailable Phosphorus in Surface and Core Sediments in the East China Sea

NASA Astrophysics Data System (ADS)

Li, Huanxin; He, Huijun; Yang, Shifeng; Liu, Yanli; Che, Hong; Li, Mujian; Zhang, Jing

2018-06-01

To improve the burial flux calculations of bioavailable phosphorus (P) and study opal-associated P (Opal-P) in the East China Sea (ECS), surface and core sediments were collected in the Changjiang Estuary (CE) and the south of the Cheju Island. In this study, sedimentary P was operationally divided into seven different forms using modified sedimentary extraction (SEDEX) technique: LSor-P (exchangeable or loosely sorbed P), Fe-P (easily reducible or reactive ferric Fe-bound P), CFA-P (authigenic carbonate fluorapatite and biogenic apatite and CaCO3-bound P), Detr-P (detrital apatite), Org-P (organic P), Opal-P and Ref-P (refractory P). The data revealed that the concentrations of the seven different P forms rank as Detr-P > CFA-P > Org-P > Ref-P > Opal-P > Fe-P > LSor-P in surface sediments and CFA-P > Detr-P > Org-P > Ref-P > Fe-P > Opal-P > LSor-P in core sediments. The distributions of the total phosphorus (TP), TIP, CFA-P, Detr-P are similar and decrease from the CE to the south of the Cheju Island. Meanwhile, Org-P and Opal-P exhibit different distribution trends; this may be affected by the grain size and TOM. The concentrations of potentially bioavailable P are 9.6-13.0 μmol g-1 and 10.0-13.6 μmol g-1, representing 61%-70% and 41%-64% of the TP in surface and core sediments, respectively. The concentrations of Opal-P are 0.6-2.3 μmol g-1 and 0.6-1.4 μmol g-1 in surface and core sediments, accounting for 5.3%-19.8% and 4.2%-10.6% of bioavailable P, respectively. The total burial fluxes of Opal-P and bioavailable P are 1.4×109 mol yr-1 and 1.1×1010 mol yr-1 in the ECS, respectively. Opal-P represents about 12.7% of potentially bioavailable P, which should be recognized when studying P cycling in marine ecosystems.

Late Holocene sea ice conditions in Herald Canyon, Chukchi Sea

NASA Astrophysics Data System (ADS)

Pearce, C.; O'Regan, M.; Rattray, J. E.; Hutchinson, D. K.; Cronin, T. M.; Gemery, L.; Barrientos, N.; Coxall, H.; Smittenberg, R.; Semiletov, I. P.; Jakobsson, M.

2017-12-01

Sea ice in the Arctic Ocean has been in steady decline in recent decades and, based on satellite data, the retreat is most pronounced in the Chukchi and Beaufort seas. Historical observations suggest that the recent changes were unprecedented during the last 150 years, but for a longer time perspective, we rely on the geological record. For this study, we analyzed sediment samples from two piston cores from Herald Canyon in the Chukchi Sea, collected during the 2014 SWERUS-C3 Arctic Ocean Expedition. The Herald Canyon is a local depression across the Chukchi Shelf, and acts as one of the main pathways for Pacific Water to the Arctic Ocean after entering through the narrow and shallow Bering Strait. The study site lies at the modern-day seasonal sea ice minimum edge, and is thus an ideal location for the reconstruction of past sea ice variability. Both sediment cores contain late Holocene deposits characterized by high sediment accumulation rates (100-300 cm/kyr). Core 2-PC1 from the shallow canyon flank (57 m water depth) is 8 meter long and extends back to 4200 cal yrs BP, while the upper 3 meters of Core 4-PC1 from the central canyon (120 mwd) cover the last 3000 years. The chronologies of the cores are based on radiocarbon dates and the 3.6 ka Aniakchak CFE II tephra, which is used as an absolute age marker to calculate the marine radiocarbon reservoir age. Analysis of biomarkers for sea ice and surface water productivity indicate stable sea ice conditions throughout the entire late Holocene, ending with an abrupt increase of phytoplankton sterols in the very top of both sediment sequences. The shift is accompanied by a sudden increase in coarse sediments (> 125 µm) and a minor change in δ13Corg. We interpret this transition in the top sediments as a community turnover in primary producers from sea ice to open water biota. Most importantly, our results indicate that the ongoing rapid ice retreat in the Chukchi Sea of recent decades was unprecedented during the last 4000 years.

The Environment Quality, Speciation and their Origins of Heavy Metals in Surficial Sediments in Central Bohai Sea, China

NASA Astrophysics Data System (ADS)

Liu, M.; Fan, D.; Han, Z.; Liao, Y.; Chen, B.; Yang, Z.

2016-02-01

The concentrations and speciations of heavy metals (Cu, Co, Ni, Zn, Pb, Cr and Cd) in surface and core sediments collected from the central Bohai Sea were analyzed by ICP-MS, to evaluate their distribution / fractionation, pollution status and sources. The results showed that Cd exhibited gradual increasing vertically, while others were stable or declined slightly in core sediments. Metals showed higher values in `central mud area of the Bohai Sea' and the coastal area of the Bohai Bay in surface sediments. Residual fractions were the dominant forms of Cu, Co, Ni, Zn and Cr in the surface sediments, while Cd and Pb had large proportions of the total concentration in the non-residual fractions. Both the contamination factors and the geo-accumulation index indicated that Cu, Co, Ni, Cr were not polluted, while Pb, Zn, Cd were in moderate contamination. The ecological risk assessment (by sepeciations) indicated that the sediments were unpolluted with respect to the heavy metals Co, Ni and Cr and unpolluted to moderately polluted with respect to Cu, Zn, Cd and Pb. Compared with sediment quality guidelines (SQGs), Cu, Zn, Cr, Pb, Cd were likely to produce occasional adverse biological effects, while Ni showed possible ecotoxicological risks. The combined levels of the metals have a 21% probability of being toxic. Elements Cr, Co and Ni were mainly natural origined and significantly affected by the composition of sediments. Cu, Zn, Pb and especially Cd may be influenced by human activities.

Isotope analyses of the lake sediments in the Plitvice Lakes, Croatia

NASA Astrophysics Data System (ADS)

Horvatinčić, Nada; Sironić, Andreja; Barešić, Jadranka; Bronić, Ines Krajcar; Nikolov, Jovana; Todorović, Nataša; Hansman, Jan; Krmar, Miodrag

2014-10-01

The analyses of radioactive isotopes 14C, 137Cs and 210Pb, and stable isotope 13C were performed in the sediment cores, top 40 cm, taken in 2011 from karst lakes Prošće and Kozjak in the Plitvice Lakes National Park, central Croatia. Frozen sediment cores were cut into 1 cm thick layers and dried. 14C activity in both carbonate and organic fractions was measured using accelerator mass spectrometry technique with graphite synthesis. 137Cs, 210Pb, 214Pb and 214Bi were measured by low level gamma spectrometry method on ORTECHPGe detector with the efficiency of 32%. Distribution of 14C activity from both lakes showed increase of the 14C activity in the top 10-12 cm in both carbonate and organic fractions as a response to thermonuclear bomb-produced 14C in the atmosphere in the sixties of the 20th century. Anthropogenically produced 137Cs was also observed in sediment profiles. Sedimentation rates for both lake sediments were estimated based on the unsupported 210Pb activity. Different 14C activity of the carbonate fraction (63-80 pMC, percent of modern carbon) and organic fraction (82-93 pMC) is the result of geochemical and biological processes of the sediment precipitation in the lake waters. This is also confirmed by the δ 13 C values of both fractions. Carbon isotope composition, a 14 C and δ 13 C, was compared with the lake sediments from the same lakes collected in 1989 and 2003.

Multiproxy records of Holocene climate and glacier variability from sediment cores in the Cordillera Vilcabamba of southern Peru

NASA Astrophysics Data System (ADS)

Schweinsberg, A. D.; Licciardi, J. M.; Rodbell, D. T.; Stansell, N.; Tapia, P. M.

2012-12-01

Sediments contained in glacier-fed lakes and bogs provide continuous high-resolution records of glacial activity, and preserve multiproxy evidence of Holocene climate change. Tropical glacier fluctuations offer critical insight on regional paleoclimatic trends and controls, however, continuous sediment records of past tropical climates are limited. Recent cosmogenic 10Be surface exposure ages of moraine sequences in the Cordillera Vilcabamba of southern Peru (13°20'S latitude) reveal a glacial culmination during the early Holocene and a less extensive glaciation coincident with the Little Ice Age of the Northern Hemisphere. Here we supplement the existing 10Be moraine chronology with the first continuous records of multiproxy climate data in this mountain range from sediment cores recovered from bogs in direct stratigraphic contact with 10Be-dated moraines. Radiocarbon-dated sedimentological changes in a 2-meter long bog core reveal that the Holocene is characterized by alternating inorganic and organic-rich laminae, suggesting high-frequency climatic variability. Carbon measurements, bulk density, and bulk sedimentation rates are used to derive a record of clastic sediment flux that serves as a proxy indicator of former glacier activity. Preliminary analyses of the bog core reveal approximately 70 diatom taxa that indicate both rheophilic and lentic environments. Initial results show a general decrease in magnetic susceptibility and clastic flux throughout the early to mid-Holocene, which suggests an interval of deglaciation. An episode of high clastic flux from 3.8 to 2.0 ka may reflect a late Holocene glacial readvance. Volcanic glass fragments and an anomalous peak in magnetic susceptibility may correspond to the historical 1600 AD eruption of Huaynaputina. Ten new bog and lake sediment cores were collected during the 2012 field expedition and analytical measurements are underway. Ongoing efforts are focused on analyzing diatom assemblage data, developing detailed records of biogenic silica, clastic sediment flux, and magnetic susceptibility, and augmenting the 10Be moraine chronology with precise limiting radiocarbon ages to provide a more comprehensive assessment of regional climate and environmental indicators. These new paleoclimatic records will fill a large geographic gap in available proxy data and contribute toward a more complete understanding of Holocene climate variability in southern Peru. In addition, the basal radiocarbon ages being developed from sediments in contact with 10Be-dated moraines will place limits on the cosmogenic 10Be production rate in the high Andes.

Inorganic nitrogen transformations in the bed of the Shingobee River, Minnesota: Integrating hydrologic and biological processes using sediment perfusion cores

USGS Publications Warehouse

Sheibley, R.W.; Duff, J.H.; Jackman, A.P.; Triska, F.J.

2003-01-01

Inorganic N transformations were examined in streambed sediments from the Shingobee River using sediment perfusion cores. The experimental design simulated groundwater-stream water mixing within sediment cores, which provided a well-defined one-dimensional representation of in situ hydrologic conditions. Two distinct hydrologic and chemical settings were preserved in the sediment cores: the lowermost sediments, perfused with groundwater, remained anaerobic during the incubations, whereas the uppermost sediments, perfused with oxic water pumped from the overlying water column, simulated stream water penetration into the bed. The maintenance of oxic and anoxic zones formed a biologically active aerobic-anaerobic interface. Ammonium (NH4+) dissolved in groundwater was transported conservatively through the lower core zone but was removed as it mixed with aerated recycle water. Concurrently, a small quantity of nitrate (NO3-) equaling ???25% of the NH4+ loss was produced in the upper sediments. The NH4+ and NO3- profiles in the uppermost sediments resulted from coupled nitrification-denitrification, because assimilation and sorption were negligible. We hypothesize that anaerobic microsites within the aerated upper sediments supported denitrification. Rates of nitrification and denitrification in the perfusion cores ranged 42-209 and 53-160 mg N m-2 day-1, respectively. The use of modified perfusion cores permitted the identification and quantification of N transformations and verified process control by surface water exchange into the shallow hyporheic zone of the Shingobee River.

Integrated monitoring approach to investigate the contamination, mobilization and risks of sediments

NASA Astrophysics Data System (ADS)

Bölscher, Jens; Schulte, Achim; Terytze, Konstantin

2017-04-01

The use of surface water bodies for manufacturing purposes has been common not only in Germany since the beginning of industrialization, and this has led to a high accumulation of different chemical contaminants in the sediments of aquatic ecosystems. In particular, water bodies with very low flow conditions like the "Rummelsburger See", an anabranch of the Spree River located in the centre of Berlin, have been highly affected. Given that, it has become necessary to obtain improved knowledge concerning the current sediment dynamics, the rate of sedimentation and the current level of contamination and toxicity compared to earlier conditions. Against this background, a survey was set up, consisting of an integrated monitoring approach that focuses on hydraulics, sediment dynamics and contamination, including boundary conditions, such as weather and motor-boat activities to find information, which would help design appropriate treatment in the future. To detect the spatial distribution of pollutants in the sediment, over 200 sediment samples were collected via drill cores at 16 locations. The upper 15 cm of each drill core was systematically divided into 5 layers (each of 3 cm) for separate examination. The investigation of sediment deposition and remobilisation rates was accomplished by installing 18 sediment traps. The presence of selected heavy metals and organic pollutants in the sediments was determined for every sampling location and layer of the drill cores, as well as for all sediment traps. Changes in boundary conditions which influence the spatial and temporal distribution of deposition and resuspension were monitored by placing devices within the water body and taking different mobile measurements (3-D flow conditions, oxygen, turbidity, chlorophyll-a, temperature). The analysis of sediment and suspended matter included the determination of the total content of inorganic (Hg, Cd, Cr, Pb, Ni, Cu, Zn) and organic compounds (polycyclic aromatic hydrocarbons (PAH), total petroleum hydrocarbons (TPH), selected nitro-compounds, selected organotin compounds and polychlorinated biphenyls (PCB, AOX and EOX) in the sediment and suspended matter. The physico-chemical conditions of the samples were examined as well. The research into soluble and mobilizable sediment-bounded pollutants is based upon a 24 hour batch test. Certain toxic effects of the sediments were determined by different ecotoxicological test methods. In addition, the thresholds of the sediment quality guidelines published by de Deckere et al. (2011) were used to assess the solid contents. Because of the high concentrations of the pollutants, the consensus 2 values are used as thresholds in this study. The results provide important details on the spatial and temporal distribution of sedimentation and contamination. All sediments of the analysed cores and traps remain highly contaminated with heavy metals and organic compounds. The results indicate the resuspension, transport and accumulation of these sediments and show at least that toxic effects for the benthic taxa are expected. This kind of approach is necessary to create a basis for a remediation programme for, and a risk assessment of, polluted water bodies.

[History of heavy metal pollution from tidal flat in Haizhou Bay].

PubMed

Zhang, Rui; Zhang, Fan; Liu, Fu-Cheng; Yin, Fu-Jun; Ding, Ying-Jun; Gao, Jin-Rong; Chen, Jing; Shao, Wei

2013-03-01

Coastal zone could be considered as an important sink of regional source to sink and preserve historical records of environmental evolution. Four sediment cores, collected from tidal flat at Haizhou Bay near Lianyungang City, were examined for concentrations of heavy metals including Cd, Cr, Cu, Mn, Pb and Zn in core sediments to investigate the historical input of trace metals. In addition, sediment rates of cores LH3 and LH4 were determined based on radionuclide 210Pb. The results showed that grain size control effect was not the main factor that influenced the distribution of heavy metals. Heavy metals concentrations in the surface sediments were higher than these regional background values. Furthermore, Al element as a proxy of grain size was selected for normalization and calculation of metal enrichment factor (EF) and anthropogenic heavy metal fluxes. The results revealed that heavy metals in tidal flats were continuously enriched in the past decades, meanwhile, tidal flats have been significantly subjected to contaminations due to anthropogenic activities. Moreover, the depth profiles of heavy metals fluxes correspond to scenario of social-economy development of Lianyungang, which is an important urban area near Haizhou Bay. From 1950s to 2005, anthropogenic fluxes of metals increased with fluctuations, whereas, since 2005 anthropogenic fluxes declined, which may be correlated to the adjustment of industrial structure as well as the strengthened environmental regulation.

Late Quaternary carbonate accumulation along eastern South Atlantic Ocean

NASA Astrophysics Data System (ADS)

Crabill, K.; Slowey, N. C.; Foreman, A. D.; Charles, C.

2016-12-01

Water masses originating from both the North Atlantic Ocean and the Southern Ocean intersect the Walvis Ridge and Namibian margin of southwest Africa. Changes in the distribution and properties of these water masses through time are reflected by variations in the nature of the sediments accumulating along this margin. A suite of piston and gravity cores that possess sediment records corresponding to the most recent glacial-interglacial cycles were collected from the water depth range of 550 to 3700 meters. Sediment dry bulk density, XRF analyses and the concentration of CaCO3 were precisely determined at regular depth intervals in these cores. Foraminiferal δ18O along with XRF Fe/Ca data provide an age-depth model for key cores. The age-depth model and dry bulk density will be used with the calcium carbonate contents to calculate the accumulation rates of CaCO3 during each MIS 1-5e. The spatial and temporal variability in both the CaCO3 content and the CaCO3 mass accumulation rates along the Namibian continental slope will be described. Based on comparisons of these two parameters, inferences will be made about how variations of CaCO3 production, dilution of by non-CaCO3 sediment components, and dissolution of CaCO3 due to changes in ocean circulation/climate have occurred during intervals of the last glacial-interglacial cycle.

Centennial record of anthropogenic impacts in Galveston Bay: Evidence from trace metals (Hg, Pb, Ni, Zn) and lignin oxidation products.

PubMed

Al Mukaimi, Mohammad E; Kaiser, Karl; Williams, Joshua R; Dellapenna, Timothy M; Louchouarn, Patrick; Santschi, Peter H

2018-06-01

During the 20th century the impacts of industrialization and urbanization in Galveston Bay resulted in significant shifts in trace metals (Hg, Pb, Ni, Zn) and vascular plant biomarkers (lignin phenols) recorded within the surface sediments and sediment cores profile. A total of 22 sediment cores were collected in Galveston Bay in order to reconstruct the historical input of Hg, Pb, Ni, Zn and terrestrial organic matter. Total Hg (T-Hg) concentration ranged between 6 and 162 ng g -1 in surface sediments, and showed decreasing concentrations southward from the Houston Ship Channel (HSC) toward the open estuary. Core profiles of T-Hg and trace metals (Ni, Zn) showed substantial inputs starting in 1905, with peak concentrations between 1960 and 1970's, and decreasing thereafter with exception to Pb, which peaked around 1930-1940s. Stable carbon isotopes and lignin phenols showed an increasing input of terrestrial organic matter driven by urban development within the watershed in the early 1940s. Both the enrichment factor and the geoaccumulation index (I geo ) for T-Hg as a measure of the effectiveness of environmental management practices showed substantial improvements since the 1970s. The natural recovery rate in Galveston Bay since the peak input of T-Hg was non-linear and displayed a slow recovery during the twenty-first century. Copyright © 2018 Elsevier Ltd. All rights reserved.

Analysis of Fluvial Bed Sediments Along the Apalachicola River, Florida through Field Reconnaissance Studies

NASA Astrophysics Data System (ADS)

Passeri, D.; Hagen, S. C.; Daranpob, A.; Smar, D. E.

2011-12-01

River competence is an important parameter in understanding sediment transport in fluvial systems. Competence is defined as the measure of a stream's ability to transport a certain maximum grain size of sediment. Studies have shown that bed sediment particle size in rivers and streams tends to vary spatially along the direction of stream flow. Over a river section several reaches long, variability of sediment particle sizes can be seen, often becoming finer downstream. This phenomenon is attributed to mechanisms such as local control of stream gradient, coarse tributary sediment supply or particle breakdown. Average particle size may also be smaller in tributary sections of rivers due to river morphology. The relationship between river mean velocity and particle size that can be transported has also been explored. The Hjulstrom curve classifies this relationship by relating particle size to velocity, dividing the regions of sedimentation, transportation, and erosion. The curve can also be used to find values such as the critical erosion velocity (the velocity required to transport particles of various sizes in suspension) and settling velocity (the velocity at which particles of a given size become too heavy to be transported and fall out of suspension, consequently causing deposition). The purpose of this research is to explore the principles of river competence through field reconnaissance collection and laboratory analysis of fluvial sediment core samples along the Apalachicola River, FL and its distributaries. Sediment core samples were collected in the wetlands and estuarine regions of the Apalachicola River. Sieve and hydrometer analyses were performed to determine the spatial distribution of particle sizes along the river. An existing high resolution hydrodynamic model of the study domain was used to simulate tides and generate river velocities. The Hjulstrom curve and the generated river velocities were used to define whether sediment was being transported, eroded or deposited at the different locations in the river and its distributaries. Parameters such as critical erosion velocity and settling velocity were also calculated to describe sediment transport along the channel. This research provides a better understanding of the fluvial geomorphic system, particularly sediment transport in channels. It also provides excellent validation data for future sediment transport studies in similar fluvial study domains.

Reconstructing the Holocene depositional environments along the northern coast of Sfax (Tunisia): Mineralogical and sedimentological approaches

NASA Astrophysics Data System (ADS)

Lamourou, Ali; Touir, Jamel; Fagel, Nathalie

2017-05-01

A sedimentological and mineralogical study of sedimentary cores allowed reconstructing the evolution of depositional environments along the Northern coast of Sfax (Tunisia). The aim of this research work is to identify the factors controlling the sedimentation from the Holocene to the Present time. Three 30-m sediment cores collected by drilling at 30 m water depth were analyzed for their color, magnetic susceptibility signal, grain size by laser diffraction, organic matter content by loss of ignition, carbonate content by calcimetry and mineralogy by X-ray diffraction on bulk powder and clay <2 μm. They broadly present the same sedimentological and mineralogical features. Microscopical observations of petrographic slides allowed identifying six main sedimentary facies. Bulk mineralogical assemblages comprised clay minerals, quartz, calcite, gypsum and K-feldspars were examined. Considerable change was observed in the carbonate content that mimicked the bioclaste abundance and diluted the detrital minerals (clay minerals, quartz and feldspars). The gypsum mainly occurred in the lower sedimentary columns (SC12 and SC9) and in the upper/middle of core SC6. The clay fraction was made of a mixture of kaolinite, illite, smectite and palygorskite with no clear variation through core depth. Both grain-size parameters and magnetic susceptibility profile showed a sharp transition in the upper 2-5 m of the sedimentological columns. Coarse, sandy to gravely sediments characterized by a low magnetic susceptibility signal were replaced by fine bioclastic-rich clayey sediments. The analysis of vertical succession of depositional facies revealed a fluvial depositional environment (coastal plain) basically marked by fluvial channels and inundation plains at the bottom of all cores. However, core-top sediments recorded a littoral marine environment with sand depositions rich in gastropods, lamellibranches and algæ. Depositional facies, sedimentological and mineralogical parameters were consistent with a transition from a fluviatile depositional environment with some emersion phases marked by the gypsum precipitation, to a marine littoral environment. Such evolution was accompanied with a relative sea-level rise which flooded the fluvial system at the coastal plain during the Holocene, in agreement with sea-level fluctuations in southeast Tunisia during the Holocene.

Variations in the depths of sulfate-methane transition zone (SMTZ) in UBGH2-6 drilling site in Ulleung Basin, East sea of Korea

NASA Astrophysics Data System (ADS)

Kim, Y.; Chun, J. H.; Bahk, J. J.; Ryu, B. J.; Um, I. K.

2016-12-01

The second Ulleung Basin Gas hydrate Drilling Expedition (UBGH2) was conducted in the Ulleung Basin, East Sea of Korea in 2010. Gas hydrates were observed in depth interval from 140 mbsf (meter below seafloor) to 160 mbsf in core sediment taken from UBGH2-6 drilling site, located in the north-western part of the basin (2,164 m water depth). To characterize the geochemical process for UBGH2-6 core sediments, pore fluid samples and headspace gas samples were extracted from core sediments and analyzed SO42- and CH4 concentrations. Based on SO42- and CH4 concentrations, sulfate-methane transition zone (SMTZ), where SO42- is depleted to zero and CH4 starts to increase was defined at a depth of approximately 6.50 mbsf in 2010. And in order to identify the variations in the depths of SMTZ at UBGH2-6 drilling site since 2010 (UBGH2), whole-round piston cores were collected from UBGH2-6 drilling site from 2013 to 2015. We analyzed SO42- and CH4 concentrations and identified the SMTZ for the last 3 years. The depths of SMTZ for the cores obtained from 2013, 2014 and 2015 are approximately 3.50 mbsf, 5.00 mbsf, and 5.00 mbsf respectively. The analysis results indicate that the SMTZ in 2013, 2014, and 2015 are shallower than the SMTZ of 2010.

Hydrologic, lithologic, and chemical data for sediment in the shallow alluvial aquifer at two sites near Fallon, Churchill County, Nevada, 1984-85

USGS Publications Warehouse

Lico, M.S.; Welch, A.H.; Hughes, J.L.

1986-01-01

The U.S. Geological Survey collected an extensive amount of hydrogeologic data from the shallow alluvial aquifer at two study sites near Fallon, Nevada, from 1984 though 1985. These data were collected as part of a study to determine the geochemical controls on the mobility of arsenic and other trace elements in shallow groundwater systems. The main study area is approximately 7 miles south of Fallon. A subsidiary study area is about 8 miles east of Fallon. The data collected include lithologic logs and water level altitudes for the augered sampling wells and piezometers, and determinations of arsenic and selenium content, grain size, porosity, hydraulic conductivity, and mineralogy for sediment samples from cores. (USGS)

Fish Lake, Utah - a promising long core site straddling the Great Basin to Colorado Plateau transition zone

NASA Astrophysics Data System (ADS)

Marchetti, D. W.; Abbott, M. B.; Bailey, C.; Wenrich, E.; Stoner, J. S.; Larsen, D. J.; Finkenbinder, M. S.; Anderson, L.; Brunelle, A.; Carter, V.; Power, M. J.; Hatfield, R. G.; Reilly, B.; Harris, M. S.; Grimm, E. C.; Donovan, J.

2015-12-01

Fish Lake (~7x1.5 km and 2696 m asl) is located on the Fish Lake Plateau in central Utah. The Lake occupies a NE-striking tectonic graben; one of a suite of grabens on the Plateau that cut 21-26 Ma volcanic rocks. The lake outflows via Lake Creek to the NE where it joins Sevenmile Creek to become the Fremont River, a tributary to the Colorado River. A bathymetric survey reveals a mean depth of 27 m and a max depth of 37.2 m. The lake bottom slopes from NW to SE with the deepest part near the SE wall, matching the topographic expression of the graben. Nearby Fish Lake Hightop (3545 m) was glaciated with an ice field and outlet glaciers. Exposure ages indicate moraine deposition during Pinedale (15-23 ka) and Bull Lake (130-150 ka) times. One outlet glacier at Pelican Canyon deposited moraines and outwash into the lake but the main basin of the lake was never glaciated. Gravity measurements indicate that lake sediments thicken toward the SE side of the lake and the thickest sediment package is modeled to be between 210 and 240 m. In Feb 2014 we collected cores from Fish Lake using a 9-cm diameter UWITECH coring system in 30.5 m of water. A composite 11.2-m-long core was constructed from overlapping 2 m drives that were taken in triplicate to ensure total recovery and good preservation. Twelve 14C ages and 3 tephra layers of known age define the age model. The oldest 14C age of 32.3±4.2 cal ka BP was taken from 10.6 m. Core lithology, CT scans, and magnetic susceptibility (ms) reveal three sediment packages: an organic-rich, low ms Holocene to post-glacial section, a fine-grained, minerogenic glacial section with high ms, and a short section of inferred pre-LGM sediment with intermediate composition. Extrapolating the age model to the maximum estimated sediment thicknesses suggest sediments may be older than 500-700 ka. Thus Fish Lake is an ideal candidate for long core retrieval as it likely contains paleoclimatic records extending over multiple glacial cycles.

Distribution of radionuclides in a marine sediment core off the waterspout of the nuclear power plants in Daya Bay, northeastern South China Sea.

PubMed

Zhou, Peng; Li, Dongmei; Li, Haitao; Fang, Hongda; Huang, Chuguang; Zhang, Yusheng; Zhang, Hongbiao; Zhao, Li; Zhou, Junjie; Wang, Hua; Yang, Jie

2015-07-01

A sediment core was collected and dated using (210)Pbex dating method off the waterspout of nuclear power base of Daya Bay, northeastern South China Sea. The γ-emitting radionuclides were analyzed using HPGe γ spectrometry, gross alpha and beta radioactivity as well as other geochemical indicators were deliberated to assess the impact of nuclear power plants (NPP) operation and to study the past environment changes. It suggested that NPP provided no new radioactivity source to sediment based on the low specific activity of (137)Cs. Two broad peaks of TOC, TC and LOI accorded well with the commercial operations of Daya Bay NPP (1994.2 and 1994.5) and LNPP Phase I (2002.5 and 2003.3), implying that the mass input of cooling water from NPP may result into a substantial change in the ecological environment and Daya Bay has been severely impacted by human activities. Copyright © 2015 Elsevier Ltd. All rights reserved.

Development of recent chronologies and evaluation of temporal variations in Pb fluxes and sources in lake sediment and peat cores in a remote, highly radiogenic environment, Cairngorm Mountains, Scottish Highlands

NASA Astrophysics Data System (ADS)

Farmer, John G.; MacKenzie, Angus B.; Graham, Margaret C.; Macgregor, Kenneth; Kirika, Alexander

2015-05-01

The use of stable Pb isotope analyses in conjunction with recent (210Pb and anthropogenic radionuclide) chronologies has become a well-established method for evaluating historical trends in depositional fluxes and sources of atmospherically deposited Pb using archival records in lake sediment or peat cores. Such studies rely upon (i) simple radioactive disequilibrium between unsupported 210Pb and longer-lived members of the 238U decay series and (ii) well-defined values for the isotopic composition of contaminant Pb and indigenous Pb in the study area. However, areas of high natural radioactivity can present challenging environments for such studies, with potential complications arising from more complex disequilibria in the 238U decay series and the occurrence, at local or regional level, of anomalous, ill-defined stable isotope ratios due to the presence of elevated levels of radiogenic Pb. Results are presented here for a study of a sediment core from a freshwater lake, Loch Einich, in the high natural radioactivity area of the Cairngorm Mountains of Scotland. 238U decay series disequilibria revealed recent diagenetic re-deposition of both U and 226Ra, the latter resulting in a requirement to use a modified calculation to derive a 210Pb chronology for the core. Confidence in the chronology was provided by good agreement with the independent 241Am chronology, but the 137Cs distribution was affected by significant post-depositional mobility in the organic-rich sediment. The systematics of variations in 230Th, 232Th and stable Pb isotope ratio distributions were used to establish the indigenous Pb characteristics of the sediment. The relatively high radiogenic content of the indigenous Pb resulted in complications in source apportionment, in particular during the 20th century, with multiple natural and anthropogenic sources precluding the use of a simple binary mixing model. Consequently, 206Pb/207Pb ratios in Scottish moss samples from an archive collection were used to provide the input term for atmospheric deposition in order to establish historical trends in indigenous and anthropogenic Pb fluxes. A test of the accuracy of the derived Pb fluxes was provided by analysis of a core from a nearby blanket peat deposit, Great Moss. Independent atmospheric and basal inputs gave a complex distribution of 210Pb in the peat, but this did not affect calculation of a 210Pb chronology. Once again, the 210Pb chronology was supported by the 241Am distribution. Temporal trends in anthropogenic Pb deposition derived for the Loch Einich sediment core were in generally good agreement with those for the Great Moss peat core, other peat cores and some other lake sediment cores from northern Scotland, providing confidence in the use of the archive moss data to characterise atmospheric deposition. However, sustained input of Pb to Loch Einich sediment at relatively high levels in the late 20th century, after the regional decline in atmospheric Pb deposition, suggested that catchment-derived Pb is now a significant component of the depositional flux for Loch Einich.

Trawling-induced alterations of deep-sea sediment accumulation rates during the Anthropocene

NASA Astrophysics Data System (ADS)

Puig, P.; Paradis, S.; Masque, P.; Martin, J.; Juan, X.; Palanques, A.

2015-12-01

Commercial bottom trawling causes direct physical disturbance of the marine sedimentary environments by scraping and ploughing the seabed, generating periodic resuspension of surface sediments. However, the quantification of the sediment that is removed by trawling and exported across the continental margin remains largely unaddressed, and the preservation of the signal of such impacts in the geological record have been mostly overlooked. The analysis of sediment cores collected along the Catalan margin (NW Mediterranean) has allowed evaluating the contribution of this anthropogenic activity to the present-day sediment dynamics. Sediment cores at intensively trawled sites are characterized by over-consolidated sediments with lower 210Pb surface concentrations and inventories that indicate widespread erosion of recent sedimentary deposits. In turn, combined 210Pb and 137Cs chronologies indicate a significant increase of sediment accumulation rates within submarine canyon environments since the 1970s, coincidently with a strong impulse in the industrialization of the trawling fleets of this region. Two sampling sites that exhibited high sediment accumulation rates (0.6-0.7 cm/y) were reoccupied 1-2 decades after the first studies and revealed a second and even larger increase of sediment accumulation rates (>2 cm/y) occurring at the beginning of the XXI century. This recent change has been attributed to a preferential displacement of the trawling fleet towards fishing grounds surrounding submarine canyons and, also, to technical improvements in trawling vessels, presumably related to financial subsidies provided to the fishing sector. The alteration of sediment accumulation rates described in this continental margin may occur in many regions of the World's oceans given the wide geographical distribution of this human activity, and therefore, it could represent a potential marker of the Anthropocene in deep-sea environments.

Physical and chemical characteristics including total and geochemical forms of phosphorus in sediment from the top 30 centimeters of cores collected in October 2006 at 26 sites in Upper Klamath Lake, Oregon

USGS Publications Warehouse

Simon, Nancy S.; Ingle, Sarah N.

2011-01-01

μThis study of phosphorus (P) cycling in eutrophic Upper Klamath Lake (UKL), Oregon, was conducted by the U.S. Geological Survey in cooperation with the U.S. Bureau of Reclamation. Lakebed sediments from the upper 30 centimeters (cm) of cores collected from 26 sites were characterized. Cores were sampled at 0.5, 1.5, 2.5, 3.5, 4.5, 10, 15, 20, 25, and 30 cm. Prior to freezing, water content and sediment pH were determined. After being freeze-dried, all samples were separated into greater than 63-micron (μm) particle-size (coarse) and less than 63-μm particle-size (fine) fractions. In the surface samples (0.5 to 4.5 cm below the sediment water interface), approximately three-fourths of the particles were larger than 63-μm. The ratios of the coarse particle-size fraction (>63 μm) and the fine particle-size fraction (<63 μm) were approximately equal in samples at depths greater than 10 cm below the sediment water interface. Chemical analyses included both size fractions of freeze-dried samples. Chemical analyses included determination of total concentrations of aluminum (Al), calcium (Ca), carbon (C), iron (Fe), poorly crystalline Fe, nitrogen (N), P, and titanium (Ti). Total Fe concentrations were the largest in sediment from the northern portion of UKL, Howard Bay, and the southern portion of the lake. Concentrations of total Al, Ca, and Ti were largest in sediment from the northern, central, and southernmost portions of the lake and in sediment from Howard Bay. Concentrations of total C and N were largest in sediment from the embayments and in sediment from the northern arm and southern portion of the lake in the general region of Buck Island. Concentrations of total C were larger in the greater than 63-μm particle-size fraction than in the less than 63-μm particle-size fraction. Sediments were sequentially extracted to determine concentrations of inorganic forms of P, including loosely sorbed P, P associated with poorly crystalline Fe oxides, and P associated with mineral phases. The difference between the concentration of total P and sum of the concentrations of inorganic forms of P is referred to as residual P. Residual P was the largest fraction of P in all of the sediment samples. In UKL, the correlation between concentrations of total P and total Fe in sediment is poor (R2<0.1). The correlation between the concentrations of total P and P associated with poorly crystalline Fe oxides is good (R2=0.43) in surface sediment (0.5-4.5 cm below the sediment water interface) but poor (R2<0.1) in sediments at depths between 10 cm and 30 cm. Phosphorus associated with poorly crystalline Fe oxides is considered bioavailable because it is released when sediment conditions change from oxidizing to reducing, which causes dissolution of Fe oxides.

Characteristics of Holocene sediments in the Gunsan Basin, central Yellow Sea

NASA Astrophysics Data System (ADS)

Woo, H. J.; Huh, S.; Jeong, K. S.; Lee, J. H.; Ham, A.; Kang, J.

2016-12-01

The Gunsan Basin, in the eastern part of the South Yellow Sea Basin, is filled by terrestrial sedimentary rocks, maximally up to 8 km deep on the basement of metamorphic rocks that constitutes the Yangtze Platform. The uppermost sedimentary layer (generally less than 1 km) appears to have formed experiencing the repeated marine environments since the middle Miocene. This study is to investigate the characteristics of Holocene sediments in the Gunsan Basin, based on interpretation of core sediments and high-resolution shallow (Sparker and Chirp) seismic profiles. The surface sediments in the basin consist of sand (56.6% on the average), silt (18.4%), and clay (25.0%) with a mean grain size of 1.5 to 7.8 Ø. Sand is prevalent (63.8 to 98.3%) in and around the Yellow Sea Trough lying in the eastern part of the basin. The sandy sediments are regarded as relict sediments deposited in the last glacial maximum (LGM). The sedimentary environments are classified, based on the acoustic and morphological characters of high-resolution shallow (Sparker and Chirp) seismic profiles, into mud zone, deformed zone, and sand ridges with sand waves zone from the west to the east in the Gunsan Basin. The deformed zone in the central Yellow Sea is a mixing area of sediments derived from China and Korea, where there are a number of paleochannels and erosional surfaces in the direction of northwest-southeast. The deformed zone represents non-deposition or erosion in the central Yellow Sea during the Holocene. Tidal sand ridges and sand waves are well developed along the coast of Korea. Modern sand ridges are generally moving in the northeast-southwest direction, which coincide with dominant tidal current direction. Fifteen piston cores were collected in the basin to investigate the general geological characters of the marine sedimentary sequence. In comparison with three cores in the southern basin, the sand contents tend to increase in the direction of east. 14C dates from three cores near border of Exclusive Economic Zone (EEZ) of Korea reveal that Holocene sediments have accumulated at the rate 6-18 cm/ka. The mud sediments sequentially change sandy mud to mud after the sea-level rise. In the Gunsan Basin, paleochannels played an important role in sedimentary processes during low sea-level periods of Quaternary.

Is the core top modern? Observations from the eastern equatorial Pacific

NASA Astrophysics Data System (ADS)

Mekik, Figen; Anderson, Robert

2018-04-01

A compilation of ages from 67 core tops in the eastern equatorial Pacific (EEP) does not display an easily discernible regional pattern. The ages range from 790 to over 15,000 years. The youngest core tops with the highest sediment focusing factors are located in the Panama Basin. There are weak but statistically significant inverse relationships between core top age and age-model based mass accumulation rates, bioturbation depth, linear sedimentation rate and sediment focusing factors. However, we found no statistically significant relationship between core top age and calcite dissolution in sediments or 230Th-normalized mass accumulation rates. We found evidence suggesting that greater amount of sediment focusing helps to preserve the carbonate fraction of the sediment where focusing is taking place. When focusing factors are plotted against percent calcite dissolved, we observe a strong inverse relationship, and core tops younger than 4500 years tend to occur where focusing factors are high and percent calcite dissolved values are low. Using labile organic carbon fluxes to estimate bioturbation depth in the sediments results in the observation that where bioturbation depth is shallow (<4 cm), the core top age has a strong, inverse relationship with sediment accumulation rate. We used the Globorotalia menardii Fragmentation Index (MFI) as an indicator of percent calcite dissolved in deep sea sediments. There is a distinct pattern to core top calcite dissolution in the EEP which delineates bands of high surface ocean productivity as well as the clear increase in dissolution downward on the flanks of the East Pacific Rise.

An ultra-high resolution last deglacial marine sediment records of the Northwest Atlantic Ocean

NASA Astrophysics Data System (ADS)

Rashid, H.; Piper, D.; Marche, B.; Vermooten, M.; Lazar, K.; Brockway, B.

2016-12-01

Lack of high sedimentation rate records of past changes pertaining to the late Pleistocene Laurentide ice-sheet (LIS) dynamics has prevented efforts to differentiate the various forcings in modulating abrupt climate changes. Here, we present an ultra-high resolution sediment record spanning approximately 1,500 km of the Eastern Canadian continental margin. The new record comprises four sediment cores which were collected from the northwest Labrador Sea (i.e., Saglek Bank) to southwestern Flemish Pass to the southeast Grand Banks in outer shelf and slope settings. Fifty new 14C-accelerator mass spectrometric dates were obtained to construct the stratigraphy. The total sediment thickness of the new record is 41 m covering the past 26 ka with 1.58/ka mean sediment rate, the highest sediment rate ever reported from the Northwest Atlantic Ocean for this time interval. Further, the temporal resolution of the record varies from a couple of decades to centuries depending on the time interval. X-ray fluorescence (XRF) data in conjunction with physical properties of sediments and petrology allowed us to distinguish sediment delivered by major ice-streams of the LIS namely the Hudson Strait, Hopedale Saddle, and Cumberland Sound ice streams. Heinrich layers 1 and 2 are well identified by their Labrador Sea specific characteristics. The so-called Younger Dryas equivalent Heinrich layer H0 was identified in these cores but the timing of onset of H0 has an offset by nearly 1,000 years with that of the 12.9 ka, suggesting that the YD event was not initiated by the Hudson Strait compared to other Heinrich events.

Paleoseismic events inferred from marine seismogenic turbidites of the eastern Nankai Trough

NASA Astrophysics Data System (ADS)

Okutsu, N.; Ashi, J.; Omura, A.; Yamaguchi, A.; Suganuma, Y.; Kanamatsu, T.; Murayama, M.

2016-12-01

Paleoseismology using marine seismogenic turbidites is a developing field especially in subduction margins. However, very fine-grained turbidites are difficult to distinguish from hemipelagic mud. The primary focus of this study is to understand the characteristics of the muddy turbidites. The second focus is to discuss the muddy turbidites distributions and their ages from a longer sediment core, and understand the paleoseismic records of eastern Nankai Trough, Japan. The samples used in this study include multiple cores and a piston core which were collected from the sedimentary basin southwest off Kii Peninsula during the R/V Shinsei Maru KS-14-8 cruise. The sampling site is located at the ENE-WSW elongated basin between the accretionary prism and the forearc basin off Kumano without terrestrial sediment supply. The basin exhibits a terminal basin that captures all sediments supplied from outside. From the multiple core samples, the Cs-137 and Pb- 210 concentration distribution indicates that the muddy sediment layer in the upper 17 cm was formed from the 2004 off the Kii Peninsula earthquake. Visual observation and X-ray CT scans were conducted alongside other measurements for anisotropy of magnetic susceptibility (AMS), paleomagnetism, rock magnetism, electrical resistivity, and X-ray fluorescence core scanning (XRF). Muddy seismogenic turbidites associated with the 2004 off the Kii Peninsula earthquake have thick homogeneous clay layer above the silty lamination. The magnetic susceptibility decreases upwards in the lamination. This specific feature is thought to have formed as the muddy turbiditity current slowly decelerated and slowly settled down the slope. From the results of XRF core scanning, Ca and Fe have a peak at basement of turbidites, and decrease upwards. Ca is thought to correspond to amount of the foraminiferas. In piston core, we observed the same sedimentary and magnetic characteristics as the multiple cores. Based on stratigraphic information from volcanic ash and radiocarbon age of the foraminifera, intercalation pattern of muddy turbidite layers almost consistent with the known past earthquake recurrence times in the Nankai subduction margin. Reversed age recognized beneath the thick turbidite layer suggests reworking of landslide deposits probably due to the strong shaking.

Quantifying grain shape with MorpheoLV: A case study using Holocene glacial marine sediments

NASA Astrophysics Data System (ADS)

Charpentier, Isabelle; Staszyc, Alicia B.; Wellner, Julia S.; Alejandro, Vanessa

2017-06-01

As demonstrated in earlier works, quantitative grain shape analysis has revealed to be a strong proxy for determining sediment transport history and depositional environments. MorpheoLV, devoted to the calculation of roughness coefficients from pictures of unique clastic sediment grains using Fourier analysis, drives computations for a collection of samples of grain images. This process may be applied to sedimentary deposits assuming core/interval/image archives for the storage of samples collected along depth. This study uses a 25.8 m jumbo piston core, NBP1203 JPC36, taken from a 100 m thick sedimentary drift deposit from Perseverance Drift on the northern Antarctic Peninsula continental shelf. Changes in ocean and ice conditions throughout the Holocene recorded in this sedimentary archive can be assessed by studying grain shape, grain texture, and other proxies. Ninety six intervals were sampled and a total of 2319 individual particle images were used. Microtextures of individual grains observed by SEM show a very high abundance of authigenically precipitated silica that obscures the original grain shape. Grain roughness, computed along depth with MorpheoLV, only shows small variation confirming the qualitative observation deduced from the SEM. Despite this, trends can be seen confirming the reliability of MorpheoLV as a tool for quantitative grain shape analysis.

Sediment studies in the Assabet River, central Massachusetts, 2003

USGS Publications Warehouse

Zimmerman, Marc J.; Sorenson, Jason R.

2005-01-01

From its headwaters in Westborough, Massachusetts, to its confluence with the Sudbury River, the 53-kilometer-long Assabet River passes through a series of small towns and mixed land-use areas. Along the way, wastewater-treatment plants release nutrient-rich effluents that contribute to the eutrophic state of this waterway. This condition is most obvious where the river is impounded by a series of dams that have sequestered large amounts of sediment and support rooted and floating macrophytes and epiphytic algae. The water in parts of these impoundments may also have low concentrations of dissolved oxygen, another symptom of eutrophication. All of the impoundments had relatively shallow maximum water depths, which ranged from approximately 2.4 to 3.4 meters, and all had extensive shallow areas. Sediment volumes estimated for the six impoundments ranged from approximately 380 cubic meters in the Aluminum City impoundment to 580,000 cubic meters in the Ben Smith impoundment. The other impoundments had sediment volumes of 120,000 cubic meters (Powdermill), 67,000 cubic meters (Gleasondale), 55,000 cubic meters (Hudson), and 42,000 cubic meters (Allen Street). The principal objective of this study was the determination of sediment volume, extent, and chemistry, in particular, the characterization of toxic inorganic and organic chemicals in the sediments. To determine the bulk-sediment chemical-constituent concentrations, more than one hundred sediment cores were collected in pairs from the six impoundments. One core from each pair was sampled for inorganic constituents and the other for organic constituents. Most of the cores analyzed for inorganics were sectioned to provide information on the vertical distribution of analytes; a subset of the cores analyzed for organics was also sectioned. Approximately 200 samples were analyzed for inorganic constituents and 100 for organics; more than 10 percent were quality-control replicate or blank samples. Maximum bulk-sediment phosphorus concentrations in surface samples from the impoundments increased along a downstream gradient, with the exception of samples from the last impoundment, where the concentrations decreased. In addition, the highest phosphorus concentrations were generally in the surface samples; this finding may prove helpful if surface dredging is selected as a means to control phosphorus release from sediments. There is no known relation, however, between bulk-sediment concentration of phosphorus and the concentrations of phosphorus available to biota. Potentially toxic metals, including arsenic, cadmium, chromium, copper, nickel, lead, and zinc were frequently measured at concentrations that exceeded U.S. Environmental Protection Agency sediment-quality guidelines for the protection of aquatic life and that occasionally exceeded Massachusetts Department of Environmental Protection guidelines governing landfill disposal (reuse). Due to the effects of matrix interference and sample dilution on laboratory analyses, neither pesticides nor volatile organic compounds were detected at any sites. However, samples collected in other studies from nearby streams indicated the possibility that pesticides might have been detected in the impoundments if not for these analytical problems. Although polychlorinated biphenyl concentrations, as individual Aroclors, generally exceeded published U.S. Environmental Protection Agency guideline concentrations for potential effects on aquatic life, the U.S. Environmental Protection Agency guideline concentrations for human contact or the Massachusetts guidelines for landfill reuse were rarely exceeded. Concentrations of polycyclic aromatic hydrocarbons, both individually and total, frequently were greater than guideline concentrations. Concentrations of total extractable petroleum hydrocarbons did not exceed Massachusetts guideline concentrations in any samples. When the sediment analytes from surface samples are considered togethe

Precipitation of ikaite crystals in Antarctic marine sediments: implications from pore water geochemistry

NASA Astrophysics Data System (ADS)

Lu, Z.; Kennedy, H.; Rickaby, R. E.; Georg, B.; Shaw, S.; Lennie, A.; Pancost, R. D.

2008-12-01

Ikaite is a calcium carbonate hexahydrate (CaCO3•6H20) considered to be stable only at low temperatures. It has been found in form of tufa tower at locations where alkaline water mixes with water masses enriched in calcium (e.g. Ikka Fjord, Mono Lake). Large euhedral single crystals of ikaite were also recovered in marine sediments, associated with organic matter degradation, anaerobic oxidation of methane (AOM) and sulfate reduction. The hydration water in the ikaite crystals were demonstrated to record the oxygen isotope composition of the water from which they precipitated. Such a characteristic may allow using ikaite to reconstruct the ice volume in the past. For this purpose, the controls on its precipitation in the sediment column need to be investigated which is the main goal of this study. U.S. Antarctica Program cruise NBP0703 collected two cores with ikaite crystals at Antarctica Peninsula (Bransfield Strait and Firth of Tay). We determined major cation/anion concentrations, dissolved inorganic carbon (DIC) and δ13C composition of DIC in the pore waters in these two cores. Strong organic matter degradation or AOM in both cores results in quick consumption of sulfate in shallow part of the cores (SMT at around 3m).Rapid build-up of DIC is accompanied by the sharp decrease of dissolved calcium in the top 5m. Large variations were observed in δ13CDIC values (-20‰ to +13‰). The δ13C of ikaite in two cores were distinctive from each other (-19‰ and +4‰) corresponding to the DIC pools at different depths. The down core saturation state of the ikaite was modeled in PHREEQC based on the pore water chemistry, and the results are consistent with carbon isotope data, suggesting that these large crystals very likely formed within a narrow depth interval and a short time period (given high sedimentation rates of 0.5-1 cm/yr in this area).

Changes in Holocene to LGM water mass stratification near Southern Africa inferred from Nd isotopes

NASA Astrophysics Data System (ADS)

Jones, K. M.; Goldstein, S. L.; Hemming, S. R.; Hall, I. R.; Zahn, R.

2009-12-01

Global thermohaline circulation (THC) is an important component of the climate system that initiates or amplifies abrupt climate change. A major driver of THC is the formation of North Atlantic Deep Water (NADW), which is sandwiched by northward flowing Southern Ocean water masses as it is advected southward. An important exit route of NADW out of the South Atlantic is through flow around the southern tip of Africa, which makes the South African Margin an excellent location to investigate changes in THC and water mass stratification through time. We measured the Nd isotopes of modern seawater from three depth profiles collected along the South African Margin, which were collected on RSS Charles Darwin Cruise 154. All seawater profiles show a similar pattern with higher ɛNd values at intermediate depths (ɛNd ~ -9.5 at 600-1200m), lower values for the core of NADW (ɛNd ~ -11.5 at 2000-3500m), and higher values in the deepest waters sampled (ɛNd -9.8 at 4150m). This pattern is consistent with conservative mixing of major North Atlantic and Southern Ocean end-member water masses and is not consistent with inputs from, or exchange with margin sediments, for most depths. We also measured the Nd isotopes of multiple sedimentary archives in proximal Holocene coretop sediments collected from depths spanning intermediate to deep/bottom waters. The Nd isotopes of a fish tooth, several foram coating leachates, and multiple bulk sediment Fe-Mn leachates display the same pattern as the local seawater. We had no seawater for comparison with our deepest core (VM19-224; depth ~ 4600m), but the eNd value from it (ɛNd = -8.4) is consistent with Antarctic Bottom Water (ɛNd ~ -8.5). These results suggest: (1) that Nd isotopes of seawater in the region behave conservatively; (2) that the local margin sediments faithfully record the Nd isotope composition of the waters they are bathed in and (3) this “ground-truthing” implies that it is valid to use Nd isotopes as a circulation proxy in this region to reconstruct THC and water mass stratification along this margin through time. Nd isotopes were also measured on bulk sediment and foram coating Fe-Mn leachates of radiocarbon dated LGM sediments. The leachate Nd isotope composition of the deepest sample (VM19-224; ɛNd = -7.0) is within error of LGM samples from RC11-83 in the Cape Basin (depth ~ 4700m; ɛNd = -6.6). Cores from shallower depths (2800 to 3600m) are also offset toward higher higher ɛNd consistent with weaker NADW. The shallowest core (VM14-77; depth ~ 1800m) displays an opposite shift from higher values in the Holocene (ɛNd = -9.9) to lower values during the LGM (ɛNd = -12.0). However, this core is in the region of the Tugela River Cone and may be impacted by that river. These data are consistent with a significant reduction of NADW export to the Southern Ocean during the LGM but the LGM value of the shallowest core is also consistent with the shoaling of NADW during this time interval as it continued to flow out of the Atlantic.

Characterization and Modeling of Settling, Consolidation, and Suspension to Optimize Sediment Retention of Sediment Diversions for Coastal Restoration

NASA Astrophysics Data System (ADS)

Sha, X.; Xu, K.; Bentley, S. J.; Robichaux, P.

2016-02-01

Although many studies of sediment diversions have been conducted on the Mississippi Delta, relatively less attention has been paid to understanding sediment retention and basic cohesive sedimentation processes in receiving basins. Our research evaluates long-term (up to six months) sedimentation processes through various laboratory experiments, especially cohesive sediment settling, consolidation and resuspension and their impacts on sediment retention. Bulk sediment samples were collected from West Bay, near Head of Passes of the Mississippi Delta, and the Big Mar basin that receive water and sediment from the Caernarvon Diversion in the upper Breton Sound region of Louisiana, USA. A-230-cm tall settling column with nine sampling ports at 15 cm intervals was used to measure the consolidation for four initial sediment concentrations (10-120 kg m-3) with two salinities (1 ppt & 5 ppt). Samples of sediment slurry were taken from every port at different time intervals up to 15 days or longer (higher concentration needs longer time to consolidate) to record concentrations gravimetrically. A 200 cm long tube was connected to a 50 cm long core chamber to accumulate at least a 10 cm thick sediment column for erosion tests. A dual-core Gust Erosion Microcosm System was employed to measure time-series (0.5, 1, 2, 3, 4, 5, 6 months) erodibility at seven shear stress regimes (0.01-0.60 Pa). Our preliminary results show a significant decrease of erodibility with time and high concentration (120g/L). Salinity impacted on sediment behavior in consolidation experiments. Our study reveals that more enclosed receiving basins, intermittent openings of diversions, or reduced shear stress due to man-made structure all can potentially reduce cohesive sediment erosion in coastal Louisiana. Further results will be analyzed to determine the model constants. Consolidating rates and corresponding erosional changes will be determined to optimize sediment retention in coastal protection.

Contaminant trends in reservoir sediment cores as records of influent stream quality

USGS Publications Warehouse

Van Metre, P.C.; Mahler, B.J.

2004-01-01

When reconstructing water-quality histories from lake and reservoir cores, it is sometimes assumed that the chemical signatures in the cores reflect historical water quality in the influent streams. To investigate this assumption, concentrations of metals, PAHs, and organochlorine compounds in sediment cores were compared to those associated with an influent-stream suspended sediment for three reservoirs in Fort Worth, TX, and two reservoirs in Boston, MA, U.S.A., and interpreted in light of land-use and regulation histories. In evaluating relations between suspended sediments and cores, three levels of preservation were indicated: (1) influent concentrations and historical trends are preserved in cores (metals at all sites; some organic contaminants at some sites); (2) some loss occurs during transport and initial deposition but relative historical trends are preserved in cores (some organic contaminants at some sites); and (3) neither stream concentrations nor relative historical trends are preserved (dieldrin and p,p???-DDT). The degree of preservation of influent concentration histories varied between lakes, particularly for PAHs. The results support the use of sediment cores to infer streamwater-quality histories for many contaminants but indicate that reservoir-bottom sediment samples might underestimate concentrations of organic contaminants in some streams.

Tritium, deuterium, and oxygen-18 in water collected from unsaturated sediments near a low-level radioactive-waste burial site south of Beatty, Nevada

USGS Publications Warehouse

Prudic, David E.; Stonestrom, David A.; Striegl, Robert G.

1997-01-01

Pore water was extracted in March 1996 from cores collected from test holes UZB-1 and UZB-2 drilled November 1992 and September 1993, respectively, in the Amargosa Desert south of Beatty, Nevada. The test holes are part of a study to determine factors affecting water and gas movement through unsaturated sediments. The holes are about 100 meters south of the southwest corner of the fence enclosing a commercial burial area for low-level radioactive waste. Water vapor collected from test hole UZB-2 in April 1994 and July 1995 had tritium concentrations greater than would be expected from atmospheric deposition. An apparatus was built in which pore water was extracted by cryodistillation from the previously obtained core samples. The extracted core water was analyzed for the radioactive isotope tritium and for the stable isotopes deuterium (D) and oxygen-18 (18O). The isotopic composition of core water was compared with that of water vapor previously collected from air ports in test hole UZB-2 and to additional samples collected during May 1996. Core water becomes increasingly depleted in D and 18O from the land surface to a depth of 30 meters, indicating that net evaporation of water is occurring near the land surface. Below a depth of 30 meters the stable-isotopic composition of core water becomes nearly constant and roughly equal to that of ground water. The stable isotopes plot on an evaporation trend. The source of the partly evaporated water could be either ground water or past precipitation having the same average isotopic composition as ground water but not modern precipitation, based on 18 months of record. Profiles of D and 18O in water vapor roughly parallel those in core water. The stable isotopes of core water appear to be in isotopic equilibrium with water vapor from UZB-2 when temperature-dependent fractionation is considered. The data are consistent with the hypothesis of evaporative discharge of ground water at the land surface. The concentration of tritium in core water from depths less than 50 meters was higher than that of present-day atmospheric air, indicating that elevated tritium concentrations preceded the drilling. The concentrations of tritium in core water from the deepest sample (85 meters) and in UZB-2 groundwater (110 meters) were below detection. Thus, tritium in the unsaturated zone is not being introduced through ground water. The shape of the tritium profile for core water was similar to the shape of the tritium profile for water vapor collected April 1994, except that concentrations were consistently lower in core water than in water vapor. Tritium concentrations in water vapor increased from April 1994 to May 1996. Similar to the stable isotopes, the highest tritium concentrations were measured at shallow depths. Concentrations of tritium in water vapor during core collection were estimated assuming isotopic equilibrium with core water. The computed concentrations for November 1992 and September 1993 form consistent temporal trends with subsequent tritium concentrations in water vapor collected April 1994, July 1995, and May 1996. Observations of a bimodal distribution of tritium, in which the highest concentrations are in a gravel layer at a depth of 1-2 meters, indicate lateral migration of tritium through the vicinity of UZB-2.

Temporal Trends of Triclosan in Sediment Cores Collected from Two Urbanized Estuaries

EPA Science Inventory

Triclosan (5-chloro-2-(2,4-dichlorophenoxy)-phenol) is a antimicrobial agent present in a wide array of consumer based goods such as soaps, skin creams and dental care products. It has also been incorporated into consumer textiles and plastics due to its effectiveness as a bioci...

IN-SITU REMEDIATION OF CHROMIUM-CONTAMINATED SOILS AND SEDIMENTS USING SODIUM DITHIONITE

EPA Science Inventory

Soil cores were collected from beneath an old chrome plating shop at the USCG Support Center near Elizabeth City, NC in order to determine the extent of chromium contamination in the soils and ground water. Selective extractions were used to assess the chemical speciation and di...

CERC Field Research Facility Environmental Data Summary, 1977-79.

DTIC Science & Technology

1982-12-01

Motorola "Mini-Ranger," coupled to a Hewlett-Packard Mini-Computer and flatbed plotter. This positioning system was put together and operated by Prank... laminations within the core. While one diver collected the sample, the second diver recorded conditions on the bottom. This description included sediment

Total mercury concentration in sediment from the continental shelf of central California

NASA Astrophysics Data System (ADS)

Acosta, R. M.; Weiss-Penzias, P. S.; Bauer, V.; Ryan, J. P.; Flegal, A. R.

2012-12-01

In order to understand the biogeochemical distribution of mercury (Hg) and locate specific Hg hot spots in the coastal region of central California, total mercury (HgT) concentration were measured in 43 archived sediment cores collected between Año Nuevo and the southern end of Monterey Bay. The samples were taken from USGS in Menlo Park, California on May 4th 2012. The cores were collected through the Environmental Management Assessment Program (EMAP), with ID sites: M-1-95-MB, P-2-95-MB and P-1-97-MB. For the purpose of this study we assumed that there has been negligible diagenesis on trace metal Hg since samples were taken. Total Hg concentrations were measured on the top five cm of the cores and yielded a mean of 0.037 μg g-1, and ranged from 0.013 to 0.113 μg g-1. In addition, the 43 samples were split into nine transects, and transects found near the mouth of Monterey Bay submarine canyon (MBSC) contained the highest concentration of HgT, with a mean concentration of 0.043 μg g-1, and ranged from 0.038 to 0.113 μg g-1. This substantial increase in HgT concentration near MBSC might be a product of the bathymetry acting as a sink or interaction between internal waves and the canyon's rim. This allows reactivation of surface sediment, which can separate fine grained sand, mud and clay content near the mid-shelf region and the canyon rim. Three depth profiles with 0-30 cm intervals were measured for HgT concentrations. Cores averaged mean HgT concentrations of 0.032, 0.040, and 0.037 μg g-1, while each profile ranged from 0.025-0.043, 0.028-0.065 and 0.022-0.051 μg g-1. Each depth profile had slight variations in HgT concentrations. One core located between Daven Port and Santa Cruz displayed decreasing HgT concentration with increasing depth. The inconsistency seen in the depth profiles might be products of external factors such as textural changes as depth increases, changes in Hg fluxes, bio mixing, and diagenesis such as redox reactions. Furthermore, comparisons of our data with sedimentation rates found in Monterey Bay have shown mercury concentration in the sediment not influenced by sedimentation rates. Instead, we observed decrease in mud content corresponded to decrease in HgT concentrations; perhaps supporting Hg's strong correlation to organic matter. Although, the sediment Hg concentration in the coastal regions of Monterey Bay, was substantially lower than those found in San Francisco Bay, the data found in this study is conclusive that the hot spots found near MBSC could be an overlooked source of Hg in coastal environments and needs further investigation.

Ground-truthing the Foraminifera-bound Nitrogen Isotope Paleo-proxy in the Modern Sargasso Sea

NASA Astrophysics Data System (ADS)

Smart, S.; Ren, H. A.; Fawcett, S. E.; Conte, M. H.; Rafter, P. A.; Ellis, K. K.; Weigand, M. A.; Sigman, D. M.

2016-02-01

We present the nitrogen isotope ratios (δ15N) of planktonic foraminifera, a type of calcifying zooplankton, collected from surface ocean net tows, moored sediment traps and core-top sediments at the Bermuda Atlantic Time-series Study site in the Sargasso Sea between 2009 and 2013. Consistent with previous measurements from low-latitude core-top sediments, the annually averaged δ15N of organic matter bound within the shells of euphotic zone-dwelling foraminifera approximates that of thermocline nitrate, the dominant source of new nitrogen to Sargasso Sea surface waters. Based on net tow collections in the upper 200 m of the water column, we observe no systematic difference between the biomass δ15N and shell-bound δ15N of a given foraminifera species. For multiple species, the δ15N of net tow-collected upper ocean shells is lower than shells from sediment traps (by 0.5-2.1‰) and lower than shells from seafloor sediments (by 0.5-1.4‰). We are currently investigating whether these differences reflect actual processes affecting shell-bound δ15N or instead relate to the different time periods over which the three sample types integrate. The foraminiferal biomass δ15N time-series from the surface Sargasso Sea exhibits significant seasonal variations, with the lowest values in fall and the highest values in spring. The roles of hydrography, biogeochemistry, and ecosystem dynamics in driving these seasonal variations will be discussed. These data from the modern subtropical ocean form part of a greater effort to ground-truth the use of foram-bound δ15N to reconstruct past nutrient conditions, not only as a recorder of the isotopic composition of nitrogen supply in oligotrophic environments but also as a recorder of the degree of nitrate consumption in high-latitude regions such as the Southern Ocean.

High-resolution sedimentary effects of post-Little Ice Age glacial recession in Hornsund (Svalbard) - insights from chirp and core data

NASA Astrophysics Data System (ADS)

Dominiczak, Aleksander; Szczuciński, Witold; Moskalik, Mateusz; Forwick, Matthias

2017-04-01

As a result of global warming from the end of the Little Ice Age a fast withdrawal and loss of mass of many glaciers have been observed. The retreat has been particularly rapid in case of tidewater glaciers of Spitsbergen, where in an effect a new bays were formed and serve as glaciomarine sediment accumulation areas. The new depocenters in emerging bays are characterized by high sediment accumulation rates. Analysis and quantitative assessment of the processes occurring in these bays can enhance a better understanding of the dynamics of glaciers recession and bio-geochemical processes occurring in the fjords. This is particularly important because the subpolar fjords may be important storage for organic carbon on a global scale (Smith at al. 2015). In order to obtain a detailed high-resolution record of sedimentation history in the post Little Ice Age bays, 30 gravity cores and 18 box cores were collected along with detail seism acoustic surveys (Chirp) during three cruises on board of R/V Helmar Hansen in 2007, 2014 and 2015. The sediment cores revealed two major types of sediments: subglacial till and overlying laminated glacimarine mud with abundant ice rafted debris. The sediment accumulation rate of the latter is estimated to be on average in order of 1 to 5 cm per year. The periods of increase ice rafting are likely related to surge events. The dense Chirp survey grid spatial changeability in the post-Little Ice Age sediment cover. The amount and lithology of sediments in different parts of the bays also helped to link glacier dynamics with sedimentary effect. Our results confirms that despite similarities in lithology there are significant differences in sediment accumulation rates, probably driven by changes in accommodation spaces and sediment delivery. The record is also affected by effects of glacier surges. However, analyses of historical data enhanced the interpretation of sedimentary record and provide hints to identify the specific processes and events in the sedimentary record. The study was funded by Polish National Science Centre grant No. 2013/10/E/ST10/00166. We kindly acknowledge help of the captain and crew of R/V Helmer Hanssen as well as onboard scientific party. Smith, R. W., Bianchi, T. S., Allison, M., Savage, C., & Galy, V. (2015). High rates of organic carbon burial in fjord sediments globally. Nature Geoscience, 8(6), 450-453.

Temporal shifts in reef lagoon sediment composition, Discovery Bay, Jamaica

NASA Astrophysics Data System (ADS)

Perry, Christopher T.; Taylor, Kevin G.; Machent, Philip G.

2006-03-01

Discovery Bay, north Jamaica, forms a large (1.5 km wide), deep (up to 56 m) embayment that acts as a sink for reef-derived and lagoonal carbonate sediments. Since the mid-1960s, the bay has also provided a sink for inputs of bauxite sediment that are spilled during loading at a boat terminal constructed within Discovery Bay. Bauxite has accumulated across much of the southern section of the bay with surficial sediments presently composed of up to 35 weight% non-carbonate. Cores recovered from sites on the western side of the bay provide a stratigraphic record of this history of bauxite contamination across water depths from 5 to 25 m. The bauxite-influenced upper sediment horizons are clearly visible in each core from the distinctive red-brown colouration of the sediment. These sediments are composed of approximately 10% non-carbonate (bauxite) and have Fe contents of around 2-3000 μg/g (up to 7000 μg/g). The thickness of this upper bauxite-contaminated sequence increases down transect (approximately 18 cm in the shallowest core, to around 47 cm in the deepest core), and in each core overlies a sequence of 'clean' lagoon carbonates. These typically are poorly sorted carbonate sands with variable amounts of coral rubble. Down-core data on CaCO 3 and Fe content provide a chemical record of decreasing sediment contamination with depth, with the lower 'clean' carbonates composed of only around 2% non-carbonate and <700 μg/g Fe. Down-core sediment-constituent data also indicate significant changes in sediment production at the shallowest sites. At depths of 5 and 10 m, sediment assemblages have shifted from diverse assemblages of coral, mollusc, Amphiroa and Halimeda in the clean lagoon sands, to assemblages dominated by Halimeda and Amphiroa within the surficial sediments. At the deeper sites, no major down-core shifts in sediment constituents occur. These sites thus record a rather complex history of changes in sediment composition and chemistry. Clear shifts in chemistry and stratigraphy occur in all the cores and reflect progressive bauxite contamination in the near-surface horizons. These inputs, however, do not appear to have directly affected carbonate production, since the major constituent changes appear to be a response to more regional declines in coral community and reef status.

Earthquake Signatures in the Modern Sediment Record of Prince William Sound, Alaska

NASA Astrophysics Data System (ADS)

Marshall, N. R.; Kuehl, S. A.; Dellapenna, T. M.; Miller, E. J.

2016-02-01

Geochemical signatures of earthquake-generated sediment gravity flows are investigated using X-ray fluorescence core scanning on a suite of sediment cores from Prince William Sound, Alaska. This study focused on the development of geochemical proxies for earthquake deposits with an emphasis on interpreting deposits initiated from large subduction earthquakes. A north-south transect of sediment cores from Prince William Sound, between Hinchinbrook Island and the Columbia Glacier, was used to examine a record of earthquakes in this tectonically active region for the past century. The sediments in Prince William Sound are sourced from two geologically distinct regions: the metamorphosed turbidites of coastal Prince William Sound, and the Copper River Basin that contains a significant amount of volcanic rocks. Geochemical studies of sediment cores and end-member sediment samples using X-ray fluorescence and inductively coupled plasma mass spectrometry allowed for the development of geochemical proxies for sediment provenance during the past 100 years. Downcore peaks in Sr/Pb are indicative of Copper River Basin sediments, whereas peaks in K/Ca are indicative of inputs of Prince William Sound sediments. Large subduction earthquakes in northern Prince William Sound initiate gravity flows of Prince William Sound provenance into the deep channel. Particularly robust provenance signatures are seen in the northernmost cores in the core transect, which are closer to the earthquake epicenters and the Columbia Glacier source region. The ages of the deposits, from core-averaged 210Pb sediment accumulation rates, correspond to large earthquakes that occurred in 1912, 1964, and 1983. A similar deposit from 1895 in northern Prince William Sound, prior to historical earthquake records, may have also been initiated from a large earthquake in the 1890's.

INNOVATIVE TECHNOLOGY EVALUATION REPORT, SEDIMENT SAMPLING TECHNOLOGY, ART'S MANUFACTURING, SPLIT CORE SAMPLER FOR SUBMERGED SEDIMENTS

EPA Science Inventory

The Split Core Sampler for Submerged Sediments (Split Core Sampler) designed and fabricated by Arts Manufacturing & Supply, Inc., was demonstrated under the U.S. Environmental Protection Agency (EPA) Superfund Innovative Technology Evaluation Program in April and May 1999 at ...

Sediment Core Descriptions: R/V KANA KEOKI 1972 Cruise, Eastern and Western Pacific Ocean,

DTIC Science & Technology

1976-06-01

of ship tracks and coring stations are shown. Corrected satellite navigation-determined coordinates for each coring operation are indicated, and water depth, length of core, and age of oldest sediment in the cores are given.

Relationship between catchment events (earthquake and heavy rain) and sediment core analysis result in Taiwan.

NASA Astrophysics Data System (ADS)

Chen, Hsin-Ying; Lin, Jiun-Chuan

2015-04-01

Lake sediments contains material from the catchment. In those sediments, there are some features which can indicate characteristic or status of the catchment. These features were formed by different mechanisms, including some events like earthquakes or heavy rain, which are very common in Taiwan. By analyzing and discussing features of sediments there is a chance to identify historical events and rebuild catchment history. In this study, we compare features of sediment core ( including density, mineral grain size, whole grain size, and biogenic silica content) and earthquake, precipitation records. Sediment cores are collected from Emerald peak lake (24.514980, 121.605844; 77.5, 77.2, 64cm depth), Liyutan lake (23.959878, 120.996585; 43.2, 78.1 cm depth), Sun Moon Lake (23.847043, 120.909869; 181 cm depth), and Dongyuan lake (22.205742, 120.854984; 45.1, 44.2cm depth) in 2014. We assume that there are regular material and organic output in catchments. And rain will provide impetus to move material into lakes. The greater the rain is the larger the material can move. So, if there is a heavy rainfall event, grain size of lake sediment may increase. However, when earthquakes happen, it will produce more material which have lower organic composition than ordinary. So we suggest that after earthquakes there will be more material stored in catchment than often. And rainfall event provides power to move material into lakes, cause more sediment and mineral content higher than usual. Comparing with earthquake record(from 1949, by USGS) and precipitation record(from1940, by Central Weather Bureau,Taiwan), there were few earthquakes which happened near lakes and scale were more than 7 ML. There were 28 rainfall events near Emerald peak lake; 32 near Liyutan lake and Sun Moon Lake; 58 near Dongyuan lake ( rainfall event: >250 mm/day ). In sediment analytical results, ratio of whole and mineral grain size indeed have similar trends with earthquake record. However, rainfall events were too frequent to determine the relation between rainfall events and sediment analyze results, that may be obstruction of attempt to speculate the extent of earthquake events.

Patterns and Sources of Sediment and Particulate Organic Carbon in Lake Melville, Labrador, Canada: Inferences from 210Pb, 137Cs, and δ13C

NASA Astrophysics Data System (ADS)

Kamula, C. M.

2016-12-01

Modern sedimentological processes, sources and distribution of sediment and organic carbon (OC) were investigated in recently deposited sediment from Lake Melville, Labrador, Canada to better understand the impacts of anthropogenic and climatic changes to the system over the last 100-150 years. Fifteen sediment cores collected across Lake Melville in 2013 and 2014 were analysed for 210Pb and 137Cs while stable isotope δ13Corg and percentage OC were measured down select cores and surface sediment. Mass accumulation rates (MARs) were established by fitting 210Pbex profiles to a two-layer advection diffusion model and validated with 137Cs. MARs varied between 0.04 and 0.41 g cm-2 yr-1 and decreased with distance from the Churchill River, the greatest source of sediment to the system. MARs were greatest in western Lake Melville immediately east of Goose Bay, reflecting the combined contributions of fine material carried eastward in the Churchill River plume and coarser particles from the Kenamu River. The sources of sediment were investigated by comparing inventories of 137Cs and excess 210Pb (210Pbex) to expected atmospheric inputs, which suggested sediment in Lake Melville is largely sourced from the watershed. In the eastern end of Lake Melville, an elevated 210Pbex inventory was associated with particle scavenging of dissolved 210Pb from inflowing marine water and is likely linked to increased primary production in the area. Surface sediment δ13Corg values (mean = -26.2 ± 1.75‰ SD) support a mixture of both terrestrial and marine organic carbon to the system. Using a transient tracer mixing model, the depth in each core corresponding to 90% sediment deposited pre and post hydroelectric development at Churchill Falls (1970) was established and applied to profiles of δ13Corg. This approach revealed an increase of terrestrial OC to Lake Melville post 1970 which we interpret to reflect change in climate and/or hydrology of the Churchill River.

Mercury Cycling in Sediments of the Northeast Pacific Continental Margin Between Southern California and Central Oregon, USA

NASA Astrophysics Data System (ADS)

Heim, W. A.; Coale, K. H.; Chiswell, H.; Olson, A.; Martenuk, S.; Bonnema, A.; Weiss-Penzias, P. S.

2017-12-01

Monomethylmercury (MMHg) production by anaerobic bacteria in sediments is considered to be a dominate source of MMHg to sediments and overlying surface water in the coastal environment. In this study, we measured total mercury (Hgt) and MMHg sediment and pore water concentrations and calculated diffusive sediment water exchange fluxes in samples collected on the coastal shelf in the California Current System. Sediment cores and overlying water were collected from 20 stations using a slow-entry multi-corer deployed during 4 oceanographic cruises over two years. The upper few centimeters of undisturbed cores were sectioned at the following depth increments: 0.5, 1, 1.5, 2, 3, 4, 5 cm. Pore waters were extracted via centrifugation and the Hgt and MMHg gradients were used to calculate fluxes into the overlying water column based upon molecular diffusion alone. Sediment concentrations for Hgt and MMHg ranged from 50 to 2338 pmoles g-1 and 0.1 to 9 pmoles g-1 respectively. Pore water and overlying water MMHg concentrations ranged from 0.1 to 2.2 pM and 0.03 to 0.3 pM respectively. Diffusional Hgt and MMHg sediment water fluxes ranged from 1.4 to 7.3 pmoles m-2 d-1 and -0.03 to 1.7 pmoles m-2 d-1 respectively. While the gradients in MMHg showed significant and widespread flux that would indicate an input into the waters of the shelf these fluxes were insufficient to sustain elevated concentrations at the sediment boundary layer, or at the depth of the shelf in general. Measurements made on the northwestern Atlantic shelf are in general an order of magnitude greater than those observed here. We suggest that the narrow eastern shelf of the California Current with little allochthonous inputs contrasts sharply with the broad shelf of the Eastern Seaboard with significant organic carbon, riverine and anthropogenic inputs. In general, the narrow shelf of the California Current seems to reflect the pelagic processes of the off shore regions for this element where water column production predominates the formation of the methylated forms.

Gas bubbles in marine mud-How small are they?

NASA Astrophysics Data System (ADS)

Reed, Allen H.; Briggs, Kevin B.

2003-10-01

Free gas in marine mud poses a challenging problem in the realm of ocean acoustics as it readily attenuates (i.e., scatters or absorbs) energy, such that objects lying below the gassy sediment are acoustically masked. Gas-laden sediments were located in 10- to 120-m water depth adjacent to the South Pass of the Mississippi River in East Bay using a 12-kHz transducer and the Acoustic Sediment Classification System. Several cores were collected in this region for physical property measurements. Some of the cores were x-rayed on medical and industrial computed tomography (CT) scanners. Volumetric CT images were used to locate gas bubbles, determine shapes and sizes to within the limits of the CT resolution. Free gas in the East Bay sediments was relegated to worm tubes as well as isolated pockets as was the case in Eckernförde Bay sediments [Abegg and Anderson, Mar. Geol. 137, 137-147 (1997)]. The primary significance of the present work is that gas bubbles have been determined to exist in the tens of μm size range, which is significantly smaller than the smallest bubbles that were previously resolved with medical CT (~440 μm) with NRL's HD-500 micro-CT System. [Work supported by ONR and NRL.

Acoustic backscatter of the 1995 flood deposit on the Eel shelf

USGS Publications Warehouse

Borgeld, J.C.; Hughes-Clarke, John E.; Goff, John A.; Mayer, Larry A.; Curtis, Jennifer A.

1999-01-01

Acoustic swath mapping and sediment box coring conducted on the continental shelf near the mouth of the Eel River revealed regional variations in acoustic backscatter that can be related to the shelf sedimentology. The acoustic-backscatter variations observed on the shelf were unusually narrow compared to the response of similar sediment types documented in other areas. However, the acoustic data revealed four principal bottom types on the shelf that can be related to sedimentologic differences observed in cores. The four areas are: (1) low acoustic backscatter associated with the nearshore-sand facies and the prodelta terraces of the Eel and Mad rivers, composed of fine sands and coarse silts with low porosity; (2) high acoustic backscatter associated with fine silts characterized by high porosity and deposited by the 1995 flood of the Eel River; (3) intermediate acoustic backscatter in the outer-shelf muds, where clayey silts are accumulating and the 1995 flood apparently had limited direct effect; and (4) intermediate acoustic backscatter near the fringes of the 1995 flood deposits and in areas where the flood sediments were more disrupted by post-depositional processes. The highest acoustic backscatter was identified in areas where the 1995 flood sediments remained relatively intact and near the shelf surface into the summer of 1995. Cores collected from these areas contained wavy or lenticular bedding. The rapid deposition of the high-porosity muddy layers results in better preservation of incorporated ripple forms than in areas less directly impacted by the flood deposit. The high-porosity muddy layers allow acoustic penetration into the sediments and result in greater acoustic backscatter from incorporated roughness elements.

Deposition, Alteration, and Resuspension of Colorado River Delta Sediments, Lake Powell, Utah

NASA Astrophysics Data System (ADS)

Kramer, N. M.; Parnell, R.

2002-12-01

Current drought conditions in the southwest United States have resulted in lowering water levels in Lake Powell, Utah. Delta sediments forming at the Colorado River inflow for the past 39 years are becoming exposed and reworked as lake levels continue to fall to over 22 meters below full pool level. Fine sediments act as a sink for pollutants by adsorbing contaminants to their surfaces. Reworking these sediments may pose a risk to water quality in the lake. We examine whether burial and time have sufficiently altered fine sediments in the delta and affected materials adsorbed on their surfaces. Fifteen lake cores and six sediment traps were collected from the sediment delta forming at the Colorado River inflow in Lake Powell. This research characterizes fine sediment mineralogy, the composition of exchangeable materials, and organic matter content within delta sediments to determine the type and amount of alteration of these sediments with cycles of burial and resuspension. We hypothesize that as sediments are reworked, organic carbon is degraded and organic nitrogen is released forming ammonium in these reducing conditions. Sediment trap samples will be used to test this hypothesis. Trap samples will be compared to subsamples from sediment cores to determine the amount of alteration of fine sediments. All samples are analyzed for organic carbon, organic nitrogen, ammonium, cation exchange capacity, exchangeable cation composition, and clay mineralogy. Organic carbon and nitrogen are analyzed using a Leco CN analyzer. Ammonium is analyzed using a Lachet ion chromatograph. Clay mineralogy is characterized using a Siemens D500 powder X-ray diffractometer. Cation exchange capacity and exchangeable cations are measured using standard soil chemical techniques. Clay mineral analyses indicate significant spatial and temporal differences in fine sediment entering the Lake Powell delta which complicates the use of a simple deposition/alteration/resuspension model using a single starting material.

Geochemical studies of backfill aggregates, lake sediment cores and the Hueco Bolson Aquifer

NASA Astrophysics Data System (ADS)

Thapalia, Anita

This dissertation comprises of three different researches that focuses on the application of geochemistry from aggregates, lake sediment cores and Hueco Bolson Aquifer. Each study is independent and presented in the publication format. The first chapter is already published and the second chapter is in revision phase. Overall, three studies measure the large scale (field) as well as bench scale (lab) water-rock interactions influenced by the climatic and anthropogenic factors spans from the field of environmental geology to civil engineering. The first chapter of this dissertation addresses the chemical evaluation of coarse aggregates from six different quarries in Texas. The goal of this work is to find out the best geochemical methods for assessing the corrosion potential of coarse aggregates prior to their use in mechanically stabilized earth walls. Electrochemical parameters help to define the corrosion potential of aggregates following two different leaching protocols. Testing the coarse and fine aggregates demonstrate the chemical difference due to size-related kinetic leaching effects. Field fines also show different chemistry than the bulk rock indicating the weathering impact on carbonate rocks. The second chapter investigates zinc (Zn) isotopic signatures from eight lake sediment cores collected both from pristine lakes and those impacted by urban anthropogenic contamination. Zinc from the natural weathering of rocks and anthropogenic atmospheric pollutants are transported to these lakes and the signatures are recorded in the sediments. Isotopic analysis of core samples provides the signature of anthropogenic contamination sources. Dated sediment core and isotopic analysis can identify Zn inputs that are correlated to the landuse and population change of the watersheds. Comparison of isotopic data from both pristine and urban lake sediment core also serves as an analog in other lake sediment cores in the world. The third chapter studies on Hueco Bolson Aquifer that an important sources of water in the El Paso/Cd. Juraez metroplex. To delineate the boundary between fresh and brackish water from the northern Hueco Bolson Aquifer, we utilize an integrative geochemical, geophysical, and sedimentological approach. The goal of this study is to use geophysical well-log analysis and the water chemical analysis for identifying the changes in the quality of the groundwater. A detailed microgravity survey is utilized to explore the subsurface geological structures that control the conduits and/or barriers of groundwater flow. A detailed geochemical analysis of aquifer samples provide salinity of groundwater that will complement to the subsurface structures obtained from the geophysical study. This fundamental research in developing methods from an integrated approach to estimate aquifer quality can be used as an analog for similar studies in other arid regions.

Mineralogy and Geochemistry from Trollveggen Vent Field Chimneys and Metalliferous Sediments (Mohns Ridge, West Jan Mayen Fracture Zone at 71°N)

NASA Astrophysics Data System (ADS)

Dias, S.; Cruz, I.; Fonseca, R.; Barriga, F. J.; Pedersen, R.

2010-12-01

The Jan Mayen vent fields were discovered in the Mohns Ridge during an expedition with the Norwegian research vessel "G.O. Sars" in July 2005. They comprise two main active areas: (1) Soria Moria and (2) Gallionella Garden & Trollveggen. The Trollveggen vent field is located at depths of 700-750 m. Venting takes place mainly through white smoker chimneys with fluid temperatures reaching up to 260-270°C. Here we present mineralogical and geochemical data from vent chimneys and metalliferous sediments collected at the Trollveggen vent field with an ROV. Cross-sections of chimneys present evident mineralogical zonation, showing acicular barite crystals in the outer parts and sulfide enrichments in the interior (Sph + Cpy +/- Py - Po). Sediments are mainly formed by vent fragments but also by minerals precipitated by diffuse fluid circulation, showing a mineral assemblage similar to that of chimneys. Microprobe analyses were obtained both in sulfates and sulphides revealing a particular sphalerite composition, characterized by low Fe (< 2%) and high total trace metal contents (up to 4%, including Cu, Ag and Au). Geochemical profiles of gravity cores collected in the area surrounding Jan Mayen were also performed in order to investigate the presence of additional hydrothermal activity in the area. Total geochemical analyses showed a slight enrichment in trace metals, such as Cu, Zn and Fe, with exception of one core that reached 85 ppm for Cu, 150 ppm for Zn and 20% for Fe. The metal enrichment in this core suggests hydrothermal activity in the neighboring area.

Geochemistry records from laminated sediments of Shira Lake (Russian Asia)

NASA Astrophysics Data System (ADS)

Phedorin, M.; Vologina, E.; Drebuschak, M.; Tolomeev, A.; Kirichenko, I.; Toyabin, A.

2009-04-01

We measured downcore elements distributions in five cores collected across the Shira Lake situated in Central part of Asia (E90o12', N54o30'). The lake is small (32km2), saline (ca.20g/l SO4-, Cl-, Na+, Mg+, K+), being filled with regional precipitation of about 300mm/year (mainly through one major tributary, river Son) and has no surface outflow. The aim of our study was to reconstruct history of changes in the regime of the lake that happened both before and during period of instrumental meteorological observations. In particular, we were interested in lake-level changes due to evaporation, water supply from surface and from underground sources, and in changes of bioproduction in the lake as well. To construct depth-age model for the cores, we measured Cs-137 and unsupported Pb-210 in top layers of the cores. The sedimentation rate thus identified varied in the range of 1-2 mm/year for different cores. We visually observed fine sedimentation ‘rhythms' having thickness of about 0.x-2.x mm: these layers may now be reliably identified as annual lamination. We also determined concentrations of elements in the sediments by recording x-ray fluorescence (XRF) spectra when continuously scanning the halves of the cores under sharp synchrotron radiation (SR) beam, using an instrument described in (Zolotarev et al., 2001). The resolution of the scanning was 0.1 mm. After processing of the measured XRF-SR data as in (Phedorin and Goldberg, 2005) we obtained downcore records of 20 elements. We correlated all five cores employing elements patterns. We qualitatively identified variations in surface-water supply treating markers of ‘clastic' material (Ti, Rb, Zr). We identified downcore variations in authgenic mineralization, which appeared to have different kinds: Ca-related, Sr-related, Ba-related, Fe-related. We tried to assess biogenic production changes from Br distribution, admitting analogy of Br in Shira sediments to Br in Lake Baikal sediments (Phedorin et al., 2000) and in Lake Khubsugul sediments (Phedorin et al., 2008). The cores we studied provide us with high-resolution geochemical records of last century for further meteorological correlations and regressions back to the past. We plan to reconstruct regional trends proceeding with the investigation of this kind and studying sediments of some other Khakas lakes. The investigation was supported by the grant from RFBR (09-05-98027) and grant from the Siberian Branch of Russian Academy of Science. Phedorin M.A., Goldberg E.L., Grachev M.A., Levina O.L., Khlystov O.M., Dolbnya I.P. The Comparison of Biogenic Silica, Br and Nd Distributions in the Sediments of Lake Baikal as Proxies of Changing Paleoclimates of the Last 480 ky. // Nuclear Instruments and Methods in Physics Research, 2000, V. A448, № 1-2, pp. 400-406. Phedorin M.A., Goldberg E.L. Prediction of absolute concentrations of elements from SR XRF scan measurements of natural wet sediments. Nuclear Instruments and Methods in Physics Research A 543 (2005), p. 274-279. Phedorin M.A., Fedotov A.P., Vorobieva S.S., Ziborova G.A.. Signature of long supercycles in the Pleistocene history of Asian limnic systems. J Paleolimnol, 2008, 40/1, pp. 445-452. Zolotarev K.V., Goldberg E.L., Kondratyev V.I., Kulipanov G.N., Miginsky E.G., Tsukanov V.M., Phedorin M.A., Kolmogorov Y.P. Scanning SR-XRF beamline for analysis of bottom sediments. // Nuclear Instruments and Methods in Physics Research, 2001, V. A470, N 1-2, pp. 376-379.

Limnological and climatic environments at Upper Klamath Lake, Oregon during the past 45 000 years

USGS Publications Warehouse

Bradbury, J.P.; Colman, Steven M.; Dean, W.E.

2004-01-01

Upper Klamath Lake, in south-central Oregon, contains long sediment records with well-preserved diatoms and lithological variations that reflect climate-induced limnological changes. These sediment archives complement and extend high resolution terrestrial records along a north-south transect that includes areas influenced by the Aleutian Low and Subtropical High, which control both marine and continental climates in the western United States. The longest and oldest core collected in this study came from the southwest margin of the lake at Caledonia Marsh, and was dated by radiocarbon and tephrochronology to an age of about 45 ka. Paleolimnological interpretations of this core, based upon geochemical and diatom analyses, have been augmented by data from a short core collected from open water environments at nearby Howards Bay and from a 9-m core extending to 15 ka raised from the center of the northwestern part of Upper Klamath Lake. Pre- and full-glacial intervals of the Caledonia Marsh core are characterized and dominated by lithic detrital material. Planktic diatom taxa characteristic of cold-water habitats (Aulacoseira subarctica and A. islandica) alternate with warm-water planktic diatoms (A. ambigua) between 45 and 23 ka, documenting climate changes at millennial scales during oxygen isotope stage (OIS) 3. The full-glacial interval contains mostly cold-water planktic, benthic, and reworked Pliocene lacustrine diatoms (from the surrounding Yonna Formation) that document shallow water conditions in a cold, windy environment. After 15 ka, diatom productivity increased. Organic carbon and biogenic silica became significant sediment components and diatoms that live in the lake today, indicative of warm, eutrophic water, became prominent. Lake levels fell during the mid-Holocene and marsh environments extended over the core site. This interval is characterized by high levels of organic carbon from emergent aquatic vegetation (Scirpus) and by the Mazama ash (7.55 ka), generated by the eruption that created nearby Crater Lake. For a brief time the ash increased the salinity of Upper Klamath Lake. High concentrations of molybdenum, arsenic, and vanadium indicate that Caledonia Marsh was anoxic from about 7 to 5 ka. After the mid-Holocene, shallow, but open-water environments returned to the core site. The sediments became dominated (>80%) by biogenic silica. The open-water cores show analogous but less extreme limnological and climatic changes more typical of mid-lake environments. Millennial-scale lake and climate changes during OIS 3 at Upper Klamath Lake contrast with a similar record of variation at Owens Lake, about 750 km south. When Upper Klamath Lake experienced cold-climate episodes during OIS 3, Owens Lake had warm but wet episodes; the reverse occurred during warmer intervals at Upper Klamath Lake. Such climatic alternations apparently reflect the variable position and strength of the Aleutian Low during the mid-Wisconsin.

Impacts of Ocean Acidification on Sediment Processes in Shallow Waters of the Arctic Ocean

PubMed Central

Gazeau, Frédéric; van Rijswijk, Pieter; Pozzato, Lara; Middelburg, Jack J.

2014-01-01

Despite the important roles of shallow-water sediments in global biogeochemical cycling, the effects of ocean acidification on sedimentary processes have received relatively little attention. As high-latitude cold waters can absorb more CO2 and usually have a lower buffering capacity than warmer waters, acidification rates in these areas are faster than those in sub-tropical regions. The present study investigates the effects of ocean acidification on sediment composition, processes and sediment-water fluxes in an Arctic coastal system. Undisturbed sediment cores, exempt of large dwelling organisms, were collected, incubated for a period of 14 days, and subject to a gradient of pCO2 covering the range of values projected for the end of the century. On five occasions during the experimental period, the sediment cores were isolated for flux measurements (oxygen, alkalinity, dissolved inorganic carbon, ammonium, nitrate, nitrite, phosphate and silicate). At the end of the experimental period, denitrification rates were measured and sediment samples were taken at several depth intervals for solid-phase analyses. Most of the parameters and processes (i.e. mineralization, denitrification) investigated showed no relationship with the overlying seawater pH, suggesting that ocean acidification will have limited impacts on the microbial activity and associated sediment-water fluxes on Arctic shelves, in the absence of active bio-irrigating organisms. Only following a pH decrease of 1 pH unit, not foreseen in the coming 300 years, significant enhancements of calcium carbonate dissolution and anammox rates were observed. Longer-term experiments on different sediment types are still required to confirm the limited impact of ocean acidification on shallow Arctic sediment processes as observed in this study. PMID:24718610

Impacts of ocean acidification on sediment processes in shallow waters of the Arctic Ocean.

PubMed

Gazeau, Frédéric; van Rijswijk, Pieter; Pozzato, Lara; Middelburg, Jack J

2014-01-01

Despite the important roles of shallow-water sediments in global biogeochemical cycling, the effects of ocean acidification on sedimentary processes have received relatively little attention. As high-latitude cold waters can absorb more CO2 and usually have a lower buffering capacity than warmer waters, acidification rates in these areas are faster than those in sub-tropical regions. The present study investigates the effects of ocean acidification on sediment composition, processes and sediment-water fluxes in an Arctic coastal system. Undisturbed sediment cores, exempt of large dwelling organisms, were collected, incubated for a period of 14 days, and subject to a gradient of pCO2 covering the range of values projected for the end of the century. On five occasions during the experimental period, the sediment cores were isolated for flux measurements (oxygen, alkalinity, dissolved inorganic carbon, ammonium, nitrate, nitrite, phosphate and silicate). At the end of the experimental period, denitrification rates were measured and sediment samples were taken at several depth intervals for solid-phase analyses. Most of the parameters and processes (i.e. mineralization, denitrification) investigated showed no relationship with the overlying seawater pH, suggesting that ocean acidification will have limited impacts on the microbial activity and associated sediment-water fluxes on Arctic shelves, in the absence of active bio-irrigating organisms. Only following a pH decrease of 1 pH unit, not foreseen in the coming 300 years, significant enhancements of calcium carbonate dissolution and anammox rates were observed. Longer-term experiments on different sediment types are still required to confirm the limited impact of ocean acidification on shallow Arctic sediment processes as observed in this study.

Unravelling the Paleoenvironmental and Diagenetic History of Fluviolacustrine Sediments from a Northern Kenya Rift Basin Through Analysis of HSPDP West Turkana-Kaitio Core Material

NASA Astrophysics Data System (ADS)

Rabideaux, N. M.; Chaudhary, M. S.; Deocampo, D.; Feibel, C. S.; Cohen, A. S.

2016-12-01

The Hominin Sites and Paleolakes Drilling Project (HSPDP) collected sediment cores from six rift basins in Ethiopia and Kenya. The goal of HSPDP is to construct high-resolution records of environmental change, and to understand how those changes relate to early human evolution and cultural adaptations. The West Turkana-Kaitio (WTK) site was targeted due to the abundant archeological and paleontological artifacts and fossils discovered around the basin. We conducted XRD and XRF analyses on HSPDP-WTK core material to construct a high-resolution record of paleoenvironmental conditions in the Kenya Rift during the Early Pleistocene ( 1.9-1.35 Ma). Mineralogical and geochemical trends were also used to identify the diagenetic history of fluviolacustrine sediments in the basin. The bulk mineralogy is comprised of mostly detrital feldspars, muscovite, α-quartz, and carbonates. Zeolites are present in intervals throughout the core, possibly suggesting pulses of increased salinity. Oxides and S-bearing minerals are abundant from 100-170 mbs, which may be indicative of redox and or hydrothermal processes in that interval. The lowermost portion of the core contains α- and β-quartz, pyrite and zeolites, suggesting either low-oxygen saline conditions or hydrothermal activity. Oriented clay analysis indicated multiple intervals of diagenesis, with the illitization of smectite related to hydrothermal and or microbial activity. Clay analysis provided evidence for a low degree of illitization in the upper portion of the core, whereas mixed-layered illite-smectite (I/S) contained 30-50% illite proximal to fault breccia and up to 70% illite below the faulted section, indicative of significant alteration in the lowermost portion of the core. Coupled mineralogical and geochemical analysis revealed a complex alteration history in the basin indicated by: 1) the presence of mixed-layer I/S throughout the 216 m core; 2) pronounced alteration proximal to faulting; and 3) authigenic silicates and pyrite in the basal section of the core.

Reconstruction of organochlorine compound inputs in the Tagus Prodelta.

PubMed

Mil-Homens, Mário; Vicente, Maria; Grimalt, Joan O; Micaelo, Cristina; Abrantes, Fátima

2016-01-01

Twenty century time-resolved variability of riverine deposits of polychlorobiphenyls (PCBs), DDTs, hexachlorocyclohexanes (HCHs) and hexachlorobenzene (HCB) was studied in three (210)Pb dated sediment cores collected in a depositional shelf area adjacent to the Tagus estuary (the Tagus Prodelta). The geographic and temporal distribution patterns were consistent with discharge of these organochlorine compounds (OCs) in the area associated with the Tagus mouth. Their concentrations were not correlated with the sedimentary total organic carbon. The PCB down-core profiles were dominated by CB138 and CB153 (hexa-CBs) congeners followed by CB180 (hepta-CBs). Principal Component Analysis of the congener distributions of these compounds did not define temporal down-core trends. The ratios of DDT metabolites (p,p'-DDE/p,p'-DDT) were consistent with recent DDT inputs into the environment and/or earlier applications and long-term residence in soils/sediments until these were eroded and remobilized. Copyright © 2015 Elsevier B.V. All rights reserved.

Estimating growth rates of uncultivated clades of archaea and bacteria in marine sediments

NASA Astrophysics Data System (ADS)

Lloyd, K. G.

2016-12-01

The vast majority of microbes present in marine sediments have never been cultivated in laboratory conditions. It is therefore difficult to estimate the growth rates of these organisms in situ. Quantitative PCR (qPCR) and 16S rRNA gene libraries from sediments below 10 cm show very little change in abundance of these organisms with depth or with redox conditions. Therefore, we hypothesized that uncultivated clades of bacteria and archaea that are ubiquitous in marine sediments, actually grow in the upper 10 cm of marine sediments. We collected sediment cores from the White Oak River estuary, sectioned them in 1 cm intervals, and examined the changes in abundance of uncultivated microbes with depth using 16S rRNA gene libraries and qPCR. We found that some of the key clades associated with the deep subsurface microbiome, such as Bathyarchaeota and MBG-D, increase in abundance with depth, demonstrating extremely slow growth in these shallow subsurface sediments.

Sediment erosion and transport at the Rio Grande mouth : report for the National Border Technology Program and International Boundary and Water Commission.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chapin, D. Michael, Jr.; Langford, Richard; Neu, Roene

2003-11-01

The mouth of the Rio Grande has become silted up, obstructing its flow into the Gulf of Mexico. This is problematic in that it has created extensive flooding. The purpose of this study was to determine the erosion and transport potential of the sediments obstructing the flow of the Rio Grande by employing a unique Mobile High Shear Stress flume developed by Sandia's Carlsbad Programs Group for the US Army Corps of Engineers. The flume measures in-situ sediment erosion properties at shear stresses ranging from normal flow to flood conditions for a variable depth sediment core. The flume is inmore » a self-contained trailer that can be placed on site in the field. Erosion rates and sediment grain size distributions were determined from sediment samples collected in and around the obstruction and were subsequently used to characterize the erosion potential of the sediments under investigation.« less

Glacimarine Sedimentary Processes and Deposits at Fjord-Terminating Tidewater Glacier Margins

NASA Astrophysics Data System (ADS)

Streuff, K.; O'Cofaigh, C.; Lloyd, J. M.; Noormets, R.; Nielsen, T.; Kuijpers, A.

2016-12-01

Many fjords along Arctic coasts are influenced by tidewater glaciers, some of them fast-flowing ice sheet outlets. Such glaciers provide important links between terrestrial and marine environments, and, due to their susceptibility to climatic and oceanographic changes, have undergone a complex history of advance and retreat since the last glacial maximum (LGM). Although a growing body of evidence has led to a better understanding of the deglacial dynamics of individual glaciers since the LGM, their overall Holocene glacimarine processes and associated sedimentary and geomorphological products often remain poorly understood. This study addresses this through a detailed analysis of sediment cores, swath bathymetric and sub-bottom profiler data collected from seven fjords in Spitsbergen and west Greenland. The sediment cores preserve a complex set of lithofacies, which include laminated and massive muds in ice-proximal, and bioturbated mud in more ice-distal settings, diamicton in iceberg-dominated areas and massive sand occurring as lenses, laminae and thick beds. These facies record the interplay of three main glacimarine processes, suspension settling, iceberg rafting and sediment gravity flows, and collectively emphasise the dominance of glacial meltwater delivery to sedimentation in high Arctic fjords. The seafloor geomorphology in the fjords shows a range of landforms that include glacial lineations associated with fast ice-flow, terminal moraines and debris lobes marking former maximum glacier extents, and small transverse moraines formed during deglaciation by glaciotectonic deformation at the grounding line and crevasse-squeezing. Additional landforms such as iceberg ploughmarks, submarine channels, pockmarks, and debris lobes formed during or after deglaciation by iceberg calving, erosion by meltwater, and sediment reworking. We present here a new model for sedimentary and geomorphological processes in front of contemporary tidewater glaciers, which integrates our findings with those from Alaska, Canada, and east Greenland.

A simple and inexpensive technique for assessing microbial contamination during drilling operations

NASA Astrophysics Data System (ADS)

Friese, André; Vuillemin, Aurèle; Kallmeyer, Jens; Wagner, Dirk

2016-04-01

Exploration of the Deep Biosphere relies on drilling, which inevitably causes infiltration of drilling fluids, containing allochthonous microbes from the surface, into the core. Therefore it is absolutely necessary to trace contamination of the sediment core in order to identify uncontaminated samples for microbiological investigations. Several techniques have been used in the past, including fluorescent dyes, perfluorocarbon tracers and fluorescent microspheres. Fluorescent dyes are inexpensive and easy to analyze on-site but are sensitive to light, pH and water chemistry. Furthermore, significant sorption to clays can decrease the fluorescence signal. Perfluorocarbon tracers are chemically inert hydrophobic compounds that can be detected with high sensitivity via gas chromatography, which might be a problem for on-site analysis. Samples have to be taken immediately after core retrieval as otherwise the volatile tracer will have diffused out of the core. Microsphere tracers are small (0.2 - 0.5 μm diameter) fluorescent plastic particles that are mixed into the drilling fluid. For analysis, these particles can be extracted from the sediment sample, transferred onto a filter and quantified via fluorescence microscopy. However, they are very expensive and therefore unsuitable for deep drilling operations that need large amounts of drilling fluids. Here, we present an inexpensive contamination control approach using fluorescent pigments initially used for coloring plastics. The price of this tracer is nearly three orders of magnitude lower than conventional microsphere tracers. Its suitability for large drilling campaigns was tested at the ICDP Deep Drilling at Lake Towuti, Sulawesi, Indonesia. The tracer was diluted 1:1000 in lake water, which was used as the drilling fluid. Additionally, a plastic bag filled with 20 mL of undiluted tracer was attached to the core catcher to increase the amount of particles in the liner fluid right at the core. After core retrieval, the core was cut and the liner fluid collected. From each whole round core (WRC) that was taken for microbiological and biogeochemical analyses, small samples of 1 cc were retrieved with sterile cutoff syringes from the rim, the center and an intermediate position. After dilution and homogenization in 9 mL MilliQ water, 10 μL of the sediment slurry was transferred onto a filter membrane and particles counted via fluorescence microscopy. Additionally, particles in the liner fluid were also quantified. This allows the quantification of the amount of drilling fluid that has entered the sediment sample during drilling. The minimum detectable volume of drilling fluid was in the order of single nanoliters per cc of sediment, which is in the range of established techniques. The presented method requires only a minimum of equipment and allows rapid determination of contamination in the sediment core and an easy to handle on-site analysis at low costs. The sensitivity is in the same range as perfluorocarbon and microsphere tracer applications. Thus, it offers an inexpensive but powerful technique for contamination assessment for future drilling campaigns.

Reconnaissance for trace metals in bed sediment, Wright Patman Lake, near Texarkana, Texas

USGS Publications Warehouse

McKee, Paul W.

2001-01-01

Many contaminants can be introduced into the environment by urban and industrial activities. The drainage area of Wright Patman Lake is influenced by these activities. Among the contaminants associated with urban and industrial activities are trace metals such as arsenic, lead, mercury, and zinc. These contaminants are relatively insoluble in water and commonly are found in stream, lake, and reservoir bottom sediment, especially the clays and silts within the sediment.Wright Patman Lake serves as the major potable water supply for the city of Texarkana and surrounding communities. Texarkana, located in the northeastern corner of Texas and the southwestern corner of Arkansas, had a population of about 56,000 in 1998, which reflects an increase of about 3.4 percent from the 1990 census (Ramos, 1999). Texarkana Water Utilities, which manages the water-treatment facilities for Texarkana, proposes to dredge the lake bed near the water intake in the Elliot Creek arm of Wright Patman Lake. It is possible that arsenic, lead, mercury, and other trace metals might be released into the water if the bed sediment is disturbed. Bed sediment in the Elliot Creek arm of the lake, in particular, could contain trace metals because of its proximity to Red River Army Depot and because industrial land use is prevalent in the headwaters of Elliot Creek.The U.S. Geological Survey (USGS), in cooperation with Reconnaissance for Trace Metals in Bed Sediment, Wright Patman Lake, Near Texarkana, Texas In cooperation with the Texarkana Water Utilities conducted a reconnaissance of Wright Patman Lake to collect bed-sediment samples for analysis of trace metals. This report presents trace metal concentrations in bed-sediment samples collected at six sites along the Elliot Creek arm of the lake, one site each in two adjacent arms, and one site near the dam on June 16, 1999 (fig. 1). One bed-sediment sample was collected at each of the nine sites, and one sediment core was collected at each of two of the sites. Trace metal concentrations are compared to sediment-quality guidelines for the protection of aquatic life and to screening levels based on historical trace metal concentrations in bed sediment of Texas reservoirs.

Factors influencing the biogeochemistry of sedimentary carbon and phosphorus in the Sacramento-San Joaquin Delta

USGS Publications Warehouse

Nilsen, E.B.; Delaney, M.L.

2005-01-01

This study characterizes organic carbon (Corganic) and phosphorus (P) geochemistry in surface sediments of the Sacramento-San Joaquin Delta, California. Sediment cores were collected from five sites on a sample transect from the edge of the San Francisco Bay eastward to the freshwater Consumnes River. The top 8 cm of each core were analyzed (in 1-cm intervals) for Corganic, four P fractions, and redox-sensitive trace metals (uranium and manganese). Sedimentary Corganic concentrations and Corganic:P ratios decreased, while reactive P concentrations increased moving inland in the Delta. The fraction of total P represented by organic P increased inland, while that of authigenic P was higher bayward than inland reflecting increased diagenetic alteration of organic matter toward the bayward end of the transect. The redox indicator metals are consistent with decreasing sedimentary suboxia inland. The distribution of P fractions and C:P ratios reflect the presence of relatively labile organic matter in upstream surface sediments. Sediment C and P geochemistry is influenced by site-specific particulate organic matter sources, the sorptive power of the sedimentary material present, physical forcing, and early diagenetic transformations presumably driven by Corganic oxidation. ?? 2005 Estuarine Research Federation.

Adjustable shear stress erosion and transport flume

DOEpatents

Roberts, Jesse D.; Jepsen, Richard A.

2002-01-01

A method and apparatus for measuring the total erosion rate and downstream transport of suspended and bedload sediments using an adjustable shear stress erosion and transport (ASSET) flume with a variable-depth sediment core sample. Water is forced past a variable-depth sediment core sample in a closed channel, eroding sediments, and introducing suspended and bedload sediments into the flow stream. The core sample is continuously pushed into the flow stream, while keeping the surface level with the bottom of the channel. Eroded bedload sediments are transported downstream and then gravitationally separated from the flow stream into one or more quiescent traps. The captured bedload sediments (particles and aggregates) are weighed and compared to the total mass of sediment eroded, and also to the concentration of sediments suspended in the flow stream.

Historic brownfields and industrial activity in Kingston, Ontario: assessing potential contributions to mercury contamination in sediment of the Cataraqui River.

PubMed

Manion, N C; Campbell, L; Rutter, A

2010-04-01

The waterfront of historic Kingston, Ontario (pop: 113,000) has been used for industrial activities for over a century. More than 40 industries have existed within the inner harbour, and while many of these industries are no longer present, the properties that they operated on remain as potential sources of persistent contamination to the present day, including mercury. To assess the extent and distribution of total mercury (THg) contamination, 21 sediment cores as well as pore water samples were collected within the inner harbour of Kingston. The spatial distribution of THg in the surface sediment is not homogenous; with concentrations in the surface sediment along the southwestern shoreline, adjacent to the former industrial properties, are significantly greater (p<0.01) than the rest of the inner harbour, and were above the Federal severe effect limit (>2000 microg/kg;) guideline for sediment. MeHg was detected in some sediment cores, and was found to have a significant, positive correlation with [THg] in the surface sediment (0-5 cm). THg was not found in storm sewer discharges, but was detected in terrestrial soil near the Kingston Rowing Club at a concentration of more than 4000 microg/kg. Significant [THg] was detected in runoff draining from contaminated shoreline soils, indicating that erosion from terrestrial sources may be an ongoing source of Hg to the sediment. It can be concluded that there is an increased risk over time to surrounding ecosystems where properties with historical contamination are not remediated until they are developed. (c) 2010 Elsevier B.V. All rights reserved.

An examination of historic inorganic sedimentation and organic matter accumulation in several marsh types within the Mobile Bay and and Mobile-Tensaw River Delta region

USGS Publications Warehouse

Smith, Christopher G.; Osterman, Lisa E.; Poore, Richard Z.

2013-01-01

Mass accumulation rates (MAR; g cm-2 y-1), linear sedimentation rates (LSR; cm y-1), and core geochronology derived from excess lead-210 (210Pb) profiles and inventories measured in six sediment cores collected from marsh sites from the MobileTensaw River Delta and Mobile Bay region record the importance of both continuous and event-driven inorganic sedimentation over the last 120 years. MAR in freshwater marshes varied considerably between sites and through time (0.24 and 1.31 g cm-2 y-1). The highest MARs occurred in the 1950s and 1960s and correspond to record discharge events along the Mobile and Tensaw Rivers. In comparison, MAR at salt marsh sites increased almost threefold over the last 120 years (0.05 to 0.18 g cm-2 y-1 or 0.23 to 0.48 cm y-1). From 1880 to 1960, organic accumulation remained fairly constant (20%), while intermittent pulses of high inorganic sedimentation were observed following 1960. The pulses in inorganic sedimentation coincide with several major hurricanes (e.g., Hurricanes Camille, Fredric, Georges, and Ivan). The nearly threefold increase in MAR in salt marshes during the last 120 years would thus appear to be partially dependent on inorganic sedimentation from storm events. This study shows that while hurricanes, floods, and other natural hazards are well-known threats to human infrastructure and coastal ecosystems, these events also transport sediment to marshes that help abate other pressures such as sea-level rise (SLR) and subsidence.

Sedimentological and radiochemical characteristics of marsh deposits from Assateague Island and the adjacent vicinity, Maryland and Virginia, following Hurricane Sandy

USGS Publications Warehouse

Smith, Christopher G.; Marot, Marci E.; Ellis, Alisha M.; Wheaton, Cathryn J.; Bernier, Julie C.; Adams, C. Scott

2015-09-15

This report serves as an archive for sedimentological and radiochemical data derived from the surface sediments and marsh cores collected March 26–April 4, 2014. Select surficial data are available for the additional sampling periods October 21–30, 2014. Downloadable data are available as Excel spreadsheets and as JPEG files. Additional files include: Field documentation, x-radiographs, photographs, detailed results of sediment grain size analyses, and formal Federal Geographic Data Committee metadata (data downloads).

Dendrochemical assessment of mercury releases from a pond and dredged-sediment landfill impacted by a chlor-alkali plant.

PubMed

Maillard, François; Girardclos, Olivier; Assad, Mohamad; Zappelini, Cyril; Pérez Mena, Julia Maria; Yung, Loïc; Guyeux, Christophe; Chrétien, Stéphane; Bigham, Gary; Cosio, Claudia; Chalot, Michel

2016-07-01

Although current Hg emissions from industrial activities may be accurately monitored, evidence of past releases to the atmosphere must rely on one or more environmental proxies. We used Hg concentrations in tree cores collected from poplars and willows to investigate the historical changes of Hg emissions from a dredged sediment landfill and compared them to a nearby control location. Our results demonstrated the potential value of using dendrochemistry to record historical Hg emissions from past industrial activities. Copyright © 2016 Elsevier Inc. All rights reserved.

Current status and historical variations of DDT-related contaminants in the sediments of Lake Chaohu in China and their influencing factors.

PubMed

Kang, Lei; He, Qi-Shuang; He, Wei; Kong, Xiang-Zhen; Liu, Wen-Xiu; Wu, Wen-Jing; Li, Yi-Long; Lan, Xin-Yu; Xu, Fu-Liu

2016-12-01

The temporal-spatial distributions of DDT-related contaminants (DDXs), including DDT (dichlorodiphenyltrichloroethane), DDE (dichlorodiphenyldichloroethylene) and DDD (dichlorodiphenyldichloroethane), in the sediments of Lake Chaohu and their influencing factors were studied. p,p-DDE and p,p-DDD were found to be the two dominant components of DDXs in both surface and core sediments. The parent DDT compounds were still detectable in sediment cores after the late 1930s. Historical usage of technical DDT was identified as the primary source of DDXs in sediments, as indicated by DDT/(DDD + DDE) ratios of less than one. The residual levels of DDXs were higher in the surface and core sediments in the western lake area than in other lake areas, which might be due to the combined inflow effects of municipal sewage, industrial wastewater and agricultural runoff. The DDX residues in the sediment cores reached peak values in the late 1970s or early 1980s. There were significant positive relationships between DDX residues in sediment cores with annual DDT production and with fine particulate sizes (<4.5 μm). The relationship between the DDXs and TOC in sediment was complex, as indicated by the significant differences among the surface and core sediments. The algae-derived organic matter significantly influenced the amount of residue, composition and distribution of DDXs in the sediments. The DDD/DDE ratios responded well to the anaerobic conditions in the sediments that were caused by algal blooms after the late 1970s in the western lake area. This suggests that the algae-derived organic matter was an important factor and served as a biomarker of eutrophication and also affected the DDX residues and lifecycle in the lake ecosystem. Copyright © 2016 Elsevier Ltd. All rights reserved.

Recent paleoseismicity record in Prince William Sound, Alaska, USA

NASA Astrophysics Data System (ADS)

Kuehl, Steven A.; Miller, Eric J.; Marshall, Nicole R.; Dellapenna, Timothy M.

2017-12-01

Sedimentological and geochemical investigation of sediment cores collected in the deep (>400 m) central basin of Prince William Sound, along with geochemical fingerprinting of sediment source areas, are used to identify earthquake-generated sediment gravity flows. Prince William Sound receives sediment from two distinct sources: from offshore (primarily Copper River) through Hinchinbrook Inlet, and from sources within the Sound (primarily Columbia Glacier). These sources are found to have diagnostic elemental ratios indicative of provenance; Copper River Basin sediments were significantly higher in Sr/Pb and Cu/Pb, whereas Prince William Sound sediments were significantly higher in K/Ca and Rb/Sr. Within the past century, sediment gravity flows deposited within the deep central channel of Prince William Sound have robust geochemical (provenance) signatures that can be correlated with known moderate to large earthquakes in the region. Given the thick Holocene sequence in the Sound ( 200 m) and correspondingly high sedimentation rates (>1 cm year-1), this relationship suggests that sediments within the central basin of Prince William Sound may contain an extraordinary high-resolution record of paleoseismicity in the region.

Enantiomer fractions of chlordane components in sediment from U.S. Geological Survey sites in lakes and rivers

USGS Publications Warehouse

Ulrich, E.M.; Foreman, W.T.; Van Metre, P.C.; Wilson, J.T.; Rounds, S.A.

2009-01-01

Spatial, temporal, and sediment-type trends in enantiomer signatures were evaluated for cis- and trans-chlordane (CC, TC) in archived core, suspended, and surficial-sediment samples from six lake, reservoir, and river sites across the United States. The enantiomer fractions (EFs) measured in these samples are in good agreement with those reported for sediment, soil, and air samples in previous studies. The chlordane EFs were generally close to the racemic value of 0.5, with CC values ranging from 0.493 to 0.527 (usually >0.5) and TC values from 0.463 to 0.53 (usually <0.5). EF changes with core depth were detected for TC and CC in some cores, with the most non-racemic values near the top of the core. Surficial and suspended sediments generally have EF values similar to the top core layers but are often more non-racemic, indicating that enantioselective degradation is occurring before soils are eroded and deposited into bottom sediments. We hypothesize that rapid losses (desorption or degradation) from suspended sediments of the more bioavailable chlordane fraction during transport and initial deposition could explain the apparent shift to more racemic EF values in surficial and top core sediments. Near racemic CC and TC in the core profiles suggest minimal alteration of chlordane from biotic degradation, unless it is via non-enantioselective processes. EF values for the heptachlor degradate, heptachlor epoxide (HEPX), determined in surficial sediments from one location only were always non-racemic (EF ??? 0.66), were indicative of substantial biotic processing, and followed reported EF trends.

Examination of core samples from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope: Effects of retrieval and preservation

USGS Publications Warehouse

Kneafsey, T.J.; Lu, H.; Winters, W.; Boswell, R.; Hunter, R.; Collett, T.S.

2011-01-01

Collecting and preserving undamaged core samples containing gas hydrates from depth is difficult because of the pressure and temperature changes encountered upon retrieval. Hydrate-bearing core samples were collected at the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well in February 2007. Coring was performed while using a custom oil-based drilling mud, and the cores were retrieved by a wireline. The samples were characterized and subsampled at the surface under ambient winter arctic conditions. Samples thought to be hydrate bearing were preserved either by immersion in liquid nitrogen (LN), or by storage under methane pressure at ambient arctic conditions, and later depressurized and immersed in LN. Eleven core samples from hydrate-bearing zones were scanned using x-ray computed tomography to examine core structure and homogeneity. Features observed include radial fractures, spalling-type fractures, and reduced density near the periphery. These features were induced during sample collection, handling, and preservation. Isotopic analysis of the methane from hydrate in an initially LN-preserved core and a pressure-preserved core indicate that secondary hydrate formation occurred throughout the pressurized core, whereas none occurred in the LN-preserved core, however no hydrate was found near the periphery of the LN-preserved core. To replicate some aspects of the preservation methods, natural and laboratory-made saturated porous media samples were frozen in a variety of ways, with radial fractures observed in some LN-frozen sands, and needle-like ice crystals forming in slowly frozen clay-rich sediments. Suggestions for hydrate-bearing core preservation are presented.

Vertical and lateral flux on the continental slope off Pakistan: correlation of sediment core and trap results

NASA Astrophysics Data System (ADS)

Schulz, H.; von Rad, U.

2014-06-01

Due to the lack of bioturbation, the varve-laminated muds from the oxygen minimum zone (OMZ) off Pakistan provide a unique opportunity to precisely determine the vertical and lateral sediment fluxes in the nearshore part of the northeastern Arabian Sea. West of Karachi (Hab area), the results of two sediment trap stations (EPT and WPT) were correlated with 16 short sediment cores on a depth transect crossing the OMZ. The top of a distinct, either reddish- or light-gray silt layer, 210Pb-dated as AD 1905 ± 10, was used as an isochronous stratigraphic marker bed to calculate sediment accumulation rates. In one core, the red and gray layer were separated by a few (5-10) thin laminae. According to our varve model, this contributes < 10 years to the dating uncertainty, assuming that the different layers are almost synchronous. We directly compared the accumulation rates with the flux rates from the sediment traps that collected the settling material within the water column above. All traps on the steep Makran continental slope show exceptionally high, pulsed winter fluxes of up to 5000 mg m-2 d-1. Based on core results, the flux at the seafloor amounts to 4000 mg m-2 d-1 and agrees remarkably well with the bulk winter flux of material, as well as with the flux of the individual bulk components of organic carbon, calcium carbonate and opal. However, due to the extreme mass of remobilized matter, the high winter flux events exceeded the capacity of the shallow traps. Based on our comparisons, we argue that high-flux events must occur regularly during winter within the upper OMZ off Pakistan to explain the high accumulations rates. These show distribution patterns that are a negative function of water depth and distance from the shelf. Some of the sediment fractions show marked shifts in accumulation rates near the lower boundary of the OMZ. For instance, the flux of benthic foraminifera is lowered but stable below ~1200-1300 m. However, flux and sedimentation in the upper eastern Makran area are dominated by the large amount of laterally advected fine-grained material and by the pulsed nature of the resuspension events at the upper margin during winter.

Palaeoenvironmental reconstructions on the Mozambique coast as a tool to understand human evolution: from modern analogues to borehole interpretation

NASA Astrophysics Data System (ADS)

Gomes, Ana; Skosey-LaLonde, Elena; Zinsious, Brandon; Gonçalves, Célia; Bicho, Nuno; Raja, Mussa; Cascalheira, João; Haws, Jonathan

2017-04-01

In the framework of the project "Stone Age Vilankulos: Modern Human Origins Research South of the Rio Save, Mozambique" a geoarchaeological survey was conducted in 2016 aiming to better understand the environmental history and landscape evolution of the study area including the environmental context of human occupation. During the survey, 23 sediment surface samples were collected across a variety of environments, namely: freshwater environment - Elephant River basin in Southwestern Mozambique - and brackish and marine tidal environments - Inhambane coastal area, Southeastern Mozambique. These samples will be used as modern analogues to interpret the sedimentological and paleontological record of 4 cores collected in a mangrove area of the Inhambane estuary and then reconstruct its palaeoenvironmental evolution. All the sampling points were georeferenced and the study area was overflown with a drone to collect photogrammetric data. Both surface and core samples were used for diatom, texture and geochemical analysis. Diatoms will be used as the main palaeontological proxy, because they are unicellular algae with a short-live cycle and largely sensible to environmental variables such as salinity, sediment texture and duration of the tidal inundation. Preliminary data on the modern diatoms analysis showed that diatom diversity is high and the equitability is low in all environments. Cores sedimentological description and dating are also presented. The work was supported by the project PTDC/EPHARQ/4168/2014, funded by the Portuguese Foundation for Science and Technology.

Manifestation of the geomagnetic Mono Lake excursion in sediments of the northern part of the Barents Sea

NASA Astrophysics Data System (ADS)

Goos'kova, E.; Volkova, Y.; Piskarev, A.; Morner, N.-A.; Abrahamsen, N.; Dergachev, V.; Raspopov, O.

2003-04-01

Palaeomagnetic characteristics of cores from three boreholes (AK-56, AK-87, AK-98) collected in the northern part of the Barents sea (79-80 N) during the expedition of the Research Vessel "Academician Karpinsky" in 1998 have been studied. The cores were taken from depths of 329, 377, and 473 m, respectively. In all three cores, changes in inclination from -80 to -150 degrees were observed at a depth of 110-130 cm (in 6-8 core samples), which suggests that this phenomenon can be attributed to a geomagnetic field excursion. Basing on dating of the lithologic Holocene-Pleistocene boundary, the sedimentation rate in this part of the Barents Sea can be estimated to be 5-7 cm/1000 years. In this case the age of the excursion is about 24 000 BP, i.e., it corresponds to the Mono Lake excursion. In the Barents Sea sediments, the manifestation of this excursion was revealed for the first time in the ACB-2 core taken in the central part of the sea. At a depth of 150-180 cm, all three cores (in 8-10 samples) were found to have a layer with abnormally high natural remanent magnetization (up to 6-11 nT with a mean value of 1.5 nT) and magnetic susceptibility (up to 1.0-1.7 x 10-3 SI with a mean value of 0.4 x 10-3 SI). Basing on lithological data, the time of formation of this layer can be estimated as approximately 30 000 - 35 000 BP. A reference layer at the depth corresponding to the Holocene-Pleistocene boundary with similar changes in magnetic susceptibility attributed to climate change was found in the cores taken from the central part of the Barents sea earlier. It is likely that sharp changes in magnetic properties of sediments in the northern part of the Barents Sea about 30 000 - 35 000 BP are also attributable to a sharp climate change (warming) during that period of time. This work was supported by INTAS, Grant 97-31008 and PFBR, Grant 00-05-64921.

Distribution characteristics and sources of trace metals in sediment cores from a trans-boundary watercourse: An example from the Shima River, Pearl River Delta.

PubMed

Gao, Lei; Wang, Zhuowei; Shan, Jiju; Chen, Jianyao; Tang, Changyuan; Yi, Ming; Zhao, Xinfeng

2016-12-01

Metal pollution in sediments from the Shima River, a typical transboundary watercourse in the Pearl River Delta area, was investigated. Sediment cores were collected at eight sites from the upper to the lower reaches crossing Shenzhen, Dongguan and Huizhou cities. Sediment physicochemical properties and the total concentrations of trace metals (V, Cr, Co, Ni, Cu, Zn, As, Cd and Pb) were determined. The results showed that riverine sediment was significantly polluted by Cr (content range: 13.8-469mgkg -1 ), Ni (14.1-257mgkg -1 ), Cu (10.8-630mgkg -1 ), Zn (50.2-1700mgkg -1 ) and Cd (0.172-2.26mgkg -1 ). The geoaccumulation indices (I geo ) of trace metals decreased in the order Cd>Zn>Ni>Cu>Co>Cr>Pb>As>V. The pollution load indices and potential ecological risk indices (RI) at the sampling sites were similar, with more severe pollution and greater risk presenting in the upper and middle reaches (S1-S6) compared with the lower reaches (S7 and S8). Cd contributed significantly (77.2-87.6%) to the RI. Source identification based on multivariate statistical techniques, including principal component analysis (PCA), correlation analysis (CA) and hierarchical cluster analysis (HACA), was performed to differentiate the origins of trace metals. PCA and CA yielded similar results, indicating that As and V originated from natural sources (e.g., parent materials) and that the other metals were related to anthropogenic activities. HACA based on the I geo showed that Cd was associated mainly with fertilizers, and the origins of Cr, Ni, Cu and Zn were probably industrial effluents, whereas Co and Pb were related to traffic activities. HACA of sediment cores suggested that Dongguan and Shenzhen cities contribute large quantities of metals to the riverine sediment, whereas few metals were discharged from Huizhou City. Copyright © 2016 Elsevier Inc. All rights reserved.

Temperature sensitivity of methanogenesis in a thermokarst lake sediment core

NASA Astrophysics Data System (ADS)

Heslop, J. K.; Walter Anthony, K. M.; Grosse, G.; Anthony, P.; Bondurant, A.

2016-12-01

Little is known about temperature sensitivity of permafrost organic carbon (OC) mineralization over time scales of years to centuries following thaw. Due to their formation and thaw histories, taliks (thaw bulbs) beneath thermokarst lakes provide a unique natural laboratory from which to examine how permafrost thawed in saturated anaerobic conditions responds to changes in temperature following long periods of time since thaw. We anaerobically incubated samples from a 590 cm thermokarst lake sediment core near Fairbanks, Alaska at four temperatures (0, 3, 10, and 25 ºC) bracketing observed talik temperatures. We show that since initial thaw 400 yr BP CH4 production shifts from being most sensitive to at lower (0-3 ºC; Q10-EC=1.15E7) temperatures to being most sensitive at higher (10-25 ºC; Q10-EC=67) temperatures. Frozen sediments collected from beneath the talik, thawed at the commencement of the incubation, had significant (p ≤ 0.05) increases in CH4 production rates at lower temperatures but did not show significant CH4 production rate increases at higher temperatures (10-25 ºC). We hypothesize the thawing of sediments removed a major barrier to C mineralization, leading to rapid initial permafrost C mineralization and preferential mineralization of the most biolabile OC compounds. In contrast, sediments which had been thawed beneath the lake for longer periods of time did not experience statistically significant increases in CH4 production at lower temperatures (0-10 ºC), but had high temperature sensitivities at higher temperatures (10-25 ºC). We believe these rate increases are due to warmer temperatures in the experimental incubations crossing activation energy thresholds, allowing previously recalcitrant fractions of OC to be utilized, and/or the presence of different microbial communities adapted to thawed sediments. Recently-deposited sediments at shallow depths in the lake core experienced increases in CH4 production across all incubation temperatures (Q10-ST=4.4).

Evaluation of dredged material proposed for ocean disposal from Shark River Project area

DOE Office of Scientific and Technical Information (OSTI.GOV)

Antrim, L.D.; Gardiner, W.W.; Barrows, E.S.

1996-09-01

The objective of the Shark River Project was to evaluate proposed dredged material to determine its suitability for unconfined ocean disposal at the Mud Dump Site. Tests and analyses were conducted on the Shark River sediments. The evaluation of proposed dredged material consisted of bulk sediment chemical and physical analysis, chemical analyses of dredging site water and elutriate, water-column and benthic acute toxicity tests, and bioaccumulation tests. Individual sediment core samples collected from the Shark River were analyzed for grain size, moisture content, and total organic carbon (TOC). One sediment composite was analyzed for bulk density, specific gravity, metals, chlorinatedmore » pesticides, polychlorinated biphenyl (PCB) congeners, polynuclear aromatic hydrocarbons (PAHs), and 1,4- dichlorobenzene. Dredging site water and elutriate, prepared from suspended-particulate phase (SPP) of the Shark River sediment composite, were analyzed for metals, pesticides, and PCBs. Benthic acute toxicity tests and bioaccumulation tests were performed.« less

Triclosan and Hydroxylated Polybrominated Diphenyl Ethers in Lake and Esturaine Sediments

NASA Astrophysics Data System (ADS)

Arnold, W. A.; Kerrigan, J. F.; McNeill, K.; Erickson, P. R.; Grandbois, M.

2014-12-01

Halogenated diphenyl ethers are a class of emerging contaminants that includes the antibacterial compound triclosan and the flame retardant polybrominated diphenyl ethers (PBDEs). Both triclosan and hydroxylated polybrominated diphenyl ethers (OH-BDEs) are known to form dioxins when exposed to sunlight in aqueous solution. Thus, it is important to understand the sources and presence of these compounds in the environment, especially because OH-BDEs are breakdown products of PBDEs and also naturally produced compounds. In this work, the levels of OH-BDEs were determined in lake sediments from Minnesota and esturaine sediments from San Francisco Bay. Both surface sediments over a broad spatial area and sediment cores were collected and analyzed. Triclosan was used as a marker of wastewater as a source of the targeted emerging contaminants. The relationship between triclosan and OH-BDE levels provides insight into the importance of natural and anthropogenic influences on the levels of OH-BDEs.

Arctic Sediment Transport from Land to Sea - An Integrated Study of Coastal - Marine Processes and Deposits in Dicksonfjorden, Svalbard

NASA Astrophysics Data System (ADS)

Jensen, M.; Choi, K.; Forwick, M.; Howe, J. A.; Husum, K.; Korsun, S.; Maat, D.; Nam, S. I.

2016-12-01

Valleys and fjords are the key transport and storage systems for sediments and biogeochemical elements from high arctic landscapes to the ocean. Sediment and nutrient fluxes are important for the biochemical cycle in the fjords and eventually in the ocean, and are important input data to earth system models. At present, high latitude systems are underrepresented in such models (Russell, 2014). Dicksonfjorden is a fjord in the larger Isfjorden system, Central Spitsbergen, Svalbard. It has no direct glacial input, in contrast to fjords affected by tidewater glaciers. The sediment supply is very high and the inner fjord receives sediment from a tide-influenced delta. This study is part of a multidisciplinary project aiming at mapping and quantifying sediment types and dispersal patterns in present Arctic valley - fjord systems and is the first comprehensive study of the depositional system in Dicksonfjorden. The first field campaign took place in summer 2016, when detailed mapping of the tidal delta and the sea floor in the inner fjord, coring onshore and offshore and sampling for foraminifera, nutrients and microbial abundances were performed. The surface mapping is based on high-resolution drone images, which will be processed to a high-resolution digital elevation model, and the bathymetry and sediment distribution data from the sea floor has been collected with a Gavia Offshore Surveyor AUV, providing high-resolution bathymetry and backscatter data of the seabed. Core transects from the delta surface will be described and compared to marine cores from the fjord basin retrieved from R/V Helmer Hanssen. Sediment accumulation rates will be assessed from 210Pb and 137Cs radionuclides. Preliminary results on the physical and chemical characteristics of the sedimentation system in inner Dicksonfjorden will be presented and implications for the fjord ecosystem will be discussed. References Russell , J.L., 2014. Control on the Latitudinal distribution of climate processes: Results from Earth System Model simulations. AAPG/SEPM Hedberg Research Conference "Latitudinal controls on stratigraphic models and sedimentary concepts, Banff, Alberta, Canada, September 28 - October 1, 2014, Abstract volume, 10-11.

The aquatic macrophyte seed bank in Lake Onalaska, Wisconsin

USGS Publications Warehouse

McFarland, D.G.; Rogers, S.J.

1998-01-01

Submersed aquatic vegetation, dominated by Vallisneria americana Michx., declined dramatically in Lake Onalaska (Navigation Pool 7, on the Upper Mississippi River) following drought conditions in the late 1980s. Coinciding with the decline were marked increases in the abundance of Myriophyllum spicatum L., particularly in areas vacated by V. americana. Recent evidence indicates that much of the lake has remained unvegetated, but that since 1994, beds of V. americana have made a partial recovery. While the production of vegetative propagules may largely account for increases in populations of both species, the extent to which seed production may contribute to their expansion in the lake is unknown. To assess the germination potential and distribution of the aquatic macrophyte seed bank in Lake Onalaska, sediment cores (5 cm deep) were collected from 74 sampling sites injury 1996. Seedling emergence from sediments was observed in an environmental growth chamber operated at 25 C and a 14-hr photoperiod over a period of eight weeks. Fifteen species of aquatic macrophytes germinated in sediments from 55 sites. V. americana seedlings emerged from sediments from 36 sites throughout the lake, but were most prevalent in sediments collected within or downstream (within 250 m) of established V. americana beds. Seedlings of M. spicatum emerged from only two collected sediments that had supported this species in protected areas. These findings suggest that seed production may play a greater role in the dispersal of V. americana than M. spicatum, and further emphasize basic differences in their survival strategies, particularly in flowing water systems.

Effects of urbanization and long-term rainfall on the occurrence of organic compounds and trace elements in reservoir sediment cores, streambed sediment, and fish tissue from the Santa Ana River basin, California, 1998

USGS Publications Warehouse

Burton, Carmen A.

2002-01-01

Organcochlorine compounds, semivolatile-organic compounds (SVOC), and trace elements were analyzed in reservoir sediment cores, streambed sediment, and fish tissue in the Santa Ana River Basin as part of the U.S. Geological Survey's National Water-Quality Assessment Program. Three reservoirs were sampled in areas that have different degrees of urbanization. Streambed sediment and fish tissue collected at 12 sites were divided into two groups, urban and nonurban. More organochlorine compounds were detected in reservoir sediment cores, streambed sediment and fish tissue, and at higher concentrations at urban sites than at nonurban sites. At all sites, except West Street Basin, concentrations of organochlorine compounds were lower than the probable-effect concentration (PEC). At the highly urbanized West Street Basin, chlordane and p,p'-DDE exceeded the PEC throughout the historical record. The less stringent threshold-effect concentration (TEC) was exceeded for six compounds at eight sites. Most of the organochlorine compounds detected in streambed sediment and fish tissue were at urban sites on the Santa Ana River as opposed to its tributaries, suggesting accumulation and persistence in the river. More SVOCs were detected in reservoir sediment cores and streambed sediment, and at higher concentrations, at urban sites than at nonurban sites. At all the sites, except West Street Basin, concentrations of SVOCs were lower than the PEC. At West Street Basin, chrysene, pyrene, and total polycyclic-aromatic hydrocarbons exceeded the PEC throughout the historical record. The TEC was exceeded for 10 compounds at 3 sites. Most of the SVOCs were detected in streambed sediment at urban sites on tributaries to the Santa Ana River rather than the mainstem itself. The less frequent occurrence and lower concentrations in the Santa Ana River suggest that SVOCs are less persistent than organochlorine compounds, possibly as a result of volatization, gradation, or dilution. Most trace-element detections in reservoir sediment cores and streambed sediment were at urban sites, and the concentrations were generally higher than at nonurban sites. Lead and zinc exceeded their PECs at West Street Basin throughout the historical record; copper exceeded its PEC at Canyon Lake, an area of urban growth. The TEC was exceeded for 10 compounds at 11 sites. Frequency of detection and concentration did not differ between tributary and Santa Ana River sites, which may be attributed to the fact that trace elements occur naturally. Four trace elements (arsenic, copper, mercury, and selenium) had higher concentrations in fish tissue at nonurban sites than at urban sites. Concentrations decreased over time for organochlorine compounds at all three reservoirs, probably a result of the discontinued use of many of the compounds. Decreasing trends in SVOCs and trace elements were observed at West Street Basin, but increasing trends were observed at Canyon Lake. Concentrations of organochlorine compounds, SVOCs, and trace elements were higher during periods of above average rainfall at both West Street Basin and Canyon Lake.

THE DISTRIBUTION OF 137CESIUM AND OTHER TRACE CONSTITUENTS IN GREEN BAY, LAKE MICHIGAN

EPA Science Inventory

137Cs, Cadmium, and PCBs were measured in a series of sediment cores collected in Green Bay between 1987 and 1989. Analysis of the spatial distribution of the chemicals can be shown to be dependent on the nature of the input - totally from the atmosphere, totally riverine, and a ...

Benthic foraminifera records in marine sediments during the Holocene from Pescadero basin, Gulf of California, Mexico

NASA Astrophysics Data System (ADS)

Valdez, M.; Perez-Cruz, L. L.; Roy, P.; Monreal, M.; Fenero, R.

2013-05-01

Gravity core T-56 (256 cm length) was collected in Pescadero Basin located on the western side of the Gulf of California within the oxygen minim zone (OMZ) at 597 cm depth, aboard of the R/V "El Puma". Pescadero basin is located at mouth of the gulf; because of its location is sensitive to record the changes in the gulf and in the Eastern Pacific Ocean. The sedimentary sequence is analyzed to contribute to the understanding the oceanographic variability in the southern part of the gulf of California during the Holocene using benthic foraminifera assemblages and organic carbon as proxies of organic matter flux and bottom water oxygenation. In general, the core is characterized by silty-clay sediments, and it exhibits a turbidite between 198 and 134 cm, distinguished by sandy sediments and reworking material. From 134 cm to the top shows a visible laminated structure. The initial chronology is based on three AMS radiocarbon dates, and estimated sedimentation rates are 0.22 and 0.19 mm/yr for the first 32 cm of the core. Six radiocarbon dates are in progress. Preliminary results of benthic foraminiferal assemblages showed that species of Bolivina are dominated, mainly megalospheric forms, from 134 cm to top of the core. They are small and thin-shelled forms (e.g., Bolivina subadvena, Bolivina minuta, Bolivina seminuda, Bolivina plicata), and also Buliminella, Cassidulina and Epistominella are abundant. In particular, species of Bolivina are environmental indicators and exhibit a typical reproductive dimorphism. The predominance of the genus Bolivina suggest organic flux variations, because of the productivity changes that might be related to changes in ocean circulation and in the environmental variability in the region.

Deposition of selenium and other constituents in reservoir bottom sediment of the Solomon River Basin, north-central Kansas

USGS Publications Warehouse

Christensen, Victoria G.

1999-01-01

The Solomon River drains approximately 6,840 square miles of mainly agricultural land in north-central Kansas. The Bureau of Reclamation, U.S. Department of the Interior, has begun a Resource Management Assessment (RMA) of the Solomon River Basin to provide the necessary data for National Environmental Policy Act (NEPA) compliance before renewal of long-term water-service contracts with irrigation districts in the basin. In May 1998, the U.S. Geological Survey (USGS) collected bottom-sediment cores from Kirwin and Webster Reservoirs, which are not affected by Bureau irrigation, and Waconda Lake, which receives water from both Bureau and non-Bureau irrigated lands. The cores were analyzed for selected physical properties, total recoverable metals, nutrients, cesium-137, and total organic carbon. Spearman's rho correlations and Kendall's tau trend tests were done for sediment concentrations in cores from each reservoir. Selenium, arsenic, and strontium were the only constituents that showed an increasing trend in concentrations for core samples from more than one reservoir. Concentrations and trends for these three constituents were compared to information on historical irrigation to determine any causal effect. Increases in selenium, arsenic, and strontium concentrations can not be completely explained by Bureau irrigation. However, mean selenium, arsenic, and strontium concentrations in sediment from all three reservoirs may be related to total irrigated acres (Bureau and non-Bureau irrigation) in the basin. Selenium, arsenic, and strontium loads were calculated for Webster Reservoir to determine if annual loads deposited in the reservoir were increasing along with constituent concentrations. Background selenium, arsenic, and strontium loads in Webster Reservoir are significantly larger than post-background loads.

Core descriptions, core photographs, physical property logs and surface textural data of sediment cores recovered from the continental shelf of the Monterey Bay National Marine Sanctuary during the research cruises M-1-95-MB, P-2-95-MB, and P-1-97-MB

USGS Publications Warehouse

Orzech, Kevin M.; Dahl, Wendy E.; Edwards, Brian D.

2001-01-01

In response to the 1992 creation of the Monterey Bay National Marine Sanctuary (MBNMS), the United States Geological Survey (USGS) initiated a multiyear investigation of the Sanctuary continental margin. As part of the investigative effort, this report summarizes the shipboard procedures, subsequent laboratory analyses, and data results from three seafloor sampling cruises conducted on the continental shelf between Monterey peninsula, CA and San Francisco, CA. The cruises were conducted in 1995 aboard the NOAA Ship McArthur (M-1-95-MB) and in 1995 and 1997 aboard the R/V Point Sur (P-2-95-MB and P-1-97-MB). Scientists and representatives from the Environmental Protection Agency (EPA), the National Oceanic and Atmospheric Administration (NOAA), the California Department of Fish and Game (CDFG), the University of California Santa Cruz (UCSC), and the San Jose State University Moss Landing Marine Laboratory (SJSU-MLML) supported the research effort. In this report we present sediment descriptions, sediment textural data, physical property logs, station metadata, and photographs of subcores from a total of three hundred and eighty four sample stations. At these sites either a box corer, MultiCore™r, grab sampler or a combination of these sampling devices were used to collect the sea floor sediments. The report is presented in an interactive web-based format with each mapped core station linked to the corresponding description and photo, and to a spreadsheet of surface texture and other sampling data.

Potential geologic hazards and constraints for blocks in proposed North Atlantic OCS Oil and gas lease sale 52

USGS Publications Warehouse

Carpenter, G.B.; Cardinell, A.P.; Francois, D.K.; Good, L.K.; Lewis, R.L.; Stiles, N.T.

1982-01-01

Analysis of high-resolution geophysical data collected over 540 blocks tentatively selected for leasing in proposed OCS Oil and Gas Lease Sale 52 (Georges Bank) revealed a number of potential geologic hazards to oil and gas exploration and development activities: evidence of mass movements and shallow gas deposits on the continental slope. No potential hazards were observed on the continental shelf or rise. Other geology-related problems, termed constraints because they pose a relatively low degree of risk and can be routinely dealt with by the use of existing technology have been observed on the continental shelf. Constraints identified in the proposed sale area are erosion, sand waves, filled channels and deep faults. Piston cores were collected for geotechnical analysis at selected locations on the continental slope in the proposed lease sale area. The core locations were selected to provide information on slope stability and to establish the general geotechnical properties of the sediments. Preliminary results of a testing program suggest that the surficial sediment cover is stable with respect to mass movement.

Distribution of clay minerals on the Alaskan margin near Barrow Canyon revealed by Diffuse Spectral Reflectance measurements

NASA Astrophysics Data System (ADS)

Orsburn, C.; Ortiz, J. D.; Polyak, L.; Grebmeier, J. M.; Darby, D.

2007-12-01

Sediment clay mineral assemblages provide an excellent means of assessing the provenance of Arctic sediment due to the variety of sediment transport mechanisms at work and the existence of distinct weathering sources from differing bedrock geology. During HOTRAX Leg 1 aboard the USCG Ice breaker Healy (cruise HLY0501), we collected jumbo piston cores on the Alaskan margin near Barrow Canyon which provide detailed Holocene sedimentary records. Measurements of Diffuse Spectral Reflectance (DSR) were collected at 1cm resolution from the split surface of the cores using a Minolta CM-2600d UV/VIS spectrophotometer (400-700nm wavelength range; 10nm resolution; 3mm spot size). To interpret the resulting downcore records, we present a preliminary study using 28 coretop sediment samples collected by the Shelf-Basin Interaction program in 2004 arrayed in four transects across the shelf near Barrow Canyon. The samples were analyzed using an ASD Labspec Pro FR UV/VIS/NIR spectrometer (250-2500nm wavelength range, 2-10nm resolution; 20mm spot size). Our results indicate that the measurements from the two instruments are offset by constant factors, but can be easily compared. To estimate the clay mineralogy of the cores, we decomposed the matrix of DSR measurements from the coretop and downcore samples using principle component analysis and compared the resulting factor score patterns with mineral diffuse spectral reflectance signatures from known samples measured in our lab or available from version 5 of the USGS Digital Spectral Library. The three leading modes extracted by principle component analysis of the downcore samples are applicable to the coretops. We infer that the first principle component mode relates to smectite, the second to chlorite, and the third to a mixture of illite and goethite (herein referred to as illite - goethite). The geographic and bathymetric trends in the coretop data indicate that (1) the smectite and illite - goethite components both increase with depth and reach greater values in the two western transects than in the two eastern transects closest to the coast and Barrow Canyon, (2) the smectite and illite- goethite components are anticorrelated in the two western transects, but not in the two eastern transects, (3) chlorite decreases with depth and is highest in the two transects closest to Barrow Canyon. These results suggest that the chlorite on the Alaskan margin is transported by nearshore currents from the Bering Straight and then by bottom currents flowing through the Barrow Canyon. Accordingly, we interpret downcore chlorite peaks inferred from DSR measurements in our sediment cores as evidence of times of enhanced input of Pacific water to the Alaskan Margin.

Sediment Relative Paleointensity Record With Slow-sedimentation Rates: Implication For a Chronological Tool In The Slow-sedimentation Sequence

NASA Astrophysics Data System (ADS)

Kanamatsu, T.

2006-12-01

Usefulness of paleointensity records with high-sedimentation rates in stratigraphic correlation have been proved (e.g. Stoner et al., 1998, Laj et al., 2000, Stoner et al., 2000), because the sediment geomagnetic paleointensity data makes possible the fine time correlation between cores on the older sediment than the range of AMS 14C. As father application of the sediment paleointensity for chronological tool, we examined the paleointensity record of much slower sedimentation rate. The paleointensity record of the slower sedimentation sequence is supposed to show the convoluted record by the filtering effect of the post- depositional remanent magnetization, then a unique and different pattern depending on the sedimentation rate (e.g. Guyodo and Channell, 2002). We studied the record of the cores obtained from the West Philippine Sea Basin (Water depth ca. 5000 to 6000 m). The analyses of paleomagnetic direction proved that the cores contain Jaramillo and Olduvai Events. The sedimentation rates of cores estimated from magnetostratigraphy are less than 1cm/kyr (0.6-0.4 cm/kyr). Proxy of paleointensity (NRM20mT/ARM20mT) applied to cores reveals the variations in the records are dominate in c.a. 100 ky cycle. Comparing to other published paleointensity record, it is clear that the record includes ca.100-ky cycle in spite of slower sedimentation rates, although other high frequency records were not identified. It is suggests that geomagnetic events of a few to several kys are recordable in the sediment. The paleointensity in the slow-sedimentation record is still useful for the age control utilizing the lower frequency signal, especially for investigating of less age information sequence such as the deep sea sediment below CCD, but not for fine correlation by high frequency data.

Late-Quaternary changes of biogenic fluxes in the pacific sector of the Southern Ocean

NASA Astrophysics Data System (ADS)

Giglio, F.; Langone, L.; Capotondi, L.; Morigi, C.; Focaccia, P.; Frignani, M.; Ravaioli, M.

2003-04-01

During the last decade the research project BIOSESO of the Italian National Research Program for Antarctica (PNRA) has collected 13 gravity cores and 3 box-cores along a N-S transect at about 175^oE in the Southern Ocean. In this presentation we discuss the results from 6 sediment cores sampled between 62^oS and 71^oS. This area embraces the Polar Front and the Marginal Ice Zone. The data set includes the contents of organic carbon, biogenic silica, CaCO_3 and some metals (Ba, Al, Fe, Mn) involved in the biogeochemical cycles. Chronologies were based on 230Thex profiles and the boundaries of the isotope stages were set assuming that biological productivity was enhanced during periods of less ice cover. Then , 230Thex, organic carbon, biogenic silica and biogenic Ba distributions were compared to the glacial-interglacial stage boundaries and corresponding ages of the δ18O record of Martinson et al. (1987). At the sampling sites sediment accumulation rates range between 0.2 to 3.8 cm ka-1. The higher values characterize the interglacial stages and the southern stations. Processes of sediment redistribution at sea bottom were enlightened by a comparison of measured and expected fluxes of 230Thex . The Polar Front zone is characterized by winnowing, whereas sediments along the continental slope of the Ross Sea are mainly subject to focussing processes. The environmental factors that drive changes of biogenic particle fluxes during glacial-interglacial transitions have been investigated.

A chronicle of the changes undergone by a maritime territory, the Bay of Toulon (Var Coast, France), and their consequences on PCB contamination.

PubMed

Wafo, Emmanuel; Abou, Lydia; Nicolay, Alain; Boissery, Pierre; Perez, Thierry; Ngono Abondo, Rose; Garnier, Cédric; Chacha, Mama; Portugal, Henri

2016-01-01

This study evaluated the distribution of polychlorinated biphenyls (PCBs) in 39 surface sediment samples and four cores collected in Toulon Bay, a semiclosed area submitted to various anthropogenic inputs. The concentration of PCBs in the superficial sediment samples ranged from 1.7 to 2530 ng g(-1) dry weight. The spatial distribution of these compounds suggested that the high concentrations of these contaminants are located in the small bay and are related to human activities. In the larger bay, the concentrations were in the same order of magnitude than those reported in others locations around the world. Comparison of the levels with target values from the French legislation shows that, except for four polluted sites with critical values (N2: values ≥1 mg kg(-1) dry weight) in the smaller bay, PCBs levels throughout the larger and the smaller bay are lower than the accepted values (N1: values <0.5 mg kg(-1) dry weight). The PCBs in the sediment cores ranged from 0.8 to 739 ng g(-1) dry weight dependent core. Vertical profiles indicated earlier usage of PCBs which coincided with the history of the Toulon Bay. In this study, using alkane, we could follow the PCBs pollution history over about 80 years and estimate a sedimentation rate of about 0.32 cm year in the small Bay of Toulon.

Continuous transport of Pacific-derived anthropogenic radionuclides towards the Indian Ocean

PubMed Central

Pittauer, Daniela; Tims, Stephen G.; Froehlich, Michaela B.; Fifield, L. Keith; Wallner, Anton; McNeil, Steven D.; Fischer, Helmut W.

2017-01-01

Unusually high concentrations of americium and plutonium have been observed in a sediment core collected from the eastern Lombok Basin between Sumba and Sumbawa Islands in the Indonesian Archipelago. Gamma spectrometry and accelerator mass spectrometry data together with radiometric dating of the core provide a high-resolution record of ongoing deposition of anthropogenic radionuclides. A plutonium signature characteristic of the Pacific Proving Grounds (PPG) dominates in the first two decades after the start of the high yield atmospheric tests in 1950’s. Approximately 40–70% of plutonium at this site in the post 1970 period originates from the PPG. This sediment record of transuranic isotopes deposition over the last 55 years provides evidence for the continuous long-distance transport of particle-reactive radionuclides from the Pacific Ocean towards the Indian Ocean. PMID:28304374

Summary of water- and sediment-quality data for Anacostia River well sites sampled in July-August 2002

USGS Publications Warehouse

Miller, Cherie V.; Klohe, Cheryl A.

2003-01-01

This data report is a summary of chemical analyses conducted by the U.S. Geological Survey on ground water and sediment in the tidal Anacostia River watershed, Washington, D.C. during July-August 2002. Cores were drilled and wells were established at three shoreline sites: two wells at the New York Avenue overpass, two wells at the Kenilworth Aquatic Gardens, and one well at Anacostia Park. Additionally, two cores were collected by hoverprobe in mudflats on the river: one by Benning Road and one in the mouth of Beaverdam Creek. Chemical analyses included volatile organic compounds, semi-volatile organic compounds or polyaromatic hydrocarbons, organochlorine pesticides, aroclors and total polychlorinated biphenyls, metals, nutrients, biochemical and chemical oxygen demands, total phenols, total cyanide, oil and grease, and total suspended and dissolved solids in aqueous phases.

Diversity of Microbial Communities and Quantitative Chemodiversity in Layers of Marine Sediment Cores from a Causeway (Kaichu-Doro) in Okinawa Island, Japan.

PubMed

Soliman, Taha; Reimer, James D; Yang, Sung-Yin; Villar-Briones, Alejandro; Roy, Michael C; Jenke-Kodama, Holger

2017-01-01

Microbial community diversity and chemodiversity were investigated in marine sediments adjacent to the Okinawan "Kaichu-Doro" Causeway, which was constructed 46 years ago to connect a group of four islands (Henza-jima, Miyagi-jima, Ikei-jima, Hamahiga-jima) to the Okinawan main island. This causeway was not built on pilings, but by land reclamation; hence, it now acts as a long, thin peninsula. The construction of this causeway was previously shown to have influenced the surrounding marine ecosystem, causing ecosystem fragmentation and loss of water circulation. In this study, we collected sediment cores ( n = 10) from five paired sites in 1 m water depths. Each pair of sites consisted of one site each on the immediate north and south sides of the causeway. Originally the members of each pair were much closer to each other (<150 m) than to other pairs, but now the members of each pair are isolated by the causeway. Each core was 60-80 cm long and was divided into 15-cm layers. We examined the vertical diversity of microbial communities and chemical compounds to determine the correlation between chemodiversity and microbial communities among marine sediment cores and layers. Principal coordinate analyses (PCoA) of detected compounds and of bacterial and archaeal operational taxonomic units (OTUs) revealed that the north and south sides of the causeway are relatively isolated, with each side having unique microbial OTUs. Additionally, some bacterial families (e.g., Acidaminobacteraceae, Rhizobiaceae, and Xanthomonadaceae) were found only on the south side of Kaichu-Doro. Interestingly, we found that the relative abundance of OTUs for some microbial families increased from top to bottom, but this was reversed in some other families. We conclude that the causeway has altered microbial community composition and metabolite profiles in marine sediments.

A Multiproxy Approach to Unraveling Climate and Human Demography in the Peruvian Altiplano from a 5000 year Lake Sediment Core

NASA Astrophysics Data System (ADS)

Vaught-Mijares, R. M.; Hillman, A. L.; Abbott, M. B.; Werne, J. P.; Arkush, E.

2017-12-01

Drought and flood events are thought to have shaped the ways in which Andean societies have adapted to life in the Titicaca Basin region, particularly with regard to land use practices and settlement patterns. This study examines a small lake in the region, Laguna Orurillo. Water isotopes suggest that the lake primarily loses water through evaporation, making it hydrologically sensitive. In 2015, a 3.4 m overlapping sediment record was collected and inspected for evidence of shallow water facies and erosional unconformities to reconstruct paleohydrology. Sediment core chronology was established using 7 AMS radiocarbon dates and 210Pb dating and indicates that the core spans 5000 years. Additional sediment core measurements include magnetic susceptibility, bulk density, organic/carbonate content, and XRD. Results show a pronounced change in sediment composition from brittle, angular salt deposits to massive calcareous silt and clay around 5000 years BP. Multiple transitions from clay to sand show potential lake level depressions at 1540, 2090, and 2230, yr BP that are supported by a drastic increase in carbonate composition from 2760-1600 yr BP. Additional shallow-water periods may be reflected in the presence of rip-up clasts from 4000 to 3000 yr BP. These early interpretations align well with existing hydrologic records from Lake Titicaca. In order to develop a more detailed climate and land use record, isotope analyses of authigenic carbonate minerals using δ13C and δ18O and leaf waxes using δD are being developed. Ultimately, this record will be linked with records from nearby Lagunas Arapa and Umayo. Additional proxies for human population such as fecal 5β-stanols and proximal anthropologic surveys will be synthesized to contribute to a regional understanding of Holocene climate variability and human demography in the Peruvian Altiplano.

Sediment property changes in response to the glacial activity on the continental slope to the eastern side of Pennell-Iselin Bank in the Ross Sea, Antarctica

NASA Astrophysics Data System (ADS)

Ha, Sangbeom; Khim, Boo-Keun; Colizza, Ester; Marci, Patrizia; Sagnotti, Leonardo; Caricchi, Chiara; Langone, Leonardo; Giglio, Federico; Kuhn, Gerhard

2017-04-01

High latitude marine environments including the Antarctic continental margin have sensitively responded to the climate change, and the Ross Sea is one of these examples. Subglacial marine sedimentary changes have been studied extensively in the continental shelf areas of the Ross Sea to understand the growth and retreat of glaciers in response to the glacial-interglacial changes. However, the continental slope areas of the Ross Sea have not been investigated comparatively less. Thus, in order to comprehend the glaciomarine sedimentation change on the continental slope of the Ross Sea, 3 gravity cores (GC1, GC2, GC3) and 3 box cores (BC1, BC2, BC3) were collected from 3 sites (RS14-C1, C2, C3 by decreasing water depth), respectively, across the continental slope to the eastern side of the Pennell-Iselin Bank during XXIX PNRA (Rosslope II) cruise in 2014. A variety of sedimentological (grain size, magnetic susceptibility, XRF) and geochemical (biogenic opal, total organic carbon, CaCO3, δ13C of organic matter) properties were analyzed along with AMS 14C dating of bulk sediments. All core sediments consist of mostly hemipelagic sandy clay or silty clay with scattered IRD (Ice-Rafted Debris). Sediment color of three cores changes consistently downward from brown to gray with some alternations in core GC1. Based on the basic sediment properties such as sediment color, grain size, and magnetic susceptibility, sediment lithology was decided to divide Unit A and Unit B, both of which were further divided into two subunits. Despite old carbon effect, AMS 14C dates confirm that Unit A belongs to the Holocene and Unit B covers the deglacial to last glacial period at the top of cores. Unit A is characterized by low TOC, low CaCO3, low biogenic opal content and low C/N ratios, whereas Unit B is characterized by high TOC, high CaCO3, moderate to high biogenic opal content and high C/N ratios. Consequently, Unit A represents the modern and interglacial sediments deposited mainly by the suspension settling of biogenic particles in the open marine condition. In contrast, because Unit B shows higher TOC, CaCO3 content and C/N ratios, these sediments might be supplied by the lateral melt-water plume or distal part of debris flow originated from the front of grounding ice in the subglacial continental shelf under the ice shelf and during the glacial or post-glacial period. Thus, Unit B contains mostly reworked and eroded continental shelf sediments and IRDs. In addition, because the peaks of biogenic opal and TOC contents at Site C1 are distinctly higher than Sites C2 and C3, surface water production occurred under seasonally open marine condition at the deeper Site C1. In conclusion, the influence of subglacial continental shelf sedimentation in terms of melt-water transport and/or distal stage of debris flow was limited as far as to Site C2 during the deglacial and glacial period. However, such depositional effect was insignificant, but the seasonal open marine condition was recognized, at the deeper Site C1 in the continental slope of the Ross Sea.

Contaminated Sediment Core Profiling

EPA Science Inventory

Evaluating the environmental risk of sites containing contaminated sediments often poses major challenges due in part to the absence of detailed information available for a given location. Sediment core profiling is often utilized during preliminary environmental investigations ...

Historical contributions of phosphorus from natural and agricultural sources and implications for stream water quality, Cheney Reservoir watershed, south-central Kansas

USGS Publications Warehouse

Pope, Larry M.; Milligan, Chad R.; Mau, David Phillip

2002-01-01

An examination of soil cores collected from 43 nonagricultural coring sites in the Cheney Reservoir watershed of south-central Kansas was conducted by the U.S. Geological Survey in September 1999. The cores were collected as part of an ongoing cooperative study with the city of Wichita, Kansas. The 43 sites (mostly cemeteries) were thought to have total phosphorus concentrations in the soil that are representative of natural conditions (unaffected by human activity). The purpose of this report is to present the analysis and evaluation of these soil cores, to quantify the phosphorus contributions to Cheney Reservoir from natural and agricultural sources, and to provide estimates of stream-water-quality response to natural concentrations of total phosphorus in the soil. Analysis of soil cores from the 43 sites produced natural concentrations of total phosphorus that ranged from 74 to 539 milligrams per kilogram with a median concentration of 245 milligrams per kilogram in 2-inch soil cores and from 50 to 409 milligrams per kilogram with a median concentration of 166 milligrams per kilogram in 8-inch soil cores. Natural concentrations of total phosphorus in soil were statistically larger in samples from coring sites in the eastern half of the watershed than in samples from coring sites in the western half of the watershed. This result partly explains a previously determined west-to-east increase in total phosphorus yields in streams of the Cheney Reservoir watershed. A comparison of total phosphorus concentrations in soil under natural conditions to the historical mean total phosphorus concentration in agriculturally enriched bottom sediment in Cheney Reservoir indicated that agricultural activities within the watershed have increased total phosphorus concentrations in watershed soil that is transported in streams to about 2.9 times natural concentrations. Retention efficiencies for phosphorus and sediment historically transported to Cheney Reservoir were calculated at 92 and 99 percent, respectively. Most of the phosphorus was retained in bottom sediment. Sediment accumulation in Cheney Reservoir was less than reservoir design-life specifications on the basis of the age of the reservoir. Estimates of mean total phosphorus concentrations for selected streams in the Cheney Reservoir watershed under natural concentrations of total phosphorus in soil and a historic set of watershed conditions indicate that water from two of the five streamflow sampling sites would not meet the total phosphorus water-quality goal of 0.10 milligram per liter established by the Cheney Reservoir Watershed Task Force Committee. These results imply that the water-quality goal for total phosphorus in some streams of the watershed may not be met simply by reducing the amount of phosphorus applied. Instead, meeting the goal could involve a combination of approaches-for example, reducing the agricultural distribution of phosphorus and implementing changes in watershed activities to mitigate phosphorus movement to surface water.

Provenance and depositional history of continental slope sediments in the Southwestern Gulf of Mexico unraveled by geochemical analysis

NASA Astrophysics Data System (ADS)

Armstrong-Altrin, John S.; Machain-Castillo, María Luisa; Rosales-Hoz, Leticia; Carranza-Edwards, Arturo; Sanchez-Cabeza, Joan-Albert; Ruíz-Fernández, Ana Carolina

2015-03-01

The aim of this work is to constrain the provenance and depositional history of continental slope sediments in the Southwestern Gulf of Mexico (~1089-1785 m water depth). To achieve this, 10 piston sediment cores (~5-5.5 m long) were studied for mineralogy, major, trace and rare earth element geochemistry. Samples were analyzed at three core sections, i.e. upper (0-1 cm), middle (30-31 cm) and lower (~300-391 cm). The textural study reveals that the core sediments are characterized by silt and clay fractions. Radiocarbon dating of sediments for the cores at different levels indicated a maximum of ~28,000 year BP. Sediments were classified as shale. The chemical index of alteration (CIA) values for the upper, middle, and lower sections revealed moderate weathering in the source region. The index of chemical maturity (ICV) and SiO2/Al2O3 ratio indicated low compositional maturity for the core sediments. A statistically significant correlation observed between total rare earth elements (∑REE) versus Al2O3 and Zr indicated that REE are mainly housed in detrital minerals. The North American Shale Composite (NASC) normalized REE patterns, trace element concentrations such as Cr, Ni and V, and the comparison of REE concentrations in sediments and source rocks indicated that the study area received sediments from rocks intermediate between felsic and mafic composition. The enrichment factor (EF) results indicated that the Cd and Zn contents of the upper section sediments were influenced by an anthropogenic source. The trace element ratios and authigenic U content of the core sediments indicated the existence of an oxic depositional environment.

What Role do Nor'Easters have on the Jamaica Bay Wetlands Sediment Budget?

NASA Astrophysics Data System (ADS)

Clarke, R. C.; Bentley, S. J.; Wang, H.; Smith, J.

2017-12-01

The wetlands of Jamaica Bay, located on the outskirts of Queens, New York, have lost over half their surface area in the last 50 years due both anthropogenic and natural causes, including channel dredging, urban drainage construction, and greater tidal amplitudes partially due to rising local sea levels. Superstorm Sandy made landfall in 2014 as a powerful coastal geomorphic agent, highlighting the vulnerability of that region to large cyclonic storms that are more commonly encountered along coastal reaches of southeastern North America. After this event, research aimed at quantifying the geomorphic impact of Superstorm Sandy and to evaluate the record of past documented major winter storms on Jamaica Bay's wetlands. 12 sediment cores were collected from the surface of remaining wetlands in August 2014 by the USGS Wetland and Aquatic Research Center; the cores have been analyzed for Pb-210/Cs-137 geochronology, organic content, and water content to establish chronology of mineral sediment supply to the wetlands over the past 120 years. Most cores were found to be organic-rich, marked with periodic cm-scale beds with increased mineral content. Historic storm data, dating as far back as the late 1800's, were used to identify hurricanes and major winter storms determined by the National Weather Service passing within 100 km of the study area. Likely storm-event deposits in each core were identified as layers with mineral content higher than the core mean plus one standard deviation, and were matched to historic events via radioisotope geochronology, incorporating age-model uncertainty. Overall, 22 out of the 35 defined storm layers match the timing of historic strong storms (within uncertainty ranging from 2 to 5 years) from 1894 to Superstorm Sandy in 2014. Our findings show that over multidecadal timescales, nor'easters and winter storms play a role in the vertical accretion of sediment in the Jamaica Bay wetlands, but are substantially less important than sediment delivery under typical tidal conditions. Event deposits from tropical cyclones are also present, but less common than those produced by frontal storms.

Mineralogic Causes of Variations in Magnetic Susceptibility of Late Pleistocene and Holocene Sediment from Great Salt Lake, Utah

USGS Publications Warehouse

Reynolds, Richard L.; Rosenbaum, Joseph G.; Thompson, Robert S.

2008-01-01

We describe here results of magnetic susceptibility (MS) measurements and magnetic mineralogy of sediments sampled in three cores from the south basin of Great Salt Lake. The cores were obtained in 1996 with a Kullenburg-type piston corer at sites in close proximity: core 96-4 at 41 deg 01.00' N, 112 deg 28.00' W and cores 96-5 and 96-6 at 41 deg 00.09' N, 112 deg 23.05' W. Cores 96-5 (2.16 m long) and -6 combine to make a composite 11.31-m sediment record. Sediments in core 96-4 (5.54 m long) correspond to the approximate depth interval of 3.9-9.6 m in the composite core of 96-5 and -6 based on similarities in the MS records as described below. The central goal of the research was to provide a sediment record of paleoenvironmental change in the northeastern Basin and Range Province over the past 40,000 years. Specific targets included a sedimentologic record of lake-level change combined with a pollen record of climatic change.

The Geologic History of Lake of the Woods, Minnesota, Reconstructed Using Seismic-Reflection Imaging and Sediment Core Analysis

NASA Astrophysics Data System (ADS)

Hougardy, Devin D.

The history of glacial Lake Agassiz is complex and has intrigued researchers for over a century. Over the course of its ˜5,000 year existence, the size, shape, and location of Lake Agassiz changed dramatically depending on the location of the southern margin of the Laurentide Ice Sheet (LIS), the location and elevation of outflow channels, and differential isostatic rebound. Some of the best-preserved sequences of Lake Agassiz sediments are found in remnant lake basins where erosional processes are less pronounced than in adjacent higher-elevation regions. Lake of the Woods (LOTW), Minnesota, is among the largest of the Lake Agassiz remnant lakes and is an ideal location for Lake Agassiz sediment accumulation. High-resolution seismic-reflection (CHIRP) data collected from the southern basin of LOTW reveal up to 28 m of stratified lacustrine sediment deposited on top of glacial diamicton and bedrock. Five seismic units (SU A-E) were identified and described based on their reflection character, reflection configuration, and external geometries. Three prominent erosional unconformities (UNCF 1-3) underlie the upper three seismic units and indicate that deposition at LOTW was interrupted by a series of relatively large fluctuations in lake level. The lowermost unconformity (UNCF-1) truncates uniformly draped reflections within SU-B at the margins of the basin, where as much as four meters of sediment were eroded. The drop in lake level is interpreted to be contemporaneous with the onset of the low-stand Moorhead phase of Lake Agassiz identified from subaerial deposits in the Red River Valley, Rainy River basin, and Lake Winnipeg. A rise in lake level, indicated by onlapping reflections within SU-C onto UNCF-1, shifted the wave base outwards and as much as 11 m of sediment were deposited (SU-C) in the middle of the basin before a second drop, and subsequent rise, in lake level resulted in the formation of UNCF-2. Reflections in the lower part of SU-D onlap onto UNCF-2 only near the margins of the basin, suggesting that water occupied much of the middle of the southern basin after lake level drawdown. The reflection character and configuration of SU-C and SU-D are genetically different indicating that the depositional environment had changed following the formation of UNCF-2. Piston-type sediment cores collected from the southern basin of LOTW at depths that correspond to the middle of SU-D contain high amounts of organic material and charcoal fragments and sediment that are probably not related to Lake Agassiz. Instead, they were likely deposited during a transitional phase between when Lake Agassiz left the LOTW basin (UNCF-2) and inundation of LOTW from the northern basin due to differential isostatic rebound (UNCF-3). All sediment cores collected from the southern basin of LOTW record the uppermost unconformity, analogous in depth to UNCF-3 in the seismic images, which separates modern sediments from mid to late-Holocene sediments. The lithology of sediments below this unconformity varies across the basin from gray clay to laminated silt and clay. Radiocarbon ages from two peat layers immediately below the unconformity indicate that subaerial conditions had existed prior to the formation of UNCF-1, at about 7.75 ka cal BP. The timing correlates well with other lakes in the upper Midwest that record a prolonged dry climate during the mid-Holocene. UNCF-3 is planar and erosional across the entire survey area but erosion is greatest in the northern part of the basin as the result of a southward transgressing wave base driven by differential isostatic rebound. Deposition in the southern basin probably resumed around 3.3 ka cal BP, though no radiocarbon dates were collected directly above UNCF-3. The lithology of sediment above UNCF-3 is highly uniform across the basin and represents modern sedimentation. Late-Holocene sedimentation rates were calculated at about 0.9 mm year-1 and are roughly double the sedimentation rates in the NW Angle basin, suggesting that erosion of the southern shoreline contributes significantly to deposition in the southern basin.

The PASADO core processing strategy — A proposed new protocol for sediment core treatment in multidisciplinary lake drilling projects

NASA Astrophysics Data System (ADS)

Ohlendorf, Christian; Gebhardt, Catalina; Hahn, Annette; Kliem, Pierre; Zolitschka, Bernd

2011-07-01

Using the ICDP (International Continental Scientific Drilling Program) deep lake drilling expedition no. 5022 as an example, we describe core processing and sampling procedures as well as new tools developed for subsampling. A manual core splitter is presented that is (1) mobile, (2) able to cut plastic core liners lengthwise without producing swarf of liner material and (3) consists of off-the-shelf components. In order to improve the sampling of sediment cores, a new device, the core sampling assembly (CSA), was developed that meets the following targets: (1) the partitioning of the sediment into discs of equal thickness is fast and precise, (2) disturbed sediment at the inner surface of the liner is discarded during this sampling process, (3) usage of the available sediment is optimised, (4) subsamples are volumetric and oriented, and (5) identical subsamples are taken. The CSA can be applied to D-shaped split sediment cores of any diameter and consists of a divider and a D-shaped scoop. The sampling plan applied for ICDP expedition 5022 is illustrated and may be used as a guideline for planning the efficient partitioning of sediment amongst different lake research groups involved in multidisciplinary projects. For every subsample, the use of quality flags is suggested (1) to document the sample condition, (2) to give a first sediment classification and (3) to guarantee a precise adjustment of logging and scanning data with data determined on individual samples. Based on this, we propose a protocol that might be applied across lake drilling projects in order to facilitate planning and documentation of sampling campaigns and to ensure a better comparability of results.

Event-based washload transport and sedimentation in and around flood bypasses: Case study from the Sacramento Valley, California

NASA Astrophysics Data System (ADS)

Singer, M. B.; Aalto, R. A.

2005-05-01

In large river systems, suspended sediment transport and deposition patterns are often affected by channel constraints engineered for flood conveyance or navigation. Such managed channels typically have a limited number of overflow loci through which suspended sediment enters the river's floodplain. Engineered flood bypasses are narrow relic floodplains that are supplied by overflow diversion weirs along managed river channels, and support agriculture and complex aquatic and riparian habitats that are sensitive to the delivery of floods, fine sediment, and adsorbed contaminants. They function as wide, shallow conveyance channels parallel to the main river, and therefore present an opportunity to assess the applicability of existing theory for delivery to and settling of suspended sediment within floodplains. This study is an investigation of hydrograph characteristics, sediment delivery, and sedimentation within the upstream reaches of flood bypasses closest to the weir. We present analysis of hydrologic and sediment records and modeling in the Sacramento River basin. The effects of a single large flood in 1964-1965 were analyzed by documenting hydrograph characteristics, computing event-based sediment discharges and reach erosion/deposition through the bypass system, modeling bypass deposition, and comparing modeled results near the weirs with dated sediment cores. The rapidly rising, slowly declining 1964 flood was generated by storm runoff in the Sierra Nevada. The modeling results indicate: washload discharge through the lower valley 0.5 to 1.7 times long-term annual averages; mainstem reach erosion/deposition 0.5 to 1.25 times annual averages; and centimeter scale deposition in flood bypasses. The results are corroborated by a set of sediment cores extracted from Sacramento Valley bypasses, which were dated with 210Pb geochronology and analyzed for grain size. The modeling and data suggest net sediment accumulation between the channel and flood weirs and in the `hydraulic shadow' of the flood weir, the length of which varies depending on flow and sediment characteristics. Net accumulation in the hydraulic shadow is hypothesized to be associated with infrequent, episodic erosion of stored upland mining legacy sediments. As a result, more frequent, relatively clear-water flooding erodes prior bypass sediment deposits at the downstream end of the hydraulic shadow and propagates upstream toward the weir. Such sediment remobilization and scour events were extensively documented in our cores and have implications for the fate and transport of contaminants such as mercury, left over from decades of foothill mining, and for sediment and contaminant delivery to the Sacramento-San Francisco Bay-Delta. The modeling and field data highlighted shortcomings in conventional theory for event-based sediment concentration profiles and particle settling. These limitations could be addressed with appropriate data collection and model revision to account for the processes of sediment transport over weirs and into flood conveyance channels.

Assessment of shallow methane (CH4) gas using stable carbon and hydrogen isotopes in the sediments of the Gunsan Basin, eastern-central Yellow Sea, off the southwest of Korea

NASA Astrophysics Data System (ADS)

Lee, J. H.; Jeong, K. S.; Woo, H. J.; Kang, J.; Tsunogai, U.

2016-12-01

In the Gunsan Basin, eastern-central Yellow Sea (YS), gas seepages were observed from the uppermost sedimentary layer charged locally with gases that are important indicators of marine resources, environmental changes, and geo-hazards. Methane (CH4) among the gases is the most abundant organic compound in the Earth's atmosphere, where it acts as a greenhouse gas and thus has implications for global climate change. Headspace CH4 was determined in surface and core sediments in order to understand the C- and H- isotopes signatures in the Gunsan Basin that were collected onboard R/V Onnuri and Eardo in 2013 to 2015. The surface sediments contain 0.2 to 16.9 µM CH4 that are mostly produced by microbial fermentation of organic materials in shallow depth, as indicated by the light values of δ13CCH4 (-70.2 -50.7‰ VPDB). CH4 is actively seeping mainly in the western central part of the Gunsan Basin where the underlying sedimentary layers are thick and heavily faulted. In the cores, CH4 is concentrated 1 to 20 μM through the core depths without any relationships to grain size, organic matter contents. Largely different from those, δ13CCH4 ranges in -62.0 -18.0‰ VPDB (δ2DCH4 range in -296.0 -144.0‰ VSMOW), that is, strongly mixed CH4 of thermogenic and biogenic origins in the core sediments. The CH4 flux at the sediment-water interface (SWI) using Fick's first law of diffusion was calculated 2 29 µM·m-2·day-1 (12 µM·m-2·day-1 on the average) by a careful examination of methane distribution within the uppermost 10 cm sediment layer of 8 box cores. It seems that CH4 flux into the water layer in the Gunsan Basin is less significant than other seep areas such as of the Black Sea, Gulf of Mexico, the Bohai Sea. However, detailed and repeated CH4 observation is needed in the Gunsan Basin, as suggested by temporarily but active gas seepage in a wide regional scale.

Stepped-combustion 14C dating of bomb carbon in lake sediment

USGS Publications Warehouse

McGeehin, J.; Burr, G.S.; Hodgins, G.; Bennett, S.J.; Robbins, J.A.; Morehead, N.; Markewich, H.

2004-01-01

In this study, we applied a stepped-combustion approach to dating post-bomb lake sediment from north-central Mississippi. Samples were combusted at a low temperature (400 ??C) and then at 900 ??C. The CO2 was collected separately for both combustions and analyzed. The goal of this work was to develop a methodology to improve the accuracy of 14C dating of sediment by combusting at a lower temperature and reducing the amount of reworked carbon bound to clay minerals in the sample material. The 14C fraction modern results for the low and high temperature fractions of these sediments were compared with well-defined 137Cs determinations made on sediment taken from the same cores. Comparison of "bomb curves" for 14C and 137Cs indicate that low temperature combustion of sediment improved the accuracy of 14C dating of the sediment. However, fraction modern results for the low temperature fractions were depressed compared to atmospheric values for the same time frame, possibly the result of carbon mixing and the low sedimentation rate in the lake system.

Sediment oxygen profiles in a super-oxygenated antarctic lake

NASA Technical Reports Server (NTRS)

Wharton, R. A. Jr; Meyer, M. A.; McKay, C. P.; Mancinelli, R. L.; Simmons, G. M. Jr; Wharton RA, J. r. (Principal Investigator)

1994-01-01

Perennially ice-covered lakes are found in the McMurdo Dry Valleys of southern Victoria Land, Antarctica. In contrast to temperate lakes that have diurnal photic periods, antarctic (and arctic) lakes have a yearly photic period. An unusual feature of the antarctic lakes is the occurrence of O2 at supersaturated levels in certain portions of the water column. Here we report the first sediment O2 profiles obtained using a microelectrode from a perennially ice-covered antarctic lake. Sediment cores collected in January and October 1987 from Lake Hoare in Taylor Valley show oxygenation down to 15, and in some cases, 25 cm. The oxygenation of sediments several centimeters below the sediment-water interface is atypical for lake sediments and may be characteristic of perennially ice-covered lakes. There is a significant difference between the observed January and October sediment O2 profiles. Several explanations may account for the difference, including seasonality. A time-dependent model is presented which tests the feasibility of a seasonal cycle resulting from the long photoperiod and benthic primary production in sediments overlain by a highly oxygenated water column.

Trace Metals and Lead Isotopes in modern Sediments Near Rio de Janeiro, Brazil

NASA Astrophysics Data System (ADS)

Boyle, E. A.; Lazzari, L.; Wagener, A. L.; Carreira, R.; Godoy, J. M.; Noble, A.; Carrasco, G. G.; Moos, S. B.

2014-12-01

This work focuses on the export of trace metals and combustion residues from land to ocean and on the Southeast continental margin of Brazil and its historical variability using stable lead isotopes. Two sediment cores were collected, one in highly impacted Guanabara Bay and the other on the Southeast continental shelf. Continental shelf samples were analyzed for trace element concentrations [Mn (117±50 ppm), Ni (6.5±2.3 ppm), Zn (5.0±1.5), (233±46 ppm), ], Pb (5.4±2.4 ppm), as well as Cu, Ag, Cd, Sr, Ba, Tl, U and Pb isotope ratios & Pb-210. Most of the elements show higher concentrations on the upper part of the core compared to the bottom. Downcore changes of the concentrations of these elements were similar. The sediments of adjacent rivers and bays around the upper section of the southeast continental shelf of Brazil are considered highly enriched with Pb, Zn, Cu and Cr such as Guanabara Bay, Sepetiba Bay and Paraíba do Sul River compared with the natural concentrations and other regions in the world. A [Pb] maximum is seen between samples from 24 to 43 cm (~8 ppm). Utilization of tetraethyl lead (TEL) gasoline in Brazil was phased out beginning in 1983 and was largely completed by 1988. Continental shelf Pb-206/Pb-207 varies between 1.174 near the core top to 1.190 at 100 cm, with a sharp difference between samples at 6 and 8 cm. Higher core top Pb, Zn, and Ni corroborate the recent anthropogenic influence on the southeast continental shelf of Brazil. For Guanabara Bay sediment samples [Pb] varies between 90 ppm near the top to 1 ppm at the bottom. Pb-206/Pb-207 varies between 1.161 near the core top to 1.165 near the bottom. Using triple isotope plots we can discern different sources of lead to the region and how these vary with time.

The paleoenvironmental and climatic record of the Common Era in core sediments of Lake Abashiri in the east part of Hokkaido, Japan

NASA Astrophysics Data System (ADS)

Seto, K.; Katsuki, K.; Yamada, K.; Sonoda, T.; Kawajiri, T.; Watanabe, T.

2014-12-01

In the coastal area of the Sea of Okhotsk in the east part of Hokkaido located to for subarctic zone, many brackish-water lakes are distributed. Lake Abashiri has a distinct halocline around 5m depths, and is divided into oligohaline epilimnion and polyhaline hypolimnion by its pycnocline. In this study, paleoenvironmental and climatic changes of the Common Era in Abashiri region is discussed by sedimentologic and geochemical high-resolution analysis of the sediment cores collected from the Lake Abashiri. The 13AB-B1 core collected from Lake Abashiri shows the length of 27m. This core is composed of muddy sediment with a distinct lamination up to 19.31m below surface. The Ta-a tephra (AD 1739), Ko-c2 tephra (AD 1694) and Ma-b tephra (10th century) are found at the horizon of 2.65m, 2.91m, and 6.19m below surface, respectively. Sedimentation rate based on these ages was 5.7mm/yr between Ko-c2 tephra and Ta-a tephra, and was 4.7mm/yr between Ma-b tephra and Ko-c2 tephra. The environment of bottom water indicates the anoxic and/or euxinic conditions during the Common Era. 　The result of observation used by Soft X-ray photograph, the lamina-set of high, low, intermediate density layers was observed. High-density layers have characteristics of low TOC, low SiO2, and high Al contents. This is suggested that high-density layer is formed by the supply of inorganic clastics. The lamina set of 44 was recognized between Ko-c2 tephra and Ta-a tephra in the 10AB-5C core. This is suggested that this set is annual lamina (varve). If its so, it is considered that high density layer indicate the high precipitation term of summer season judging from precipitation pattern in Abashiri Area during 100 years. Particularly, the year of flood events tend to show a thick and distinguished layer in lamina-set. The 13AB-B core is correlated with 10AB-5C core under the lamina level. The high-density lamina-set group is repeated with 20 to 30 year cycle. The horizon of high-density lamina-set group is correlated with the term showing several years continuously high precipitation. This lamina-set group is observed from 400 years ago, the climate system would have been continued. There seems to be high-low density cycle of some order before this time. It is consider that this cycle is related to the rainfall pattern over the medium to long term.

Spatial distributions and deposition chronology of short chain chlorinated paraffins in marine sediments across the Chinese Bohai and Yellow Seas.

PubMed

Zeng, Lixi; Chen, Ru; Zhao, Zongshan; Wang, Thanh; Gao, Yan; Li, An; Wang, Yawei; Jiang, Guibin; Sun, Liguang

2013-10-15

As the most complex halogenated contaminants, short chain chlorinated paraffins (SCCPs) are scarcely reported in marine environments. In this work, a total of 117 surficial sediment (0-3 cm) samples and two sediment cores were collected from the Chinese Bohai and Yellow Seas to systematically study the spatial and temporal trends of SCCPs at a large scale in the Chinese marine environment. Total SCCP concentrations in the surficial sediments were in the range of 14.5-85.2 ng g(-1) (dry weight, d.w.) with an average level of 38.4 ng g(-1) d.w. Spatial distribution showed a decreasing trend with the distance from the coast to the open waters. Compositional pattern analysis suggested that C10 was the most predominant homologue group, followed by C11, C12, and C13 homologue groups. The concentrations of total SCCPs in sediment cores ranged from 11.6 to 94.7 ng g(-1) d.w. for YS1 and from 14.7 to 195.6 ng g(-1) d.w. for YS2, with sharp rise from the early 1950s to present based on (210)Pb dating technique. The historical records in cores correspond well to the production and usage changes of CPs in China. Multivariate regression statistics indicate TOC, latitude and longitude are the major factors influencing surficial SCCP levels in the Chinese East Seas by combining analysis with the data from the East China Sea (R(2) = 0.332, p < 0.01). These findings indicated that the sources of SCCPs were mainly from river outflows via ocean current and partly from atmospheric depositions by East Asian monsoon in the sampling areas.

210Po/210Pb Activity Ratios as a Possible `Dating Tool' of Ice Cores and Ice-rafted Sediments from the Western Arctic Ocean - Preliminary Results

NASA Astrophysics Data System (ADS)

Krupp, K.; Baskaran, M. M.

2016-02-01

We have collected and analyzed a suite of surface snow samples, ice cores, ice-rafted sediments (IRS) and aerosol samples from the Western Arctic for Po-210 and Pb-210 to examine the extent of disequilibrium between this pair to possibly use 210Po/210Pb activity ratio to date different layers of ice cores and time of incorporation of ice-rafted sediments into the sea ice. We have earlier reported that the activity concentrations of 210Pb in IRS vary over an order of magnitude and it is 1-2 orders of magnitude higher than that of the benthic sediments (1-2 dpm/g in benthic sediments compared to 25 to 300 dpm/g in IRS). In this study, we have measured 210Po/210Pb activity ratios in aerosols from the Arctic Ocean to constrain the initial 210Po/210Pb ratio at the time of deposition during precipitation. The 210Po activity concentration in recent snow is compared to surface ice samples. The `age' of IRS incorporation can be calculated as follows: [210Po]measured = [210Po]initial + [210Pb] (1 - exp(-λt)) (1) where λ is the decay constant of 210Po, 138.4 days, and `t' is the in-growth time period. From this equation, `t' can be calculated as follows: t = (-1/λ) [ln (1- ((210Po/210Pb)measured - (210Po/210Pb)initial)] (2) The assumption involved in this approach are: i) there is no preferential uptake of 210Po (highly biogenic - S group); and iii) both 210Po and 210Pb remain as closed system. The calculated age using equation (2) will be discussed and presented.

Biogeochemical cycles at the sulfate-methane transition zone (SMTZ) and geochemical characteristics of the pore fluids offshore southwestern Taiwan

NASA Astrophysics Data System (ADS)

Hu, Ching-Yi; Frank Yang, Tsanyao; Burr, George S.; Chuang, Pei-Chuan; Chen, Hsuan-Wen; Walia, Monika; Chen, Nai-Chen; Huang, Yu-Chun; Lin, Saulwood; Wang, Yunshuen; Chung, San-Hsiung; Huang, Chin-Da; Chen, Cheng-Hong

2017-11-01

In this study, we used pore water dissolved inorganic carbon (DIC), SO42-, Ca2+ and Mg2+ gradients at the sulfate-methane transition zone (SMTZ) to estimate biogeochemical fluxes for cored sediments collected offshore SW Taiwan. Net DIC flux changes (ΔDIC-Prod) were applied to determine the proportion of sulfate consumption by organic matter oxidation (heterotrophic sulfate reduction) and anaerobic oxidation of methane (AOM), and to determine reliable CH4 fluxes at the SMTZ. Our results show that SO42- profiles are mainly controlled by AOM rather than heterotrophic sulfate reduction. Refinement of CH4 flux estimates enhance our understanding of methane abundance from deep carbon reservoirs to the SMTZ. Concentrations of chloride (Cl-), bromide (Br-) and iodide (I-) dissolved in pore water were used to identify potential sources that control fluid compositions and the behavior of dissolved ions. Constant Cl- concentrations throughout ∼30 m sediment suggest no influence of gas hydrates for the compositions within the core. Bromide (Br-) and Iodine (I-) concentrations increase with sediment depth. The I-/Br- ratio appears to reflect organic matter degradation. SO42- concentrations decrease with sediment depth at a constant rate, and sediment depth profiles of Br- and I- concentrations suggests diffusion as the main transport mechanism. Therefore diffusive flux calculations are reasonable. Coring sites with high CH4 fluxes are more common in the accretionary wedge, amongst thrust faults and fractures, than in the passive continental margin offshore southwestern Taiwan. AOM reactions are a major sink for CH4 passing upward through the SMTZ and prevent high methane fluxes in the water column and to the atmosphere.

Multiple ash layers in late Quaternary sediments from the Central Indian Basin

NASA Astrophysics Data System (ADS)

Mascarenhas-Pereira, M. B. L.; Nagender Nath, B.; Iyer, S. D.; Borole, D. V.; Parthiban, G.; Jijin, R.; Khedekar, V.

2016-04-01

We have investigated three sediment cores collected from water depths > 5000 m along the transect 76°30‧E in close proximity to a fracture zone in the Central Indian Basin (CIB). The cores yielded five volcanic horizons of which four have visual and dispersed shards. Rhyolitic glass shards of bubble wall, platy, angular and blocky types were retrieved from various stratigraphic horizons in the cores. The abundance of glass shards, composition of bulk sediments, and 230Thexcess ages of the host sediments were used to distinguish the volcanic horizons. Of the four volcanic horizons, three are now newly reported and correspond to ages of ~ 85, 107-109 and 142-146 ka while the fourth horizon is of 70-75 ka. By using trace element ratios and Cr and Nb-based normative calculations, cryptotephra has been identified for the first time from the CIB sediment. The cryptotephra forms the fifth ash horizon and is of ~ 34 ka. A comparison with the published data on volcanic tephra in and around the Indian Ocean indicate the shard rich horizon (SRH) of 70-75 ka to resemble the Younger Toba Tuffs (YTT), while the other volcanic horizons that were deposited during different time periods do not correlate with any known marine or terrestrial records. These tephra layers have produced a tephrostratigraphic framework across the tectonically and volcanically complex regions of the CIB. Due to the lack of terrestrial equivalents of these tephra, it is hypothesized that the newly found volcanic horizons may have been derived from submarine volcanic eruptions. Multiple layers of submarine volcaniclastic deposits found at water depths as great as 5300 m reaffirm the growing belief that submarine phreatomagmatic eruptions are much more common in the intraplate region of the Indian Ocean than previously reported.

Sediment composition and texture of Pleistocene deep-sea turbidites in the eastern Nankai Trough gas hydrate field

NASA Astrophysics Data System (ADS)

Egawa, K.; Nishimura, O.; Izumi, S.; Ito, T.; Konno, Y.; Yoneda, J.; Jin, Y.; Kida, M.; Suzuki, K.; Nakatsuka, Y.; Nagao, J.

2013-12-01

In the 2012 JOGMEC/JAPEX pressure coring operation, we collected a totally 60-m-long core sample from the interval of gas hydrate concentration zone at the planned site of the world's first offshore production test of natural gas hydrates in the eastern Nankai Trough area. In this contribution, the cored sediments were sedimentologically, mineralogically, and paleontologically analyzed to know sediment composition and texture of reservoir formation, which are known to provide useful geological information to discuss sedimentation, diagenesis, and permeability. The targeted interval belongs to a Middle Pleistocene deep-sea turbidite sequence distributed around the Daini Atsumi Knoll, east of the Kumano forearc basin, and consists of the lower (thick sand-dominant), middle (thin-bedded sand-and-mud alteration), and upper (mud-dominant) formations in ascending order. X-ray powder diffraction analysis and scanning electron microscopic observation revealed that pore space in turbidite sands is commonly filled with clay fractions (mostly phyllosilicates) in the lower formation. Such a pore filling of clay fractions is reflected in particle size distribution showing high standard deviation and clay content, and thus is expected to have an impact on permeability. There is the older Pliocene to Early Pleistocene fossil coccolith record in the middle formation, indicating sediment reworking probably induced by submarine landslide. The coexistence of authigenic siderite and framboidal pyrite in the middle formation strongly suggests anoxic microbial activity under methane oxidation and sulfide reduction conditions at least before the hydrate cementation. This contribution was financially supported by the Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium) planned by the Ministry of Economy, Trade and Industry (METI).

Preliminary Facies Reconstruction of a Late Pleistocene Cypress Forest Discovered on the Northern Gulf of Mexico Continental Shelf

NASA Astrophysics Data System (ADS)

Gonzalez Rodriguez, S. M.; Bentley, S. J.; DeLong, K. L.; Xu, K.; Caporaso, A.; Obelcz, J. B.; Harley, G. L.; Reese, C. A.; Truong, J. T.

2016-12-01

We are investigating the origin and preservation of an ancient bald cypress forest (Taxodium distichum) discovered on the continental shelf seafloor, offshore of Gulf Shores, Alabama, USA, in 20 m water depth. The forest was likely buried in the late Pleistocene, possibly exhumed by Hurricane Ivan in 2004, and is now exposed as stumps in life position with little evidence of decay before recent marine exposure. Radiocarbon analyses show that the forest age is near (and in some cases beyond) the limits of 14C dating, at least 41-45 ky BP. In August 2015 and July 2016, submersible vibracores (up to 5 m in length) were collected. Ongoing core analyses include: organic content (loss on ignition), granulometry, and core logging using a Geotek Multi Sensor Core Logger to generate imagery, bulk density, and x-ray fluorescence data. To bolster 14C analyses, cores collected in 2016 are presently being dated using optically stimulated luminescence. Local stratigraphy consists of a surface facies of Holocene transgressive sands, underlain by possible estuarine sediments of interbedded sand and mud (potentially Holocene or Pleistocene), overlying a swamp or delta plain facies (likely Pleistocene) containing woody debris and mud. Deeper woody facies are thought to include the soil horizons of the ancient cypress forest. Cores collected in 2016 revealed a Pleistocene paleosol beneath Holocene sands in a nearby trough. Elevation differences between swamp and paleosol horizons will be evaluated from bathymetric and subbottom data, to help characterize the preserved ancient landscape. Initial interpretation based on close proximity of Pleistocene swamp and oxidized paleosol sediments, and regional geomorphic gradients suggest that this relatively diverse assemblage of facies developed up to tens of km from the glacial-age coastline, and relatively rapid burial prevented erosion by coastal processes during the Holocene transgression thus preserving the tree stumps and wood debris.

A decline in benthic foraminifera following the deepwater horizon event in the northeastern Gulf of Mexico.

PubMed

Schwing, Patrick T; Romero, Isabel C; Brooks, Gregg R; Hastings, David W; Larson, Rebekka A; Hollander, David J

2015-01-01

Sediment cores were collected from three sites (1000-1200 m water depth) in the northeastern Gulf of Mexico from December 2010 to June 2011 to assess changes in benthic foraminiferal density related to the Deepwater Horizon (DWH) event (April-July 2010, 1500 m water depth). Short-lived radioisotope geochronologies (²¹⁰Pb, ²³⁴Th), organic geochemical assessments, and redox metal concentrations were determined to relate changes in sediment accumulation rate, contamination, and redox conditions with benthic foraminiferal density. Cores collected in December 2010 indicated a decline in density (80-93%). This decline was characterized by a decrease in benthic foraminiferal density and benthic foraminiferal accumulation rate (BFAR) in the surface 10 mm relative to the down-core mean in all benthic foraminifera, including the dominant genera (Bulimina spp., Uvigerina spp., and Cibicidoides spp.). Cores collected in February 2011 documented a site-specific response. There was evidence of a recovery in the benthic foraminiferal density and BFAR at the site closest to the wellhead (45 NM, NE). However, the site farther afield (60 NM, NE) recorded a continued decline in benthic foraminiferal density and BFAR down to near-zero values. This decline in benthic foraminiferal density occurred simultaneously with abrupt increases in sedimentary accumulation rates, polycyclic aromatic hydrocarbon (PAH) concentrations, and changes in redox conditions. Persistent reducing conditions (as many as 10 months after the event) in the surface of these core records were a possible cause of the decline. Another possible cause was the increase (2-3 times background) in PAH's, which are known to cause benthic foraminifera mortality and inhibit reproduction. Records of benthic foraminiferal density coupled with short-lived radionuclide geochronology and organic geochemistry were effective in quantifying the benthic response and will continue to be a valuable tool in determining the long-term effects of the DWH event on a larger spatial scale.

A Decline in Benthic Foraminifera following the Deepwater Horizon Event in the Northeastern Gulf of Mexico

PubMed Central

Schwing, Patrick T.; Romero, Isabel C.; Brooks, Gregg R.; Hastings, David W.; Larson, Rebekka A.; Hollander, David J.

2015-01-01

Sediment cores were collected from three sites (1000–1200 m water depth) in the northeastern Gulf of Mexico from December 2010 to June 2011 to assess changes in benthic foraminiferal density related to the Deepwater Horizon (DWH) event (April-July 2010, 1500 m water depth). Short-lived radioisotope geochronologies (210Pb, 234Th), organic geochemical assessments, and redox metal concentrations were determined to relate changes in sediment accumulation rate, contamination, and redox conditions with benthic foraminiferal density. Cores collected in December 2010 indicated a decline in density (80–93%). This decline was characterized by a decrease in benthic foraminiferal density and benthic foraminiferal accumulation rate (BFAR) in the surface 10 mm relative to the down-core mean in all benthic foraminifera, including the dominant genera (Bulimina spp., Uvigerina spp., and Cibicidoides spp.). Cores collected in February 2011 documented a site-specific response. There was evidence of a recovery in the benthic foraminiferal density and BFAR at the site closest to the wellhead (45 NM, NE). However, the site farther afield (60 NM, NE) recorded a continued decline in benthic foraminiferal density and BFAR down to near-zero values. This decline in benthic foraminiferal density occurred simultaneously with abrupt increases in sedimentary accumulation rates, polycyclic aromatic hydrocarbon (PAH) concentrations, and changes in redox conditions. Persistent reducing conditions (as many as 10 months after the event) in the surface of these core records were a possible cause of the decline. Another possible cause was the increase (2–3 times background) in PAH’s, which are known to cause benthic foraminifera mortality and inhibit reproduction. Records of benthic foraminiferal density coupled with short-lived radionuclide geochronology and organic geochemistry were effective in quantifying the benthic response and will continue to be a valuable tool in determining the long-term effects of the DWH event on a larger spatial scale. PMID:25785988

Impacts of exotic mangrove forests and mangrove deforestation on carbon remineralization and ecosystem functioning in marine sediments

USGS Publications Warehouse

Sweetman, A.K.; Middelburg, J.J.; Berle, A.M.; Bernardino, A.F.; Schander, C.; Demopoulos, A.W.J.; Smith, C.R.

2010-01-01

To evaluate how mangrove invasion and removal can modify benthic carbon cycling processes and ecosystem functioning, we used stable-isotopically labelled algae as a deliberate tracer to quantify benthic respiration and C-flow through macrofauna and bacteria in sediments collected from (1) an invasive mangrove forest, (2) deforested mangrove sites 2 and 6 years after removal of above-sediment mangrove biomass, and (3) two mangrove-free, control sites in the Hawaiian coastal zone. Sediment oxygen consumption (SOC) rates were significantly greater in the mangrove and mangrove removal site experiments than in controls and were significantly correlated with total benthic (macrofauna and bacteria) biomass and sedimentary mangrove biomass (SMB). Bacteria dominated short-term C-processing of added microalgal-C and benthic biomass in sediments from the invasive mangrove forest habitat. In contrast, macrofauna were the most important agents in the short-term processing of microalgal-C in sediments from the mangrove removal and control sites. Mean faunal abundance and short term C-uptake rates in sediments from both removal sites were significantly higher than in control cores, which collectively suggest that community structure and short-term C-cycling dynamics in habitats where mangroves have been cleared can remain fundamentally different from un-invaded mudflat sediments for at least 6-yrs following above-sediment mangrove removal. In summary, invasion by mangroves can lead to large shifts in benthic ecosystem function, with sediment metabolism, benthic community structure and short-term C-remineralization dynamics being affected for years following invader removal. ?? 2010 Author(s).

Distribution of short chain chlorinated paraffins in marine sediments of the East China Sea: influencing factors, transport and implications.

PubMed

Zeng, Lixi; Zhao, Zongshan; Li, Huijuan; Wang, Thanh; Liu, Qian; Xiao, Ke; Du, Yuguo; Wang, Yawei; Jiang, Guibin

2012-09-18

Short chain chlorinated paraffins (SCCPs) are high production volume chemicals in China and found to be widely present in the environment. In this study, fifty-one surface sediments and two sediment cores were collected from the East China Sea to study their occurrence, distribution patterns and potential transport in the marginal sea. SCCPs were found in all surface sediments and ranged from 5.8 to 64.8 ng/g (dry weight, d.w.) with an average value of 25.9 ng/g d.w. A general decreasing trend with distance from the coast was observed, but the highest value was found in a distal mud area far away from the land. The C10 homologue was the most predominant carbon chain group, followed by C11, C12, and C13 homologue groups. Significant linear relationship was found between total organic carbon (TOC) and total SCCP concentrations (R(2) = 0.51, p < 0.05). Spatial distributions and correlation analysis indicated that TOC, riverine input, ocean current, and atmospheric deposition played an important role in controlling SCCP accumulation in marine sediments. Vertical profiles of sediment cores showed that SCCP concentrations decreased from surface to the depth of 36 cm, and then slightly increased again with depth, which showed a significant positive correlation with TOC and chlorine contents (Cl%). The results suggest that SCCPs are being regionally or globally distributed by long-range atmospheric or ocean current transport.

Effects of sulfate-reducing bacteria on methylmercury at the sediment-water interface.

PubMed

Zeng, Lingxia; Luo, Guangjun; He, Tianrong; Guo, Yanna; Qian, Xiaoli

2016-08-01

Sediment cores (containing sediment and overlying water) from Baihua Reservoir (SW China) were cultured under different redox conditions with different microbial activities, to understand the effects of sulfate-reducing bacteria (SRB) on mercury (Hg) methylation at sediment-water interfaces. Concentrations of dissolved methyl mercury (DMeHg) in the overlying water of the control cores with bioactivity maintained (BAC) and cores with only sulfate-reducing bacteria inhibited (SRBI) and bacteria fully inhibited (BACI) were measured at the anaerobic stage followed by the aerobic stage. For the BAC and SRBI cores, DMeHg concentrations in waters were much higher at the anaerobic stage than those at the aerobic stage, and they were negatively correlated to the dissolved oxygen concentrations (r=-0.5311 and r=-0.4977 for BAC and SRBI, respectively). The water DMeHg concentrations of the SRBI cores were 50% lower than those of the BAC cores, indicating that the SRB is of great importance in Hg methylation in sediment-water systems, but there should be other microbes such as iron-reducing bacteria and those containing specific gene cluster (hgcAB), besides SRB, causing Hg methylation in the sediment-water system. Copyright © 2016. Published by Elsevier B.V.

Offshore sediments record the history of onshore iron ore mining in Goa State, India.

PubMed

Sebastian, Tyson; Nath, B Nagender; Naik, Sangeeta; Borole, D V; Pierre, Salou; Yazing, Armoury Kazip

2017-01-30

Environmental magnetic and geochemical analyses combined with 210 Pb dating were carried out on a sediment core off Goa from Arabian Sea to reconstruct the sedimentation history of last three and a half centuries and to investigate the impact of onshore iron ore mining on the offshore sedimentation. A drastic increase in sedimentation rate and mineral magnetic concentration parameters divides the core into two units (1 & 2) at a depth of 41cm (1982CE). The high magnetic susceptibility values in Unit 1 sediments are coeval with increased iron ore production on land and illustrate the role of terrestrial mining on the increased offshore sedimentation. The early diagenetic signals were observed in Unit 2 of the core with low concentration parameters, coarse magnetic grain size and magnetically hard mineralogy. The geochemical data of the core also record the Little Ice Age (LIA) climatic events of Dalton and Maunder solar minima. Copyright © 2016 Elsevier Ltd. All rights reserved.

Near-bottom pelagic bacteria at a deep-water sewage sludge disposal site.

PubMed

Takizawa, M; Straube, W L; Hill, R T; Colwell, R R

1993-10-01

The epibenthic bacterial community at deep-ocean sewage sludge disposal site DWD-106, located approximately 106 miles (ca. 196 km) off the coast of New Jersey, was assessed for changes associated with the introduction of large amounts of sewage sludge. Mixed cultures and bacterial isolates obtained from water overlying sediment core samples collected at the deep-water (2,500 m) municipal sewage disposal site were tested for the ability to grow under in situ conditions of temperature and pressure. The responses of cultures collected at a DWD-106 station heavily impacted by sewage sludge were compared with those of samples collected from a station at the same depth which was not contaminated by sewage sludge. Significant differences were observed in the ability of mixed bacterial cultures and isolates from the two sites to grow under deep-sea pressure and temperature conditions. The levels of sludge contamination were established by enumerating Clostridium perfringens, a sewage indicator bacterium, in sediment samples from the two sites. The results of hybridization experiments in which DNAs extracted directly from the water overlying sediment core samples were used indicate that the reference site epibenthic community, the disposal site epibenthic community, and the community in a surface sludge plume share many members. Decreased culturability of reference site mixed cultures in the presence of sewage sludge was observed. Thus, the culturable portions of both the autochthonous and allochthonous bacterial communities at the disposal site may be inhibited in situ, the former by sewage sludge and the latter by high pressure and low temperature.

Analysis of elements in lake sediment samples by PIXE spectrometry

NASA Astrophysics Data System (ADS)

Chelarescu, E. D.; Radulescu, C.; Stihi, C.; Bretcan, P.; Tanislav, D.; Dulama, I. D.; Stirbescu, R. M.; Teodorescu, S.; Bucurica, I. A.; Andrei, R.; Morarescu, C.

2017-09-01

This work aims to determine the concentrations of several elements (e.g. Pb, Ni, Zn, Mn, Cr, and Fe) from lake sediments, in order to characterize their origin and evolution. Particle Induced X-ray Emission (PIXE) technique using the 3 MV Tandetron™ particle accelerator from National Institute for R&D in Physics and Nuclear Engineering "Horia Hulubei" (IFIN-HH), Magurele-Bucharest, Romania, was applied. Sediment cores from different salt lakes from Romania (i.e. Amara Lake, Caineni Lake, and Movila Miresii Lake) were collected, in August 2015. The content of Pb, Cr, Mn, Fe, and Ni from sediment samples show similarities with other data presented in literature and international regulation. The Zn was the only element with a higher content in all samples (e.g. maximum 401.7-517.3 mg/kg d.w.).

Investigation of mechanical properties of hydrate-bearing pressure core sediments recovered from the Eastern Nankai Trough using transparent acrylic cell triaxial testing system (TACTT-system)

NASA Astrophysics Data System (ADS)

Yoneda, J.; Masui, A.; Konno, Y.; Jin, Y.; Kida, M.; Suzuki, K.; Nakatsuka, Y.; Tenma, N.; Nagao, J.

2014-12-01

Natural gas hydrate-bearing pressure core sediments have been sheared in compression using a newly developed Transparent Acrylic Cell Triaxial Testing (TACTT) system to investigate the geophysical and geomechanical behavior of sediments recovered from the deep seabed in the Eastern Nankai Trough, the first Japanese offshore production test region. The sediments were recovered by hybrid pressure core system (hybrid PCS) and pressure cores were cut by pressure core analysis tools (PCATs) on board. These pressure cores were transferred to the AIST Hokkaido centre and trimmed by pressure core non-destructive analysis tools (PNATs) for TACTT system which maintained the pressure and temperature conditions within the hydrate stability boundary, through the entire process of core handling from drilling to the end of laboratory testing. An image processing technique was used to capture the motion of sediment in a transparent acrylic cell, and digital photographs were obtained at every 0.1% of vertical strain during the test. Analysis of the optical images showed that sediments with 63% hydrate saturation exhibited brittle failure, although nonhydrate-bearing sediments exhibited ductile failure. In addition, the increase in shear strength with hydrate saturation increase of natural gas hydrate is in agreement with previous data from synthetic gas hydrate. This research was financially supported by the Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium) that carries out Japan's Methane Hydrate R&D Program by the Ministry of Economy, Trade and Industry (METI).

Distribution of clay minerals in surface sediments of the western Gulf of Thailand: Sources and transport patterns

NASA Astrophysics Data System (ADS)

Shi, Xuefa; Liu, Shengfa; Fang, Xisheng; Qiao, Shuqing; Khokiattiwong, Somkiat; Kornkanitnan, Narumol

2015-06-01

A high density sampling program during two joint China-Thailand scientific cruises in 2011-2012 included collection of 152 gravity box cores in the Gulf of Thailand (GoT). Samples from the top 5 cm of each core were analyzed by X-ray diffraction for clay mineral content. Several systemic analytical approaches were applied to examine the distribution pattern and the constraint factors of clay minerals in the surface sediments of the western GoT. The clay minerals mainly comprise illite, kaolinite, chlorite and smectite, having the average weight percent distributions of 50%, 34%, 14% and 2%, respectively. Based on the spatial distribution characteristics and statistical results, the study area can be classified into three provinces. Province I contains high concentrations of smectite, and covers the northern GoT, sediments in this province are mainly from rivers discharging into the upper GoT, especially the Chao Phraya and Mae Klong Rivers. Sediments in Province II are characterized by higher values of illite, located in the central GoT, where fine sediments are contributed by the Mekong River and from the South China Sea. Province Ш, in the coastal regions of southwestern GoT close to Malaysia, exhibits a clay mineral assemblage with complex distribution patterns, and may contain terrestrial materials from the Mae Klong River as well as re-suspended sediments. Results of integrative analysis also demonstrate that the hydrodynamic environment in the study area, especially the seasonal various circumfluence and eddies, play an important role in the spatial distribution and dispersal of clay fraction in sediments.

Examining (239+240)Pu, (210)Pb and historical events to determine carbon, nitrogen and phosphorus burial in mangrove sediments of Moreton Bay, Australia.

PubMed

Sanders, Christian J; Santos, Isaac R; Maher, Damien T; Breithaupt, Joshua L; Smoak, Joseph M; Ketterer, Michael; Call, Mitchell; Sanders, Luciana; Eyre, Bradley D

2016-01-01

Two sediment cores were collected in a mangrove forest to construct geochronologies for the previous century using natural and anthropogenic radionuclide tracers. Both sediment cores were dated using (239+240)Pu global fallout signatures as well as (210)Pb, applying both the Constant Initial Concentration (CIC) and the Constant Rate of Supply (CRS) models. The (239+240)Pu and CIC model are interpreted as having comparable sediment accretion rates (SAR) below an apparent mixed region in the upper ∼5 to 10 cm. In contrast, the CRS dating method shows high sediment accretion rates in the uppermost intervals, which is substantially reduced over the lower intervals of the 100-year record. A local anthropogenic nutrient signal is reflected in the high total phosphorus (TP) concentration in younger sediments. The carbon/nitrogen molar ratios and δ(15)N values further support a local anthropogenic nutrient enrichment signal. The origin of these signals is likely the treated sewage discharge to Moreton Bay which began in the early 1970s. While the (239+240)Pu and CIC models can only produce rates averaged over the intervals of interest within the profile, the (210)Pb CRS model identifies elevated rates of sediment accretion, organic carbon (OC), nitrogen (N), and TP burial from 2000 to 2013. From 1920 to 2000, the three dating methods provide similar OC, N and TP burial rates, ∼150, 10 and 2 g m(-2) year(-1), respectively, which are comparable to global averages. Copyright © 2015 Elsevier Ltd. All rights reserved.

A century long sedimentary record of anthropogenic lead (Pb), Pb isotopes and other trace metals in Singapore.

PubMed

Chen, Mengli; Boyle, Edward A; Switzer, Adam D; Gouramanis, Chris

2016-06-01

Reconstructing the history of metal deposition in Singapore lake sediments contributes to understanding the anthropogenic and natural metal deposition in the data-sparse Southeast Asia. To this end, we present a sedimentary record of Pb, Pb isotopes and eleven other metals (Ag, As, Ba, Cd, Co, Cr, Cu, Ni, Tl, U and Zn) from a well-dated sediment core collected near the depocenter of MacRitchie Reservoir in central Singapore. Before the 1900s, the sedimentary Pb concentration was less than 2 mg/kg for both soil and sediment, with a corresponding (206)Pb/(207)Pb of ∼1.20. The Pb concentration increased to 55 mg/kg in the 1990s, and correspondingly the (206)Pb/(207)Pb decreased to less than 1.14. The (206)Pb/(207)Pb in the core top sediment is concordant with the (206)Pb/(207)Pb signal of aerosols in Singapore and other Southeast Asian cities, suggesting that Pb in the reservoir sediment was mainly from atmospheric deposition. Using the Pb concentration in the topmost layer of sediment, the estimated atmospheric Pb flux in Singapore today is ∼1.6 × 10(-2) g/m(2) yr. The concentrations of eleven other metals preserved in the sediment were also determined. A principal component analysis showed that most of the metals exhibit an increasing trend towards 1990s with a local concentration peak in the mid-20(th) century. Copyright © 2016. Published by Elsevier Ltd.

Geochemical evidence for enhanced preservation of organic matter in the oxygen minimum zone of the continental margin of northern California during the Late Pleistocene

USGS Publications Warehouse

Dean, Walter E.; Gardner, James V.; Anderson, Roger Y.

1994-01-01

The present upper water mass of the northeastern Pacific Ocean off California has a well-developed oxygen minimum zone between 600 and 1200 m wherein concentrations of dissolved oxygen are less than 0.5 mL/L. Even at such low concentrations of dissolved oxygen, benthic burrowing organisms are abundant enough to thoroughly bioturbate the surface and near-surface sediments. These macro organisms, together with micro organisms, also consume large quantities of organic carbon produced by large seasonal stocks of plankton in the overlying surface waters, which are supported by high concentrations of nutrients within the California Current upwelling system. In contrast to modern conditions of bioturbation, laminated sediments are preserved in upper Pleistocene sections of cores collected on the continental slope at water depths within the present oxygen minimum zone from at least as far north as the California-Oregon border and as far south as Point Conception. Comparison of sediment components in the laminae with those delivered to sediment traps as pelagic marine “snow” demonstrates that the dark-light lamination couplets are indeed annual (varves). These upper Pleistocene varved sediments contain more abundant lipid-rich “sapropelic” (type II) organic matter than the overlying bioturbated, oxidized Holocene sediments. The baseline of stable carbon isotopic composition of the organic matter in these slope cores does not change with time, indicating that the higher concentrations of type II organic matter in the varved sediments represent better preservation of organic matter rather than any change in the source of organic matter.

Holocene fluctuations of Quelccaya Ice Cap, Peru based on lacustrine and surficial geologic archives

NASA Astrophysics Data System (ADS)

Stroup, J. S.; Kelly, M. A.; Lowell, T. V.; Beal, S. A.; Smith, C. A.

2013-12-01

Peru's Quelccaya Ice Cap (QIC; 13.9°S, 70.8°W, ~5200-5670 m asl) is an important site for understanding tropical paleoclimate, mainly because of annually layered ice cores that provide an ~1800 year long record of tropical paleoclimatic conditions (e.g., Thompson et al., 2013). Here, we present a detailed record of QIC fluctuations using surficial deposits and lake sediments that extend back to late glacial time. We compare the late Holocene records of QIC 10Be-dated moraines and ice core data with lake sediments from a nearby glacially fed lake to establish the framework we use to interpret a Holocene long sediment record from a glacially fed lake. We also examine sediments from a nearby non-glacial lake to constrain non-glacial clastic input. We collected two ~5 m-long sediment cores, one from Laguna Challpacocha, which is currently fed by QIC meltwater, and one from the Laguna Yanacocha, which has not received QIC meltwater since ~12.3 ka. Changes in magnetic susceptibility, loss on ignition, bulk density and X-ray fluorescence chemistry combined with 14C and 210Pb chronologies provide information about sediment transported to the lakes. Retreat from the late Holocene extent defined by the 10Be-dated moraine record (~0.52 ka) is contemporaneous with a sharp transition from organic to clastic sedimentation in the Challpacocha core at ~ 0.52 ka. This implies that glacially-sourced clastic sedimentation, as tracked by loss on ignition, Ti counts and bulk density, increased during ice cap recession. Based on these same proxy data, we suggest the following Holocene history of QIC: QIC receded from the Challpacocha basin by ~10.6 ka. Increased clastic sedimentation at 8.2 - 4.1, 3.6 - 2.7 ka and from 0.55 ka - present are interpreted as times of ice cap recession. The increased clastic sedimentation at ~8.2 - 4.1 ka is consistent with surficial deposits near the present-day ice margin that indicate that at ~7.0 - 4.6 ka QIC was smaller than at present (Buffen et al., 2009). Clastic sedimentation may reflect the glacier thermal regime. Relic plants now being uncovered by the receding QIC (Thompson et al., 2006, 2013) suggest advance of cold-based ice that did not produce significant meltwater or rock flour. Striations, also present on the landscape, indicate warm-based ice conditions, which would produce meltwater and rock flour. We suggest that these striations were likely produced during ice cap retreat. A small QIC during early and middle Holocene time and large QIC during late Holocene time is similar to the Holocene extents of many Northern Hemisphere glaciers and apparently follows the pattern of Northern Hemisphere summer insolation.

Temporal changes in lithology and radiochemistry from the back-barrier environments along the Chandeleur Islands, Louisiana: March 2012-July 2013

USGS Publications Warehouse

Marot, Marci E.; Adams, C. Scott; Richwine, Kathryn A.; Smith, Christopher G.; Osterman, Lisa E.; Bernier, Julie C.

2014-01-01

Scientists from the U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center conducted a time-series collection of shallow sediment cores from the back-barrier environments along the Chandeleur Islands, Louisiana from March 2012 through July 2013. The sampling efforts were part of a larger USGS study to evaluate effects on the geomorphology of the Chandeleur Islands following the construction of an artificial sand berm to reduce oil transport onto federally managed lands. The objective of this study was to evaluate the response of the back-barrier tidal and wetland environments to the berm. This report serves as an archive for sedimentological, radiochemical, and microbiological data derived from the sediment cores. Data are available for a time-series of four sampling periods: March 2012; July 2012; September 2012; and July 2013. Downloadable data are available as Excel spreadsheets and as JPEG files. Additional files include: ArcGIS shapefiles of the sampling sites, detailed results of sediment grain size analyses, and formal Federal Geographic Data Committee metadata.

Assessing environmental changes in Lake Shihwa, South Korea, based on distributions and stable carbon isotopic compositions of n-alkanes.

PubMed

Kim, Dahae; Kim, Jung-Hyun; Kim, Min-Seob; Ra, Kongtae; Shin, Kyung-Hoon

2018-05-04

We investigate historical environmental changes in an artificial lake, Lake Shihwa in South Korea, based on bulk (TOC, TN, C/N ratio, δ 13 C TOC , and δ 15 N TN ) and molecular (concentrations and δ 13 C of n-alkanes) parameters, by analyzing riverbank sediments (n = 12), lake surface sediments (n = 9), and lake core sediments (n = 108). Although the bulk organic parameters showed similar characteristics for all lake surface sediment samples, the distribution pattern and δ 13 C of n-alkanes revealed distinct differences between 2009 samples and 2012/2016 samples. This change of sedimentary organic matter characteristics can be attributed to operation of the tidal power plant that began in 2011, which improved lake water circulation and thus changed the lake sedimentary environment from anoxic to more oxic conditions. The vertical profiles of bulk and molecular lake sediment core records collected in 2009, especially at the site closest to the dike, showed a drastic shift around 1987, indicating that stronger anoxic sedimentary conditions prevailed after 1987. This is linked to sea dike construction in 1987, which prohibited sea-lake water exchange and thus deteriorated water quality in Lake Shihwa. We conclude that Lake Shihwa has experienced severe environmental changes due to human activities. Copyright © 2018 Elsevier Ltd. All rights reserved.

Laboratory investigation of the erosion of cohesive sediments under oscillatory flows using a synchronized imaging technique

NASA Astrophysics Data System (ADS)

Sou, In Mei; Calantoni, Joseph; Reed, Allen; Furukawa, Yoko

2012-11-01

A synchronized dual stereo particle image velocimetry (PIV) measurement technique is used to examine the erosion process of a cohesive sediment core in the Small Oscillatory Flow Tunnel (S-OFT) in the Sediment Dynamics Laboratory at the Naval Research Laboratory, Stennis Space Center, MS. The dual stereo PIV windows were positioned on either side of a sediment core inserted along the centerline of the S-OFT allowing for a total measurement window of about 20 cm long by 10 cm high with sub-millimeter spacing on resolved velocity vectors. The period of oscillation ranged from 2.86 to 6.12 seconds with constant semi-excursion amplitude in the test section of 9 cm. During the erosion process, Kelvin-Helmholtz instabilities were observed as the flow accelerated in each direction and eventually were broken down when the flow reversed. The relative concentration of suspended sediments under different flow conditions was estimated using the intensity of light scattered from the sediment particles in suspension. By subtracting the initial light scattered from the core, the residual light intensity was assumed to be scattered from suspended sediments eroded from the core. Results from two different sediment core samples of mud and sand mixtures will be presented.

Investigation of Sediment Pathways and Concealed Sedimentological Features in Hidden River Cave, Kentucky

NASA Astrophysics Data System (ADS)

Feist, S.; Maclachlan, J. C.; Reinhardt, E. G.; McNeill-Jewer, C.; Eyles, C.

2016-12-01

Hidden River Cave is part of a cave system hydrogeologically related to Mammoth Cave in Kentucky and is a multi-level active cave system with 25km of mapped passages. Upper levels experience flow during flood events and lower levels have continuously flowing water. Improper industrial and domestic waste disposal and poor understanding of local hydrogeology lead to contamination of Hidden River Cave in the early 1940s. Previously used for hydroelectric power generation and as a source of potable water the cave was closed to the public for almost 50 years. A new sewage treatment plant and remediation efforts since 1989 have improved the cave system's health. This project focuses on sedimentological studies in the Hidden River Cave system. Water and sediment transport in the cave are being investigated using sediment cores, surface sediment samples and water level data. An Itrax core scanner is used to analyze sediment cores for elemental concentrations, magnetic susceptibility, radiography, and high resolution photography. Horizons of metal concentrations in the core allow correlation of sedimentation events in the cave system. Thecamoebian (testate amoebae) microfossils identified in surface samples allow for further constraint of sediment sources, sedimentation rates, and paleoclimatic analysis. Dive recorders monitor water levels, providing data to further understand the movement of sediment through the cave system. A general time constraint on the sediment's age is based on the presence of microplastic in the surface samples and sediment cores, and data from radiocarbon and lead-210 dating. The integration of various sedimentological data allows for better understanding of sedimentation processes and their record of paleoenvironmental change in the cave system. Sediment studies and methodologies from this project can be applied to other karst systems, and have important applications for communities living on karst landscapes and their water management policies.

Sediment Cd and Mo accumulation in the oxygen-minimum zone off western Baja California linked to global climate over the past 52 kyr

USGS Publications Warehouse

Dean, W.E.; Zheng, Yen; Ortiz, J.D.; VanGeen, A.

2006-01-01

Concentrations of organic carbon (orgC), cadmium (Cd), and molybdenum (Mo) were measured in two sediment cores raised from depths of 430 and 700 m within the oxygen-minimum zone (OMZ) off southern Baja California at a temporal resolution of e10.5 kyr over the past 52 kyr. These records are supplemented with diffuse spectral reflectance (DSR) measurements obtained on board ship soon after collection at a resolution of e10.05 kyr. In the core from 700 m depth, a component extracted from the DSR data and the three geochemical proxies generally vary in concert with each other and over a wide range (4-22% orgC; 1-40 mg/kg Cd; 5-120 mg/kg Mo). Intervals of increased orgC, Cd, and Mo accumulation generally correspond to warm periods recorded in the oxygen-isotopic composition of Greenland ice, with the exception of the Bolling/Allerod which is only weakly expressed off Baja California. Concentrations of the biogenic proxies are higher in the core from 430 m depth, but erratic sediment accumulation before 15 ka precludes dating of the older intervals that are laminated and contain elevated orgC, Cd, and Mo concentrations. The new data provide further evidence of an intimate teleconnection between global climate and the intensity of the OMZ and/or productivity along the western margin of North America. On the basis of a comparison with Cd and Mo records collected elsewhere in the region, we conclude that productivity may actually have varied off southern Baja California by no more than a factor of 2 over the past 52 kyr. Copyright 2006 by the American Geophysical Union.

Mapping beneath the seafloor: AUV sub-bottom profilers, sediment thickness and resource potential

NASA Astrophysics Data System (ADS)

Yeo, I. A.; Vardy, M. E.; Holwell, D.; North, L.; Murton, B. J.

2017-12-01

Most AUV seafloor exploration focuses primarily on collecting high-resolution bathymetric and backscatter data in order to identify and map features of interest. Sub-bottom profiler data provides an essential third dimension that can illuminate not only the thickness of overlying sediment packets, but also the scale and tectonic setting of surface features. In this study we present results of high-resolution sub-bottom profiler surveys of Tropic Seamount, a 3000m tall, 40km wide, flat-topped gyot located 400km south of the Canary Islands. We show how the application of AUV derived sub-bottom profiler data can be used to assess the thickness and extent of ferromanganese crusts covering the summit and underlying thin pelagic sediment cover. Bespoke chirp signals at two altitudes were used to increase the likelihood of resolving thin (tens of cm) layers of crust. Drill cores were obtained from an ROV and used to constrain and calibrate the profiler data. The cores show variable crustal thicknesses of zero to 14 cm of FeMn crustal cover over a partially phosphoritised, vuggy, often poorly lithified limestone basement. Initial measurements of sound velocities suggest differences between the limestone basement and the crust of only a few hundred meters per second. Sub-cores, drilled from large samples collected during the cruise were analysed in the NOC Acoustic Pulse Tube and with X-Ray Computer Tomography to better understand how variations in lithology, crustal thickness, surface texture and internal structure affect the returning geoacoustic signal. We discuss the pros and cons of different surveying patterns, altitudes and chirps, the relative usefulness of sub-bottom profiler data in different environments, and the value added by sub-bottom profiler surveying as opposed to bathymetric surveying alone.

Distribution and transport of total mercury and methylmercury in mercury-contaminated sediments in reservoirs and wetlands of the Sudbury River, east-central Massachusetts

USGS Publications Warehouse

Colman, John A.; Waldron, Marcus C.; Breault, Robert F.; Lent, Robert M.

1999-01-01

Total mercury and methylmercury were measured in 4 reservoir cores and 12 wetland cores from Sudbury River. The distribution of total mercury and methylmercury in these cores was evaluated to determine the potential for total mercury and methylmercury transport from reservoir and wetlands sediments to the water column. Concentrations of methylmercury were corrected for an analytical artifact introduced during the separation distillation used in the analysis procedure. Corrected methylmercury concentrations correlated with total mercury concentrations in bulk sediment from below the top layers of reservoir and wetland cores; methylmercury concentrations at the top layers of cores were relatively high, however, and were not correlated with total mercury concentrations. Concentrations of methylmercury in pore water were positively correlated with methylmercury concentrations in the bulk sediment. High concentrations of total mercury and methylmercury in sediment (73 and 0.047 micrograms per gram dry-weight basis, respectively) contributed less to the water column in the reservoir than in the wetlands probably because of burial by low concentration sediment and differences in the processes available to transport mercury from the sediments to the water in the reservoirs, as compared to the wetlands .

Historical ecology of the northern Adriatic Sea: Field methods and coring device

NASA Astrophysics Data System (ADS)

Haselmair, Alexandra; Gallmetzer, Ivo; Tomasovych, Adam; Stachowitsch, Michael; Zuschin, Martin

2014-05-01

For an ongoing study on the historical ecology of the northern Adriatic Sea, the objective was to retrieve a high number of sediment cores at seven sampling stations spread across the entire basin. One set of cores is intended for sediment analyses including radiometric Pb-sediment-dating, grain size, TOC, TAC and heavy metal analyses. The other set of cores delivered enough shelly remains of endo- or epibenthic hard part producers (e.g. molluscs, crustaceans, echinoderms) to enable the reconstruction of death assemblages in core layers from top to bottom. The down-core changes of such assemblages record ecological shifts in a marine environment that has endured strong human impacts over several centuries. A 1.5 m-long core could, according to the available sedimentation data for the area, cover up to 2000 or even more years of ecological history. The coring method had to meet the following requirements: a) deliver 1.5-m-long cores from different sediment settings (mud to sand, reflecting a wide range of benthic habitats in the northern Adriatic); b) enable quick and easy deployment to ensure that multiple cores can be taken at the individual sampling stations within a short time; c) be relatively affordable and allow handling by the researchers themselves, potentially using a small vessel in order to further contain the operating costs. Two types of UWITEC™ piston corers were used to meet these requirements. A model with 90 mm of diameter (samples for sediment analysis) and another one with 160 mm, specifically designed to obtain the large amount of material needed for shell analysis, successfully delivered a total of 54 cores. The device consists of a stabilizing tripod and the interchangeable coring cylinders. It is equipped with a so-called hammer action that makes it possible, at least for the smaller cylinder, to penetrate even harder sediments. A closing mechanism of the corer retains the sediment in the cylinder upon extraction; it works either automatically through hydraulic pressure once the final core-length is reached, or can be triggered manually anytime from the surface using a connected hose and water pump. The whole coring device weighs less than 300 kg and can readily be transported in a van. It can easily be assembled, disassembled and operated by two to three persons after a brief training. With a newly designed, very simple and effective slicing device, the cores can be sliced in an upright position directly on board after extraction. This type of corer can be highly recommended for any smaller coring operations on lakes, streams, or at sea.

Ground Penetrating Radar, Magnetic and Compositional Analysis of Sediment Cores and Surface Samples: The Relationships Between Lacustrine Sediments and Holocene Lake- Level and Climate Change at Deming Lake, Minnesota, USA

NASA Astrophysics Data System (ADS)

Murray, R.; Lascu, I.; Plank, C.

2007-12-01

Deming Lake is a small (<1 square km), deep (about 17m), meromictic kettle lake situated near the prairie- forest boundary, in Itasca State Park, MN. Because of the lake's location and morphology, the accumulated sediments comprise a high-resolution record of limnological and ecological changes in response to Holocene climate variations. We used a shore perpendicular transect of three cores (located in littoral, mid-slope, and profundal settings) and ground penetrating radar (GPR) profiles to investigate Holocene lake-level variability at Deming. Cores were sampled continuously at a 1-2 cm resolution and sediment composition (in terms of percent organic matter, carbonate material, and minerogenic residue) was determined via loss on ignition (LOI). Isothermal remanent magnetization (IRM) and anhysteretic remanent magnetization (ARM) were used as proxies of magnetic mineral concentration and grain size. Four lithostratigraphic units were identified and correlated between cores based on these analyses. Changes in GPR facies corroborate the correlation between the two shallow cores. In order to inform our interpretation of down-core variations in magnetic properties and LOI values in terms of variations in lake depth, a suite of over 70 modern sediment samples were collected from the basin and analyzed. LOI compositional variability across the basin was high, with no clear trends related to depth or distance from shore. A sharp decrease in minerogenic content was observed at depths consistent with a predicted wave-base of 0.5 m, but aside from this trend it appears the steep slopes of much of the basin promote gravity driven slumping and mixing of sediments at depth. In the profundal sediments IRM values are routinely 5% higher than in the slope and littoral environments, while ARM/IRM ratios indicate an increase in magnetic grain size with water depth. We infer that an increase in coarse organic material in the shallow-water cores of Deming records a period of aridity (associated with a decrease lake-level less than 2m based on GPR profiles) and/or increased water clarity during the regionally expansive mid-Holocene dry period. We do not see clear evidence of late-Holocene lake level change of a significant magnitude (i.e. >1m). While remanence measurements (especially IRM) often correlate with the LOI residue, interference in the IRM resulting from the dissolution of magnetic minerals casts uncertainty into the reliability of our magnetic measurements as a signal of climate driven limnological change. Additional measurements must be performed before definite interpretations about the lake-level changes at Deming can be made. We suggest that future studies look more closely at the near-shore record (water depths <1m), as our results indicate shoreline migration in response to moisture balance fluctuations during the last 1000 years (as recorded at numerous sites in the great plains and upper Midwest) may have been subtle.

Diatom paleoecology Pass Key core 37, Everglades National Park, Florida Bay

USGS Publications Warehouse

Pyle, Laura; Cooper, S.R.; Huvane, J.K.

1998-01-01

During the 20th century, there have been large-scale anthropogenic modifications to the South Florida ecosystem. The effects of these changes on Florida Bay and its biological communities are currently of political and scientific interest. This study is part of a larger effort to reconstruct the history of environmental changes in the bay, using paleoecological techniques. We are using diatom indicators preserved in Florida Bay sediments to infer long-term water quality, productivity, nutrient, and salinity changes. We are also obtaining information concerning the natural variability of the ecosystem. Diatoms are microscopic algae, the remains of which are generally well preserved in sediments, and their distributions are closely linked to water quality. Diatoms were extracted from a 70-cm sediment core collected from the Pass Key mudbank of Florida Bay by the U.S. Geological Survey. Between 300-500 diatom valves from each of 15 core samples were identified and counted. Estimates of absolute abundance, species richness, Shannon-Wiener diversity, and centric:pennate ratios were calculated for each sample that was counted. Information on the ecology of the diatom species is presented, and changes in diatom community composition are evaluated. Samples contained an average of four million diatom valves per gram of sediment. Major changes in the diatom community are evident down core. These include increases in the percent abundance of marine diatoms in the time period represented by the core, probably the result of increasing salinity at Pass Key. Benthic diatoms become less abundant in the top half of the core. This may be related to a number of factors including the die-off of sea grass beds or increased turbidity of the water column. Once the chronology of the Pass Key core 37 is established, these down-core changes can be related to historical events and compared with other indicators in the sedimentary record that are currently being investigated by U.S Geological Survey researchers. This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Third Generation (3G) Site Characterization: Cryogenic Core Collection and High Throughput Core Analysis - An Addendum to Basic Research Addressing Contaminants in Low Permeability Zones - A State of the Science Review

DTIC Science & Technology

2016-07-29

Research Addressing Contaminants in Low Permeability Zones - A State of the Science Review SERDP Project ER-1740 JULY 2016 Tom Sale Saeed...process, or service by trade name, trademark, manufacturer , or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or...managing releases of chlorinated solvents and other persistent contaminants in groundwater in unconsolidated sediments. N/A U U U UU 126 Dr. Tom Sale 970

Towards improved cirque glacier reconstructions: differentiating glacial- from non-glacial sediments by means of environmental magnetism.

NASA Astrophysics Data System (ADS)

Kvisvik, Bjørn Christian; Paasche, Øyvind; Olaf Dahl, Svein

2014-05-01

Skriufonnen, a small cirque glacier (0.4 km2) in Southern Norway, has been monitored for the last 10 years, revealing a short response time to on-going climate change. This is the only remaining glacier in the central mountain massif known as Rondane where investigations of past climate variability are scarce. A series of short (HTH, n=8) and long (piston, n=6) cores from two lakes located downstream of Skriufonnen were retrieved and sediments were dated and analysed. In order to complement and validate lake sediment interpretations i.e., the potential connection to glacier variability, a number of soil samples was collected from the surrounding catchment. The six 110 mm piston cores (< 3.1 m length) and eight sediment surface cores were analysed for grain size distribution, geochemical elements (ITRAX XRF-scanning), organic matter content (LOI), magnetic parameters (magnetic susceptibility; surface and bulk), anhysteretic remanent magnetization (ARM) and Saturation Isothermal remanent magnetizations (sIRM). Consistent age-depth relationships were obtained by AMS-C14 and Pb210 dates showing that the cores cover at least the last 10 000 years. High-resolution analysis (XRF and MS) reveals centennial trends, but also distinct changes in frequency and amplitude. A quiescent period during the Holocene Thermal Optimum (9-6 ka) is followed by a sudden onset of Neoglacial (3.8 ka) activity peaking at 2.4 ka. The Little Ice Age (LIA) peaked at 1800 AD. A weak magnetic signal is observed in all cores. This is explained by the fact that Rondane is made of Sparagmite, an arkosic sandstone partly consisting of metamorphosed sandstone and conglomerate with high content of quarts (SiO2) (between 80 to 87 %) and Feldspar. The Sparagmite is resistant to chemical weathering, making the soils dry and sandy. Catchment sediment samples, running in a transect all the way up from the lakes to the glacier snout were sieved into various size classes (250, 125, 63, 38, 20 μm) prior to measuring bulk susceptibility (Ξbulk) at 293K and 77K. The ratio between the two measurements indicates the relative amount of paramagnetic versus ferromagnetic minerals, and results indicate not only that the finest fractions increase in strength as one gets closer to the glacier front, but also that there are long periods in the cores which is dominated by paramagnetic minerals. The approach employed here suggests that the combination of catchment samples with high-resolution analysis of lake sediment cores provide a more accurate reconstruction of past glacier variability, and has resulted in the first continuous cirque glacier reconstruction from this area.

Quantifying and tracing sediment mobilized during the 20th century in the South River watershed, western Massachusetts

NASA Astrophysics Data System (ADS)

Dow, S.; Snyder, N. P.; Ouimet, W. B.; Martini, A. M.; Yellen, B.; Woodruff, J. D.; Newton, R. M.

2016-12-01

New England has a long history of anthropogenic activity affecting the landscape, including deforestation, land use changes, and the construction of dams. Dams in particular have the ability to impound vast quantities of sediment eroded off the landscape. The South River in western Massachusetts is an example of a watershed where mill dam construction coincided with deforestation during the 17th-19th centuries, leading to the impoundment of legacy sediment. Along the river, these deposits act as a source of sediment being released back into the river. The Conway Electric Dam (CED), a 17 m tall dam built in 1906, is located downstream of the mill dams (most of which are no longer intact), and provides a 20th century depositional record for the watershed. The purpose of this study is to quantify sedimentation behind the CED and link this to erosion of upstream mill pond and glacial sediment sources using aerial photography, sediment cores, grainsize, and geochemical analyses. We used aerial photographs to map areal changes of the reservoir from 1940-1980, and topographic profiles generated from LiDAR to estimate a volume of 244,000 m3 of sediment stored behind the CED. We dated layers in cores collected at the site with Hg and 137Cs analyses. Overall, the reservoir exhibits a decreasing rate of sediment infilling occurring from 1940-1980, except for a potentially anomalous increase from 1940-1952. Discharge data containing large storm events were compared to sediment infilling rates to identify if a frequency of large storms could account for high rates of erosion and sediment transport; however, sedimentation at the site does not appear to be solely dependent on these large storm events. Preliminary Hg analyses of deposits from the watershed upstream of the CED indicate higher concentrations in mill pond sediment than glacial sediment. Ongoing work with geochemical tracers can potentially provide a robust understanding of sources and 20th century sediment mobilization in the South River watershed, allowing us to quantify the influence of two cycles of dam construction on watershed sediment transport rates.

Distribution and accumulation of polybrominated diphenyl ethers (PBDEs) in Hong Kong mangrove sediments.

PubMed

Zhu, Haowen; Wang, Ying; Wang, Xiaowei; Luan, Tiangang; Tam, Nora F Y

2014-01-15

Polybrominated diphenyl ethers (PBDEs) have been used extensively as brominated flame retardants in various polymers, and have become serious environmental contaminants, particularly in coastal sediments. Mangrove wetlands are important coastal ecosystems in tropical and subtropical regions, and mangrove sediments are often the pollutant sinks due to their close proximity with human activities. In Hong Kong, sediment samples collected from five mangrove swamps were found to be contaminated with PBDEs and the eight measured BDE congeners, including BDE-28, -47, -99, -100, -153, -154, -183 and -209 were detected in all mangrove sediments, indicating that these pollutants were widespread in Hong Kong mangrove wetlands. Among the five swamps, relatively high concentrations of PBDEs were recorded in Mai Po mangrove swamp in the northwestern Hong Kong, which is part of the RAMSAR site but is severely influenced by the pollution from the Pearl River Delta. The depth profile of PBDEs in sediment cores collected from Mai Po also showed the inputs of PBDEs in this mangrove swamp increased year by year. In all sediments, the concentrations of BDE-209 were 1-2 orders of magnitude higher than the other congeners in the same sediment. The concentrations of BDE-209 and ∑PBDEs (defined as the sum of seven targeted BDE congeners except BDE-209) ranged from 1.53 to 75.9 ng g(-1) and from 0.57 to 14.4 ng g(-1), respectively. Among the targeted BDE congeners except BDE-209, slightly different composition was recorded among samples collected from different locations, with BDE-153 and -183 being the pre-dominated congeners. In all mangrove swamps, except Tai O in the southwest of Hong Kong, ∑PBDEs concentrations showed a common trend of landward>seaward>mudflat. The concentrations of ∑PBDEs were significantly correlated with total organic matter (TOM) content in sediments but not with the sediment particle sizes in each mangrove swamp. © 2013.

Evaluation of shallow sediment methane cycling in a pockmark field on the Chatham Rise, New Zealand

NASA Astrophysics Data System (ADS)

Coffin, R. B.; Rose, P. S.; Klaucke, I.; Bialas, J.; Pecher, I. A.; Gorman, A. R.

2014-12-01

Seismic studies have identified an extensive field (>20,000 km2) of seafloor depressions, or pockmarks, on the southwestern flank of the Chatham Rise, New Zealand. It has been suggested that these pockmarks result from gas hydrate dissociation linked to sea-level changes during glacial-interglacial cycles. Gas hydrates are predominately composed of methane (CH4), a potent greenhouse gas. Surface sediment cores (~ 8 m) were collected from the pockmark field on the Chatham Rise during a research cruise in February 2013 to evaluate the association of the features with CH4 releases. A suite of geochemical parameters are interpreted to determine the methane contribution to solid phase sediment and pore water. The upward flux of CH4 in sediments is often quantified using pore water sulfate (SO42-) profiles, assuming steady-state consumption of SO42- and CH4 by anaerobic oxidation of methane (AOM): CH4 + SO42- → HCO3- + HS- + H2O. This reaction is one of the primary controls on CH4 distributions in sediments. This work will present pore water SO42-, sulfide (HS-) and chloride (Cl-) depth profiles in sediment collected from the pockmark field. Theoretical SO42- distributions in the absence of AOM are compared to observed SO42- profiles as a preliminary assessment of the influence of CH4 on sediment geochemistry in and around the seafloor depressions. In addition isotopically-light CH4 is incorporated into sediment carbon pools via AOM and subsequent CO2 fixation. Stable carbon isotope distributions in the organic and inorganic carbon pools are presented to determine the influence of CH4 in sediments in the vicinty of the pockmarks. Collectively, the geochemical data are used to assess the role of gas hydate dissociation in pockmark formation on the Chatham Rise. Despite sesimic data interpretation in this region there is no modern day contribution of CH4 to shallow sediment carbon cycling and data are presented to assess paleogeochemical methane cycling.

Ground-penetrating radar and differential global positioning system data collected from Long Beach Island, New Jersey, April 2015

USGS Publications Warehouse

Zaremba, Nicholas J.; Smith, Kathryn E.L.; Bishop, James M.; Smith, Christopher G.

2016-08-04

Scientists from the United States Geological Survey, St. Petersburg Coastal and Marine Science Center, U.S. Geological Survey Pacific Coastal and Marine Science Center, and students from the University of Hawaii at Manoa collected sediment cores, sediment surface grab samples, ground-penetrating radar (GPR) and Differential Global Positioning System (DGPS) data from within the Edwin B. Forsythe National Wildlife Refuge–Holgate Unit located on the southern end of Long Beach Island, New Jersey, in April 2015 (FAN 2015-611-FA). The study’s objective was to identify washover deposits in the stratigraphic record to aid in understanding barrier island evolution. This report is an archive of GPR and DGPS data collected from Long Beach Island in 2015. Data products, including raw GPR and processed DGPS data, elevation corrected GPR profiles, and accompanying Federal Geographic Data Committee metadata can be downloaded from the Data Downloads page.

Assessment of heavy metal contamination in core sediment samples in Gulf of Izmir, Aegean Sea, Turkey (by inductively coupled plasma-optical emission spectrometry (ICP-OES))

NASA Astrophysics Data System (ADS)

Ünal Yumun, Zeki; Kam, Erol; Kurt, Dilek

2017-04-01

Heavy metal and radionuclide analysis studies are crucial in explaining biotic and abiotic interactions in ecosystems. This type of analysis is highly needed in environments such as coastal areas, gulfs or lakes where human activities are generally concentrated. Sediments are one of the best biological indicators for the environment since the pollution accumulates in the sediments by descent to the sea floor. In this study, sediments were collected from the Gulf of Izmir (Eastern Aegean Sea, Turkey) considering the accumulated points of domestic and industrial wastes to make an anthropogenic pollution analysis. The core sediments had different depths of 0.00-30.00 m at four different locations where Karsiyaka, Bayrakli, Incialti and Cesmealti in the Gulf of Izmir. The purpose of the study was determining Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn concentrations in the drilling samples to assess their levels and spatial distribution in crucial areas of the Aegean Sea by inductively coupled plasma-optical emission spectrometry (ICP-OES) with microwave digestion techniques. The heavy metal concentrations found in sediments varied for Cd:

Nature of distribution of mercury in the sediments of the river Yamuna (tributary of the Ganges), India.

PubMed

Subramanian, V; Madhavan, N; Saxena, Rajinder; Lundin, Lars-Christer

2003-06-01

Suspended Particulate Matter (SPM), surface (bed sediments) and short length cores of sediments collected from the largest tributary of the river Ganges, namely the river Yamuna, were analysed for total mercury as well as its fractionation in various size and chemical sites in the sediments following standard procedures. Also, attempts were made to determine the vertical distribution in sediments in relation to the recent timescale of a few decades. Our observations indicate that the SPM in general showed higher levels of total mercury compared to the surface sediments while at places the enhancement could be by a factor of 10, say around 25 microg g(-1) in the downstream region that integrates the industrial midstream and agricultural downstream terrain near its confluence with the Ganges. Surface sediments in the upstream direction near the Himalayan foothills and SPM in the lower reaches showed significant high Index of Geoaccumulation (Igeo) as defined by Müller. Size fractionation studies indicate that the finer fraction preferentially showed higher levels of mercury while in the lower reaches of the river, the total mercury is equitably distributed among all size fractions. The proportion of the residual fraction of mercury in relation to mobile fractions, in general decreases downstream towards its confluence with the Ganges river. In sediment cores, the vertical distribution show systematic peaks of mercury indicating that addition of this toxic metal to the aquatic system is in direct proportion to the increase in various types of human activities such as thermal power plants, land use changes (urbanisation) in the midstream region and intensive fertiliser application in lower reaches of this vast river basin.

A Comparison of Recent Organic and Inorganic Carbon Isotope Records: Why Do They Covary in Some Settings and Not In Others?

NASA Astrophysics Data System (ADS)

Oehlert, A. M.; Swart, P. K.

2013-12-01

Covariance between inorganic and organic δ13C records has been used to determine whether a deposit has been altered by diagenesis, how the dynamics of the global carbon cycle changed during the production of the sediments in the deposit, and also for chronostratigraphic correlations. Although covariant records are observed in the ancient geologic record in a variety of depositional environments, such comparisons are not widely applied to modern deposits where definitive data regarding sediment producers, sea level fluctuations, and changes in the global carbon cycle are available. This study uses paired δ13C records from cores collected by the Ocean Drilling Program from three modern periplatform settings (the Great Bahama Bank, the Great Australian Bight, and the Great Barrier Reef), and two pelagic settings (the Walvis Ridge, and the Madingley Rise). These sites were selected in order to assess the influence of several different environmental factors including; sediment and organic matter producers, sediment mineralogy, margin architecture, sea level oscillations, and sediment transport pathways. In the three periplatform settings, multiple cores arranged in a margin to basin transect were analyzed in order to provide insights into the effects of downslope sediment transport. The preliminary results of this study suggest that sea level oscillations and margin architecture may artificially generate a covarying relationship in periplatform sediments that is unrelated to changes in the global carbon cycle. Furthermore, preliminary results from the Walvis Ridge and the Madingley Rise sediments suggest that the relationship between inorganic and organic δ13C records may not always exhibit a positive covariance as is currently assumed for pelagic carbonates.

Lithologic descriptions of two cores and ground-water-quality data from five counties in the northeastern part of the coastal plain of South Carolina, 1988 and 1991

USGS Publications Warehouse

Falls, W.F.

1994-01-01

This report presents data collected as part of a hydrologic investigation of Darlington, Dillon, Florence, Marion, and Marlboro Counties in the northeastern part of the Coastal Plain of South Carolina. These data include lithologic descriptions of sediment recovered from two continuously cored boreholes and water-quality results for samples collected from 17 existing wells. One continuously cored borehole was drilled near Lake Darpo in the northern part of Darlington County to a total depth of 447 feet below land surface. The other borehole was drilled in Lake City in the south-central part of Florence County to a total depth of 1,090 feet below land surface. Water-quality results presented in this report include specific conductance, dissolved oxygen, temperature, pH, alkalinity, major- and minor-ion chemistry, and hydrogen sulfide.

210Pb dating of sediments in a heavily contaminated drainage channel to the La Plata estuary in Buenos Aires, Argentina.

PubMed

Di Gregorio, D E; Fernández Niello, J O; Huck, H; Somacal, H; Curutchet, G

2007-01-01

Concentrations of (210)Pb and (137)Cs in sediment samples collected from two cores at a drainage channel to the La Plata river estuary in Buenos Aires, Argentina, were measured using ultralow-background detection systems. The (210)Pb data were used to determine the rate of sediment accumulation of the sites. These results were correlated with some heavy metal (chromium and lead) concentrations of the samples in an attempt to characterize the historical input of contaminants due to the industrial development, which has taken place in this area over the last century. The (137)Cs measurements demonstrate that cesium dating is not adequate in regions of the southern hemisphere.

Sedimentation and tectonics of the Sylhet trough, Bangladesh

USGS Publications Warehouse

Johnson, S.Y.; Nur Alam, A.M.

1991-01-01

The Sylhet trough, a sub-basin of the Bengal Basin in northeastern Bangladesh, contains a thick fill (12 to 16 km) of late Mesozoic and Cenozoic strata that record its tectonic evolution. Stratigraphic, sedimentologic, and petrographic data collected from outcrops, cores, well logs, and seismic lines are used to reconstruct the history of this trough. -from Authors

Towards the development of a consensual chronostratigraphy for Arctic Ocean sedimentary records

NASA Astrophysics Data System (ADS)

Hillaire-Marcel, Claude; de Vernal, Anne; Polyak, Leonid; Stein, Rüdiger; Maccali, Jenny; Jacobel, Allison; Cuny, Kristan

2017-04-01

Deciphering Arctic paleoceanograpy and paleoclimate, and linking it to global marine and atmospheric records is much needed for comprehending the Earth's climate history. However, this task is hampered by multiple problems with dating Arctic Ocean sedimentary records related notably to low and highly variable sedimentation rates, scarce and discontinuous biogenic proxies due to low productivity and/or poor preservation, and difficulties correlating regional records to global stacks (e.g., paleomagnetic). Despite recent advances in developing an Arctic Ocean sedimentary stratigraphy, and attempts at setting radiometric benchmark ages of respectively 300 and 150 ka, based on the final decay of 230Th and 231Pa excesses (Thxs, Paxs) (Not et al., 2008), consensual age models are still missing, preventing reliable integration of Arctic records in a global paleoclimatic scheme. Here, we intend to illustrate these issues by comparing consistent Thxs-Paxs chronostratigraphic records from the Mendeleev-Alpha and Lomonosov ridges with the currently used age model based on climatostratigraphic interpretation of sedimentary records (e.g., Polyak et al., 2009; Stein et al., 2010). Data used were collected from the 2005 HOTRAX core MC-11 (northern Mendeleev Ridge) and the 2014 Polarstern core PS87-30 (Lomonosov Ridge). Total collapse depths of Thxs and Paxs are observed by a factor of 3 deeper in core PS87-30 vs core MC-11, indicating average sedimentation rates 3 times higher at the Lomonosov Ridge site. Litho-biostratigraphic markers, such as foraminiferal peaks and manganese-enriched layers, show a similar pattern, with their occurrence 3 times deeper in core PS87-30 than in core MC-11. These very consistent downcore features highlight a gaping difference between the benchmark ages assigned to the total decay of Paxs and Thxs and the current age model based on climatostratigraphic approach involving significantly higher sedimentation rates. This discrepancy begs for its in-depth investigation that would potentially result in a development of the consensual chronostratigraphy for Quaternary Arctic Ocean sediments, critical for integrating the Arctic into global paleoclimatic history.

Reconstruction of the Final Phases of Activity and Retreat of the North Sea Lobe Ice Stream during the Late Devensian

NASA Astrophysics Data System (ADS)

Grimoldi, E.; Roberts, D. H.; Evans, D. J. A.; Stewart, H. A.; Sejrup, H. P.; Hjelstuen, B. O. B.; Haflidason, H.; Clark, C.

2016-12-01

The deglacial history of the former eastern margin of the last British and Irish Ice Sheet (BIIS) is still poorly understood, particularly in the western North Sea basin. The North Sea Lobe (NSL) affected the area, although gaps remain in our knowledge of the geomorphological and sedimentary imprint that the ice stream left on the seafloor and, more importantly, of its way of final retreat. In this work we analyse new high-resolution multibeam bathymetry, 2D seismic profiles and five vibro-cores, collected in the western North Sea in collaboration with the Britice-Chrono project, and provide new insights on the seafloor geomorphology and acoustic and lithological facies that characterize the Quaternary sediments of the area. The presence of bedrock-cored lineations orientated WNW-ESE to NW-SE indicates that the NSL was fed by the Forth ice stream which moved offshore from southern Scotland. Moraine ridges and two grounding zone wedges, perpendicular to the lineations, suggest that the NSL underwent different phases of stillstand/readvance and retreated towards the north-west. Five acoustic facies (AF) were identified, four of which are found on top of pre-Quaternary strata (AF 1), though their lateral extension is discontinuous. They are interpreted to represent glacigenic diamicts (AF 2 and 3), that are overlain by glacimarine (AF 4) and by Holocene deposits (AF 5). The vibro-cores penetrate in depth until reaching the top of AF 3. This facies correlates to the diamictic sediments observed in the cores, which are characterized by soft silts and clays and abundant clasts. The glacimarine sediments generally appear as highly laminated silts and clays with dropstones that usually become less frequent going upwards in the cores. These sediments are also characterized by foraminifera species associated with glacial environments. Foraminifera tests were dated within the galcimarine sequences in two cores and will help constrain the timing of ice retreat. By compiling all the available datasets, we suggest that the NSL flew sub-parallel to the coasts of eastern England during the Late Devensian and underwent different phases of stillstands/readvances that indicate a slow retreat towards land.

Isotopic signature of short term climate oscillations in the sediments of the Gulf of Gdansk (Southern Baltic Sea, Poland)

NASA Astrophysics Data System (ADS)

Paczek, Urszula; Tudyka, Konrad; Bałdys, Piotr; Pazdur, Anna

2010-05-01

The Gulf of Gdańsk is a part of the southern Baltic Sea - an intra-continental, shallow arm of the Atlantic Ocean entirely located on continental crust. The gulf occupies the area of ca. 5000 km2. Its northern border is a conventional line between the Cape Rozewie (Poland) and the Cape Taran (Russia). The Gulf of Gdańsk is under impact of inflowing salty waters from the North Sea but also there is a great effect of the Vistula River marked. The river is one of two the most important sources of material in the gulf. Cliffs erosion is the second one. The interplay of marine and land waters is multiplied by impact of two different climates - continental and maritime. The subject of intended research is a core of muddy sediments collected within the framework of project carried by the Branch of Marine Geology of the Polish Geological Institute in Gdańsk. The core was 300 cm long and was taken using Kullenberg core sampler in 2006 from the depth of 32 m. Since 2009 the research has been led in cooperation with the Department of Radioisotopes, Institute of Physics, Silesian University of Technology. In our study we use δ18O and δ13C measured in organic mater of sediments with mass spectrometer. Radiocarbon concentration was measured using gas proportional counters using organic mater . 14C dates were corrected according to isotopic fractioning with measured δ13C. We found systematic inversions of dates that were probably caused by changing of ?R (regional difference from the modeled global surface ocean reservoir age) during Baltic evolution. The attention was also paid on recognition of sedimentation process that is a very good indicator of dynamics in sedimentary environment. The grain size analysis was carried out for 300 samples using method of laser diffraction. Results showed great variability in bulk sediment composition that indicates susceptibility to changes in climatic and hydrodynamic conditions of studied area. Excluding the top ca. 30 cm of the core two clear cycles in sedimentation process may be distinguished. They are characterized by the greater contribution of thicker sediment fractions. Additionally shorter variations are also observed in both main cycles. All the results are bounded with 14C age-depth model that represents last 7500 cal BP. It covers two stages of the Baltic Sea development. According to 14C depth model two main cycles in granulation correspond to 1500 yr each. Shorter variations correspond to 550 yr each. We also noticed rapid shift in sedimentation rate that we correlate with sudden change in granulation composition occurring on ca. 30 cm of the core.

The effect of sediment thermal conductivity on vertical groundwater flux estimates

NASA Astrophysics Data System (ADS)

Sebok, Eva; Müller, Sascha; Engesgaard, Peter; Duque, Carlos

2015-04-01

The interaction between groundwater and surface water is of great importance both from ecological and water management perspective. The exchange fluxes are often estimated based on vertical temperature profiles taken from shallow sediments assuming a homogeneous standard value of sediment thermal conductivity. Here we report on a field investigation in a stream and in a fjord, where vertical profiles of sediment thermal conductivity and temperatures were measured in order to, (i) define the vertical variability in sediment thermal conductivity, (ii) quantify the effect of heterogeneity in sediment thermal conductivity on the estimated vertical groundwater fluxes. The study was carried out at field sites located in Ringkøbing fjord and Holtum stream in Western Denmark. Both locations have soft, sandy sediments with an upper organic layer at the fjord site. First 9 and 12 vertical sediment temperature profiles up to 0.5 m depth below the sediment bed were collected in the fjord and in the stream, respectively. Later sediment cores of 0.05 m diameter were removed at the location of the temperature profiles. Sediment thermal conductivity was measured in the sediment cores at 0.1 m intervals with a Decagon KD2 Pro device. A 1D flow and heat transport model (HydroGeoSphere) was set up and vertical groundwater fluxes were estimated based on the measured vertical sediment temperature profiles by coupling the model with PEST. To determine the effect of heterogeneity in sediment thermal conductivity on estimated vertical groundwater fluxes, the model was run by assigning (i) a homogeneous thermal conductivity for all sediment layers, calculated as the average sediment thermal conductivity of the profile, (ii) measured sediment thermal conductivities to the different model layers. The field survey showed that sediment thermal conductivity over a 0.5 m profile below the sediment bed is not uniform, having the largest variability in the fjord where organic sediments were also present. Using the measured sediment thermal conductivity for the different model layers instead of a homogeneous distribution did not result in a better fit between observed and simulated sediment temperature profiles. The estimated groundwater fluxes however were greatly affected by using the measured thermal conductivities resulting in changes of ± 45% in estimated vertical fluxes.

Preliminary Results on Mineralogy and Geochemistry of Loki's Castle Arctic Vents and Host Sediments

NASA Astrophysics Data System (ADS)

Barriga, Fernando; Carvalho, Carlos; Inês Cruz, M.; Dias, Ágata; Fonseca, Rita; Relvas, Jorge; Pedersen, Rolf

2010-05-01

The Loki's Castle hydrothermal vent field was discovered in the summer of 2008, during a cruise led by the Centre of Geobiology of the University of Bergen, integrated in the H2Deep Project (Eurocores, ESF). Loki's Castle is the northernmost hydrothermal vent field discovered to date. It is located at the junction between the Mohns Ridge and the South Knipovich Ridge, in the Norwegian-Greenland Sea, at almost 74°N. This junction shows unique features and apparently there is no transform fault to accommodate the deformation generated by the bending of the rift valley from WSW-ENE to almost N-S. The Knipovich Rigde, being a complex structure, is an ultra-slow spreading ridge, with an effective spreading rate of only ~ 6 mm/y. It is partly masked by a substantial cover of glacial and post-glacial sediments, estimated to be between 12 and 20 ky old, derived from the nearby Bear Island fan, to the East of the ridge. The Loki's Castle vent site is composed of several active, over 10 m tall chimneys, producing up to 320°C fluid, at the top of a very large sulphide mound, which is estimated to be around 200 m in diameter. About a dozen gravity cores were obtained in the overall area. From these we collected nearly 200 subsamples. Eh and pH were measured in all subsamples. The Portuguese component of the H2Deep project is aimed at characterizing, chemically and mineralogically, the sulphide chimneys and the collected sediments around the vents (up to 5 meters long gravity cores). These studies are aimed at understanding the ore-forming system, and its implications for submarine mineral exploration, as well as the relation of the microbial population with the hydrothermal component of sediments. Here we present an overview of preliminary data on the mineralogical assemblage found in the analyzed sediments and chimneys. The identification of the different mineral phases was obtained through petrographic observations of polished thin sections under the microscope (with both transmitted and reflected light, for a clear identification of the ore paragenesis), X-Ray diffraction and electron microprobe analyses. The analyses were conducted in the geology labs of the University of Lisbon. The sulphide assemblage most commonly present in the samples consists of sphalerite (which seems also the most abundant), pyrite and pyrrhotite, with minor amounts of chalcopyrite. Sulphide-poor selected samples collected at the base of chimneys are mostly composed of halite, anhydrite, gypsum and talc. In sediment cores clays are largely predominant, mainly smectite and ilite, as well as chlorite. Combinations of quartz, calcite, anhydrite, gypsum and barite were also found in some of the samples.

Recent marine deposits reconstruction of two depositional environments of the French Atlantic coast

NASA Astrophysics Data System (ADS)

Pouzet, Pierre; Maanan, Mohamed; Schmidt, Sabine; Athimon, Emmanuelle; Robin, Marc

2017-04-01

This work provides a 300-yr high-resolution record of past storm and/or tsunami events using a multi-proxy analysis (137Cs and 210Pb dating, chemical composition and grain size) of sedimentary deposits from two coastal depositional environments of the French Atlantic coast. We analyse two wetland areas situated just behind a narrow coastal sand strip: 1) the Mer Blanche and 2) the Turballe. Evidence for strong extratropical storms and /or tsunamis events can be identified in this central part of the Bay of Biscay from the XIXth to the XXth century. Nine short sediment cores were collected in August 2016 using gravity type corer of 10 inner diameter and 100 cm length. Each core was longitudinally sliced, each half section photographed and described. High-resolution elemental analyses of split sediment cores were done using an Avaatech XRF core scanner. Then sediment cores were sampled every 0.5 cm. Grain size analysis was done using a Malvern 2600 laser beam grain sizer; organic carbon was measured by Leco induction furnace. 137Cs, 210Pb and 226Ra activities were measured on about 2 g dried sediment using a low background, well-type γ spectrometer (Canberra). The 210Pb in excess, which is used for dating, was calculated as the difference of measured 210Pb and of its supported activities (226Ra). The history information is performed using historical documents including narrative sources, ancient maps, records of cities repairs, surveys conducted after a disaster, newspaper from different departmental and national archives, and meteorological data. Coastal depositional environments were affected hardest by extreme environmental and climatological events during the last century. In the Mer Blanche core, three extreme episodes can be observed: i) at 36 cm, sediment is characterized by coarser sand and higher Sr/Al ratio, this episode coincides with a high tidal wave in spring 1937; ii) at 55 cm, we observe the presence of many gravels, they dates back to the high tidal wave of 1924 and iii) at 65 cm, the presence of another coarse pebble layer is attributed to a series of severe storms associated with coastal flooding episodes between 1910 and 1913. Acknowledgements The authors gratefully acknowledge Isabelle Billy (EPOC, University of Bordeaux 1) for XRF spectrometric core scanner analysis. This work was supported by grants from the Fondation de France through the research program « Quels littoraux pour demain? » and OR2C PDL regional framework.

K1-95-HW, cruise report 1995: preliminary results. Phase III: sediment chemistry and biological sampling survey

USGS Publications Warehouse

Torresan, M.E.; Hampton, M.A.; Barber, J.H.; Wong, F.L.

1995-01-01

Mamala Bay, off the south shore of the island of Oahu, has been used as a repository of dredged material primarily from Pearl and Honolulu Harbors for over a century. The U.S. Geological Survey, U.S. Army Corps of Engineers, and the U.S. Environmental Protection Agency are conducting an integrated study on the distribution and character of dredged materials as well as the effects of dredged material on the marine environment. A three phase study is providing information to evaluate the effects on seafloor substrate and the benthic fauna. The studies include geophysical profiling and imaging, bottom photography, sampling, chemical and physical analyses of sediment, and evaluations of the benthic population, population density, and adverse impacts to the benthic fauna. Phase 1, conducted in 1993, inventoried the seafloor via remote sensing. Sidescan sonar and subbottom profilers characterized the seafloor in and around the disposal sites, and the resulting products reveal the character and extent of the dredged material. These data were used to plan Phase 2 in 1994, a sampling program that employed subbottom profilers, video and still photography, and seafloor sampling to ground truth the sonar mosaic and identify the seafloor substrates responsible for the various acoustic signatures on the sonar images and subbottom profiles. Box coring provided the samples necessary to distinguish dredged material from native sediment, and for the chemical analyses used to determine contaminant concentrations. Phase 3 studies conducted in June of 1995 consisted of box core sampling for chemical and biological analyses. Specific studies include: infaunal taxonomy and population density, bioassay/bioaccumulation, sediment chemistry, and post-disposal resuspension and transport. The 1995 survey, conducted June 14 through 17, resulted in the collection of 39 box cores from 20 different stations. Multiple box cores were composited at 7 different locations occupied in 1994, to provide the material required for the 7 bioassay and bioaccumulation analyses currently underway (Figure 1). Seventeen of the 20 stations occupied provided the biological samples for the benthic infaunal identification and population density study conducted by Dr. Julie Brock of the University of Hawaii, and the sediment chemistry analyses conducted (and completed) by Quanterra Environmental Laboratories (Figure 1). Seven of the 20 stations occupied in 1995 were occupied in 1994, and provide the data for direct comparison of sediment chemistry at the same sites from two consecutive years. The sum total of the data collected from all three phases of the monitoring program will provide the U.S. Army Corps of Engineers and the U.S. Environmental Protection Agency with the information required to make informed decisions as to the management of the South Oahu disposal site in Mamala Bay.

Submarine paleoseismology of the northern Hikurangi subduction margin of New Zealand as deduced from Turbidite record since 16 ka

NASA Astrophysics Data System (ADS)

Pouderoux, Hugo; Proust, Jean-Noël; Lamarche, Geoffroy

2014-01-01

Paleoseismic studies seek to characterise the signature of pre-historical earthquakes by deriving quantitative information from the geological record such as the source, magnitude and recurrence of moderate to large earthquakes. In this study, we provide a ˜16,000 yr-long paleo-earthquake record of the 200 km-long northern Hikurangi Margin, New Zealand, using cm-thick deep-sea turbidites identified in sediment cores. Cores were collected in strategic locations across the margin within three distinct morphological re-entrants - the Poverty, Ruatoria and Matakaoa re-entrants. The turbidite facies vary from muddy to sandy with evidence for rare hyperpycnites interbedded with hemipelagites and tephra. We use the Oxal probabilistic software to model the age of each turbidite, using the sedimentation rate of hemipelagite deduced from well-dated tephra layers and radiocarbon ages measurements on planktonic foraminifera.

Spatial variability of metals in the inter-tidal sediments of the Medway Estuary, Kent, UK.

PubMed

Spencer, Kate L

2002-09-01

Concentrations of major and trace metals were determined in eight sediment cores collected from the inter-tidal zone of the Medway Estuary, Kent, UK. Metal associations and potential sources have been investigated using principal component analysis. These data provide the first detailed geochemical survey of recent sediments in the Medway Estuary. Metal concentrations in surface sediments lie in the mid to lower range for UK estuarine sediments indicating that the Medway receives low but appreciable contaminant inputs. Vertical metal distributions reveal variable redox zonation across the estuary and historically elevated anthropogenic inputs. Peak concentrations of Cu, Pb and Zn can be traced laterally across the estuary and their positions indicate periods of past erosion and/or non-deposition. However, low rates of sediment accumulation do not allow these sub surface maxima to be used as accurate geochemical marker horizons. The salt marshes and inter-tidal mud flats in the Medway Estuary are experiencing erosion, however the erosion of historically contaminated sediments is unlikely to re-release significant amounts of heavy metals to the estuarine system.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prahl, F.G.; Sparrow, M.A.; Eversmeyer, B.

Elemental and stable carbon isotopic compositions and biomarker concentrations were determined in sediments from the Columbia River basin and the Washington margin in order to evaluate geochemical approaches for quantifying terrestrial organic matter in marine sediments. The biomarkers include: an homologous series of long-chain n-alkanes derived from the surface waxes of higher plants; phenolic and hydroxyalkanoic compounds produced by CuO oxidation of two major vascular plant biopolymers, lignin and cutin. All marine sediments, including samples collected from the most remote sites in Cascadia Basin, showed organic geochemical evidence for the presence of terrestrial organic carbon. Using endmember values for themore » various biomarkers determined empirically by two independent means, the authors estimate that the terrestrial contribution to the Washington margin is [approximately] 60% for shelf sediments, [approximately] 30% for slope sediments, and decreases further to [le] 15% in basin sediments. Results from the same geochemical measurements made with depth in gravity core 6705-7 from Cascadia Seachannel suggest that this approach to assess terrestrial organic carbon contributions to contemporary deposits on the Washington margin can be applied to the study of sediments depositing in this region since the last glacial period.« less

Integration of the stratigraphic aspects of very large sea-floor databases using information processing

USGS Publications Warehouse

Jenkins, Clinton N.; Flocks, J.; Kulp, M.; ,

2006-01-01

Information-processing methods are described that integrate the stratigraphic aspects of large and diverse collections of sea-floor sample data. They efficiently convert common types of sea-floor data into database and GIS (geographical information system) tables, visual core logs, stratigraphic fence diagrams and sophisticated stratigraphic statistics. The input data are held in structured documents, essentially written core logs that are particularly efficient to create from raw input datasets. Techniques are described that permit efficient construction of regional databases consisting of hundreds of cores. The sedimentological observations in each core are located by their downhole depths (metres below sea floor - mbsf) and also by a verbal term that describes the sample 'situation' - a special fraction of the sediment or position in the core. The main processing creates a separate output event for each instance of top, bottom and situation, assigning top-base mbsf values from numeric or, where possible, from word-based relative locational information such as 'core catcher' in reference to sampler device, and recovery or penetration length. The processing outputs represent the sub-bottom as a sparse matrix of over 20 sediment properties of interest, such as grain size, porosity and colour. They can be plotted in a range of core-log programs including an in-built facility that better suits the requirements of sea-floor data. Finally, a suite of stratigraphic statistics are computed, including volumetric grades, overburdens, thicknesses and degrees of layering. ?? The Geological Society of London 2006.

Atmospheric mercury deposition during the last 270 years--A glacial ice core record of natural and anthropogenic sources

USGS Publications Warehouse

Schuster, Paul F.; Krabbenhoft, David P.; Naftz, David L.; Cecil, L. DeWayne; Olson, Mark L.; DeWild, John F.; Susong, David D.; Green, Jaromy R.; Abbott, Michael L.

2002-01-01

Mercury (Hg) contamination of aquatic ecosystems and subsequent methylmercury bioaccumulation are significant environmental problems of global extent. At regional to global scales, the primary mechanism of Hg contamination is atmospheric Hg transport. Thus, a better understanding of the long-term history of atmospheric Hg cycling and quantification of the sources is critical for assessing the regional and global impact of anthropogenic Hg emissions. Ice cores collected from the Upper Fremont Glacier (UFG), Wyoming, contain a high-resolution record of total atmospheric Hg deposition (ca. 1720−1993). Total Hg in 97 ice-core samples was determined with trace-metal clean handling methods and low-level analytical procedures to reconstruct the first and most comprehensive atmospheric Hg deposition record of its kind yet available from North America. The record indicates major atmospheric releases of both natural and anthropogenic Hg from regional and global sources. Integrated over the past 270-year ice-core history, anthropogenic inputs contributed 52%, volcanic events 6%, and background sources 42%. More significantly, during the last 100 years, anthropogenic sources contributed 70% of the total Hg input. Unlike the 2−7-fold increase observed from preindustrial times (before 1840) to the mid-1980s in sediment-core records, the UFG record indicates a 20-fold increase for the same period. The sediment-core records, however, are in agreement with the last 10 years of this ice-core record, indicating declines in atmospheric Hg deposition.

Lithologic, natural-gamma, grain-size, and well-construction data for Wright-Patterson Air Force Base, Ohio

USGS Publications Warehouse

Dumouchelle, D.H.; De Roche, Jeffrey T.

1991-01-01

Wright-Patterson Air Force Base, in southwestern Ohio, overlies a buried-valley aquifer. The U.S. Geological Survey installed 35 observation wells at 13 sites on the base from fall 1988 through spring 1990. Fourteen of the wells were completed in bedrock; the remaining wells were completed in unconsolidated sediments. Split-spoon and bedrock cores were collected from all of the bedrock wells. Shelby-tube samples were collected from four wells. The wells were drilled by either the cable-tool or rotary method. Data presented in this report include lithologic and natural-gamma logs, and, for selected sediment samples, grain-size distributions of permeability. Final well-construction details, such as the total depth of well, screened interval, and grouting details, also are presented.

Geochemical record of methane seepage in authigenic carbonates and surrounding host sediments: A case study from the South China Sea

NASA Astrophysics Data System (ADS)

Hu, Yu; Chen, Linying; Feng, Dong; Liang, Qianyong; Xia, Zhen; Chen, Duofu

2017-05-01

Sediments at marine methane seep sites provide potential archives of past fluid flow that serve to explore seepage activities over time. Three gravity cores (D-8, D-F, and D-7) were collected from seep sites on the northern slope of the South China Sea where gas hydrates were drilled in the subsurface. Various carbon and sulfur contents, δ13C values of total inorganic carbon (δ13CTIC), δ34S values of chromium reducible sulfur (δ34SCRS), trace element contents, grain size, and AMS 14C dating of planktonic Foraminifera in the sediments were determined to explore the availability of related proxies at seeps and to trace past methane seepage activities. Evidence for the presence of methane seepage and consequently anaerobic oxidation of methane comes from the occurrence of 13C-depleted authigenic carbonate nodules (δ13C values as low as -49‰) discovered at an interval of 150-200 cm in core D-7. This finding is supported by high S/C ratios and molybdenum enrichment in the same interval. However, low contents of CRS and negative δ34SCRS values are present. It is suggested to reflect a transient methane seepage event, which continued for about 1 ka based on the 14C ages. Cores D-8 and D-F have δ13CTIC values close to zero, low S/C ratios and CRS contents, negative δ34SCRS values, and no trace element enrichment, suggesting a negligible impact of methane-seepage on the sediments. The negative δ34SCRS values of the studied seep-impacted and background sediments suggest that the application of δ34SCRS alone as a proxy to identify AOM-related process may be insufficient. Sediment carbon-sulfur-trace element systematics and 14C ages used here have the potential to be a promising tool to recognize transient methane seepages and constrain their timescales.

Anthropogenic tritium in the Loire River estuary, France

NASA Astrophysics Data System (ADS)

Péron, O.; Gégout, C.; Reeves, B.; Rousseau, G.; Montavon, G.; Landesman, C.

2016-12-01

This work is carried out in the frame of a radioecological monitoring of anthropogenic tritium from upstream and downstream of several nuclear power plants along the Loire River to its estuary. This paper studies the variation of anthropogenic tritium species in the Loire River system from upstream to the mouth of the estuary. Tritiated water (HTO and HTO in sediment pore water) and organically bound tritium (OBT) forms were analysed after dedicated pre-treatments. The collected environmental samples consist in (i) surface-sediment and core samples from the river floor, (ii) surface and water column samples. A maximum 3H activity concentration of 26 ± 3 Bq·L- 1 in the Loire River estuary is obtained whereas an environmental background level around 1 Bq·L- 1 is determined for a non influenced continental area by anthropogenic activities. The European follow-up indicator used as a screening value is 100 Bq·L- 1. The conservative tritium behaviour was used in order to characterize the tidal regime and river flow influences in the mixing zone of the Loire River estuary. Furthermore, OBT levels and total organically carbon (TOC) content are explored. Finally, ratios of OBT relative to HTO in sediment pore water in surface-sediment and core samples are also discussed.