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Sample records for lake sediments asylum

  1. Mercury dynamics in lake sediments

    NASA Astrophysics Data System (ADS)

    Feyte, Stéphane; Gobeil, Charles; Tessier, André; Cossa, Daniel

    2012-04-01

    Triplicate porewater depth-profiles of pH and concentrations of total Hg (HgT), methylmercury (MeHg), Fe, Mn, sulfate, total sulfide, total zero-valent sulfur, organic C and major ions were determined at two sampling dates in a perennially oxygenated basin and a seasonally anoxic basin from Lake Tantaré, a Canadian Shield lake. The vertical distribution of HgT, MeHg, acid volatile sulfide, total S, Fe, Mn, Al and organic C were also determined in dated sediment cores from the same lake basins and from the deepest site of two other lakes, one also located in the Canadian Shield and the other in the Northeastern part of the Appalachian Mountains. Application of a one-dimensional transport-reaction equation to the dissolved HgT and MeHg profiles constrains the depth intervals (zones) where these species are produced or consumed in the sedimentary column and yields estimates of net reaction rates of HgT or MeHg in each of the zones as well as their fluxes at the sediment-water interface. Dissolved HgT and MeHg diffused from the overlying water into the sediments, except for MeHg at one of the sampling dates in the perennially oxygenated basin. About 97% and 50% of the MeHg flux to the sediments is presently deposited with settling particles in the perennially oxygenated and seasonally anoxic basins, respectively. Removal of porewater HgT and MeHg occurred at all dates and sampling sites. Comparison of the consumption zones of porewater HgT and MeHg with the profiles of ancillary parameters, coupled with thermodynamic calculations, suggest that pure Hg mineral phases do not form in the sediments, that HgT and MeHg adsorption onto authigenic Fe oxyhydroxides occurs in minor proportions, and that the association of HgT and MeHg to Fe sulfide phases or sulfidized organic matter is possible. Assuming that the net consumption of MeHg in the porewaters was essentially due to demethylation, an apparent first-order rate constant for MeHg demethylation of 0.04-0.8 d-1 was

  2. Mercury distribution in sediment profiles of six Louisiana Lakes.

    PubMed

    Gambrell, R P; DeLaune, R D; Patrick, W H; Jugsujinda, A

    2001-05-01

    A study was conducted of six Louisiana Lakes to examine the relationship between sediment properties including mercury content and health advisories associated with mercury levels in fish. Comparison was made between three lakes with health advisories (Black Lake, Chicot Lake, and Henderson Lake) and three lakes where the levels of mercury in fish are below health advisory levels (False River, Lake St. John, and Miller Lake). Three sediment core samples were collected from each lake and sectioned into 2-cm increments to a depth of 20 cm. Sediment properties measured in each depth increment of the sediment profile included total mercury, 137Cs activity (for sedimentation rate), and sediment organic matter content. Of the lakes studied, those lakes that have health advisories for mercury tended to have higher total mercury contents, usually higher sediment organic matter contents, and higher sedimentation rates than sediments in lakes where health advisories for mercury are not issued.

  3. Hydraulic potential in Lake Michigan bottom sediments

    USGS Publications Warehouse

    Cartwright, K.; Hunt, C.S.; Hughes, G.M.; Brower, R.D.

    1979-01-01

    The magnitude and direction of groundwater flux in the bottom sediments of Lake Michigan were deduced from measurements made during three shipboard cruises between 1973 and 1975. These factors affect the geochemical environment of the sediments and therefore the distribution of trace elements reported to be present. The near-shore, sandy-bottom and fine-grained, soft, deep-lake sediments were investigated; areas of hard till or bedrock were not included in the study. Thirty-three piezometers were placed in near-shore sands in waters 5-15 m deep. The piezometers were placed an average of 3 m into the bottom sediment. Water levels from the piezometers averaged 0.6 cm above the lake level, equivalent to an upward hydraulic gradient of about 0.002 cm/cm. Water samples taken from the piezometers have a distinctly different chemical composition from that of the lake water. The total dissolved mineral content and hardness of the groundwater are about twice those of the lake water. Twenty-two hydraulic gradient measurements were made in the fine-grained soft deep-lake sediments in waters 48-140 m deep by using a differential-pressure transducer dropped into the sediments. These measurements show an upward gradient averaging 0.2 cm/cm. No chemical data were obtained for the groundwater in the deep-lake sediments. The results of this study indicate that the groundwater flux is upward through the bottom sediments into Lake Michigan and that there is a chemical change in the water near the water-sediment contact. ?? 1979.

  4. Classification of lake sediments using a hydrocyclone.

    PubMed

    Park, J H; Jo, Y M; Oh, J M

    2003-01-01

    The present work is a preliminary experiment for hydrocyclones as a primary process in lake sediment thickening. A few cyclones based on the Rietema standard geometry were prepared, and sample particles were sediments from a local lake and waste coal fly ash for a reference test. As a result of the chemical analysis, more organic contaminants were found in smaller particles. The experimental tests showed that physical characteristics of particles, configuration of the cyclone and operation conditions could affect the separation efficiency.

  5. Fine-Sediment Loadings to Lake Tahoe

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Over the past 35 years, a trend of decreasing water clarity has been documented in Lake Tahoe, attributable in part to the delivery of fine-grained sediments emanating from upland and channel sources. The overall objective of the research reported here was to determine the amount of fine sediment de...

  6. Anthropopression markers in lake bottom sediments

    NASA Astrophysics Data System (ADS)

    Nadolna, Anna; Nowicka, Barbara

    2014-05-01

    Lakes are vulnerable to various types of anthropogenic disturbances. Responses of lake ecosystems to environmental stressors are varied and depend not only on the type of a factor but also on the lake natural resistance to degradation. Within the EULAKES project an evaluation of anthropogenic stress extent in a flow-through, postglacial, ribbon lake (Lake Charzykowskie) was carried out. It was assumed, that this impact manifests unevenly, depending on a type and degree of the pressure on the shore zones, water quality of tributaries, lake basin shape and dynamics of a water movement. It was stated, that anthropogenic markers are substances accumulated in bottom sediments as a result of allochthonous substances inflow from the catchment and atmosphere. Along the selected transects 105 samples from the top layer of sediments (about 20 cm) was collected representing the contemporary accumulation (about 15 years). The content of selected chemical elements and compounds was examined, including nutrients (TN and TP), heavy metals (arsenic, cadmium, lead, chromium, nickel, copper, zinc, mercury, iron, and manganese) and pesticides (DDT, DDD, DDE, DMDT , γ-HCH). The research was conducted in the deepest points of each lake basin and along the research transects - while choosing the spots, the increased intensity of anthropogenic impact (ports, roads with heavy traffic, wastewater discharge zones, built-up areas) was taken into consideration. The river outlets to the lake, where there are ecotonal zones between limnic and fluvial environment, were also taken into account. Analysis of the markers distribution was carried out against the diversity of chemical characteristics of limnic sediments. Ribbon shape of the lake basin and the dominant wind direction provide an opportunity of easy water mixing to a considerable depth. Intensive waving processes cause removal of the matter from the littoral zone towards lake hollows (separated by the underwater tresholds), where the

  7. Importance of elemental mercury in lake sediments.

    PubMed

    Bouffard, Ariane; Amyot, Marc

    2009-02-01

    Mercury (Hg) redox changes in sediments are poorly studied and understood, even though they potentially control Hg availability for methylation and can alter sediment-water Hg exchange. Elemental Hg (Hg(0)) concentrations in sediments of two Canadian Shield lakes were assessed by thermodesorption. Hg(0) concentrations in sediments varied between 6.3 and 60.3 pg g(-1) (wet weight) which represented 7.4-28.4% of total mercury (HgT) concentration. Hg(0) concentrations were similar in both lakes. Hg(0) was rapidly adsorbed on sediments in controlled adsorption experiments and surface sediments sampled in summer had a stronger affinity for Hg(0) than deeper sediments and sediments sampled in fall. This adsorption was positively correlated to organic matter content and negatively related to particle grain size, pH and oxygen concentration in overlying water. This study demonstrates that Hg(0) is a prevalent species in sediments, but not in porewater, because of the high sorptive capacity of sediments towards Hg(0). Its potential availability towards Hg methylating bacteria remains to be determined.

  8. Archaea in Arctic Thermokarst Lake Sediments

    NASA Astrophysics Data System (ADS)

    Matheus Carnevali, P. B.; Rohrssen, M.; Dodsworth, J. A.; Kuhn, E.; Williams, M.; Adams, H. E.; Berisford, D. F.; Hand, K. P.; Priscu, J. C.; Walter Anthony, K.; Love, G. D.; Hedlund, B. P.; Murray, A. E.

    2011-12-01

    Thermokarst lakes in the Northern Slope of Alaska are known to emit ebullient methane (CH4), some of which is of biogenic origin. Thawing of permafrost in the margins and bottom of these lakes, as a result of climate change, releases sources of carbon that could be used by methanogenic Archaea. However, the composition of Archaea inhabiting these lakes is not known. We have chosen a subset of Thermokarst lakes near Barrow Alaska to determine if there are methanogenic and methane oxidizing Archaea in these lake sediments. To describe the diversity of the archaeal community in the sediments we profiled the variable 3 (v3) region of the 16S rRNA gene of Archaea. The v3 profiles indicated surprisingly high levels of diversity, with 20 to 36 bands in the 10 sample horizons over the upper 100 cm of sediments surveyed in four lakes, at two times of the year. One of v3 rRNA gene bands was common to all lakes, and most phylotypes were grouped by depth (1-40 cm or 41-105 cm) within a lake. Likewise, cluster analysis indicated partitioning of archaeal communities between lakes. To specifically detect methanogens and anaerobic methanotrophs (ANME) in the sediments, DNA was surveyed by PCR to detect the methyl coenzyme M reductase (mcrA) gene, which is specific to the pathways of methanogenesis and anaerobic methane oxidation (AMO). An array of methanogen enrichment cultures was also set up. The expected 464-491 bp amplification product predicted for the mcrA gene was detected in all sediment samples. Assays of enrichment cultures incubated at 2 and 10 °C with substrates used in the main pathways for methanogenesis have produced positive growth and CH4 production results. Most cultures produced CH4 from carbon dioxide (CO2) reduction with hydrogen (H2), although methanol and acetate were also utilized as methanogenic substrates by a few cultures. From the experiments conducted to date we conclude that there is a great diversity of Archaea inhabiting these Thermokarst lakes

  9. Detecting Magnetosomes in Freshwater Lakes and Lake Sediments

    NASA Astrophysics Data System (ADS)

    Kodama, K. P.; Kim, B.; Kopp, B.; Chen, A. P.

    2008-05-01

    We will present a summary of the work done to date on detecting magnetosomes in the lake sediments and water column of Lake Ely, a small post-glacial lake in northeastern Pennsylvania. To establish that magnetosomes dominate the magnetic mineralogy of the Lake Ely sediments we sampled the water column every meter down to its maximum depth of 23 m and measured the dissolved oxygen, sulfide, and iron, as well as the ARM of the material filtered from the water. We examined the water samples for magnetotactic bacteria. These results established an increase in the ARM of the filtered material at the oxic-anoxic transition. They also showed that the ARM was carried by magnetosomes produced by magnetotactic bacteria living in the water column at depths from 15-19 m. TEM of magnetic separates collected from the lake sediments show that magnetosomes are transferred to the sediments from the water column and are a significant fraction of the magnetic minerals in the sediments. We used a variety of mineral magnetic techniques to magnetically characterize the magnetosomes in the lake sediments. The delta-delta ratio test of low temperature behavior at the Verwey transition (Moskowitz et al., 1993) gave values of 1.2 to 1.5, lower than the theoretically predicted level of 2 for magnetosomes, but a numeric unmixing technique could resolve higher delta-delta ratios in the dark organic-rich layers in the sediments where magnetosomes were more prevalent. ARM/SIRM ratios of 0.15 to 0.35 with Raf values (the crossover of an IRM acquisition curve versus its alternating field demagnetization curve) of 0.45 to 0.5 are consistent with the presence of magnetosomes in the sediments, the water column, and in a sediment trap located at the bottom of the lake. IRM and ARM acquisition modeling of samples collected from a 160 cm piston core revealed two components of magnetization with coercivities of about 25 mT and 65 mT that are identified as Egli's (2004) biogenic soft (BS) and biogenic

  10. Ancient plant DNA in lake sediments.

    PubMed

    Parducci, Laura; Bennett, Keith D; Ficetola, Gentile Francesco; Alsos, Inger Greve; Suyama, Yoshihisa; Wood, Jamie R; Pedersen, Mikkel Winther

    2017-04-03

    Contents I. II. III. IV. V. VI. VII. VIII. IX. X. XI. References SUMMARY: Recent advances in sequencing technologies now permit the analyses of plant DNA from fossil samples (ancient plant DNA, plant aDNA), and thus enable the molecular reconstruction of palaeofloras. Hitherto, ancient frozen soils have proved excellent in preserving DNA molecules, and have thus been the most commonly used source of plant aDNA. However, DNA from soil mainly represents taxa growing a few metres from the sampling point. Lakes have larger catchment areas and recent studies have suggested that plant aDNA from lake sediments is a more powerful tool for palaeofloristic reconstruction. Furthermore, lakes can be found globally in nearly all environments, and are therefore not limited to perennially frozen areas. Here, we review the latest approaches and methods for the study of plant aDNA from lake sediments and discuss the progress made up to the present. We argue that aDNA analyses add new and additional perspectives for the study of ancient plant populations and, in time, will provide higher taxonomic resolution and more precise estimation of abundance. Despite this, key questions and challenges remain for such plant aDNA studies. Finally, we provide guidelines on technical issues, including lake selection, and we suggest directions for future research on plant aDNA studies in lake sediments.

  11. Sedimentation profiles in Lake Tuscaloosa, Alabama, 2000

    USGS Publications Warehouse

    Stricklin, Victor E.

    2001-01-01

    Lake Tuscaloosa, created in 1969 by the impoundment of North River, is the primary water supply for the cities of Tuscaloosa and Northport, Alabama, and surrounding areas. In 1982, 17 cross-sections were established in the principal tributaries of the lake, which include North River, Dry Creek, Turkey Creek, Binion Creek, Tierce Creek, Carroll Creek, and Brush Creek. These cross-sections were resurveyed in 1986 to determine the amount of sedimentation or scour occurring in the lake at these areas. In May 2000, 14 of the 17 cross-sections were located for resurveying to determine the amount of sedimentation or scour since 1986. The maximum amount of sediment deposition determined from the 2000 survey occurred in the upper end of the Carroll Creek tributary at cross-section CC8 (3.0 feet). The maximum amount of scour occurred in the Turkey Creek tributary at cross-section TRC2 (7.0 feet). Of the 14 cross-sections, 6 indicated increased amounts of sediment deposition, 5 indicated scouring of bottom sediments, and 3 indicated little or no change.

  12. Big lake records preserved in a little lake's sediment: An example from Silver Lake, Michigan, USA

    USGS Publications Warehouse

    Fisher, T.G.; Loope, W.L.; Pierce, W.; Jol, H.M.

    2007-01-01

    We reconstruct postglacial lake-level history within the Lake Michigan basin using soil stratigraphy, ground-penetrating radar (GPR), sedimentology and 14C data from the Silver Lake basin, which lies adjacent to Lake Michigan. Stratigraphy in nine vibracores recovered from the floor of Silver Lake appears to reflect fluctuation of water levels in the Lake Michigan basin. Aeolian activity within the study area from 3,000 years (cal yr. B.P.) to the present was inferred from analysis of buried soils, an aerial photograph sequence, and GPR. Sediments in and around Silver Lake appear to contain a paleoenvironmental record that spans the entire post-glacial history of the Lake Michigan basin. We suggest that (1) a pre-Nipissing rather than a Nipissing barrier separated Silver Lake basin from the Lake Michigan basin, (2) that the Nipissing transgression elevated the water table in the Silver Lake basin about 6,500 cal yr. B.P., resulting in reestablishment of a lake within the basin, and (3) that recent dune migration into Silver Lake is associated with levels of Lake Michigan.

  13. Preliminary cross section of Englebright Lake sediments

    USGS Publications Warehouse

    Snyder, Noah P.; Hampton, Margaret A.

    2003-01-01

    Overview -- The Upper Yuba River Studies Program is a CALFED-funded, multidisciplinary investigation of the feasibility of introducing anadromous fish species to the Yuba River system upstream of Englebright Dam. Englebright Lake (Figure 1 on poster) is a narrow, 14-km-long reservoir located in the northern Sierra Nevada, northeast of Marysville, CA. The dam was completed in 1941 for the primary purpose of trapping sediment derived from mining operations in the Yuba River watershed. Possible management scenarios include lowering or removing Englebright Dam, which could cause the release of stored sediments and associated contaminants, such as mercury used extensively in 19th-century hydraulic gold mining. Transport of released sediment to downstream areas could increase existing problems including flooding and mercury bioaccumulation in sport fish. To characterize the extent, grain size, and chemistry of this sediment, a coring campaign was done in Englebright Lake in May and June 2002. More than twenty holes were drilled at 7 different locations along the longitudinal axis of the reservoir (Figure 4 on poster), recovering 6 complete sequences of post-reservoir deposition and progradation. Here, a longitudinal cross section of Englebright Lake is presented (Figure 5 on poster), including pre-dam and present-day topographic profiles, and sedimentologic sections for each coring site. This figure shows the deltaic form of the reservoir deposit, with a thick upper section consisting of sand and gravel overlying silt, a steep front, and a thinner lower section dominated by silt. The methodologies used to create the reservoir cross section are discussed in the lower part of this poster.

  14. Chemical composition of surficial sediment in Geneva Lake, Wisconsin

    USGS Publications Warehouse

    Elder, John F.; Robertson, Dale M.; Garrison, Paul J.

    2000-01-01

    Intense recreational use of Geneva Lake and extensive residential and other development in its watershed (fig. 1) has created concern over a possible decline in water quality of the lake. Because of this concern, a collaborative effort between the U.S. Geological Survey (USGS), Wiscon- sin Department of Natural Resources (WDNR), and the Geneva Lake Environmental Agency was begun to document the present quality of the water and its sediments, to estimate the amount of nutrients (primarily phosphorus) coming into the lake, and to describe changes that have occurred in the lake over the past 200 years. In this fact sheet, we describe the quality of the surficial sediments of the lake.

  15. [Limnology of high mountain tropical lake, in Ecuador: characteristics of sediments and rate of sedimentation].

    PubMed

    Gunkel, Günter

    2003-06-01

    Equatorial high mountain lakes are a special type of lake occurring mainly in the South American Andes as well as in Central Africa and Asia. They occur at altitudes of a few thousand meters above sea level and are cold-water lakes (< 20 degrees C). Relatively little is known about them. A long-term limnological study was therefore undertaken at Lake San Pablo, Ecuador, to analyze the basic limnological processes of the lake, which has a tendency for eutrophication. Sediment quality of San Pablo Lake is given under consideration of horizontal and vertical distribution using sediment cores. Significance of sediments for eutrophication process of lakes is demonstrated using phosphorus concentration of sediments as well as the phosphorus retention capacity of the sediments by ratio Fe/P. Dating of the sediments is done using 137Cs and 210Pb, but the activity of 137Cs in the sediment was very low nearly at the detection level. Sedimentation rate is determined to be 3.5 mm/year and the sediment cores represent about 110 years. P concentration of the sediments is high (approximately 5 g/kg dry substance), and P retention capacity by Fe is insufficient (Fe/P = 4). The sediment quality did not change significantly during the past decades, and the trophic state of San Pablo Lake was already less or more eutrophic 110 years ago. The contamination of the lake sediments by heavy metals is insignificant.

  16. Sediment characteristics and sedimentation rates in Lake Michie, Durham County, North Carolina, 1990-92

    USGS Publications Warehouse

    Weaver, J.C.

    1994-01-01

    A reservoir sedimentation study was conducted at 508-acre Lake Michie, a municipal water-supply reservoir in northeastern Durham County, North Carolina, during 1990-92. The effects of sedimentation in Lake Michie were investigated, and current and historical rates of sedimentation were evaluated. Particle-size distributions of lake-bottom sediment indicate that, overall, Lake Michie is rich in silt and clay. Nearly all sand is deposited in the upstream region of the lake, and its percentage in the sediment decreases to less than 2 percent in the lower half of the lake. The average specific weight of lake-bottom sediment in Lake Michie is 73.6 pounds per cubic foot. The dry-weight percentage of total organic carbon in lake-bottom sediment ranges from 1.1 to 3.8 percent. Corresponding carbon-nitrogen ratios range form 8.6 to 17.6. Correlation of the total organic carbon percentages with carbon-nitrogen ratios indicates that plant and leaf debris are the primary sources of organic material in Lake Michie. Sedimentation rates were computed using comparisons of bathymetric volumes. Comparing the current and previous bathymetric volumes, the net amount of sediment deposited (trapped) in Lake Michie during 1926-92 is estimated to be about 2,541 acre-feet or slightly more than 20 percent of the original storage volume computed in 1935. Currently (1992), the average sedimentation rate is 38 acre-feet per year, down from 45.1 acre-feet per year in 1935. To confirm the evidence that sedimentation rates have decreased at Lake Michie since its construction in 1926, sediment accretion rates were computed using radionuclide profiles of lake-bottom sediment. Sediment accretion rates estimated from radiochemical analyses of Cesium-137 and lead-210 and radionuclides in the lake-bottom sediment indicate that rates were higher in the lake?s early years prior to 1962. Estimated suspended-sediment yields for inflow and outflow sites during 1983-91 indicate a suspended-sediment trap

  17. Microplastic pollution in lakes and lake shoreline sediments - A case study on Lake Bolsena and Lake Chiusi (central Italy).

    PubMed

    Fischer, Elke Kerstin; Paglialonga, Lisa; Czech, Elisa; Tamminga, Matthias

    2016-06-01

    Rivers and effluents have been identified as major pathways for microplastics of terrestrial sources. Moreover, lakes of different dimensions and even in remote locations contain microplastics in striking abundances. This study investigates concentrations of microplastic particles at two lakes in central Italy (Lake Bolsena, Lake Chiusi). A total number of six Manta Trawls have been carried out, two of them one day after heavy winds occurred on Lake Bolsena showing effects on particle distribution of fragments and fibers of varying size categories. Additionally, 36 sediment samples from lakeshores were analyzed for microplastic content. In the surface waters 2.68 to 3.36 particles/m(3) (Lake Chiusi) and 0.82 to 4.42 particles/m(3) (Lake Bolsena) were detected, respectively. Main differences between the lakes are attributed to lake characteristics such as surface and catchment area, depth and the presence of local wind patterns and tide range at Lake Bolsena. An event of heavy winds and moderate rainfall prior to one sampling led to an increase of concentrations at Lake Bolsena which is most probable related to lateral land-based and sewage effluent inputs. The abundances of microplastic particles in sediments vary from mean values of 112 (Lake Bolsena) to 234 particles/kg dry weight (Lake Chiusi). Lake Chiusi results reveal elevated fiber concentrations compared to those of Lake Bolsena what might be a result of higher organic content and a shift in grain size distribution towards the silt and clay fraction at the shallow and highly eutrophic Lake Chiusi. The distribution of particles along different beach levels revealed no significant differences.

  18. MERCURY IN SEDIMENT AND FISH FROM NORTH MISSISSIPPI LAKES.

    EPA Science Inventory

    Sediments and/or fish were collected from Sardis, Enid and Grenada Lakes, which are located in three different watersheds in North Mississippi, in order to assess mercury contamination. The mean total mercury concentration in sediments from Enid Lake in 1997 was 0.154 mg Hg/kg, w...

  19. TOXAPHENE STUDY OF GREAT LAKES TRIBUTARY SEDIMENTS

    EPA Science Inventory

    The Product is the paper "Pulp and Paper Mills as Sources of Toxaphene to Lake Superior and Northern Lake Michigan" published in the Journal of Great Lakes Research, 25(2):383-394 International Association of Great Lakes 1999.

  20. 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.

  1. Sediment accumulation and distribution in Lake Kampeska, Watertown, South Dakota

    USGS Publications Warehouse

    Schaap, Bryan D.; Sando, Steven K.

    2002-01-01

    Lake Kampeska is a natural lake of about 5,075 acres located within the city limits of Watertown, South Dakota. The lake is important as a water supply and recreational resource. Sediment accumulation has been a concern for many years, and several studies have been conducted to learn more about the sediment, including how fast it is accumulating. This study attempted to evaluate previously estimated sediment-accumulation rates and to describe the distribution of sediment in the lake. Analysis of cesium-137 concentrations in sediment cores and changes in lake-bottom elevation over time led to the conclusion that during about the last 50 years, the sediment has been accumulating at a rate on the order of 0.01 foot per year or less. Changes in lake-bottom elevation during this time period indicate that the only significant deposition occurred in the area near the connection of Lake Kampeska to the Big Sioux River. Direct physical measurements and marine seismic surveys indicate that the flat-bottom interior part of the lake has 10 feet or more of sediment over a relatively irregular subbottom.

  2. Varves in lake sediments - a review

    NASA Astrophysics Data System (ADS)

    Zolitschka, Bernd; Francus, Pierre; Ojala, Antti E. K.; Schimmelmann, Arndt

    2015-06-01

    Downcore counting of laminations in varved sediments offers a direct and incremental dating technique for high-resolution climatic and environmental archives with at least annual and sometimes even seasonal resolution. The pioneering definition of varves by De Geer (1912) had been restricted to rhythmically deposited proglacial clays. One century later the meaning of 'varve' has been expanded to include all annually deposited laminae in terrestrial and marine settings. Under favourable basin configurations and environmental conditions, limnic varves are formed due to seasonality of depositional processes from the lake's water column and/or transport from the catchment area. Subsequent to deposition of topmost laminae, the physical preservation of the accumulating varved sequence requires the sustained absence of sediment mixing, for example via wave action or macrobenthic bioturbation. Individual (sub)laminae in varved lake sediments typically express contrasting colours, always differ in terms of their organic, chemical and/or mineralogical compositions, and often also differ with regard to grain-size. Various predominating climatic and depositional conditions may result in clastic, biogenic or endogenic (incl. evaporitic) varved sediments and their mixtures. To reliably establish a varve chronology, the annual character of laminations needs to be determined and verified in a multidisciplinary fashion. Sources and influences of possible errors in varve chronologies are best determined and constrained by repeated varve counts, and by including radioisotopes and correlation with historically documented events. A well-established varve chronology greatly enhances the scientific value of laminated limnic archives by securely anchoring the wealth of multi-proxy palaeoenvironmental information in the form of time-series for multidisciplinary investigations. Applications of varved records are discussed with special reference to advances since the 1980s. These span fields

  3. Sedimentation of Lake Taneycomo, Missouri, 1913-1987

    USGS Publications Warehouse

    Berkas, W.R.

    1989-01-01

    On the basis of the data from a sedimentation survey done by the U.S. Department of Agriculture, Soil Conservation Service, during 1935 and data collected by the U.S. Geological Survey during 1987, the volume of sediment accumulated in Lake Taneycomo from 1913 to 1935 and 1913 to 1987 was determined. Table Rock Dam, built directly upstream from Lake Taneycomo during 1958, eliminated about 92% of the 4,644-sq mi basin from contributing sediment directly to the lake. Cesium-137 isotope was used as a tracer in the sediment to determine the quantity of deposition in the lake after Table Rock Dam was completed. The relation between cross-sectional area and distance upstream from the dam (curve method) was used to determine the 1913 (original), the 1935, and the 1987 volumes of Lake Taneycomo. A total of 910,000,000 cu ft of sediment accumulated between 1913 and 1935, 42% of the original volume of the lake. A total of 1 ,066,000,000 cu ft of sediment accumulated between 1913 and 1987 , 49% of the original volume. Lake Taneycomo seems to be functioning as an alluvial river, responding to the new energy gradient established by the spillway at Ozark Beach Dam, and later to changes in the sediment load. The upper two-thirds of the lake seems to have been scoured after Table Rock Dam greatly decreased the sediment load to the lake. The cesium-137 analysis indicated that sediment is still accumulating in the lower reaches of the lake, with measured accumulation generally ranging from 0.2 to 2.6 ft. (USGS)

  4. Dark Carbon Fixation: An Important Process in Lake Sediments

    PubMed Central

    Santoro, Ana Lúcia; Bastviken, David; Gudasz, Cristian; Tranvik, Lars; Enrich-Prast, Alex

    2013-01-01

    Close to redox boundaries, dark carbon fixation by chemoautotrophic bacteria may be a large contributor to overall carbon fixation. Still, little is known about the relative importance of this process in lake systems, in spite the potentially high chemoautotrophic potential of lake sediments. We compared rates of dark carbon fixation, bacterial production and oxygen consumption in sediments from four Swedish boreal and seven tropical Brazilian lakes. Rates were highly variable and dark carbon fixation amounted up to 80% of the total heterotrophic bacterial production. The results indicate that non-photosynthetic carbon fixation can represent a substantial contribution to bacterial biomass production, especially in sediments with low organic matter content. PMID:23776549

  5. Sedimentation in Santa Margarita Lake, San Luis Obispo County, California

    USGS Publications Warehouse

    Glysson, G. Douglas

    1977-01-01

    The 1975 storage capacity of Santa Margarita Lake in San Luis Obispo County, Calif., was 41,400 acre-feet, a decrease of 3,400 acre-feet since 1941. Usable capacity decreased from 25,800 to 23,000 acre-feet. Long-term sediment yield for the Salinas River basin upstream from the lake was estimated at 1,150 tons per square mile per year. A correlation between the annual water discharge of the Salinas River near Pozo and the annual quantity of sediment deposited in the lake was developed that can be used to stimate future sediment deposition. (Woodard-USGS)

  6. Organophosphate Esters in Sediment of the Great Lakes.

    PubMed

    Cao, Dandan; Guo, Jiehong; Wang, Yawei; Li, Zhuona; Liang, Kang; Corcoran, Margaret B; Hosseini, Soheil; Bonina, Solidea M C; Rockne, Karl J; Sturchio, Neil C; Giesy, John P; Liu, Jingfu; Li, An; Jiang, Guibin

    2017-02-07

    This is the first study on organophosphate ester (OPEs) flame retardants and plasticizers in the sediment of the Great Lakes. Concentrations of 14 OPEs were measured in three sediment cores and 88 Ponar surface grabs collected from Lakes Ontario, Michigan, and Superior of North America. The sum of these OPEs (Σ14OPEs) in Ponar grabs averaged 2.2, 4.7, and 16.6 ng g(-1) dw in Lakes Superior, Michigan, and Ontario, respectively. Multiple linear regression analyses demonstrated statistically significant associations between logarithm concentrations of Σ14OPEs as well as selected congeners in surface grab samples and sediment organic carbon content as well as a newly developed urban distance factor. Temporal trends observed in dated sediment cores from Lake Michigan demonstrated that the recent increase in depositional flux to sediment is dominated by chlorinated OPEs, particularly tris(2-chloroisopropyl) phosphate (TCPP), which has a doubling time of about 20 years. Downward diffusion within sediment may have caused vertical fractionation of OPEs over time. Two relatively hydrophilic OPEs including TCPP had much higher concentrations in sediment than estimated based on equilibria between water and sediment organic carbon. Approximately a quarter (17 tonnes) of the estimated total OPE burden (63 tonnes) in Lake Michigan resides in sediment, which may act as a secondary source releasing OPEs to the water column for years to come.

  7. Holocene and recent sediment accumulation rates in southern Lake Michigan

    USGS Publications Warehouse

    Colman, Steven M.; King, J.W.; Jones, Glenn A.; Reynolds, R.L.; Bothner, Michael H.

    2000-01-01

    Rates of sediment accumulation in Lake Michigan are a key component of its geologic history and provide important data related to societal concerns such as shoreline erosion and the fate of anthropogenic pollutants. Previous attempts to reconstruct Holocene rates of sediment accumulation in Lake Michigan, as well as in the other Laurentian Great Lakes, have been bedeviled by the effect of refractory terrestrial material on radiocarbon ages from total organic carbon samples of lake sediments. AMS radiocarbon ages on small samples of biogenic carbonate (ostracodes and mollusks) in Lake Michigan provide accurate Holocene ages. The present bicarbonate reservoir effect is estimated from shells of mollusks collected live before atmospheric nuclear testing to be 250 yr. From paired samples of biogenic carbonate and terrestrial macrofossils, the past reservoir effect is thought to be less than 500 yr. The radiocarbon ages indicate a distinct decrease in sediment accumulation rates throughout the southern basin of Lake Michigan at about 5 ka, about the time when lake level stabilized at the Nipissing level after rising rapidly for several thousand years. Average rates of sediment accumulation for the historic period (the last 150 yr) can be estimated from radioisotopes (210Pb and 137Cs), pollen stratigraphy, and changes in sediment properties associated with human activity. Multiple methods are necessary because at any given site, problems arise in the assumptions or applicability of one or more methods. In general, the mass accumulation calculations suggest that sediments were deposited 4 to 11 times faster in the historic period than before human settlement. The character of the sediment did not change in a dramatic way, but sediment magnetic properties suggest shifts in the sources of sediment. The data suggest that some of the changes in sources and (or) character of the sediment occurred just before human settlement and were probably related to climatic changes

  8. Using lake sediment archives to evaluate late Holocene flood history

    NASA Astrophysics Data System (ADS)

    Chiverrell, R. C.; Foster, G. F.

    2009-04-01

    The sediment trapping efficiency offered by lakes should allow their sediments to reflect changes in discharge; however studies linking lake records with changing catchment hydrology are rare (e.g. Foster et al., 2003; 2008). Research examining sediments from the last 500 years from Loch of the Lowes (Tweed catchment) reveal variations in sediment properties that have been related to variations in transport capacity (flow regime). Small lakes with moderately sized catchments and limited capacity for upstream sediment storage appear to produce a strong coupling between the catchment and the lake, which appears essential for the system to record a flood stratigraphy. In northwest England and southwest Scotland land-use related woodland clearances have rendered upland landscapes susceptible to erosion. These conditions have produced lake sediment records for the last 4-2000 years dominated by catchment soils and sediments. Careful separation of grain size, geochemical and environmental magnetic parameters can identify suites of signals that reflect variations in both (1) supply and (2) the capacity of the system to transport materials to the lake. The capacity parameters (e.g. sand, HIRM and HIRM/XLF) broadly reflect changes in discharge, can be interpreted in terms of flood frequency. Preliminary data for the Loch of the Lowes basin in the central Southern Uplands of Scotland show a strong correlation with the North Atlantic Oscillation. There the capacity-related lake proxies appear to identify phases of increased flooding ~AD 1625-1650, 1680-1700, 1730-1760, 1800-1815, 1850-1880, 1910-1930, 1960-1970 and possibly the 1990s. Good correspondence between the sediment ‘flood' archive and historical records of flooding in Scotland suggests that lake-catchment systems of this type have the potential to yield valuable information on past hydrological response. These issues are developed in relation to other lakes in northwest England.

  9. Storm-induced redistribution of deepwater sediments in Lake Ontario

    USGS Publications Warehouse

    Halfman, J.D.; Dittman, D.E.; Owens, R.W.; Etherington, M.D.

    2006-01-01

    High-resolution seismic reflection profiles, side-scan sonar profiles, and surface sediment analyses for grain size (% sand, silt & clay), total organic carbon content, and carbonate content along shore-perpendicular transects offshore of Olcott and Rochester in Lake Ontario were utilized to investigate cm-thick sands or absence of deep-water postglacial sediments in water depths of 130 to 165 m. These deepwater sands were observed as each transect approached and occupied the "sills," identified by earlier researchers, between the three deepest basins of the lake. The results reveal thin (0 to 5-cm) postglacial sediments, lake floor lineations, and sand-rich, organic, and carbonate poor sediments at the deepwater sites (> 130 m) along both transects at depths significantly below wave base, epilimnetic currents, and internal wave activity. These sediments are anomalous compared to shallower sediments observed in this study and deeper sediments reported by earlier research, and are interpreted to indicate winnowing and resuspension of the postglacial muds. We hypothesize that the mid-lake confluence of the two-gyre surface current system set up by strong storm events extends down to the lake floor when the lake is isothermal, and resuspends and winnows lake floor sediment at these locations. Furthermore, we believe that sedimentation is more likely to be influenced by bottom currents at these at these sites than in the deeper basins because these sites are located on bathymetric highs between deeper depositional basins of the lake, and the bathymetric constriction may intensify any bottom current activity at these sites.

  10. /sup 137/Cs radioactive dating of Lake Ontario sediment cores

    SciTech Connect

    Ward, T.E.; Breeden, J.; Komisarcik, K.; Porter, R.; Czuczwa, J.; Kaminski, R.; McVeety, B.D.

    1987-12-01

    The distribution of /sup 137/Cs in sediment cores from Lake Ontario provides estimates of the sediment accumulation rates. Geochronology with /sup 210/Pb dating and distribution of Ambrosia (ragweed) pollen compare well with /sup 137/Cs dating. These methods can determine with precision, changes in sedimentation occurring over the past 100 years or so. Typical sedimentation rates of 0.18-0.36 cm/yr were measured. 16 refs., 3 figs., 2 tabs.

  11. Bioturbation enhances the aerobic respiration of lake sediments in warming lakes

    PubMed Central

    Krause, Stefan

    2016-01-01

    While lakes occupy less than 2% of the total surface of the Earth, they play a substantial role in global biogeochemical cycles. For instance, shallow lakes are important sites of carbon metabolism. Aerobic respiration is one of the important drivers of the carbon metabolism in lakes. In this context, bioturbation impacts of benthic animals (biological reworking of sediment matrix and ventilation of the sediment) on sediment aerobic respiration have previously been underestimated. Biological activity is likely to change over the course of a year due to seasonal changes of water temperatures. This study uses microcosm experiments to investigate how the impact of bioturbation (by Diptera, Chironomidae larvae) on lake sediment respiration changes when temperatures increase. While at 5°C, respiration in sediments with and without chironomids did not differ, at 30°C sediment respiration in microcosms with 2000 chironomids per m2 was 4.9 times higher than in uninhabited sediments. Our results indicate that lake water temperature increases could significantly enhance lake sediment respiration, which allows us to better understand seasonal changes in lake respiration and carbon metabolism as well as the potential impacts of global warming. PMID:27484649

  12. Spatial Patterns Study for Sediments from Lake Michigan

    EPA Science Inventory

    Accurately understanding the distribution of sediment measurements within large water bodies such as Lake Michigan is critical for modeling and understanding of carbon, nitrogen, silica and phosphorus dynamics. Several water quality models have been formulated and applied to the ...

  13. Microbial Diversity in Water and Sediment of Lake Chaka, an Athalassohaline Lake in Northwestern China

    PubMed Central

    Jiang, Hongchen; Dong, Hailiang; Zhang, Gengxin; Yu, Bingsong; Chapman, Leah R.; Fields, Matthew W.

    2006-01-01

    We employed culture-dependent and -independent techniques to study microbial diversity in Lake Chaka, a unique hypersaline lake (32.5% salinity) in northwest China. It is situated at 3,214 m above sea level in a dry climate. The average water depth is 2 to 3 cm. Halophilic isolates were obtained from the lake water, and halotolerant isolates were obtained from the shallow sediment. The isolates exhibited resistance to UV and gamma radiation. Microbial abundance in the sediments ranged from 108 cells/g at the water-sediment interface to 107 cells/g at a sediment depth of 42 cm. A major change in the bacterial community composition was observed across the interface. In the lake water, clone sequences affiliated with the Bacteroidetes were the most abundant, whereas in the sediments, sequences related to low G+C gram-positive bacteria were predominant. A similar change was also present in the archaeal community. While all archaeal clone sequences in the lake water belonged to the Halobacteriales, the majority of the sequences in the sediments were related to those previously obtained from methanogenic soils and sediments. The observed changes in the microbial community structure across the water-sediment interface were correlated with a decrease in salinity from the lake water (32.5%) to the sediments (approximately 4%). Across the interface, the redox state also changed from oxic to anoxic and may also have contributed to the observed shift in the microbial community. PMID:16751487

  14. 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...

  15. Small ecosystem engineers as important regulators of lake's sediment respiration.

    NASA Astrophysics Data System (ADS)

    Baranov, Victor; Lewandowski, Joerg; Krause, Stefan; Romeijn, Paul

    2016-04-01

    Although shallow lakes are covering only about 1.5% of the land surface of the Earth, they are responsible for sequestration of carbon amounts similar or even larger than those sequestered in all marine sediments. One of the most important drivers of the carbon sequestration in lakes is sediment respiration. Especially in shallow lakes, bioturbation, i.e. the biogenic reworking of the sediment matrix and the transport of fluids within the sediment, severely impacts on sediment respiration. Widespread freshwater bioturbators such as chironomid larvae (Diptera, Chironomidae) are building tubes in the sediment and actively pump water through their burrows (ventilation). In the present work we study how different organism densities and temperatures (5-30°C) impact on respiration rates. In a microcosm experiment the bioreactive resazurin/resorufin smart tracer system was applied for quantifying the impacts of different densities of Chironomidae (Diptera) larvae (0, 1000, 2000 larvae/m2) on sediment respiration. Tracer transformation rates (and sediment respiration) were correlated with larval densities with highest transformation rates occurring in microcosms with highest larval densities. Respiration differences between defaunated sediment and sediment with 1000 and 2000 larvae per m2 was insignificant at 5 °C, and was progressively increasing with rising temperatures. At 30 °C respiration rates of sediment with 2000 larvae per m2 was 4.8 times higher than those of defaunated sediment. We interpret this as an effect of temperature on larval metabolic and locomotory activity. Furthermore, bacterial communities are benefiting from the combination of the high water temperatures and bioirrigation as bacterial community are able to maintain high metabolic rates due to oxygen supplied by bioirrigation. In the context of global climate change that means that chironomid ecosystem engineering activity will have a profound and increasing impact on lake sediment respiration

  16. The Stratification Analysis of Sediment Data for Lake Michigan

    EPA Science Inventory

    This research paper describes the development of spatial statistical tools that are applied to investigate the spatial trends of sediment data sets for nutrients and carbon in Lake Michigan. All of the sediment data utilized in the present study was collected over a two year per...

  17. TOTAL AND BIOAVAILABLE METALS AT MARINA SEDIMENTS IN LAKE TEXOMA

    EPA Science Inventory

    Total and bioavailable metals in sediments were measured at marina areas in Lake Texoma during the fall of 2001. The metals most often found in the highest concentrations in sediments were Ca (56811 mg/kg) and Al (31095 mg/kg), followed by Fe (19393 mg/kg), K (6089 mg/kg), and Mg...

  18. Mississippi oxbow lake sediment quality during an artificial flood

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Surface sediment quality was assessed during a 35-day artificial flood in a shallow (<1.5 m) oxbow lake along the Coldwater River, Mississippi, using Hyalella azteca 28-day bioassays. Seventeen pesticides were monitored in sediments before, during and after flooding, with increases in atrazine and ...

  19. Activities and geochronology of (137)Cs in lake sediments resulting from sediment resuspension.

    PubMed

    Matisoff, Gerald

    2017-02-01

    In lakes with a large surface area to watershed ratio (137)Cs delivery is primarily by direct atmospheric fallout to the lake surface, where its activity in the sediments has been used to estimate the exposure to organisms and sediment mass deposition rates. Comparison of (137)Cs in the historical atmospheric fallout record with (137)Cs activity profiles in sediment cores reveals that although the general features of a maxima in the fallout deposition can be matched to activity peaks in the core, the general shape of the (137)Cs profile is not an exact replica of the fallout history. Instead, the sediment reflects post-depositional processes such as resuspension, bioturbation, partitioning of (137)Cs between the sediment solids and the pore fluids, and molecular diffusion of (137)Cs through the pore fluids. Presented here is a model that couples these processes to a system time averaging (STA) model that accounts for the time history of (137)Cs fallout and the particle residence time in the water column or in the 'active' surface sediment subject to resuspension. Sediment profiles are examined by comparing reasonable ranges of each of the coefficients of each of these major processes and by applying the model to cores collected from two large, shallow lakes, Lake Erie (USA/Canada) and Lake Winnipeg (Canada). The results indicate that the STA model with molecular diffusion and sediment resuspension best describes the data from these large, shallow lakes.

  20. Incorporation of Fine-Grained Sediment Erodibility Measurements into Sediment Transport Modeling, Capitol Lake, Washington

    USGS Publications Warehouse

    Stevens, Andrew W.; Gelfenbaum, Guy; Elias, Edwin; Jones, Craig

    2008-01-01

    Capitol Lake was created in 1951 with the construction of a concrete dam and control gate that prevented salt-water intrusion into the newly formed lake and regulated flow of the Deschutes River into southern Puget Sound. Physical processes associated with the former tidally dominated estuary were altered, and the dam structure itself likely caused an increase in retention of sediment flowing into the lake from the Deschutes River. Several efforts to manage sediment accumulation in the lake, including dredging and the construction of sediment traps upriver, failed to stop the lake from filling with sediment. The Deschutes Estuary Feasibility Study (DEFS) was carried out to evaluate the possibility of removing the dam and restoring estuarine processes as an alternative ongoing lake management. An important component of DEFS was the creation of a hydrodynamic and sediment transport model of the restored Deschutes Estuary. Results from model simulations indicated that estuarine processes would be restored under each of four restoration alternatives, and that over time, the restored estuary would have morphological features similar to the predam estuary. The model also predicted that after dam-removal, a large portion of the sediment eroded from the lake bottom would be deposited near the Port of Olympia and a marina located in lower Budd Inlet seaward of the present dam. The volume of sediment transported downstream was a critical piece of information that managers needed to estimate the total cost of the proposed restoration project. However, the ability of the model to predict the magnitude of sediment transport in general and, in particular, the volume of sediment deposition in the port and marina was limited by a lack of information on the erodibility of fine-grained sediments in Capitol Lake. Cores at several sites throughout Capitol Lake were collected between October 31 and November 1, 2007. The erodibility of sediments in the cores was later determined in the

  1. The evolution and distribution of methane in Lake Champlain sediments

    SciTech Connect

    Thibodeau, P.M. . Dept. of Geology)

    1993-03-01

    Regions of Lake Champlain sediments are acoustically impenetrable to the energy emitted from high resolution, low energy sub-bottom seismic profiling apparatus. This anomolous behavior is caused by the presence of interstitial methane gas which absorbs the wave energy and thus prevents the formation of well-defined seismic boundaries. Through gas chromatographic and carbon isotope analyses, the methane gas contained in the recent sediments of Lake Champlain has been demonstrated to be biogenic in origin. The production of biogenic methane occurs as a result of a series of coupled oxidation-reduction reactions occurring within the upper two meters beneath the sediment-water interface.

  2. Jellyfish Lake, Palau: early diagenesis of organic matter in sediments of an anoxic marine lake

    USGS Publications Warehouse

    Orem, W.H.; Burnett, W.C.; Landing, W.M.; Lyons, W.B.; Showers, W.

    1991-01-01

    The major postdepositional change in the sedimentary organic matter is carbohydrate biodegradation. Lignin and aliphatic substances are preserved in the sediments. Dissolved organic matter in pore waters is primarily composed of carbohydrates, reflecting the degradation of sedimentary carbohydrates. Rate constants for organic carbon degradation and sulfate reduction in sediments of the lake are about 10?? lower than in other anoxic sediments. This may reflect the vascular plant source and partly degraded nature of the organic matter reaching the sediments of the lake. -from Authors

  3. Phosphorus in sediment in the Kent Park Lake watershed, Johnson County, Iowa, 2014–15

    USGS Publications Warehouse

    Kalkhoff, Stephen J.

    2016-07-12

    Phosphorus data were collected from the Kent Park Lake watershed in Johnson County, Iowa, in 2014 and 2015 to obtain information to assist in the management of the water quality in the lake. Phosphorus concentrations were measured for sediment from several ponds in the watershed and sediment deposited in the lake. The first set of samples was collected in 2014 to understand phosphorus in several potential sources to the lake and the spatial variability in lake sediments. Phosphorus concentrations ranged from 68 to 380 milligrams per kilogram in lake sediment and from 57 to 220 milligrams per kilogram in sedimentation and dredge spoil ponds. Additional samples were collected in 2015 to determine how phosphorus concentrations vary with depth in the lake sediment. Phosphorus concentrations generally decreased with increasing depth within the lake sediment. In 2015, total phosphorus concentrations in lake sediment ranged from 50 to 340 milligrams per kilogram.

  4. Lake Hoare, Antarctica: sedimentation through a thick perennial ice cover

    NASA Technical Reports Server (NTRS)

    Squyres, S. W.; Andersen, D. W.; Nedell, S. S.; Wharton, R. A. Jr; Wharton RA, J. r. (Principal Investigator)

    1991-01-01

    Lake Hoare in the Dry Valleys of Antarctica is covered with a perennial ice cover more than 3 m thick, yet there is a complex record of sedimentation and of growth of microbial mats on the lake bottom. Rough topography on the ice covering the lake surface traps sand that is transported by the wind. In late summer, vertical conduits form by melting and fracturing, making the ice permeable to both liquid water and gases. Cross-sections of the ice cover show that sand is able to penetrate into and apparently through it by descending through these conduits. This is the primary sedimentation mechanism in the lake. Sediment traps retrieved from the lake bottom indicate that rates of deposition can vary by large amounts over lateral scales as small as 1 m. This conclusion is supported by cores taken in a 3 x 3 grid with a spacing of 1.5 m. Despite the close spacing of the cores, the poor stratigraphic correlation that is observed indicates substantial lateral variability in sedimentation rate. Apparently, sand descends into the lake from discrete, highly localized sources in the ice that may in some cases deposit a large amount of sand into the lake in a very short time. In some locations on the lake bottom, distinctive sand mounds have been formed by this process. They are primary sedimentary structures and appear unique to the perennially ice-covered lacustrine environment. In some locations they are tens of centimetres high and gently rounded with stable slopes; in others they reach approximately 1 m in height and have a conical shape with slopes at angle of repose. A simple formation model suggests that these differences can be explained by local variations in water depth and sedimentation rate. Rapid colonization of fresh sand surfaces by microbial mats composed of cyanobacteria, eukaryotic algae, and heterotrophic bacteria produces a complex intercalation of organic and sandy layers that are a distinctive form of modern stromatolites.

  5. Lake Hoare, Antarctica: sedimentation through a thick perennial ice cover.

    PubMed

    Squyres, S W; Andersen, D W; Nedell, S S; Wharton, R A

    1991-01-01

    Lake Hoare in the Dry Valleys of Antarctica is covered with a perennial ice cover more than 3 m thick, yet there is a complex record of sedimentation and of growth of microbial mats on the lake bottom. Rough topography on the ice covering the lake surface traps sand that is transported by the wind. In late summer, vertical conduits form by melting and fracturing, making the ice permeable to both liquid water and gases. Cross-sections of the ice cover show that sand is able to penetrate into and apparently through it by descending through these conduits. This is the primary sedimentation mechanism in the lake. Sediment traps retrieved from the lake bottom indicate that rates of deposition can vary by large amounts over lateral scales as small as 1 m. This conclusion is supported by cores taken in a 3 x 3 grid with a spacing of 1.5 m. Despite the close spacing of the cores, the poor stratigraphic correlation that is observed indicates substantial lateral variability in sedimentation rate. Apparently, sand descends into the lake from discrete, highly localized sources in the ice that may in some cases deposit a large amount of sand into the lake in a very short time. In some locations on the lake bottom, distinctive sand mounds have been formed by this process. They are primary sedimentary structures and appear unique to the perennially ice-covered lacustrine environment. In some locations they are tens of centimetres high and gently rounded with stable slopes; in others they reach approximately 1 m in height and have a conical shape with slopes at angle of repose. A simple formation model suggests that these differences can be explained by local variations in water depth and sedimentation rate. Rapid colonization of fresh sand surfaces by microbial mats composed of cyanobacteria, eukaryotic algae, and heterotrophic bacteria produces a complex intercalation of organic and sandy layers that are a distinctive form of modern stromatolites.

  6. Lake Disruptions on Sediment Mobility and Effects on Benthic Chlorophyll

    NASA Astrophysics Data System (ADS)

    Myers, A. K.; Marcarelli, A. M.; Arp, C. D.; Wurtsbaugh, W.; Baker, M. A.

    2005-05-01

    Watershed structure can have a profound effect on physical, chemical, and biological characteristics of streams. We investigated stream reaches above and below lakes in three watersheds that varied in the size and numbers of lakes in the Sawtooth Mountains to address how lakes affect sediment mobility and how this in turn affects algal biomass. During base flow, we gathered physical data such as pebble counts, stream geometry, and gradient to calculate sediment mobility. Chlorophyll a was measured as the biological response variable. We found that excess shear stress in lake outflows was <1, while excess shear stress was >1 in inflows, indicating that inflow sediments were mobile. Chlorophyll a concentrations were at least 10X greater at outflow sites compared to inflow sites. At one watershed where chlorophyll a was measured at a variety of sites on rocks of median sediment size (D50), there was a positive correlation between D50 and algal biomass (R2 =0.31, p=0.02). Other experiments indicated that lower chlorophyll a at inflow sites was due to increased bed mobility and not due to abrasion by bedload. Together, these results support the hypothesis that sediment trapping by lakes leads to increased substrate stability, and in turn allows increased periphyton growth.

  7. Calibration of biological lake sediment records: Tracing diatom assemblages through the water column into the sediment

    NASA Astrophysics Data System (ADS)

    Maier, Dominique; Gälman, Veronika; Bigler, Christian; Renberg, Ingemar

    2013-04-01

    Paleolimnological studies rely on sediment cores taken from the deepest point of a lake. The deposited sediment and its embedded biological record are expected to be chronological and to display the lakes ecological past. Therefore many studies use micropalaeontological approaches, since, e. g., unicellular organisms like diatoms are directly dependent on habitat changes and thus mirror the prevailing weather conditions. In this study we combine a set of diatom samples from freeze cores of a varved sediment, a sediment trap and bi-weekly plankton survey data with environmental data to calibrate the biological sediment record of a lake. The annually laminated sediment of the boreal forest lake Nylandssjön in northern Sweden provides a very high temporal resolution, which allows us, even on a seasonal scale, a gapless comparison between in situ production and the sediment deposition. Analysis of the diatom assemblages through the water column into the sediment is expected to reveal quantitative and qualitative miss match in deposition, resuspension, seasonal and interannual delays caused by physical events or autochtonous interactions such as grazing in the water column. The overall comparison of the ten year plankton net record and the corresponding sediment trap samples reveals large shifts from season to season but also from year to year. The sediment trap diatom record indicates comparable abundance patterns for the main taxa (Asterionella formosa and Tabellaria flocculosa). Peaks and seasonal shifts are less pronounced in the sediment trap compared to the plankton data. An overall difficulty lies in the comparison of volumes of water and sediment, concentrations and fluxes, which needs to be solved. However, subsequent comparison with the sediment diatom assemblage is expected to lead us to understand interannual taphonomic processes affecting diatom records within ten years in the naturally formed sediment layers. More importantly we will be able to discover

  8. Mercury empirical relationships in sediments from three Ontario lakes.

    PubMed

    Ethier, A L M; Scheuhammer, A M; Blais, J M; Paterson, A M; Mierle, G; Ingram, R; Lean, D R S

    2010-04-01

    Total mercury (THg), methyl mercury (MeHg), total organic carbon (TOC), sediment bulk density (SBD), redox potential (Eh) and percent fines measurements were made on sediment cores collected along transects from littoral to profundal depths in Harp, Dickie, and Blue Chalk lake located on the Canadian Shield near Dorset, Ontario, Canada to determine whether empirical relationships exist among these sediment properties. MeHg was positively correlated with THg in all sediments with a MeHg:THg ratio (0.004+/-0.004) comparable to other uncontaminated profundal lakes. MeHg, MeHg:THg and TOC decreased with sediment depth within the core for all lakes, whereas THg only showed a decrease in Harp Lake. MeHg:THg ratio in surficial sediments was positively correlated with Eh and negatively correlated with TOC [MeHg:THg=-0.009 TOC (%)+0.001 Eh (mV)-1.902, p=0.026]; whereas THg was positively correlated with TOC [log THg (ppb)=0.026 TOC (%)+1.400, p<0.0001].

  9. Geochemistry of sediments in cores and sediment traps from Bear Lake, Utah and Idaho

    USGS Publications Warehouse

    Bischoff, James L.; Cummins, Kathleen; Shamp, Donald D.

    2005-01-01

    The present study of Bear Lake began in 1998. Initially, the study utilized sediments from three long cores (up to 5 m) previously collected in 1996 and short cores (up to 40 cm) collected in 1998. The short cores were specifically acquired to preserve the uppermost layers of sediment that may have been lost in the long cores. In addition, three arrays of sediment traps were deployed during the summer of 1998, and sediment from these traps was collected during the summers of 1999 and 2000 (see Dean and others, 2005, for core and sediment trap locations). The cores and sediment traps were sampled, and splits were distributed to various investigators for analyses of a wide variety of sediment parameters. The chemical composition of the acid-soluble component of the sediments is presented in this report. HCl or HNO3 treatment of the sediment quantitatively dissolves the authigenic component of the sediment, a component that includes carbonates, sulfates, and iron-mono sulfides. In the case of Bear Lake, CaCO3 is the major component of the sediment today and for most of the Holocene (Dean and others 2005). The chemical composition of the acid-soluble fraction gives important information on this component and, therefore, insight into the chemical conditions of the lake at the time of carbonate deposition.

  10. Modern processes of sediment formation in Lake Towuti, Indonesia, as derived from the composition of lake surface sediments

    NASA Astrophysics Data System (ADS)

    Hasberg, Ascelina; Melles, Martin; Morlock, Marina; Vogel, Hendrik; Russel, James M.; Bijaksana, Satria

    2016-04-01

    In summer 2015, a drilling operation funded by the International Continental Scientific Drilling Program (ICDP) was conducted at Lake Towuti (2.75°S, 121.5°E), the largest tectonically formed lake (surface area: 561 km²) of the Republic Indonesia. The Towuti Drilling Project (TDP) recovered more than 1000 meters of sediment core from three sites. At all three sites replicate cores down to 133, 154, and 174 m below lake floor have penetrated the entire lake sediment record, which is expected to comprise the past ca. 650.000 years continuously. Lake Towutís sediment record thus can provide unique information for instance concerning the climatic and environmental history in the Indo-Pacific-Warm-Pool (IPWP) and concerning the evolutionary biology in SE Asia. For a better understanding of the palaeoenvironmental proxies to be analyzed on the drill cores, the modern processes of sediment formation in the lake and in its catchment - under known environmental conditions - were investigated on a set of 84 lake sediment surface samples. Sampling was conducted by grab sampler (UWITEC Corp., Austria) in a grid of 1 to 4 km resolution that covers the entire lake. The samples were analyzed for inorganic geochemical composition (XRF powder scans and ICP-MS), magnetic susceptibility (Kappabridge), grain-size distribution (laser scanner), biogenic components (smear-slide analyses), biogenic silica contents (leaching), and carbonate, total organic carbon (TOC), nitrogen (TN), and sulfur (TS) concentrations (elemental analyzer). The sediments close to the lake shores and in front of the major river inlets are characterized by mean grain sizes coarser than average and high magnetic susceptibilities presented by high ratios of Cr, Ni, Co, and Zr. This reflects higher energies due to wave action and fluvial sediment supply, as well as the occurrence of magnetic minerals particularly in the sand and gravel fractions of the sediments. In regions of deeper waters and more distal to

  11. Geochemistry and Mineralogy of Western Australian Salt Lake Sediments: Implications for Meridiani Planum on Mars

    NASA Astrophysics Data System (ADS)

    Ruecker, A.; Schröder, C.; Byrne, J.; Weigold, P.; Behrens, S.; Kappler, A.

    2016-07-01

    Hypersaline lakes are characteristic for Western Australia and display a rare combination of geochemical and mineralogical properties that make these lakes potential analogues for past conditions on Mars. In our study, we focused on the geochemistry and mineralogy of Lake Orr and Lake Whurr. While both lakes are poor in organic carbon (<1%), the sediments' pH values differ and range from 3.8 to 4.8 in Lake Orr and from 5.4 to 6.3 in Lake Whurr sediments. Lake Whurr sediments were dominated by orange and red sediment zones in which the main Fe minerals were identified as hematite, goethite, and tentatively jarosite and pyrite. Lake Orr was dominated by brownish and blackish sediments where the main Fe minerals were goethite and another paramagnetic Fe(III)-phase that could not be identified. Furthermore, a likely secondary Fe(II)-phase was observed in Lake Orr sediments. The mineralogy of these two salt lakes in the sampling area is strongly influenced by events such as flooding, evaporation, and desiccation, processes that explain at least to some extent the observed differences between Lake Orr and Lake Whurr. The iron mineralogy of Lake Whurr sediments and the high salinity make this lake a suitable analogue for Meridiani Planum on Mars, and in particular the tentative identification of pyrite in Lake Whurr sediments has implications for the interpretation of the Fe mineralogy of Meridiani Planum sediments.

  12. Covering bottom sediments as a lake restoration technique

    SciTech Connect

    Cooke, G.D.

    1980-10-01

    Application of flyash to lake bottoms as a lake restoration technique is discussed. Flyash application could control microorganisms and sediment nutrients associated with eutrophication; however, use of flyash would present more environmental costs than benefits. PVC-coated screens and spun-bonded polypropylene screens are acceptable, but costly, alternatives to flyash application. Use of sand, clay, or other sheeting to retard eutrophication should be investigated. 28 references, 3 tables.

  13. Pleistocene sediments of Lake Baikal: Lithology and stratigraphic correlation

    NASA Astrophysics Data System (ADS)

    Akulov, N. I.; Mashchuk, I. M.; Akulova, V. V.

    2015-01-01

    The Cenozoic sediments of Lake Baikal penetrated by boreholes and investigated by the manned submersible Pisces, as well as coeval deposits cropping out in beach scarps, recovered by mine workings, and drilled in the coastal zone were the object of this investigation. The main attention was paid to Pleistocene bottom sediments penetrated by Borehole BDP-99-2. The investigations included the detailed analysis of the lithology (grain-size composition, immersion mineralogy of light and heavy fractions, X-ray structural analysis of clayey fraction) and palynological assemblages to specify facies features of Cenozoic sediments, correlate all their known stratigraphic units constituting the sedimentary section of the lake with their analogs in the onshore part of the Baikal rift zone, and compile the composite Cenozoic section. The following features of these sediments are noted: (1) as a whole, Pleistocene sediments are characterized by the hydromica-smectite composition of their clayey fraction with an insignificant share of kaoline; (2) the heavy fraction is dominated by the terrigenous epidote-amphibole association poorly resistant to weathering; (3) Pleistocene sediments of the lake contain siderite, vivianite, pyrite, and goethite concretions and micrometeorites, in addition to well-known ferromanganese nodules; (4) the presence of relict palynomorphs in Pleistocene sediments of Baikal is determined by their erosion from Miocene and Pliocene cavernous clays cropping out on underwater slopes of the Posol'skaya Bank and subsequent reburial along with Pleistocene palynological assemblages.

  14. ORGANOCHLORINE PESTICIDES AND POLYCHLORINATED BIPHENYLS (PCBS) IN SEDIMENTS AND BIOTA FROM FOUR US ARCTIC LAKES

    EPA Science Inventory

    Organochlorine (OC) concentrations in surface sediment, snails (Lymnea sp.), and two freshwater fish species (grayling, Thymallus arcticus; and lake trout, Salvelinus namaycush) from four lakes in the US Arctic were determined. In surface sediment, chlorinated benzenes (including...

  15. HEAVY METAL ACCUMULATION IN SEDIMENT AND FRESHWATER FISH IN U.S. ARCTIC LAKES

    EPA Science Inventory

    Metal concentrations in sediment and two species of freshwater fish (lake trout [Salvelinus namaycush], and grayling [Thymallus arcticus]} were examined in four Arctic lakes in Alaska. Concentrations of several metals were naturally high in the sediment relative to uncontaminated...

  16. The carbon cycle and biogeochemical dynamics in lake sediments

    USGS Publications Warehouse

    Dean, W.E.

    1999-01-01

    The concentrations of organic carbon (OC) and CaCO3 in lake sediments are often inversely related. This relation occurs in surface sediments from different locations in the same lake, surface sediments from different lakes, and with depth in Holocene sediments. Where data on accumulation rates are available, the relation holds for organic carbon and CaCO3 accumulation rates as well. An increase of several percent OC is accompanied by a decrease of several tens of percent CaCO3 indicating that the inverse relation is not due to simple dilution of one component by another. It appears from core data that once the OC concentration in the sediments becomes greater than about 12%, the CO2 produced by decomposition of that OC and production of organic acids lowers the pH of anoxic pore waters enough to dissolve any CaCO3 that reaches the sediment-water interface. In a lake with a seasonally anoxic hypolimnion, processes in the water column also can produce an inverse relation between OC and CaCO3 over time. If productivity of the lake increases, the rain rate of OC from the epilimnion increases. Biogenic removal of CO2 and accompanying increase in pH also may increase the production of CaCO3. However, the decomposition of organic matter in the hypolimnion will decrease the pH of the hypolimnion causing greater dissolution of CaCO3 and therefore a decrease in the rain rate of CaCO3 to the sediment-water interface.

  17. A conduit dilation model of methane venting from lake sediments

    USGS Publications Warehouse

    Scandella, B.P.; Varadharajan, C.; Hemond, Harold F.; Ruppel, C.; Juanes, R.

    2011-01-01

    Methane is a potent greenhouse gas, but its effects on Earth's climate remain poorly constrained, in part due to uncertainties in global methane fluxes to the atmosphere. An important source of atmospheric methane is the methane generated in organic-rich sediments underlying surface water bodies, including lakes, wetlands, and the ocean. The fraction of the methane that reaches the atmosphere depends critically on the mode and spatiotemporal characteristics of free-gas venting from the underlying sediments. Here we propose that methane transport in lake sediments is controlled by dynamic conduits, which dilate and release gas as the falling hydrostatic pressure reduces the effective stress below the tensile strength of the sediments. We test our model against a four-month record of hydrostatic load and methane flux in Upper Mystic Lake, Mass., USA, and show that it captures the complex episodicity of methane ebullition. Our quantitative conceptualization opens the door to integrated modeling of methane transport to constrain global methane release from lakes and other shallow-water, organic-rich sediment systems, and to assess its climate feedbacks.

  18. A conduit dilation model of methane venting from lake sediments

    NASA Astrophysics Data System (ADS)

    Scandella, Benjamin P.; Varadharajan, Charuleka; Hemond, Harold F.; Ruppel, Carolyn; Juanes, Ruben

    2011-03-01

    Methane is a potent greenhouse gas, but its effects on Earth's climate remain poorly constrained, in part due to uncertainties in global methane fluxes to the atmosphere. An important source of atmospheric methane is the methane generated in organic-rich sediments underlying surface water bodies, including lakes, wetlands, and the ocean. The fraction of the methane that reaches the atmosphere depends critically on the mode and spatiotemporal characteristics of free-gas venting from the underlying sediments. Here we propose that methane transport in lake sediments is controlled by dynamic conduits, which dilate and release gas as the falling hydrostatic pressure reduces the effective stress below the tensile strength of the sediments. We test our model against a four-month record of hydrostatic load and methane flux in Upper Mystic Lake, Mass., USA, and show that it captures the complex episodicity of methane ebullition. Our quantitative conceptualization opens the door to integrated modeling of methane transport to constrain global methane release from lakes and other shallow-water, organic-rich sediment systems, and to assess its climate feedbacks.

  19. Dynamics of suspended sediment plumes in Lake Ontario

    NASA Technical Reports Server (NTRS)

    Pluhowski, E. J. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. Enhancement of ERTS-1 imagery yielded excellent quality 35-mm color slides and prints of several prominent turbidity plumes in Lake Ontario. Selected ERTS-1 frames of the Welland Canal and Genesee River plumes will be used to develop time-lapse sequences showing the impact of wind stress on each plume. Unusually high lake levels during the spring resulted in extensive beach erosion along the entire Lake Ontario shoreline. The resulting high concentrations of suspended matter generated highly turbid (up to 420 JTU) nearshore conditions that appeared milky white in the imagery obtained April 12 and 29th, 1973. During the shipping season, both the Welland Canal and a diversion channel at Port Dalhousie, Ontario, produced readily identifiable turbidity plumes in Lake Ontario. However, in the winter neither plume was visible in the ERTS-1 imagery suggesting sharply lower sediment discharge into Lake Ontario from these sources.

  20. Sedimentation rates and pollution history of a dried lake: Al-Oteibeh Lake.

    PubMed

    Al-Masri, M S; Aba, A; Khalil, H; Al-Hares, Z

    2002-07-03

    Sediment accumulation rates as well as the distribution of selected elements in a dried Syrian lake (Al-Oteibeh Lake), near Damascus City, are reported. Five core samples from different locations of the lake were collected, and four major elements (Fe, K, Mg and Na) and six trace metals (Co, Ni, Cr, Pb, Zn, U and Cu) were analyzed. Sedimentation rates were determined applying the 210Pb dating method and found to vary between 0.100 and 0.793 cm year(-1). The results showed that the constant flux constant sedimentation rate (CF:CS) simple dating model is applicable for dating recent dried sediment and recording the past historical pollution of the last 100 years. However, the method was found to be only applicable for dating trace and major elements, which cannot be leached to deeper layers by rainwater. In addition, the obtained records can be used to verify the date of water level declining.

  1. Microbial Aldicarb Transformation in Aquifer, Lake, and Salt Marsh Sediments

    PubMed Central

    Kazumi, J.; Capone, D. G.

    1995-01-01

    The microbial transformation of [N-methyl-(sup14)C]aldicarb, a carbamate pesticide, occurred in aquifer, lake, and salt marsh sediments. Microbial degradation of aldicarb took place within 21 days in aquifer sediments from sites previously exposed to aldicarb (Jamesport, Long Island, N.Y.) but did not occur in sediments which were not previously exposed (Connetquot State Park, Long Island, N.Y.). At the Jamesport sites, higher aldicarb transformation rates occurred in deep, anoxic sediments than in shallow, oxic sediments. There was a significant negative relationship (P < 0.05) between transformation rates and ambient dissolved O(inf2) levels. Aldicarb hydrolysis rates in Jamesport sediments were 10- to 1,000-fold lower than rates previously reported for soils. In addition, aldicarb degradation rates were not significantly correlated with measurements of bacterial activity and density previously determined in the same sediments. Substantially higher aldicarb degradation rates were found in anoxic lake and salt marsh than in aquifer sediments. Furthermore, we investigated the anaerobic microbial processes involved in aldicarb transformation by adding organic substrates (acetate, glucose), an alternative electron acceptor (nitrate), and microbial inhibitors (molybdate, 2-bromoethanesulfonic acid) to anoxic aquifer, lake, and salt marsh sediments. The results suggest that a methanogenic consortium was important in aldicarb transformation or in the use of aldicarb-derived products such as methylamine. In addition, microbial aldicarb transformation proceeded via different pathways under oxic and anoxic conditions. In the presence of O(inf2), aldicarb transformation was mainly via an oxidation pathway, while in the absence of O(inf2), degradation took place through a hydrolytic pathway (including the formation of methylamine precursors). Under anoxic conditions, therefore, aldicarb can be transformed by microbial consortia to yield products which can be of direct

  2. Measurement of Mercury Methylation in Lake Water and Sediment Samples

    PubMed Central

    Furutani, Akira; Rudd, John W. M.

    1980-01-01

    Biological mercury methylation was assayed by a new radiochemical technique in the water column and sediments of a mercury-contaminated lake. In 24 weeks during 1979, there were three episodes of methylating activity in surface floc and in water, each lasting 3 to 5 weeks. Periods of methylation in the water column coincided with surface sediment methylation and appeared to be related to overall microbial activity. Mercury was actively methylated in the presence of bound sulfide. PMID:16345649

  3. 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

  4. Last millenium environmental changes in Lake Bertrand sediments, Chilean Patagonia

    NASA Astrophysics Data System (ADS)

    Sacré, V.; Fagel, N.; Schmidt, S.; Alvarez, D.; Araneda, A.; Urrutia, R.

    2012-04-01

    Our study focuses on a multiproxy analysis of sedimentary records from Lago Bertrand (area 50 km2; 227 masl; 46°55'S 72°50'W). Three cores were retrieved during fieldtrips in 2009 and 2011 with an Uwitec gravity corer. One core was collected in the main lake (LBt09, 102 cm) and two others in a lateral extension (LBb11-A, 162 cm and LBb11-B, 156 cm). Data 210Pb and 137Cs give average sedimentation rates of 2 mm/yr for the upper core section from the main lake, allowing a decennial resolution. Our aim is to document the climatic variability during the last millennium in Northern Patagonia and its impact on the environment. Lago Bertrand is separated from a pro-glacial lake (Lago Plomo) by a morainic barrier. The sediments of this lake are mainly composed of clayed silts and very few sandy silts. In the cores from the Eastern branch of Lago Bertrand, X-ray radiographies and magnetic susceptibility profiles evidence well-defined pluri-millimetric laminations with organic-rich layers, especially in the central core section. In the main lake, X-ray radiographies show diffuse pluri-millimetric laminations while magnetic susceptibility profiles do not confirm it. The sediments of the main lake appear more homogeneous with less organic-rich layers. They are characterized by low C/N ratio (10), supporting an important aquatic productivity; high inorganic content (90-95% of the bulk sediment); two peaks in the biological silica profile; and abundant diatoms (50-100 µm). According to the age model, the changes in aquatic productivity occurred between 1700 and 1850 AD. The cores from the Eastern branch of Lago Bertrand are under investigation to confirm the extension of the sedimentological changes observed in the main lake. The main sedimentological change observed in Lago Bertrand occurs during an interval equivalent to a part of the Little Ice Age. A similar biogenic silica-rich layer was also recorded in another relatively distant lake (Lago Thompson at 45°30'S, 72°47

  5. Hydrologic and suspended-sediment data for Reelfoot Lake, Obion and Lake Counties, northwestern Tennessee, May 1985-September 1986

    USGS Publications Warehouse

    Garrett, J.W.

    1988-01-01

    Hydrologic data for Reelfoot Lake in Obion and Lake Counties, Tennessee, were collected at 4 surface water inflow stations, 1 outflow station, 2 rainfall stations, 2 lake elevation stations, and 29 wells for the period May 1, 1985 through September 30, 1986. Additionally, suspended-sediment data were collected at three stations on two of the major tributaries to the lake. (USGS)

  6. Reductive dechlorination of chlorophenols in estuarine sediments of Lake Shinji and Lake Nakaumi.

    PubMed

    Itoh, Kazuhito; Mihara, Yoichi; Tanimoto, Naoya; Shimada, Tetsuo; Suyama, Kousuke

    2010-07-01

    Dechlorination of all mono- and dichlorophenol isomers in anaerobic sediment samples of estuarine Lake Shinji and Lake Nakaumi was examined to characterize the chlorophenol-dechlorinating microbial communities in the environments with different salinity levels. Dechlorination was observed only in 2-chlorophenol (2-CP), 3-chlorophenol (3-CP) and 2,6-dichlorophenol (2,6-DCP), and in 2-CP and 2,6-DCP in the Lake Shinji and Nakaumi sediment, respectively. In the sediment of Lake Shinji, the highest activity was observed without adding sodium chloride and sulfate, whereas in the Lake Nakaumi sediment, the highest activity was at 0.7 % of sodium chloride and 6.0 mM of sodium sulfate. The chlorophenols were degraded to benzoate via phenol in both sediments under methanogenic conditions. Benzoate then disappeared from the cultures. All microbial consortia enriched with each monochlorophenol dechlorinated 2-CP, but showed different substrate specificities for dichlorophenols as follows: 2-CP-enriched consortium dechlorinated 2,3-dichlorophenol and 2,6-DCP, 3-CP-enriched consortium dechlorinated all dichlorophenol isomers, and 4-chlorophenol-enriched consortium dechlorinated 2,4-dichlorophenol and 2,6-DCP. Maintenance of the population by halorespiration was suggested in the dechlorination of 2-CP.

  7. Catchment sediment flux: a lake sediment perspective on the onset of the Anthropocene?

    NASA Astrophysics Data System (ADS)

    Chiverrell, Richard

    2014-05-01

    Definitions of the Anthropocene are varied but from a geomorphological perspective broadly can be described as the interval of recent Earth history during which 'humans have had an 'overwhelming' effect on the Earth system' (Brown et al., 2013). Identifying the switch to a human-dominated geomorphic process regime is actually a challenging process, with in the 'Old World' ramping up of human populations and impacts on earth surface processes since the Neolithic/Mesolithic transition and the onset of agriculture. In the terrestrial realm lakes offer a unique window on changes in human forcing of earth surface processes from a sedimentary flux perspective, because unlike alluvial and hill-slope systems sedimentation is broadly continuous and uninterrupted. Dearing and Jones (2003) showed for a global dataset of lakes a 5-10 fold increase in sediment delivery comparing pre- and post-anthropogenic disturbance. Here sediment records from several lakes in lowland agricultural landscapes are presented to examine the changes in the flux and composition of materials delivered from their catchments. By definition the lakes record the switch to a human dominated system, but not necessary in accelerated sediment accumulation rates with changes in sediment composition equally important. Data from Crose, Hatch and Peckforton Meres, in lowland northwest England are interrogated producing quantitative land-cover reconstructions from pollen spectra calculated using the REVEALS model (Sugita, 2007), geochemical evidence for changes sediment provenance and flux, and 14C and stable Pb pollutant based chronological models detecting changes in sediment accumulation rate. The lake sediment geochemistry points to several phases of heightened human impact within these small agricultural catchments. Following small-in-scale forest cover reductions and limited impacts in terms of sediment flux during the Neolithic, the Bronze to Iron Age saw the first substantial reductions in forest cover

  8. 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...

  9. Magnetic and geochemical signatures of flood layers in lake sediments

    NASA Astrophysics Data System (ADS)

    Støren, Eivind; Paasche, Øyvind; Hirt, Ann; Kumari, Monika

    2016-04-01

    Floods carry sediments that quickly become deposited whenever rivers meet lakes. In catchments that are subjected to repeated flooding, downstream lakes can therefore contain record of past events across multiple timescales. High-resolution core scanning analyses such as X-ray fluorescence (XRF) scanning and magnetic susceptibility (MS) return data that are frequently used to detect flood layers in soft sediment archives such as lakes, fjords and ocean basins. In order to delineate the copious information that can be extracted from soft sediment records we have explored ways in which high-resolution data can be utilized and subsequently vetted by high-precision measurements. By combining magnetic hysteresis measurements and first-order reversal curves (FORCs) with inductively coupled plasma optical emission spectrometer (ICP-OES) measurements of chemical elements on 36 samples, important information not only about flood dynamics and variability are acquired, but also sources of noise in high-resolution scanning techniques are identified. Specifically, we show that a lake flood record from Southern Norway containing ˜ 100 floods distributed over 10 000 years can be sub-divided into at least two groups, suggested to contain floods generated by spring snow melting and intense summer rainstorms. The temporal evolution of this pattern shows a marked shift towards spring floods around 2000 years ago compared to the earlier part of the record. The approach presented here is of universal character and should be applicable to all kinds of soft sediment archives.

  10. A Composite Depth Scale for Sediments from Crevice Lake, Montana

    USGS Publications Warehouse

    Rosenbaum, J.G.; Skipp, G.; Honke, J.; Chapman, C.

    2010-01-01

    As part of a study to derive records of past environmental change from lake sediments in the western United States, a set of cores was collected from Crevice Lake, Montana, in late February and early March 2001. Crevice Lake (latitude 45.000N, longitude 110.578W, elevation 1,713 meters) lies adjacent to the Yellowstone River at the north edge of Yellowstone National Park. The lake is more than 31 meters deep and has a surface area of 7.76 hectares. The combination of small surface area and significant depth promote anoxic bottom-water conditions that preserve annual laminations (varves) in the sediment. Three types of cores were collected through the ice. The uppermost sediments were obtained in freeze cores that preserved the sediment water interface. Two sites were cored with a 5-centimeter diameter corer. Five cores were taken with a 2-meter-long percussion piston corer. The percussion core uses a plastic core liner with an inside diameter of 9 centimeters. Coring was done at two sites. Because of the relatively large diameter of the percussion cores, samples from these cores were used for a variety of analyses including pollen, charcoal, diatoms, stable isotopes, organic and inorganic carbon, elemental analyses, and magnetic properties.

  11. Sediment magnetic and paleomagnetic data from Buck Lake, Oregon

    USGS Publications Warehouse

    Rosenbaum, J.G.; Reynolds, R.L.; Fitzmaurice, P.L.; Drexler, J.W.; Whitney, C.G.; Adam, D.P.

    1994-01-01

    Sediment magnetic and paleomagnetic studies were conducted on a core from Buck Lake, Klamath County, Oregon, that was collected as part of an investigation into the Quaternary climate history of the western United States. This report documents the methods used to obtain paleomagnetic directions, magnetic properties, and ancillary data, and presents these data in tabular form. Adam (1993) and Adam and others (1994) describe the site, the drilling methods, and lithology of the lacustrine sediments. Rosenbaum and others (1994) present preliminary interpretations of the sediment magnetic data and show that variations in magnetic properties closely reflect changes in climate as interpreted from the pollen record.

  12. Multi-Elements in Waters and Sediments of Shallow Lakes: Relationships with Water, Sediment, and Watershed Characteristics

    PubMed Central

    Jacob, Donna L.; Hanson, Mark A.; Herwig, Brian R.; Bowe, Shane E.; Otte, Marinus L.

    2015-01-01

    We measured concentrations of multiple elements, including rare earth elements, in waters and sediments of 38 shallow lakes of varying turbidity and macrophyte cover in the Prairie Parkland (PP) and Laurentian Mixed Forest (LMF) provinces of Minnesota. PP shallow lakes had higher element concentrations in waters and sediments compared to LMF sites. Redundancy analysis indicated that a combination of site- and watershed-scale features explained a large proportion of among-lake variability in element concentrations in lake water and sediments. Percent woodland cover in watersheds, turbidity, open water area, and macrophyte cover collectively explained 65.2 % of variation in element concentrations in lake waters. Sediment fraction smaller than 63 µm, percent woodland in watersheds, open water area, and sediment organic matter collectively explained 64.2 % of variation in element concentrations in lake sediments. In contrast to earlier work on shallow lakes, our results showed the extent to which multiple elements in shallow lake waters and sediments were influenced by a combination of variables including sediment characteristics, lake morphology, and percent land cover in watersheds. These results are informative because they help illustrate the extent of functional connectivity between shallow lakes and adjacent lands within these lake watersheds. PMID:26074657

  13. Phosphorus flux from bottom sediments in Lake Eucha, Oklahoma.

    PubMed

    Haggard, B E; Moore, P A; Delaune, P B

    2005-01-01

    Phosphorus inputs into reservoirs include external sources from the watershed and internal sources from the reservoir bottom sediments. This study quantified sediment P flux in Lake Eucha, northeastern Oklahoma, USA, and evaluated the effectiveness of chemical treatment to reduce sediment P flux. Six intact sediment-water columns were collected from three sites in Lake Eucha near the reservoir channel at depths of 10 to 15 m. Three intact sediment and water columns from each site were incubated for 21 d at approximately 22 degrees C under aerobic conditions, and three were incubated under anaerobic conditions (N2 with 300 ppm CO2); sediment P flux was estimated over the 21 d for each core. The overlying water in the cores was bubbled with air for approximately 1 wk and then treated with aluminum sulfate (alum). The cores were incubated at approximately 22 degrees C for an additional 14 d under aerobic or anaerobic conditions, and sediment P flux after alum treatment was estimated for each core. Sediment P flux was approximately four times greater under anaerobic conditions compared with aerobic conditions. Alum treatment of the intact sediment-water columns reduced (8x) sediment P flux under anaerobic conditions. Internal P flux (1.03 and 4.40 mg m(-2) d(-1) under aerobic and anaerobic conditions, respectively) was greater than external P flux (0.13 mg m(-2) d(-1)). The internal P load (12 Mg yr(-1)) from reservoir bottom sediments was almost 25% of the external P load (approximately 48 Mg yr(-1)) estimated using a calibrated watershed model.

  14. Sediment toxicity testing of Lake Orta after liming

    SciTech Connect

    Baudo, R.; Beltrami, M.; Rossi, D.; Gronda, A.; Abdel-Monem, A.M.; Burton, G.A.

    1995-12-31

    Lake Orta has been severely polluted by industrial effluents containing Cu, NH{sub 3}, Cr., Ni, and Zn. Ammonia oxidation caused a pH drop below 4. More than 60 papers have described the adverse chemical and biological changes which occurred in Lake Orta in the past several decades. In 1989, CaCO{sub 3} (10,900 tons) was added to the lake as a remedial action. The treatment was effective, improving water quality and allowing some original plankton, benthic, and fish populations to return. However, Cu and Cr are still present in the top 10 cm of sediment. The toxicity of the sediment was evaluated using multiple assays: Microtox (solid phase and pore water), Brachionus calyciflorus and Thamnocephalus platyurus Toxkits (pore water), seed germination and root elongation (solid phase and pore water). In addition, in situ and laboratory tests were conducted with Hyalella azteca and an indigenous species of Daphnia. Assays responses varied yet showed surficial sediments to be toxic. Toxicity increased with sediment in pre-liming deposition zones. Recovery of the ecosystem is evident, however the contaminated sediments may impede further improvement.

  15. Assessing contamination in Great Lakes sediments using benthic invertebrate communities and the sediment quality triad approach

    USGS Publications Warehouse

    Canfield, Timothy J.; Dwyer, F. James; Fairchild, James F.; Haverland, Pamela S.; Ingersoll, Christopher G.; Kemble, Nile E.; Mount, David R.; La Point, Thomas W.; Burton, G. Allen; Swift, M. C.

    1996-01-01

    Sediments in many Great Lakes harbors and tributary rivers are contaminated. As part of the USEPA's Assessment and Remediation of Contaminated Sediment (ARCS) program, a number of studies were conducted to determine the nature and extent of sediment contamination in Great Lakes Areas of Concern (AOC). This paper describes the composition of benthic invertebrate communities in contaminated sediments and is one in a series of papers describing studies conducted to evaluate sediment toxicity from three AOC's (Buffalo River, NY; Indiana Harbor, IN; Saginaw River, MI), as part of the ARCS Program. Oligochaeta (worms) and Chironomidae (midge) comprised over 90% of the benthic invertebrate numbers in samples collected from depositional areas. Worms and midge consisted of taxa identified as primarily contaminant tolerant organisms. Structural deformities of mouthparts in midge larvae were pronounced in many of the samples. Good concurrence was evident between measures of laboratory toxicity, sediment contaminant concentration, and benthic invertebrate community composition in extremely contaminated samples. However, in moderately contaminated samples, less concordance was observed between the benthos community composition and either laboratory toxicity test results or sediment contaminant concentration. Laboratory sediment toxicity tests may better identify chemical contamination in sediments than many commonly used measures of benthic invertebrate community composition. Benthic measures may also reflect other factors such as habitat alteration. Evaluation of non-contaminant factors are needed to better interpret the response of benthic invertebrates to sediment contamination.

  16. Human land uses enhance sediment denitrification and N2O production in Yangtze lakes primarily by influencing lake water quality

    NASA Astrophysics Data System (ADS)

    Liu, W.; Yao, L.; Wang, Z.; Xiong, Z.; Liu, G.

    2015-10-01

    Sediment denitrification in lakes alleviates the effects of eutrophication through the removal of nitrogen to the atmosphere as N2O and N2. However, N2O contributes notably to the greenhouse effect and global warming. Human land uses (e.g. agricultural and urban areas) strongly affect lake water quality and sediment characteristics, which, in turn, may regulate lake sediment denitrification and N2O production. In this study, we investigated sediment denitrification and N2O production and their relationships to within-lake variables and watershed land uses in 20 lakes from the Yangtze River basin in China. The results indicated that both lake water quality and sediment characteristics were significantly influenced by watershed land uses. N2O production rates increased with increasing background denitrification rates. Background denitrification and N2O production rates were positively related to water nitrogen concentrations but were not significantly correlated with sediment characteristics and plant community structure. A significant positive relationship was observed between background denitrification rate and percentage of human-dominated land uses (HDL) in watersheds. Structural equation modelling revealed that the indirect effects of HDL on sediment denitrification and N2O production in Yangtze lakes were mediated primarily through lake water quality. Our findings also suggest that although sediments in Yangtze lakes can remove large quantities of nitrogen through denitrification, they may also be an important source of N2O, especially in lakes with high nitrogen content.

  17. 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

  18. Influence of trophic status on PCB distribution in lake sediments and biota.

    PubMed

    Berglund, O; Larsson, P; Ewald, G; Okla, L

    2001-01-01

    We investigated the relationship between trophic status and polychlorinated biphenyl (PCB) distribution in 19 Swedish lakes. We analyzed PCB in water, phytoplankton, zooplankton, fish and sediment during two sampling periods, in spring and summer. The mass of sigma PCB in the lake sediments was positively related to lake trophy, i.e. more PCBs were accumulated and buried in the sediment of eutrophic lakes than in oligotrophic lakes. In the oligotrophic lakes a greater fraction of the total PCB load was dissolved in water. We conclude that this is a result of higher sedimentation rates in eutrophic lakes and relatively lower turnover of organic carbon in the water column of the shallow, eutrophic lakes. In the stratified lakes, the amount of PCB per cubic meter in the epilimnion decreased from spring to summer. We suggest that sedimentation of plankton beneath the thermocline during stratification act as a sink process of PCBs from the epilimnion.

  19. Survival of Escherichia coli in lake bottom sediment.

    PubMed Central

    LaLiberte, P; Grimes, D J

    1982-01-01

    The survival of Escherichia coli in bottom sediment (Lake Onalaska, navigation pool no. 7, Mississippi River) was studied by using in situ dialysis culture of sterile (autoclaved) and unsterile sediment samples. Bags made from dialysis tubing were filled with either course sand sediment (28.8% fine) or organic, silty clay sediment (77.2% fine) and placed at the sediment-water interface. Bags representing sterile controls, unsterile uninoculated controls, autoclaved inoculated sediment, and unsterile inoculated sediment were studied during a 5-day period for each sediment type. Daily most-probable-number determinations indicated that E. coli populations in unsterile inoculated sediment fluctuated between 5.3 X 10(2) and 2.2 X 10(3) bacteria per g of silty clay and between 3.0 X 10(3) and 1.4 X 10(4) bacteria per g of sand. Autoclaved silty clay sediment inoculated with 1.0 X 10(6) bacteria per g increased to 2.2 X 10(8) bacteria per g in 3 days. During the same period, autoclaved sand sediment inoculated with 1.2 X 10(5) cells per g increased to 5.4 X 10(7) bacteria per g. By day 5, populations in both cultures had decreased by 1 log. The ability of E. coli to survive for several days in aquatic sediment in situ suggests that fecal coliforms in water may not always indicate recent fecal contamination of that water but rather resuspension of viable sediment-bound bacteria. PMID:7041822

  20. Sterols of a contemporary lacustrine sediment. [in English postglacial lake

    NASA Technical Reports Server (NTRS)

    Gaskell, S. J.; Eglinton, G.

    1976-01-01

    Results are reported for detailed sterol analyses of several depths (corresponding to between zero and about 150 yr in age) in a contemporary lacustrine sediment from a freshwater lake of postglacial origin in England. Delta 5-, delta 22-, and delta 5,22-sterols are identified along with 5 alpha- and 5 beta-stanols as well as a C26 stanol with a C7 side chain. Solvent extraction yields carbon number distributions for the 5 alpha- and 5 beta-stanol sediment constituents that parallel the corresponding delta 5-sterol distributions. The amounts of 5 alpha-stanols are found to exceed those of 5 beta-stanols in the sediment, and variations in the ratio of 5 alpha- to 5 beta-stanol between sediment samples from similar depths are shown to suggest an inhomogeneity of the sediment. It is found that the sterol composition of sediment cores varies markedly with depth, reflecting both the effects of a sterol hydrogenation process and a changing input to the sediment. It is concluded that C29 sterols, of probable higher-plant origin, predominate at lower sediment depths while C27 sterols, possibly derived from autochthonous sources, are more abundant in the surface sediment.

  1. Hill-slope instability and sediment delivery: discerning geomorphological intensity from a lake sediment sequence.

    NASA Astrophysics Data System (ADS)

    Chiverrell, R. C.; Shen, Zhixiong; Bloemendal, J.

    2009-04-01

    An extensive database of radiocarbon dated alluvial fan and hill-slope gully systems identifies three phases of extensive hill-slope gullying after 2200, between 1250 and 700, and after 500 cal. BP in the uplands of northwest England. Regional pollen records reveal co-incident phases of increased human activity in these uplands, with small scale temporary clearances during the late Bronze Age / early Iron Age and more substantial clearances during the late Iron Age and Romano-British times (2300-1500 cal. BP), and later more substantial woodland clearances from c.1200-900 cal. BP, after which there has been little woodland recovery. This temporal pattern is similar to that in the geomorphology, and suggests that human activity is a critical factor mediating the late Holocene geomorphological record. To assess the linkages between geomorphic activity and adjacent lake basins a record of sediment delivery from a catchment to lake basin is provided by two c. 5.8 m long sediment cores from Crummock Water (NW England). A robust chronology for the sediment record is provided by parallel optical and 14C ages. The lake sediment magnetic and geochemical properties indicate a series of changes in sediment composition during the late Holocene, which correlate well with sediment lithology, water content and weight-loss-on-ignition. A comprehensive grid-based approach characterising the surface soil/sediment magnetic and geochemical properties has enabled a better understanding of source-sink linkages. In the upper 3-2 metres a suite of changes corresponds to the regional onset of human activity after 2000 BC, and particularly to the intensification of human activity at around AD 900. A comparison of the lake sediment magnetic properties and those of the catchment soils shows clear linkages for the period after AD 900. In contrast, detailed magnetic measurements of the early- through mid-Holocene sediments suggest that their magnetic properties are dominated by bacterial

  2. Potential oxygen demand of sediments from Lake Erie

    USGS Publications Warehouse

    Schloesser, D.W.; Stickel, R.G.; Bridgeman, T.B.

    2005-01-01

    Dreissenid mussels (Dreissena polymorpha and D. bugensis) biodeposit large quantities of filtered materials (i.e., feces and pseudofeces) directly on bottom substrates. These biodeposits have the potential to increase oxygen demand in sediments and overlying waters and thus contribute to hypolimnetic anoxia in Lake Erie. We hypothesized that higher potential oxygen demand of sediments would occur in areas near shore than in offshore hypolimnetic waters as a result of biodeposits carried by currents from littoral water where mussels, available foods, and biodeposits may be most abundant. To address this hypothesis, we measured potential oxygen demand (mg O2/L/120 h incubation) at six sites near shore and six sites offshore monthly June to September 2002 and August 2003. In addition, we compared, in post priori hypothesis, seven sites with and five sites without dreissenid mussels. Contrary to our hypotheses, potential oxygen demand was not significantly higher in bottles containing nearshore sediments than offshore sediments. Similarly, potential oxygen demand was not significantly higher at sites with dreissenid mussels than at sites without mussels. Data are consistent with pre-dreissenid studies which show oxygen demand and percent ash-free dry weights of sediments were higher offshore than near shore and ash-free dry weight of sediments decreased June to September. Therefore, the present study provides no evidence that dreissenid mussels have contributed directly-via biodeposition-to increased anoxia observed in Lake Erie in the mid to late 1990s.

  3. Spectral prediction of sediment chemistry in Lake Okeechobee, Florida.

    PubMed

    Vogel, W Justin; Osborne, Todd Z; James, R Thomas; Cohen, Matthew J

    2016-10-01

    High-resolution diffuse reflectance spectra in the visible and near-infrared wavelengths were used to predict chemical properties of sediment samples obtained from Lake Okeechobee (FL, USA). Chemometric models yielded highly effective prediction (relative percent difference (RPD) = SD/RMSE >2) for some sediment properties including total magnesium (Mg), total calcium (Ca), total nitrogen (TN), total carbon (TC), and organic matter content (loss on ignition (LOI)). Predictions for iron (Fe), aluminum (Al), and various forms of phosphorus (total P (TP), HCl-extractable P (HCl-P), and KCl-extractable P (KCl-P)) were also sufficiently accurate (RPD > 1.5) to be considered useful; predictions for other P fractions as well as all pore water properties were poor. Notably, scanning wet sediments resulted in only a 7 % decline in RPD scores. Moreover, interpolation maps based on values predicted from wet sediment spectra captured the same spatial patterns for Ca, Mg, TC, TN, and TP as maps derived directly from wet chemistry, suggesting that field scanning of perpetually saturated sediments may be a viable option for expediting sample analysis and greatly reducing mapping costs. Indeed, the accuracy of spectral model predictions compared favorably with the accuracy of kriging model predictions derived from wet chemistry observations suggesting that, for some analytes, higher density spatial sampling enabled by use of field spectroscopy could increase the geographic accuracy of monitoring for changes in lake sediment chemical properties.

  4. A sediment resuspension and water quality model of Lake Okeechobee

    USGS Publications Warehouse

    James, R.T.; Martin, J.; Wool, T.; Wang, P.-F.

    1997-01-01

    The influence of sediment resuspension on the water quality of shallow lakes is well documented. However, a search of the literature reveals no deterministic mass-balance eutrophication models that explicitly include resuspension. We modified the Lake Okeeehobee water quality model - which uses the Water Analysis Simulation Package (WASP) to simulate algal dynamics and phosphorus, nitrogen, and oxygen cycles - to include inorganic suspended solids and algorithms that: (1) define changes in depth with changes in volume; (2) compute sediment resuspension based on bottom shear stress; (3) compute partition coefficients for ammonia and ortho-phosphorus to solids; and (4) relate light attenuation to solids concentrations. The model calibration and validation were successful with the exception of dissolved inorganic nitrogen species which did not correspond well to observed data in the validation phase. This could be attributed to an inaccurate formulation of algal nitrogen preference and/or the absence of nitrogen fixation in the model. The model correctly predicted that the lake is lightlimited from resuspended solids, and algae are primarily nitrogen limited. The model simulation suggested that biological fluxes greatly exceed external loads of dissolved nutrients; and sedimentwater interactions of organic nitrogen and phosphorus far exceed external loads. A sensitivity analysis demonstrated that parameters affecting resuspension, settling, sediment nutrient and solids concentrations, mineralization, algal productivity, and algal stoichiometry are factors requiring further study to improve our understanding of the Lake Okeechobee ecosystem.

  5. Improved understanding of Diatom stratigraphy in a varved sediment through lake monitoring and sediment trap data

    NASA Astrophysics Data System (ADS)

    Maier, Dominique Beatrice; Bigler, Christian

    2016-04-01

    Biological remains in lake sediments reflect past conditions in the lake itself and within its catchment. However, it is difficult to disentangle to which extent the environmental drivers are natural (e.g. population dynamics, climate) or human-induced (e.g. agriculture, forestry). Therefore, comprehensive lake monitoring is crucial to understand taphonomy and sediment formation, and enhances the value of the paleolimnological archive. In this study, we analyze survey data of a varved lake in northern Sweden (Nylandssjön, Nordingrå) with special focus on the diatom record. Different monitoring components are combined, i.e. (1) bi-weekly data of chemical parameters (chlorophyll a, nutrients) covering the period from 2012 to 2015, (2) physical parameters (temperature, oxygen, ice-cover) covering the period from 2000-2015, (3) high-resolution data from a sequential sediment trap covering the period from 2000-2015 and (4) annually resolved diatom data from the sediment varves. Early and intense spring mixing in 2012 translates into a short but vertically pervasive chlorophyll a band which is simultaneously recorded in the sequential trap with a high diatom peak (500 000 valves cm2 d-1). The years 2013 and 2014 show higher chlorophyll a concentrations in the water column, but diatoms do not form a peak flux (>100 000 diatoms cm2 d-1) at any time in the sediment trap, probably due to stratification patterns. The trap record from 2012 indicates a spring bloom dominating the sediment signal, but this is not repeated in 2013 and 2014. Future analyses will be directed towards linking the monitored in-lake processes to annually or even seasonally resolved environmental characteristics. The multiplicity of potential ecological and environmental drivers led us to reverse our analytical view by starting with the diatom stratigraphy in the varved sediment, continuing through the data from sediment trap and water column into the lake catchment to identify deviations (timing

  6. Sediment Ammonia-Oxidizing Microorganisms in Two Plateau Freshwater Lakes at Different Trophic States.

    PubMed

    Yang, Yuyin; Zhang, Jingxu; Zhao, Qun; Zhou, Qiheng; Li, Ningning; Wang, Yilin; Xie, Shuguang; Liu, Yong

    2016-02-01

    Both ammonia-oxidizing archaea (AOA) and bacteria (AOB) can contribute to ammonia biotransformation in freshwater lake ecosystems. However, the factors shaping the distribution of sediment AOA and AOB in plateau freshwater lake remains unclear. The present study investigated sediment AOA and AOB communities in two freshwater lakes (hypertrophic Dianchi Lake and mesotrophic Erhai Lake) on the Yunnan Plateau (China). A remarkable difference in the abundance, diversity, and composition of sediment AOA and AOB communities was observed between Dianchi Lake and Erhai Lake. AOB usually outnumbered AOA in Dianchi Lake, but AOA showed the dominance in Erhai Lake. Organic matter (OM), total nitrogen (TN), and total phosphorus (TP) might be the key determinants of AOB abundance, while AOA abundance was likely influenced by the ration of OM to TN (C/N). AOA or AOB community structure was found to be relatively similar in the same lake. TN and TP might play important roles in shaping sediment AOA and AOB compositions in Dianchi Lake and Erhai Lake. Moreover, Nitrososphaera-like AOA were detected in Dianchi Lake. Nitrosospira- and Nitrosomonas-like AOB were dominant in Dianchi Lake and Erhai Lake, respectively. Sediment AOA and AOB communities in Dianchi Lake and Erhai Lake were generally regulated by trophic state.

  7. Anaerobic oxidation of methane in sediments of two boreal lakes

    NASA Astrophysics Data System (ADS)

    Rissanen, Antti J.; Karvinen, Anu; Nykänen, Hannu; Mpamah, Promise; Peura, Sari; Tiirola, Marja; Kankaala, Paula

    2014-05-01

    Anaerobic oxidation of methane (AOM) is a considerable sink for methane (CH4) in marine systems, but very little is known about the occurrence and importance of the process in freshwater systems. In addition, much about the microbial communities involved in AOM is unclear. AOM coupled with sulfate reduction is the dominant AOM process in marine systems but the scarce existing data suggest that, in freshwater systems, AOM coupled with reduction of alternative electron acceptors (nitrate/nitrite, manganese, iron) is more important. In this study, potential for AOM coupled with metal reduction was studied in boreal lake sediments. Slurries of sediment samples collected from two sites in southeastern Finland, i.e. from Lake Orivesi, Heposelkä, an vegetated littoral site, dominated by Phragmites australis (Sample Sa, sediment layer 0 - 25 cm) and from the profundal zone of a mesotrophic Lake Ätäskö (Aa, 0 - 10 cm; Ab, 10 - 30 cm; Ac, 90 - 130 cm), were incubated in laboratory in anaerobic conditions at in situ temperatures for up to 5 months. The samples were amended either 1) with 13CH4, 2) 13CH4 + manganese(II) oxide (MnO) or 3) 13CH4 + iron(III) hydroxide (Fe(OH)3), and the processes were measured by following the 13C transfer to the carbon dioxide (CO2) pool and by concentration measurements of CH4 and CO2. Changes in microbial communities were studied from DNA extracted from sediment samples before and after incubation period by next-generation sequencing (Ion Torrent) of polymerase chain reaction (PCR) - amplified bacterial and archaeal 16S rRNA and methyl coenzyme-M reductase gene (mcrA) amplicons. Increase in 13C of CO2 gas confirmed that AOM took place in sediments of both study lakes. In general, 13CO2 - production was significant both at the beginning (0 - 21 days) and at the end (84 - 151 days) of incubation period. Potential AOM rates (calculated based on 13CO2 - production) varied considerably and were much lower in deep sediment (Sample Ac), 0.1 - 0

  8. Sediment deposition in Lake Clarke, Lake Aldred, and Conowingo Reservoir, Pennsylvania and Maryland, 1910-93

    USGS Publications Warehouse

    Reed, Lloyd A.; Hoffman, Scott A.

    1997-01-01

    The Susquehanna River carries a significant amount of the sediment and the nutrient load transported to the Chesapeake Bay. Three large hydroelectric dams are located near the mouth of the Susquehanna River. The three dams and associated reservoirs are Safe Harbor (Lake Clarke) and Holtwood (Lake Aldred) in southern Pennsylvania and Conowingo (Conowingo Reservoir) in northern Maryland. Two of these reservoirs, Lakes Clarke and Aldred, have reached a state of equilibrium with sediment transport in the river. The third, Conowingo Reservoir, continues to accumulate sediment as well as particulate organic nitrogen and particulate phosphorus. Bottom-elevation surveys of Conowingo Reservoir made in 1959, 1990, and 1993 indicate that the reservoir will reach equilibrium with sediment transport of the river during the next 10 to 20 years. Data collected from 1985-89 indicate that the Susquehanna River transports about 1,780 million pounds of sediment, 147 million pounds of nitrogen, and 5.1 million pounds of phosphorus to the Chesapeake Bay during a year of normal streamflow. Once equilibrium is reached in the Conowingo Reservoir, these loads may increase to levels currently transported by the river to the reservoirs, about 6,600 million pounds of sediment, 153 million pounds of nitrogen, and 9.1 million pounds of phosphorus per year. These higher loads may effect progress made on reducing nutrient loads and should be considered when planning future programs.

  9. Environmental Status and geochemical assessment Sediments of Lake Skadar, Montenegro.

    PubMed

    Kastratović, Vlatko; Jaćimović, Željko; Bigović, Miljan; Đurović, Dijana; Krivokapić, Slađana

    2016-08-01

    The environmental mobility and geochemical partitioning of ten metals were examined in sediments collected from the six locations around Lake Skadar in Montenegro. A three-step sequential extraction procedure was used to determine the distribution of the metals in various substrates of lacustrine sediments, and the concentrations were measured in the liquid extract by ICP-OES. The largest portion of the total amount of cadmium, strontium and manganese can be found in sediment bound to the hydrated iron and manganese oxides; cobalt, lead, copper and nickel in the oxidizable fraction and the highest portion of chromium, vanadium and zinc are in the residual fraction. The most mobilized and potentially mobile metals are strontium, cadmium and cobalt while the most immobilized metals are chromium, vanadium and zinc. Based on geochemical parameters, an assessment of sediment contamination by the investigated metals was performed and the results showed potential risks ranging from "no risk" to "low risk" to the environment.

  10. AMS radiocarbon analyses from Lake Baikal, Siberia: Challenges of dating sediments from a large, oligotrophic lake

    USGS Publications Warehouse

    Colman, Steven M.; Jones, Glenn A.; Rubin, M.; King, J.W.; Peck, J.A.; Orem, W.H.

    1996-01-01

    A suite of 146 new accelerator-mass spectrometer (AMS) radiocarbon ages provides the first reliable chronology for late Quaternary sediments in Lake Baikal. In this large, highly oligotrophic lake, biogenic and authigenic carbonate are absent, and plant macrofossils are extremely rare. Total organic carbon is therefore the primary material available for dating. Several problems are associated with the TOC ages. One is the mixture of carbon sources in TOC, not all of which are syndepositional in age. This problem manifests itself in apparent ages for the sediment surface that are greater than zero. However, because most of the organic carbon in Lake Baikal sediments is algal (autochthonous) in origin, this effect is limited to about 1000+500 years, which can be corrected, at least for young deposits. The other major problem with dating Lake Baikal sediments is the very low carbon contents of glacial-age deposits, which makes them extremely susceptible to contamination with modern carbon. This problem can be minimized by careful sampling and handling procedures. The ages show almost an order of magnitude difference in sediment-accumulation rates among different sedimentary environments in Lake Baikal, from about 0.04 mm/year on isolated banks such as Academician Ridge, to nearly 0.3 mm/year in the turbidite depositional areas beneath the deep basin floors, such as the Central Basin. The new AMS ages clearly indicate that the dramatic increase in diatom productivity in the lake, as evidenced by increases in biogenic silica and organic carbon, began about 13 ka, in contrast to previous estimates of 7 ka for the age of this transition. Holocene net sedimentation rates may be less than, equal to, or greater than those in the late Pleistocene, depending on the site. This variability reflects the balance between variable terrigenous sedimentation and increased biogenic sedimentation during interglaciations. The ages reported here, and the temporal and spatial variation in

  11. Calcium Biomineralization in Sediment of Lake Acigol, an Hypersaline Lake in SW Turkey

    NASA Astrophysics Data System (ADS)

    Celik Balci, Nurgul; Menekse, Meryem; Sonmez, Seref; Gul Karaguler, Nevin

    2010-05-01

    The study of biomineralization in (hyper) saline environments is important for two reasons, 1-it can extend our knowledge about the earliest microbial life on Earth which may have been halophilic 2-because of the presence of hypersaline conditions on Mars, the analog environments in Earth may have implications for the possibility of life on Mars. We examine calcium biomineralization in Lake Acigol, a unique hypersaline lake in southwest Turkey by integrating geochemical and microbiological approaches. Lake Acigol is a perennial lake with a maximum salinity of about 200 g/L and covers an area of 55-60 km2and is one of the main salt reservoirs of Turkey. Water, sediment and core samples were taken from the lake and salty ponds around the lake during the field excursion. The water chemistry revealed relatively high Na and SO4 concentrations both in the lake (30 gr/L, 33.36 gr/L), and the ponds (100 mg/L, 123 mg/L). The mineralogical analyses of sediments showed gypsum, halite, carbonate (aragonite, huntite) precipitation in the lake and ponds. We employed culture-dependent (16s rRNA cloning method, enrichment culture), and -independent techniques to study microbial diversity in Lake Aci gol. Sediment samples were used to isolate Halophilic sp. (e.g. salinicoccus roseus , Dunella sp.) under salinities that were similar to those measured in the lake water to further use in the laboratory Ca-precipitation experiments. For the precipitation experiments, liquid and solid culture media with various salinities ( 6-25 %) in addition to one similar to the lake water were prepared. In order to determine effect of Mg2+-Ca2+ molar ratio on mineralogy and the rate of precipitation, media with different Ca2+and Mg2+ concentrations were also prepared. Our preliminary results indicate that the halophilic bacteria play active role in the precipitation of Ca-minerals but the geochemical conditions are clearly influential. The results also point out that in the Lake Aci gol C, N, P, Ca

  12. Geophysical Detection of Biomineralization Within Selenium Contaminated Lake Sediment

    NASA Astrophysics Data System (ADS)

    O'Brien, M.; Ntarlagiannis, D.; Slater, L.; Yee, N.

    2006-05-01

    Geophysical measurements during active selenite reduction were made on lake sediment from Belews Lake in North Carolina that was verified to contain indigenous cultures known to precipitate the metalloid selenium. The sediment was wet-packed into columns with a mixture of Ottawa sand (80% sand, 20% sediment) to facilitate flow through the sediment. Electrical geophysical measurements were continually monitored as a selenite medium flowed through the column. Electrical conductivity of the influent and outflow solutions was also monitored and outflow samples, taken twice a day, were used to determine the selenite concentrations reduced within the column. Within a few days of beginning the experiment, the sediment/sand mixture within the column exhibited widespread red discoloration, confirming the microbial reduction of selenite to elemental selenium within the column. The electrical formation factor exhibited a smooth increase in time that we attribute to the continual precipitation of selenium biominerals. The geophysical dataset provides a novel means to ascertain rates of biomineralization within the column; information that is difficult to extract from aqueous or solid phase chemistry. The geophysical data indicate that most of the microbial activity occurred within the first 5 days of the experiment.

  13. Physicochemical and analytical data for tributary water, lake water, and lake sediment, Lake Arrowhead, Clay and Archer Counties, Texas, 2006

    USGS Publications Warehouse

    Wilson, Jennifer T.; Musgrove, MaryLynn; Haynie, Monti M.; Van Metre, Peter C.

    2008-01-01

    Lake Arrowhead is a reservoir about 24 kilometers southeast of Wichita Falls, Texas, that provides drinking water for the city of Wichita Falls and surrounding areas. The U.S. Geological Survey, in cooperation with the City of Wichita Falls, did a study in 2006 to assess conditions contributing to elevated arsenic concentrations in Lake Arrowhead. This report describes the sampling and analytical methods, quality assurance, and physicochemical and analytical data. Physiochemical properties were measured in and water samples were collected from five tributaries to Lake Arrowhead (Little Wichita River, West Little Post Oak Creek, East Little Post Oak Creek, Deer Creek, and an unnamed tributary) immediately after storms. Lake water measuring and sampling were done approximately monthly from January through September 2006 at three deep-water sites and seasonally, in January and August 2006, at three shallow-water sites. Cores of lake bottom sediment were collected from five sites on August 30, 2006. Arsenic concentrations in tributary water samples ranged from 1.5 to 6.3 and 0.5 to 4.8 micrograms per liter for unfiltered and filtered samples, respectively. The highest arsenic concentrations were in samples collected from the West Little Post Oak Creek sampling site. Physicochemical properties in lake water varied with depth and season. Dissolved arsenite plus arsenate concentrations in lake water samples generally were between 3 and 5 micrograms per liter. Arsenite concentrations typically were below the laboratory reporting level of 0.6 microgram per liter. There were no detections of monomethylarsonate or dimethylarsinate. The concentration of arsenic in lake sediment samples ranged from 4.4 to 11.2 milligrams per kilogram, with a median of 6.4 milligrams per kilogram. The median arsenic concentration of the five top-interval sediment samples was 8.8 milligrams per kilogram, which generally is higher than the concentrations estimated to be on suspended sediment in

  14. Bottom-sediment chemistry in Devil's Lake, northeast North Dakota

    USGS Publications Warehouse

    Komor, S.C.

    1994-01-01

    High magnesium calcite 8 mole percent MgCO3 is the most abundant carbonate at the sediment surface. With increasing depth abundances of high magnesium carbonate decrease and abundances of low magnesium calcite aragonite and dolomite increase. Carbon isotope compositions of bulk carbonates range from δ13C = -0.7 to +0.5%. These values are close to equilibrium with dissolved inorganic carbon in lake water (δ13C = -2%) but far from equilibrium with dissolved inorganic carbon in pore water (δ13C = -16.3- -10/0%). Disequilibrium between pore water and carbonates suggests that the carbonates did not recrystallize substantially in the presence of pore water. Therefore the change of carbonate mineral proportions with depth in the sediments is due mainly to temporal changes in the proportions of endogenic, detrital, and biologic carbonates that were deposited on the lake bottom rather than postdepositional carbonate diagenesis.

  15. Suspended sediment and metals removal from urban runoff by a small lake

    USGS Publications Warehouse

    Striegl, R.G.

    1987-01-01

    A small lake in the Chicago Metropolitan Area was from 91 to 95 percent efficient in removing suspended sediment and from 76 to 94 percent efficient in removing copper, iron, lead, and zinc from urban runoff. Sediments accumulated in the lake in the form of an organic-rich mud at an average rate of 20 millimeters per year; this reduced lake storage and covered potential habitat for aquatic organisms. Copper, lead, and zinc concentrations were closely associated with suspended-sediment concentrations and with silt- and clay-sized fractions of lake sediment. Although concentrations of mercury and cadmium were near detection limits in runoff, measurable concentrations of these metals accumulated in the lake sediments.A small lake in the Chicago Metropolitan Area was from 91 to 95 percent efficient in removing suspended sediment and from 76 to 94 percent efficient in removing copper, iron, lead, and zinc from urban runoff. Sediments accumulated in the lake in the form of an organic-rich mud at an average rate of 20 millimeters per year; this reduced lake storage and covered potential habitat for aquatic organisms. Copper, lead, and zinc concentrations were closely associated with suspended sediment concentrations and with silt- and clay-sized fractions of lake sediment. Although concentrations of mercury and cadmium were near detection limits in runoff, measurable concentrations of these metals accumulated in the lake sediments.

  16. Repeated sedimentation and exposure of glacial Lake Missoula sediments: A lake-level history at Garden Gulch, Montana, USA

    NASA Astrophysics Data System (ADS)

    Smith, Larry N.

    2017-01-01

    Glaciolacustrine sediments record lake transgression, regression, and subaerial modification of the silty lake-bottom of glacial Lake Missoula in the Clark Fork River valley. The sequence preserved at Garden Gulch, MT documents lake-level fluctuations at >65% of its full-pool volume. Twelve sedimentary cycles fine upwards from (1) very fine-grained sandy silt to (2) silt with climbing ripples to (3) rhythmically laminated silt and some clay. The cycles are fine-grained turbidites capped locally by thin layers of angular gravel derived from local bedrock outcrops. The gravels appear to be the toes of mass wasting lobes carried onto the exposed lakebed surface during repeated lake-level lowerings. Periglacial wedges, small rotational faults, involutions, and clastic dikes deform the tops of eleven cycles. The wedges are 10-30 cm wide, penetrate 30-70 cm deep, are spaced <1 m apart, and contain vertically oriented gravel and massive to laminated sediment. Wedges split and taper in plan view. A few thin silt-filled dikes, which branch and taper downwards from wedges, are interpreted as filled frost cracks. One 10-20 cm-wide sand-filled dike protrudes upward from a sand bed; it is interpreted as a liquefaction feature consistent with a filling and draining lake. The deformed cycle tops preserve evidence of periglacial cold, subaerial exposure, seasonal frost heave, and the incipient formation of sorted polygons. The lowest five cycles are thicker and display more periglacial modification at their tops than the upper seven cycles. The Garden Gulch section may represent as few as seven and as many as twelve substantial fillings and partial to complete drainings of glacial Lake Missoula.

  17. Lake Pontchartrain Basin; bottom sediments and related environmental resources

    USGS Publications Warehouse

    Manheim, Frank T.; Hayes, Laura

    2002-01-01

    Lake Pontchartrain, the largest estuary in southern Louisiana, is an important recreational, commercial, and environmental resource for New Orleans and southeastern Louisiana. This publication is part of a 5-year, cooperative program led by the USGS on the geological framework and sedimentary processes of the Lake Pontchartrain Basin. This presentation is divided into two main parts. The scientifc sections include historical information on the area; shipboard, field, and remote-sensing studies; and a comprehensive sediment database with geological and chemical discussions of the region. The multimedia and resources sections include geographic information system (GIS) tools and data, a video demonstrating vibracore sampling techniques in Lake Pontchartrain, and abstracts from four Basics of the Basin symposia.

  18. Radioisotope Concentration in Lake Sediments of Maracaibo, Venezuela

    SciTech Connect

    Salas, A. Rangel; Viloria, T.; Sajo-Bohus, L.; Barros, H.; Greaves, E. D.; Palacios, D.

    2007-10-26

    Maracaibo Lake is one of the most important water basing and oil producing regions in Venezuela. Changes in the local environment have been monitored for chemical pollution in the past. For this study we selected a set of sediment samples collected in the shore and analyzed for its radioisotope content. Results show the gamma emitting isotopes distribution. Isotopes concentrations have been determined within the natural K, Th and U families.

  19. Tectonic and sediment supply control of deep rift lake turbidite systems: Lake Baikal, Russia

    USGS Publications Warehouse

    Nelson, C.H.; Karabanov, E.B.; Colman, Steven M.; Escutia, C.

    1999-01-01

    Tectonically influenced half-graben morphology controls the amount and type of sediment supply and consequent type of late Quaternary turbidite systems developed in the active rift basins of Lake Baikal, Russia. Steep border fault slopes (footwall) on the northwest sides of half-graben basins provide a limited supply of coarser grained clastic material to multiple small fan deltas. These multiple sediment sources in turn laterally feed small (65 km) axially fed elongate mud-rich fans sourced by regional exterior drainage of the Selenga River that supplies large quantities of silt. Basin plain turbidites in the center of the linear basins and axial channels that are controlled by rift-parallel faults are fed from, and interfinger with, aprons and fans. The predictability of the turbidite systems in Lake Baikal provides the best example yet studied of how tectonics and sediment supply interact to control the development of a wide variety of coeval turbidite systems on a single basin floor.

  20. The Importance of Lake Sediments as a Pathway for Microcystin Dynamics in Shallow Eutrophic Lakes

    PubMed Central

    Song, Haihong; Coggins, Liah X.; Reichwaldt, Elke S.; Ghadouani, Anas

    2015-01-01

    Microcystins are toxins produced by cyanobacteria. They occur in aquatic systems across the world and their occurrence is expected to increase in frequency and magnitude. As microcystins are hazardous to humans and animals, it is essential to understand their fate in aquatic systems in order to control health risks. While the occurrence of microcystins in sediments has been widely reported, the factors influencing their occurrence, variability, and spatial distribution are not yet well understood. Especially in shallow lakes, which often develop large cyanobacterial blooms, the spatial variability of toxins in the sediments is a complex interplay between the spatial distribution of toxin producing cyanobacteria, local biological, physical and chemical processes, and the re-distribution of toxins in sediments through wind mixing. In this study, microcystin occurrence in lake sediment, and their relationship with biological and physicochemical variables were investigated in a shallow, eutrophic lake over five months. We found no significant difference in cyanobacterial biomass, temperature, pH, and salinity between the surface water and the water directly overlying the sediment (hereafter ‘overlying water’), indicating that the water column was well mixed. Microcystins were detected in all sediment samples, with concentrations ranging from 0.06 to 0.78 µg equivalent microcystin-LR/g sediments (dry mass). Microcystin concentration and cyanobacterial biomass in the sediment was different between sites in three out of five months, indicating that the spatial distribution was a complex interaction between local and mixing processes. A combination of total microcystins in the water, depth integrated cyanobacterial biomass in the water, cyanobacterial biomass in the sediment, and pH explained only 21.1% of the spatial variability of microcystins in the sediments. A more in-depth analysis that included variables representative of processes on smaller vertical or local

  1. Spatial and Temporal Patterns of Mercury Accumulation in Lacustrine Sediments Across the Laurentian Great Lakes Region

    EPA Science Inventory

    Data from 103 sediment cores from the Great Lakes and inland lakes of the Great Lakes airshed were compiled to examine and provide a synthesis of patterns of historical and recent changes in mercury (Hg) deposition. Limited data from the lower Laurentian Great Lakes shows a lega...

  2. Chronology of sediment deposition in Upper Klamath Lake, Oregon

    USGS Publications Warehouse

    Colman, Steven M.; Bradbury, J.P.; McGeehin, J.P.; Holmes, C.W.; Edginton, D.; Sarna-Wojcicki, A. M.

    2004-01-01

    A combination of tephrochronology and 14C, 210Pb, and 137Cs measurements provides a robust chronology for sedimentation in Upper Klamath Lake during the last 45 000 years. Mixing of surficial sediments and possible mobility of the radio-isotopes limit the usefulness of the 137Cs and 210Pb data, but 210Pb profiles provide reasonable average sediment accumulation rates for the last 100-150 years. Radiocarbon ages near the top of the core are somewhat erratic and are too old, probably as a result of detrital organic carbon, which may have become a more common component in recent times as surrounding marshes were drained. Below the tops of the cores, radiocarbon ages in the center of the basin appear to be about 400 years too old, while those on the margin appear to be accurate, based on comparisons with tephra layers of known age. Taken together, the data can be combined into reasonable age models for each site. Sediments have accumulated at site K1, near the center of the basin, about 2 times faster than at site CM2, on the margin of the lake. The rates are about 0.10 and 0.05 cm/yr, respectively. The chronological data also indicate that accumulation rates were slower during the early to middle Holocene than during the late Holocene, consistent with increasing wetness in the late Holocene.

  3. Ephemerality of discrete methane vents in lake sediments

    USGS Publications Warehouse

    Scandella, Benjamin P.; Pillsbury, Liam; Weber, Thomas; Ruppel, Carolyn D.; Hemond, Harold F.; Juanes, Ruben

    2016-01-01

    Methane is a potent greenhouse gas whose emission from sediments in inland waters and shallow oceans may both contribute to global warming and be exacerbated by it. The fraction of methane emitted by sediments that bypasses dissolution in the water column and reaches the atmosphere as bubbles depends on the mode and spatiotemporal characteristics of venting from the sediments. Earlier studies have concluded that hot spots—persistent, high-flux vents—dominate the regional ebullitive flux from submerged sediments. Here the spatial structure, persistence, and variability in the intensity of methane venting are analyzed using a high-resolution multibeam sonar record acquired at the bottom of a lake during multiple deployments over a 9 month period. We confirm that ebullition is strongly episodic, with distinct regimes of high flux and low flux largely controlled by changes in hydrostatic pressure. Our analysis shows that the spatial pattern of ebullition becomes homogeneous at the sonar's resolution over time scales of hours (for high-flux periods) or days (for low-flux periods), demonstrating that vents are ephemeral rather than persistent, and suggesting that long-term, lake-wide ebullition dynamics may be modeled without resolving the fine-scale spatial structure of venting.

  4. Ephemerality of discrete methane vents in lake sediments

    NASA Astrophysics Data System (ADS)

    Scandella, Benjamin P.; Pillsbury, Liam; Weber, Thomas; Ruppel, Carolyn; Hemond, Harold F.; Juanes, Ruben

    2016-05-01

    Methane is a potent greenhouse gas whose emission from sediments in inland waters and shallow oceans may both contribute to global warming and be exacerbated by it. The fraction of methane emitted by sediments that bypasses dissolution in the water column and reaches the atmosphere as bubbles depends on the mode and spatiotemporal characteristics of venting from the sediments. Earlier studies have concluded that hot spots—persistent, high-flux vents—dominate the regional ebullitive flux from submerged sediments. Here the spatial structure, persistence, and variability in the intensity of methane venting are analyzed using a high-resolution multibeam sonar record acquired at the bottom of a lake during multiple deployments over a 9 month period. We confirm that ebullition is strongly episodic, with distinct regimes of high flux and low flux largely controlled by changes in hydrostatic pressure. Our analysis shows that the spatial pattern of ebullition becomes homogeneous at the sonar's resolution over time scales of hours (for high-flux periods) or days (for low-flux periods), demonstrating that vents are ephemeral rather than persistent, and suggesting that long-term, lake-wide ebullition dynamics may be modeled without resolving the fine-scale spatial structure of venting.

  5. Factors Affecting the Distribution of Perfluorinated Compounds in Sediments from Lake Shihwa, Korea

    EPA Science Inventory

    Perfluorinated compounds (PFCs) are ubiquitously distributed in various environmental media including water, soil, sediment, and biota. PFCs have also been shown to biomagnify in both aquatic and terrestrial environments. Lake Shihwa is an artificial saltwater lake, located on ...

  6. Spectroscopic Study of Sediments from Chapala Lake in Western Mexico

    NASA Astrophysics Data System (ADS)

    Arízaga, G. G. Carbajal; Doumer, M. E.; Lucio, G. Álvarez; Salazar, S. Gómez; Mangrich, A. S.; Huerta, A. García

    2016-11-01

    The first 10 cm of sediment from Lake Chapala, Western Mexico are in constant activity related to the exchange and speciation of metal cations. Samples of this sediment were analyzed in electron paramagnetic resonance (EPR) equipment to study the paramagnetic metals. Assays indicated that only Fe3+ was present in a detectable amount. This cation, along with chemical fractions of sediment obtained by sequential extraction, was analyzed by EPR. The analysis supported by infrared data revealed that Fe3+ was present in diluted and concentrated domains. Easily exchangeable iron was retained by carbonyl groups in organic matter. The carbonate fraction and oxides contained iron in concentrated domains. The alumina-silicate fraction (that resisted the sequential extraction digestions) presented diluted domains of iron in the octahedral alumina sheet along with occlusions of concentrated domains. This last inference was obtained by comparing EPR results against the spectrum of iron in synthetic model clay.

  7. Lake sediments as natural seismographs: Earthquake-related deformations (seismites) in central Canadian lakes

    NASA Astrophysics Data System (ADS)

    Doughty, M.; Eyles, N.; Eyles, C. H.; Wallace, K.; Boyce, J. I.

    2014-11-01

    Central Canada experiences numerous intraplate earthquakes but their recurrence and source areas remain obscure due to shortness of the instrumental and historic records. Unconsolidated fine-grained sediments in lake basins are 'natural seismographs' with the potential to record ancient earthquakes during the last 10,000 years since the retreat of the Laurentide Ice Sheet. Many lake basins are cut into bedrock and are structurally-controlled by the same Precambrian basement structures (shear zones, terrane boundaries and other lineaments) implicated as the source of ongoing mid-plate earthquake activity. A regional seismic sub-bottom profiling of lakes Gull, Muskoka, Joseph, Rousseau, Ontario, Wanapitei, Fairbanks, Vermilion, Nipissing, Georgian Bay, Mazinaw, Simcoe, Timiskaming, Kipawa, Parry Sound and Lake of Bays, encompassing a total of more than 2000 kilometres of high-resolution track line data supplemented by multibeam and sidescan sonar survey records show a consistent sub-bottom stratigraphy of relatively-thick lowermost lateglacial facies composed of interbedded semi-transparent mass flow facies (debrites, slumps) and rhythmically-laminated silty-clays. Mass flows together with cratered ('kettled') lake floors and associated deformations reflect a dynamic ice-contact glaciolacustrine environment. Exceptionally thick mass flow successions in Lake Timiskaming along the floor of the Timiskaming Graben within the seismically-active Western Quebec Seismic Zone (WQSZ), point to a higher frequency of earthquakes and slope failure during deglaciation and rapid glacio-isostatic rebound though faulting continues into the postglacial. Lateglacial faulting, diapiric deformation and slumping of coeval lateglacial sediments is observed in Parry Sound, Lake Muskoka and Lake Joseph, which are all located above prominent Precambrian terrane boundaries. Lateglacial sediments are sharply overlain by relatively-thin rhythmically-laminated and often semi

  8. The Distribution Pattern of Sediment Archaea Community of the Poyang Lake, the Largest Freshwater Lake in China

    PubMed Central

    Ma, Yantian; Liu, Fangpeng; Kong, Zhaoyu; Kou, Wenbo

    2016-01-01

    Archaea plays an important role in the global geobiochemical circulation of various environments. However, much less is known about the ecological role of archaea in freshwater lake sediments. Thus, investigating the structure and diversity of archaea community is vital to understand the metabolic processes in freshwater lake ecosystems. In this study, sediment physicochemical properties were combined with the results from 16S rRNA clone library-sequencing to examine the sediment archaea diversity and the environmental factors driving the sediment archaea community structures. Seven sites were chosen from Poyang Lake, including two sites from the main lake body and five sites from the inflow river estuaries. Our results revealed high diverse archaea community in the sediment of Poyang Lake, including Bathyarchaeota (45.5%), Euryarchaeota (43.1%), Woesearchaeota (3.6%), Pacearchaeota (1.7%), Thaumarchaeota (1.4%), suspended Lokiarchaeota (0.7%), Aigarchaeota (0.2%), and Unclassified Archaea (3.8%). The archaea community compositions differed among sites, and sediment property had considerable influence on archaea community structures and distribution, especially total organic carbon (TOC) and metal lead (Pb) (p < 0.05). This study provides primary profile of sediment archaea distribution in freshwater lakes and helps to deepen our understanding of lake sediment microbes. PMID:28070167

  9. The Distribution Pattern of Sediment Archaea Community of the Poyang Lake, the Largest Freshwater Lake in China.

    PubMed

    Ma, Yantian; Liu, Fangpeng; Kong, Zhaoyu; Yin, Jianhua; Kou, Wenbo; Wu, Lan; Ge, Gang

    2016-01-01

    Archaea plays an important role in the global geobiochemical circulation of various environments. However, much less is known about the ecological role of archaea in freshwater lake sediments. Thus, investigating the structure and diversity of archaea community is vital to understand the metabolic processes in freshwater lake ecosystems. In this study, sediment physicochemical properties were combined with the results from 16S rRNA clone library-sequencing to examine the sediment archaea diversity and the environmental factors driving the sediment archaea community structures. Seven sites were chosen from Poyang Lake, including two sites from the main lake body and five sites from the inflow river estuaries. Our results revealed high diverse archaea community in the sediment of Poyang Lake, including Bathyarchaeota (45.5%), Euryarchaeota (43.1%), Woesearchaeota (3.6%), Pacearchaeota (1.7%), Thaumarchaeota (1.4%), suspended Lokiarchaeota (0.7%), Aigarchaeota (0.2%), and Unclassified Archaea (3.8%). The archaea community compositions differed among sites, and sediment property had considerable influence on archaea community structures and distribution, especially total organic carbon (TOC) and metal lead (Pb) (p < 0.05). This study provides primary profile of sediment archaea distribution in freshwater lakes and helps to deepen our understanding of lake sediment microbes.

  10. Holocene and Late Glacial varved sediments from Czechowskie Lake (Poland)

    NASA Astrophysics Data System (ADS)

    Ott, Florian; Brauer, Achim; Słowiński, Michał; Dulski, Peter; Plessen, Birgit; Blaszkiewicz, Miroslaw

    2013-04-01

    Annual laminated (varved) sediment records are essential for detailed paleoclimate and environmental reconstructions as they function as a natural memory beyond instrumental datasets. In order to determine Holocene inter-annual and decadal-scale variability we investigated varved Lake Czechowskie (53°52' N/ 18°14' E, 108 m asl.), northern Poland. During two coring campaigns in 2009 and 2012 we recovered several long and short cores with the longest core reaching 14.5 m. Based on correlation with a biostratigraphically and tephrochronologically dated neighboring paleolake sediment record (Trzechowskie mire) the record extends back in to the Late Glacial. Lake Czechowskie is well suited for climate reconstruction as varves are almost entirely well (88 %) or poorly (5%) preserved. Only 7 % of the sediment profile are non-varved. Detailed investigations have been carried out for the last 2000 years of the sediment profile applying micro-facies analyses combined with X-ray fluorescence element scanning (µ-XRF) at 200 µm resolution and carbon and nitrogen analyses (TOC, TC, TN) at five-varveresolution. The chronology has been established by a multiple dating approach with 137Cs (for the last ca. 50 years), AMS 14C on plant macro remains (back to 2800 cal BP) and varve counting. Varve formation and preservation ceases at the beginning of the 20th century whereas the younger sediments are again faintly varved. Micro-facies analyses reveal that the sediment consists of biogenic calcite varves with intercalated diatom rich layers. Three distinct 100 to 200 years long periods of up to threefold thicker varves (approx. 1.4 to 5.0 mm/year) are predominantly caused by an increase in the diatom sub-layers and indicate distinct short-term climatic and environmental fluctuations. Possible reasons for these changes that occurred abruptly with only few years are either changes in lake water circulation or in nutrient supply to the lake. This study is a contribution to the Virtual

  11. Geomicrobiological Features of Ferruginous Sediments from Lake Towuti, Indonesia

    PubMed Central

    Vuillemin, Aurèle; Friese, André; Alawi, Mashal; Henny, Cynthia; Nomosatryo, Sulung; Wagner, Dirk; Crowe, Sean A.; Kallmeyer, Jens

    2016-01-01

    Lake Towuti is a tectonic basin, surrounded by ultramafic rocks. Lateritic soils form through weathering and deliver abundant iron (oxy)hydroxides but very little sulfate to the lake and its sediment. To characterize the sediment biogeochemistry, we collected cores at three sites with increasing water depth and decreasing bottom water oxygen concentrations. Microbial cell densities were highest at the shallow site—a feature we attribute to the availability of labile organic matter (OM) and the higher abundance of electron acceptors due to oxic bottom water conditions. At the two other sites, OM degradation and reduction processes below the oxycline led to partial electron acceptor depletion. Genetic information preserved in the sediment as extracellular DNA (eDNA) provided information on aerobic and anaerobic heterotrophs related to Nitrospirae, Chloroflexi, and Thermoplasmatales. These taxa apparently played a significant role in the degradation of sinking OM. However, eDNA concentrations rapidly decreased with core depth. Despite very low sulfate concentrations, sulfate-reducing bacteria were present and viable in sediments at all three sites, as confirmed by measurement of potential sulfate reduction rates. Microbial community fingerprinting supported the presence of taxa related to Deltaproteobacteria and Firmicutes with demonstrated capacity for iron and sulfate reduction. Concomitantly, sequences of Ruminococcaceae, Clostridiales, and Methanomicrobiales indicated potential for fermentative hydrogen and methane production. Such first insights into ferruginous sediments showed that microbial populations perform successive metabolisms related to sulfur, iron, and methane. In theory, iron reduction could reoxidize reduced sulfur compounds and desorb OM from iron minerals to allow remineralization to methane. Overall, we found that biogeochemical processes in the sediments can be linked to redox differences in the bottom waters of the three sites, like oxidant

  12. Eutrophication History of Small Shallow Lakes in Estonia: Evidence from Multiproxy Analysis of Lake Sediments

    NASA Astrophysics Data System (ADS)

    Koff, T.; Marzecova, A.; Vandel, E.; Mikomägi, A.; Avi, E.

    2015-12-01

    Human activities have impacted aquatic systems through the release of contaminants and the regulation of surface and groundwater. Although environmental monitoring has been essential in detecting eutrophication, biodiversity loss or water quality deterioration, monitoring activities are limited in time and are thus not sufficient in their scope to identify causality and thresholds. Paleolimnological studies increasingly show that the response of lakes to climatic and human influences is complex, multidimensional, and often indirectly mediated through watershed processes. In this study we examine the history of eutrophication processes in small lakes in Estonia using the multi-proxy analysis of sediment. Study sites represent lakes with different anthropogenic stressors: urbanisation and recreational use, run-off from an oil shale mine, and fish-kills and liming measures. We have used diverse analytical methods, such as elemental analysis, stable isotopes, fossil pigments, diatoms and Cladocera remains. The information derived from sedimentary indicators broadly agrees with the historical evidence of eutrophication and pollution. Moreover, the sediment records are indispensable for identifying additional issues such as: 1) earlier onset of cultural eutrophication; 2) the significant impact of catchment erosion on the deterioration of lake quality, particularly cyanobacterial blooms; and 3) changes in sedimentation processes with significance for internal biogeochemical cycling of nutrients. Importantly, the integration of several methods has significantly improved interpretation of sedimentary data and elucidated the different strengths of various indicator types. The project findings prove to be highly relevant for both the prediction of the ecological responses of lakes to different anthropogenic impacts and the establishment of reasonable reference target conditions in restoration schemes, as well as for methodological improvements of the sediment analysis.

  13. Detecting Magnetosomes in Freshwater Lakes and Lake Sediments: A comparison of techniques

    NASA Astrophysics Data System (ADS)

    Kodama, K. P.; Kim, B.; Kopp, R.; Chen, A. P.

    2008-12-01

    We will present a summary of the work done to date on detecting magnetosomes in the lake sediments and water column of Lake Ely, a small post-glacial lake in northeastern Pennsylvania. To establish that magnetosomes dominate the magnetic mineralogy of the Lake Ely sediments we sampled the water column every meter down to its maximum depth of 23 m and measured the dissolved oxygen, sulfide, and iron, as well as the ARM of the material filtered from the water. We examined the water samples for magnetotactic bacteria. These results established an increase in the ARM of the filtered material at the oxic-anoxic transition. They also showed that the ARM was carried by magnetosomes produced by magnetotactic bacteria living in the water column at depths from 15-19 m. TEM of magnetic separates collected from the lake sediments show that magnetosomes are transferred to the sediments from the water column and are a significant fraction of the magnetic minerals in the sediments. We used a variety of mineral magnetic techniques to magnetically characterize the magnetosomes in the lake sediments. The delta-delta ratio test of low temperature behavior at the Verwey transition (Moskowitz et al., 1993) gave values of 1.2 to 1.5, lower than the theoretically predicted level of 2 for magnetosomes, but a numeric unmixing technique could resolve higher delta-delta ratios in the dark organic-rich layers in the sediments where magnetosomes were more prevalent. ARM/SIRM ratios of 0.15 to 0.35 with Raf values (the crossover of an IRM acquisition curve versus its alternating field demagnetization curve) of 0.45 to 0.5 are consistent with the presence of magnetosomes in the sediments, the water column, and in a sediment trap located at the bottom of the lake. IRM and ARM acquisition modeling of samples collected from a 160 cm piston core revealed two components of magnetization with coercivities of about 25 mT and 65 mT that are identified as Egli's (2004) biogenic soft (BS) and biogenic

  14. Lake-bottom sediment composition for the assessment of ecological state of West Siberian oil fields

    NASA Astrophysics Data System (ADS)

    Krasnoyarova, N. A.; Russkikh, I. V.; Strel'nikova, E. B.

    2016-11-01

    The paper presents research findings on the oil composition of Fedorovskoe and Nivagal'skoe, Nizhnevartovskoe and Samotlorskoe (Khanty-Mansi Autonomous Okrug), Verkhtarskoe (Novosibirsk region) fields and also the organic components of bottom sediments of Vachlor, Dolgoe, and Balman Lakes. A comparison is given for hydrocarbon composition in bituminous components of lake-bottom sediments and nearby oil fields. The contribution of crude oils to the organic composition of bottom sediments of Vachlor and Balman Lakes is studied in this paper.

  15. Rockmagnetism and inorganic geochemistry of Grand Lake sediment, NE Russia

    NASA Astrophysics Data System (ADS)

    Minyuk, P. S.; Borkhodoev, V. Y.; Subbotnikova, T. V.

    2013-12-01

    Grand Lake, located in Magadan region (51 53'E, 60 44'N), belongs to the group of Elikchan Lakes. Maximum depth of the lake is 23.2 m. 12 cores from deep and shallow parts of the lake were taken using a Livingston corer. Sediment records from Grand Lake provide a continuous archive of climate change during marine isotopic stages (MIS) 4-1. Magnetic susceptibility (MS), saturation magnetization, saturation remanence, coercive force, remanence coercivity, temperature dependence of the induced magnetization and susceptibility of sediment and magnetic extracts were analyzed. Scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX) was used to diagnose Fe-bearing minerals. MS from cores was used for correlation between the core sections. Analysis of the complex data indicate that there are four main lithologic units of sediment. Unit 1 (MIS 1), depth 0-320 cm. Upper subunit (0-150 cm) shows negative or very low MS. Sediment has high content of organic matter and SiO2 (up to 92%) because of biogenic component. The Lower subunit (depth 150-320 cm) consists of laminated organic silt. The MS of this subunit ranges from 0 to 295 (95), 10-6 SI. The sediment shows high content of Fe2O3, P2O5, MnO indicating a redox boundary. Unit 2 (MIS 2), depth 320-627 cm. Sediment is composed of laminated silt and formed during anoxic conditions. Dark thin layers are enriched with P2O5 and MnO. The unit is characterized by low MS = 57-500 (170), 10-6, SI. Vivianite and Fe-sulfides including pyrite and greigite are found in this unit. Greigite occurs in diatom valves and as fine grained aggregates and has specific thermomagnetic curves. Unit 3 (MIS 3), depth 627-965 cm. Sediment consist of homogenous silt and that accumulated during oxic conditions. Unit has highest MS in the core section: 87-1300 (480), 10-6 SI and is enriched with CaO, Na2O, K2O, SiO2. Unite 4 (MIS 4), depth-965-1015 cm includes sand, dense silt and shows high variations of MS values. According to

  16. Are lake sediments mere archives of degraded organic matter? - evidence of rapid biotic changes tracked in sediments of pre-alpine Lake Lunz, Austria

    NASA Astrophysics Data System (ADS)

    Hollaus, Lisa-Maria; Khan, Samiullah; Schelker, Jakob; Ejarque, Elisabet; Battin, Tom; Kainz, Martin

    2016-04-01

    Lake sediments are used as sentinels of changes in organic matter composition and dynamics within lakes and their catchments. In an effort to investigate how past and recent hydrological extreme events have affected organic matter composition in lake sediments, we investigated the biogeochemical composition of sediment cores and settling particles, using sediment traps in the pre-alpine, oligotrophic Lake Lunz, Austria. We assessed annual sedimentation rates using 137Cs and 210Pb, time integrated loads of settling particles, analyze stable carbon (δ13C) and nitrogen (δ15N) isotopes to track changes of carbon sources and trophic compositions, respectively, and use source-specific fatty acids as indicators of allochthonous, bacterial, and algal-derived organic matter. Preliminary results indicate that settling particles of Lake Lunz (33 m depth) contain high algae-derived organic matter, as assessed by long-chain polyunsaturated fatty acids (LC-PUFA), indicating low degradation of such labile organic matter within the water column of this lake. However, LC-PUFA decreased rapidly in sediment cores below the sediment-water interface. Concentrations of phosphorous remained stable throughout the sediment cores (40 cm), suggesting that past changes in climatic forcing did not alter the load of this limiting nutrient in lakes. Ongoing work reveals dramatic biotic changes within the top layers of the sediment cores as evidenced by high numbers of small-bodied cladocerans (e.g., Bosmina) and large-bodied zooplankton (e.g., Daphnia) are only detected at lower sediment layers. Current research on these lake sediments is aimed at investigating how organic matter sources changed during the past century as a result of recorded weather changes.

  17. Sediment deposition and selected water-quality characteristics in Cedar Lake and Lake Olathe, Northeast Kansas, 2000

    USGS Publications Warehouse

    Mau, D.P.

    2002-01-01

    The Lake Olathe watershed, located in northeast Kansas, was investigated using bathymetric survey data and reservoir bottom-sediment cores to determine sediment deposition, water-quality trends, and transport of nutrients (phosphorus and nitrogen species), selected trace elements, selected pesticides, and diatoms as indicators of eutrophic (organic-enriched and depleted oxygen supply) conditions. To determine sediment deposition and loads, bathymetric data from Cedar Lake and Lake Olathe, both located in the Lake Olathe watershed, were collected in 2000 and compared to historical topographic data collected when the lakes were built. Approximately 338 acre-feet of sediment deposition has occurred in Cedar Lake since dam closure in 1938, and 317 acre-feet has occurred at Lake Olathe since 1956. Mean annual sediment deposition was 5.45 acre-feet per year (0.89 acre-feet per year per square mile) for Cedar Lake and 7.0 acre-feet per year (0.42 acre-feet per year per square mile) for Lake Olathe. Mean annual sediment loads for the two reservoirs were 9.6 million pounds per year for Cedar Lake and 12.6 million pounds per year for Lake Olathe. Mean concentrations of total phosphorus in bottom-sediment samples from Cedar Lake ranged from 1,370 to 1,810 milligrams per kilogram, and concentrations in bottom-sediment samples from Lake Olathe ranged from 588 to 1,030 milligrams per kilogram. The implication of large total phosphorus concentrations in the bottom sediment of Cedar Lake is that inflow into Cedar Lake is rich in phosphorus and that adverse water-quality conditions could affect water quality in downstream Lake Olathe through discharge of water from Cedar Lake to Lake Olathe via Cedar Creek. Mean annual phosphorus loads transported from the Lake Olathe watershed were estimated to be 14,700 pounds per year for Cedar Lake and 9,720 pounds per year for Lake Olathe. The mean annual phosphorus yields were estimated to be 3.74 pounds per acre per year for Cedar Lake and 0

  18. Lake sediment records on climate change and human activities in the Xingyun Lake catchment, SW China.

    PubMed

    Zhang, Wenxiang; Ming, Qingzhong; Shi, Zhengtao; Chen, Guangjie; Niu, Jie; Lei, Guoliang; Chang, Fengqin; Zhang, Hucai

    2014-01-01

    Sediments from Xinyun Lake in central Yunnan, southwest China, provide a record of environmental history since the Holocene. With the application of multi-proxy indicators (total organic carbon (TOC), total nitrogen (TN), δ13C and δ15N isotopes, C/N ratio, grain size, magnetic susceptibility (MS) and CaCO3 content), as well as accelerator mass spectrometry (AMS) 14C datings, four major climatic stages during the Holocene have been identified in Xingyun's catchment. A marked increase in lacustrine palaeoproductivity occurred from 11.06 to 9.98 cal. ka BP, which likely resulted from an enhanced Asian southwest monsoon and warm-humid climate. Between 9.98 and 5.93 cal. ka BP, a gradually increased lake level might have reached the optimum water depth, causing a marked decline in coverage by aquatic plants and lake productivity of the lake. This was caused by strong Asian southwest monsoon, and coincided with the global Holocene Optimum. During the period of 5.60-1.35 cal. ka BP, it resulted in a warm and dry climate at this stage, which is comparable to the aridification of India during the mid- and late Holocene. The intensifying human activity and land-use in the lake catchment since the early Tang Dynasty (∼1.35 cal. ka BP) were associated with the ancient Dian culture within Xingyun's catchment. The extensive deforestation and development of agriculture in the lake catchment caused heavy soil loss. Our study clearly shows that long-term human activities and land-use change have strongly impacted the evolution of the lake environment and therefore modulated the sediment records of the regional climate in central Yunnan for more than one thousand years.

  19. Lake Sediment Records on Climate Change and Human Activities in the Xingyun Lake Catchment, SW China

    PubMed Central

    Zhang, Wenxiang; Ming, Qingzhong; Shi, Zhengtao; Chen, Guangjie; Niu, Jie; Lei, Guoliang; Chang, Fengqin; Zhang, Hucai

    2014-01-01

    Sediments from Xinyun Lake in central Yunnan, southwest China, provide a record of environmental history since the Holocene. With the application of multi-proxy indicators (total organic carbon (TOC), total nitrogen (TN), δ13C and δ15N isotopes, C/N ratio, grain size, magnetic susceptibility (MS) and CaCO3 content), as well as accelerator mass spectrometry (AMS) 14C datings, four major climatic stages during the Holocene have been identified in Xingyun′s catchment. A marked increase in lacustrine palaeoproductivity occurred from 11.06 to 9.98 cal. ka BP, which likely resulted from an enhanced Asian southwest monsoon and warm-humid climate. Between 9.98 and 5.93 cal. ka BP, a gradually increased lake level might have reached the optimum water depth, causing a marked decline in coverage by aquatic plants and lake productivity of the lake. This was caused by strong Asian southwest monsoon, and coincided with the global Holocene Optimum. During the period of 5.60–1.35 cal. ka BP, it resulted in a warm and dry climate at this stage, which is comparable to the aridification of India during the mid- and late Holocene. The intensifying human activity and land-use in the lake catchment since the early Tang Dynasty (∼1.35 cal. ka BP) were associated with the ancient Dian culture within Xingyun’s catchment. The extensive deforestation and development of agriculture in the lake catchment caused heavy soil loss. Our study clearly shows that long-term human activities and land-use change have strongly impacted the evolution of the lake environment and therefore modulated the sediment records of the regional climate in central Yunnan for more than one thousand years. PMID:25033404

  20. Spatiotemporal variation of planktonic and sediment bacterial assemblages in two plateau freshwater lakes at different trophic status.

    PubMed

    Dai, Yu; Yang, Yuyin; Wu, Zhen; Feng, Qiuyuan; Xie, Shuguang; Liu, Yong

    2016-05-01

    Both planktonic and sediment bacterial assemblages are the important components of freshwater lake ecosystems. However, their spatiotemporal shift and the driving forces remain still elusive. Eutrotrophic Dianchi Lake and mesotrophic Erhai Lake are the largest two freshwater lakes on the Yunnan Plateau (southwestern China). The present study investigated the spatiotemporal shift in both planktonic and sediment bacterial populations in these two plateau freshwater lakes at different trophic status. For either lake, both water and sediment samples were collected from six sampling locations in spring and summer. Bacterioplankton community abundance in Dianchi Lake generally far outnumbered that in Erhai Lake. Sediment bacterial communities in Erhai Lake were found to have higher richness and diversity than those in Dianchi Lake. Sediments had higher bacterial community richness and diversity than waters. The change patterns for both planktonic and sediment bacterial communities were lake-specific and season-specific. Either planktonic or sediment bacterial community structure showed a distinct difference between in Dianchi Lake and in Erhai Lake, and an evident structure difference was also found between planktonic and sediment bacterial communities in either of these two lakes. Planktonic bacterial communities in both Dianchi Lake and Erhai Lake mainly included Proteobacteria (mainly Alpha-, Beta-, and Gammaproteobacteria), Bacteroidetes, Actinobacteria, Cyanobacteria, and Firmicutes, while sediment bacterial communities were mainly represented by Proteobacteria (mainly Beta- and Deltaproteobacteria), Bacteroidetes, Chlorobi, Nitrospirae, Acidobacteria, and Chloroflexi. Trophic status could play important roles in shaping both planktonic and sediment bacterial communities in freshwater lakes.

  1. Anaerobic Oxidation of Methane in Sediments of Two Boreal Lakes

    NASA Astrophysics Data System (ADS)

    Tiirola, M. A.; Rissanen, A. J.; Karvinen, A.; Nykänen, H.; Mpamah, P.; Peura, S.; Kankaala, P.

    2014-12-01

    In this study, potential for Anaerobic oxidation of methane (AOM) coupled with metal reduction was studied in boreal lake sediments. Slurries of sediment samples collected from two sites in southeastern Finland, i.e. from Lake Orivesi, Heposelkä, an vegetated littoral site, dominated by Phragmites australis (Sample Sa, sediment layer 0 - 25 cm) and from the profundal zone of a mesotrophic Lake Ätäskö (Aa, 0 - 10 cm; Ab, 10 - 30 cm; Ac, 90 - 130 cm), were incubated in laboratory in anaerobic conditions at in situ temperatures for up to 5 months. The samples were amended either 1) with 13CH4, 2) 13CH4 + manganese(IV) oxide (MnO2) or 3) 13CH4 + iron(III) hydroxide (Fe(OH)3), and the processes were measured by following the 13C transfer to the carbon dioxide (CO2) pool and by concentration measurements of CH4 and CO2. Changes in microbial communities were studied from DNA extracted from sediment samples before and after incubation period by next-generation sequencing (Ion Torrent) of polymerase chain reaction (PCR) - amplified bacterial and archaeal 16S rRNA and methyl coenzyme-M reductase gene (mcrA) amplicons. AOM took place in every sample except in deepest sample (Ac) with potential rates up to 2.1 nmol CH4 d-1 g-1wetsedim (~2 nmol d-1 cm-3) which are considerably lower than previously reported metal-driven AOM in marine sediments (10-40 nmol d-1 cm-3) but within a range of NO3- -driven AOM in an oligotrophic lake (0.6-3.6 nmol d-1 cm-3). AOM took place without metal additions but addition of Mn4+ increased the potential rates and this increase was especially high in 10-30 cm layer (Ab) of the profundal site (5-fold increase). The structure of the bacterial and archaeal communities changed considerably during incubation. Communities incubated with Mn4+ were especially different from those incubated with Fe3+ or without metals which were more similar with each other. Surprisingly, anaerobic methanotrophic archaea detected, ANME-2D and AOM-associated archaea (AAA

  2. Lake sediment records as earthquake catalogues: A compilation from Swiss lakes - Limitations and possibilities

    NASA Astrophysics Data System (ADS)

    Kremer, Katrina; Reusch, Anna; Wirth, Stefanie B.; Anselmetti, Flavio S.; Girardclos, Stéphanie; Strasser, Michael

    2016-04-01

    Intraplate settings are characterized by low deformation rates and recurrence intervals of strong earthquakes that often exceed the time span covered by instrumental records. Switzerland, as an example for such settings, shows a low instrumentally recorded seismicity, in contrast to strong earthquakes (e.g. 1356 Basel earthquake, Mw=6.6 and 1601 Unterwalden earthquake, Mw=5.9) mentioned in the historical archives. As such long recurrence rates do not allow for instrumental identification of earthquake sources of these strong events, and as intense geomorphologic alterations prevent preservation of surface expressions of faults, the knowledge of active faults is very limited. Lake sediments are sensitive to seismic shaking and thus, can be used to extend the regional earthquake catalogue if the sedimentary deposits or deformation structures can be linked to an earthquake. Single lake records allow estimating local intensities of shaking while multiple lake records can furthermore be used to compare temporal and spatial distribution of earthquakes. In this study, we compile a large dataset of dated sedimentary event deposits recorded in Swiss lakes available from peer-reviewed publications and unpublished master theses. We combine these data in order to detect large prehistoric regional earthquake events or periods of intense shaking that might have affected multiple lake settings. In a second step, using empirical seismic attenuation equations, we test if lake records can be used to reconstruct magnitudes and epicentres of identified earthquakes.

  3. A preliminary magnetic study of Sawa lake sediments, Southern Iraq

    NASA Astrophysics Data System (ADS)

    Ameen, Nawrass

    2016-04-01

    A preliminary magnetic study combined with chemical analyses was carried out in Sawa Lake in Al-Muthanna province, southern Iraq, about 22 km south west of Samawa city (31°18'48.80"N, 45°0'25.25"E). The lake is about 4.74 km length, 1.75 km width and 5.5 m height, it is surrounded by a salt rim which is higher than the lake water by about 2.8 m and sea water by about 18.5 m (Naqash et al., 1977 in Hassan, 2007). The lake is an elongated closed basin with no surface water available to it, it may be fed by groundwater of the Euphrates and Dammam aquifers through system of joints and cracks. This study aims to investigate the concentrations of selected heavy metals as pollutants and magnetic susceptibility (MS) and other magnetic properties of sediment samples from fifty sites collected from the bottom of the lake, the study area lies in an industrial area. The results show spatial variations of MS with mean value of about 4.58 x 10-8 m3 kg-1. Scanning electron microscopy and magnetic mineralogy parameters indicate the dominance of soft magnetic phase like magnetite and presence of hard magnetic phase like hematite. Spatial variations of MS combined with the concentrations of heavy metals suggests the efficiency of magnetic methods as effective, inexpensive and non-time consuming method to outlining the heavy metal pollution. References: Hassan W.F., 2007. The Physio-chemical characteristic of Sawa lake water in Samawa city-Iraq. Marine Mesopotamica, 22(2), 167-179.

  4. A sedimentary facies model for glacial-age sediments in Baldwin Lake, Southern California

    NASA Astrophysics Data System (ADS)

    Blazevic, Michael A.; Kirby, Matthew E.; Woods, Adam D.; Browne, Brandon L.; Bowman, David D.

    2009-07-01

    A combined sedimentological and high-resolution petrographic analysis was conducted on a glacial-age (20,000-65,000 cal yr BP) sediment core from Baldwin Lake, Southern California. The results of this research represent the most complete glacial-age, terrestrial climate record from Southern California to date. These results are used to characterize the different sediment types and to investigate the difference in depositional processes and environments between the core's three predominant sediment types: massive, semi-laminated, and laminated sediments. Massive sediments are commonly associated with a blocky texture and/or desiccation cracks, are organic-poor, have high magnetic susceptibility values, and are coarser-grained. Thin-sections from massive sediments reveal a homogenous sediment fabric. Sub-centimeter-scale laminated and centimeter-scale semi-laminated sediments are generally organic-rich, have low magnetic susceptibility values, and are finer grained. Thin-sections from laminated and semi-laminated sediments reveal diffuse sub-millimeter- to millimeter-scale laminae. This combination of sedimentological and high-resolution petrographic data enabled us to characterize four sediment facies, each related to specific depositional processes and environments: (1) a playa lake; (2) a perennial shallow lake; (3) an intermediate lake with variable lake level; and, (4) a perennial deep lake. At centennial-to millennial-timescales, lower lake levels are represented by deposition of massive to semi-laminated sediments in a playa to a perennial shallow lake environment. At similar timescales, higher lake levels are recorded by semi-laminated to laminated sediments deposited in an intermediate lake to a perennial deep lake environment. These results provide an additional sedimentological study for comparison to similar arid environment basins, and for comparison to existing regional paleoclimatic reconstructions.

  5. Use of hydroacoustic measurements to characterize bottom sediments and guide sampling and remediation of organic contaminants in lake sediments.

    PubMed

    Anderson, Michael A; Conkle, Jeremy L; Pacheco, Porfirio; Gan, Jay

    2013-08-01

    Sampling of bed sediment for contamination characterization is often limited by the heterogeneity in sediment properties and distribution. In this study, we explored the use of hydroacoustic measurements to characterize sediment properties and guide sediment sampling in a small lake contaminated by organochlorine pesticides (OCPs) and PCBs. A dual frequency hydroacoustic survey was conducted to characterize sediment properties, distribution, and thickness in McGrath Lake, near Ventura, CA. Based upon these results, sediment core samples were collected from 15 sites on the lake, and sectioned into 20 cm intervals for sediment characterization and analysis of OCPs and PCBs. Very high concentrations of total DDT and total chlordane were found in the sediments, with mean values of 919 and 34.9 ng g(-1), respectively. Concentrations of OCPs were highest at 60-80 cm depth near the inflow at the north end of the lake. Total PCB concentrations were much lower (mean concentration of 4.5 ng g(-1)). Using the hydroacoustic and chemical data, it was estimated that nearly 30,000 m(3) of DDT- and chlordane-contaminated sediment (above effects range median values) was present in the uppermost 1.2 m of sediment in the lake. A hydroacoustic survey can be a valuable tool used to delineate sediment distribution in a lake, identify areas with deeper organic sediment where hydrophobic contaminants would likely be found, and guide sampling. Sampling and chemical analyses are nonetheless needed to quantify contaminant levels in bottom sediments. When combined with hydroacoustic measurements, this approach can reasonably estimate the distributions and volumes of contaminated sediment important in the development of remediation strategies.

  6. The importance of catchment vegetation for lake sediment mercury records

    NASA Astrophysics Data System (ADS)

    Rydberg, Johan; Rösch, Manfred; Heinz, Emanuel; Biester, Harald

    2014-05-01

    In this study we have used a long, Holocene, sediment profile from a small headwater lake in Southern Germany to determine how changes in the vegetation affected the sediment accumulation in general and the accumulation of mercury in particular. The sediment samples were analyzed for their content of total mercury, organic matter quality/quantity and geochemical composition, and the vegetation development was determined using pollen analysis. Over the course of the Holocene, two major shifts in vegetation occurred, both coincide with changes in mercury accumulation. The period prior to 9000 BP was dominated by non-forest vegetation (e.g., Corylus avellana), and mercury concentrations around 60 ng g-1 (90 μg m-2 yr-1). About 8500 BP there was a shift to forest vegetation (mainly Quercus robur), which coincides with increases in both mercury concentrations and accumulation rates (115 ng g-1 and 140 μg m-2 yr-1, respectively). This vegetation shift also drastically decreased the influx of mineral particles to the lake, likely because the development of a closed forest decreased soil erosion. During the following 3500 years - when the vegetation remained dominated by Quercus robur - mercury concentrations were stable around 115 ng g-1, while mercury accumulation rates decreased to about 110 μg m-2 yr-1 due to a gradual decrease in sediment accumulation during the latter part of this period. Around 5000 BP there is a second shift in the vegetation as Quercus robur is replaced by Fagus sylvatica and Abies alba as the dominant tree species, and again this shift leads to an increase in both mercury concentrations and mercury accumulation rates (200 ng g-1 and 140 μg m-2 yr-1, respectively). This shows that the vegetation - and not only the concentration of mercury in the atmosphere - has an influence on the amount of mercury that is accumulated in a lake's sediment. Firstly, the vegetation will influence the interception of mercury, and other atmospherically derived

  7. Diversity and Composition of Bacterial Community in Soils and Lake Sediments from an Arctic Lake Area

    PubMed Central

    Wang, Neng Fei; Zhang, Tao; Yang, Xiao; Wang, Shuang; Yu, Yong; Dong, Long Long; Guo, Yu Dong; Ma, Yong Xing; Zang, Jia Ye

    2016-01-01

    This study assessed the diversity and composition of bacterial communities within soils and lake sediments from an Arctic lake area (London Island, Svalbard). A total of 2,987 operational taxonomic units were identified by high-throughput sequencing, targeting bacterial 16S rRNA gene. The samples from four sites (three samples in each site) were significantly different in geochemical properties and bacterial community composition. Proteobacteria and Acidobacteria were abundant phyla in the nine soil samples, whereas Proteobacteria and Bacteroidetes were abundant phyla in the three sediment samples. Furthermore, Actinobacteria, Chlorobi, Chloroflexi, Elusimicrobia, Firmicutes, Gemmatimonadetes, Nitrospirae, Planctomycetes, Proteobacteria significantly varied in their abundance among the four sampling sites. Additionally, members of the dominant genera, such as Clostridium, Luteolibacter, Methylibium, Rhodococcus, and Rhodoplanes, were significantly different in their abundance among the four sampling sites. Besides, distance-based redundancy analysis revealed that pH (p < 0.001), water content (p < 0.01), ammonium nitrogen (NH4+-N, p < 0.01), silicate silicon (SiO42--Si, p < 0.01), nitrite nitrogen (NO2--N, p < 0.05), organic carbon (p < 0.05), and organic nitrogen (p < 0.05) were the most significant factors that correlated with the bacterial community composition. The results suggest soils and sediments from a lake area in the Arctic harbor a high diversity of bacterial communities, which are influenced by many geochemical factors of Arctic environments. PMID:27516761

  8. Numerical Simulation of Sediment-Associated Water Quality Processes for a Mississippi Delta Lake

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Three major sediment-associated processes were presented to describe the effects of sediment on lake water quality processes: the effect of suspended sediment on the light intensity for the growth of phytoplankton (PHYTO), the adsorption–desorption of nutrients by sediment, and the release of nutrie...

  9. Quantifying methane flux from lake sediments using multibeam sonar

    NASA Astrophysics Data System (ADS)

    Scandella, B.; Urban, P.; Delwiche, K.; Greinert, J.; Hemond, H.; Ruppel, C. D.; Juanes, R.

    2013-12-01

    Methane is a potent greenhouse gas, and the production and emission of methane from sediments in wetlands, lakes and rivers both contributes to and may be exacerbated by climate change. In some of these shallow-water settings, methane fluxes may be largely controlled by episodic venting that can be triggered by drops in hydrostatic pressure. Even with better constraints on the mechanisms for gas release, quantifying these fluxes has remained a challenge due to rapid spatiotemporal changes in the patterns of bubble emissions from the sediments. The research presented here uses a fixed-location Imagenex DeltaT 837B multibeam sonar to estimate methane-venting fluxes from organic-rich lake sediments over a large area (~400 m2) and over a multi-season deployment period with unprecedented spatial and temporal resolution. Simpler, single-beam sonar systems have been used in the past to estimate bubble fluxes in a variety of settings. Here we extend this methodology to a multibeam system by means of: (1) detailed calibration of the sonar signal against imposed bubble streams, and (2) validation against an in situ independent record of gas flux captured by overlying bubble traps. The calibrated sonar signals then yield estimates of the methane flux with high spatial resolution (~1 m) and temporal frequency (6 Hz) from a portion of the deepwater basin of Upper Mystic Lake, MA, USA, a temperate eutrophic kettle lake. These results in turn inform mathematical models of methane transport and release from the sediments, which reproduce with high fidelity the ebullitive response to hydrostatic pressure variations. In addition, the detailed information about spatial variability of methane flux derived from sonar records is used to estimate the uncertainty associated with upscaling flux measurements from bubble traps to the scale of the sonar observation area. Taken together, these multibeam sonar measurements and analysis provide a novel quantitative approach for the assessment of

  10. Unravelling Copenhagen's stride into the Anthropocene using lake sediments

    NASA Astrophysics Data System (ADS)

    Schreiber, Norman; Andersen, Thorbjørn J.; Frei, Robert; Ilsøe, Peter; Louchouarn, Patrick; Andersen, Kenneth; Funder, Svend; Rasmussen, Peter; Andresen, Camilla S.; Odgaard, Bent; Kjær, Kurt H.

    2014-05-01

    Industrialization including the effects of expanding energy consumption and metallurgy production as well as population growth and demographic pressure increased heavy-metal pollution loads progressively since the Industrial Revolution. Especially the burning of fossil fuels mobilizes heavy metals like lead and zinc on a large scale. By wet and dry deposition, these loads end up in the aquatic environment where sediments serve as sinks for these contaminations. In this study, we examine the pollution history of Copenhagen, Denmark. A sediment core was retrieved for the lake in the Botanical Gardens in central Copenhagen using a rod-operated piston corer. The water body used to be part of the old town's defence-wall system and was turned into a lake by terrain levelling in the mid 17th century. After initial X-ray fluorescence core scanning, element concentrations were determined using emission spectroscopy. The onset of gyttja accumulation in the lake is assumed to start immediately after the construction of the fortification in approximately AD 1645. An age model representing the last approximately 135 years for the uppermost 60cm was established by lead-210 and cesium-137 dating. The older part was dated via recognition of markedly increased levels of levoglucosan which are interpreted to be linked with recorded fires in Copenhagen. Similarly, two distinct layers interstratify the sediment column and mark pronounced increases of minerogenic material inflow which can be linked to known historical events. Significant pollution load increases are evident from the 1700s along with urban growth and extended combustion of carbon carriers fuels such as wood and coals. However, a more pronounced increase in lead and zinc deposition only begins by the mid-19th century. Maxima for the latter two pollutants are reached in the late 1970s followed by a reduction of emissions in accordance with stricter environmental regulations. Here, especially the phasing-out of tetraethyl

  11. Desorption kinetics of fluoranthene and trifluralin from Lake Huron and Lake Erie, USA, sediments.

    PubMed

    Greenberg, Marc S; Burton, G Allen; Landrum, Peter F; Leppänen, Matti T; Kukkonen, Jussi V K

    2005-01-01

    Desorption kinetics were determined for fluoranthene (FLU) and trifluralin (TF) spiked onto Lake Erie and Lake Huron, USA, sediments at three concentrations (10, 40, 100 mg/kg dry wt). Following four months of equilibration, desorption was measured by extraction with Tenax and the data were fit to a first-order three-compartment kinetic model. The rate constants of the rapidly (k(rap)), slowly (k(slow)), and very slowly (k(vs)) desorbing fractions were on the order of 10(-1)/h, 10(-2-3)/h, and 10(-4)/h, respectively. The t99.9 (time required for 99.9% of the FLU and TF to desorb from each pool value) for each compartment indicated that FLU and TF desorption from rapid, slow, and very slow compartments were on the order of hours, days, and years, respectively. Higher rates of desorption were observed for FLU and TF from the Lake Huron sediments and this was not apparently related to the total organic carbon (TOC), particle size distribution, or polarity (carbon-to-nitrogen ratio) of the sediments. In general, the total fraction of the initial contaminant amounts that desorbed over the time course was directly related to concentration, which we hypothesized was due to the combined effects of saturation of high-energy (slow and very slow) binding sites in the organic carbon matrix and hysteresis. In extrapolations to field conditions, FLU and TF were predicted to persist in the sediments for years due to the very slow desorption of an estimated 31 to 53% of the bulk concentrations. Based on the rapidly desorbing fractions, the bioavailable amounts of the contaminants were predicted to be between 31 to 55% of bulk sediment concentrations.

  12. Mississippi oxbow lake sediment quality during an artificial flood.

    PubMed

    Knight, S S; Lizotte, R E; Moore, M T; Smith, S; Shields, F D

    2009-04-01

    Surface sediment quality was assessed during a 35-day artificial flood in a shallow (<1.5 m) oxbow lake along the Coldwater River, Mississippi, using Hyalella azteca 28-day bioassays. Seventeen pesticides were monitored in sediments before, during and after flooding, with increases in atrazine and metolachlor concentrations coinciding with two unexpected storm events, 51 and 56 mm, during and after flooding, respectively. Mean 28-day H. azteca survival was >85% throughout this study. However, growth was affected at three sites during flooding with limited growth recovery after flooding. Patterns in observed growth impairment were associated with changes in atrazine (R(2)=0.524) and fipronil sulfone (R(2)=0.584) concentrations.

  13. Improving Holocene Climate Reconstructions from Galápagos Lake Sediments: New Insights From Long-Term Lake Monitoring

    NASA Astrophysics Data System (ADS)

    Conroy, J. L.; Thompson, D. M.; Overpeck, J. T.; Bush, M. B.; Cole, J. E.

    2011-12-01

    Lake sediment records from the Galápagos Islands have provided valuable information on Holocene climate variability in the eastern tropical Pacific on interannual to millennial timescales. However, many uncertainties remain, such as the seasonal bias of climate reconstructions, how seasonal and mean state changes relate to changes in interannual climate variability, and the degree of spatial variability within this unique region, where many different ocean currents converge. One key source of these uncertainties is the lack of modern calibration studies between lake sediment variables and instrumental climate data. At present, only one lake sediment record has a quantitative relationship with instrumental climate data, and there has been no long term monitoring of Galápagos lakes to see how they respond to local climate variability, such as El Niño, La Niña, and the seasonal cycle. To improve our understanding of the climatic controls on Galápagos lake sediments, we have embarked on a long-term limnologic monitoring project. Since 2009, we have continuously collected weather data, limnologic measurements and sediment samples from Laguna El Junco, Bainbridge Crater Lake, and Genovesa Crater Lake. Our initial analysis of the first six months of data spanning the 2009-2010 El Niño show that the three lakes responded to warmer temperatures and increased precipitation during the event, which peaked during the warm/wet season in the archipelago. Both Genovesa and Bainbridge Crater Lakes warmed and freshened during peaks in air temperature and precipitation, without substantial changes in lake level. El Junco water temperature peaked several weeks later than water temperature at Genovesa and Bainbridge, and the increase in temperature was accompanied by water column stratification. The moderate El Niño event in 2009-2010 led to the deposition of brown-green, organic-rich sediment in Bainbridge and Genovesa, with minor amounts of authigenic calcium carbonate. Thus

  14. Nearshore versus offshore copper loading in Lake Superior sediments: Implications for transport and cycling

    USGS Publications Warehouse

    Kolak, J.J.; Long, D.T.; Kerfoot, W.C.; Beals, T.M.; Eisenreich, Steven J.

    1999-01-01

    A thorough understanding of the fate and transport of metals in Lake Superior is necessary in order to predict the ability of Lake Superior to recover from anthropogenic perturbations (copper mining). Sediment cores were collected from nearshore and offshore sites in Lake Superior and used to evaluate spatial and temporal variations in copper loading associated with mining-related activities. Although both settings have been strongly affected by anthropogenic releases of copper, copper concentrations in nearshore cores are significantly greater than those found in offshore cores, implying that nearshore copper loading is dominated by simple deposition and burial of sediment generated from mining activities. Temporal variations in copper profiles in sediments from nearshore environments closely mimic copper production rates. Conversely, copper loading histories derived from offshore sediments are not well correlated to production rates. The offshore sediment cores, when compared with analogous cores from Lakes Ontario and Michigan, show that the average, lake-wide intensity of copper loading in Lake Superior is comparable to the other two lakes, despite the fact that Lake Superior has received the largest total burden of anthropogenic copper. Cu/Zn ratios, used to evaluate the amount of copper loading derived from mining discharges, vary strongly in nearshore environments in response to loading. Cu/Zn ratios in offshore sediments are much less variable, implying that copper loading may be regulated by additional mechanisms (solution chemistry and/or biologic uptake). Study of trace metal partitioning within Lake Superior sediments indicates that the organic fraction of the sediment contains the majority of the copper. Copper concentrations in offshore sediments are significantly correlated to organic carbon content of the sediment whereas copper concentrations in nearshore sediments are not. These findings support the model that transport and deposition of particles

  15. Dissimilatory arsenate and sulfate reduction in sediments of two hypersaline, arsenic-rich soda lakes: Mono and Searles Lakes, California.

    PubMed

    Kulp, T R; Hoeft, S E; Miller, L G; Saltikov, C; Murphy, J N; Han, S; Lanoil, B; Oremland, R S

    2006-10-01

    A radioisotope method was devised to study bacterial respiratory reduction of arsenate in sediments. The following two arsenic-rich soda lakes in California were chosen for comparison on the basis of their different salinities: Mono Lake (approximately 90 g/liter) and Searles Lake (approximately 340 g/liter). Profiles of arsenate reduction and sulfate reduction were constructed for both lakes. Reduction of [73As]arsenate occurred at all depth intervals in the cores from Mono Lake (rate constant [k] = 0.103 to 0.04 h(-1)) and Searles Lake (k = 0.012 to 0.002 h(-1)), and the highest activities occurred in the top sections of each core. In contrast, [35S]sulfate reduction was measurable in Mono Lake (k = 7.6 x10(4) to 3.2 x 10(-6) h(-1)) but not in Searles Lake. Sediment DNA was extracted, PCR amplified, and separated by denaturing gradient gel electrophoresis (DGGE) to obtain phylogenetic markers (i.e., 16S rRNA genes) and a partial functional gene for dissimilatory arsenate reduction (arrA). The amplified arrA gene product showed a similar trend in both lakes; the signal was strongest in surface sediments and decreased to undetectable levels deeper in the sediments. More arrA gene signal was observed in Mono Lake and was detectable at a greater depth, despite the higher arsenate reduction activity observed in Searles Lake. A partial sequence (about 900 bp) was obtained for a clone (SLAS-3) that matched the dominant DGGE band found in deeper parts of the Searles Lake sample (below 3 cm), and this clone was found to be closely related to SLAS-1, a novel extremophilic arsenate respirer previously cultivated from Searles Lake.

  16. Dissimilatory arsenate and sulfate reduction in sediments of two hypersaline, arsenic-rich soda lakes: Mono and Searles Lakes, California

    USGS Publications Warehouse

    Kulp, T.R.; Hoeft, S.E.; Miller, L.G.; Saltikov, C.; Murphy, J.N.; Han, S.; Lanoil, B.; Oremland, R.S.

    2006-01-01

    A radioisotope method was devised to study bacterial respiratory reduction of arsenate in sediments. The following two arsenic-rich soda lakes in California were chosen for comparison on the basis of their different salinities: Mono Lake (???90 g/liter) and Searles Lake (???340 g/liter). Profiles of arsenate reduction and sulfate reduction were constructed for both lakes. Reduction of [73As] arsenate occurred at all depth intervals in the cores from Mono Lake (rate constant [k] = 0.103 to 0.04 h-1) and Searles Lake (k = 0.012 to 0.002 h-1), and the highest activities occurred in the top sections of each core. In contrast, [35S] sulfate reduction was measurable in Mono Lake (k = 7.6 ?? 104 to 3.2 ?? 10-6 h-1) but not in Searles Lake. Sediment DNA was extracted, PCR amplified, and separated by denaturing gradient gel electrophoresis (DGGE) to obtain phylogenetic markers (i.e., 16S rRNA genes) and a partial functional gene for dissimilatory arsenate reduction (arrA). The amplified arrA gene product showed a similar trend in both lakes; the signal was strongest in surface sediments and decreased to undetectable levels deeper in the sediments. More arrA gene signal was observed in Mono Lake and was detectable at a greater depth, despite the higher arsenate reduction activity observed in Searles Lake. A partial sequence (about 900 bp) was obtained for a clone (SLAS-3) that matched the dominant DGGE band found in deeper parts of the Searles Lake sample (below 3 cm), and this clone was found to be closely related to SLAS-1, a novel extremophilic arsenate respirer previously cultivated from Searles Lake. Copyright ?? 2006, American Society for Microbiology. All Rights Reserved.

  17. Lake-level history of Lake Michigan for the past 12,000 years: the record from deep lacustrine sediments

    USGS Publications Warehouse

    Colman, Steven M.; Forester, Richard M.; Reynolds, Richard L.; Sweetkind, Donald S.; King, John W.; Gangemi, Paul; Jones, Glenn A.; Keigwin, Loyd D.; Foster, David S.

    1994-01-01

    Collection and analysis of an extensive set of seismic-reflection profiles and cores from southern Lake Michigan have provided new data that document the history of the lake basin for the past 12,000 years. Analyses of the seismic data, together with radiocarbon dating, magnetic, sedimentologic, isotopic, and paleontologic studies of core samples, have allowed us to reconstruct lake-level changes during this recent part of the lake's history.The post-glacial history of lake-level changes in the Lake Michigan basin begins about 11.2 ka with the fall from the high Calumet level, caused by the retreat of the Two Rivers glacier, which had blocked the northern outlet of the lake. This lake-level fall was temporarily reversed by a major influx of water from glacial Lake Agassiz (about 10.6 ka), during which deposition of the distinctive gray Wilmette Bed of the Lake Michigan Formation interrupted deposition of red glaciolacustrine sediment. Lake level then continued to fall, culminating in the opening of the North Bay outlet at about 10.3 ka. During the resulting Chippewa low phase, lake level was about 80 m lower than it is today in the southern basin of Lake Michigan.The rise of the early Holocene lake level, controlled primarily by isostatic rebound of the North Bay outlet, resulted in a prominent, planar, transgressive unconformity that eroded most of the shoreline features below present lake level. Superimposed on this overall rise in lake level, a second influx of water from Lake Agassiz temporarily raised lake levels an unknown amount about 9.1 ka. At about 7 ka, lake level may have fallen below the level of the outlet because of sharply drier climate. Sometime between 6 and 5 ka, the character of the lake changed dramatically, probably due mostly to climatic causes, becoming highly undersaturated with respect to calcium carbonate and returning primary control of lake level to the isostatically rising North Bay outlet. Post-Nipissing (about 5 ka) lake level has

  18. Geomicrobiology of Fe-rich crusts in Lake Superior sediment

    NASA Astrophysics Data System (ADS)

    Dittrich, M.; Monreau, L.; Quazi, S.; Raoof, B.; Chesnyuk, A.; Katsev, S.; Fulthorpe, R.

    2012-04-01

    The limnological puzzles of Lake Superior are increasingly attracting scientists, and very little is known about the sediments and their associated microflora. The sediments are organic poor (less than 5%C) and the lake is deep oligotrophic, with water temperatures at the bottom around 3C. Previous studies reveal Fe-rich layers in the sediments at multiple loccations around the lake. The origin and mechanisms of formation of this layer remain unknown. In this study we investigated geochemical and microbiological processes that may lead to the formation of a two cm thick iron layer about 10 cm below the sediment surface. Sediment cores from two stations (EM, 230m water depth and ED, 310m water depth) in the East Basin were used. We monitored oxygen and pH depth profiles with microsensors, porewater and sediment solid matter were analyzed for nutrient and metal contents. Furthermore, phosphorus and iron sequantial extractions of sediment cores have been perfomed. The total cell count was determined using DAPI epifluoresence microscopy. DNA was extracted from the sediment samples and 16S ribosonal RNA amplicons were analyzed with denaturing gradient gel electrophoresis (DGGE). For a more in depth analysis, DNA samples from 8-10 cm and 10-12 cm were sent to the Research and Testing Lab (Texas) for pyrosequencing of 16S rRNA gene amplicons amplified using barcoded universal primers 27f-519r. The scanning electron microscope (SEM) images from the iron layer 10-12cm show filaments that were encrusted with spheres ca. 20 nm in diameter. SEM observations of thin sections also indicate the presence of very fine particles showing various morphologies. Analyses of the deposit material by SEM and energy dispersive X-ray spectroscopy (EDS) indicate that bacteria cells surfaces served as nucleation surfaces for Fe-oxide formation. EDS line-scans through bacterial cells covered with precipitates reveal phosphorus and carbon peaks at interface between cell surface and Fe

  19. Australian Acid Brine Lake as a Mars Analog: An Analysis of Preserved Lipids in Shore and Lake Sediments

    NASA Astrophysics Data System (ADS)

    Graham, H. V.; Stern, J. C.; Baldridge, A. M.; Thomsen, B. J.

    2016-05-01

    This study investigates organic molecules preserved in sediment cores from an acid brine lake. We explore the distribution and stable isotopic composition of lipids in order to understand preservation potential in similar martian environments.

  20. Characterization of organic phosphorus in lake sediments by sequential fractionation and enzymatic hydrolysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Knowledge of the phosphorus (P) fractions and their bioavailability in sediments is fundamental for understanding the biogeochemical process of P cycle and its role on eutrophication in the lake ecosystems. In this study, 18 surface sediments samples were collected from Dianchi Lake, an eutrophic la...

  1. MERCURY IN SEDIMENTS AND FISH FROM NORTH MISSISSIPPI LAKES AND SUBSEQUENT HUMAN HAZARD EVALUATION

    EPA Science Inventory

    Sediments and/or fish were collected from Sardis, Enid and Grenada Lakes, which are located in three different watersheds in North Mississippi, in order to assess mercury contamination. The mean total mercury concentration in sediments from Enid Lake in 1997 was 0.154 mg Hg/kg, w...

  2. Sediment budget including the role of floodplains: the case of Lake Tana Basin (Ethiopia)

    NASA Astrophysics Data System (ADS)

    Lemma, Hanibal; Admasu, Teshager; Dessie, Mekete; Fentie, Derbew; Poesen, Jean; Lanckriet, Sil; Adgo, Enyew; Nyssen, Jan

    2016-04-01

    Based on the collection of a large new dataset, we quantify the sediment 1) mobilized on the hillslopes surrounding Lake Tana (Ethiopia), 2) stored on the floodplains, 3) transported into the lake, 4) deposited in the lake and 5) delivered out of the lake so as to establish a sediment budget. In 2012 and 2013, suspended sediment concentration (SSC) and discharge measurements were made at 13 monitoring stations, including two lake outlets. 4635 SSC samples were collected and sediment rating curves that account for land cover conditions and rainfall seasonality were established for the 11 river stations, and mean monthly SSC was calculated for the outlets. Effects of the floodplain on rivers' sediment yield (SY) were investigated using the measurements at the upper and lower stations of Gilgel Abay, Gumara, Megech and Rib Rivers. SY from ungauged rivers was assessed using a model that includes catchment area and rainfall, whereas bedload and direct sediment input from lake shores were estimated. As a result, the gross annual SY from both gauged and ungauged rivers, bedload and lake shores was ca. 3.14 million tons, dominantly from Gilgel Abay and Gumara Rivers. The 0.48 million tons sedimentation in floodplains indicate that the floodplains serve as sediment sink. Moreover, annually about 1.09 million tons of sediment leaves the lake through the two outlets. Annual deposition in Lake Tana was about 1.56 million tons with a trapping efficiency of 60%. Furthermore, SSC and SY are generally higher at the beginning of the rainy season because soil in cultivated fields is bare and loose due to frequent ploughing and seedbed preparation. Later on in the season, increased crop and vegetation cover lead to a decrease in sediment supplies. Based on the established sediment budget and its calculated components, one can conclude that the expected lifetime of Lake Tana (20,396 years) is longer than what was anticipated in earlier studies.

  3. Limnological Investigations: Lake Koocanusa, Montana. Part 5. Phosphorus Chemistry of Sediments

    DTIC Science & Technology

    1981-07-01

    these lake sediments; i.e., the eous sediments of Lake Kocanusa , where Ox-Fe variability in CaCO, does not account for any - appears t6 be the...the CRREL SpeciAlReport- series wider the-overall title Limliologicalin- vest igatiohs: Lake Kbocahusa, Moritana; Part 1: Pie-inioibundtnhentstudy: q96...NUMBER V 4 ~Special c’t115 lo iq I 6 IMNOLOGICAL INVESTIGATIONS: LAKE KOOCANUSA,// , ,JONTANA. /’- uS ~ 9~// 7ART 5. PHOSPHORUS CHEMISTRY OF SEDIMENTS

  4. Estimation of Sediment Sources Using Selected Chemical Tracers in the Perry Lake and Lake Wabaunsee Basins, Northeast Kansas

    USGS Publications Warehouse

    Juracek, Kyle E.; Ziegler, Andrew C.

    2007-01-01

    In Kansas and nationally, stream and lake sediment is a primary concern as related to several important issues including water quality and reservoir water-storage capacity. The ability to achieve meaningful decreases in sediment loads to reservoirs requires a determination of the relative importance of sediment sources within the contributing basins. To investigate sources of sediment within the Perry Lake and Lake Wabaunsee Basins of northeast Kansas, representative samples of channel-bank sources, surface-soil sources (cropland and grassland), and reservoir bottom sediment were collected, analyzed, and compared. Subbasins sampled within the Perry Lake Basin included Atchison County Lake, Banner Creek Reservoir, Gregg Creek, Mission Lake, and Walnut Creek. The samples were sieved to isolate the less than 63-micron fraction (that is, the silt and clay) and analyzed for selected nutrients (total nitrogen and total phosphorus), organic and total carbon, 25 trace elements, and the radionuclide cesium-137 (137Cs). To determine which of the 30 constituents provided the best ability to discriminate between channel-bank and surface-soil sources in the two basins, four selection criteria were used. To be selected, it was required that the candidate constituent (1) was detectable, (2) had concentrations or activities that varied substantially and consistently between the sources, (3) had concentration or activity ranges that did not overlap between the sources, and (4) had concentration or activity differences between the sources that were statistically significant. On the basis of the four selection criteria, total nitrogen (TN), total phosphorus (TP), total organic carbon (TOC), and 137Cs were selected. Of the four selected constituents, 137Cs likely is the most reliable indicator of sediment source because it is known to be conservative in the environment. Trace elements were not selected because concentrations in the channel-bank and surface-soil sources generally were

  5. Arsenic, iron and sulfur co-diagenesis in lake sediments

    NASA Astrophysics Data System (ADS)

    Couture, Raoul-Marie; Gobeil, Charles; Tessier, André

    2010-02-01

    Profiles of porewater pH and dissolved As, Fe, Mn, sulfate, total sulfide (ΣS -II), total zero-valent sulfur (ΣS 0), organic carbon and major ion concentrations, as well as those of solid As, acid-volatile sulfide (AVS), total S, Fe, Mn, Al, organic C, 210Pb and 137Cs were determined in the sediment of four lakes spanning a range of redox and geochemical conditions. An inverse modeling approach, based on a one-dimensional transport-reaction equation assuming steady-state, was applied to the porewater As profiles and used to constrain the net rates of reactions involving As ( RnetAs). The model defines depth intervals where As is either released to (positive RnetAs) or removed from (negative RnetAs) the porewaters. At two of the sites, whose bottom water were oxygenated at sampling time, a production zone ( RnetAs = 12 × 10 -18 mol cm -3 s -1-71 × 10 -18 mol cm -3 s -1) is inferred a few cm below the sediment-water interface, coincident with sharp porewater As and Fe peaks that indicate an intense coupled recycling of As and Fe. This process is confirmed by solid As and Fe maxima just below the sediment surface. In these two lakes a zone of As consumption ( RnetAs = -5 × 10 -18 mol cm -3 s -1 to -53 × 10 -18 mol cm -3 s -1), attributed to the slow adsorption of As to authigenic Fe oxyhydroxides, occurs just above the production zone. A second-order rate constant kadsAs of 0.12 ± 0.03 cm 3 mol -1 s -1 is estimated for this adsorption reaction. Such features in the porewater and solid profiles were absent from the two other lakes that develop a seasonally anoxic hypolimnion. Thermodynamic calculations indicate that the porewaters of the four lakes, when sulfidic (i.e., ΣS -II ⩾ 0.1 μM), were undersaturated with respect to all known solid As sulfides; the calculation also predicts the presence of As V oxythioanions in the sulfidic waters, as suggested by a recent study. In the sulfidic waters, the removal of As ( RnetAs = -1 × 10 -18 mol cm -3 s -1 to -23

  6. Bioavailability and preservation of organic phosphorus in freshwater sediments and its role in lake eutrophication

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lake eutrophication in China is a serious environmental concern, especially in lakes from the middle and lower reaches of Yangtze River region and Southwestern China Plateau. The dissolution of organic matter can result in release of phosphorus (P) from lake sediments and organic phosphate (Po) itse...

  7. Assessment of Sediment Measurements in Lake Michigan as a Case Study: Implications for Monitoring and Modeling

    EPA Science Inventory

    Lake Michigan, the sixth largest freshwater lake in the world by surface area, was utilized as a water body for assessment within a case study. Field data collected at 116 sediment sampling sites throughout the lake in an intensive monitoring effort were utilized for assessment ...

  8. Elevated sulfate reduction in metal-contaminated freshwater lake sediments

    SciTech Connect

    Gough, H.L.; Dahl, A.L.; Tribou, E.; Noble, P.A.; Gaillard, J.-F.; Stahl, D.A.

    2009-01-06

    Although sulfate-reducing prokaryotes have long been studied as agents of metals bioremediation, impacts of long-term metals exposure on biologically mediated sulfur cycling in natural systems remains poorly understood. The effects of long-term exposure to metal stress on the freshwater sulfur cycle were studied, with a focus on biologic sulfate reduction using a combination of microbial and chemical methods. To examine the effects after decades of adaptation time, a field-based experiment was conducted using multiple study sites in a natural system historically impacted by a nearby zinc smelter (Lake DePue, Illinois). Rates were highest at the most metals-contaminated sites (-35 {mu}mol/cm{sup 3}/day) and decreased with decreased pore water zinc and arsenic contamination levels, while other environmental characteristics (i.e., pH, nutrient concentrations and physical properties) showed little between-site variation. Correlations were established using an artificial neural network to evaluate potentially non-linear relationships between sulfate reduction rates (SRR) and measured environmental variables. SRR in Lake DePue were up to 50 times higher than rates previously reported for lake sediments and the chemical speciation of Zn was dominated by the presence of ZnS as shown by X-ray Absorption Spectroscopy (XAS). These results suggest that long-term metal stress of natural systems might alter the biogeochemical cycling of sulfur by contributing to higher rates of sulfate reduction.

  9. Distribution of sediment ammonia-oxidizing microorganisms in plateau freshwater lakes.

    PubMed

    Liu, Yong; Zhang, Jingxu; Zhao, Lei; Li, Yuzhao; Dai, Yu; Xie, Shuguang

    2015-05-01

    Both ammonia-oxidizing bacteria (AOB) and archaea (AOA) can play important roles in ammonia biotransformation in ecosystems. However, the factors regulating the distribution of these microorganisms in lacustrine ecosystems remain essentially unclear. The present study investigated the effects of geographic location on the distribution of sediment AOA and AOB in 13 freshwater lakes on the Yunnan Plateau (China). The spatial dissimilarity in the abundance and structure of sediment AOA and AOB communities was observed in these plateau lakes. AOA abundance was usually less than AOB abundance, and the AOA/AOB ratio was positively correlated with water depth. Nitrososphaera-like AOA occurred in most of the studied lakes and were dominant in two lakes. Nitrosospira was the dominant AOB species in most of the lakes, while Nitrosomonas showed high abundance only in three lakes. In addition, geographic location was found to affect lake sediment AOB community structure.

  10. Lake sediment records of industrialization in the Sudbury area of Ontario, Canada

    SciTech Connect

    Huhn, F.J.

    1985-01-01

    The smelting of nickel and copper sulfide ores has drastically modified the original landscape around Sudbury, Ontario. A record of this impact exists in the sediments of local lakes. Changes in the annual fallout of heavy metals, identifiable smoke particulates, and pollen grains reflect the changes that occurred in the sedimentation rate and the vegetation. A year by year chronology for the last 300 years was provided by meromictic lake sediments containing countable seasonal laminations, obtained by a freezing technique that kept the sediments and sediment/water interface undisturbed. Results indicate that: correspondences of vegetation changes, and sedimentation rates with metal residues and smoke particulates in the sediments, and with published smelter records are good; annual laminations in meromictic lakes provided an excellent chronology, as checked against known dates for settlement and the onset of smelting; identifiable smoke particulates provided a good record of smelter activity, and were also a check on metal residue mobility in the sediments.

  11. Heavy metal contamination of sediments in the upper connecting channels of the Great Lakes

    USGS Publications Warehouse

    Nichols, S. Jerrine; Manny, Bruce A.; Schloesser, Donald W.; Edsall, Thomas A.

    1991-01-01

    In 1985, sampling at 250 stations throughout the St. Marys, St. Clair, and Detroit rivers and Lake St. Clair — the connecting channels of the upper Great Lakes — revealed widespread metal contamination of the sediments. Concentrations of cadmium, chromium, copper, lead, mercury, nickel, and zinc each exceeded U.S. Environmental Protection Agency sediment pollution guidelines at one or more stations throughout the study area. Sediments were polluted more frequently by copper, nickel, zinc, and lead than by cadmium, chromium, or mercury. Sediments with the highest concentrations of metals were found (in descending order) in the Detroit River, the St. Marys River, the St. Clair River, and Lake St. Clair. Although metal contamination of sediments was most common and sediment concentrations of metals were generally highest near industrial areas, substantial contamination of sediments by metals was present in sediment deposition areas up to 60 km from any known source of pollution.

  12. Suspended-sediment budget, flow distribution, and lake circulation for the Fox Chain of Lakes in Lake and McHenry Counties, Illinois, 1997-99

    USGS Publications Warehouse

    Schrader, David L.; Holmes, Jr., Robert R.

    2000-01-01

    The Fox Chain of Lakes is a glacial lake system in McHenry and Lake Counties in northern Illinois and southern Wisconsin. Sedimentation and nutrient overloading have occurred in the lake system since the first dam was built (1907) in McHenry to raise water levels in the lake system. Using data collected from December 1, 1997, to June 1, 1999, suspended-sediment budgets were constructed for the most upstream lake in the system, Grass Lake, and for the lakes downstream from Grass Lake. A total of 64,900 tons of suspended sediment entered Grass Lake during the study, whereas a total of 70,600 tons of suspended sediment exited the lake, indicating a net scour of 5,700 tons of sediment. A total of 44,100 tons of suspended sediment was measured exiting the Fox Chain of Lakes at Johnsburg, whereas 85,600 tons entered the system downstream from Grass Lake. These suspended-sediment loads indicate a net deposition of 41,500 tons downstream from Grass Lake, which represents a trapping efficiency of 48.5 percent. A large amount of recreational boating takes place on the Fox Chain of Lakes during summer months, and suspended-sediment load was observed to rise from 110 tons per day to 339 tons per day during the 1999 Memorial Day weekend (May 26 ?31, 1999). Presumably, this rise was the result of the boating traffic because no other hydrologic event is known to have occurred that might have caused the rise. This study covers a relatively short period and may not represent the long-term processes of the Fox Chain of Lakes system, although the sediment transport was probably higher than an average year. The bed sediments found on the bottom of the lakes are composed of mainly fine particles in the silt-clay range. The Grass Lake sediments were characterized as black peat with an organic content of between 9 and 18 percent, and the median particle size ranged from 0.000811 to 0.0013976 inches. Other bed material samples were collected at streamflow-gaging stations on the

  13. Sediment Loading from Crab Creek and Other Sources to Moses Lake, Washington, 2007 and 2008

    USGS Publications Warehouse

    Magirl, Christopher S.; Cox, Stephen E.; Mastin, Mark C.; Huffman, Raegan L.

    2010-01-01

    The average sediment-accumulation rate on the bed of Moses Lake since 1980, based on the identification of Mount St. Helens ash in lakebed cores, was 0.24 inches per year. Summed over the lake surface area, the average sediment-accumulation rate on the lakebed is 190,000 tons per year. Based on USGS stream-gaging station data, the average annual sediment load to Moses Lake from Crab Creek was 32,000 tons per year between 1943 and 2008; the post Mount St. Helens eruption annual load from Crab Creek was calculated to be 13,000 tons per year. The total mass input from Crab Creek and other fluvially derived sediment sources since 1980 has been about 20,000 tons per year. Eolian sediment loading to Moses Lake was about 50,000 tons per year before irrigation and land-use development largely stabilized the Moses Lake dune field. Currently, eolian input to the lake is less than 2,000 tons per year. Considering all sediment sources to the lake, most (from 80 to 90 percent) of post-1980 lakebed-sediment accumulation is from autochthonous, or locally formed, mineral matter, including diatom frustuals and carbonate shells, derived from biogenic production in phytoplankton and zooplankton. Suspended-sediment samples collected from Crab Creek and similar nearby waterways in 2007 and 2008 combined with other USGS data from the region indicated that a proposed Bureau of Reclamation supplemental feed of as much as 650 cubic feet per second through Crab Creek might initially contain a sediment load of as much as 1,500 tons per day. With time, however, this sediment load would decrease to about 10 tons per day in the sediment-supply-limited creek as available sediment in the channel is depleted. Sediment loads in the supplemental feed ultimately would be similar to loads in other bypass canals near Moses Lake. Considering the hydrology and geomorphology of the creek over multiple years, there is little evidence that the proposed supplemental feed would substantially increase the

  14. Comparison of oxygen isotope values from bulk lake sediment and ostracod valves

    NASA Astrophysics Data System (ADS)

    Teng, J.; Blisniuk, P.

    2012-12-01

    The oxygen isotope composition of the water in a lake is largely controlled by the isotopic composition of precipitation in the lake's catchment area, which is, in turn, controlled by a variety of geographic and climatic factors. Accordingly, the potential to reconstruct past isotopic compositions of lake water using authigenic minerals formed in isotopic equilibrium with the lake water makes lake sediments a promising target for paleoclimate reconstructions. Several different materials can be utilized to reconstruct the oxygen isotope composition of paleo-lake water. These include biogenic carbonates, such as shells of macrofossils (e.g., clams and snails), microfossils, (e.g., ostracods) and chemically precipitated carbonates in bulk lake sediment. To evaluate the suitability of different materials for the reconstruction of oxygen isotope values of past precipitation, we compared the oxygen isotope values of bulk lake sediments and ostracod microfossils that were extracted from an 800 meters thick sequence of sediments in the Zada Basin, southwestern Tibet. The sediment was wet-sieved for grain size separation, and the <63 um size fraction was used for the analysis of the bulk lake sediment. The ostracod microfossils were typically separated from the 125-500 um size fraction. Ostracod valves were cleaned using deionized water and ultrasound. When this did not successfully clean them, we used a brush under a microscope. Preliminary results of our work yielded oxygen isotope values of -2 to -22 permil for bulk lake sediment and a narrower range of -4 to -15 permil for ostracod valves (relative to PDB). In some stratigraphic levels, the oxygen isotope values differed by as much as 10 permil. These differences are significantly higher than offsets of several permil which are commonly observed as the result of species specific vital effects during biogenic calcite precipitation. A plausible explanation for this is that the lake sediment contains a significant portion

  15. Influence of geomorphic setting on sedimentation of two adjacent alpine lakes, Triglav Lakes Valley (Julian Alps, NW Slovenia)

    NASA Astrophysics Data System (ADS)

    Smuc, Andrej; Skabene, Dragomir; Muri, Gregor; Vreča, Polona; Jaćimović, Radojko; Čermelj, Branko; Turšič, Janja

    2013-04-01

    The Triglav Lakes Valley is elongated, 7km long depression, located high (at places over 2000 m.a.s.l.) in the central part of the Julian Alps (NW Slovenia). It hosts 6 small isolated lakes that formed due to the combination of Neogene tectonic and Pleistocene glaciation. The study is focused on the 5th and 6th Triglav Valley Lakes that characterize lower part of the valley. The lakes are located so close to each other that they are even connected in times of high water. Thus, they share the same bedrock geology, are subjected to the same climatic forcing and share similar vegetation communities. Despite their proximity, the lakes differ in their hydrologic and geomorphic setting. The lakes have no permanent surface tributaries; however 5th is fed periodically, at times of high water level, by the Močivec spring, while additional water flows from the swamp area near its northern shore. An underground spring on the eastern side of 5th represents the lake's only permanent freshwater inflow, while drainage takes place to the west via a small ponor. 6th has only one weak underground spring on the eastern side of the lake. Water levels may fluctuate between 2 and 3 m. Additionally, the lakes have different configuration of lakes shores; the northern shores of the 5th lake are low-angle soil and debris covered plateau, while southern shores of the 5th lake and shores of the 6th lake are represented by heavily karstified carbonate base rock and covered partly by trees. The detailed sedimentary analysis of the lakes record showed some similarities, but also some significant differences. Sediments of both lakes are represented by fine-grained turbidity current deposits that are transported from lake shores during snow melt or storms. The grain-size and sedimentary rates of the lakes are however markedly different. The 5th lake has coarser grained sediments, with mean ranging from 46 to 60 µm and records higher sedimentation rates of ~0,57 cm/year, compared to the 6th lake

  16. Controlling factors on methanogenesisin the deep sediment of Lake Kinneret

    NASA Astrophysics Data System (ADS)

    Adler, M.; Sivan, O.; Ronen, Z.; Eckert, W.

    2012-04-01

    The main pathways of methane production (methanogenesis) are through fermentation of acetate (acetoclastic methanogenesis) and through CO2 reduction with hydrogen (hydrogenotrophic methanogenesis). In most freshwater environment the dominant pathway is through acetoclastic methanogenesis, while in marine sediments the main pathway is through CO2 reduction. Another minor pathway of methane production is through methylotrophic methanogenesis with noncompetitive substrate like methylamine etc. This study investigates the controlling parameters on methanogenesis in deep lacustrine sediments and their link to methanotrophy process. Our findings suggest that in Lake Kinneret (Israel) sediments (Station A, 38 m depth), methanogenesis is restricted to a zone between 3 and 25 cm depth and ends abruptly. This is based on a model calculation and slurry incubation experiments. Below this zone there is a sink for methane, and sets of geochemical data show that this methane sink is related to anaerobic oxidation of methane (AOM), which is most likely driven by iron reduction rather than sulfate reduction. In order to explore this ending of methanogenesis and its link to the deep AOM; in-situ profiles in the sediments as well as slurry incubation experiments in modified conditions were conducted. Profiles of dissolved organic carbon and acetate show increase in concentrations with depth, suggesting that the ending of methanogenesis is not trivial. Preliminary incubation of sediments from different depths show accumulation of acetate with depth concurrently to lower methane accumulation even with addition of acetate. Considering that the common substrates concentrations increase at this depth, the abrupt absence of methanogenesis is surprising. Different additions to the slurries suggest a link between methane, sulfur and iron at that depth that affects both methanogenesis and the deep AOM process.

  17. Microbial sulfur transformations in sediments from Subglacial Lake Whillans.

    PubMed

    Purcell, Alicia M; Mikucki, Jill A; Achberger, Amanda M; Alekhina, Irina A; Barbante, Carlo; Christner, Brent C; Ghosh, Dhritiman; Michaud, Alexander B; Mitchell, Andrew C; Priscu, John C; Scherer, Reed; Skidmore, Mark L; Vick-Majors, Trista J; The Wissard Science Team

    2014-01-01

    Diverse microbial assemblages inhabit subglacial aquatic environments. While few of these environments have been sampled, data reveal that subglacial organisms gain energy for growth from reduced minerals containing nitrogen, iron, and sulfur. Here we investigate the role of microbially mediated sulfur transformations in sediments from Subglacial Lake Whillans (SLW), Antarctica, by examining key genes involved in dissimilatory sulfur oxidation and reduction. The presence of sulfur transformation genes throughout the top 34 cm of SLW sediments changes with depth. SLW surficial sediments were dominated by genes related to known sulfur-oxidizing chemoautotrophs. Sequences encoding the adenosine-5'-phosphosulfate (APS) reductase gene, involved in both dissimilatory sulfate reduction and sulfur oxidation, were present in all samples and clustered into 16 distinct operational taxonomic units. The majority of APS reductase sequences (74%) clustered with known sulfur oxidizers including those within the "Sideroxydans" and Thiobacillus genera. Reverse-acting dissimilatory sulfite reductase (rDSR) and 16S rRNA gene sequences further support dominance of "Sideroxydans" and Thiobacillus phylotypes in the top 2 cm of SLW sediments. The SLW microbial community has the genetic potential for sulfate reduction which is supported by experimentally measured low rates (1.4 pmol cm(-3)d(-1)) of biologically mediated sulfate reduction and the presence of APS reductase and DSR gene sequences related to Desulfobacteraceae and Desulfotomaculum. Our results also infer the presence of sulfur oxidation, which can be a significant energetic pathway for chemosynthetic biosynthesis in SLW sediments. The water in SLW ultimately flows into the Ross Sea where intermediates from subglacial sulfur transformations can influence the flux of solutes to the Southern Ocean.

  18. Temporal and Spatial Dynamics of Sediment Anaerobic Ammonium Oxidation (Anammox) Bacteria in Freshwater Lakes.

    PubMed

    Yang, Yuyin; Dai, Yu; Li, Ningning; Li, Bingxin; Xie, Shuguang; Liu, Yong

    2017-02-01

    Anaerobic ammonium-oxidizing (anammox) process can play an important role in freshwater nitrogen cycle. However, the distribution of anammox bacteria in freshwater lake and the associated environmental factors remain essentially unclear. The present study investigated the temporal and spatial dynamics of sediment anammox bacterial populations in eutrotrophic Dianchi Lake and mesotrophic Erhai Lake on the Yunnan Plateau (southwestern China). The remarkable spatial change of anammox bacterial abundance was found in Dianchi Lake, while the relatively slight spatial shift occurred in Erhai Lake. Dianchi Lake had greater anammox bacterial abundance than Erhai Lake. In both Dianchi Lake and Erhai Lake, anammox bacteria were much more abundant in summer than in spring. Anammox bacterial community richness, diversity, and structure in these two freshwater lakes were subjected to temporal and spatial variations. Sediment anammox bacterial communities in Dianchi Lake and Erhai Lake were dominated by Candidatus Brocadia and a novel phylotype followed by Candidatus Kuenenia; however, these two lakes had distinct anammox bacterial community structure. In addition, trophic status determined sediment anammox bacterial community structure.

  19. Sedimentological characteristics of lake sediment of the Lake Jelonek (North Poland)

    NASA Astrophysics Data System (ADS)

    Kramkowski, Mateusz; Filbrandt-Czaja, Anna; Ott, Florian; Słowiński, Michał; Tjallingii, Rik; Błaszkiewicz, Mirosław; Brauer, Achim

    2016-04-01

    Lake Jelonek is located in Northern Poland (53°45'58N, 18°23'30E). The lake is surrounded by forest, covers an area of 19,9 ha and has a maximum depth of 13,8 m. In 2013 and 2014 three overlapping and parallel series of long sediment cores JEL14-A-(1445 cm), JEL14-B-(1430 cm), JEL14-C-(1435 cm) and seven short gravity cores JEL13 (K1-K7) have been recovered from the deepest part of the lake. A continuous composite profile JEL14 covering 1426 cm has been established by correlation based on 28 distinct macroscopic marker layers. The sediment sequence can be divided into 15 (I-XV) lithological units. These units comprise biochemical calcite varves, homogeneous calcite-rich gyttja, homogeneous organic-diatomaceous gyttja, and sandy layers. The chronology established so far is based on 14 AMS 14C dates from terrestrial plant remains and tephrochronology (Askja AD-1875) and covers the interval from the Younger Dryas to present times. Based on the chronology and sedimentological characteristics the composite profile has been correlated to a previous core from which a detailed pollen diagram had been established (Filbrandt-Czaja 2009). Here we present initial results from thin section analyses for two intervals from the new composite record JEL14, (I) the uppermost 0-256 cm and (II) the interval from 768-1296 cm. Intercalated between these two varved interval is a thick section (512 cm) of homogeneous organic-ditomaceous sediments. We present varve micro-facies data in combination with μ-XRF element scanning for comprehensive reconstruction of the sedimentation processes in Lake Jelonek. Preliminary varve counting reveals that the uppermost 256 cm varved sediments comprise ca 925 years (2008-1083 AD), while the lower floating varve interval covers the time period from 1850 - 10500 cal a BP. This study is a contribution to the Virtual Institute of Integrated Climate and Landscape Evolution Analysis -ICLEA- of the Helmholtz Association; grant number VH-VI-415. References

  20. Reservoir sedimentation and environmental degradation: assessing trends in sediment-associated trace elements in Grenada Lake, Mississippi.

    PubMed

    Bennett, Sean J; Rhoton, Fred E

    2007-01-01

    Sediments impounded within flood control reservoirs are potentially important archives of environmental and geomorphic processes occurring within drainage basins. The concentrations of select sediment-associated trace elements were assessed within the impoundment of Grenada Lake, a relatively large flood control reservoir in Mississippi with a history of contaminant bioaccumulation in fish. The post-construction sediments (after 1954) are discriminated from the pre-construction sediments (before 1954) based on depth variations in sediment texture and 137Cs emissions. The concentrations of select trace elements of the post-1954 sediments all are statistically greater than the pre-1954 sediments, and these same sediments also are enriched in clay. Once these concentrations are normalized by clay content, all trace elements in the post-1954 sediments are lower in concentration than the pre-1954 normalized sediments. Moreover, the trace elements when normalized by clay or Al content show virtually no change vertically (over time) within the reservoir impoundment. This suggests that the sources of these sediment-associated trace elements within Grenada Lake, whether natural or anthropogenic, have not changed appreciably over the lifespan of the reservoir and that the degradation of sedimentologic and ecologic indices within the lake are due to the sequestration of clay or clay-sized materials.

  1. Carbon Mineralization Pathways and Early Diagenesis in Lake Erie Sediments

    NASA Astrophysics Data System (ADS)

    O Neill, A. H.; Crowe, S. A.; Song, Z.; Mucci, A.; Sundby, B.; Fryer, B. J.; Fowle, D. A.

    2004-12-01

    In spite of the long-standing paradigm whereby organic matter degradation proceeds by redox reactions that consume oxidants in the order of free energy yield, diagenesis in marine and fresh water sediments often yield different results. The reasons for this are the highly variable absolute and relative abundances of electron acceptors and the different microbial populations found in freshwater environments. As contaminant availability and subsequent impact on aquatic ecosystems are directly linked to these transformations, it is important to understand the most important degradation pathways and their rates. To this end we have conducted chemical analyses of Lake Erie sediment pore-waters and a preliminary characterization of the vertical distribution of microbiological populations. Sediments were collected at four locations in the Central and Eastern basins of Lake Erie during cruises of the R/V LIMNOS in May and June of 2004 respectively. High-resolution vertical profiles of several redox-active species (O2, Fe2+, Mn2+, Fe3+ and S2-) have been obtained by voltammetry using Au/Hg amalgam micro-electrodes. These are the first high-resolution pore-water profiles obtained for multiple redox species using Au/Hg amalgam microelectrodes in the Great Lakes. These profiles show oxygen depletion to levels below detection (5 uM) at depths that range from <1 to 6 mm below the sediment-water interface. Frequently, there is up to 1 cm separation between the depth at which O2 became undetectable and the depth of the first measurable Mn2+. The vertical concentration profiles of Mn2+ and Fe2+ are highly variable between stations and seem to be related to the local bathymetry. Alternatively this variability may be related to the abundance of solid phase Mn and Fe at these sites. The presence of voltammetric peaks measured between -0.5 and -0.6 V, that are often attributed to dissolved organic Fe (III) species, could be produced as part of a strategy by Fe reducing microorganisms

  2. Organic sedimentation in modern lacustrine systems: A case study from Lake Malawi, East Africa

    USGS Publications Warehouse

    Ellis, Geoffrey S.; Barry J. Katz,; Christopher A. Scholz,; Peter K. Swart,

    2015-01-01

    This study examines the relationship between depositional environment and sedimentary organic geochemistry in Lake Malawi, East Africa, and evaluates the relative significance of the various processes that control sedimentary organic matter (OM) in lacustrine systems. Total organic carbon (TOC) concentrations in recent sediments from Lake Malawi range from 0.01 to 8.80 wt% and average 2.83 wt% for surface sediments and 2.35 wt% for shallow core sediments. Hydrogen index (HI) values as determined by Rock-Eval pyrolysis range from 0 to 756 mg HC g−1 TOC and average 205 mg HC g−1 TOC for surface sediments and 228 mg HC g−1 TOC for shallow core samples. On average, variations in primary productivity throughout the lake may account for ~33% of the TOC content in Lake Malawi sediments (as much as 1 wt% TOC), and have little or no impact on sedimentary HI values. Similarly, ~33% to 66% of the variation in TOC content in Lake Malawi sediments appears to be controlled by anoxic preservation of OM (~1–2 wt% TOC), although some component of the water depth–TOC relationship may be due to physical sediment transport processes. Furthermore, anoxic preservation has a minimal effect on HI values in Lake Malawi sediments. Dilution of OM by inorganic sediment may account for ~16% of variability in TOC content in Lake Malawi sediments (~0.5 wt% TOC). The effect of inputs of terrestrial sediment on the organic character of surface sediments in these lakes is highly variable, and appears to be more closely related to the local depositional environment than the regional flux of terrestrial OM. Total nitrogen and TOC content in surface sediments collected throughout the lake are found to be highly correlated (r2 = 0.95), indicating a well-homogenized source of OM to the lake bottom. The recurring suspension and deposition of terrestrial sediment may account for significant amounts of OM deposited in offshore regions of the lake. This process effectively separates denser

  3. Climatic record of the Iberian peninsula from lake Moncortes' sediments

    NASA Astrophysics Data System (ADS)

    Cao, Min; Huguet, Carme; Rull, Valenti; Valero, Blas; Rosell-Mele, Antoni

    2014-05-01

    Climatic record of the Iberian peninsula from lake Moncortes' sediments Min Cao1, Carme Huguet1, Valenti Rull2, Blas L. Valero-Garces3, Antoni Rosell-Melé1,4 1Institut de Ciència i Tecnologia Ambientals (ICTA), Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Catalonia, Spain; 2Institut de Botanic de Barcelona (CSIC), Passeig del Migdia s/n, 08038, Barcelona, Spain, 3 Instituto Pirenaico de Ecologıa (CSIC), Avda. Montañana 1005, 50059 Zaragoza, Spain, 4Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Catalonia, Spain. The continuing buildup of industrial greenhouse gases in the atmosphere and concomitant increase in global temperatures has made much of the world's society aware that decades to centuries of environmental change lie ahead, and that these will have profound economic, political and societal impacts. The Iberian Peninsula lies in the boundary between tropical and subtropical climates and seems to amplify the climatic signals form the northern hemisphere through both atmospheric and water circulation feedbacks, making it an ideal site to monitor Northern hemisphere climate changes. This extreme sensitivity to climatic changes also makes the Iberian Peninsula extremely vulnerable to future climate changes. This is why understanding sensitivity to climate change and the consequences it will have on both climate and the hydrological cycle is key to implement preventive measures. The aim of our study is to come up with a high resolution quantitative reconstruction of climate variability (temperature, production and precipitation) in the Iberian Peninsula from lake sediments. We also want to establish the relation between those changes and the ones observed in both ice cores from Greenland and paleotemperature records from marine sediments of the continental Iberian margin. For these reasons we sampled a core in Moncortes (42.3N, 0.99E), a lake of karstic origin with an average depth of 25m and an area of 0

  4. Chemical data for bottom sediment, lake water, bottom-sediment pore water, and fish in Mountain Creek Lake, Dallas, Texas, 1994-96

    USGS Publications Warehouse

    Jones, S.A.; Van Metre, P.C.; Moring, J.B.; Braun, C.L.; Wilson, J.T.; Mahler, B.J.

    1997-01-01

    Mountain Creek Lake is a reservoir adjacent to two U.S. Department of the Navy facilities, the Naval Weapons Industrial Reserve Plant and the Naval Air Station in Dallas, Texas. A Resource Conservation and Recovery Act Facility Investigation found ground-water plumes containing chlorinated solvents on both facilities. These findings led to a U.S. Geological Survey study of Mountain Creek Lake adjacent to both facilities between June 1994 and August 1996. Bottom sediments, lake water, bottom-sediment pore water, and fish were collected for chemical analysis.

  5. Sources of mercury in sediments, water, and fish of the lakes of Whatcom County, Washington

    USGS Publications Warehouse

    Paulson, Anthony J.

    2004-01-01

    Concerns about mercury (Hg) contamination in Lake Whatcom, Washington, were raised in the late 1990s after a watershed protection survey reported elevated concentrations of Hg in smallmouth bass. The U.S. Geological Survey, the Whatcom County Health Department, and the Washington State Department of Ecology (Ecology) cooperated to develop a study to review existing data and collect new data that would lead to a better understanding of Hg deposition to Lake Whatcom and other lakes in Whatcom County, Washington. A simple atmospheric deposition model was developed that allowed comparisons of the deposition of Hg to the surfaces of each lake. Estimates of Hg deposition derived from the model indicated that the most significant deposition of Hg would have occurred to the lakes north of the City of Bellingham. These lakes were in the primary wind pattern of two municipal waste incinerators. Of all the lakes examined, basin 1 of Lake Whatcom would have been most affected by the Hg emissions from the chlor-alkali plant and the municipal sewage-sludge incinerator in the City of Bellingham. The length-adjusted concentrations of Hg in largemouth and smallmouth bass were not related to estimated deposition rates of Hg to the lakes from local atmospheric sources. Total Hg concentrations in the surface sediments of Lake Whatcom are affected by the sedimentation of fine-grained particles, whereas organic carbon regulates the concentration of methyl-Hg in the surface sediments of the lake. Hg concentrations in dated sediment core samples indicate that increases in Hg sedimentation were largest during the first half of the 20th century. Increases in Hg sedimentation were smaller after the chlor-alkali plant and the incinerators began operating between 1964 and 1984. Analysis of sediments recently deposited in basin 1 of Lake Whatcom, Lake Terrell, and Lake Samish indicates a decrease in Hg sedimentation. Concentrations of Hg in Seattle precipitation and in tributary waters were

  6. Vertical profiles of sediment methanogenic potential and communities in two plateau freshwater lakes

    NASA Astrophysics Data System (ADS)

    Yang, Yuyin; Li, Ningning; Wang, Wei; Li, Bingxin; Xie, Shuguang; Liu, Yong

    2017-01-01

    Microbial methanogenesis in sediment plays a crucial role in CH4 emission from freshwater lake ecosystems. However, knowledge of the layer-depth-related changes of methanogen community structure and activities in freshwater lake sediment is still limited. The present study was conducted to characterize the methanogenesis potential in different sediment-layer depths and the vertical distribution of microbial communities in two freshwater lakes of different trophic status on the Yunnan Plateau (China). Incubation experiments and inhibitor studies were carried out to determine the methanogenesis potential and pathways. 16S rRNA and mcrA genes were used to investigate the abundance and structure of methanogen and archaeal communities, respectively. Hydrogenotrophic methanogenesis was mainly responsible for methane production in sediments of both freshwater lakes. The layer-depth-related changes of methanogenesis potential and the abundance and community structure of methanogens were observed in both Dianchi Lake and Erhai Lake. Archaeal 16S rRNA and mcrA genes displayed a similar abundance change pattern in both lakes, and the relative abundance of methanogens decreased with increasing sediment-layer depth. Archaeal communities differed considerably in Dianchi Lake and Erhai Lake, but methanogen communities showed a slight difference between these two lakes. However, methanogen communities illustrated a remarkable layer-depth-related change. Order Methanomicrobiales was the dominant methanogen group in all sediments, while Methanobacteriales showed a high proportion only in upper layer sediments. The trophic status of the lake might have a notable influence on the depth-related change pattern of methanogenesis activity, while the methanogen community structure was mainly influenced by sediment depth.

  7. The mineral magnetic record of magnetofossils in recent lake sediments of Lake Ely, PA

    NASA Astrophysics Data System (ADS)

    Kodama, K. P.; Moeller, R. E.; Bazylinski, D. A.; Kopp, R. E.; Chen, A. P.

    2013-11-01

    Mineral magnetic and ferromagnetic resonance (FMR) measurements made on the sediments from Lake Ely, Pennsylvania reveal the presence of magnetotactic bacteria magnetofossils. Saturation isothermal remanent magnetization (SIRM) data from a 1.25 m long piston core taken from the deepest part of the lake show a large intensity decrease at depths between 30 and 75 cm in the sediment column most likely the result of reductive diagenesis. Modeling of isothermal remanent magnetization (IRM) and anhysteretic remanent magnetization (ARM) acquisition data indicates the presence of biogenic soft (BS) and biogenic hard (BH) magnetosome coercivity components, even at depths in the core greatly affected by reductive diagenesis. First-order reversal curve distribution diagrams for two samples support this interpretation. Modeling of the FMR data also indicates the presence of the BS and BH magnetosome coercivity components, but the relative importance of the two components is opposite to that seen for the IRM and ARM acquisition modeling. A correlation between SIRM variations and local rainfall recorded over the past 70 years suggests that magnetofossil concentrations recorded paleo-rainfall variations in the most recent lake sediments. Multi-taper method spectral analysis of SIRM variations in the piston core, tied to time by varve counting from 1600 common era (CE) to 1128 before CE, show centennial scale periodicities similar to those observed in spectral analysis of a 230 year long historical rainfall record for the northeastern US reconstructed to Philadelphia, PA. This result indicates that enough magnetofossils can survive reductive diagenesis to retain a record of paleorainfall variations, suggesting that they can be a powerful paleoclimate proxy.

  8. Sediment transport and deposition in Lakes Marion and Moultrie, South Carolina, 1942-85

    USGS Publications Warehouse

    Patterson, G.G.; Cooney, T.W.; Harvey, R.M.

    1996-01-01

    Lakes Marion and Moultrie, two large reservoirs in the South Carolina Coastal Plain, receive large inflows of sediment from the Santee River. The average rate of sediment deposition for both lakes during the period 1942-85 was about 0.06 inch per year, or about 800 acre-feet per year. The rate during 1983-85 was about 0.037 inch per year, or about 490 acre-feet per year, reflecting the decreasing trend in sediment inflow. This is a reversal of a trend toward increasing suspended- sediment concentrations in streams that were caused by farming practices in the southern Piedmont from about 1800 to about 1920. Only a small part of the eroded sediment has been carried out of the Piedmont, but the remaining sediment is becoming less available for transport. Sediment deposition is concentrated in several areas of upper Lake Marion where the velocity of the incoming water decreases significantly. Beds of aquatic macrophytes appear to encourage deposition which, in turn, creates favorable habitat for the plants. The rate of sediment accumulation in Lakes Marion and Moultrie averaged 650,000 tons per year during 1983-85, reflecting a trap efficiency of 79 percent of the total sediment inflow of 825,000 tons per year. Thickness of post-impoundment sediment varies from about 11 feet near the mouth of the Santee River in Lake Marion to 0 feet in Lake Moultrie near Bonneau. Sediments in Lake Marion tend to have finer texture and higher contents of organic matter, nutrients, and trace metals than those in Lake Moultrie.

  9. Using multiple combined analytical techniques to characterize water extractable organic nitrogen from Lake Erhai sediment.

    PubMed

    Li, Zhang; Shengrui, Wang; Haichao, Zhao; Yanping, Li; Shouliang, Huo; Weibin, Qian; Yanli, Yang; Jie, Cheng

    2016-01-15

    In this study, UV-vis absorbance, fluorescence, and FT-IR spectroscopy were combined to characterize the components and structure of the water extractable organic nitrogen (WEON) in Lake Erhai sediment. Lake Erhai sediment WEON comprised predominantly high molecular weight WEON, with the fraction with a molecular weight>1kDa accounting for 87.7% of the total. It was mainly composed of humic acid-like substances, with fewer simple aromatic proteins. Large amounts of aliphatic and amide compounds were detected by IR in the sediments. There were more polymerizable aromatic rings and carbonyl, carboxyl, hydroxyl, and ester compounds in the high molecular weight WEON than in the low molecular weight WEON. Additionally, fluorescence regional integration results implied that the ratio PIII+V,n/PI+II+IV,n can be indirectly taken as an indicator for WEON content in Erhai sediments. Furthermore, the composition and structural characteristics of the WEON were found to be closely related with their properties in the sediment. The large amount of aliphatic compounds in the sediment as well as the relatively high humification and aromatic degree in high molecular weight WEON, stabilizes the WEON in Lake Erhai sediment. Compared with other lake sediments of different trophic statues (such as Lake Dianchi, Lake Poyang, Lake Taihu and Lake Donghu), Erhai sediment exhibited a higher degree of humification, which benefited for reducing sediment WEON releasing risk. And it can be regarded as the reason why the nutrient content in Erhai sediment is very high, but its water quality is still good.

  10. Distribution, fractionation and risk assessment of mercury in surficial sediments of Nansi Lake, China.

    PubMed

    Zhang, Wei; Cao, Feifei; Yang, Liyuan; Dai, Jierui; Pang, Xugui

    2017-03-01

    Nansi Lake is composed of four sub-lakes from north to south: Nanyang Lake, Dushan Lake, Zhaoyang Lake and Weishan Lake. An environmental pollution investigation was carried out to determine the fractionation, and pollution assessments of mercury (Hg) in surficial sediments from Nansi Lake. Results showed that the mean concentration of Hg was 3.1 times higher than its background value (0.015 mg kg(-1)), and the high concentration of Hg which even reached up to five times than the background value in the part of Dushan Lake and Weishan Lake, which indicated that there are obvious spatial differences. The content of Hg was positively correlated with that of total organic carbon, and negatively correlated with that of pH and SiO2 in surface sediments. An improved Tessier sequential extraction procedure was used to study the fractions of Hg in sediments. The results indicated that Hg existed primarily in the fraction of residual, which accounts for 58.4% of total mercury (THg), and the percentage of extractable Hg was only 1.93% of total mercury. High concentrations of mercury of non-residual phase were found in part lake area from the Nanyang Lake and the Weishan Lake, which indicating a higher potential ecological risk relative to the other lake areas. Based on the values of enrichment factor and geo-accumulation index, most part of Dushan Lake and Nanyang Lake and Weishan Lake were in a moderate pollution. And based on the fractionation of mercury, risk assessment code of Hg exhibited low risks to the environment in Nansi Lake.

  11. Magnetostratigraphy and Reversal Pattern of Pleistocene Lake Sediments from Armenia

    NASA Astrophysics Data System (ADS)

    Kirscher, U.; Bachtadse, V.; Bruch, A. A.; Gabrielyan, I.

    2011-12-01

    The Pleistocene geology of Armenia is dominated by the widespread occurrence of sediments recording recurring rapid and drastic changes of the environmental conditions during at least the last 2 million years. These sediments, predominantly diatomites, contain a huge variety of various fossil remains allowing the reconstruction of flora, fauna as well as the climatic conditions especially during dispersal of early man into Eurasia ~1.8 Ma ago. A detailed magnetostratigraphic study has been carried out in the Vorotan river area near the town of Sisian, southern Armenia, in order to establish a temporal correlation of six outcrops of paleo-lake sediments and to provide a timeframe for paleoenvironmental studies. A total number of 443 oriented drill cores was sampled at 6 sections with a sampling spacing between 5 and 20 cm. Detailed palaeomagnetic experiments revealed the presence of a characteristic direction of the remanent magnetization pointing either up and to the north or south and down. The resulting paleopole plots at 257.5°/81.6°. The profiles were interpreted to represent a clustering around the Jaramillo normal polarity subchron within the Matuyama reversed polarity chron, which is indicated by resulting normal polarity magnetic directions. They led to a roughly estimated duration of this lake sedimentation of roughly 350 kyrs. The high quality of the data and the high resolution sampling allows the construction of detailed Apparent Polar Wander (APW) Paths which yield additional information on the behavior of the Earth magnetic field during these field reversals. The pattern of the APW path is characterized by a complex and rather chaotic succession of transitional pole positions which are confined to broad bands across the Americas and the Eastern Pacific. Relative paleointensities were calculated using susceptibility as a normalizer. The usual decrease of relative intensity during the reversal is not visible, instead an intense fluctuation is

  12. Mercury in lake sediments of the Precambrian Shield near Huntsville, Ontario, Canada

    USGS Publications Warehouse

    Rasmussen, P.E.; Villard, D.J.; Fortescue, J.A.C.; Gardner, H.D.; Schiff, S.L.; Shilts, W.W.

    1998-01-01

    Long sediment cores (> 1 m) were collected from eight Precambrian Shield lakes in southern Ontario, Canada and analyzed for mercury (Hg), loss-on-ignition (LOI), and a suite of 36 other elements. Results indicated at least 100-fold variation in sediment Hg concentrations between lakes in close proximity (from 450 ppb), comparable to the variation reported for lakes across the whole of Canada. Strong areal correlations between Hg concentrations and LOI (r2=0.77), between Hg and other trace element concentrations (Pb, Zn, Cd, Sb, As, Br), and similarities in the vertical concentration profiles of Hg and LOI, all point to the importance of organic matter in the release, transport and redistribution of metals in watershed systems. The spatial pattern of Hg concentrations in deep, precolonial sediments (>20 cm) was found to mirror the pattern of Hg concentrations in modern surface sediments, an observation that was confirmed in a follow-up survey (r2= 0.85; n = 25 lakes), indicating that natural processes govern the unequal distribution of Hg among these lakes. Between-lake differences in surface sediment Hg concentrations normalized to organic carbon (Hg/C) were also reflected by Hg concentrations in small-mouth bass normalized to 35 cm length (R2=0.63; n= 15 lakes). The latter relationship suggests that small-mouth bass and lake sediment indicators provide mutually supportive information regarding Hg loading to the lacustrine environment from geological sources in the watershed system.

  13. Climatic change record during the past 1 Ma of the Lake Biwa sediments, Japan

    NASA Astrophysics Data System (ADS)

    Takemura, K.; Hayashida, A.; Danhara, T.

    2010-12-01

    Lake Biwa is the largest and oldest lake in Japan. The drilled core in 1982-1983 (i.e., the 1400 m core) has revealed ~900 m lake and terrestrial sediments overlying the basement rock (Takemura, 1990). The age data obtained from fission-track dating and tephra correlation indicated the discontinuity of the sedimentary sequence in present Lake Biwa. Recently, the doubt on discontinuity of the sequence in present Lake Biwa was completely cleared by the reinvestigation of the fission-track ages and tephra identification of Danhara et al. (2010). Improvements on fission track timescale have successfully identified the paleomagnetic data from middle Matuyama reversed Epoch including the Jaramillo event, determining time coverage of the Lake Biwa sediment as ~1.5 Ma. A highly linear sediment accumulation rate curve is thus given to the 900 m-deep Lake Biwa sediment. This secures the stable sedimentary environment of the basin, and the significance of Lake Biwa sediment as a good recorder for paleoclimate changes. Lake Biwa is, therefore, an ideal terrestrial site to explore paleoclimate and tectonic history during the past 1 Ma of East Asia. We summarize the data from multidiscipline approaches of pollen, diatom, geochemistry and paleomagnetic analyses using the drilling core in 1982-1983.

  14. Sediment oxygen demand in a constructed lake in south-eastern Australia.

    PubMed

    Wallace, Todd A; Ganf, George G; Brookes, Justin D

    2016-10-01

    The occurrence of hypoxia and anoxia in aquatic environments is increasing, driven by changes in land use and alteration of flow regimes. Periods of low oxygen impact biodiversity and water quality for both recreational and consumptive users. We use the Torrens Lake as a case study to assess pelagic, benthic and resuspended sediment oxygen demand, and the release of sediment bound phosphorus to determine the relative role of internal and external loading on water quality in a lake within a heavily urbanised landscape. Our results indicate temporal shifts in the dominant oxygen demanding process in the lake. During periods of no-inflow, sediment oxygen demand is the dominant process; during periods of inflow resulting from wet weather conditions, pelagic rather than sediment derived oxygen demand becomes the governing process. The inlet end of the lake is a depositional zone for stormwater borne sediments. Resuspended sediments at the inlet end of the lake exert a higher oxygen demand than those from the outlet, and represent a larger pool of potentially mobile phosphorus compared to sediments at the outlet end of the lake. However, external rather than internal loading appears to be the dominant driver of water quality in this lake.

  15. Dissolution of resin acids, retene and wood sterols from contaminated lake sediments.

    PubMed

    Meriläinen, Päivi; Lahdelma, Ilpo; Oikari, Laura; Hyötyläinen, Tarja; Oikari, Aimo

    2006-10-01

    The dissolution potency of hydrophobic resin acids (RAs), retene and wood sterols from sediments was studied. These wood extractives and their metabolites are sorbed from pulp and paper mill effluents to downstream sediments. With harmful components like these, sediments can pose a hazard to the aquatic environment. Therefore, sediment elutriates with water were produced under variable conditions (agitation rate and efficiency, time), and concentrations of the dissoluted compounds were analyzed. Both naturally contaminated field sediments and artificially spiked sediments were studied. By vigorous agitation RAs can be released fast from the sediment matrix and equilibrium reached within 3 days. Compared to RAs, desorption of retene from lake sediment was slower and did not completely reach equilibrium in 23 days. Sterols spiked to pristine sediment with a 33-day contact time desorbed faster than those associated authentically with industrial sediment of from a contaminated lake. Simulating the water turbulence adjacent to a sediment surface by low and high rate of agitation in the laboratory, an increase in the mixing rate after 43-day elutriation suddenly released a high amount of wood sterols. The results indicate wide variation between hazardous chemicals in their tendency to dissolution from sediment solids. Erosion and hydrology adjacent to the sediment surface, as well as risks from dredging activities of sediments, may expose lake biota to bioactive chemicals.

  16. Distribution of PCB congeners in seven lake systems: Interactions between sediment and food-web transport

    SciTech Connect

    MacDonald, C.R.; Metcalfe, C.D.; Balch, G.C.; Metcalfe, T.L. . Environmental and Resource Studies)

    1993-11-01

    A study was conducted to examine the role of two processes, partitioning of PCBs between sediment and biota and food-web transport, in determining the concentration of PCB congeners in the biota of seven lakes. Biota PCB concentration (lipid)-to-sediment PCB concentration (organic carbon), or BSF, ratios were calculated as markers of the partitioning of PCBs between biota and sediment, and biota PCB concentration (lipid)-to-zooplankton PCB concentration (lipid), or BAS, ratios were calculated as markers of the transport of PCBs through food webs. The lakes ranged from a shallow, well-mixed lake with a historic input of Aroclor technical mixtures to deeper, oligotrophic systems in which atmospheric deposition was the only known source. BSF ratios ranged from approximately one in cyprinids and zooplankton in all lakes to 30 in yellow perch in one lake. A significant correlation between lake maximum depth and combined BSF ratios for all biota indicated that PCBs were generally more available for accumulation in the shallower lakes, regardless of the PCB source. Principal component analysis (PCA) showed that the biota in the shallower lakes had higher ratios of higher chlorinated congeners, suggesting that predictions of equal concentrations of hydrophobic contaminants on a lipid basis in sediment and lower trophic levels may significantly underestimate the accumulation of very hydrophobic compounds in the organisms of some lake systems. BAF ratios ranged from approximately one in the lower trophic levels to approximately 10 in lake trout.

  17. Late quaternary sediments, minerals, and inferred geochemical history of Didwana Lake, Thar Desert, India

    USGS Publications Warehouse

    Wasson, R.J.; Smith, G.I.; Agrawal, D.P.

    1984-01-01

    Variations in clastic sediment texture, mineralogy of both evaporites formed at the surface and precipitates formed below the lake floor, and the relative chemical activities of the major dissolved components of the chemical precipitates, have allowed reconstruction of the history of salinity and water-level changes in Didwana Lake, Thar Desert, India. Hypersaline conditions prevailed at about the Last Glacial Maximum, with little evidence of clastic sediments entering the lake. Between ca. 13,000 and 6000 B.P. the lake level fluctuated widely, the lake alternately hypersaline and fresh, and clastic sediments were delivered to the lake at a low rate. Deep-water conditions occurred ca. 6000 B.P. and clastic influx increased abruptly. The water level dropped towards 4000 B.P. when the lake dried briefly. Since 4000 B.P. the lake has been ephemeral with a lowered rate of sedimentation and mildly saline conditions rather like those of today. This sequence of changes documented in the lake parallels changes in vegetation recorded in published pollen diagrams from both the Thar and the Arabian Sea. Correlation of the various lines of evidence suggests that the climate of the Last Glacial Maximum at Didwana was dry and windy with a weak monsson circulation. The monsson was re-established between ca. 13,000 and a little before 6000 B.P., and, when winter rainfall increased ca. 6000 B.P., the lake filled to its maximum depth. ?? 1984.

  18. Sediment magnetic and geochemical data from Quaternary lacustine sediment in two cores from Tule Lake, Siskiyou County, California

    USGS Publications Warehouse

    Best, Patti J.; Reynolds, Richard L.; Rosenbaum, Joseph G.; Dean, Walter E.; Honey, Jeannine; Drexler, John W.; Adam, David P.

    1996-01-01

    Sediment magnetic and geochemical results have been obtained from the top 60 meters of lacustrine sediments recovered in two cores from Tule Lake in northern California. The sediment magnetic and geochemical data, presented here in tabular form, complement studies of diatoms and pollen in the cores that are the bases for published paleoclimatic interpretations. This report also documents the methods used to obtain the magnetic properties and geochemical data.

  19. Sediment magnetic, paleomagnetic, and geochemical data from Quaternary lacustrine sediment in a core from Grass Lake, Siskiyou County, California

    USGS Publications Warehouse

    Best, Patti J.; Reynolds, Richard L.; Rosenbaum, Joseph G.; Drexler, John W.; Adam, David P.

    1996-01-01

    Sediment magnetic and geochemical results have been obtained from the top 60 meters of lacustrine sediments recovered in two cores from Tule Lake in northern California. The sediment magnetic and geochemical data, presented here in tabular form, complement studies of diatoms and pollen in the cores that are the bases for published paleoclimatic interpretations. This report also documents the methods used to obtain the magnetic properties and geochemical data.

  20. Arctic deltaic lake sediments as recorders of fluvial organic matter deposition

    NASA Astrophysics Data System (ADS)

    Vonk, Jorien; Dickens, Angela; Giosan, Liviu; Zipper, Samuel; Galy, Valier; Holmes, Robert; Montlucon, Daniel; Kim, Bokyung; Hussain, Zainab; Eglinton, Timothy

    2016-08-01

    Arctic deltas are dynamic and vulnerable regions that play a key role in land-ocean interactions and the global carbon cycle. Delta lakes may provide valuable historical records of the quality and quantity of fluvial fluxes, parameters that are challenging to investigate in these remote regions. Here we study lakes from across the Mackenzie Delta, Arctic Canada, that receive fluvial sediments from the Mackenzie River when spring flood water levels rise above natural levees. We compare downcore lake sediments with suspended sediments collected during the spring flood, using bulk (% organic carbon, % total nitrogen, 13C, 14C) and molecular organic geochemistry (lignin, leaf waxes). High-resolution age models (137Cs, 210Pb) of downcore lake sediment records (n=11) along with lamina counting on high-resolution radiographs show sediment deposition frequencies ranging between annually to every 15 years. Down-core geochemical variability in a representative delta lake sediment core is consistent with historical variability in spring flood hydrology (variability in peak discharge, ice jamming, peak water levels). Comparison with earlier published Mackenzie River depth profiles shows that (i) lake sediments reflect the riverine surface suspended load, and (ii) hydrodynamic sorting patterns related to spring flood characteristics are reflected in the lake sediments. Bulk and molecular geochemistry of suspended particulate matter from the spring flood peak and lake sediments are relatively similar showing a mixture of modern higher-plant derived material, older terrestrial permafrost material, and old rock-derived material. This suggests that deltaic lake sedimentary records hold great promise as recorders of past (century-scale) riverine fluxes and may prove instrumental in shedding light on past behaviour of arctic rivers, as well as how they respond to a changing climate.

  1. Developing inorganic carbon-based radiocarbon chronologies for Holocene lake sediments in arid NW China

    NASA Astrophysics Data System (ADS)

    Zhang, Jiawu; Ma, Xueyang; Qiang, Mingrui; Huang, Xiaozhong; Li, Shuang; Guo, Xiaoyan; Henderson, Andrew C. G.; Holmes, Jonathan A.; Chen, Fahu

    2016-07-01

    Inorganic carbonates are often used to establish radiocarbon (14C) chronologies for lake sediments when terrestrial plant remains (TPR) are rare or when bulk organic matter is insufficient for dating, a problem that is common for many lakes in arid regions. However, the reservoir effect (RE), as well as old carbon contributed from the lakes catchment make it difficult to establish reliable chronologies. Here we present a systematic study of inorganic 14C ages of two lake-sediment sequences, one from a small-enclosed saline lake - Lake Gahai in Qaidam Basin, and the other from a large freshwater lake - Lake Bosten in Xinjiang. Modern dissolved inorganic carbon (DIC) of the lakes, paleo-lake sediments exposed in the catchment, and mollusk shells in core sediments from Lake Gahai were dated to assess the RE and the contribution of pre-aged carbon to the old ages in the cores. We propose a statistical regression to assess more than one RE for the 14C carbonate ages within our sedimentary sequences. Old radiocarbon ages contributed by detrital carbonates were assessed by comparing the ages of mollusk shells with those of carbonates at the same sediment depths. We established the RE of the authigenic component and assessed detrital old carbon contributions to our two sites, and this was used to correct the 14C ages. Based on this approach, we developed age models for both cores, and tested them using 210Pb ages in both cores and TPR-based 14C-ages recovered from Lake Bosten. We further tested our age models by comparing carbonate-based oxygen isotope (δ18O) records from both lakes to an independently-dated regional speleothem δ18O record. Our results suggest if sedimentary sequences are densely dated and the RE and the contribution of old carbon from detrital carbonates can be ascertained, robust chronological frameworks based on carbonate-based 14C determinations can be established.

  2. Improved understanding of Diatom stratigraphy in a varved sediment through a sediment trap, lake monitoring and a catchment study

    NASA Astrophysics Data System (ADS)

    Maier, D. B.

    2015-12-01

    Biological sediment remains reflect past lake surrounding conditions. Potential drivers of change in the biological sediment proxy can be environmental contributors like weather and temperature changes as well as man-made such as developments in agriculture and forestry. However we don't know how these different factors contribute to the biological sediment signal. Here we are monitoring a boreal lake with a varved sediment to understand how the biological signal of diatom remains is formed in the annually layered sediment. We compare the diatom stratigraphy with a sequential sediment trap. For a deeper understanding of the underlying mechanisms we look at three full years of bi-weekly monitoring of physical, chemical and biological parameters and 15 years of water stratification data. We seek to link the monitored in-lake processes with the yearly environmental characteristics. The diatom sediment stratigraphy of the two most abundant species Asterionella formosa and Fragilaria delicatissima indicates three periods with a contrasting trend for both species from 1975 until 2014. In the first period Asterionella formosa is almost not abundant spanning one decade (1975-1985), reaching elevated abundance with a decreasing trend in period 2 over the following 17 years to be followed by a tripling of Asterionella fromosa remains in the sediment during the third period. The opposite trend is found for Fragilaria delicatissima. Linking the recorded data with the corresponding sediment stratigraphy allows us to distinguish between weather changes and catchment disturbances as potential drivers for changes in a sedimentary diatom signal.

  3. Sedimentation in Lake Onalaska, Navigation Pool 7, upper Mississippi River, since impoundment

    USGS Publications Warehouse

    Korschgen, C.E.; Jackson, G.A.; Muessig, L.F.; Southworth, D.C.

    1987-01-01

    Sediment accumulation was evaluated in Lake Onalaska, a 2800-ha backwater impoundment on the Upper Mississippi River. Computer programs were used to process fathometric charts and generate an extensive data set on water depth for the lake. Comparison of 1983 survey data with pre-impoundment (before 1937) data showed that Lake Onalaska had lost less than 10 percent of its original mean depth in the 46 years since impoundment. Previous estimates of sedimentation rates based on Cesium-137 sediment core analysis appear to have been too high. (DBO)

  4. Sedimentation in Lake Onalaska, Navigation Pool 7, Upper Mississippi River, since impoundment

    USGS Publications Warehouse

    Korschgen, C.E.; Jackson, G.A.; Muessig, L.F.; Southworth, D.

    1987-01-01

    Sediment accumulation was evaluated in Lake Onalaska a 2800-ha backwater impoundment on the Upper Mississippi River. Computer programs were used to process fathometric charts and generate an extensive data set on water depth for the lake. Comparison of 1983 survey data with pre-impoundment (before 1937) data showed that Lake Onalaska had lost less than 10 percent of its original mean depth in the 46 years since impoundment. Previous estimates of sedimentation rates based on Cesium-137 sediment core analysis appear to have been too high.

  5. Microscale characterization of sulfur speciation in lake sediments.

    PubMed

    Zeng, Teng; Arnold, William A; Toner, Brandy M

    2013-02-05

    Prairie pothole lakes (PPLs) are naturally sulfur-enriched wetlands in the glaciated prairie region of North America. High sulfate levels and dynamic hydrogeochemistry in combination render PPLs a unique environment to explore the speciation of sedimentary sulfur (S). The goals of this research were to define and quantify the solid-phase S pools in PPL sediments and track seasonal dynamics of S speciation. A quantitative X-ray microprobe method was developed based on S 1s X-ray absorption near-edge structure (XANES) spectroscopy and multienergy X-ray fluorescence mapping. Three S pools-pyritic S, reduced organic S (organic mono- and disulfide), and oxidized S (inorganic sulfate, ester sulfate, and sulfonate)-were identified in PPL sediments. No significant seasonal variation was evident for total S, but S speciation showed a seasonal response. During the spring-summer transition, the reduced organic S decreased from 55 to 15 mol %, with a concomitant rise in the oxidized S. During the summer-fall transition, the trend reversed and the reduced organic S grew to 75 mol % at the expense of the oxidized S. The pyritic S, on the other hand, remained relatively constant (∼22 mol %) over time. The seasonal changes in S speciation have strong potential to force the cycling of elements such as mercury in prairie wetlands.

  6. Distribution of atrazine and its phytoremediation by submerged macrophytes in lake sediments.

    PubMed

    Qu, Mengjie; Li, Huidong; Li, Na; Liu, Guanglong; Zhao, Jianwei; Hua, Yumei; Zhu, Duanwei

    2017-02-01

    We investigated sediments with high atrazine accumulation capability from 6 eutrophic lakes in Hubei Province of central China. Almost all lakes have atrazine in their sediments because of human activities. Honghu Lake and Liangzihu Lake were found to have higher levels of atrazine in sediment: 0.171 and 0.114 mg kg(-1), respectively. The results showed that lake sediments could adsorb atrazine six times faster than soils. The equilibrium partition coefficient of atrazine desorption (KPd) is much larger than the adsorption equilibrium partition coefficient (KPa) of atrazine, indicating that the residue of atrazine in water is easily immobilized by the sediments. Meanwhile, the incubation experiment showed that the removal rateof atrazine in Potamogeton crispus-planted and Myriophyllum spicatum-planted sediments reached >90%, while the rate in unplanted sediments was 77.2 ± 2.12% over 45 d. In unplanted sediment, the half-life of atrazine dissipation was 14.30 d, which was strongly enhanced by P. crispus and M. spicatum, greatly reducing the half-life to 8.60 and 9.72 d, respectively. These two submerged macrophytes are considered to be potential tools in the remediation of atrazine-contaminated sediments.

  7. Distribution and factors affecting adsorption of sterols in the surface sediments of Bosten Lake and Manas Lake, Xinjiang.

    PubMed

    Liu, Jiang; Yao, Xiaorui; Lu, Jianjiang; Qiao, Xiuwen; Liu, Zilong; Li, Shanman

    2016-03-01

    This study investigated the concentrations and distribution of eight sterol compounds in the surface sediments of Bosten Lake and Manas Lake, Xinjiang, China. The ratios of sterols as diagnostic indices were used to identify pollution sources. The sediment of the two lakes was selected as an adsorbent to investigate the adsorption behaviour of sterols. Results showed that the sterols were widely distributed in the sediments of the lakes in the study areas. The total concentrations of the detected sterols in Bosten Lake and in Manas Lake were 1.584-27.897 and 2.048-18.373 μg g(-1)∙dw, respectively. In all of the sampling sites, the amount of faecal sterols was less than that of plant sterols. β-sitosterol was the dominant plant sterol with a mean concentration of 2.378 ± 2.234 μg g(-1)∙dw; cholesterol was the most abundant faecal sterol with a mean concentration of 1.060 ± 1.402 μg g(-1)∙dw. The pollution level was higher in Bosten Lake than in Manas Lake. Majority of the ratios clearly demonstrated that the contamination by human faecal sources was occurring at stations which are adjacent to residential areas and water inlets. The adsorption behaviour of sterols to sediment suggested that the sterol adsorption coefficients were reduced as temperature increased. As salinity increased, the adsorption quantity also increased. As pH increased, the sediment adsorption of sterol slightly increased because the strong alkaline solution is not conducive to the adsorption of sterols. The ratios between sterols did not change largely with the change in external factors.

  8. Hydrological reconstruction from tree rings and varved lake sediments

    NASA Astrophysics Data System (ADS)

    Fortin, D.; Nicault, A.; Francus, P.; Bégin, Y.; Perreault, L.; Arsenault, D.; Bégin, C.; Savard, M. M.; Marion, J.; Guiot, J.

    2011-12-01

    The ARCHIVES project aims at reconstructing the annual hydro-climatic variability of the boreal region of the Quebec-Labrador Peninsula (Canada) over the past millennia. The project is based on tree-ring chronologies of more than one hundred years-old black spruce stands, several millennial tree-ring chronologies developed from sub-fossil trees and a network of lake sediment cores over a territory of more than 700 000 km2 (1400km in longitude x 500km in latitude). The dendrochronological network includes various tree-ring proxies such as ring width, ring density and ∂13C and ∂18O series. An extensive search for annually laminated lakes in the area permitted the identification of several sites with a strong potential for hydro-climatic reconstitution using annual varve thickness, grain size variability and sub-annual lamination as proxies for changes in river competency. We present here a 300 years-long reconstruction of hydrological variables at the watershed scale (annual water supply, spring and summer runoff) and some climate variables used in hydrologic forecast models, including an atmospheric index used by the modelling team of Hydro-Quebec (hydroelectric power supplier) to forecast spring flood volumes using both tree rings and annually laminated sediments. The sensitivity of the tree-ring chronologies and of varved series to hydrologic parameters were tested using statistical response functions. Our reconstruction methodology combines an analogue technique for the estimation of missing tree-ring data with an artificial neural network for optimal nonlinear calibration, including a bootstrap error assessment. Transfer functions were calibrated with water supply and meteorological data provided by Hydro-Quebec, and with Climate Research Unit (CRU) gridded climate data. The reconstructed series were validated using Reduction error (RE) and Root mean square error (RMSE) coefficients, standard cross-validation tests and verified with independent instrumental

  9. Radium-226 in water, sediments, and fish from lakes near the city of Elliot Lake, Ontario, Canada.

    PubMed

    Clulow, F V; Davé, N K; Lim, T P; Avadhanula, R

    1998-01-01

    Ra-226 was measured by alpha-emission spectroscopy in water, sediments, and fish (tissues and gut contents), from five lakes in a watershed containing U mining and milling operations at Elliot Lake, Ontario, and from control lakes in an adjacent non-industrialized watershed. Ra-226 transfer parameters from lake water and sediments to fish tissues, and annual intakes by humans consuming fish, were estimated. Mean dissolved 226Ra levels ranged from approximately 76 mBq litre(-1) in water of the most affected lake, to < 10 mBq litre(-1) in control lakes. Levels in summer were consistently higher than in fall or winter; no consistent variation with depth was noted. Sediment levels ranged from approximately 3000 mBq g(-1) dry wt in one study lake to < 100 mBq g(-1) dry wt of sediment in control lakes. Bone 226Ra concentrations were higher than in muscle. The lake trout (Salvelinus namaycush), a predatory secondary consumer, had bone 226Ra levels (< 20 mBq g(-1) dry wt) that did not show significant site variation. In contrast, bottom feeding whitefish had significantly more 226Ra in bone tissue (to 38 mBq g(-1) dry wt in the lake whitefish, Coregonus clupeaformis, and 76 mBq g(-1) in round whitefish, Prosopium cylindraceum) in study lakes than in controls (< 20 mBq g(-1) dry wt). Ra-226 levels in lake trout muscle were low and showed erratic variation among lakes whereas levels in whitefish muscle did not vary significantly among study and control sites. Lake herring (= cisco, Coregonus artedii), a planktivorous fish taken only from Quirke Lake, had mean 226Ra levels of 18 and 1.4 mBq g(-1) dry wt in bone and muscle, respectively. Gut 226Ra levels, highest in lake trout from McCabe and Quirke Lakes (126 +/- 53, 64 +/- 44 mBq g(-1) dry wt, respectively), and just detectable in McCabe and Elliot Lake whitefish (24 +/- 2, 36 +/- 14 mBq g(-1) dry wt, respectively), were below detection in lake trout and whitefish from other lakes. Concentration ratios (CRs) of 226Ra from

  10. Sediment nitrification and denitrification rates in a Lake ...

    EPA Pesticide Factsheets

    Microbially-mediated nitrogen (N) cycling in aquatic sediments has been recognized as an ecosystem service due to mitigation of N-transport to receiving waters. In 2011 and 2012, we compared nitrification (NIT), unamended (DeNIT) and amended (DEA) denitrification rates among spatial and depths zones and in relation to site physicochemical characteristics in the St. Louis River Estuary (SLRE) of western Lake Superior. Among vegetated habitats in 2011, NIT rates were highest in deep (>2 m) waters (249 mgN m-2 d-1) and in the upper estuary (>126). DeNIT rates were highest in deep waters and the harbor (2,111 and 274, respectively). DEA rates were similar among habitats. In 2012, we observed highest NIT (223 and 287) and DeNIT (77 and 64) rates in the harbor and from deep waters, respectively. Highest rates for NIT, DeNIT, and DEA were in July, May, and June, respectively. Individual site characteristics were weakly related to N-cycling rates, but water and sediment N-concentrations were identified as significant predictors in multiple linear regression models. NO3- was most limiting to sediment denitrification rates. The SLRE acted as a net source of NO3- to the water column, but had the potential to act as a sink. Average N2O production in 2011 was half that of 2012, with production during DEA (23-54%) being higher than DeNIT (0-41%). SLRE N-cycling rates were spatially and temporally variable, but our results give an indication of how alterations of water depth a

  11. Assessment of Bathymetry and Sediment Accumulation of Walker Lake, PA with Multiple Frequency GPR Antennas

    NASA Astrophysics Data System (ADS)

    Lachhab, A.; Booterbaugh, A.; Beren, M.

    2012-12-01

    Silting within all man-made reservoirs, can be a major problem. Exploring bathymetry with electromagnetic prospection tools is one way to identify the magnitude of sediment accumulation in lakes and reservoirs. In this study, the bathymetry and sediment accumulation of Walker Lake, PA was explored via multi-frequency ground penetrating radar (GPR) surveys. Walker Lake is located on the North Branch Middle Creek, which is a tributary to Middle Creek within the Susquehanna River basin. The technique developed in this study included two antennas positioned on a medium size inflatable boat towed by a 14' flat-bottom Jon Boat. Both 400 and 100 MHz antennas were deployed and sediment thickness and distribution throughout the lake were identified. A total of eighteen transects were taken along the entire length of the lake. A new method with multiple approaches including RADAN 7, GPR Viewer, SAS 9.1.3 and MATLAB was developed to generate three-Dimensional and contour surface of the pre-1971 Topography and bathymetry based on GPR reflection readings. As a result, depth, accumulation and rate of sedimentation in the lake were successfully measured. The lake was found to vary between 0.5 to 9 meters in depth. Sediment accumulation and distribution were calculated from the difference between the surveyed bathymetry and the 1971 pre-existent landscape topography. Sediment was found to accumulate thickest within the old channel of Middle Creek however, the bulk of the sediment volume lied outside this channel. Sediment deposition accumulates mainly upstream near the inlet to the lake and gradually decreases toward the dam inversely proportional to the depth of the lake.

  12. Unusual Holocene and late Pleistocene carbonate sedimentation in Bear Lake, Utah and Idaho, USA

    USGS Publications Warehouse

    Dean, W.; Rosenbaum, J.; Skipp, G.; Colman, S.; Forester, R.; Liu, A.; Simmons, K.; Bischoff, J.

    2006-01-01

    Bear Lake (Utah-Idaho, USA) has been producing large quantities of carbonate minerals of varying mineralogy for the past 17,000 years. The history of sedimentation in Bear Lake is documented through the study of isotopic ratios of oxygen, carbon, and strontium, percent organic carbon, percent CaCO3, X-ray diffraction mineralogy, HCl-leach inorganic geochemistry, and magnetic properties on samples from three piston cores. Historically, the Bear River, the main source of water for Great Salt Lake, did not enter Bear Lake until it was artificially diverted into the lake at the beginning of the 20th century. However, during the last glacial interval, the Bear River did enter Bear Lake depositing red, calcareous, silty clay. About 18,000 years ago, the Bear River became disconnected from Bear Lake. A combination of warmer water, increased evaporation, and increased organic productivity triggered the precipitation of calcium carbonate, first as calcite. As the salinity of the lake increased due to evaporation, aragonite began to precipitate about 11,000 years ago. Aragonite is the dominant mineral that accumulated in bottom sediments of the lake during the Holocene, comprising an average of about 70 wt.% of the sediments. Aragonite formation in a large, cold, oligotrophic, high latitude lake is highly unusual. Lacustrine aragonite usually is found in small, saline lakes in which the salinity varies considerably over time. However, Bear Lake contains endemic ostracodes and fish, which indicate that the chemistry of the lake has remained fairly constant for a long time. Stable isotope data from Holocene aragonite show that the salinity of Bear Lake increased throughout the Holocene, but never reached highly evolved values of ??18O in spite of an evaporation-dominated water balance. Bear Lake hydrology combined with evaporation created an unusual situation that produced large amounts of aragonite, but no evaporite minerals.

  13. Biogeochemical and microbial seasonal dynamics between water column and sediment processes in a productive mountain lake: Georgetown Lake, MT, USA

    NASA Astrophysics Data System (ADS)

    Parker, Stephen R.; West, Robert F.; Boyd, Eric S.; Feyhl-Buska, Jayme; Gammons, Christopher H.; Johnston, Tyler B.; Williams, George P.; Poulson, Simon R.

    2016-08-01

    This manuscript details investigations of a productive, mountain freshwater lake and examines the dynamic relationship between the chemical and stable isotopes and microbial composition of lake bed sediments with the geochemistry of the lake water column. A multidisciplinary approach was used in order to better understand the lake water-sediment interactions including quantification and sequencing of microbial 16S rRNA genes in a sediment core as well as stable isotope analysis of C, S, and N. One visit included the use of a pore water sampler to gain insight into the composition of dissolved solutes within the sediment matrix. Sediment cores showed a general decrease in total C with depth which included a decrease in the fraction of organic C combined with an increase in the fraction of inorganic C. One sediment core showed a maximum concentration of dissolved organic C, dissolved inorganic C, and dissolved methane in pore water at 4 cm depth which corresponded with a sharp increase in the abundance of 16S rRNA templates as a proxy for the microbial population size as well as the peak abundance of a sequence affiliated with a putative methanotroph. The isotopic separation between dissolved inorganic and dissolved organic carbon is consistent with largely aerobic microbial processes dominating the upper water column, while anaerobic microbial activity dominates the sediment bed. Using sediment core carbon concentrations, predictions were made regarding the breakdown and return of stored carbon per year from this temperate climate lake with as much as 1.3 Gg C yr-1 being released in the form of CO2 and CH4.

  14. Laboratory-determined phosphorus flux from lake sediments as a measure of internal phosphorus loading.

    PubMed

    Ogdahl, Mary E; Steinman, Alan D; Weinert, Maggie E

    2014-03-06

    Eutrophication is a water quality issue in lakes worldwide, and there is a critical need to identify and control nutrient sources. Internal phosphorus (P) loading from lake sediments can account for a substantial portion of the total P load in eutrophic, and some mesotrophic, lakes. Laboratory determination of P release rates from sediment cores is one approach for determining the role of internal P loading and guiding management decisions. Two principal alternatives to experimental determination of sediment P release exist for estimating internal load: in situ measurements of changes in hypolimnetic P over time and P mass balance. The experimental approach using laboratory-based sediment incubations to quantify internal P load is a direct method, making it a valuable tool for lake management and restoration. Laboratory incubations of sediment cores can help determine the relative importance of internal vs. external P loads, as well as be used to answer a variety of lake management and research questions. We illustrate the use of sediment core incubations to assess the effectiveness of an aluminum sulfate (alum) treatment for reducing sediment P release. Other research questions that can be investigated using this approach include the effects of sediment resuspension and bioturbation on P release. The approach also has limitations. Assumptions must be made with respect to: extrapolating results from sediment cores to the entire lake; deciding over what time periods to measure nutrient release; and addressing possible core tube artifacts. A comprehensive dissolved oxygen monitoring strategy to assess temporal and spatial redox status in the lake provides greater confidence in annual P loads estimated from sediment core incubations.

  15. Recent increases in sediment and nutrient accumulation in Bear Lake, Utah/Idaho, USA

    USGS Publications Warehouse

    Smoak, J.M.; Swarzenski, P.W.

    2004-01-01

    This study examines historical changes in sediment and nutrient accumulation rates in Bear Lake along the northeastern Utah/Idaho border, USA. Two sediment cores were dated by measuring excess 210Pb activities and applying the constant rate of supply (CRS) dating model. Historical rates of bulk sediment accumulation were calculated based on the ages within the sediment cores. Bulk sediment accumulation rates increased throughout the last 100 years. According to the CRS model, bulk sediment accumulation rates were <25mg cm-2 year-1 prior to 1935. Between 1935 and 1980, bulk sediment accumulation rates increased to approximately 40mg cm -2 year-1. This increase in sediment accumulation probably resulted from the re-connection of Bear River to Bear Lake. Bulk sediment accumulation rates accelerated again after 1980. Accumulation rates of total phosphorus (TP), total nitrogen (TN), total inorganic carbon (TIC), and total organic carbon (TOC) were calculated by multiplying bulk sediment accumulation rates times the concentrations of these nutrients in the sediment. Accumulation rates of TP, TN, TIC, and TOC increased as a consequence of increased bulk sediment accumulation rates after the re-connection of Bear River with Bear Lake.

  16. Perennially ice-covered Lake Hoare, Antarctica: physical environment, biology and sedimentation

    NASA Technical Reports Server (NTRS)

    Wharton, R. A. Jr; Simmons, G. M. Jr; McKay, C. P.; Wharton RA, J. r. (Principal Investigator)

    1989-01-01

    Lake Hoare (77 degrees 38' S, 162 degrees 53' E) is a perennially ice-covered lake at the eastern end of Taylor Valley in southern Victoria Land, Antarctica. The environment of this lake is controlled by the relatively thick ice cover (3-5 m) which eliminates wind generated currents, restricts gas exchange and sediment deposition, and reduces light penetration. The ice cover is in turn largely controlled by the extreme seasonality of Antarctica and local climate. Lake Hoare and other dry valley lakes may be sensitive indicators of short term (< 100 yr) climatic and/or anthropogenic changes in the dry valleys since the onset of intensive exploration over 30 years ago. The time constants for turnover of the water column and lake ice are 50 and 10 years, respectively. The turnover time for atmospheric gases in the lake is 30-60 years. Therefore, the lake environment responds to changes on a 10-100 year timescale. Because the ice cover has a controlling influence on the lake (e.g. light penetration, gas content of water, and sediment deposition), it is probable that small changes in ice ablation, sediment loading on the ice cover, or glacial meltwater (or groundwater) inflow will affect ice cover dynamics and will have a major impact on the lake environment and biota.

  17. Perennially ice-covered Lake Hoare, Antarctica: physical environment, biology and sedimentation.

    PubMed

    Wharton, R A; Simmons, G M; McKay, C P

    1989-01-01

    Lake Hoare (77 degrees 38' S, 162 degrees 53' E) is a perennially ice-covered lake at the eastern end of Taylor Valley in southern Victoria Land, Antarctica. The environment of this lake is controlled by the relatively thick ice cover (3-5 m) which eliminates wind generated currents, restricts gas exchange and sediment deposition, and reduces light penetration. The ice cover is in turn largely controlled by the extreme seasonality of Antarctica and local climate. Lake Hoare and other dry valley lakes may be sensitive indicators of short term (< 100 yr) climatic and/or anthropogenic changes in the dry valleys since the onset of intensive exploration over 30 years ago. The time constants for turnover of the water column and lake ice are 50 and 10 years, respectively. The turnover time for atmospheric gases in the lake is 30-60 years. Therefore, the lake environment responds to changes on a 10-100 year timescale. Because the ice cover has a controlling influence on the lake (e.g. light penetration, gas content of water, and sediment deposition), it is probable that small changes in ice ablation, sediment loading on the ice cover, or glacial meltwater (or groundwater) inflow will affect ice cover dynamics and will have a major impact on the lake environment and biota.

  18. ORGANIC CARBON AND SUSPENDED SEDIMENT DYNAMICS IN WESTERN LAKE SUPERIOR COASTAL WETLANDS

    EPA Science Inventory

    Little is known about the influence of loading of sediment and organic carbon on coastal wetlands fringing the Laurentian Great Lakes. In conjunction with our studies of nutrient retention in coastal wetland ecosystems...

  19. DIATOM INDICATORS OF TOTAL PHOSPHORUS, SEDIMENTS, AND WATERSHED FOREST COVER IN LAKE MICHIGAN COASTAL, RIVERINE WETLANDS

    EPA Science Inventory

    Diatom assemblages are being investigated as response and diagnostic indicators as part of our Great Lakes coastal wetlands research designed to support the development of nutrient, habitat, and sediment criteria and to develop community- and landscape-level diagnostic indicator ...

  20. Wind-driven nearshore sediment resuspension in a deep lake during winter

    NASA Astrophysics Data System (ADS)

    Reardon, Kristin E.; Bombardelli, Fabián. A.; Moreno-Casas, Patricio A.; Rueda, Francisco J.; Schladow, S. Geoffrey

    2014-11-01

    Ongoing public concern over declining water quality at Lake Tahoe, California-Nevada (USA) led to an investigation of wind-driven nearshore sediment resuspension that combined field measurements and modeling. Field data included: wind speed and direction, vertical profiles of water temperature and currents, nearbed velocity, lakebed sediment characteristics, and suspended sediment concentration and particle size distribution. Bottom shear stress was computed from ADV-measured nearbed velocity data, adapting a turbulent kinetic energy method to lakes, and partitioned according to its contributions attributed to wind-waves, mean currents, and random motions. When the total shear stress exceeded the critical shear stress, the contribution to overall shear stress was about 80% from wind-waves and 10% each from mean currents and random motions. Therefore, wind-waves were the dominant mechanism resulting in sediment resuspension as corroborated by simultaneous increases in shear stress and total measured sediment concentration. The wind-wave model STWAVE was successfully modified to simulate wind-wave-induced sediment resuspension for viscous-dominated flow typical in lakes. Previous lake applications of STWAVE have been limited to special instances of fully turbulent flow. To address the validity of expressions for sediment resuspension in lakes, sediment entrainment rates were found to be well represented by a modified 1991 García and Parker formula. Last, in situ measurements of suspended sediment concentration and particle size distribution revealed that the predominance of fine particles (by particle count) that most negatively impact clarity was unchanged by wind-related sediment resuspension. Therefore, we cannot assume that wind-driven sediment resuspension contributes to Lake Tahoe's declining nearshore clarity.

  1. Magnetic Properties of Surface Sediments in Small Temperate Lakes: Modern Analogues for Paleolimnologic Research

    NASA Astrophysics Data System (ADS)

    Lascu, I.; Plank, C.

    2007-12-01

    Magnetic properties of lake sediments are routinely measured as part of paleolimnological and paleoclimatic research. Basic parameters such as magnetic susceptibility (MS), anhysteretic remanent magnetization (ARM), and isothermal remanent magnetization (IRM) are used for correlating cores from different sites in the same basin, tracking erosion history and lake level changes, or investigating eutrophication and microbial processes. However, a detailed investigation of the syn-depositional processes that control the distribution of magnetic minerals across lake basins is lacking for most types of lake systems. In order to understand the main controls on environmental magnetic records, we systematically investigated the magnetic properties of surface sediments collected along transects in nine Minnesota lakes. The lakes are small (<1 sq. km), have simple morphologies, are hydrologically closed, and are distributed across an east-west moisture gradient, as well as a north-south temperature gradient. The structure of lake water columns was investigated by measuring temperature, specific conductivity, dissolved oxygen, and pH. Sediment composition was determined via loss on ignition (LOI). The magnetic properties of the sediments reflect the change in depositional environments from shallow to deep water, as defined in sedimentological context by LOI and sediment granulometry. All lake basins exhibit a characteristic pattern in terms of concentration (MS and IRM) and grain size (ARM/IRM) of magnetic minerals. Sediments above wave base (0.5 m) have high concentrations of coarse grained magnetic minerals. Below wave base, but in the thermally mixed layer, magnetic particles are finer-grained and present in lower concentrations. Profundal slope sediments are characterized by variable magnetic and compositional parameters, indicative of a dynamic sedimentological and geochemical environment. In the deep, anoxic regions, magnetic concentration increases again, associated

  2. Electricity generation by anaerobic bacteria and anoxic sediments from hypersaline soda lakes

    USGS Publications Warehouse

    Miller, L.G.; Oremland, R.S.

    2008-01-01

    Anaerobic bacteria and anoxic sediments from soda lakes produced electricity in microbial fuel cells (MFCs). No electricity was generated in the absence of bacterial metabolism. Arsenate respiring bacteria isolated from moderately hypersaline Mono Lake (Bacillus selenitireducens), and salt-saturated Searles Lake, CA (strain SLAS-1) oxidized lactate using arsenate as the electron acceptor. However, these cultures grew equally well without added arsenate using the MFC anode as their electron acceptor, and in the process oxidized lactate more efficiently. The decrease in electricity generation by consumption of added alternative electron acceptors (i.e. arsenate) which competed with the anode for available electrons proved to be a useful indicator of microbial activity and hence life in the fuel cells. Shaken sediment slurries from these two lakes also generated electricity, with or without added lactate. Hydrogen added to sediment slurries was consumed but did not stimulate electricity production. Finally, electricity was generated in statically incubated "intact" sediment cores from these lakes. More power was produced in sediment from Mono Lake than from Searles Lake, however microbial fuel cells could detect low levels of metabolism operating under moderate and extreme conditions of salt stress. ?? 2008 US Government.

  3. Electricity generation by anaerobic bacteria and anoxic sediments from hypersaline soda lakes.

    PubMed

    Miller, Laurence G; Oremland, Ronald S

    2008-11-01

    Anaerobic bacteria and anoxic sediments from soda lakes produced electricity in microbial fuel cells (MFCs). No electricity was generated in the absence of bacterial metabolism. Arsenate respiring bacteria isolated from moderately hypersaline Mono Lake (Bacillus selenitireducens), and salt-saturated Searles Lake, CA (strain SLAS-1) oxidized lactate using arsenate as the electron acceptor. However, these cultures grew equally well without added arsenate using the MFC anode as their electron acceptor, and in the process oxidized lactate more efficiently. The decrease in electricity generation by consumption of added alternative electron acceptors (i.e. arsenate) which competed with the anode for available electrons proved to be a useful indicator of microbial activity and hence life in the fuel cells. Shaken sediment slurries from these two lakes also generated electricity, with or without added lactate. Hydrogen added to sediment slurries was consumed but did not stimulate electricity production. Finally, electricity was generated in statically incubated "intact" sediment cores from these lakes. More power was produced in sediment from Mono Lake than from Searles Lake, however microbial fuel cells could detect low levels of metabolism operating under moderate and extreme conditions of salt stress.

  4. MERCURY IN METAL ORE DEPOSITS: AN UNRECOGNIZED, WIDESPREAD SOURCE TO LAKE SUPERIOR SEDIMENTS, CONTRIBUTION #1072

    EPA Science Inventory

    Mining operations have worked the rich mineral resources of the Lake Superior Basin for over 150 years, leaving industrially impacted regions with tailing piles and smelters. In Lake Superior sediments, mercury and copper inventories increase towards shorelines and are highly cor...

  5. 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...

  6. Bottom Sediment as a Source of Organic Contaminants in Lake Mead, Nevada, USA

    EPA Science Inventory

    Treated wastewater effluent from Las Vegas, Nevada and surrounding communities’ flow through Las Vegas Wash (LVW) into the Lake Mead National Recreational Area at Las Vegas Bay (LVB). Lake sediment is a likely sink for many hydrophobic synthetic organic compounds (SOCs); however,...

  7. NATURAL RECOVERY OF PCB - CONTAMINATED SEDIMENTS IN A FRESH WATER LAKE

    EPA Science Inventory

    Abstract: An ongoing study of natural recovery of sediments contaminated with polychlorinated biphenyls (PCBs), sponsored by the U.S. Environmental Protection Agency (EPA), is being pursued at the Sangamo-Weston/Twelvemile Creek/Lake Hartwell Superfund Site (i.e., the Lake Hart...

  8. Agricultural pesticides in Mississippi Delta oxbow lake sediments during autumn and their effects on Hyalella azteca

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agricultural pesticide contamination of sediments from five Mississippi Delta oxbow lakes and their effects and bioavailablity to Hyalella azteca were assessed during a low-application season, autumn. Three reference oxbow lakes were located in the White River National Wildlife Refuge (WRNWR), Arka...

  9. Sediment-Chlorophyll Relationship in Oxbow Lakes in the Mississippi River Alluvial Plain

    Technology Transfer Automated Retrieval System (TEKTRAN)

    During of the past century, aquatic habitats have declined worldwide, primarily due to draining and clearing for agriculture and urban development. These activities often result in increased erosion and sedimentation with detrimental impacts on stream and lake water quality. Oxbow lakes are importa...

  10. Sediment quality assessment of Beasley Lake: Bioaccumulation and effects of pesticides in Hyalella azteca

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Beasley Lake is a Conservation Evaluation Assessment Program (CEAP) watershed in the intensively cultivated Mississippi Delta, USA. Lake sediment quality at three sites was evaluated in 2004 and 2008 for biological impairment and uptake (viz. body residues) from 14 pesticides and three metabolites ...

  11. Viable endospores of Thermoactinomyces vulgaris in lake sediments as indicators of agricultural history.

    PubMed Central

    Nilsson, M; Renberg, I

    1990-01-01

    Bacteria of the genus Thermoactinomyces form endospores with an extreme longevity in natural habitats. We isolated Thermoactinomyces sacchari from 9,000-year-old varved (annually laminated) sediment; thus, T. sacchari is probably one of the oldest known living organisms. More importantly, we tested and verified the hypothesis that there is a relationship between concentrations of dormant, viable endospores of T. vulgaris in lake sediments and the extent of agriculture in the catchments of the lakes. In surface sediments, low concentrations were recorded in forest lakes and the concentrations increased with increasing areas of cultivated land around the lakes. In varved sediment cores from three lakes, we found a temporal relationship between records of T. vulgaris endospores and the pollen of plants indicating agriculture. Endospores were very rare in sediments deposited before agriculture, ca. 1100 A.D. From then to between 1300 and 1700 A.D., a period with restricted cultivation, low but more regular rates of accumulation of endospores were recorded. High endospore accumulation rates were found with the subsequent agricultural expansion. This investigation confirms suggestions that this bacterium could be used as a paleoindicator for agricultural activity and be complementary to pollen analyses. Viable bacteria in continuous records of lake sediments are also potential material for evolutionary studies. PMID:2202253

  12. [Suspension-sedimentation of sediment and release amount of internal load in Lake Taihu affected by wind].

    PubMed

    Pang, Yong; Yan, Run-run; Yu, Zhong-bo; Li, Yi-ping; Li, Rui-ling

    2008-09-01

    The water quality in Meiliang Bay of the Taihu Lake was totally tested five times in the four seasons. The suspension samples were obtained by using a sediment trap. The sediment settling flux and resuspended flux were calculated according to the observation data by using Gansith formula, and the relationships between these fluxes and wind speeds were established. Seven experiments were conducted in Laboratory for hydrostatic settling behavior of suspended matter affected by different wind speeds in Lake Taihu. The hydrostatic settling fluxes of suspended matter were calculated and the relationships between the fluxes and suspended matter concentrations were established. Base on these works, the suspension-sedimentation process was decomposed and generalized according to the critical wind speed of 3.7 m/s. Daily sediment resuspended amount and settling amount of the year 2005 was calculated and annual average release amount of internal load in Lake Taihu was estimated using the wind data of nearly 10 years. The results indicate that daily release amount of internal load in Lake Taihu significantly influenced by wind and have the same trend of change with wind, while the release amount of different nutrients in the same condition are different. The Lake Taihu has an annual average release amount of internal load with COD 49,600 t, TN 7773.0 t and TP 275.5 t, of which summer has the markedly highest release amount than other seasons.

  13. A hydrous Ca-bearing magnesium carbonate from playa lake sediments, Salines Lake, Spain

    USGS Publications Warehouse

    Queralt, I.; Julia, R.; Plana, F.; Bischoff, J.L.

    1997-01-01

    Sediments of playa Lake Salines, SE, Spain, contain a carbonate mineral characterized by X-ray diffraction peaks very similar to, but systematically shifted from those of pure magnesite. Analyses (SEM, IR and Raman spectroscopy, DTA, TGA, and ICP) indicate the mineral is a hydrous Ca-bearing magnesium carbonate with the chemical formula (Mg0.92,Ca0.08)CO3??3H2O. Thermal characteristics of the mineral are similar to those of other known hydrated magnesium carbonates. X-ray and electron diffraction data suggests a monoclinic system (P21/n space group) with unit-cell parameters of a = 6.063(6), b = 10.668(5), and c = 6.014(4) A?? and ?? = 107.28??.

  14. Unconsolidated sediments at the bottom of Lake Vostok from seismic data

    USGS Publications Warehouse

    Filina, I.; Lukin, V.; Masolov, V.; Blankenship, D.

    2007-01-01

    Seismic soundings of Lake Vostok have been performed by the Polar Marine Geological Research Expedition in collaboration with the Russian Antarctic Expedition since the early 1990s. The seismograms recorded show at least two relatively closely spaced reflections associated with the lake bottom. These were initially interpreted as boundaries of a layer of unconsolidated sediments at the bottom of the lake. A more recent interpretation suggests that the observed reflections are side echoes from the rough lake bottom, and that there are no unconsolidated sediments at the bottom of the lake. The major goal of this paper is to reveal the nature of those reflections by testing three hypotheses of their origin. The results show that some of the reflections, but not all of them, are consistent with the hypothesis of a non-flat lake bottom along the source-receiver line (2D case). The reflections were also evaluated as side echoes from an adjacent sloping interface, but these tests implied unreasonably steep slopes (at least 8 degrees) at the lake bottom. The hypothesis that is the most compatible with seismic data is the presence of a widespread layer of unconsolidated sediments at the bottom of Lake Vostok. The modeling suggests the presence of a two hundred meter thick sedimentary layer with a seismic velocity of 1700 -1900 m/sec in the southern and middle parts of the lake. The sedimentary layer thickens in the northern basin to ~350 m

  15. Low sediment-water gas exchange in a small boreal lake

    NASA Astrophysics Data System (ADS)

    Kokic, Jovana; Sahlée, Erik; Brand, Andreas; Sobek, Sebastian

    2016-09-01

    Boreal lake sediments are carbon sources by producing CO2. CO2 flux from sediments is partly controlled by turbulence in the water column, which is not given the same attention as CO2 production rates in current estimates of CO2 fluxes from sediments. We quantified the in situ CO2 flux across the sediment-water interface in a small (0.07 km2) lake in Sweden by measuring the in situ O2 flux with the Eddy Correlation (EC) method and using the apparent respiratory quotient (CO2 production:O2 consumption) derived from sediment incubations. We demonstrate that median CO2 flux estimated by EC was 70% smaller than estimated by sediment incubations with artificial water mixing (1.0 × 10-2 and 3.6 × 10-2 µmol C m-2 s-1, respectively). Additionally, we show that inducing artificial mixing of supernatant water in the incubation experiment has a positive effect on observed fluxes, enhancing CO2 flux by 30% compared to not mixing supernatant water. We suggest that the difference between the methods is due to the strong artificial water mixing in sediment incubations compared to the turbulent mixing in this small lake. Additionally, low O2 supply to sediment aerobic heterotrophic microbes during extended periods of low water currents can inhibit respiration and thus CO2 production. These findings suggest that the sediment contribution to total lake CO2 emission might currently be overestimated for small boreal lakes. Care should be taken when upscaling sediment CO2 flux derived from incubation experiments to entire basins of small lakes, as incubation experiments are unlikely to accurately mimic in situ bottom water currents and gas exchange.

  16. Disruptions of stream sediment size and stability by lakes in mountain watersheds: Potential effects on periphyton biomass

    USGS Publications Warehouse

    Myers, A.K.; Marcarelli, A.M.; Arp, C.D.; Baker, M.A.; Wurtsbaugh, W.A.

    2007-01-01

    The location of a stream reach relative to other landforms in a watershed is an important attribute. We hypothesized that lakes disrupt the frequency of finer, more mobile sediments and thereby change sediment transport processes such that benthic substrates are more stable (i.e., less mobile) below lakes than above lakes. In turn, we hypothesized that this reduced mobility would lead to greater periphyton biomass below lakes. We tested these hypotheses in study reaches above and below lakes in 3 mountain watersheds. To expand this comparison, we analyzed the relationship between sediment attributes and periphyton biomass in one watershed with and one watershed without a lake. We hypothesized that no clear pattern or change in sediment size or chlorophyll a (chl a) would be observed over a 3-km-long study reach without a lake. In contrast, we expected a clear discontinuity in both sediment size and chl a in a 7-km-long study reach interrupted by a lake. Average median sediment size (D50) was significantly larger (p < 0.01) in lake-outlet than lake-inlet reaches (41 mm vs 10 mm). Bed sediments in lake-outlet reaches were immobile during bankfull flows, whereas sediments at lake-inlet reaches were mobile during bankfull flows. Chlorophyll a was ???10x greater in lake-outlet reaches than in lake-inlet reaches, although this difference was not statistically significant (p = 0.17). The longitudinal analysis clearly showed geomorphic transitions in sediment size and mobility downstream of mountain lakes, and these geomorphic transitions might be associated with changes in periphyton biomass. Geomorphic transitions can alter sediment transport and should be considered in concert with other factors that are considered more commonly in benthic ecology, such as light, nutrients, and temperature. ?? 2007 by The North American Benthological Society.

  17. 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.

  18. [Analysis on the forms and release potential of nutrients in sediments from lakes in the West Jiangsu Province].

    PubMed

    Liu, Tao; Hu, Zhi-Xin; Yang, Liu-Yan; Xiao, Lin; Xi, Bei-Dou; Xu, Qi-Gong

    2012-09-01

    To probe the effect of nitrogen and phosphorus (P) in sediment on aqueous nutrient concentrations, forms of phosphorus, sediment water interface diffusion fluxes and phosphorus release and adsorption of 10 lakes in the west Jiangsu province were studied. Sediments were sequentially extracted by the modified Ruttenberg's method, and the result showed that inorganic phosphorus in sediments of the lakes was the major fraction of total phosphorus, but the proportion of bioavailable phosphorus was relatively low. Compared with the lakes in northern Jiangsu, the Fe-P was relatively high in sediments of lakes in southern Jiangsu. The diffusion fluxes of lakes were mainly based on NH4(+) -N diffusion in the west Jiangsu, and ions of most of lakes diffused from overlying water to sediment, NO3(-) -N diffused from sediment to overlying water in lakes except for Lake Hongze, Lake Shijiu and Lake Xuanwu. The condition leaning to acidic (pH < 4) or alkaline (pH > 10) was beneficial to phosphorus release, and except for Lake Xuanwu, the least amount of phosphorus released form sediment was higher in acidic condition than that in alkaline condition. The amount of phosphorus adsorption was increasing with temperature increase. Considering the phosphorus adsorption on native phosphorus polluted (NAP-polluted) sediments. All data of P adsorption on sediment samples collected from 7 lakes were fitted to the modified Langmuir model. And the values of the maximum adsorption capacity (Q(m)), phosphorus binding constant (k), native adsorbed exchangeable phosphorus (Q(NAP)), were subsequently obtained. The results showed that the adsorption amount of P in Lake Hongze and Lake Xuanwu was relatively low, which were liable to release P from sediments.

  19. Hydrocarbons in the surficial sediments of Lakes St. Clair, Erie, and Ontario

    NASA Astrophysics Data System (ADS)

    Nagy, E.; Mudroch, P.; Mudroch, A.; Thomas, R. L.

    1984-03-01

    Although the long-term effects and the fate of petroleum hydrocarbons in marine and freshwater environments are not fully understood, it is generally recognized that much of the oil released by accidental spills or by various land sources ends up in the sediment where it may remain for at least several years The present study was undertaken to collect some initial data on the hydrocarbon concentrations in surficial sediments of lakes St Clair, Erie, and Ontario The distribution of hydrocarbons in these lakes followed the general patterns found for a number of contaminants, in that the distribution tended to coincide with the outlines of the sedimentary basins The highest concentrations were found in the Western Basin of Lake Erie and in the inshore zone around the west end of the lake, suggesting major inputs from the Detroit River Apart from some spots of high concentration around known dumping grounds, the concentrations gradually diminish toward the east The distribution pattern in Lake Ontario may be more readily ascribed to water circulation patterns than to any specific source around the lake The hydrocarbon levels were found to be significantly lower than those in Lake Erie in Lake St Clair only trace quantities of hydrocarbons were found, suggesting either low inputs or low sedimentation/accumulation rates due to its shallowness Although the present survey was limited to the top 3 cm of the sediments, the resulting distribution patterns indicate the western end of Lake Erie as the area with the heaviest hydrocarbon loadings The results may also facilitate the selection of specific areas where core sampling coupled with more complete analysis of the extracts could yield significant information on the long-term accumulation of anthropogenic hydrocarbons, and on their persistence and transformations in Great Lakes sediments

  20. A Holocene Sediment Record From Lake Elsinore, Southern California: Evidence for Relative Lake Level Change and the Onset of ENSO.

    NASA Astrophysics Data System (ADS)

    Kirby, M. E.; Lund, S. P.; Poulsen, C. J.

    2003-12-01

    There are very few complete terrestrial, Holocene paleoclimate records from coastal southwestern North America. Lake Elsinore, located 120km southeast of Los Angeles, represents one of the only natural, non-playa lakes in the region. Furthermore, it is well documented that coastal southwestern North America is highly sensitive to changes in atmospheric circulation and its affect on regional hydrodynamics. As shown by Kirby et al. (in press), modern lake levels at Lake Elsinore respond directly to total annual precipitation, particularly winter season amounts. The lake is also located along the eastern Pacific Ocean where changes in ocean circulation and its thermal structure modulate the overlying atmosphere, and thus the adjacent continental climate. Here, we present two 7 meter sediment core records from Lake Elsinore spanning the entire Holocene. Although the cores are from the lake's littoral zone, they show surprisingly complete records with very little lithologic evidence for major hiatuses. A combination of sedimentological analyses (e.g., mass magnetic susceptibility (CHI); total percent carbonate; total organic matter) and lithologic descriptions provide insight to lake dynamics over the Holocene. Using the historical calibration between magnetic susceptibility and relative lake level (i.e., high lake levels = high CHI values and vice versa) from Kirby et al. (in press), we developed a first-order estimate of Holocene relative lake levels for Lake Elsinore. The historic calibration is extrapolated through the sediment record based on the assumption that, like today, first order lake level change is directly related to precipitation amount. Both total percent carbonate and total organic matter support our historical calibration between CHI and lake level. Our data suggest a relative increase in lake levels during the mid-Holocene (ca. 8,000 cal yr BP) and through to the present day. From this observation, we hypothesize that regional hydrology as linked to

  1. Impacts of Three Gorges Reservoir on the sedimentation regimes in the downstream-linked two largest Chinese freshwater lakes

    PubMed Central

    Zhou, Yongqiang; Jeppesen, Erik; Li, Jingbao; Zhang, Yunlin; Zhang, Xinping; Li, Xichun

    2016-01-01

    We studied the impacts of Three Gorges Reservoir (TGR) on the sedimentation regimes in the downstream-linked two largest Chinese freshwater lakes, Lake Dongting and Lake Poyang. Our results indicate that up to 1.73 × 109 t sediment was retained in TGR from June 2003 to December 2014. This resulted in a 145.9 × 106 t yr−1 decline in the suspended sediment load at Zhicheng and a 16.8 × 106 t yr−1 lower sediment flow from Yangtze River to Lake Dongting, which partially explains the 13.4 × 106 t yr−1 lower sedimentation in Lake Dongting during the post-TGR period. Furthermore, TGR resulted in a 0.5 ± 0.3 m reduction of the multi-year mean water level at the Lake Poyang outlet Hukou, accelerating the suspended sediment export discharge from the lake. The reduced sedimentation in Lake Poyang during the post-TGR period was estimated to 6.3 × 106 t yr−1. We estimate that a monthly mean concentration of sediment flow from TGR below 0.60 kg m−3 will lead to erosion in Lake Dongting and Lake Poyang. Better regulation of TGR may extend the life expectancy of the two vanishing large lakes. PMID:27748435

  2. Biomarkers and Metabolic Patterns in the Sediments of Evolving Glacial Lakes as a Proxy for Planetary Lake Exploration.

    PubMed

    Parro, Víctor; Blanco, Yolanda; Puente-Sánchez, Fernando; Rivas, Luis A; Moreno-Paz, Mercedes; Echeverría, Alex; Chong-Díaz, Guillermo; Demergasso, Cecilia; Cabrol, Nathalie A

    2016-11-28

    Oligotrophic glacial lakes in the Andes Mountains serve as models to study the effects of climate change on natural biological systems. The persistent high UV regime and evolution of the lake biota due to deglaciation make Andean lake ecosystems potential analogues in the search for life on other planetary bodies. Our objective was to identify microbial biomarkers and metabolic patterns that represent time points in the evolutionary history of Andean glacial lakes, as these may be used in long-term studies as microscale indicators of climate change processes. We investigated a variety of microbial markers in shallow sediments from Laguna Negra and Lo Encañado lakes (Región Metropolitana, Chile). An on-site immunoassay-based Life Detector Chip (LDChip) revealed the presence of sulfate-reducing bacteria, methanogenic archaea, and exopolymeric substances from Gammaproteobacteria. Bacterial and archaeal 16S rRNA gene sequences obtained from field samples confirmed the results from the immunoassays and also revealed the presence of Alpha-, Beta-, Gamma-, and Deltaproteobacteria, as well as cyanobacteria and methanogenic archaea. The complementary immunoassay and phylogenetic results indicate a rich microbial diversity with active sulfate reduction and methanogenic activities along the shoreline and in shallow sediments. Sulfate inputs from the surrounding volcanic terrains during deglaciation may explain the observed microbial biomarker and metabolic patterns, which differ with depth and between the two lakes. A switch from aerobic and heterotrophic metabolisms to anaerobic ones such as sulfate reduction and methanogenesis in the shallow shores likely reflects the natural evolution of the lake sediments due to deglaciation. Hydrodynamic deposition of sediments creates compartmentalization (e.g., sediments with different structure and composition surrounded by oligotrophic water) that favors metabolic transitions. Similar phenomena would be expected to occur on other

  3. Impacts of flamingos on saline lake margin and shallow lacustrine sediments in the Kenya Rift Valley

    NASA Astrophysics Data System (ADS)

    Scott, Jennifer J.; Renaut, Robin W.; Owen, R. Bernhart

    2012-11-01

    Studies of modern, Holocene, and Pleistocene sediments around saline to hypersaline, alkaline Lake Bogoria and Lake Magadi show that evidence of flamingo activity in marginal areas of these lakes is nearly ubiquitous. Flamingos produce discrete structures such as webbed footprints (~ 9 cm long, ~ 11 cm wide) and nest mounds (~ 30 cm wide, ~ 20 cm high), and they also extensively rework sediments in delta front, delta plain, and shoreline areas. Large (~ 0.5-2 cm in diameter), pinched, 'bubble pores' and ped-like mud clumps are formed by the trampling and churning of wet clay-rich sediments in these settings. Flamingo nest mounds, although superficially similar to some thrombolite mounds, are typically internally structureless, unless formed on pre-existing sediments that preserve internal structures. The flamingo mounds consist of a dense, packed oval-shaped core, a surrounding 'body' of packed sediment, and an external layer with a ped-like texture of clumped mud. The nests may contain open holes from roots or feather shafts incorporated into the nest, and (or) burrows produced once the nests are abandoned. In areas with high densities of flamingos, lake margin sediments may be preferentially compacted, particularly at breeding sites, and become resistant to subaerial erosion and the effects of transgressive ravinement on time scales ranging from seasons to tens of thousands of years. The relatively well-compacted nest mounds and associated sediments also contribute to the stability of delta distributary channels during regressive-transgressive cycles, and can lead to the minor channelization of unconfined flows where currents are diverted around nest mounds. Pleistocene exhumed surfaces of relatively well-indurated lake margin sediments at Lake Bogoria and Lake Magadi that are interpreted as combined regressive and transgressive surfaces (flooding surface/sequence boundary) preserve evidence of flamingo activities, and are overlain by younger, porous lacustrine

  4. Role of storms and forestry practices in sedimentation in an Oregon Coast Range Lake

    NASA Astrophysics Data System (ADS)

    Guerrero, F. J.; Richardson, K.; Hatten, J. A.; Wheatcroft, R. A.

    2015-12-01

    Contemporary harvesting practices have been shown to reduce sediment transport rates relative to historic practices; however, it is not well understood how these practices interact with climate to influence sediment flux and source. We are currently studying sedimentation rates in Loon Lake, in the Oregon Coast Range. The watershed of Loon Lake is 80% privately owned, and is therefore an ideal system for examining the effect of policy affected management shifts on water quality and sediment transport. We analyzed one 690cm core that represents about 1500yrs of sedimentation in the lake. We measured accumulation by layer thickness and character by proxies of elemental analysis, magnetic susceptibility, particle size, and bulk density. Radionuclides and radiocarbon dates provide an age model with depth downcore. Our preliminary results show that there is some evidence that the sedimentation rate in the lake decreased around the time of passing of the Oregon Forest Practices Act when climate is taken into account; pre-OFPA, the estimated mean sedimentation rate was 1.0 cm/year, and post-OFPA, the estimated mean sedimentation rate was 0.76 cm/year. Both of these sedimentation rates appear to be different than pre-European settlement period which averaged about 0.40 cm/year; however, this conclusion is preliminary. In general, it seems there is some evidence that the Best Management Practices instituted with OFPA are associated with lower sedimentation rates. In our presentation we will discuss the role of forestry and climate in changing these sedimentation rates and compare these modern sedimentation rates with sedimentation in the pre-settlement period.

  5. Sediment inflow, outflow and deposition for Lakes Marion and Moultrie, South Carolina, October 1983-March 1985

    USGS Publications Warehouse

    Cooney, T.W.

    1988-01-01

    In 1941 a Coastal Plain reach of the Santee River was impounded to form Lake Marion and diverted into a diked-off part of the Cooper River basin to form Lake Moultrie. Rates of sediment inflow and outflow of the lakes were determined by the U.S. Geological Survey for the periods July 1966 - June 1968 and October 1983 - March 1985. Total sediment discharge was estimated for two inflow stations and continuous streamflow monitors and automatic suspended-sediment samplers were used for computation of suspended-sediment discharge. Bedload discharge was computed by the modified Einstein procedure. Suspended-sediment discharge was monitored at three outflow stations, with the suspended-sediment concentration measured on a weekly basis. During the 1983-1985 study, mean annual suspended-sediment inflow to Lakes Marion and Moultrie was estimated to be 722,000 tons, and the outflow was estimated at 175,000 tons, for a trap efficiency of 76% and a deposition rate of about 547,000 tons/year. This is about 33% less than the deposition rate determined during the 1966-68 study. The deposition rate for suspended and bedload sediment during the 1983 - 1985 study was about 650,000 tons/year. (USGS)

  6. PREDICTION OF CONTAMINATED SEDIMENT TRANSPORT IN THE MAURICE RIVER-UNION LAKE, NEW JERSEY, USA

    EPA Science Inventory

    This paper describes a sediment and contaminant transport model and its application to the Maurice River-Union Lake system in southern New Jersey, USA for the purpose of characterizing and forecasting sediment and arsenic distributions before and after proposed dredging activitie...

  7. PREDICTION OF CONTAMINATED SEDIMENT TRANSPORT IN THE MAURICE RIVER-UNION LAKE, NEW JERSEY, USA

    EPA Science Inventory

    A sediment and contaminant transport model and its application to the Maurice River-Union Lake system in southern New Jersey, USA is described. The application is meant to characterize and forecast sediment and arsenic (As) distributions before and after proposed dredging activit...

  8. Enhanced Sorption of PAHs in Natural-Fire-Impacted Sediments from Oriole Lake, California

    EPA Science Inventory

    Surface sediment cores from Oriole Lake (CA) were analyzed for organic carbon (OC), black carbon (BC), and their δ13C isotope ratios. Sediments displayed high OC(20-25%) and increasing BC concentrations from ∼0.40% (in 1800 C.E.) to ∼0.60% dry weight (in 2000 C.E.). Petrographic...

  9. Quinone profiles in lake sediments: Implications for microbial diversity and community structures.

    PubMed

    Hiraishi, Akira; Kato, Kenji

    1999-10-01

    Microbial quinone compositions of sediment mud samples from five different lakes in Japan were studied by spectrochromatography and mass spectrometry. The total quinone content of these samples ranged from 1.97 to 18.0 nmol/g dry weight of sediment, of which a combined fraction of ubiquinones and menaquinones accounted for 42 to 74%. The remaining fraction (26 to 58%) consisted of the photosynthetic quinones, plastoquinones and phylloquinone. The sediment samples produced PQ-9 or Q-8 as the most abundant quinone type regardless of their geographic locations and depths. These results indicate that oxygenic phototrophic microorganisms and Q-8-containing proteobacteria constituted major parts of microbial populations in the lake sediment. In the surface water of the same sampling sites, plastoquinones and phylloquinone occurred in much higher proportions. These findings suggested that the high abundance of oxygenic phototrophs in the sediment muds resulted from their constant movement or sedimentation from the surface water. Numerical analyses of the quinone profiles showed that the microbial communities of the sediment were diverse and different in different lakes but similar to each other in the diversity of bioenergetic modes. Three physiological groups of microbes showing ubiquinone-mediated aerobic respiration, oxygenic photosynthesis, and menaquinone-associated respiration were suggested to inhabit the lake sediments in balance.

  10. MISSING THE STORM: PREDICTING SEDIMENT EXPORT FROM BASEFLOW CONDITIONS IN LOW-ORDER LAKE SUPERIOR WATERSHEDS

    EPA Science Inventory

    Midwestern streams export most of their annual sediment load during snowmelt and rainfall events, however measuring sediment export at peak stream discharges is not always possible. Watershed-level, riparian, and instream data were collected from 48 second and third order Lake S...

  11. Improving lakebed sediment quality in an urban estuary, Presque Isle Bay, Lake Erie, USA

    NASA Astrophysics Data System (ADS)

    Foyle, A. M.; Norton, K. P.

    2007-12-01

    Presque Isle Bay, Lake Erie, is a microtidal freshwater estuary on the North American Great Lakes. It is one of 40 remaining environmental Areas of Concern (AoCs) on the Great Lakes that have one or more water, habitat, or sediment quality impairments as defined by the International Joint Commission. In-situ natural capping using sediment from to-be-remediated watersheds and other sources is being considered as the most feasible means of remediating contaminated sediments in the estuary. A multi-decade sediment budget shows that, when localized anthropogenic effects are accounted for, the estuary net-accumulated sediment over time from three major sources: the Lake Erie littoral system (20%), streams (25%), and bank erosion and bluff recession (41%). The non-stream sources supply environmentally clean sediment from ancient coastal deposits along the shoreline, and from the modern littoral system. However, organic and metallic contaminants are supplied by streams and run-off and remain a remediation challenge. From a geological perspective, natural capping of contaminated sediment over the next several decades is a viable solution for the majority of the bay. The mechanism may not work effectively in all areas because approximately 25% of the bay floor is moderately net- erosional or accumulates sediments very slowly.

  12. Biological and chemical characterization of metal bioavailability in sediments from Lake Roosevelt, Columbia River, Washington, USA

    USGS Publications Warehouse

    Besser, J.M.; Brumbaugh, W.G.; Ivey, C.D.; Ingersoll, C.G.; Moran, P.W.

    2008-01-01

    We studied the bioavailability and toxicity of copper, zinc, arsenic, cadmium, and lead in sediments from Lake Roosevelt (LR), a reservoir on the Columbia River in Washington, USA that receives inputs of metals from an upstream smelter facility. We characterized chronic sediment toxicity, metal bioaccumulation, and metal concentrations in sediment and pore water from eight study sites: one site upstream in the Columbia River, six sites in the reservoir, and a reference site in an uncontaminated tributary. Total recoverable metal concentrations in LR sediments generally decreased from upstream to downstream in the study area, but sediments from two sites in the reservoir had metal concentrations much lower than adjacent reservoir sites and similar to the reference site, apparently due to erosion of uncontaminated bank soils. Concentrations of acid-volatile sulfide in LR sediments were too low to provide strong controls on metal bioavailability, and selective sediment extractions indicated that metals in most LR sediments were primarily associated with iron and manganese oxides. Oligochaetes (Lumbriculus variegatus) accumulated greatest concentrations of copper from the river sediment, and greatest concentrations of arsenic, cadmium, and lead from reservoir sediments. Chronic toxic effects on amphipods (Hyalella azteca; reduced survival) and midge larvae (Chironomus dilutus; reduced growth) in whole-sediment exposures were generally consistent with predictions of metal toxicity based on empirical and equilibrium partitioning-based sediment quality guidelines. Elevated metal concentrations in pore waters of some LR sediments suggested that metals released from iron and manganese oxides under anoxic conditions contributed to metal bioaccumulation and toxicity. Results of both chemical and biological assays indicate that metals in sediments from both riverine and reservoir habitats of Lake Roosevelt are available to benthic invertebrates. These findings will be used as

  13. 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

  14. Characterization of bottom-sediment, water, and elutriate chemistry at selected stations at Reelfoot Lake, Tennessee

    USGS Publications Warehouse

    Broshears, R.E.

    1991-01-01

    To better-understand and predict the potential effect of dredging on water quality at Reelfoot Lake, chemical analyses were conducted on samples of lake water, bottom sediment, and elutriate water. Chemical analyses were conducted on samples of lake water, bottom sediment, and elutriate water collected at five stations in the lake during November 1988. Lake water was of the calcium magnesium bicarbonate type with an average dissolved-solids concentration of 120 milligrams per liter. Trace constituents were present in bottom sediments at concentrations representative of their average relative abundance in the earth?s crust. Elutriate waters prepared by mixing bottom sediment and lake water had suspended-solids concentrations as high as 2,000 milligrams per liter which exerted significant oxygen demand Trace constituents in the unfiltered elutriate waters were elevated with respect to lake water; elevated concentrations were attributable to the increased suspended-solids concentrations. Concentrations of total-recoverable copper, lead., and zinc in many elutriate waters exceeded U.S. Environmental Protection Agency?s water-quality criteria for the protection of freshwater aquatic life. The toxicity of elutriate waters, as measured by a 48-hour bioassay with Ceriodaphnia dubia, was low.

  15. Paleomagnetic secular variation and environmental magnetism of Holocene-age sediments from Tulare Lake, CA

    NASA Astrophysics Data System (ADS)

    Roza, Janine; Jackson, Brandon; Heaton, Eric; Negrini, Rob

    2016-05-01

    The lake-level record from Tulare Lake, CA has been shown to provide valuable constraints on late Pleistocene and Holocene runoff from the Sierra Nevada mountain range into the San Joaquin Valley of California, one of the world's most prolific agricultural centers. This project uses the magnetic properties of the Tulare Lake sediments in order to date the sediments and to constrain the relative lake level at the time of deposition. Shallowing lake conditions were identified leading up to a prominent unconformity; magnetic mineralogy and grain size indicators, primarily decreasing ARM/IRM and S-Ratio values suggest coarser grain sizes and more oxidizing conditions. Approximately half of the samples possessed well-behaved paleomagnetic directions suitable for paleomagnetic secular variation dating. The results indicate that the sediments below the unconformity were deposited approximately 7600-8500 cal yr BP, and the sediments above the unconformity were deposited approximately 2500-800 cal yr BP. The ages of the corresponding sediments are consistent with the time intervals during which previous studies indicate that lake level was above the elevation of this site, before and after a mid Holocene regression.

  16. Paleomagnetic Secular Variation and Environmental Magnetism of Holocene-aged Sediments from Tulare Lake, CA

    NASA Astrophysics Data System (ADS)

    Roza, J.; Jackson, B.; Heaton, E.; Negrini, R. M.

    2015-12-01

    The lake-level record from Tulare Lake, CA has been shown to provide valuable constraints on late Pleistocene and Holocene channelized runoff from the Sierra Nevada mountain range into the San Joaquin Valley of California, one of the world's most prolific agricultural centers. This project focuses on the use of magnetic properties of the Tulare Lake sediments in order to test previous results by dating the sediments and determining the relative lake level at the time of deposition. Shallowing lake conditions were identified leading up to a prominent unconformity from magnetic mineralogy and grain size indicators, primarily decreasing ARM/IRM and S-Ratio values suggesting coarser grain sizes and more oxidizing conditions. Approximately half of the samples possessed well-behaved paleomagnetic directions suitable for paleomagnetic secular variation dating. The results indicate that the sediments below the unconformity were deposited approximately 7600-6700 14C years ago (~7600 to 8500 cal yr B.P.), and the sediments above the unconformity were deposited approximately 2200-500 14C years ago. The ages of the corresponding sediments are consistent with the time intervals during which lake level was predicted to be above the elevation of the Poso Canal site before and after a mid-Holocene regression.

  17. Early holocene trace metal enrichment in organic lake sediments, Baffin Island, Arctic Canada

    SciTech Connect

    Wolfe, A.P.; Haertling, J.W.

    1997-02-01

    Trace metals having accumulated in preindustrial ({sup 14}C dated) sediments from two small, acid-sensitive, arctic lakes show unexpected stratigraphic trends. Concentrations of Cu, Cr, Pb, Ni, and Zn have successive maxima in early to mid-Holocene sediments, of amplitudes comparable to lakes affected by loading from industrial atmospheric fallout. These profiles contrast sharply the concentrations of elements primarily associated with catchment erosion (Ti, V, Zr), and are attributed to the enhanced transport of organic-bound trace metals from the catchments to the lakes in the early Holocene. Paleoliminological conditions conferred effective sedimentary sinks for each of the enriched elements, although a certain degree of diagenetic mobilization is also observed. The study verifies that natural conditions may, under specific circumstances, produce sediment chemical signatures of potentially toxic metals that bear similarities to those reported from lakes adversely impacted by atmospheric pollution. 31 refs., 4 figs., 1 tab.

  18. A 500 year sediment lake record of anthropogenic and natural inputs to Windermere (English Lake District) using double-spike lead isotopes, radiochronology, and sediment microanalysis.

    PubMed

    Miller, Helen; Croudace, Ian W; Bull, Jonathan M; Cotterill, Carol J; Dix, Justin K; Taylor, Rex N

    2014-07-01

    A high-resolution record of pollution is preserved in recent sediments from Windermere, the largest lake in the English Lake District. Data derived from X-ray core scanning (validated against wavelength dispersive X-ray fluorescence), radiochronological techniques ((210)Pb and (137)Cs) and ultrahigh precision, double-spike mass spectrometry for lead isotopes are combined to decipher the anthropogenic inputs to the lake. The sediment record suggests that while most element concentrations have been stable, there has been a significant increase in lead, zinc, and copper concentrations since the 1930s. Lead isotope down-core variations identify three major contributory sources of anthropogenic (industrial) lead, comprising gasoline lead, coal combustion lead (most likely source is coal-fired steam ships), and lead derived from Carboniferous Pb-Zn mineralization (mining activities). Periods of metal workings do not correlate with peaks in heavy metals due to the trapping efficiency of up-system lakes in the catchment. Heavy metal increases could be due to flood-induced metal inwash after the cessation of mining and the weathering of bedrock in the catchment. The combination of sediment analysis techniques used provides new insights into the pollutant depositional history of Windermere and could be similarly applied to other lake systems to determine the timing and scale of anthropogenic inputs.

  19. Beach profile modification and sediment transport by ice: an overlooked process on Lake Michigan

    USGS Publications Warehouse

    Barnes, P.W.; Kempema, E.W.; Reimnitz, E.; McCormick, M.; Weber, W.S.; Hayden, E.C.

    1993-01-01

    Coastal lake ice includes a belt of mobile crash and slush ice and a stable nearshore-ice complex (NIC). Sediment concentrations indicate that the NIC and the belt of brash and slush contains 180 to 280 t (113 to 175m3) of sand per kilometer of coast. This static sediment load is roughly equivalent to the average amount of sand eroded from the bluffs and to the amount accumulating in the deep lake basin each year. Sediment is being rafted alongshore in the mobile brash and slush at rates of 10 to 30 cm/sec. -from Authors

  20. Characterization of the bacterial community in the sediment of a brackish lake with oyster aquaculture.

    PubMed

    Santander-De Leon, Sheila Mae S; Okunishi, Suguru; Kihira, Masaki; Nakano, Miyo; Nuñal, Sharon N; Hidaka, Masayasu; Yoshikawa, Takeshi; Maeda, Hiroto

    2013-01-01

    The physicochemical properties and bacterial community in sediments of Lake Shiraishi, a lake with brackish water, were characterized to elucidate the influence of oyster farming and seawater and freshwater inflow. Physicochemical analyses suggested the marine origin of the sediment at the mouth of the lake, while higher organic matter load and the resultant anaerobic, reductive condition of the sediments of the inner part were observed. The bacterial community in the sediments reflects these sediment environments: the bacterial community in the vicinities of oyster farms included sulfate-reducing bacteria (SRB) , although sulfur-oxidizing bacteria (SOB) were found at all the sampling sites. In addition, similarity of the band profiles obtained with 16S ribosomal RNA gene (16S rDNA) -denaturing gradient gel electrophoresis (DGGE) decreased in proportion to the distance from the mouth of the lake to the oyster farms in the inner part. This study was able to characterize the microbial community shift in brackish lake sediments with an oyster aquaculture system through the molecular fingerprinting technique, DGGE, in relation to their physicochemical characteristics.

  1. Spatial distribution and source apportionment of PFASs in surface sediments from five lake regions, China

    PubMed Central

    Qi, Yanjie; Huo, Shouliang; Xi, Beidou; Hu, Shibin; Zhang, Jingtian; He, Zhuoshi

    2016-01-01

    Perfluoroalkyl substances (PFASs) have been found in environment globally. However, studies on PFAS occurrence in sediments of lakes or reservoirs remain relatively scarce. In this study, two hundred and sixty-two surface sediment samples were collected from forty-eight lakes and two reservoirs all over China. Average PFAS concentrations in surface sediments from each lake or reservoir varied from 0.086 ng/g dw to 5.79 ng/g dw with an average of 1.15 ng/g dw. Among five lake regions, average PFAS concentrations for the lakes from Eastern Plain Region were the highest. Perfluorooctanoic acid, perfluoroundecanoic acid and perfluorooctane sulfonic acid (PFOS) were the predominant PFASs in surface sediments. The significant positive correlations between PFAS concentrations and total organic carbon, total nitrogen and total phosphorus contents in sediments revealed the influences of sedimentary characteristics on PFAS occurrence. A two-dimensional hierarchical cluster analysis heat map was depicted to analyze the possible origins of sediments and individual PFAS. The food-packaging, textile, electroplating, firefighting and semiconductor industry emission sources and the precious metals and coating industry emission sources were identified as the main sources by two receptor models, with contributions of 77.7 and 22.3% to the total concentrations of C4-C14- perfluoroalkyl carboxylic acids and PFOS, respectively. PMID:26947748

  2. Long Term Atmospheric and Erosional Pollution As Recorded in Lake Sediments from Yunnan, China

    NASA Astrophysics Data System (ADS)

    Hillman, A. L.; Abbott, M. B.; Yu, J.; Bain, D.; Chiou-Peng, T.

    2014-12-01

    Human activities including agriculture, metallurgy (e.g. mining, processing, smelting), and deforestation have altered cycles of erosion and sedimentation in lake environments for thousands of years. In the Yunnan province of southwestern China, where written records are incomplete, it is unclear when, where, and how much disturbance occurred. Lake sediments offer a means to investigate a wide variety of human activities. Here, we present a lake sediment record from Erhai (25°43'N, 100°12'E) based on trace metal concentrations that reveals substantial atmospheric and erosional pollution to the lake environment over the last 4,000 years. Sediments indicate the initiation of copper-based metallurgy at 3,600 years BP, the existence of which has been debated amongst archaeologists. Beginning 2,000 years BP, sedimentation rates increase and concentrations of metals such as aluminum, titanium, lead, and zinc increase. This is likely linked to increased sediment flux to the lake associated with the initiation of terraced agriculture according to historical documents. The most prominent feature of the record is an abrupt and intense increase in lead, silver, cadmium, and zinc beginning at 700 years BP. The peak of this increase occurs at 600 years BP and is consistent with historical records that the Mongols established the first government operated silver mine in Yunnan. Notably, the concentrations of lead during this time are an order of magnitude greater than modern day levels of pollution.

  3. An 84-kyr paleomagnetic record from the sediments of Lake Baikal, Siberia

    USGS Publications Warehouse

    Peck, J.A.; King, J.W.; Colman, Steven M.; Kravchinsky, V.A.

    1996-01-01

    We have conducted a paleomagnetic study of sediment cores obtained from the Selenga prodelta region of Lake Baikal, Russia. This record, which spans approximately the last 84 kyr, contributes to a better understanding of the nature of geomagnetic field behavior in Siberia and is a useful correlation and dating tool. We demonstrate that the Lake Baikal sediments are recording variations in the geomagnetic field. The directional record displays secular variation behavior with a geomagnetic excursion at 20 ka and additional excursions appearing as large-amplitude secular variation at 41, 61, and 67 ka. Smoothing of the geomagnetic excursion behavior occurs in Lake Baikal sediments owing to the intermediate sedimentation rate (13 cm kyr-1). The Lake Baikal relative paleointensity record correlates to absolute paleointensity data for the last 10 kyr and to relative paleointensity records from the Mediterranean Sea and Indian Ocean for the last 84 kyr. This correlation suggests a strong global (i.e., dipole) component to these records and further supports the reliability of sediments as recorders of relative geomagnetic paleointensity. We show that a relative geomagnetic intensity stratigraphy has a potential resolution of 7 kyr by correlating continental and marine records. The geomagnetic intensity stratigraphy helps constrain the age of the difficult to date Lake Baikal sediments.

  4. Spatial distribution and source apportionment of PFASs in surface sediments from five lake regions, China

    NASA Astrophysics Data System (ADS)

    Qi, Yanjie; Huo, Shouliang; Xi, Beidou; Hu, Shibin; Zhang, Jingtian; He, Zhuoshi

    2016-03-01

    Perfluoroalkyl substances (PFASs) have been found in environment globally. However, studies on PFAS occurrence in sediments of lakes or reservoirs remain relatively scarce. In this study, two hundred and sixty-two surface sediment samples were collected from forty-eight lakes and two reservoirs all over China. Average PFAS concentrations in surface sediments from each lake or reservoir varied from 0.086 ng/g dw to 5.79 ng/g dw with an average of 1.15 ng/g dw. Among five lake regions, average PFAS concentrations for the lakes from Eastern Plain Region were the highest. Perfluorooctanoic acid, perfluoroundecanoic acid and perfluorooctane sulfonic acid (PFOS) were the predominant PFASs in surface sediments. The significant positive correlations between PFAS concentrations and total organic carbon, total nitrogen and total phosphorus contents in sediments revealed the influences of sedimentary characteristics on PFAS occurrence. A two-dimensional hierarchical cluster analysis heat map was depicted to analyze the possible origins of sediments and individual PFAS. The food-packaging, textile, electroplating, firefighting and semiconductor industry emission sources and the precious metals and coating industry emission sources were identified as the main sources by two receptor models, with contributions of 77.7 and 22.3% to the total concentrations of C4-C14- perfluoroalkyl carboxylic acids and PFOS, respectively.

  5. Modeling Hydrodynamics, Water Temperature, and Suspended Sediment in Detroit Lake, Oregon

    USGS Publications Warehouse

    Sullivan, Annett B.; Rounds, Stewart A.; Sobieszczyk, Steven; Bragg, Heather M.

    2007-01-01

    Detroit Lake is a large reservoir on the North Santiam River in west-central Oregon. Water temperature and suspended sediment are issues of concern in the river downstream of the reservoir. A CE-QUAL-W2 model was constructed to simulate hydrodynamics, water temperature, total dissolved solids, and suspended sediment in Detroit Lake. The model was calibrated for calendar years 2002 and 2003, and for a period of storm runoff from December 1, 2005, to February 1, 2006. Input data included lake bathymetry, meteorology, reservoir outflows, and tributary inflows, water temperatures, total dissolved solids, and suspended sediment concentrations. Two suspended sediment size groups were modeled: one for suspended sand and silt with particle diameters larger than 2 micrometers, and another for suspended clay with particle diameters less than or equal to 2 micrometers. The model was calibrated using lake stage data, lake profile data, and data from a continuous water-quality monitor on the North Santiam River near Niagara, about 6 kilometers downstream of Detroit Dam. The calibrated model was used to estimate sediment deposition in the reservoir, examine the sources of suspended sediment exiting the reservoir, and examine the effect of the reservoir on downstream water temperatures.

  6. Historically and currently used Dechloranes in the sediments of the Great Lakes.

    PubMed

    Yang, Ruiqiang; Wei, Hua; Guo, Jiehong; McLeod, Colin; Li, An; Sturchio, Neil C

    2011-06-15

    Dechlorane (mirex), Dechlorane Plus (DP), Dechlorane 602 (Dec602), Dechlorane 603 (Dec603), Dechlorane 604 (Dec604), and Chlordecone (Kepone) were analyzed in 16 sediment cores collected in 2007 from the Great Lakes of North America. Results show that Lake Ontario sediments have accumulated mirex, DP, Dec602 and Dec604 in amounts 1 to 2 orders of magnitude higher than other Great Lakes. The chemical inventory decreases log-linearly with increasing latitude (N) and longitude (W) of the sampling locations, but Lake Ontario sites are outliers in the regression against latitude. The regression analyses suggest differences among the analytes with regard to source impact and long-range transport behavior. Temporal trends of input differ among lakes. Most sites in Lake Superior are still receiving increasing fluxes of DP and Dec602, while these have been declining in Lake Ontario from the peak around 1990. The relative abundance of the two DP isomers, represented by f(syn), increases with increasing distance from the potential discharge source in Niagara Falls, NY, suggesting the anti-DP isomer is more vulnerable to degradation during long-range atmospheric transport. Kepone was not detected in the sediments of Lakes Ontario, Erie, and Michigan.

  7. Quantified sensitivity of small lake sediments to record historic earthquakes: Implications for paleoseismology

    NASA Astrophysics Data System (ADS)

    Wilhelm, Bruno; Nomade, Jerome; Crouzet, Christian; Litty, Camille; Sabatier, Pierre; Belle, Simon; Rolland, Yann; Revel, Marie; Courboulex, Françoise; Arnaud, Fabien; Anselmetti, Flavio S.

    2016-01-01

    Seismic hazard assessment is a critical but challenging issue for modern societies. A key parameter to be estimated is the recurrence interval of damaging earthquakes. This requires the establishment of earthquake records long enough to be relevant, i.e., far longer than historical observations. We study how lake sediments can be used for this purpose and explore conditions that enable lake sediments to record earthquakes. This was achieved (i) through the compilation of eight lake-sediment sequences from the European Alps to reconstruct chronicles of mass movement deposits and (ii) through the comparison of these chronicles with the well-documented earthquake history. This allowed 24 occurrences of mass movements to be identified, of which 21 were most probably triggered by an earthquake. However, the number of earthquake-induced deposits varies between lakes of a same region, suggesting variable thresholds of the lake sequences to record earthquake shaking. These thresholds have been quantified by linking the mass movement occurrences in a single lake to both intensity and distance of the triggering earthquakes. This method offers a quantitative approach to estimate locations and intensities of past earthquake epicenters. Finally, we explored which lake characteristics could explain the various sensitivities. Our results suggest that sedimentation rate should be larger than 0.5 mm yr-1 so that a given lake records earthquakes in moderately active seismotectonic regions. We also postulate that an increasing sedimentation rate may imply an increasing sensitivity to earthquake shaking. Hence, further paleoseismological studies should control carefully that no significant change in sedimentation rates occurs within a record, which could falsify the assessment of earthquake recurrence intervals.

  8. Bacterial community composition of sediments from artificial Lake Maslak, Istanbul, Turkey.

    PubMed

    Balcı, Nurgul; Vardar, Nurcan; Yelboga, Emrah; Karaguler, Nevin Gul

    2012-09-01

    Small artificial lakes are ubiquitous in various natural environments. Small impoundments increase the residence time of water, thereby increasing the potential for retention of nutrients through biological and physical processes. We examined bacterial community structure of Lake Maslak, a small freshwater impoundment located in a densely populated region. The objective of our study was to investigate bacterial communities of the lake sediment which has not been determined and to elucidate the factors controlling bacterial diversity and the biogeochemical processes within the lake. For these purposes, surface water, lake bed sediments, and one core sample were collected. Microbiological characteristic of the lake bed and core sediments was determined by denaturing gradient gel electrophoresis targeting the 16S rRNA gene. Along with the microbiological studies, physicochemical (O(2), pH, temperature) and geochemical properties of the surface (NO (3) (-) , NO (2) (-) , NH (4) (+) ,PO (4) (-) ,SO (4) (2-) , K(+), Mg(2+), Ca(2+)) and pore water (K(+), Mg(2+), Ca(2+)) were determined in addition to heavy metals contents (Co Cu, Fe, Zn, Pb, Cd). Eight lake bed and one core sediments were also collected and analyzed for heavy metals and elemental compositions. Nitrate concentration in the surface water ranges from 0.27-1.8 mg/L, and ammonium (0.0-0.83 mg/L) appears to follow nitrate concentration. Sulfate concentration in the surface water (mean 60 mg/L) is greater than those measured in the pore water (mean, 37.5 mg/L). Fe, Zn, Pb, and Cd were not determined in the surface water, whereas Co was significantly higher both in the surface and pore water. Unlike Co, Pb, Zn, and Cd were not measured in the pore water. Lakebed and core sediments show significant enrichment in Pb, Zn, and Cu, indicating anthropogenic pollution. Consistent with geochemical parameters, microbiological analysis suggests a diverse bacterial community in the lake sediments and influence of

  9. Sedimentation in Whitewater Lake, Union County, east-central Indiana, 1959-88

    USGS Publications Warehouse

    Renn, D.E.

    1993-01-01

    Potential decreases in the storage capacity of Whitewater Lake based on whether dredging is continued or discontinued were estimated for the 29-year period 1989-2017. If dredging is continued, the potential for future decreases in the storage capacity of the lake is small. If dredging is discontinued, the volume of water in the lake in 2017 is estimated to be 88.2 percent of the 1959 volume; 11.8 percent of the 1959 volume of the lake would be filled with sediment.

  10. Sources and sinks of microplastics in Canadian Lake Ontario nearshore, tributary and beach sediments.

    PubMed

    Ballent, Anika; Corcoran, Patricia L; Madden, Odile; Helm, Paul A; Longstaffe, Fred J

    2016-09-15

    Microplastics contamination of Lake Ontario sediments is investigated with the aim of identifying distribution patterns and hotspots in nearshore, tributary and beach depositional environments. Microplastics are concentrated in nearshore sediments in the vicinity of urban and industrial regions. In Humber Bay and Toronto Harbour microplastic concentrations were consistently >500 particles per kg dry sediment. Maximum concentrations of ~28,000 particles per kg dry sediment were determined in Etobicoke Creek. The microplastic particles were primarily fibres and fragments <2mm in size. Both low- and high-density plastics were identified using Raman spectroscopy. We provide a baseline for future monitoring and discuss potential sources of microplastics in terms of how and where to implement preventative measures to reduce the contaminant influx. Although the impacts of microplastics contamination on ecosystem health and functioning is uncertain, understanding, monitoring and preventing further microplastics contamination in Lake Ontario and the other Great Lakes is crucial.

  11. Rock magnetic properties of sediments from Lake Sanabria and its catchment (NW Spain): paleoenvironmental implications

    NASA Astrophysics Data System (ADS)

    Larrasoaña, J. C.; Borruel, V.; Gómez-Paccard, M.; Rico, M.; Valero-Garces, B.; Moreno-Caballud, A.; Soto, R.

    2013-12-01

    Lake Sanabria is located in the NW Spanish mountains at 1000 m a.s.l., and constitutes the largest lake of glacial origin in the Iberian Peninsula. Here we present an environmental magnetic study of a Late Pleistocene-Holocene sediment core from Lake Sanabria and from different lithologies that crop out in its catchment, which includes Paleozoic plutonic, metamorphic and vulcanosedimentary rocks, and Quaternary deposits of glacial origin. This study was designed to complement sedimentologic and geochemical studies aimed at unraveling the climatic evolution of the NW Iberian Peninsula during the last deglaciation. Our results indicate that magnetite and pyrrhotite dominate the magnetic assemblage of both the sediments from the lower half of the studied sequence (25.6 - 13 cal kyr BP) deposited in a proglacial environment, and the Paleozoic rocks that make up most of the catchment of the lake. The occurrence of these minerals both in the catchment rocks and in the lake sediments indicates that sedimentation was then driven by the erosion of a glacial flour, which suffered minimal chemical transformation in response to a rapid and short routing to the lake. Sediments from the upper half of the studied sequence, accumulated after 12.4 cal kyr BP in a fluviolacustrine environment, contain magnetite and greigite. This points to a prominent role of post-depositional reductive dissolution, driven by a sharp increase in the accumulation of organic matter into the lake and the creation of anoxic conditions in the sediments, in shaping the magnetic assemblage of Holocene sediments. Pyrrhotite is stable under reducing conditions as opposed to magnetite, which is unstable. We therefore interpret that previous pedogenic processes occurred in the then deglaciated catchment of the lake were responsible for the oxidation of pyrrhotite and authigenic formation of magnetite, which survived subsequent reductive diagenesis given its initial larger concentrations. This interpretation is

  12. Surficial Geology of the Floor of Lake Mead (Arizona and Nevada) as Defined by Sidescan-Sonar Imagery, Lake-Floor Topography, and Post-Impoundment Sediment Thickness

    USGS Publications Warehouse

    Twichell, D.C.; Cross, V.A.

    2009-01-01

    Sidescan-sonar imagery collected in Lake Mead during 1999-2001, a period of high lake level, has been used to map the surficial geology of the floor of this large reservoir that formed upon completion of the Hoover Dam in 1935. Four surficial geologic units were identified and mapped: rock exposures and alluvial deposits that existed prior to the formation of the lake and thin post-impoundment sediments ( 1 m) deposited since the lake formed. Exposures of rock are most extensive in the narrow, steep-sided sections of the lake, while alluvial deposits are most extensive on the gentle flanks of the broader basin sections of the lake. Post-impoundment sediment is restricted to the floors of the original river valleys that now lie below lake level. These sediments are thickest in the deltas that form at the mouths of the Colorado River and its tributaries, but cover the entire length of the valley floors of the lake. This sediment distribution is consistent with deposition from turbidity currents. Lake level has dropped more than 30 m between collection of the sidescan imagery and publication of this report. During this time, thick delta deposits have been eroded and redistributed to deeper parts of the lake by turbidity currents. While present-day post-impoundment sediment distribution should be similar to what it was in 2001, the thickness may be greater in some of the deeper parts of the lake now.

  13. The glacial/deglacial history of sedimentation in Bear Lake, Utah and Idaho

    USGS Publications Warehouse

    Rosenbaum, J.G.; Heil, C.W.

    2009-01-01

    Bear Lake, in northeastern Utah and southern Idaho, lies in a large valley formed by an active half-graben. Bear River, the largest river in the Great Basin, enters Bear Lake Valley ???15 km north of the lake. Two 4-m-long cores provide a lake sediment record extending back ???26 cal k.y. The penetrated section can be divided into a lower unit composed of quartz-rich clastic sediments and an upper unit composed largely of endogenic carbonate. Data from modern fluvial sediments provide the basis for interpreting changes in provenance of detrital material in the lake cores. Sediments from small streams draining elevated topography on the east and west sides of the lake are characterized by abundant dolomite, high magnetic susceptibility (MS) related to eolian magnetite, and low values of hard isothermal remanent magnetization (HIRM, indicative of hematite content). In contrast, sediments from the headwaters of the Bear River in the Uinta Mountains lack carbonate and have high HIRM and low MS. Sediments from lower reaches of the Bear River contain calcite but little dolomite and have low values of MS and HIRM. These contrasts in catchment properties allow interpretation of the following sequence from variations in properties of the lake sediment: (1) ca. 26 cal ka-onset of glaciation; (2) ca. 26-20 cal ka-quasicyclical, millennial-scale variations in the concentrations of hematite-rich glacial fl our derived from the Uinta Mountains, and dolomite- and magnetite-rich material derived from the local Bear Lake catchment (reflecting variations in glacial extent); (3) ca. 20-19 cal ka-maximum content of glacial fl our; (4) ca. 19-17 cal ka-constant content of Bear River sediment but declining content of glacial fl our from the Uinta Mountains; (5) ca. 17-15.5 cal ka-decline in Bear River sediment and increase in content of sediment from the local catchment; and (6) ca. 15.5-14.5 cal ka-increase in content of endogenic calcite at the expense of detrital material. The onset

  14. Sediment dynamics and heavy metal pollution history of the Cruhlig Lake (Danube Delta, Romania).

    PubMed

    Begy, Róbert-Csaba; Preoteasa, Luminita; Timar-Gabor, Alida; Mihăiescu, Radu; Tănăselia, Claudiu; Kelemen, Szabolcs; Simon, Hedvig

    2016-03-01

    This is the first study reporting recent sedimentation rates data (e.g. the past 120-150 years) for the Cruhlig Lake situated in the Danube Delta. The aim of this study is to analyse the recent sedimentation rates using the (210)Pb dating method and identifying the heavy metal pollutants and their variability in time. Five sediment cores were taken with a gravity corer and - after drying the sliced samples-physical parameters, organic material and inorganic carbon content were determined. The total (210)Pb content was measured via (210)Po by alpha spectrometry, while supported (210)Pb was measured by (226)Ra (trough short life (222)Rn daughters) with HPGe detectors. Heavy metals were determined by ICP-MS; from the 64 measured elements, only exceeding values of Al, As, Cd, Co, Cs, Cr, Cu, Fe, Hg, K, Li, Mg, Mn, Ni, Pb and Zn are discussed. After applying the CRS model, ages and sedimentation rates were calculated. The average sedimentation rate of the Cruhlig Lake is 0.21 ± 0.02 g/cm(2)y, Minimum values (0.05 ± 0.003 g/cm(2)y) are registered along the eastern shoreline of the lake before 1913, while maximum values are recorded due to the flooding in 2006 in the western side (1.34 ± 0.12 g/cm(2)y). Recent sedimentation rates divide the lake into three areas: the secluded eastern near shore part (0.63 ± 0.07 g/cm(2)y), the centre of the lake (0.92 ± 0.05 g/cm(2)y) and the dynamic western area, where most sediment transport takes place (1.13 ± 0.01 g/cm(2)y). The sedimentation pattern proves this lake to be very sensitive to fluvial discharge fluctuations. The building of the Iron Gate dams (1972 and 1985) had a negative impact on the sedimentation decreasing it with 58.74%, while after 1989 these values grew 2.25 times. The lake received a quantity of sediment rich in heavy metals in 1992 ± 3 y, which settled mostly on the eastern part. Values for Cd, Co, Cr, Hg, Pb and Zn are up to five times higher in 1980 ± 5 y in the eastern part of the lake, while Cd, Co

  15. Microplastic pollution in Vembanad Lake, Kerala, India: The first report of microplastics in lake and estuarine sediments in India.

    PubMed

    Sruthy, S; Ramasamy, E V

    2017-03-01

    We present the first study of microplastics in the sediments of Vembanad Lake, a Ramsar site in India. Microplastics are emerging pollutants of increasing environmental concern with a particle size of <5 mm, which originate from successive degradation of larger plastic debris or are manufactured as small granules and used in many applications. The impact of microplastics pollution on the environment and biota is not well known. Vast data exist in the literature on marine microplastics while reports on freshwater ecosystems are scarce. In this context, to examine the occurrence of microplastic particles (MPs) in the Vembanad Lake, samples were collected from ten sites and processed for microplastic extraction through density separation. Identification of the polymer components of MPs was done using micro Raman spectroscopy. MPs were recovered from all sediment samples, indicating their extensive distribution in the lake. The abundance of MPs recorded from the sediment samples is in the range of 96-496 particles m(-2) with a mean abundance of 252.80 ± 25.76 particles m(-2). Low density polyethylene has been identified as the dominant type of polymer component of the MPs. As clams and fishes are the major source of protein to the local population, the presence of MPs in the lake becomes critically important, posing a severe threat of contaminating the food web of this lake. This study, being the first report from India on MPs in lake sediments, provide impetus for further research on the distribution and impact of this emerging pollutant on the biota of many aquatic systems spread across India.

  16. Characterization of heavy metals in water and sediments in Taihu Lake, China.

    PubMed

    Tao, Yu; Yuan, Zhang; Wei, Meng; Xiaona, Hu

    2012-07-01

    To explore a comprehensive status of heavy metals in the Taihu Lake, which is one of the most important waters in China, water and sediment samples were taken throughout the lake during April to May of 2010, and metal elements (Cu, Cd, Cr, Ni, Pb, Sn, Sb, Zn, Mn) were analyzed in the water column, interstitial water and sediment. Relevant standards were used to assess the sediment and water quality. Results show that, in the lake water column, the average concentration of all metals ranged from 0.047 μg/l (Cd) to 8.778 μg/l (Zn). The concentration in the river water was usually higher than in the lake water for many metals. In the interstitial water Mn was significantly higher than that in water column, and other metals had no significant difference between the two media. In the surface sediment, average metal content ranged from 1.325 mg/kg (Cd) to 798.2 mg/kg (Mn). Spatially, contents of many metals were higher in Zhushan Bay than in other lake areas, and there existed a clear content gradient from the river to the lake for both water and sediment. On the sediment profiles, many metals presented an increasing trend from the depth of 15-20 cm to the top, which is indicative of the impact of increasingly intensive human activities from that period. Quality assessment indicates that metals in water phase are generally safe compared with USEPA "National Recommended Water Quality Criteria," with the exception of Mn in the interstitial water and Sb in the river water. Whereas the sediment is widely contaminated with metals to some extent compared with the "Consensus-Based Sediment Quality Guidelines," and Cu, Cr, and Ni are more likely to raise ecological risks. This work could be a basis for the ongoing China's criteria strategy.

  17. PBDE, HBCD, and novel brominated flame retardant contamination in sediments from Lake Maggiore (Northern Italy).

    PubMed

    Poma, Giulia; Roscioli, Claudio; Guzzella, Licia

    2014-11-01

    The reduction in the use of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD) has opened the way for the introduction of novel brominated flame retardants (NBFRs) in place of the banned formulations. Important representatives of this group are decabromodiphenyl ethane (DBDPE), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), hexabromobenzene (HBB), and pentabromoethylbenzene (PBEB). In this study, the contamination due to NBRFs was investigated for the first time in Italy in the sediments of Lake Maggiore. The aim of the research was to characterize in detail the possible presence of temporal trends and/or to identify potential sources of contamination. The study also considered the PBDE and HBCD lake sediment's current contamination. The analytical results showed that sediments in Lake Maggiore and its tributary rivers had weak concentrations of PBEB, HBB, and BTBPE, but they did not have a negligible/insignificant contamination of HBCD (up to 23.7 ng/g dry weight (d.w.)). The determination of PBDEs in sediments showed that BDE-209 was the predominant congener (up to 217 and 28 ng/g d.w. in river and lake sediments, respectively). DBDPE was detected in the sediments with relevant concentrations (up to 280 ng/g d.w in the River Boesio sediments). The positive correlation of DBDPE with BDE-209 confirmed the wide and important use of this compound in the Lake Maggiore basin and the hypothesis that this compound will soon become one of the most important NBFRs used in Northern Italy. The contamination of Lake Maggiore sediments due to PBDEs, HBCD, and NBFRs were comparable to other worldwide situations.

  18. Environmental magnetic methods for detecting and mapping contaminated sediments in lakes

    NASA Astrophysics Data System (ADS)

    Boyce, J. I.

    2009-05-01

    The remediation of contaminated sediments is an urgent environmental priority in the Great Lakes and requires detailed mapping of impacted sediment layer thickness, areal distribution and pollutant levels. Magnetic property measurements of sediment cores from two heavily polluted basins in Lake Ontario (Hamilton Harbour, Frenchman's Bay) show that concentrations of hydrocarbons (PAH) and a number of heavy metals (Pb, As, Ni, Cu, Cr, Zn, Cd, Fe) are strongly correlated with magnetic susceptibility. The magnetic susceptibility contrast between the contaminated sediment and underlying 'pre-colonial' sediments is sufficient to generate a total field anomaly (ca. 2-20 nT) that can be measured with a magnetometer towed above the lake bed. Systematic magnetic surveying (550 line km) of Hamilton Harbour using a towed marine magnetometer clearly identifies a number of well-defined magnetic anomalies that coincide with known accumulations of contaminated lake sediment. When calibrated against in-situ magnetic property measurements, the modeled apparent susceptibility from magnetic survey results can be used to classify the relative contaminant impact levels. The results demonstrate the potential of magnetic property measurements for rapid reconnaissance mapping of large areas of bottom contamination prior to detailed coring and sediment remediation.

  19. Application of a comprehensive extraction technique for the determination of poly- and perfluoroalkyl substances (PFASs) in Great Lakes Region sediments.

    PubMed

    Guo, Rui; Megson, David; Myers, Anne L; Helm, Paul A; Marvin, Chris; Crozier, Patrick; Mabury, Scott; Bhavsar, Satyendra P; Tomy, Gregg; Simcik, Matt; McCarry, Brian; Reiner, Eric J

    2016-12-01

    A comprehensive method to extract perfluoroalkane sulfonic acids (PFSAs), perfluoroalkyl carboxylic acids (PFCAs), polyfluoroalkyl phosphoric acid diesters (diPAPs), perfluoroalkyl phosphinic acids (PFPiAs) and perfluoroalkyl phosphonic acids (PFPAs) from sediment and analysis by liquid chromatography tandem mass spectrometry (LC-MS/MS) was developed and applied to sediment cores from three small isolated lakes (Plastic Lake, Lake 442, Lake Tettegouche) and Lake Ontario in the Great Lakes Region. Recoveries of the target compounds using the optimized acetonitrile/sodium hydroxide extraction ranged from 73% to 120%. The greatest concentrations of per- and polyfluorinated alkyl substances (PFASs) were recorded in sediment from Lake Ontario (ΣPFASs 13.1 ng/g), where perfluorooctane sulfonic acid (PFOS) contributed over 80% of the total. Concentrations in Lake Ontario were approximately 1-2 orders of magnitude greater than the more remote lakes subject to primarily atmospheric inputs. Whilst the PFAS contribution in Lake Ontario was dominated by PFOS, the more remote lakes contained sediment with higher proportions of PFCAs. Trace amounts of emerging PFASs (diPAPs and PFPiAs) were found in very recent surface Lake Ontario and remote lake sediments.

  20. Diversity analysis of bacterial community compositions in sediments of urban lakes by terminal restriction fragment length polymorphism (T-RFLP).

    PubMed

    Zhao, Dayong; Huang, Rui; Zeng, Jin; Yan, Wenming; Wang, Jianqun; Ma, Ting; Wang, Meng; Wu, Qinglong L

    2012-11-01

    Bacteria are crucial components in lake sediments and play important role in various environmental processes. Urban lakes in the densely populated cities are often small, shallow, highly artificial and hypereutrophic compared to rural and natural lakes and have been overlooked for a long time. In the present study, bacterial community compositions in surface sediments of three urban lakes (Lake Mochou, Lake Qianhu and Lake Zixia) in Nanjing City, China, were investigated using the terminal restriction fragment length polymorphism (T-RFLP) of PCR-amplified 16S rRNA gene and clone libraries. Remarkable differences in the T-RFLP patterns were observed in different lakes or different sampling stations of the same lake. Canonical correspondence analysis indicated that total nitrogen (TN) had significant effects on bacterial community structure in the lake sediments. Chloroflexi were the most dominant bacterial group in the clone library from Lake Mochou (21.7 % of the total clones) which was partly associated with its higher TN and organic matters concentrations. However, Bacteroidetes appeared to be dominated colonizers in the sediments of Lake Zixia (20.4 % of the total clones). Our study gives a comprehensive insight into the structure of bacterial community of urban lake sediments, indicating that the environmental factors played a key role in influencing the bacterial community composition in the freshwater ecosystems.

  1. Late Holocene Hydrologic Variability Reconstruction of the Coastal Southwestern United States Using Lake Sediments from Crystal Lake, CA

    NASA Astrophysics Data System (ADS)

    Palermo, J. A.; Kirby, M. E.; Hiner, C.; Leeper, R. J.

    2014-12-01

    This study aims to reconstruct a high resolution, late Holocene record of precipitation variability for the coastal southwestern United States region using sediment cores from Crystal Lake, CA. This region is especially susceptible to droughts and episodic floods, making it of particular importance to understand past hydrologic variability. Crystal Lake is a small, alpine landslide dammed lake in the Angeles National Forest of the San Gabriel Mountains. The lake is the only permanent, freshwater lake located in the range. It is hydrologically closed, meaning all lake level changes are controlled by changes in precipitation: evaporation. To reconstruct past hydrologic variability, two Livingston piston cores were taken 15 m apart in the depocenter of the lake in May 2014. A multi-proxy methodology was utilized including: magnetic susceptibility, total organic matter and total carbonate content, grain size, and bulk d13Corg of sediments. All analyses were conducted at 1 cm contiguous intervals except bulk d13Corg (at 2 cm). Seismic reflection profiles were also generated to examine the basin's stratigraphic features in the context of the individual sediment cores. A working age model was provided by multiple AMS 14C dates from discrete organic matter (i.e., seeds, charcoal). Results from this study are compared to preexisting records of late Holocene hydrologic variability from coastal, central, and southern California. Further, the forcing mechanisms that drive hydrologic change (wet vs. dry episodes) in Southern California, such as ocean-atmosphere interactions including El Niño Southern Oscillation or the Pacific Decadal Oscillation, are discussed.

  2. Geo-feasibility of in situ sediment capping in a Great Lakes urban estuary: a sediment budget assessment

    NASA Astrophysics Data System (ADS)

    Foyle, Anthony M.; Norton, Kevin P.

    2007-10-01

    Presque Isle Bay is one of 40 remaining environmental areas of concern (AoCs) on the North American Great Lakes that have one or more water, habitat, or sediment quality impairments as defined by the International Joint Commission. In situ natural capping using sediment from to-be-remediated watersheds and other potential sources is being considered as the most feasible means of remediating an existing contaminated sediment problem at this site. A multi-decade (˜40 year) sediment budget shows that, when localized anthropogenic effects (dredging, reclamation) are discounted, the bay net-accumulated sediment over time. Sediment was supplied from three major sources: bank erosion and bluff retreat (41%), streams (25%), and the Lake Erie littoral system (20%). The non-stream sources supply environmentally clean materials from ancient beach and glacio-lacustrine deposits along the shoreline, and from the modern littoral system. Organic and metallic contaminants supplied primarily by streams and run-off remain a remediation challenge for the AoC. Geologically, natural capping of contaminants over the next several decades is a viable solution for most of the bay. The mechanism may not work effectively in all areas because approximately 25% of the bay floor is moderately net-erosional while several localized areas accumulate sediments very slowly at decadal timescales.

  3. THE RELATIONSHIP OF MOTILE DIATOMS TO ESTIMATES OF SEDIMENTATION IN STREAMS IN THE WESTERN LAKE SUPERIOR BASIN

    EPA Science Inventory

    Because certain motile diatoms are known to be asociated with sediments, we examined the relationship of the diatom assemblages in streams of the Western Lake Superior basin to estimates of sedimentation.

  4. Particle-associated contaminants in street dust, parking lot dust, soil, lake-bottom sediment, and suspended and streambed sediment, Lake Como and Fosdic Lake watersheds, Fort Worth, Texas, 2004

    USGS Publications Warehouse

    Wilson, Jennifer T.; Van Metre, Peter C.; Werth, Charles J.; Yang, Yanning

    2006-01-01

    A previous study by the U.S. Geological Survey of impaired water bodies in Fort Worth, Texas, reported elevated but variable concentrations of particle-associated contaminants (PACs) comprising chlorinated hydrocarbons, polycyclic aromatic hydrocarbons, and trace elements in suspended and bed sediment of lakes and streams affected by urban land use. The U.S. Geological Survey, in cooperation with the City of Fort Worth, collected additional samples during October 2004 to investigate sources of PACs in the watersheds of two impaired lakes: Lake Como and Fosdic Lake. Source materials and aquatic sediment were sampled and analyzed for PACs. Source materials sampled consisted of street dust and soil from areas with residential and commercial land use and parking lot dust from sealed and unsealed parking lots. Aquatic sediment sampled consisted of bottom-sediment cores from the two lakes and suspended and streambed sediment from the influent stream of each lake. Samples were analyzed for chlorinated hydrocarbons (organochlorine pesticides and polychlorinated biphenyls), polycyclic aromatic hydrocarbons, major and trace elements, organic carbon, grain size, and radionuclides.

  5. [Microbial biomass and its correlations with carbon, nitrogen, and phosphorus in the sediments of Taihu Lake].

    PubMed

    Wang, Na; Xu, De-Lin; Guo, Xuan; Wu, Xiao-Qing; An, Shu-Qing

    2012-07-01

    To explore the responses and feedbacks of the microbes in the sediments of Taihu Lake to the sediment nutrients, an investigation was made on the microbial biomass carbon (MB(C)), microbial biomass nitrogen (MB(N)), microbial biomass phosphorus (MB(P)), and their correlations with the total organic carbon (TOC), total nitrogen (TN), and total phosphorus (TP) in the sediments. The microbial biomass in the sediments was 184.66 mg x kg(-1), being higher at the lakeside than in the mid-lake region. The MB(C) was higher in the western coastal region, Zhushan Bay, and Meiliang Bay, with an average of 127.57 mg x kg(-1), MB(N) was higher in Meiliang Bay, Gonghu Bay, mid-lake region close to Meiliang Bay and Gonghu Bay, and eastern costal region, with an average of 19.25 mg x kg(-1), and MB(P) was higher in the eastern region and parts of the mid-lake region, with an average was 19.09 mg x kg(-1). The TOC high value zone (> or = 2.30 g x kg(-1)) was mainly in Zhushan Bay, western coastal region, Meiliang Bay, and Gonghu Bay, with an average of 1.59 g x kg(-1), TN high value zone (> or = 0.30 g x kg(-1)) was mainly in the Gonghu Bay, Meiliang Bay, Zhushan Bay, and western costal region, with an average of 0.21 g x kg(-1), and TP high value zone (> or = 1.20 g x kg(-1)) was mainly in the eastern coastal region and parts of the mid-lake region, with an average of 0.55 g x kg(-1). The TOC/TN ratio in the sediments was 7-19, with an average of 8.97, which showed that the organic substances in the sediments had obvious dual sources, among which, terrestrial organisms were mainly in the west side of the lake. The microbial biomass in the sediments was significantly positively correlated with sediment TOC and TN but had less correlation with sediment TP, and the MB(C)/MB(N) was significantly correlated with sediment TOC/TN, suggesting that the microbes in the sediments of Taihu Lake were mainly affected by the sediment TOC and TN, and the changes of the TOC/TN had significant

  6. Estimation of sediment sources using selected chemical tracers in the Perry lake basin, Kansas, USA

    USGS Publications Warehouse

    Juracek, K.E.; Ziegler, A.C.

    2009-01-01

    The ability to achieve meaningful decreases in sediment loads to reservoirs requires a determination of the relative importance of sediment sources within the contributing basins. In an investigation of sources of fine-grained sediment (clay and silt) within the Perry Lake Basin in northeast Kansas, representative samples of channel-bank sources, surface-soil sources (cropland and grassland), and reservoir bottom sediment were collected, chemically analyzed, and compared. The samples were sieved to isolate the <63 ?? m fraction and analyzed for selected nutrients (total nitrogen and total phosphorus), organic and total carbon, 25 trace elements, and the radionuclide cesium-137 (137Cs). On the basis of substantial and consistent compositional differences among the source types, total nitrogen (TN), total phosphorus (TP), total organic carbon (TOC), and 137Cs were selected for use in the estimation of sediment sources. To further account for differences in particle-size composition between the sources and the reservoir bottom sediment, constituent ratio and clay-normalization techniques were used. Computed ratios included TOC to TN, TOC to TP, and TN to TP. Constituent concentrations (TN, TP, TOC) and activities (137Cs) were normalized by dividing by the percentage of clay. Thus, the sediment-source estimations involved the use of seven sediment-source indicators. Within the Perry Lake Basin, the consensus of the seven indicators was that both channel-bank and surface-soil sources were important in the Atchison County Lake and Banner Creek Reservoir subbasins, whereas channel-bank sources were dominant in the Mission Lake subbasin. On the sole basis of 137Cs activity, surface-soil sources contributed the most fine-grained sediment to Atchison County Lake, and channel-bank sources contributed the most fine-grained sediment to Banner Creek Reservoir and Mission Lake. Both the seven-indicator consensus and 137Cs indicated that channel-bank sources were dominant for

  7. Phosphorus mobility among sediments, water and cyanobacteria enhanced by cyanobacteria blooms in eutrophic Lake Dianchi.

    PubMed

    Cao, Xin; Wang, Yiqi; He, Jian; Luo, Xingzhang; Zheng, Zheng

    2016-12-01

    This study was focused on the phosphorus mobility among sediments, water and cyanobacteria in eutrophic Lake Dianchi. Four conditions lake water, water and algae, water and sediments, and three objects together were conducted to investigate the effects of cyanobacteria growth on the migration and transformation of phosphorus. Results showed a persistent correlation between the development of cyanobacterial blooms and the increase of soluble reactive phosphorus (SRP) in the lake water under the condition of three objects together. Time-course assays measuring different forms of phosphorus in sediments indicated that inorganic phosphorus (IP) and NaOH-P were relatively more easier to migrate out of sediment to the water and cyanobacteria. Further studies on phosphorus mobility showed that up to 70.2% of the released phosphorus could be absorbed by cyanobacteria, indicating that sediment is a major source of phosphorus when external loading is reduced. Time-course assays also showed that the development of cyanobacterial blooms promoted an increase in pH and a decrease in the redox potential of the lake water. The structure of the microbial communities in sediments was also significantly changed, revealed a great impaction of cyanobacterial blooms on the microbial communities in sediments, which may contribute to phosphorus release. Our study simulated the cyanobacterial blooms of Lake Dianchi and revealed that the cyanobacterial blooms is a driving force for phosphorus mobility among sediments, water and cyanobacteria. The outbreak of algal blooms caused deterioration in water quality. The P in the sediments represented a significant supply for the growth of cyanobacteria.

  8. Origin of polycyclic aromatic hydrocarbons in lake sediments of the Mackenzie Delta.

    PubMed

    Headley, John V; Marsh, Philip; Akre, Christine J; Peru, Kerry M; Lesack, Lance

    2002-08-01

    The concentrations and distribution of polycyclic aromatic hydrocarbons (PAHs) were assessed in sediment cores from among 14 lakes from three regions comprising a transect across the central Mackenzie Delta. PAHs were consistently found in the lake sediments, with parent concentrations in the 20-200 ng/g range. Concentrations were generally independent of depth in the sediment cores and this pattern was similar among the 3 regions of the delta. Concentrations increased in a westerly direction among the regions. For some lakes, the concentration of PAHs decreased with decreasing flooding frequency, and decreasing sedimentation rates. For the latter, maximum concentrations occurred at shallower depths within the sediment cores as flooding frequency among the lakes decreased. The distributions of C0-C4 alkylated 2- and 3- ring PAHs were consistent with a petrogenic origin, while the corresponding distribution of 4-ring PAHs appears to be more consistent with a biogenic or pyrogenic origin. Based on relative contributions to the overall PAH budget, a petrogenic source appears to be dominant. However, the pyrene/fluoranthene ratio is more consistent with a source derived from peat. The alkylated PAH profiles are inconsistent with those in the Athabasca River system, and supports a previously published hypothesis that the contribution of PAHs from the Athabasca oil sands to the lower Mackenzie River is minimal. A double ratio plot of chrysene vs dibenzothiophene, diagnostic of weathering, suggests most weathering occurred before the sediments were deposited in the lakes, while a double ratio plot of dibenzothiophene vs phenanthrene suggests a common source of PAHs across the delta, despite differing water sources from east to west across the delta. PAH inputs to the delta appear to mirror sediment inputs documented in previous work, where high sediment input from the Mackenzie mainstem during high floods dominates the delta sediment influx and masks any influence of the

  9. Factors contributing to the internal loading of phosphorus from anoxic sediments in six Maine, USA, lakes.

    PubMed

    Lake, Bjorn A; Coolidge, Kyle M; Norton, Stephen A; Amirbahman, Aria

    2007-02-15

    Phosphorus (P) is the limiting macronutrient for primary production in most lakes. Seasonal anoxia in the hypolimnion of lakes has been strongly correlated with internal P loading to the water column. Gravimetric sediment cores were collected before and after the onset of anoxia in six Maine (USA) lakes during the summer of 2003. This study investigates the relative importance of P sequestration by aluminum hydroxide (Al(OH)3(s)), and ferric (oxy)hydroxide (Fe(OH)3(S)) dissolution with subsequent P release in lakes with varying trophic status. Two lakes, Pennesseewassee and Highland, are oligotrophic. The remaining lakes, China, Cobbosseecontee, Webber and Salmon, have varying levels of productivity. Sediment P, Al and Fe in the top 10 cm were extracted sequentially using ammonium chloride (NH4Cl), bicarbonate-dithionite (BD), and sodium hydroxide (NaOH) at 25 degrees C. The results suggest that a sediment [NH4Cl-Al+BD-Al+NaOH25-Al]:[NH4Cl-Fe+BD-Fe] molar ratio >3 and a sediment [NaOH25-Al]:[NH4Cl-P+BD-P] molar ratio >25 predict low P flux from sediments during the development of anoxia, as proposed by Kopácek et al. [Kopácek J, Borovec J, Hejzlar J, Ulrich K, Norton S, Amirbahman A. Aluminum control of Phosphorus Sorption in Lake Sediments. Environ Sci Technol 2005; 39: 8784-8789.], despite the development of anoxia in and the release of Fe(II) from the hypolimnia of the two study lakes. However, when these molar ratios are not exceeded the model does not adequately describe sedimentary P flux. The application of the model proposed by Kopácek et al. to Cobbosseecontee Lake suggests that its sediment may be a source of P to the water column. However, water column data indicate little to no sedimentary P flux. Therefore, the lack of P flux may be attributed to the absence of Fe(III) reduction in the Cobbosseecontee Lake sediment or perhaps to the slow diagenesis of organically-bound P.

  10. Sediment Characteristics of a High-Mountain Lake in South Central Anatolia, Turkey

    NASA Astrophysics Data System (ADS)

    Ataselim, Zeynep; Leroy, Suzanne; Gurbuz, Alper; Gurbuz, Esra; Onur Yucel, Tahsin; Yedek, Ozgur; Koc, Koray

    2016-04-01

    Lake Dipsiz is at the top of Mount Erenler, located 55 km west of Konya city in Central Anatolia, Turkey. Mount Erenler is the largest part of Central Anatolia Volcanic Province and consists of Miocene-Pliocene calc-alkaline lavas together with pyroclastic rocks and covers an area approximately 2000 km2. The peak of the Mount Erenler is at 1900 m while Lake Dipsiz is located at 1600 m altitude. Despite the small surface area (0.33 km2), the depth is relatively high (16 m). The drainage area of the lake is 8 km2. Although the topography of the lake points out to glacier presence, it formed as a landslide-dammed lake. Lake Dipsiz geographically is between mountainous Mediterranean region and Central Anatolia plateau. Climatically, the lake is in a transition zone between Taurids and Central Anatolia. In this study, we investigated sedimentation in a high altitude lake at a climatic transition. For this purpose, three cores (D1, D2 and D3) which are 50 cm length are taken with a hand corer from the coastline of the lake. D1 and D2 cores are sampled in every 2 cm and D3 core is samples in every 1 cm. Geochemical, total organic carbon, magnetic susceptibility and total carbonate analyses were performed on all sample sets. Lake sediments are brownish/green clay and silt in composition. Despite the proximity of the sediment source, no sand or more coarse grains were observed in the sedimentary filling. Organic matter content is between 2 - 28 %. According to one 14C date, the sequence indicates a Late Holocene age. δ13C isotope values are between -28.9 and -25.3 ‰ and it means that the sediment composed of terrestrial C3 organic matter. The detrital input in the lake has increased in the last 1000 years. Sedimentation rate was low between 3000 and cal. 1700 BP to the contrary of significant increasing from 250 BP to nowadays. Our data show that the sedimentation in this high altitude lake is more sensitive to other environmental conditions rather than climate.

  11. Physical processes in Subglacial Lake Whillans, West Antarctica: Inferences from sediment cores

    NASA Astrophysics Data System (ADS)

    Hodson, T. O.; Powell, R. D.; Brachfeld, S. A.; Tulaczyk, S.; Scherer, R. P.

    2016-06-01

    The hydrologic system beneath the Antarctic Ice Sheet is thought to influence both the dynamics and distribution of fast flowing ice streams, which discharge most of the ice lost by the ice sheet. Despite considerable interest in understanding this subglacial network and its affect on ice flow, in situ observations from the ice sheet bed are exceedingly rare. Here we describe the first sediment cores recovered from an active subglacial lake. The lake, known as Subglacial Lake Whillans, is part of a broader, dynamic hydrologic network beneath the Whillans Ice Stream in West Antarctica. Even though "floods" pass through the lake, the lake floor shows no evidence of erosion or deposition by flowing water. By inference, these floods must have insufficient energy to erode or transport significant volumes of sediment coarser than silt. Consequently, water flow beneath the region is probably incapable of incising continuous channels into the bed and instead follows preexisting subglacial topography and surface slope. Sediment on the lake floor consists of till deposited during intermittent grounding of the ice stream following flood events. The fabrics within the till are weaker than those thought to develop in thick deforming beds suggesting subglacial sediment fluxes across the ice plain are currently low and unlikely to have a large stabilizing effect on the ice stream's grounding zone.

  12. Mapping of accumulated nitrogen in the sediment pore water of a eutrophic lake in Iowa, USA

    USGS Publications Warehouse

    Iqbal, M.Z.; Fields, C.L.

    2009-01-01

    A large pool of nitrogen in the sediment pore fluid of a eutrophic lake in Iowa, USA, was mapped in this study. Previously, the lake had supported fishing and boating, but today it no longer supports its designated uses as a recreational water body. In the top 5 cm of the lake bottom, the pore water nitrogen ranges between 3.1 and 1,250 ??g/cm3 of sediments, with an average of 160.3 ??g/cm3. Vertically, nitrate concentrations were measured as 153 ??g/cm3 at 0-10 cm, 162 ??g/cm3 at 10-20 cm, and 32 ??g/cm3 at 20-30 cm. Nitrate mass distribution was quantified as 3.67 ?? 103 kg (65%) in the bottom sediments, 172 kg (3%) in suspended particulates, and 1.83 ?? 103 kg (32%) in the dissolved phase. Soil runoff nutrients arrive at the lake from the heavily fertilized lands in the watershed. Upon sedimentation, a large mass of nitrogen desorbs from mineral particles to the relatively immobile pore fluid. Under favorable conditions, this nitrogen diffuses back into the water column, thereby dramatically limiting the lake's capability to process incoming nutrients from farmlands. Consequently, a condition of oxygen deficiency disrupts the post-season biological activities in the lake. ?? 2008 Springer-Verlag.

  13. Persistent toxic substances in remote lake and coastal sediments from Svalbard, Norwegian Arctic: levels, sources and fluxes.

    PubMed

    Jiao, Liping; Zheng, Gene J; Minh, Tu Binh; Richardson, Bruce; Chen, Liqi; Zhang, Yuanhui; Yeung, Leo W; Lam, James C W; Yang, Xulin; Lam, Paul K S; Wong, Ming H

    2009-04-01

    Surface sediments from remote lakes and coastal areas from Ny-Alesund, Svalbard, Norwegian Arctic were analyzed for polycyclic aromatic hydrocarbons (PAHs), polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs). Relatively high levels of PAHs were encountered from several lakes from Ny-Alesund, which were within the range of levels reported for European high mountain lakes and some urban/industrialized areas in the world, pointing to the role of remote Arctic lakes as potential reservoir of semi-volatile organic compounds. Specific patterns of PBDEs were observed, showing higher concentrations of lower brominated compounds such as BDE-7, 17 and 28. Estimated surface sediment fluxes of PAHs in Ny-Alesund remote lakes were similar to those observed for some European high mountain lakes. The current PAH levels in sediments from three lakes exceeded Canadian sediment quality guidelines, suggesting the presence of possible risks for aquatic organisms and the need for further studies.

  14. Water-quality trends in suburban Houston, Texas, 1954-97, as indicated by sediment cores from Lake Houston

    USGS Publications Warehouse

    Van Metre, P.C.; Sneck-Fahrer, D. A.

    2002-01-01

    Water-quality trends were assessed in Lake Houston using age-dated sediment cores. Sediments deposited in the lake contain a partial chemical signature of human activities in the watershed. Over time, a water-quality history is recorded in the bottom sediments. Although the sediments in Lake Houston are clean compared to sediment-quality guidelines, increasing concentrations of mercury, zinc, and polycyclic aromatic hydrocarbons (PAHs) during the past several decades are evidence of the increasing human effect on water quality. The positive effects of regulation are indicated by decreases in concentrations of lead and DDT.

  15. Contaminant residues in fish and sediments from lakes in the Atchafalaya River Basin (Louisiana)

    USGS Publications Warehouse

    Winger, P.V.; Andreasen, J.K.

    1985-01-01

    Conversion of bottomland hardwood forests agricultural land has reduced habitat and water quality in many lakes in the floodplain of the lower Mississippi River. The objectives of this study were to ascertain current contaminant residue concentrations in fish and sediment from lakes in the Atchafalaya River Basin and to determine the influence of overflow and agricultural land use on contaminant levels. Fish and sediment samples were collected from eight lakes that differed in overflow (no overflow, headwater overflow, backwater overflow) and land-use characteristics (presence or absence of agricultural land). Residue analysis of 24 sediment and 82 fish samples collected from the study lakes showed that contaminant residues were uniformly low. Total DDT concentrations, consisting mainly of DDE, were found in 98% of the fish samples and generally were the highest residues though they rarely exceeded 0.50 ug/g. Dieldrin, -BHC and -BHC, in concentrations rarely exceeding 0.05 ug/g, were detected in about 50% of the fish samples. Total organochlorine pesticide and PCB residues were less than 2.00 ug/g in all fish from all lakes, except for a 3.46 ug/g total in spotted gar (Lepisosteus oculatus) from one lake. Sediments were free from pesticide residues except for occasional traces (0.01 ug/g) of -BHC. Metal residue concentrations in fish and sediment samples were typical of uncontaminated areas. Lake systems in the Atchafalaya River Basin appeared to be relatively uncontaminated by agricultural pesticides, but metal and organic residues in fish were similar from lakes with the same land-use and overflow characteristics.

  16. Modeled tephra ages from lake sediments, base of Redoubt Volcano, Alaska

    SciTech Connect

    Schiff, C J; Kaufman, D S; Wallace, K L; Werner, A; Ku, T L; Brown, T A

    2007-02-25

    A 5.6-m-long lake sediment core from Bear Lake, Alaska, located 22 km southeast of Redoubt Volcano, contains 67 tephra layers deposited over the last 8750 cal yr, comprising 15% of the total thickness of recovered sediment. Using 12 AMS {sup 14}C ages, along with the {sup 137}Cs and {sup 210}Pb activities of recent sediment, we evaluated different models to determine the age-depth relation of sediment, and to determine the age of each tephra deposit. The age model is based on a cubic smooth spline function that was passed through the adjusted tephra-free depth of each dated layer. The estimated age uncertainty of the 67 tephras averages {+-} 105 yr (1{sigma}). Tephra-fall frequency at Bear Lake was among the highest during the past 500 yr, with eight tephras deposited compared to an average of 3.7 per 500 yr over the last 8500 yr. Other periods of increased tephra fall occurred 2500-3500, 4500-5000, and 7000-7500 cal yr. Our record suggests that Bear Lake experienced extended periods (1000-2000 yr) of increased tephra fall separated by shorter periods (500-1000 yr) of apparent quiescence. The Bear Lake sediment core affords the most comprehensive tephrochronology from the base of the Redoubt Volcano to date, with an average tephra-fall frequency of once every 130 yr.

  17. Phosphorus speciation of sediments from lakes of different tropic status in Eastern China.

    PubMed

    Zhang, Wenqiang; Rong, Nan; Jin, Xin; Li, Jie; Ding, Yuekui; Zhu, Xiaolei; Shan, Baoqing

    2016-04-01

    Information about the chemical composition of phosphorus (P) in sediment is critical for understanding P dynamics and eutrophication in lake ecosystems. Eutrophication as a result of P pollution still persists so we chose to determine the P characteristics of sediments from ten lakes of different trophic status and the relationships between P fractions and environmental factors. The results show that the Standards, Measurements and Testing (SMT) method combined with (31)P-nuclear magnetic resonance ((31)P-NMR) can efficiently show the P characteristics of sediment. Phosphorus concentrations in sediments decreased as the trophic status of the lake improved. Inorganic P (Pi) was the dominant form of total P (TP) in most of the lake sediments and was mainly comprised of HCl-Pi, a stable Pi fraction. Results of (31)P-NMR analysis show that the extracts were dominated by ortho-P (36.4-94.8%) and mono-P (4.0-36.2%), with smaller amounts of diester-P (.6-23.1%), pyro-P (.2-4.4%), and phon-P (.3-.7%). Analysis of the relationships between the P composition and the trophic status of the lakes indicated that the bioavailability of P forms has an influence on the surface water trophic conditions and the health of aquatic ecosystems.

  18. Effects of algae growth on cadmium remobilization and ecological risk in sediments of Taihu Lake.

    PubMed

    Ni, Lixiao; Li, Dandan; Su, Lili; Xu, Jiajun; Li, Shiyin; Ye, Xiang; Geng, Hong; Wang, Peifang; Li, Yi; Li, Yiping; Acharya, Kumud

    2016-05-01

    Indoor simulation experiment with 2.76 L microcosms using sediment from Taihu Lake were conducted to investigate the relationship between algae bloom and heavy metals release into a lake aquatic environment. The results showed that Microcystic aeruginosa (M. aeruginosa) growth can enhance cadmium (Cd) mobilization from sediments to overlying water due to increasing pH and DO content of overlying water and changing the redox condition of surface sediment (0-2 cm) from weak oxidation to weak reduction. The dissolved Cd concentration in overlying water can be decreased during algal growth process. The remobilization of Cd from sediment can effectively reduce the ecological risk of total Cd in sediments. The results of this study showed that both Igeo and Er(i) can be used to effectively evaluate the ecological risk of heavy metal Cd in different fractions.

  19. Methane sources in arctic thermokarst lake sediments on the North Slope of Alaska.

    PubMed

    Matheus Carnevali, P B; Rohrssen, M; Williams, M R; Michaud, A B; Adams, H; Berisford, D; Love, G D; Priscu, J C; Rassuchine, O; Hand, K P; Murray, A E

    2015-03-01

    The permafrost on the North Slope of Alaska is densely populated by shallow lakes that result from thermokarst erosion. These lakes release methane (CH4 ) derived from a combination of ancient thermogenic pools and contemporary biogenic production. Despite the potential importance of CH4 as a greenhouse gas, the contribution of biogenic CH4 production in arctic thermokarst lakes in Alaska is not currently well understood. To further advance our knowledge of CH4 dynamics in these lakes, we focused our study on (i) the potential for microbial CH4 production in lake sediments, (ii) the role of sediment geochemistry in controlling biogenic CH4 production, and (iii) the temperature dependence of this process. Sediment cores were collected from one site in Siqlukaq Lake and two sites in Sukok Lake in late October to early November. Analyses of pore water geochemistry, sedimentary organic matter and lipid biomarkers, stable carbon isotopes, results from CH4 production experiments, and copy number of a methanogenic pathway-specific gene (mcrA) indicated the existence of different sources of CH4 in each of the lakes chosen for the study. Analysis of this integrated data set revealed that there is biological CH4 production in Siqlukaq at moderate levels, while the very low levels of CH4 detected in Sukok had a mixed origin, with little to no biological CH4 production. Furthermore, methanogenic archaea exhibited temperature-dependent use of in situ substrates for methanogenesis, and the amount of CH4 produced was directly related to the amount of labile organic matter in the sediments. This study constitutes an important first step in better understanding the actual contribution of biogenic CH4 from thermokarst lakes on the coastal plain of Alaska to the current CH4 budgets.

  20. Varve deposition and the sediment yield record at three small lakes of the southern Canadian Cordillera

    SciTech Connect

    Desloges, J.R. )

    1994-05-01

    Lacustrine sediments deposited in three small glacier-fed lakes of the southern Canadian Cordillera are derived primarily from subglacial erosion and delivered via short proglacial streams or by direct melting and calving of cirque glaciers. Sediment transport and deposition during early summer is controlled by runoff-generated bottom currents and in the late summer through winter by settling from suspension. This forms distinct rhythmic laminations of silt and clay in distal lake areas. Cesium-137 content in all three lakes indicates that these are varve sediments. Time series of varve thickness covering the interval 1863 to present show distinct declines in sediment yield from 310 to less than 150 t km[sup [minus]2] a[sup [minus]1]. The decline is related to sediment exhaustion following glacier retreat from Little Ice Age maxima and the opening of intervening sediment storage sites. Annual varve thickness is significantly related to fluctuations in summer or late summer temperature highlighting the importance of ice ablation, melt-water runoff, and subglacial sediment sources in controlling deposition rates. Singular climate events, such as autumn storms provide distinctive sedimentary signatures in the varve record. Reconstructed sediment yield for the Little Ice Age is as much as 100% greater than the average Holocene rate. 39 refs., 8 figs., 2 tabs.

  1. Bottom sediment as a source of organic contaminants in Lake Mead, Nevada, USA.

    PubMed

    Alvarez, David A; Rosen, Michael R; Perkins, Stephanie D; Cranor, Walter L; Schroeder, Vickie L; Jones-Lepp, Tammy L

    2012-07-01

    Treated wastewater effluent from Las Vegas, Nevada and surrounding communities' flow through Las Vegas Wash (LVW) into the Lake Mead National Recreational Area at Las Vegas Bay (LVB). Lake sediment is a likely sink for many hydrophobic synthetic organic compounds (SOCs); however, partitioning between the sediment and the overlying water could result in the sediment acting as a secondary contaminant source. Locating the chemical plumes may be important to understanding possible chemical stressors to aquatic organisms. Passive sampling devices (SPMDs and POCIS) were suspended in LVB at depths of 3.0, 4.7, and 6.7 (lake bottom) meters in June of 2008 to determine the vertical distribution of SOCs in the water column. A custom sediment probe was used to also bury the samplers in the sediment at depths of 0-10, 10-20, and 20-30cm. The greatest number of detections in samplers buried in the sediment was at the 0-10cm depth. Concentrations of many hydrophobic SOCs were twice as high at the sediment-water interface than in the mid and upper water column. Many SOCs related to wastewater effluents, including fragrances, insect repellants, sun block agents, and phosphate flame retardants, were found at highest concentrations in the middle and upper water column. There was evidence to suggest that the water infiltrated into the sediment had a different chemical composition than the rest of the water column and could be a potential risk exposure to bottom-dwelling aquatic organisms.

  2. First Feedbacks on Restored Floodplain Lakes Sedimentation along the Rhône River

    NASA Astrophysics Data System (ADS)

    Michalkova, M.; Piegay, H.

    2009-04-01

    Sedimentation rates and processes were studied in eighteen restored floodplain lakes and channels of the Rhône River in south-eastern France. Whilst many authors have studied the sedimentation in former channels before restoration, little is known about post-restoration sedimentation rates and processes since these are only now becoming evident. The objective of study was therefore to evaluate the variability in post-restoration habitat conditions inside of floodplain lakes (inter-lake comparison) and to consider the temporal evolution of habitat conditions. The increase of the minimum discharge in the old Rhône channel and the removal of sediments in the floodplain lakes were the main issues of the Rhône River restoration project. In addition, the minimum discharge increase resulted in a higher water-table in the former Rhône channel. The sediment survey protocol was established and three steps were implemented: i) the measurement of the sedimentation rates based on the ratio between the mean sediment thickness and the time since the restoration works; ii) determination of connection discharge by piezometers and precise DGPS survey and iii) the statistical analysis of the relationships and inter-lake analysis (the characterization of connection frequency and to define the life expectancy of former channels). Changes in the connectivity between the main channel and other aquatic zones also influence the change in sedimentation rate through time. Multiple parameters such as age, channel geometry, mean annual sediment supply and frequency of connection, groundwater connection with the main channel and the type of sediments (sand, clay, silt, gravel) are included. The variability is in the inter-lakes function of restored reaches along the length of the Rhone corridor. Three hydro-geomorphological groups can be identified: 1. Systems characterized by rapid flows and the transport of sand and fine sediment (YEN, LUI, CIS) 2. Systems characterized by a wide range of

  3. Characteristics of bioavailable organic phosphorus in sediment and its contribution to lake eutrophication in China.

    PubMed

    Ni, Zhaokui; Wang, Shengrui; Wang, Yuemin

    2016-12-01

    This study aims to establish the relative importance of sediment organic phosphorus (Po) to the total P and the major classes of organic molecules that contribute to sediment Po, determined by measuring their susceptibility to enzymatic hydrolysis, across a suite of lakes ranging from oligotrophic to eutrophic status. The results showed that Po accounted for 21-60% of total P, and bioavailable Po accounted for 9-34% of Po in the sediments. The bioavailable Po includes mainly labile (H2O-Po) and moderately labile (NaOH-Po) P forms. For H2O-Po (accounting for only1.4% of Po), 53% (average) was labile monoester P, 28% was diester P and 17% was phytate-like P. For NaOH-Po (accounting for 9-33% of Po), 32% was labile monoester P, 33% was phytate-like P and 18% was diester P. The composition of bioavailable Po, determined by enzyme assays, was related to the lake nutrient levels, which implies that sediment bioavailable Po could act as an effective indicator for lake eutrophic status. With the increase of lake nutrient levels, bioavailable Po content and alkaline phosphatase activity in the sediment all increased, indicating that Po represents an important and bioavailable source of P that increases with eutrophication, and could contribute to internal loading and resistance of eutrophic lakes to remediation. This implies that eutrophic lakes would maintain long-term eutrophic status and algal bloom phenomena even after the external input of P was controlled and the total P concentration of water has declined. Thus, in order to reduce the release risk of sediment P more efficiently and effectively, sediment P control technique should focus not only on reducing the total P and inorganic P, but should also pay close attention to the removal of bioavailable Po.

  4. Modern sedimentation patterns in Laguna de Medina, Southern Spain, derived from lake surface and soil samples

    NASA Astrophysics Data System (ADS)

    van ´t Hoff, Jasmijn; Schröder, Tabea; Reicherter, Klaus; Held, Peter; Melles, Martin

    2016-04-01

    In September 2014 and March 2015, a 25.66 m long sediment core (Co1313) was retrieved from the centre of Laguna de Medina, a small endorheic salt lake in Cádiz, SW Spain. This record covers the last 9.000 years, thus providing an unique archive for Holocene climatic and environmental changes with extraordinary high temporal resolution. For a better understanding of the palaeoenvironmental proxies to be analysed on the sediment core, the modern processes of sediment formation in the lake and its catchment under known environmental conditions were investigated on a set of 46 lake sediment surface samples and 32 soil surface sediment samples from the lake and the close surroundings, respectively. These samples were analysed for bulk mineralogy (XRD), chemical composition (XRF), grain-size distribution (laser scanner), and carbonate, total organic carbon (TOC), nitrogen (TN) and sulphur (TS) contents (elemental analyser). Based on the mineralogical, geochemical and granulometrical data, the lake can be divided into four zones. The northern shore is characterized by particularly high quartz contents and coarse grain sizes. This reflects input from ancient terraces of the Guadalete River that are exposed in that area. The southern shore is characterised by high calcite contents due to sediment supply from the Cretaceous ´Capas rojaś, a series of Subbetic deep-water marl- and limestones. The southeastern and to a lesser extend the northwestern shores show particularly high dolomite contents, reflecting the Triassic dolomites outcroping in the southeastern catchment. The southeastern shore furthermore is also influenced by strong terrestrial input of the Triassic Keuper facies from the most important inlet, Arroyo Fuente Bermeja, as reflected by high contents of Ti, K, Al, Fe, Rb in the lake sediments. The last zone comprises only a small part of the western shore and is characterized by a relatively high gypsum amount. This does not reflect the geology in the catchment

  5. [Bioavailability of dissolved organic nitrogen components in the lake sediment to alage].

    PubMed

    Feng, Wei-Ying; Zhang, Sheng; Jiao, Li-Xin; Wang, Sheng-Rui; Li, Chang-You; Cui, Feng-Li; Fu, Xu-Jin; Zhen, Zhi-Lei

    2013-06-01

    Samples in the sediments of Wuliangsuhai and Erhai Lake were selected, and the technologies of XAD-8 resins separation and three dimensional fluorescence excitation-emission matrix (3DEEM) spectra were applied, in order to study the bioavailability of dissolved organic nitrogen components to alage under the room cultivation. The obtained results showed that: (1) Average loss of DON and DOC from sediments was below 5% after dividing DON into different groups, which means the technology of XAD- 8 resins separation could be used in the study of DON components in the lake sediment. (2) Through 3DEEM analysis, hydrophilic and hydrophobic DON was dominated by protein-like and humic-like materials in the lake sediment, respectively. (3) Under the hydrophilic component condition, growth curves of algae tended to show an "S" shape with a straight upward trend in the sediments of Wuliangsuhai and Erhai lake,with the maximum algal density reaching 535.5 x 10(4) and 709.5 x 10(4) per milliliter, respectively. Meanwhile, the DON concentrations were significantly reduced after cultivation to 2.46 and 2.98 mg x L(-1), respectively, which suggests that hydrophilic DON in the lake sediment was the bioavailable organic nitrogen for alage. (4) Under the hydrophbic component conditions, growth curves of algae tended to show a "unimodal" shape in the sediments of Wuliangsuhai and Erhai lake,with the maximum algal density reaching 113.5 x 10(4) and 275.5 x 10(4) per milliliter,respectively. The DON concentrations were significantly reduced during the early cultivation period, and then kept stable in the late period, which suggests that the hydrophobic DON component bioavailable to alage was low in short-term, and the hydrophobic DON component had hardly any positive effect on the growth of algae.

  6. Jellyfish Lake, Palau: Regeneration of C, N, Si, and P in anoxic marine lake sediments

    USGS Publications Warehouse

    Lyons, W.B.; Lent, R.M.; Burnett, W.C.; Chin, P.; Landing, W.M.; Orem, W.H.; McArthur, J.M.

    1996-01-01

    Sediment cores from Jellyfish Lake were processed under an inert atmosphere and the pore waters extracted and analyzed for the following parameters: pH, titration alkalinity (TA), Cl-, H4SiO4, PO43-, NH4+, Ca2-, Mg2+, SO42-, and H2S. Additionally, in one set of pore-water samples (core 10), the ??13C of the ??CO2 was also determined. The TA, H4SiO4, PO43-, NH4+, and H2S increased with depth in the pore waters above anoxic bottom-water values. H2S values increased to 3.8 ??M. In one case, both H4SiO4 and PO43- concentrations increased to a maximum value and then decreased with depth, suggesting removal into solid phases. The H4SiO4 concentrations are equal to or greater than pore-water values observed in sediments underlying upwelling areas. PO43- concentrations are, in general, lower than pore-water values from terrigenous nearshore areas but higher than nearshore carbonate pore-water values from Florida Bay or Bermuda. The Ca2+, Cl-, and Mg2+: Cl- ratios show slight decreases in the top 15-20 cm, suggesting that authigenic carbonate may be forming. This suggestion is supported by the fact that the pore waters are saturated with respect to CaCO3 due to the very high TAs. The ??13C measurements of the pore-water ??CO2 are from a shorter core. These measurements reach their most negative concentration at 72 cm and then become slightly heavier. This change is accompanied by a decrease in TA, suggesting the onset of methanogenesis at this location in this core.

  7. Hexabromocyclododecane Flame Retardant Isomers in Sediments from Detroit River and Lake Erie of the Laurentian Great Lakes of North America.

    PubMed

    Letcher, Robert J; Lu, Zhe; Chu, Shaogang; Haffner, G Douglas; Drouillard, Ken; Marvin, Christopher H; Ciborowski, Jan J H

    2015-07-01

    Sediments collected in 2004 from along the Detroit River (n = 19) and across all of Lake Erie (n = 18) were analyzed for isomers of the flame retardant chemical, hexabromocyclododecane (HBCD), using liquid chromatography-tandem mass spectrometry. Sediment samples had ΣHBCD concentrations ranging from not detected to 1.6 ng/g d.w. γ-HBCD (56 %-100 % of ΣHBCDs) was the predominate isomer, observed in 7 of 19 samples from the Detroit River and 6 of 18 samples from Lake Erie (all within the western basin). α-HBCD was found in 4 Detroit River and 2 Lake Erie western basin sites, while β-HBCD was only in two Detroit River samples. High ΣHBCD concentrations (>100 ng/g d.w.) were found in two sludge samples from two Windsor, ON, wastewater treatment plants that feed into the Detroit River upstream. HBCD contamination into the Detroit River is a major input vector into Lake Erie and with an apparent sediment dilution effect moving towards the eastern basin.

  8. Spatiotemporal patterns of mercury accumulation in lake sediments of western North America

    USGS Publications Warehouse

    Drevnick, Paul; Cooke, Colin A.; Barraza, Daniella; Blais, Jules M.; Coale, Kenneth; Cumming, Brian F.; Curtis, Chris; Das, Biplob; Donahue, William F.; Eagles-Smith, Collin A.; Engstrom, Daniel R.; Fitzgerald, William F.; Furl, Chad V.; Gray, John R.; Hall, Roland I.; Jackson, Togwell A.; Laird, Kathleen R.; Lockhart, W. Lyle; Macdonald, Robie W.; Mast, M. Alisa; Mathieu, Callie; Muir, Derek C.G.; Outridge, Peter; Reinemann, Scott; Rothenberg, Sarah E.; Ruiz-Fernandex, Ana Carolina; St. Louis, V.L.; Sanders, Rhea; Sanei, Hamed; Skierszkan, Elliott; Van Metre, Peter C.; Veverica, Timothy; Wiklund, Johan A.; Wolfe, Brent B.

    2016-01-01

    For the Western North America Mercury Synthesis, we compiled mercury records from 165 dated sediment cores from 138 natural lakes across western North America. Lake sediments are accepted as faithful recorders of historical mercury accumulation rates, and regional and sub-regional temporal and spatial trends were analyzed with descriptive and inferential statistics. Mercury accumulation rates in sediments have increased, on average, four times (4×) from 1850 to 2000 and continue to increase by approximately 0.2 μg/m2 per year. Lakes with the greatest increases were influenced by the Flin Flon smelter, followed by lakes directly affected by mining and wastewater discharges. Of lakes not directly affected by point sources, there is a clear separation in mercury accumulation rates between lakes with no/little watershed development and lakes with extensive watershed development for agricultural and/or residential purposes. Lakes in the latter group exhibited a sharp increase in mercury accumulation rates with human settlement, stabilizing after 1950 at five times (5×) 1850 rates. Mercury accumulation rates in lakes with no/little watershed development were controlled primarily by relative watershed size prior to 1850, and since have exhibited modest increases (in absolute terms and compared to that described above) associated with (regional and global) industrialization. A sub-regional analysis highlighted that in the ecoregion Northwestern Forest Mountains, <1% of mercury deposited to watersheds is delivered to lakes. Research is warranted to understand whether mountainous watersheds act as permanent sinks for mercury or if export of “legacy” mercury (deposited in years past) will delay recovery when/if emissions reductions are achieved.

  9. Spatiotemporal patterns of mercury accumulation in lake sediments of western North America.

    PubMed

    Drevnick, Paul E; Cooke, Colin A; Barraza, Daniella; Blais, Jules M; Coale, Kenneth H; Cumming, Brian F; Curtis, Chris J; Das, Biplob; Donahue, William F; Eagles-Smith, Collin A; Engstrom, Daniel R; Fitzgerald, William F; Furl, Chad V; Gray, John E; Hall, Roland I; Jackson, Togwell A; Laird, Kathleen R; Lockhart, W Lyle; Macdonald, Robie W; Mast, M Alisa; Mathieu, Callie; Muir, Derek C G; Outridge, Peter M; Reinemann, Scott A; Rothenberg, Sarah E; Ruiz-Fernández, Ana Carolina; Louis, Vincent L St; Sanders, Rhea D; Sanei, Hamed; Skierszkan, Elliott K; Van Metre, Peter C; Veverica, Timothy J; Wiklund, Johan A; Wolfe, Brent B

    2016-10-15

    For the Western North America Mercury Synthesis, we compiled mercury records from 165 dated sediment cores from 138 natural lakes across western North America. Lake sediments are accepted as faithful recorders of historical mercury accumulation rates, and regional and sub-regional temporal and spatial trends were analyzed with descriptive and inferential statistics. Mercury accumulation rates in sediments have increased, on average, four times (4×) from 1850 to 2000 and continue to increase by approximately 0.2μg/m(2) per year. Lakes with the greatest increases were influenced by the Flin Flon smelter, followed by lakes directly affected by mining and wastewater discharges. Of lakes not directly affected by point sources, there is a clear separation in mercury accumulation rates between lakes with no/little watershed development and lakes with extensive watershed development for agricultural and/or residential purposes. Lakes in the latter group exhibited a sharp increase in mercury accumulation rates with human settlement, stabilizing after 1950 at five times (5×) 1850 rates. Mercury accumulation rates in lakes with no/little watershed development were controlled primarily by relative watershed size prior to 1850, and since have exhibited modest increases (in absolute terms and compared to that described above) associated with (regional and global) industrialization. A sub-regional analysis highlighted that in the ecoregion Northwestern Forest Mountains, <1% of mercury deposited to watersheds is delivered to lakes. Research is warranted to understand whether mountainous watersheds act as permanent sinks for mercury or if export of "legacy" mercury (deposited in years past) will delay recovery when/if emissions reductions are achieved.

  10. Rock Magnetic Detection of Two Coercivity Components of Magnetosomes in Lake Ely Sediments

    NASA Astrophysics Data System (ADS)

    Kodama, K. P.; Chen, A.; Egli, R.; Vavrek, J.

    2007-12-01

    The modeling of IRM acquisition curves has become an important tool used by environmental magnetists to characterize a sample's magnetic mineralogy. We have applied IRM modeling to lake sediments from Lake Ely, a small, post-glacial lake located in northeastern Pennsylvania. The lake is unique in having a strong sedimentary magnetization dominated by the magnetosomes produced by magnetotactic bacteria. Measurements of Fe, S, and O2 at different depths in the lake's water column, as well as the magnetization of material filtered from the water, indicate that magnetotactic bacteria live in the water column at the oxic-anoxic interface. Magnetic measurements and TEM observations of lake sediments and material caught in a sediment trap indicate that magnetosomes are the major constituent of the magnetic minerals in the lake sediments. IRM modeling shows two separate coercivity components at about 30 mT and 60 mT that are consistent with Egli's (2004) observations of BS (biogenic soft) and BH (biogenic hard) coercivity components for magnetosomes in lake sediments. However, the peaks are poorly determined because only 6-7 data points constrain the 0-100 mT part of the IRM coercivity spectrum. We used pARMs (97 μT DC field) applied in 5 mT alternating field steps between 0 and 100 mT to better resolve the BH and BS coercivity peaks. pARM spectra collected from lake sediment samples reveal one strong coercivity peak at approximately 30 mT in the 0-100 mT range. A second higher coercivity peak at about 80 mT is weakly evident in some samples. Alternating field demagnetization in 104 steps of an ARM applied to one sample also suggests the presence of two coercivity peaks but at 20 and 40 mT. First order reversal curves (FORCs) measured at the Institute for Rock Magnetism show that the magnetic grains behave as non-interacting single domain grains, implying that the magnetosome chains are relatively far apart and probably still intact. The FORC diagrams also show a large

  11. Disentangling Holocene lake level changes with a transect of lake sediment cores - a case study from Lake Fürstenseer See, northeastern Germany

    NASA Astrophysics Data System (ADS)

    Dietze, Elisabeth; Slowinski, Michal; Kienel, Ulrike; Zawiska, Izabela; Brauer, Achim

    2014-05-01

    Deciphering the main processes contributing to lake and landscape evolution in the northern central European lowlands on different temporal scales is one of the main targets of the Virtual Institute of Integrated Climate and Landscape Evolution Analysis (ICLEA) of the Helmholtz Association. In the context of future climatic changes especially the hydrological system is a vulnerable landscape component that showed considerably large changes in the recent past. The analysis of lake sediment archives can help to infer long-term dynamics of regional lake and groundwater levels, although available proxy information needs to be studied carefully, as water level changes are only one trigger. Lake Fürstenseer See (53°19'N, 13°12'E, lake level in 2009: 63.3 m a.s.l.) formed after the retreat of the Weichselian ice sheet in a subglacial channel in the direct forefront of the Pommerian ice margin. The ~2 km2 large lake (zmax = 24.5 m) has a (sub-) surficial catchment area of ~(20) 40 km2 including other smaller lakes and peatlands. In the past, the lake system was artificially dammed for the operation of water mills. Located within the well-drained sandur substrate, the lake levels vary with groundwater levels in response to hydrological and catchment-related groundwater recharge. Detrital matter input from fluvial activity can be excluded. Lake sediment cores at four sites along a transect down to 23 m water depth show distinct sediment facies patterns. Stratigraphic descriptions and non-destructive continuous micro-XRF scanning allowed the differentiation of the main sediment facies, which were microscopically described using thin sections. Quantification of total organic and inorganic matter (TOC, TIC, C/N-composition) and discontinuous macrorest, diatom and Cladocera analysis helped to approach the sedimentation history. Stable isotopes of (delta-180, delta-13C) were used for characterization of carbonates. A high amount of non-reworked terrestrial plant remains from

  12. Effects of sample mass and macrofossil type on radiocarbon dating of arctic and boreal lake sediments

    SciTech Connect

    Oswald, W W; Anderson, P M; Brown, T A; Brubaker, L B; Hu, F S; Lozhkin, A V; Tinner, W; Kaltenrieder, P

    2006-05-29

    Dating lake sediments by accelerator mass spectrometry (AMS) {sup 14}C analysis of plant macrofossils overcomes one of the main problems associated with dating bulk sediment samples, the presence of old organic matter. Even so, many AMS dates from arctic and boreal sites appear to misrepresent the age of the sediment. To understand the nature of these apparent dating anomalies better, we conducted a series of {sup 14}C dating experiments using samples from Alaskan and Siberian lake-sediment cores. First, to test whether our analytical procedures introduced a sample-mass bias, we obtained {sup 14}C dates for different-sized pieces of single woody macrofossils. In these sample-mass experiments, sized statistically equivalent ages were found for samples as small as 0.05 mg C. Second, to assess whether macrofossil type influenced dating results, we conducted sample-type experiments in which {sup 14}C dates were obtained for different macrofossil types sieved from the same depth in the sediment. We dated materials from multiple levels in sediment cores from Upper Capsule Lake (North Slope, northern Alaska) and Grizzly Lake (Copper River Basin, southern Alaska), and from single depths in other records from northern Alaska. In several of the experiments there were significant discrepancies between dates for different plant tissues, and in most cases wood and charcoal were older than other macrofossil types, usually by several hundred years. This pattern suggests that {sup 14}C dates for woody macrofossils may misrepresent the age of the sediment by centuries, perhaps due to their longer terrestrial residence time and the potential in-built age of long-lived plants. This study identifies why some {sup 14}C dates appear to be inconsistent with the overall age-depth trend of a lake-sediment record, and it may guide the selection of {sup 14}C samples in future studies.

  13. Identification of contamination in a lake sediment core using Hg and Pb isotopic compositions, Lake Ballinger, Washington, USA

    USGS Publications Warehouse

    Gray, John E.; Pribil, Michael J.; Van Metre, Peter C.; Borrok, David M.; Thapalia, Anita

    2013-01-01

    Concentrations and isotopic compositions of Hg and Pb were measured in a sediment core collected from Lake Ballinger, near Seattle, Washington, USA. Lake Ballinger has been affected by input of metal contaminants emitted from the Tacoma smelter, which operated from 1887 to 1986 and was located about 53 km south of the lake. Concentrations and loadings of Hg and Pb in Lake Ballinger increased by as much as three orders of magnitude during the period of smelting as compared to the pre-smelting period. Concentrations and loadings of Hg and Pb then decreased by about 55% and 75%, respectively, after smelting ended. Isotopic compositions of Hg changed considerably during the period of smelting (δ202Hg = −2.29‰ to −0.38‰, mean −1.23‰, n = 9) compared to the pre-smelting period (δ202Hg = −2.91‰ to −2.50‰, mean −2.75‰, n = 4). Variations were also observed in 206Pb/207Pb and 208Pb/207Pb isotopic compositions during these periods. Data for Δ199Hg and Δ201Hg indicate mass independent fractionation (MIF) of Hg isotopes in Lake Ballinger sediment during the smelting and post-smelting period and suggest MIF in the ore smelted, during the smelting process, or chemical modification at some point in the past. Negative values for Δ199Hg and Δ201Hg for the pre-smelting period are similar to those previously reported for soil, peat, and lichen, likely suggesting some component of atmospheric Hg. Variations in the concentrations and isotopic compositions of Hg and Pb were useful in tracing contaminant sources and the understanding of the depositional history of sedimentation in Lake Ballinger.

  14. Historical trends of inorganic and organic fluorine in sediments of Lake Michigan.

    PubMed

    Codling, Garry; Vogt, Anja; Jones, Paul D; Wang, Tieyu; Wang, Pei; Lu, Y-L; Corcoran, Margaret; Bonina, Solidea; Li, An; Sturchio, Neil C; Rockne, Karl J; Ji, Kyunghee; Khim, Jong-Seong; Naile, Jonathan E; Giesy, John P

    2014-11-01

    Total fluorine (TF), extractable organic fluorine (EOF) and poly- and per-fluorinated compounds (PFCs) were measured in eight dated cores of sediment taken along with 27 surface sediments from Lake Michigan in 2010. Based on rates of sedimentation, total concentrations of PFCs (∑PFCs) reached a maximum in the later 1990s and early 2000s. This result is consistent with rapid changes in production and subsequent sedimentation. Perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) are still the predominant PFCs in the cores, but in surface sediments, concentrations of perfluorobutane sulfonate (PFBS) and perfluorobutanoic acid (PFBA) are now occurring at concentrations comparable to those of PFOS and PFOA. This observation is consistent with shifts in patterns of production and use in the US and Canada. Concentrations of TF in sediments were greater than those of EOF. This result is consistent with a larger proportion of un-extractable fluorinated material in both surface sediments and in cores.

  15. 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

  16. Chemical contamination and physical characteristics of sediments in the upper Great Lakes connecting channels 1985

    USGS Publications Warehouse

    Bertram, Paul E.; Edsall, Thomas A.; Manny, Bruce A.; Nichols, Susan J.; Schloesser, Donald W.

    1991-01-01

    Contamination of sediments by toxic organic substances and heavy metals was widespread throughout the connecting channels of the upper Great Lakes in 1985. Sediments at 250 stations in the connecting channels were analyzed for total PCBs, oil and grease, phenols, total cyanide, total volatile solids, mercury, cadmium, chromium, cobalt, copper, lead, nickel, and zinc, and the results were evaluated according to U.S. EPA guidelines for polluted sediments. Sediments were most heavily contaminated near industrialized areas, although some areas more than 40 km downstream from known point sources of pollution were moderately contaminated by oil and metals.

  17. Late Pleistocene/Holocene paleoclimate reconstruction and eruptive history of Central American volcanoes from lake bottom sediments of Lake Nicaragua

    NASA Astrophysics Data System (ADS)

    Wulf, S.; Dull, R. A.; Mann, P.; McIntosh, K. D.; Gardner, J. E.

    2007-12-01

    A shallow coring program in Lake Nicaragua was completed in May/June 2006 by the University of Texas (UT Department of Geography and UT Institute for Geophysics). A total of 35 sediment cores with lengths ranging between 12 cm and 100 cm along with five longer cores were extracted from the lake using a gravity corer and a modified manual square rod piston corer, respectively. Analyses of lake sediments have the following objectives: 1) to correlate the geophysical results with the core data to provide a stratigraphic framework for the shallow lake sediments; 2) to constrain past climate variability in this rather poorly investigated area; and 3) to establish a time series of explosive volcanic activity based on the identification and dating of tephra layers in the cores. Initial measurements of magnetic susceptibility, dry density, loss on ignition and XRF scanning indicated a dominance of fine-grained homogeneous diatomaceous sediments cover most of the lake floor. Increasing values in magnetic susceptibility in the upper part of several short cores most likely reflect increased erosion caused by land-use changes during the Spanish colonial period (1522-1822). Results on the two longest cores from the northeastern (355 cm) and southwestern (478 cm) parts of the lake reveal complete Holocene paleoclimate records in both areas that are comparable to other terrestrial and marine records in the Central and South- American tropics (i.e. Cariaco Basin). A lithologic change from homogeneous gyttia (diatomaceous mud) to blue- grayish waxy clay at the bottom of these records marks the Late Pleistocene-Holocene transition as indicated by a radiocarbon dating on plant remains. The latter dense clay forms a distinctive stratigraphic marker in the lake basin. Tephra layers to date were detected in most gravity cores recovered west of Ometepe Island (Volcan Concepcion), and in long records in the northeastern basin (San Antonio Tephra, Masaya volcano, ca. 7,400 interpolated cal

  18. Mercury pollution in the lake sediments and catchment soils of anthropogenically-disturbed sites across England.

    PubMed

    Yang, Handong; Turner, Simon; Rose, Neil L

    2016-12-01

    Sediment cores and soil samples were taken from nine lakes and their catchments across England with varying degrees of direct human disturbance. Mercury (Hg) analysis demonstrated a range of impacts, many from local sources, resulting from differing historical and contemporary site usage and management. Lakes located in industrially important areas showed clear evidence for early Hg pollution with concentrations in sediments reaching 400-1600 ng g(-1) prior to the mid-19th century. Control of inputs resulting from local management practices and a greater than 90% reduction in UK Hg emissions since 1970 were reflected by reduced Hg pollution in some lakes. However, having been a sink for Hg deposition for centuries, polluted catchment soils are now the major Hg source for most lakes and consequently recovery from reduced Hg deposition is being delayed.

  19. Spatial variation on inorganic sediment and implications for human-induced trace metal loading at Lake Louise, Georgia

    SciTech Connect

    Hyatt, J.A.; Ekstrom, N.F.; Tepper, J.H.

    1997-09-01

    Near-surface sediments within Lake Louise, Georgia, form a 15 to 20 cm thick layer of light gray sediment that is enriched relative to underlying sediment in inorganics and trace metals. This enrichment has been attributed to the influx of elastic sediments to the lake during construction of near-by Interstate 75 in 1957. This study examines the spatial variability of inorganic sediment within this surface layer (SL). Our purposes are: (1) to infer controls on sedimentation, (2) to estimate how much sediment and metal has entered the lake because of highway construction, and (3) to discuss implications of observed spatial trends to trace metal loading in the lake. The middle (M) and top (T) sample groups are statistically indistinguishable from one another. However, the bottom sample group (B) has significantly higher inorganic sediment content, dry bulk density, and lower moisture content than the combined M-T sample group. In addition, simple linear regression indicates a statistically significant trend of increasing inorganic content with increasing water depth. This trend likely reflects an initial focussing of construction-derived clastic sediment into the deepest parts of the lake by turbidity flows. Subsequent bioturbation and a diminished post-construction influx of sediment to the lake may be responsible for the reduced focussing trend apparent in the M-T sample group. Using these trends together with bathymetric data we estimate between 7.1 and 10.1 x 10{sup 5} kg of dry sediment and significant quantities of trace metals (e.g. 6540 kg Ti, 270 kg Ba, 60 kg Pb) were introduced to the lake by highway construction. In addition the majority of trace metals reside within the inorganic sediment fraction. Consequently, the observed focussing of inorganic sediment to the deep parts of the lake basin implies a similar concentration in trace-metals within Lake Louise.

  20. Anomalous plutonium isotopic ratios in sediments of Lake Qinghai from the Qinghai-Tibetan Plateau, China.

    PubMed

    Wu, Fengchang; Zheng, Jian; Liao, Haiqing; Yamada, Masatoshi; Wan, Guojiang

    2011-11-01

    The vertical profiles of (239+240)Pu and (137)Cs activities and (240)Pu/(239)Pu isotopic ratios are determined for three sediment cores of Lake Qinghai from the Qinghai-Tibetan Plateau, China, and compared with those in sediments of another three lakes (Lakes Bosten, Sugan, and Shuangta), the only existing ones closest to Lop Nor area, China's nuclear weapons test site in the northwestern part of the country. The mean inventory of 47.7 ± 18.7 MBq km(-2) for (239+240)Pu activity in Lake Qinghai is comparable to the average value of global fallout expected at the same latitude, yet the mean inventory of 1112.0 ± 78.0 MBq km(-2) for (137)Cs is slightly lower than that of global fallout. Anomalously low (240)Pu/(239)Pu isotopic ratios (0.038-0.125) were found in the 3-6.5 cm deep sediment layers, indicating the trace Pu input from early nuclear weapons research activities at Atomic City in the lake's watershed during the 1950-60s. Model calculation indicated that the Pu input accounted for approximately 5-16% of the total Pu inventory. The observation of low (240)Pu/(239)Pu ratio in the deep sediment layer provided a new time marker for recent sediment dating in the lake and around the area. The results are of great significance to the further understanding of sources, records, and environmental impacts of global and regional nuclear activities in the environment and provide important chronological information for further studies on the water eutrophication process and climatic change, and reconstruction of pollution history of organic contaminants and heavy metals in the watershed of Lake Qinghai.

  1. Sorption coefficients of polycyclic aromatic hydrocarbons for two lake sediments: Influence of the bactericide sodium azide

    SciTech Connect

    Maagd, P.G.J. de; Sinnige, T.L.; Schrap, S.M.; Opperhuizen, A.; Sijm, D.T.H.M.

    1998-10-01

    Sorption coefficient s (K{sub p}s) of a series of polycyclic aromatic hydrocarbons (PAHs) were determined in two Dutch freshwater lake sediments to improve the insight into sorption in the aquatic environment. The influence of experimental factors, such as compound concentration, equilibration time, and influence of a bactericide on K{sub p}, was studied. No significant influence of compound concentration on K{sub p} was found. A contact time of 48 h was sufficient to reach equilibrium between PAHs in the sediment and water phase. In the absence of the bactericide, sodium azide, incomplete mass balances, and high K{sub p} of low molecular weight PAHs were found that were not caused by volatilization from, photodegradation in, or sorption by the test system. In the presence of sodium azide, however, high mass balances and lower K{sub p} were found for these compounds. This suggested that significant biodegradation of these compounds occurred in the water phase in the absence of sodium azide. The organic carbon-normalized sorption coefficients (K{sub oc}) of the PAHs in Lake Oostvaardersplassen were two to three times higher than those in Lake Ketelmeer sediment. Although K{sub oc} of the PAHs differed for the two sediments, a clear relationship was found between K{sub oc} and the octanol/water partition coefficient for both sediments and between the K{sub oc} of both sediments. In conclusion, the methodology to determine K{sub p} of biodegradable compounds should include the prevention of bacterial activity, e.g., by addition of sodium azide. Sorption of PAHs in the Dutch lake sediments is determined by the hydrophobicity of the PAH, the organic carbon content of the sediment, and one or more unspecified sediment-specific characteristics.

  2. Bottom sediment as a source of organic contaminants in Lake Mead, Nevada, USA

    USGS Publications Warehouse

    Alvarez, David A.; Rosen, Michael R.; Perkins, Stephanie D.; Cranor, Walter L.; Schroeder, Vickie L.; Jones-Lepp, Tammy L.

    2012-01-01

    Treated wastewater effluent from Las Vegas, Nevada and surrounding communities' flow through Las Vegas Wash (LVW) into the Lake Mead National Recreational Area at Las Vegas Bay (LVB). Lake sediment is a likely sink for many hydrophobic synthetic organic compounds (SOCs); however, partitioning between the sediment and the overlying water could result in the sediment acting as a secondary contaminant source. Locating the chemical plumes may be important to understanding possible chemical stressors to aquatic organisms. Passive sampling devices (SPMDs and POCIS) were suspended in LVB at depths of 3.0, 4.7, and 6.7 (lake bottom) meters in June of 2008 to determine the vertical distribution of SOCs in the water column. A custom sediment probe was used to also bury the samplers in the sediment at depths of 0–10, 10–20, and 20–30 cm. The greatest number of detections in samplers buried in the sediment was at the 0–10 cm depth. Concentrations of many hydrophobic SOCs were twice as high at the sediment–water interface than in the mid and upper water column. Many SOCs related to wastewater effluents, including fragrances, insect repellants, sun block agents, and phosphate flame retardants, were found at highest concentrations in the middle and upper water column. There was evidence to suggest that the water infiltrated into the sediment had a different chemical composition than the rest of the water column and could be a potential risk exposure to bottom-dwelling aquatic organisms.

  3. Thirty-year trends in suspended sediment in seven Lake Erie tributaries.

    PubMed

    Richards, R Peter; Baker, David B; Crumrine, John P; Kramer, Jack W; Ewing, D Ellen; Merryfield, Barbara J

    2008-01-01

    Sediment is an important pollutant for Lake Erie and its tributaries as a carrier of other substances and as a pollutant in its own right. Environmental managers have called for major reductions in sediment loadings in Lake Erie tributaries. In this study, 30-yr (1975-2005) datasets with daily resolution are analyzed to identify and interpret trends in sediment concentrations and loads in major US tributaries to Lake Erie. The Maumee and Sandusky Rivers in agricultural northwest Ohio show continual decreases throughout this period, but the River Raisin shows increases, especially in the last decade. The urban and forested Cuyahoga River shows little trend before 2000 but shows increases since then. The mostly forested Grand River shows strong decreases before 1995, little change thereafter until the early 2000s, and then increases. In most cases, the greatest decreases or smallest increases, depending on the river, are associated with summer and fall and with low flow conditions, whereas the smallest decreases or greatest increases are associated with the spring and with high flow conditions. Analysis of concentration-flow relationships indicates that these changes are not due to weather but reflect positive and negative anthropogenic influences. Sediment decreases in the northwestern Ohio tributaries seem to reflect the successful use of agricultural practices to reduce erosion and prevent sediment loss. Opportunities for further reductions in sediment loads and concentrations lie in better management of sediment losses during winter and spring.

  4. Metal impacts on microbial biomass in the anoxic sediments of a contaminated lake

    SciTech Connect

    Gough, Heidi L.; Dahl, Amy L.; Nolan, Melissa A.; Gaillard, Jean-Francois; Stahl, David A.

    2008-04-26

    Little is known about the long-term impacts of metal contamination on the microbiota of anoxic lake sediments. In this study, we examined microbial biomass and metals (arsenic, cadmium, chromium, copper, iron, lead, manganese, and zinc) in the sediments of Lake DePue, a backwater lake located near a former zinc smelter. Sediment core samples were examined using two independent measures for microbial biomass (total microscopic counts and total phospholipid-phosphate concentrations), and for various fractions of each metal (pore water extracts, sequential extractions, and total extracts of all studied metals and zinc speciation by X-ray absorption fine structure (XAFS). Zinc concentrations were up to 1000 times higher than reported for sediments in the adjacent Illinois River, and ranged from 21,400 mg/kg near the source to 1,680 mg/kg near the river. However, solid metal fractions were not well correlated with pore water concentrations, and were not good predictors of biomass concentrations. Instead, biomass, which varied among sites by as much as two-times, was inversely correlated with concentrations of pore water zinc and arsenic as established by multiple linear regression. Monitoring of other parameters known to naturally influence biomass in sediments (e.g., organic carbon concentrations, nitrogen concentrations, pH, sediment texture, and macrophytes) revealed no differences that could explain observed biomass trends. This study provides strong support for control of microbial abundance by pore water metal concentrations in contaminated freshwater sediments.

  5. Nitrate attenuation potential of hypersaline lake sediments in central Spain: flow-through and batch experiments.

    PubMed

    Carrey, R; Rodríguez-Escales, P; Otero, N; Ayora, C; Soler, A; Gómez-Alday, J J

    2014-08-01

    Complex lacustrine systems, such as hypersaline lakes located in endorheic basins, are exposed to nitrate (NO3(-)) pollution. An excellent example of these lakes is the hypersaline lake located in the Pétrola basin (central Spain), where the lake acts as a sink for NO3(-) from agricultural activities and from sewage from the surrounding area. To better understand the role of the organic carbon (Corg) deposited in the bottom sediment in promoting denitrification, a four-stage flow-through experiment (FTR) and batch experiments using lake bottom sediment were performed. The chemical, multi-isotopic and kinetic characterization of the outflow showed that the intrinsic NO3(-) attenuation potential of the lake bottom sediment was able to remove 95% of the NO3(-) input over 296days under different flow conditions. The NO3(-) attenuation was mainly linked with denitrification but some dissimilatory nitrate reduction to ammonium was observed at early days favored by the high C/N ratio and salinity. Sulfate reduction could be neither confirmed nor discarded during the experiments because the sediment leaching masked the chemical and isotopic signatures of this reaction. The average nitrogen reduction rate (NRR) obtained was 1.25mmold(-1)kg(-1) and was independent of the flow rate employed. The amount of reactive Corg from the bottom sediment consumed during denitrification was 28.8mmol, representing approximately 10% of the total Corg of the sediment (1.2%). Denitrification was produced coupled with an increase in the isotopic composition of both δ(15)N and δ(18)O. The isotopic fractionations (ε of (15)N-NO3(-) and (18)O-NO3(-)) produced during denitrification were calculated using batch and vertical profile samples. The results were -14.7‰ for εN and -14.5‰ for εO.

  6. Reconstructing a long-term record of microcystins from the analysis of lake sediments.

    PubMed

    Zastepa, A; Taranu, Z E; Kimpe, L E; Blais, J M; Gregory-Eaves, I; Zurawell, R W; Pick, F R

    2017-02-01

    Based on an analysis of sediment cores from Baptiste Lake (Alberta, Canada), we quantified century-scale trends in cyanobacteria and cyanotoxins, and identified possible drivers of toxigenic cyanobacteria. We measured concentrations of microcystins and pigments preserved in the sediment as proxies of toxigenic cyanobacteria and phytoplankton communities, respectively, while fossil diatom assemblages were used to infer past nutrient concentrations. Microcystins were detected in older sediments (ca. 1800s), pre-dating any significant alteration to the watershed. This demonstrates that toxigenic cyanobacteria may not be a recent phenomenon in eutrophic ecosystems. The dominant variants of microcystin throughout the sediment core were microcystin-LA and microcystin-LR. Other congeners including -LY, -7dmLR, -WR, -LF, -YR, and -LW (-RR was not detected) were mainly found in the upper layers of sediment (post 1980s). Starting in the 1990s, concentrations of microcystins both in the water column and in the sediment record increased in parallel. Total sediment microcystins were strongly correlated with historical nitrogen and phosphorus concentrations inferred from diatom assemblages (r=0.80-0.81, p<0.001, n=22); both nutrients increased over the past two decades coincident with the intensification of agriculture. Microcystins also tracked the rise in cyanobacterial pigments present throughout the core. In contrast, we found no relationship between climate-related variables and sediment microcystin concentrations, although such relationships were detected over the monitoring record with respect to water column concentrations. Overall, the rise in sediment microcystins was much greater than the rise in sediment cyanobacteria and diatom inferred nutrient concentrations. Furthermore, we demonstrate that the reconstruction of the microcystin sediment record can provide important insight for the development of realistic lake management goals. Applying this analytical approach

  7. Diversity of active aerobic methanotrophs along depth profiles of arctic and subarctic lake water column and sediments

    USGS Publications Warehouse

    He, Ruo; Wooller, Matthew J.; Pohlman, John W.; Quensen, John; Tiedje, James M.; Leigh, Mary Beth

    2012-01-01

    Methane (CH4) emitted from high-latitude lakes accounts for 2–6% of the global atmospheric CH4 budget. Methanotrophs in lake sediments and water columns mitigate the amount of CH4 that enters the atmosphere, yet their identity and activity in arctic and subarctic lakes are poorly understood. We used stable isotope probing (SIP), quantitative PCR (Q-PCR), pyrosequencing and enrichment cultures to determine the identity and diversity of active aerobic methanotrophs in the water columns and sediments (0–25 cm) from an arctic tundra lake (Lake Qalluuraq) on the north slope of Alaska and a subarctic taiga lake (Lake Killarney) in Alaska's interior. The water column CH4 oxidation potential for these shallow (~2m deep) lakes was greatest in hypoxic bottom water from the subarctic lake. The type II methanotroph, Methylocystis, was prevalent in enrichment cultures of planktonic methanotrophs from the water columns. In the sediments, type I methanotrophs (Methylobacter, Methylosoma and Methylomonas) at the sediment-water interface (0–1 cm) were most active in assimilating CH4, whereas the type I methanotroph Methylobacter and/or type II methanotroph Methylocystis contributed substantially to carbon acquisition in the deeper (15–20 cm) sediments. In addition to methanotrophs, an unexpectedly high abundance of methylotrophs also actively utilized CH4-derived carbon. This study provides new insight into the identity and activity of methanotrophs in the sediments and water from high-latitude lakes.

  8. 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

  9. 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...

  10. Depositional Influences on Porewater Arsenic in Sediments of a Mining-Contaminated Freshwater Lake

    SciTech Connect

    Toevs, G.; Morra, M.J.; Winowiecki, L.; Strawn, D.; Polizzotto, M.L.; Fendorf, S.

    2009-05-26

    Arsenic-containing minerals mobilized during mining activities and deposited to Lake Coeur d'Alene (CDA), Idaho sediments represent a potential source of soluble As to the overlying water. Our objective was to delineate the processes controlling porewater As concentrations within Lake CDA sediments. Sediment and porewater As concentrations were determined, and solid-phase As associations were probed using X-ray absorption near-edge structure (XANES) spectroscopy. Although maximum As in the sediment porewaters varied from 8.4 to 16.2 microM, As sorption on iron oxyhydroxides at the oxic sediment-water interface prevented flux to overlying water. Floods deposit sediment containing variable amounts of arsenopyrite (FeAsS), with majorfloods depositing large amounts of sediment that bury and preserve reduced minerals. Periods of lower deposition increase sediment residence times in the oxic zone, promoting oxidation of reduced minerals, SO4(2-) efflux, and formation of oxide precipitates. Depositional events bury oxides containing sorbed As, transitioning them into anoxic environments where they undergo dissolution, releasing As to the porewater. High Fe:S ratios limit the formation of arsenic sulfides in the anoxic zone. As a result of As sequestration at the sediment-water interface and its release upon burial, decreased concentrations of porewater As will not occur unless As-bearing erosional inputs are eliminated.

  11. Differences in the Composition of Archaeal Communities in Sediments from Contrasting Zones of Lake Taihu.

    PubMed

    Fan, Xianfang; Xing, Peng

    2016-01-01

    In shallow lakes, different primary producers might impact the physiochemical characteristics of the sediment and the associated microbial communities. Until now, little was known about the features of sediment Archaea and their variation across different primary producer-dominated ecosystems. Lake Taihu provides a suitable study area with cyanobacteria- and macrophyte-dominated zones co-occurring in one ecosystem. The composition of the sediment archaeal community was assessed using 16S rRNA gene amplicon sequencing technology, based on which the potential variation with respect to the physiochemical characteristics of the sediment was analyzed. Euryarchaeota (30.19% of total archaeal sequences) and Bathyarchaeota (28.00%) were the two most abundant phyla, followed by Crenarchaeota (11.37%), Aigarchaeota (10.24%) and Thaumarchaeota (5.98%). The differences found in the composition of the archaeal communities between the two zones was significant (p = 0.005). Sediment from macrophyte-dominated zones had high TOC and TN content and an abundance of archaeal lineages potentially involved in the degradation of complex organic compounds, such as the order Thermoplasmatales. In the area dominated by Cyanobacteria, archaeal lineages related to sulfur metabolism, for example, Sulfolobales and Desulfurococcales, were significantly enriched. Among Bathyarchaeota, subgroups MCG-6 and MCG-15 were significantly accumulated in the sediment of areas dominated by macrophytes whereas MCG-4 was consistently dominant in both type of sediments. The present study contributes to the knowledge of sediment archaeal communities with different primary producers and their possible biogeochemical functions in sediment habitats.

  12. Benthic sediment composition and nutrient cycling in an Intermittently Closed and Open Lake Lagoon

    NASA Astrophysics Data System (ADS)

    Spooner, D. R.; Maher, W.

    2009-01-01

    Surfical sediments within Corunna Lake, a moderate size Intermittently Closed and Open Lake Lagoon (ICOLL), were examined for solid phase nutrient concentrations (TN, TP, TOC,) and solute exchange rates between the sediment and water column (O 2, NO 3-N, NH 4-N, FRP, and N 2). The surfical sediments in Corunna Lake contained high concentrations of TN (5 mg/g dry mass), total phosphorus (0.6 mg/g dry mass), and TOC (~ 5% dry mass). The carbon stable isotope ratio ( δ13C) and TOC:TN ratios ( δ13C ~ - 24, TOC:TN ~ 11-14) demonstrated that the composition of the organic matter in the sediment was a mixture derived primarily of degraded planktonic matter. The close association between TP and Fe concentrations highlighted the potential role Fe plays in mediating Filterable Reactive Phosphorus (FRP) concentrations in the water column of Corunna Lake. In situ benthic chamber incubations were used to measure benthic fluxes. Solute exchange rates between the sediment and water column in Corunna Lake were similar to other reported studies (O 2 = - 469 to - 1765 µmol m - 2 h - 1, NH 4-N = 0.1-63 µmol m - 2 h - 1, NO 2/NO 3-N = 0 µmol m - 2 h - 1, FRP = - 4-1.6 µmol m - 2 h - 1and N 2 = 12-356 µmol m - 2 h - 1). As more carbon was deposited and mineralized the efficiency of the bacterial population to denitrify nitrogen in the sediment decreases. The linkage between land use and benthic biogeochemistry was also explored. A dairy farm exists in the middle catchment of Corunna Lake, and the receiving bay sediment consistently demonstrated the highest oxygen consumption rates in winter and spring (- 1408 µmol m - 2 h - 1 in winter, - 1691 µmol m - 2 h - 1 in spring) and lowest denitrification efficiencies during summer (~ 3%). Nitrate/nitrite fluxes were not observed during any of the chamber incubations, with the concentrations of nitrate/nitrite being below detection limits (< 10 μg/L). Seasonal changes influenced the rates of solute exchange between the sediment and

  13. Diploptene δ13C values from contemporary thermokarst lake sediments show complex spatial variation

    NASA Astrophysics Data System (ADS)

    Davies, Kimberley L.; Pancost, Richard D.; Edwards, Mary E.; Anthony, Katey M. Walter; Langdon, Peter G.; Chaves Torres, Lidia

    2016-05-01

    Cryospheric changes in northern high latitudes are linked to significant greenhouse gas flux to the atmosphere, for example, methane that originates from organic matter decomposition in thermokarst lakes. The set of pathways that link methane production in sediments, via oxidation in the lake system, to the flux of residual methane to the atmosphere is complex and exhibits temporal and spatial variation. The isotopic signal of bacterial biomarkers (hopanoids, e.g. diploptene) in sediments has been used to identify contemporary ocean-floor methane seeps and, in the geological record, periods of enhanced methane production (e.g. the PETM). The biomarker approach could potentially be used to assess temporal changes in lake emissions through the Holocene via the sedimentary biomarker record. However, there are no data on the consistency of the signal of isotopic depletion in relation to source or on the amount of noise (unexplained variation) in biomarker values from modern lake sediments. We assessed methane oxidation as represented by the isotopic signal of biomarkers from methane oxidising bacteria (MOB) in multiple surface sediment samples in three distinct areas known to emit varying levels of methane in two shallow Alaskan thermokarst lakes. Diploptene was present and had δ13C values lower than -38 ‰ in all sediments analysed, suggesting methane oxidation was widespread. However, there was considerable variation in δ13C values within each area. The most 13C-depleted diploptene was found in an area of high methane ebullition in Ace Lake (diploptene δ13C values between -68.2 and -50.1 ‰). In contrast, significantly higher diploptene δ13C values (between -42.9 and -38.8 ‰) were found in an area of methane ebullition in Smith Lake. δ13C values of diploptene between -56.8 and -46.9 ‰ were found in the centre of Smith Lake, where ebullition rates are low but diffusive methane efflux occurs. The small-scale heterogeneity of the samples may reflect patchy

  14. Modeled tephra ages from lake sediments, base of Redoubt Volcano, Alaska

    USGS Publications Warehouse

    Schiff, C.J.; Kaufman, D.S.; Wallace, K.L.; Werner, A.; Ku, T.-L.; Brown, T.A.

    2008-01-01

    A 5.6-m-long lake sediment core from Bear Lake, Alaska, located 22 km southeast of Redoubt Volcano, contains 67 tephra layers deposited over the last 8750 cal yr, comprising 15% of the total thickness of recovered sediment. Using 12 AMS 14C ages, along with the 137Cs and 210Pb activities of recent sediment, we evaluated different models to determine the age-depth relation of the core, and to determine the age of each tephra deposit. The selected age model is based on a mixed-effect regression that was passed through the adjusted tephra-free depth of each dated layer. The estimated age uncertainty of the 67 tephras averages ??105 yr (95% confidence intervals). Tephra-fall frequency at Bear Lake was among the highest during the past 500 yr, with eight tephras deposited compared to an average of 3.7/500 yr over the last 8500 yr. Other periods of increased tephra fall occurred 2500-3500, 4500-5000, and 7000-7500 cal yr. Our record suggests that Bear Lake experienced extended periods (1000-2000 yr) of increased tephra fall separated by shorter periods (500-1000 yr) of apparent quiescence. The Bear Lake sediment core affords the most comprehensive tephrochronology from the base of the Redoubt Volcano to date, with an average tephra-fall frequency of one every 130 yr. ?? 2007 Elsevier Ltd. All rights reserved.

  15. BIOGEOCHEMICAL CONTROLS ON REACTION OF SEDIMENTARY ORGANIC MATTER AND AQUEOUS SULFIDES IN HOLOCENE SEDIMENTS OF MUD LAKE FLORIDA

    EPA Science Inventory

    The distribution and quantity of organic sulfur and iron sulfur species were determined in the
    Holocene sediments from Mud Lake, Florida. The sediments of this shallow, sinkhole lake are characterized by high sulfur and organic carbon contents as well as active sulfate reducti...

  16. Response of sediment calcium and magnesium species to the regional acid deposition in eutrophic Taihu Lake, China.

    PubMed

    Tao, Yu; Dan, Dai; Chengda, He; Qiujin, Xu; Fengchang, Wu

    2016-11-01

    Acid deposition causes carbonate dissolution in watersheds and leads to profound impacts on water chemistry of lakes. Here, we presented a detailed study on the seasonal, spatial, and vertical variations of calcium and magnesium species in the overlying water, interstitial water, and sediment profiles in eutrophic Taihu Lake under the circumstance of regional acid deposition. The result showed that both the acid deposition and biomineralization in Taihu Lake had effects on Ca and Mg species. In the lake water, calcium carbonate was saturated or over-saturated based on long-term statistical calculation of the saturation index (SI). On the sediment profiles, significant difference in Ca and Mg species existed between the surface sediment (0-10 cm) and deeper sediments (>10 cm). The interstitial water Ca(2+) and Mg(2+), ion-exchangeable Ca and Mg in the surface sediment were higher than those in the deeper sediment. In the spring, when the acid deposition is more intensive, the acid-extracted Ca and Mg in the surface sediment were lower than that in the deeper sediment in the northwest lake, due to carbonate dissolution caused by the regional acid deposition. Spatially, the higher concentration of acid-extracted Ca and Mg in the northwest surface sediment than that in the east lake was observed, indicating the pronounced carbonate biomineralization by algae bloom in the northwest lake. Statistical analysis showed that acid deposition exerted a stronger impact on the variation of acid-extracted Ca and Mg in the surface sediment than the biomineralization in Taihu Lake. For the total Ca and Mg concentration in the spring, however, no significant change between the surface and deeper sediment in the northwest lake was observed, indicating that the carbonate precipitation via biomineralization and the carbonate dissolution due to acidic deposition were in a dynamic balance. These features are of major importance for the understanding of combined effects of acid

  17. Methane Concentrations and Biogeochemistry in Lake Sediments from Stordalen Mire, Sub-Arctic Sweden

    NASA Astrophysics Data System (ADS)

    Halloran, M.; DeStasio, J.; Erickson, L.; Johnson, J. E.; Varner, R. K.; Setera, J.; Prado, M. F.; Wik, M.; Crill, P. M.

    2013-12-01

    Lake sediments are an important global carbon sink of both allochthonous and autochthonous inputs. However, lakes are also known to emit carbon in gaseous form, most often as methane (CH4) or carbon dioxide (CO2), which are potent greenhouse gases. As northern latitudes warm, it is increasingly important to understand these gases and the sediments that store them. In July of 2013 we took 48 cores at 16 sites throughout three lakes surrounding a mire underlain by degrading permafrost in sub-arctic Sweden. The goal was to characterize the sedimentology and geochemistry of the lake sediments to better understand the production, distribution, and flux of CO2 and CH4 from these lakes. Villasjön is a shallow lake less than 1.5 meters deep, Mellan Harrsjön has a maximum depth of 7 meters and is stream-fed, and Inre Harrsjön has a maximum depth of 5 meters and is connected to Mellan Harrsjön. Published radiocarbon dates suggest that all three lakes formed approximately 3400 years ago. At each sample site, we retrieved 2 to 4 cores from the lake bottom, approximately 40-80 cm in length. The cores were sub-sampled for measurements of bulk TOC, TC, TN, TS, and CaCO3 (by difference) using a CHNS Elemental Analyzer, and grain size using a laser particle size analyzer. Headspace CO2 and CH4 by gas chromatography and infrared gas analysis (IRGA) yielded production rates and CH4 sediment concentrations. Dissolved inorganic carbon (DIC) from porewater extractions were analyzed using IRGA and stable carbon isotopes of DIC were analyzed via a Quantum Cascade Laser. The recovered sediments in the cores from all three lakes were composed of three layers: an upper layer of organic rich sediment (30-40 cm thick), a middle transition layer of mixed organic and lithogenic materials (5-10 cm thick), and a deep layer of grey lithogenic clay with less organic carbon (of variable thickness). Preliminary results from the 12 Villasjön sites indicate that CH4 is present and produced from the

  18. Environmental controls on branched tetraether lipid distributions in tropical East African lake sediments

    NASA Astrophysics Data System (ADS)

    Tierney, J. E.; Russell, J. M.; Eggermont, H.; Hopmans, E. C.; Verschuren, D.; Sinninghe Damsté, J. S.

    2010-09-01

    Quantifying past continental temperature changes is an important aspect of paleoclimate research as it allows us to constrain the amplitude of natural variability, test predictive climate models, and provide a proper context for changes that may arise in response to anthropogenically-induced climate change. The recently developed biomarker-based methylation index of branched tetraethers/cyclization ratio of branched tetraethers (MBT/CBT) proxy shows potential as a new method for continental temperature reconstruction, but thus far it has only been applied successfully in ocean margin sediments. To assess whether this proxy is also applicable to the sedimentary record in tropical lacustrine systems, we investigated the distribution of branched glycerol dialkyl glycerol tetraethers (GDGTs) in recently deposited sediments from 46 lakes in tropical East Africa. These lakes span a substantial range in surface elevation (770-4500 m above sea level), and thus also a wide gradient of mean annual temperature. We find that, saline lakes excepted, branched GDGTs are universally abundant in the lakes investigated and can be used to predict mean annual air temperature (MAAT) with a high degree of accuracy. However, the existing global MBT/CBT calibration for MAAT based on soils predicts inaccurate temperatures when applied to our African lake dataset. This observation, together with the fact that surface water pH, and to lesser extent, lake depth appear to influence the distribution of branched GDGTs among sites, leads us to conclude that in situ production of branched GDGTs in lakes is likely. The robust relationship between branched GDGT distribution and the temperature and pH of African freshwater lakes makes these compounds suitable for paleoenvironmental reconstruction, however we urge caution in using branched GDGTs in lake sediments to infer past temperatures, unless their exact origin can be determined.

  19. Microbial Diversity in Sediments of Saline Qinghia Lake, China:Linking Geochemical Controls to Microbial Ecoloby

    SciTech Connect

    Dong, Hailiang; Zhang, Gengxin; Jiang, Hongchen; Yu, Bingsong; Chapman, Leah R.; Lucas, Courtney R.; Fields, Matthew W.

    2007-03-30

    Saline lakes at high altitudes represent an important andextreme microbial ecosystem, yet little is known about microbialdiversity in such environments. The objective of this study was toexamine the change of microbial diversity from the bottom of the lake tosediments of 40 cm in depth in a core from Qinghai Lake. The lake issaline (12.5 g/L salinity) and alkaline (pH 9.4) and is located on theQinghai-Tibetan Plateau at an altitude of 3196 m above sea level. Porewater chemistry of the core revealed low concentrations of sulfate andiron (<1 mM), but high concentrations of acetate (40-70 mM) anddissolved organic carbon (1596-5443 mg/L). Total organic carbon and totalnitrogen contents in the sediments were approximately 2 and<0.5percent, respectively. Acridine orange direct count data indicated thatcell numbers decreased from 4 x 10(9) cells/g at the water-sedimentinterface to 6 x 10(7) cells/g wet sediment at the 40-cm depth. Thischange in biomass was positively correlated with acetate concentration inpore water. Phospholipid fatty acid (PLFA) community structure analysesdetermined decrease in the proportion of the Proteobacteria and increasein the Firmicutes with increased depth. Characterization of small subunit(SSU) rRNA genes amplified from the sediments indicated a shift in thebacterial community with depth. Whereas the alpha-, beta-, andgamma-Proteobacteria and the Cytophaga/Flavobacterium/Bacteroides (CFB)were dominant at the water-sediment interface, low G + C gram-positivebacteria (a subgroup of Firmicutes) became the predominant group in theanoxic sediments. Both PLFA and the sequence data showed similar trend.The Proteobacteria, CFB, and gram-positive bacteria are present in othersaline lakes, but the presence of Actinobacteria andAcidobacteria/Holophaga in significant proportions in the Qinghai Lakesediments appears to be unique. The archaeal diversity was much lower,and clone sequences could be grouped in the Euryarchaeota andCrenarchaeota domains. The

  20. Halogens in the Dry Valleys Lakes, Antarctica: dynamic cycling between water, sediment, and cryogenic evaporites

    NASA Astrophysics Data System (ADS)

    Snyder, G. T.; Dowling, C. B.; Harbert, A.; Lu, H.; Lyons, W. B.; Welch, K. A.

    2006-12-01

    Many of the McMurdo Dry Valleys lakes of Antarctica exhibit saline to hypersaline bottom waters whose chemistry is distinct from that of sea water. The source and relative abundance of dissolved Cl, Br, and I in these unusual waters has been modified by several potential processes including: seawater incursions, water- rock interactions, microbial scavenging, glacial melting and precipitation, and atmospheric deposition. Since all of these processes are affected by both long-term and short-term climate change, lake waters and the salts that are deposited around them provide sensitive indicators of lake dessication and refilling in the past. We present elemental analyses, not only of the lake water, but also of bottom sediments and cryogenic evaporites recovered from the Dry Valleys. XRD analyses indicate that gypsum and antarcticite are precipitated around saline lakes presently situated more than 40 km from the ocean (Vanda, Don Juan, Joyce), while mirabilite is found near small pools in the Garwood Valley, only a few km from the ocean. Lake water enrichments in Ca and Cl, relative to Na suggest that either dissolution of gypsum and antarcticite has occurred in Don Juan Pond and Lake Vanda, or that these two small bodies of water previously lost sodium to mirabilite formation. Lakes Fryxell and Joyce, as well as waters in Garwood Valley show near-sea water ratios. Dissolved iodine, and to a lesser extent bromine, are commonly associated with diagenesis of marine organic matter in regions of high productivity, so it is surprising that the Dry Valleys lake waters are enriched in these two elements. These enrichments are also apparent in pore fluids of shallow sediments on the lake bottoms. In addition, the sediments themselves are highly enriched in iodine in the upper 5 cm (up to 77 ppm). This is likely due to remobilization of dissolved iodide, which is mobile in reduced form, but becomes fixed as adsorbed or organic iodine upon diffusing into shallow oxic

  1. The record of historic earthquakes in lake sediments of Central Switzerland

    NASA Astrophysics Data System (ADS)

    Monecke, Katrin; Anselmetti, Flavio S.; Becker, Arnfried; Sturm, Michael; Giardini, Domenico

    2004-12-01

    Deformation structures in lake sediments in Central Switzerland can be attributed to strong historic earthquakes. The type and spatial distribution of the deformation structures reflect the historically documented macroseismic intensities thus providing a useful calibration tool for paleoseismic investigations in prehistoric lake sediments. The Swiss historical earthquake catalogue shows four moderate to strong earthquakes with moment magnitudes of Mw=5.7 to Mw=6.9 and epicentral intensities of I0=VII to I0=IX that affected the area of Central Switzerland during the last 1000 years. These are the 1964 Alpnach, 1774 Altdorf, 1601 Unterwalden, and 1356 Basel earthquakes. In order to understand the effect of these earthquakes on lacustrine sediments, four lakes in Central Switzerland (Sarner See, Lungerer See, Baldegger See, and Seelisberg Seeli) were investigated using high-resolution seismic data and sediment cores. The sediments consist of organic- and carbonate-rich clayey to sandy silts that display fine bedding on the centimeter to millimeter scale. The sediments are dated by historic climate and environmental records, 137Cs activity, and radiocarbon ages. Deformation structures occur within distinct zones and include large-scale slumps and rockfalls, as well as small-scale features like disturbed and contorted lamination and liquefaction structures. These deformations are attributed to three of the abovementioned earthquakes. The spatial distribution of deformation structures in the different lakes clearly reflects the historical macroseismic dataset: Lake sediments are only affected if they are situated within an area that underwent groundshaking not smaller than intensity VI to VII. We estimate earthquake size by relating the epicentral distance of the farthest liquefaction structure to earthquake magnitude. This relationship is in agreement with earthquake size estimations based on the historical dataset.

  2. Controls on the Composition and Distribution of Holocene Sediment in Lake Junín, Peru

    NASA Astrophysics Data System (ADS)

    Weidhaas, N.; Woods, A.; Abbott, M. B.; Rodbell, D. T.; Hatfield, R. G.; Larsen, D. J.; Brady, K.; Delgado, G.; Hillman, A. L.

    2015-12-01

    Lake Junín is a high-­elevation intermontane lake in the inner-­tropics of the South American Andes (11° S, 76.1° W) that is highly sensitive to changes in temperature and precipitation, and contains sediments that are well­-suited for multiproxy analysis and can be reliably dated. It is one of the few lakes in the tropical Andes that can provide a continuous record throughout the last glacial cycle and it is ideally situated to record long­-term variations in the South American Summer Monsoon. Lake Junín was drilled in 2015 to recover sediment cores which will provide the longest independently­-dated record of tropical water balance, glacier variability, vegetation history, and paleomagnetic secular variation for the region. We collected six cores across a NE­-SW transect to characterize the controls on sediment composition and distribution prior to drilling. The cores range from 2 to 9 m in length and each contains a complete Holocene section and glacial transition. Interglacial sediments are composed primarily of authigenic carbonates, whereas minerogenic material sourced from nearby glacial outwash fans dominates the late glacial sediment record. All cores exhibit a similar two-­component stratigraphy: an upper section of primarily whitish pink marl with intermittent light brown mud and a lower section of characteristic light gray glacial flour. Magnetic susceptibility data show that the carbonate/clastic contact deepens from NE to SW, and the thickness of the upper carbonate section displays a significant positive correlation with distance from the NE shore. Quantification of Holocene carbonate sediment dynamics in Lake Junín will facilitate more accurate interpretation of their stratigraphic significance in the longer sediment record.

  3. Occurrence and trends of selected nutrients, other chemical constituents, diatoms, and cyanobacteria in bottom sediment, Lake Maxinkuckee, northern Indiana

    USGS Publications Warehouse

    Juracek, Kyle E.

    2015-01-01

    Biological indicators in the bottom sediment provided evidence for an improving, or at least not worsening, lake trophic condition. The occurrence of multiple diatom species, none of which were overwhelmingly dominant, was indicative of a minimally contaminated lake ecosystem. The combined evidence of several diatom species in the recent sediment indicated that the lake had not become more productive in recent decades. The combined evidence provided by akinetes for three cyanobacterial genera in the recent and predevelopment sediment indicated similar nutrient conditions in the lake during the past 40 years and possibly back to at least the mid-1800s.

  4. Contamination and Risk Assessment of Heavy Metals in Lake Bed Sediment of a Large Lake Scenic Area in China

    PubMed Central

    Wan, Li; Xu, Liang; Fu, Yongsheng

    2016-01-01

    The exposure of heavy metals to lake bed sediment of scenic areas may pose risks on aquatic ecosystems and human health, however very few studies on risk assessment have been reported for scenic areas. Accordingly, this study determined concentration levels, and assessed contamination characteristics and risks, of heavy metals in lake bed sediment of National Scenic Areas Songhuahu (NSAS) in China. The concentrations of Zn, Cr, Pb, Ni, and Cu were determined in 29 bed sediment samples. Results showed that the mean values of Zn, Cr, Pb, Ni, and Cu were 92.69, 90.73, 38.29, 46.77, and 49.44 mg/kg, respectively. Pearson correlation coefficients indicated that organic matter was a major factor influencing distribution of heavy metals. The results for enrichment factors indicated that contamination rates and anthropogenic inputs of single heavy metals decreased in the order Cu > Ni > Pb > Cr > Zn; results of Nemerow integrated pollution index suggested that 72.41% of sampling sites were exposed to low to moderately integrated pollution, and 27.59% of sampling sites were exposed to strongly integrated pollution. According to results for potential ecological risk index, ecological risks of single and all the heavy metals in bed sediment from all the sampling sites were low. Human risks were assessed with hazardous quotients, and the results suggested that exposure of heavy metals to bed sediment posed no or little risk to human health, and the pathway of ingestion significantly contributed to human health risks. PMID:27455296

  5. Microbial community structure in methane hydrate-bearing sediments of freshwater Lake Baikal.

    PubMed

    Kadnikov, Vitaly V; Mardanov, Andrey V; Beletsky, Alexey V; Shubenkova, Olga V; Pogodaeva, Tatiana V; Zemskaya, Tamara I; Ravin, Nikolai V; Skryabin, Konstantin G

    2012-02-01

    Gas hydrates in marine sediments have been known for many years but recently hydrates were found in the sediments of Lake Baikal, the largest freshwater basin in the world. Marine gas hydrates are associated with complex microbial communities involved in methanogenesis, methane oxidation, sulfate reduction and other biotransformations. However, the contribution of microorganisms to the formation of gas hydrates remains poorly understood. We examined the microbial communities in the hydrate-bearing sediments and water column of Lake Baikal using pyrosequencing of 16S rRNA genes. Aerobic methanotrophic bacteria dominated the water sample collected at the lake floor in the hydrate-bearing site. The shallow sediments were dominated by Archaea. Methanogens of the orders Methanomicrobiales and Methanosarcinales were abundant, whereas representatives of archaeal lineages known to perform anaerobic oxidation of methane, as well as sulfate-reducing bacteria, were not found. Affiliation of archaea to methanogenic rather than methane-oxidizing lineages was supported by analysis of the sequences of the methyl coenzyme M reductase gene. The deeper sediments located at 85-90 cm depth close to the hydrate were dominated by Bacteria, mostly assigned to Chloroflexi, candidate division JS1 and Caldiserica. Overall, our results are consistent with the biological origin of methane hydrates in Lake Baikal.

  6. Remobilization and export of cadmium from lake sediments by emerging insects

    SciTech Connect

    Currie, R.S.; Fairchild, W.L.; Muir, D.C.G.

    1997-11-01

    Emerging insects including, Diptera, Odonata, Ephemeroptera, and Trichoptera were collected from Lake 382 (L382) in 1991 and 1992 to estimate quantitatively the export of Cd by aquatic insects from a natural system having elevated Cd concentrations in the water and sediment. L382 is a Canadian Shield lake, located within the Experimental Lakes Area in northwestern Ontario, that received experimental additions of Cd from 1987 to 1992. Emerging Diptera (mostly Chironomidae), Odonata, and Ephemeroptera had mean Cd concentrations of 1.41, 0.11, and 0.30 {micro}g/g wet weight, respectively. An estimated 1.32 to 3.90 g of Cd per year were exported from the sediments of L382 depending on the estimate of production rates used for these groups of insects. Approximately 0.05 to 0.17% of the whole-lake Cd load in L382 sediments was exported annually or 0.12 to 0.39% of the epilimnion Cd sediment load. Insect emergence may have resulted in greater Cd export from L382 relative to losses via the outflow. Cadmium exported from the sediments by insects may be remobilized and become more available to aquatic organisms or enter the terrestrial ecosystem and become available to insectivores.

  7. Temperature and Cyanobacterial Bloom Biomass Influence Phosphorous Cycling in Eutrophic Lake Sediments

    PubMed Central

    Chen, Mo; Ye, Tian-Ran; Krumholz, Lee R.; Jiang, He-Long

    2014-01-01

    Cyanobacterial blooms frequently occur in freshwater lakes, subsequently, substantial amounts of decaying cyanobacterial bloom biomass (CBB) settles onto the lake sediments where anaerobic mineralization reactions prevail. Coupled Fe/S cycling processes can influence the mobilization of phosphorus (P) in sediments, with high releases often resulting in eutrophication. To better understand eutrophication in Lake Taihu (PRC), we investigated the effects of CBB and temperature on phosphorus cycling in lake sediments. Results indicated that added CBB not only enhanced sedimentary iron reduction, but also resulted in a change from net sulfur oxidation to sulfate reduction, which jointly resulted in a spike of soluble Fe(II) and the formation of FeS/FeS2. Phosphate release was also enhanced with CBB amendment along with increases in reduced sulfur. Further release of phosphate was associated with increases in incubation temperature. In addition, CBB amendment resulted in a shift in P from the Fe-adsorbed P and the relatively unreactive Residual-P pools to the more reactive Al-adsorbed P, Ca-bound P and organic-P pools. Phosphorus cycling rates increased on addition of CBB and were higher at elevated temperatures, resulting in increased phosphorus release from sediments. These findings suggest that settling of CBB into sediments will likely increase the extent of eutrophication in aquatic environments and these processes will be magnified at higher temperatures. PMID:24682039

  8. Promise and Pitfalls of Using Grain Size Analysis to Identify Glacial Sediments in Alpine Lake Cores.

    NASA Astrophysics Data System (ADS)

    Clark, D. H.

    2011-12-01

    Lakes fed by glacier outwash should have a clastic particle-size record distinct from non-glacial lakes in the same area, but do they? The unique turquoise color of alpine glacial lakes reflects the flux of suspended clastic glacial rock flour to those lakes; conversely, lakes not fed by outwash are generally clear with sediments dominated by organics or slope-wash from nearby hillslopes. This contrast in sediment types and sources should produce a distinct and measureable different in grain sizes between the two settings. Results from a variety of lakes suggest the actual situation is often more subtle and complex. I compare grain size results to other proxies to assess the value of grain size analysis for paleoglacier studies. Over the past 10 years, my colleagues and I have collected and analyzed sediment cores from a wide variety of lakes below small alpine glaciers in an attempt to constrain the timing and magnitude of alpine glaciation in those basins. The basic concept is that these lakes act as continuous catchments for any rock flour produced upstream by glacier abrasion; as a glacier grows, the flux of rock flour to the lake will also increase. If the glacier disappears entirely, rock flour deposition will also cease in short order. We have focused our research in basins with simple sedimentologic settings: mostly small, high-altitude, stripped granitic or metamorphic cirques in which the cirque glaciers are the primary source of clastic sediments. In most cases, the lakes are fed by meltwater from a modern glacier, but were ice free during the earlier Holocene. In such cases, the lake cores should record formation of and changes in activity of the glacier upstream. We used a Malvern Mastersizer 2000 laser particle size analyzer for our grain size analyses, as well as recording magnetic susceptibility, color, and organics for the same cores. The results indicate that although lakes often experience increases in silt and clay-size (<0.63 mm) clastic

  9. The effect of lake browning and respiration mode on the burial and fate of carbon and mercury in the sediment of two boreal lakes

    NASA Astrophysics Data System (ADS)

    Isidorova, Anastasija; Bravo, Andrea G.; Riise, Gunnhild; Bouchet, Sylvain; Björn, Erik; Sobek, Sebastian

    2016-01-01

    In many northern temperate regions, the water color of lakes has increased over the past decades ("lake browning"), probably caused by an increased export of dissolved organic matter from soils. We investigated if the increase in water color in two lakes in Norway has resulted in increased burial of organic carbon (OC) and mercury (Hg) in the sediments and if the Hg was prone to methylation. Lake Solbergvann experienced a threefold water color increase, and OC burial increased approximately twofold concomitant to the water color increase. This lake had prolonged periods of anoxic bottom water, and anoxic OC mineralization rates were only about half of the oxic OC mineralization rates (7.7 and 17.5 g C m-2 yr-1, respectively), contributing to an efficient OC burial. In Lake Elvåga, where water color increase was only approximately twofold and bottom water was oxygenated, no recent increase in OC burial could be observed. Hg burial increased strongly in both lakes (threefold and 1.6-fold in Lake Solbergvann and Lake Elvåga, respectively), again concomitant to the recent water color increase. The proportion of methylated Hg (MeHg) in surficial sediment was 1 order of magnitude higher in Lake Elvåga (up to 6% MeHg) than in Lake Solbergvann (0.2-0.6% MeHg), probably related to the different oxygenation regimes. We conclude that lake browning can result in increased OC and Hg burial in lake sediments, but the extent of browning and the dominating mode of sediment respiration (aerobic or anaerobic) strongly affect burial and fate of OC and Hg in sediments.

  10. Vertical stability of mercury in historic and prehistoric sediments from Clear Lake, California.

    PubMed

    Suchanek, Thomas H; Richerson, Peter J; Zierenberg, Robert A; Slotton, Darell G; Mullen, Lauri H

    2008-12-01

    Clear Lake, California, USA, is the site of the Sulphur Bank Mercury Mine, now a U.S. Environmental Protection Agency Superfund Site. Intermittent mining from 1873 to 1957 resulted in approximately 100 Mg of mercury (Hg) being deposited into the lake's ecosystem. Sediment cores to approximately 2.5 m depth (dated using 210Pb and 14C) represent approximately 3000 years of sedimentation. Clear Lake sediments have experienced Hg deposition from anthropogenic sources (mining) during historic times (to the mid-1900s) and geologic sources during prehistoric times (prior to the mid-1800s). This provides a unique opportunity to evaluate hypotheses relating to (1) the influence of the mine on Hg loading to the lake and (2) the potential upward mobilization of Hg by diagenetic processes proposed by some as an alternative explanation for increased Hg concentrations at the surface of the sediment column believed to be caused by increased global atmospheric deposition. Although Hg mining began in 1873, no significant evidence of anthropogenic Hg loading was detected in cores prior to open-pit mining ca. 1927, which also involved bulldozing mine waste rock and tailings into the lake. Exponential increases in total Hg (TotHg) and methylmercury (MeHg) were observed above the 1927 horizon, where estimated sedimentation rates were 2.2-20.4 mm/yr and peaks of both forms of Hg maintained vertical stability within the sediment column. Below the 1927 horizon, a slow increase in both TotHg and MeHg with depth was observed from approximately 1000 to 3000 years before present, where sedimentation rates ranged from approximately 0.6 to 2.0 mm/yr and elevated Hg profiles appear stable. Vertical stability of Hg in the shallow and deep sediment column suggests that both TotHg and MeHg do not undergo diagenetic upward mobilization within the sediment column under rapid or slow sedimentation rates. Because (1) these data were collected at a site with known anthropogenic and geologic sources and

  11. Spatial and temporal trends in short-chain chlorinated paraffins in Lake Ontario sediments.

    PubMed

    Marvin, C H; Painter, S; Tomy, G T; Stern, G A; Braekevelt, E; Muir, D C G

    2003-10-15

    Short-chain chlorinated paraffins (polychlorinated-[C10-C13]-n-alkanes) were measured in Lake Ontario sediments collected during a lake-wide survey to characterize spatial and temporal trends in contamination. The Lake Ontario average SCCP sediment concentration was 49 ng/g (dry wt), which was somewhat higher than the lake-wide average for sigmaDDT (32 ng/g). Individual stations in each of the depositional basins exhibited the highest concentrations, ranging from 147 ng/g (dry wt) to 410 ng/g at an index station in the Niagara (western) basin. Relative average contributions of the carbon chain groups to total SCCPs on a lake-wide basis were as follows: sigmaC10 = 24%, sigmaC11 = 35%, sigmaC12 = 34%, sigmaC13 = 6.6%. Assessment of core profiles and estimates of SCCP fluxes indicated that an area of the western end of Lake Ontario is heavily impacted (SCCP flux of 170 microg/m2 yr) and potentially influenced by local industrial sources of SCCPs. Maximum accumulation of SCCPs in this area of the western basin occurred in the mid-1970s. In contrast, SCCP concentrations in a core from a site in the central area of the lake (SCCP flux of 8.0 microg/m2 yr) were more similar to levels characteristic of remote locations primarily impacted by atmospheric sources.

  12. Recent increase in mercury sedimentation in a forest lake attributable to peatland drainage

    SciTech Connect

    Simola, H.; Lodenius, M.

    1982-09-01

    In order to gain information about the natural background levels and about the recent history of mercury in Finnish waters, mercury profiles were determined in two lakes in which annually laminated sediment is deposited, and which differ from each other with respect to the history of land use in their drainage areas. Annual sediment laminations or varves allow a precise dating of the studied sequence, and their existence indicates undisturbed recording of the history of the environment.

  13. Quantifying Sediment Delivery History in Mediterranean Mountain Watersheds from Lake Records (Iberian Range, Spain)

    NASA Astrophysics Data System (ADS)

    Valero-Garcés, Blas; Barreiro-Lostres, Fernando; Moreno, Ana; González-Sampériz, Penélope; Giralt, Santiago; Nadal-Romero, Estela

    2016-04-01

    Land degradation and soil erosion are key environmental problems in Mediterranean mountains with long history of human occupation and strong seasonality of hydrological regimes. Monitoring studies in experimental catchments in the Pyrenees have identified main controlling factors on erosion dynamics but, because of the short time span, they do not integrate the diverse temporal and spatial variability of these environments. We propose a novel strategy based on multi-proxy analyses of lake sediments aimed to quantify sediment delivery and erosion dynamics. Karstic lakes in the Iberian Range (Spain) provide the opportunity to reconstruct the depositional evolution of Mediterranean mountain watersheds and to evaluate the response to both, anthropogenic and climate forcings during the last millennia. Precipitation (rainfall intensity, seasonality, runoff production) and land cover (forest area, degraded areas, land uses) are key factors controlling erosion in both experimental and lake catchments. Values for Minimum Denuded Mass (Mdc) and Total Denudation Rate (DRt) measured in experimental catchments and reconstructed from lake sequences are comparable. In both settings, most sediment yield occurs during flooding events. The reconstructed sediment delivery to the lakes during flood events spans several orders or magnitude (less than 100 T to 98000 T) and the denudation rate ranges from 6 to 480 T km-2 yr-1. Reconstructed mass denudation values per event in the forested lake catchments are similar (less than 30 T km-2 yr-1) to sediment yields from a high altitude experimental watershed. Flood sediment yield values from an abandoned farmland experimental catchment (69 T km2) are in the lower range of lake watersheds (from 60 to 480 T km-2 yr-1). No lake watershed has reached the values documented for the badland catchment (3094 T km-2). These results underline the punctuated nature of sediment dynamics in Mediterranean landscapes at decadal and centennial scales. Major

  14. 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.

  15. Bioaccumulation of atrazine and chlorpyrifos to Lumbriculus variegatus from lake sediments.

    PubMed

    Jantunen, A P K; Tuikka, A; Akkanen, J; Kukkonen, J V K

    2008-11-01

    The bioaccumulation of the pesticides chlorpyrifos and atrazine to the benthic oligochaeta Lumbriculus variegatus from four diverse artificially contaminated lake sediments (OC 0.13-21.5%) was studied in the laboratory. The steady state of bioaccumulation was not reached within 10d. Chlorpyrifos showed stronger bioaccumulation than the less lipophilic atrazine, the biota-sediment accumulation factors (BSAFs) being 6.2-99 for the former and 1.9-5.3 for the latter. While bioaccumulation factors (BAFs) dropped with increasing organic content of the sediments, the high level and considerable range of the obtained BSAFs indicate other sediment qualities, such as the age and characteristics of the organic material, having a strong effect on the bioavailability of these compounds. The slow and incomplete desorption of chlorpyrifos from the most inorganic sediment indicates also that this compound may be strongly bound to some type of inorganic material. Any specific influential sediment fraction or characteristic could not be identified.

  16. Geochemical and Geophysical Analysis of Holocene-aged Sediments from Southeastern Tulare Lake, CA

    NASA Astrophysics Data System (ADS)

    Prosser, L.; Jackson, B.; Roza, J.

    2015-12-01

    Tulare Lake is located in the San Joaquin Valley of California west of the Sierra Nevada mountains (Preston, 1981). The Poso Canal trench locality is located in the southeastern portion of Tulare Lake in the Ton Tachi lake plane south of the Atwell Island sand spit. This area was chosen because these sediments lie beneath a road bed that predates agricultural tilling, preserving late-Holocene lake sediments. Sediments from trench TL13-7C were sampled for geophysical and geochemical analyses in order to create a higher resolution lake-level history during the late-Holocene than had been possible using only lithologic descriptions. The new record is comprised of grain size, clay percentage, carbon/nitrogen (C/N) ratios, total inorganic carbon (TIC), total organic carbon (TOC), and nitrogen (N) analyses taken at 2-cm intervals over 181-cm of section comprising four lithologic units. From oldest to youngest, Unit 1A consists of relatively equal and steady percentages of clay, silt, and sand, and relatively low C/N ratios, TIC, TOC, and N, suggesting an unproductive lake and relatively deep lake levels at this high elevation site. Fluctuating C/N ratios, a steady decrease in clay percentage, and a steady increase in sand percentage in Unit 1B suggests periods of flooding and fluctuating lake levels and eventually shallow evaporative lake conditions, as evidenced by a considerable and sudden increase in TIC (to 4.51%) in Unit 2. In addition to the drastic change in TIC, Unit 2 shows evidence of a large influx of terrestrial organic matter perhaps transported by floods by an increase in sand percentage and two pronounced spikes in C/N ratios to 38 and 65 (Meyers and Lallier-Verges, 1999). Unit 3 shows low but steady levels of clay and sand percentages, and higher but steady levels of silt. Levels of TIC, TOC, C/N, and N are all steady, with relatively higher levels of TOC and N, which are indicators of high lake level and productivity (Cohen, 2003). Unit 4 is very similar

  17. The Influence of Macrophytes on Sediment Resuspension and the Effect of Associated Nutrients in a Shallow and Large Lake (Lake Taihu, China)

    PubMed Central

    Zhu, Mengyuan; Zhu, Guangwei; Nurminen, Leena; Wu, Tingfeng; Deng, Jianming; Zhang, Yunlin; Qin, Boqiang; Ventelä, Anne-Mari

    2015-01-01

    A yearlong campaign to examine sediment resuspension was conducted in large, shallow and eutrophic Lake Taihu, China, to investigate the influence of vegetation on sediment resuspension and its nutrient effects. The study was conducted at 6 sites located in both phytoplankton-dominated zone and macrophyte-dominated zone of the lake, lasting for a total of 13 months, with collections made at two-week intervals. Sediment resuspension in Taihu, with a two-week high average rate of 1771 g·m-2·d-1 and a yearly average rate of 377 g·m-2·d-1, is much stronger than in many other lakes worldwide, as Taihu is quite shallow and contains a long fetch. The occurrence of macrophytes, however, provided quite strong abatement of sediment resuspension, which may reduce the sediment resuspension rate up to 29-fold. The contribution of nitrogen and phosphorus to the water column from sediment resuspension was estimated as 0.34 mg·L-1 and 0.051 mg·L-1 in the phytoplankton-dominated zone. Sediment resuspension also largely reduced transparency and then stimulated phytoplankton growth. Therefore, sediment resuspension may be one of the most important factors delaying the recovery of eutrophic Lake Taihu, and the influence of sediment resuspension on water quality must also be taken into account by the lake managers when they determine the restoration target. PMID:26030094

  18. Assessing Suspended-Sediment Transport Rates at the Regional Scale: Lake Tahoe Basin

    NASA Astrophysics Data System (ADS)

    Heins, A.; Simon, A.

    2003-12-01

    In recent years, suspended-sediment transport has received increased attention due to a greater emphasis being placed on water quality issues. Secchi-disk data has shown a trend of decreasing water clarity in Lake Tahoe over the past 35 years that can be partly attributed to delivery of fine sediment from channel and upland sources. In an effort to quantify the magnitude and sources of suspended sediment into Lake Tahoe, the USDA-ARS National Sedimentation Laboratory with support from the U.S. Army Corps of Engineers initiated a study to examine these issues. Historical flow and sediment-transport data from more than 30 gages were used to determine bulk suspended-sediment loads and yields for sites around the lake. Eighteen index stations were used to make comparisons between sediment production and delivery from individual watersheds and between different sides of the lake. Fine-grained sediment transport was determined for 20 sites based on relations derived from particle-size distributions across the range of measured flows. Suspended-sediment loads and yields vary over orders of magnitude from year to year, from west to east and north to south across the basin. Median annual suspended-sediment loads for index stations range from about 2200 tonnes/yr (T/y) from the Upper Truckee River to 3 T/y from Logan House Creek. Based on the historical data, the largest annual contributors of sediment are in decreasing order, Upper Truckee River (2200 T/y), Blackwood Creek (1930 T/y), Second Creek (1410 T/y), Trout Creek (1190 T/y), Third Creek (880 T/y) and Ward Creek (855 T/y). Data from Second and Third Creeks may be somewhat misleading though because of a short period of data collection in the case of the former, and the fact that data collection occurred during major construction activities and following storm-induced debris flows in these basins. Analysis of suspended-sediment transport ratings with longer periods of record show that sediment loads from northeastern

  19. Authigenic phyllosilicates in modern acid saline lake sediments and implications for Mars

    NASA Astrophysics Data System (ADS)

    Story, Stacy; Bowen, Brenda Beitler; Benison, Kathleen Counter; Schulze, Darrell G.

    2010-12-01

    Aluminum- and Fe/Mg-phyllosilicates are considered important geochemical indicators in terrestrial and Martian sedimentary systems. Traditionally, Al-phyllosilicates are characterized as forming and remaining stable under conditions of low to moderate pH, while Fe/Mg-phyllosilicates are considered representative of only dilute and moderate to high pH conditions. However, we have observed Al- and Fe/Mg-phyllosilicates in acid saline lake sediments in Western Australia. Phyllosilicate formation mechanisms in these lake systems include direct precipitation from lake waters, early diagenetic precipitation from shallow groundwaters, and deposition/alteration of detrital grains. X-ray diffraction analysis of silt- and clay-size sediments from two acid saline lakes in Western Australia indicates the presence of several complex mineral assemblages with extreme spatial heterogeneity that reflects the complex geochemistry of these lakes. These assemblages include unique combinations of authigenic and/or detrital phyllosilicates (e.g., kaolinite, smectite, and palygorskite-sepiolite), sulfates (e.g., alunite, jarosite, and gypsum), Fe-oxides (e.g., hematite and goethite), and other silicates (e.g., mullite and heulandite-clinoptilolite). Observations of Fe/Mg-phyllosilicates found in acid saline sediments in southern Western Australia suggest their degradation under conditions of low pH (2.5-5.4) is slowed by the high salinity (5-25%) of the lake and shallow groundwaters. The occurrence of both Al- and Fe/Mg-phyllosilicates in these acid saline lake sediments suggests that environmental interpretations based on the occurrence of phyllosilicates require additional consideration of their spatial distribution and association with other minerals. Moreover, the similarity between the diverse mineral assemblages in these terrestrial acid saline systems and those on Mars indicates similar conditions may have existed on Mars.

  20. Speciation and isotopic composition of sulfur in sediments from Jellyfish Lake, Palau

    USGS Publications Warehouse

    Bates, A.L.; Spiker, E. C.; Orem, W.H.; Burnett, W.C.

    1993-01-01

    Jellyfish Lake, Palau, is a meromictic marine lake with high organic productivity, low reactive Fe content, and anoxic bottom waters. Sediment samples from Jellyfish Lake were examined for the distribution of sulfur species and their isotopic signatures in order to gain a better understanding of sedimentary sulfur incorporation in Fe-poor environments. Surface samples were taken along a transect from a near-shore site to the center of the lake, and include a sample below oxic water, a sample below the chemocline layer, and samples below anoxic waters. Three additional samples were taken from a core, 2 m long, collected near the lake center. Sulfur to organic carbon weight ratios in all samples were lower than the expected value of 0.36 for normal marine sediment, probably because the lake water is deficient in reactive Fe to form iron sulfides. Total sulfur contents in the surface sediments indicated no changes with distance from shore; however, the sulfur content of the surface sample at the chemocline layer may be slightly higher. Total sulfur content increased with depth in the core and is inversely related to organic carbon content. Organic sulfur is the major sulfur species in the samples, followed in descending order by sulfate, disulfides and monosulfides. Sulfate sulfur isotope ??34S-values are positive (from +20.56 to +12.04???), reflecting the marine source of sulfate in Jellyfish Lake. Disulfide and monosulfide ??34S-values are negative (from -25.07 to -7.60???), because of fractionation during bacterial reduction of sulfate. Monosulfide ??34S-values are somewhat higher than those of disulfides, and they are close to the ??34S-values of organic sulfur. These results indicate that most of the organic sulfur is formed by reaction of bacteriogenic monosulfides, or possibly monosulfide-derived polysulfides, with organic matter in the sediment. ?? 1993.

  1. Agricultural pesticides in Mississippi Delta oxbow lake sediments during autumn and their effects on Hyalella azteca.

    PubMed

    Lizotte, Richard E; Knight, Scott S; Bryant, Charles T; Smith, Sammie

    2009-10-01

    Agricultural pesticide contamination of sediments from five Mississippi Delta oxbow lakes and their effects and bioavailablity to Hyalella azteca were assessed during a low-application season-autumn. Three reference oxbow lakes were located in the White River National Wildlife Refuge (WRNWR), Arkansas and two impaired lakes, according to the US Environmental Agency Sect. 303 (d) Clean Water Act, were located in Mississippi. Surface sediment (top 5 cm) was collected at three sites within each lake and analyzed for 17 current and historic-use pesticides and metabolites. Chronic 28-day H. azteca sediment bioassays and pesticide body residue analyses were completed to determine the degree of biological responses and bioavailability. The greatest number of detectable pesticides in WRNWR and 303 (d) sediment samples was 9 and 12, respectively, with historic-use pesticide metabolite, p,p'-DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene] ubiquitous. No significant (p > 0.05) differences in animal survival were observed among sites. Animal growth was significantly (p < 0.05) less at only one site in a 303 (d)-listed lake (Macon Lake). Only six pesticides were observed in H. azteca with current-use pesticides detected at three sites; historic-use pesticides and metabolites detected at 11 sites. Animal body residues of a historic-use pesticide (dieldrin) and metabolite (p,p'-DDE) were associated with observed growth responses. Results show limited current-use pesticide contamination of sediments and H. azteca body tissues during autumn and that historic-use pesticides and metabolites are the primary contributors to observed biological responses.

  2. Identification of functionally active aerobic methanotrophs in sediments from an arctic lake using stable isotope probing

    USGS Publications Warehouse

    He, Ruo; Wooller, Matthew J.; Pohlman, John W.; Catranis, Catharine; Quensen, John; Tiedje, James M.; Leigh, Mary Beth

    2012-01-01

    Arctic lakes are a significant source of the greenhouse gas methane (CH4), but the role that methane oxidizing bacteria (methanotrophs) play in limiting the overall CH4 flux is poorly understood. Here, we used stable isotope probing (SIP) techniques to identify the metabolically active aerobic methanotrophs in upper sediments (0–1 cm) from an arctic lake in northern Alaska sampled during ice-free summer conditions. The highest CH4 oxidation potential was observed in the upper sediment (0–1 cm depth) with 1.59 μmol g wet weight-1 day-1 compared with the deeper sediment samples (1–3 cm, 3–5 cm and 5–10 cm), which exhibited CH4 oxidation potentials below 0.4 μmol g wet weight-1 day-1. Both type I and type II methanotrophs were directly detected in the upper sediment total communities using targeted primer sets based on 16S rRNA genes. Sequencing of 16S rRNA genes and functional genes (pmoA and mxaF) in the 13C-DNA from the upper sediment indicated that type I methanotrophs, mainly Methylobacter, Methylosoma, Methylomonas and Methylovulum miyakonense, dominated the assimilation of CH4. Methylotrophs, including the genera Methylophilus and/or Methylotenera, were also abundant in the 13CDNA. Our results show that a diverse microbial consortium acquired carbon from CH4 in the sediments of this arctic lake.

  3. Sediments as tracers for transport and deposition processes in peri-alpine lakes: A case study

    NASA Astrophysics Data System (ADS)

    Righetti, Maurizio; Toffolon, Marco; Lucarelli, Corrado; Serafini, Michele

    2011-12-01

    SummaryThe benthic sediment fingerprint is analysed in the small peri-alpine lake Levico (Trentino, Italy) to identify the causes of recurrent phenomena of turbidity peaks, particularly evident in a littoral region of the water body. In order to study the sediment transport processes, we exploit the fact that the sediment supply from the major tributary has a specific chemical composition, which differs from that of the nearby lake basin. Three elements (Fe, Al, K) have been used as tracers to identify the source and the deposition patterns of tributary sediments, and another typical element, Si, has been critically analysed because of its dual (allochthonous and autochthonous) origin. Several samples of the benthic material have been analysed using SEM-EDS, and the results of the sedimentological characterisation have been compared with the patterns of sediment accumulation at the bed of the lake obtained using a three-dimensional numerical model, in response to the tributary supply under different external forcing and stratification conditions. The coupled use of field measurements and numerical results suggests that the turbidity phenomena are strongly related to the deposition of the sediments supplied by the tributary stream, and shows that it is possible to reconstruct the process of local transport when the tributary inflow is chemically specific.

  4. Production of Hexagenia limbata nymphs in contaminated sediments in the Upper Great Lakes connecting channels

    USGS Publications Warehouse

    Edsall, Thomas A.; Manny, Bruce A.; Schloesser, Donald W.; Nichols, Susan J.; Frank, Anthony M.

    1991-01-01

    In April through October 1986, we sampled sediments and populations of nymphs of the burrowing mayfly, Hexagenia limbata (Serville), at 11 locations throughout the connecting channels of the upper Great Lakes, to determine if sediment contaminants adversely affected nymph production. Production over this period was high (980 to 9231 mg dry wt m-2) at the five locations where measured sediment levels of oil, cyanide, and six metals were below the threshold criteria of the U.S. Environmental Protection Agency and the Ontario Ministry of Environment for contaminated or polluted sediments, and also where the criterion for visible oil given in the Water Quality Agreement between the U.S.A. and Canada for connecting waters of the Great Lakes was not exceeded. At the other six locations where sediments were polluted, production was markedly lower (359 to 872 mg dry wt m-2). This finding is significant because it indicates that existing sediment quality criteria can be applied to protect H. limbata from oil, cyanide, and metals in the Great Lakes and connecting channels where the species fulfills a major role in secondary production and trophic transfer of energy.

  5. Results of submerged sediment core sampling and analysis on Par Pond, Pond C, and L Lake: July 1995

    SciTech Connect

    Koch, J.W. II; Martin, F.D.; Friday, G.P.

    1996-06-01

    Sediment cores from shallow and deep water locations in Par Pond, Pond C, and L Lake were collected and analyzed in 1995 for radioactive and nonradioactive constituents. This core analysis was conducted to develop a defensible characterization of contaminants found in the sediments of Par Pond, Pond C, and L Lake. Mercury was the only nonradiological constituent with a nonestimated quantity that was detected above the U.S Environmental Protection Agency Region IV potential contaminants of concern screening criteria. It was detected at a depth of 0.3--0.6 meters (1.0--2.0 feet) at one location in L Lake. Cesium-137, promethium-146, plutonium-238, and zirconium-95 had significantly higher concentrations in Par Pond sediments than in sediments from the reference sites. Cobalt-60, cesium-137, plutonium-238, plutonium-239/240, and strontium-90 had significantly higher concentrations in L-Lake sediments than sediments from the reference sites.

  6. Effects of hurricanes Katrina and Rita on the chemistry of bottom sediments in Lake Pontchartrain, Louisiana, USA

    USGS Publications Warehouse

    Van Metre, P.C.; Horowitz, A.J.; Mahler, B.J.; Foreman, W.T.; Fuller, C.C.; Burkhardt, M.R.; Elrick, K.A.; Furlong, E.T.; Skrobialowski, S.C.; Smith, J.J.; Wilson, J.T.; Zaugg, S.D.

    2006-01-01

    The effects of Hurricanes Katrina and Rita and the subsequent unwatering of New Orleans, Louisiana, on the sediment chemistry of Lake Pontchartrain were evaluated by chemical analysis of samples of street mud and suspended and bottom sediments. The highest concentrations of urban-related elements and compounds (e.g., Pb, Zn, polycyclic aromatic hydrocarbons, and chlordane) in bottom sediments exceeded median concentrations in U.S. urban lakes and sediment-quality guidelines. The extent of the elevated concentrations was limited, however, to within a few hundred meters of the mouth of the 17th Street Canal, similar to results of historical assessments. Chemical and radionuclide analysis of pre- and post-Hurricane Rita samples indicates that remobilization of near-shore sediment by lake currents and storms is an ongoing process. The effects of Hurricanes Katrina and Rita on the sediment chemistry of Lake Pontchartrain are limited spatially and are most likely transitory. ?? 2006 American Chemical Society.

  7. Sequential extraction analyses of Hg speciation in northern lake sediments undergoing primary production increases due to recent warming.

    NASA Astrophysics Data System (ADS)

    Outridge, Peter

    2013-04-01

    The "algal scavenging" hypothesis has been proposed to account for the discrepancy between increasing Hg fluxes in northern Canadian lake sediments while atmospheric Hg concentrations over recent decades have been declining. We propose that increased algal scavenging, due to higher phytoplankton growth caused by a change in lake ice regimes, can increase the sedimentation rate of available Hg from the water column. One consequence would be that sediment Hg fluxes are disconnected from the rate of atmospheric Hg deposition in northern regions. A prediction which flows from this hypothesis is that higher Hg concentrations would be found in the organic-bound fraction in sediments deposited during recent and medieval warm periods, compared to sediments deposited during cooler periods. Here, we present sequential fractionation data on sediment Hg, from recent decades in three Arctic lakes and from the Medieval Warm Period in one of these lakes. The veracity of the hypothesis will be evaluated in the light of these data.

  8. A qualitative assessment of the influence of bioturbation in Lake Baikal sediments

    NASA Astrophysics Data System (ADS)

    Martin, Patrick; Boes, Xavier; Goddeeris, Boudewijn; Fagel, Nathalie

    2005-04-01

    The impact of bioturbation in Lake Baikal sediments, particularly on rhythmic layering and mixing, was assessed by studying the actual vertical distribution of benthic animals in continuous accumulation zones selected by seismic survey (Vydrino Shoulder, Posolskoe Bank, Continent Ridge). To assess the influence of the bioturbation, animals were extracted from short cores and identified at the relevant taxonomic level. The faunal distribution is examined in parallel with the bioturbation tracks observed in thin section. Oligochaeta, Nematoda, Ostracoda, Copepoda, Gammaridae, Chironomidae and Hydrachnidia were found inhabiting the sediment. Among them, only oligochaete worms were assumed to have a significant impact on sediment mixing because of their "conveyor belt" feeding. The other two most abundantly sampled groups, nematods and copepods, belong to the interstitial fauna that has no significant impact on the vertical displacement of sediment particles and do not ingest the sediment. The presence of a benthic fauna as deep as 15 cm in the sediment indicates that the possibility of sediment disturbance by invertebrate activity cannot be dismissed in Lake Baikal. The effect of biological mixing is more limited in the deepest stations because the number of potential bioturbators is reduced, qualitatively as well as quantitatively. Located in the abyssal zone, Continent and Vydrino (but outside turbidites) deep stations appear to be most promising sediment records for tracking climate signal at high resolution.

  9. Impact of Placer Mining on Sediment Transport in Headwaters of the Lake Baikal Basin.

    NASA Astrophysics Data System (ADS)

    Pietron, J.; Jarsjo, J.; Chalov, S.

    2015-12-01

    Adverse practices in alluvial surface mining (placer mining) can lead to shifts in sediment transport regimes of rivers. However, some placer mines are located in remote parts of river basins, which constrain data availability in mining impact assessments. One such mining area is the Zaamar Goldfield (Northern Mongolia) which stretches 60 km along the Tuul River. The area is located in the headwaters of the Lake Baikal Basin, and may impact the UNESCO World Heritage Site of Lake Baikal. Previous studies indicate that the mining industry in the Zaamar Goldfield loads the river system with considerable amount of contaminated sediments (heavy metals). Still, transport processes and possible changes in local to regional sediment transport need to be better understood. In this work, we use snapshot field measurements and various flow and transport modelling techniques to analyze (1) the impact of placer mining in the sediment delivery to the river system and (2) the dynamics of further sediment transport to downstream Tuul River. Our results indicate that surface mining operations and waste management have considerable impact on the sediment input from the landscape. Furthermore, dynamic in-channel storage of sediments can act as intermittent sources of mining sediments. These effects occur in addition to impacts of on-going changes in hydro-climatic conditions of the area. We hope that our methodology and results will aid in studying similar unmonitored and mining-affected river basins.

  10. Discriminating between subglacial and proglacial lake sediments: an example from the Dänischer Wohld Peninsula, northern Germany

    NASA Astrophysics Data System (ADS)

    Livingstone, Stephen J.; Piotrowski, Jan A.; Bateman, Mark D.; Ely, Jeremy C.; Clark, Chris D.

    2015-03-01

    Subglacial lakes are common features of contemporary ice masses. However, they are rarely identified in the geological record. This is due to the difficulty in discriminating between subglacial and proglacial lake sediments; a proglacial origin is typically preferred as the ';simplest' explanation. We hypothesise that numerous deposits currently interpreted to record proglacial lake sedimentation may actually have a subglacial origin. Here we try and find ways of distinguishing proglacial from subglacial lake sediments by investigating three sites along the Dänischer Wohld Peninsula, northern Germany, which have been interpreted to record both proglacial and subglacial sedimentation. We identify two major phases of ice activity and associated lake formation during the Late Weichselian glaciation. (1) Proglacial lake formation at ˜23 ka in front of the advancing Baltic Ice Stream. This lake was subsequently overridden and the sediments glaciotectonised as ice continued to advance to its maximum extent. (2) Retreat of ice back into the Baltic Basin at ˜19 ka and formation of a proglacial lake that persisted for ˜4 ka. We suggest that subglacial lake activity may have occurred at two of the sites between 23 and 19 ka. This is based on the presence of aggrading sediment deposits characterised by stratified/laminated diamictons and interbedded tabular to channelized sorted sediments, the juxtaposition of relatively undeformed waterlain sediment and subglacial till, absence of glaciotectonic thrusting and folding or of fining/coarsening successions and the geomorphic association with tunnel valleys to the south of the study area. The style of sedimentation and deformation provided the greatest insight into the discrimination of proglacially vs subglacially deposited glaciolacustrine sediments. The luminescence signal palaeodose distributions also offers a potentially powerful means of fingerprinting sediment transport pathways of young glacial systems.

  11. A comparison of sediment toxicity test methods at three Great Lake Areas of Concern

    USGS Publications Warehouse

    Burton, G. Allen; Ingersoll, Christopher G.; Burnett, LouAnn C.; Henry, Mary; Hinman, Mark L.; Klaine, Stephen J.; Landrum, Peter F.; Ross, Phillipe; Tuchman, Marc

    1996-01-01

    The significance of sediment contamination is often evaluated using sediment toxicity (bioassay) testing. There are relatively few “standardized” test methods for evaluating sediments. Popular sediment toxicity methods examine the extractable water (elutriate), interstitial water, or whole (bulk) sediment phases using test species spanning the aquatic food chain from bacteria to fish. The current study was designed to evaluate which toxicity tests were most useful in evaluations of sediment contamination at three Great Lake Areas of Concern. Responses of 24 different organisms including fish, mayflies, amphipods, midges, cladocerans, rotifers, macrophytes, algae, and bacteria were compared using whole sediment or elutriate toxicity assays. Sediments from several sites in the Buffalo River, Calumet River (Indiana Harbor), and Saginaw River were tested, as part of the U.S. Environmental Protection Agency's (USEPA) Assessment and Remediation of Contaminated Sediments (ARCS) Project. Results indicated several assays to be sensitive to sediment toxicity and able to discriminate between differing levels of toxicity. Many of the assay responses were significantly correlated to other toxicity responses and were similar based on factor analysis. For most applications, a test design consisting of two to three assays should adequately detect sediment toxicity, consisting of various groupings of the following species: Hyalella azteca, Ceriodaphnia dubia, Chironomus riparius, Chironomus tentans, Daphnia magna, Pimephales promelas, Hexagenia bilineata, Diporeia sp., Hydrilla verticillata, or Lemna minor.

  12. Determination of specific molecular markers of biomass burning in lake sediments

    NASA Astrophysics Data System (ADS)

    Kirchgeorg, Torben; Schüpbach, Simon; Kehrwald, Natalie; McWethy, David; Barbante, Carlo

    2014-05-01

    Fire influences regional to global atmospheric chemistry and climate. Molecular markers of biomass burning archived in lake sediments are becoming increasingly important in paleoenvironmental reconstruction and may help determine interactions between climate and fire activity. One group of these molecular markers is the monosaccharide anhydrides levoglucosan, mannosan and galactosan. Several aerosol studies and recent ice core research use these compounds as a marker for biomass burning, but studies from lake sediment cores are rare. Previous sediment methods used gas chromatography - mass spectrometry and required derivatization of samples. Here, we present a high performance anion exchange chromatography-mass spectrometry method to allow separation and detection of the three monosaccharide anhydrides in lake sediments with implications for reconstructing past biomass burning events. We validated the method by quantifying levoglucosan, mannosan and galactosan in selected sediment core samples from Lake Kirkpatrick, New Zealand. The freeze-dried, milled and homogenized sediment samples were first extracted with methanol by pressurized solvent extraction, pre-concentrated and finally separated and analyzed by high performance anion exchange chromatography-mass spectrometry. We compared these isomers with macroscopic charcoal concentrations, as charcoal is a well-known proxy for biomass burning. In addition, we applied the method to a sediment core from Lake Petén Itzá, Guatemala to prove the suitability of these markers for reconstructing biomass burning history over the entire Holocene. In the Lake Kirkpatrick samples, levoglucosan, mannosan and galactosan concentrations significantly correlate with macroscopic charcoal concentrations. The three isomers are present in samples without any macroscopic charcoal, and may reflect the presence of microscopic charcoal. Levoglucosan/mannosan and levoglucosan/(mannosan+galactosan) ratios differ between samples with high

  13. Role of storms and forest practices in sedimentation of an Oregon Coast Range lake

    NASA Astrophysics Data System (ADS)

    Richardson, K.; Hatten, J. A.; Wheatcroft, R. A.; Guerrero, F. J.

    2014-12-01

    The design of better management practices in forested watersheds to face climate change and the associated increase in the frequency of extreme events requires a better understanding of watershed responses to extreme events in the past and also under management regimes. One of the most sensitive watershed processes affected is sediment yield. Lake sediments record events which occur in a watershed and provide an opportunity to examine the interaction of storms and forest management practices in the layers of the stratigraphy. We hypothesize that timber harvesting and road building since the 1900s has resulted in increases in sedimentation; however, the passage of the Oregon Forest Practices Act (OFPA) in 1972 has led to a decrease in sedimentation. Sediment cores were taken at Loon Lake in the Oregon Coast Range. The 32-m deep lake captures sediment from a catchment highly impacted by recent land use and episodic Pacific storms. We can use sedimentological tools to measure changes in sediment production as motivated by extreme floods before settlement, during a major timber harvesting period, and after installation of forestry Best Management Practices. Quantification of changes in particle size and elemental composition (C, N, C/N) throughout the cores can elucidate changes in watershed response to extreme events, as can changes in layer thickness. Age control in the cores is being established by Cesium-137 and radiocarbon dating. Given the instrumental meteorological data and decadal climate reconstructions, we will disentangle climate driven signals from changes in land use practices. The sediment shows distinct laminations and varying thickness of layers throughout the cores. Background deposition is composed of thin layers (<0.5 cm) of fine silts and clays, punctuated by thicker layers (3-25 cm) every 10 to 75 cm. These thick layers consist of distinctly textured units, generally fining upward. We interpret the thick layers in Loon Lake to be deposited by

  14. Linking Sediment Microbial Communities to Carbon Cycling in High-Latitude Lakes

    NASA Astrophysics Data System (ADS)

    Emerson, J. B.; Varner, R. K.; Johnson, J. E.; Owusu-Dommey, A.; Binder, M.; Woodcroft, B. J.; Wik, M.; Freitas, N. L.; Boyd, J. A.; Crill, P. M.; Saleska, S. R.; Tyson, G. W.; Rich, V. I.

    2015-12-01

    It is well recognized that thawing permafrost peatlands are likely to provide a positive feedback to climate change via CH4 and CO2 emissions. High-latitude lakes in these landscapes have also been identified as sources of CH4 and CO2 loss to the atmosphere. To investigate microbial contributions to carbon loss from high-latitude lakes, we characterized sediment geochemistry and microbiota via cores collected from deep and shallow regions of two lakes (Inre Harrsjön and Mellersta Harrsjön) in Arctic Sweden in July, 2012. These lakes are within the Stordalen Mire long-term ecological area, a focal site for investigating the impacts of climate change-related permafrost thaw, and the lakes in this area are responsible for ~55% of the CH4 loss from this hydrologically interconnected system. Across 40 samples from 4 to 40 cm deep within four sediment cores, Illumina 16S rRNA gene sequencing revealed that the sedimentary microbiota was dominated by candidate phyla OP9 and OP8 (Atribacteria and Aminicenantes, respectively, including putative fermenters and anaerobic respirers), predicted methanotrophic Gammaproteobacteria, and predicted methanogenic archaea from the Thermoplasmata Group E2 clade. We observed some overlap in community structure with nearby peatlands, which tend to be dominated by methanogens and Acidobacteria. Sediment microbial communities differed significantly between lakes, by overlying lake depth (shallow vs. deep), and by depth within a core, with each trend corresponding to parallel differences in biogeochemical measurements. Overall, our results support the potential for significant microbial controls on carbon cycling in high-latitude lakes associated with thawing permafrost, and ongoing metagenomic analyses of focal samples will yield further insight into the functional potential of these microbial communities and their dominant members.

  15. Laboratory experiment to determine phosphate release rates from sediments of a formerly oligotrophic lake (Silbersee, Cuxhaven)

    NASA Astrophysics Data System (ADS)

    Elmarami, Hatem; Greskowiak, Janek; Hamann, Enrico; Massmann, Gudrun

    2016-04-01

    The Silbersee is a small, formerly oligotrophic lake in northwestern Germany which still contains rare character species for oligotrophic lakes (Isoëtes lacustris, Littorella uniflora) threatened by eutrophication. It was suspected that the lake sediments and the redox conditions in the hypolimnon play an important role with regard to eutrophication, potentially releasing phosphorus (P) into the water column. This was the motivation to conduct experiments to estimate the release rate of phosphorus into the lake. It had been noted that the P concentrations in the bottom water were higher during summer in the stagnation phase, when conditions turned sulfidic. Eight sediment cores were taken with a Mondsee-corer (manufactured by UWITEC) at different sites of the lake. The thickness of the sediment within the cores ranged from 15cm to 35 cm and were overlying by approximately 40cm of lake water water. The headspace was approximately 10cm. The cores were stored in a fridge first under oxic, then under anoxic conditions as observed in the lake bottom water in the different seasons. Redox conditions were maintained by bubbling with oxygen and nitrogen gas during the respective time periods. During the experiment, the temperature was held constant to match the water temperature measured at the bottom of the lake (~ 7±1°C). Concentrations of total phosphorus (TP) and dissolved phosphorus (DP), iron (Fe) and dissolved oxygen (DO) as well as pH were measured under oxic and anoxic conditions in the water column. The results showed that TP, DP and Fe concentrations were higher under anoxic conditions than under oxic conditions. The observed increase of phosporous in the water column during the anoxic phase was presumably a result of (i) reductive Fe-oxides dissolution and the corresponding loss of sorption sites and (ii) desorption of phosphorous via surface complexation reactions due to pH changes during the experiment.

  16. Pb isotopes in sediments of Lake Constance, Central Europe constrain the heavy metal pathways and the pollution history of the catchment, the lake and the regional atmosphere

    SciTech Connect

    Kober, B.; Wessels, M.; Bollhoefer, A.; Mangini

    1999-05-01

    Pb isotope ratios and Pb concentrations of well-dated sediments of Lake Constance, Central Europe have been analyzed using thermal ion mass spectrometry. Sequential extraction studies indicated isotope homogeneity of the leachable Pb components within the investigated layers. Since the middle of the 19th century a significant anthropogenic Pb component appeared in the lake sediments, and rapidly approaches concentration levels similar to that of the geogenic Pb background (20 ppm) at the beginning of the 20th century. Anthropogenic Pb was predominantly transferred to the lake sediments via the atmosphere. Pb sources were coal combustion, industrial ore processing and leaded gasoline. The flux of a fluvial Pb component to the lake sediments, additive to atmospheric Pb deposition, peaked in about 1960. This flux is attributed to (re)mobilization of Pb from polluted parts of the lake catchment, and indicates the change of catchment soils from a pollution sink to a heavy metal source. The strong reduction of anthropogenic Pb in the uppermost lake sediments since the 1960s has been caused by advances of environmental protection. The lake sediments record the changing fluxes and the isotope composition of the deposited aeolian Pb pollution. During the 20th century aeolian Pb fluxes to the lake sediments were in the range of 1--4 {micro}g/cm{sup 2}/a. During peak emission periods of gasoline Pb to the atmosphere (1960--1990) the aerosol Pb isotope composition was rather constant ({sup 206}Pb/{sup 207}Pb: 1.12--1.13) and probably a mixture of Canadian and Australian with Russian and Central European Pb types. Aeolian Pb isotope and Pb flux trends in the lake sediments as a whole agree well with the trends found in Alpine glaciers (Doering et al., 1997a,b) and in ombrotrophic peat bogs of Switzerland (Shotyk et al., 1996). However, different industrial Pb components were deposited in the archives of aeolian pollution during the early 20th century.

  17. Recruitment of Total Phytoplankton, Chlorophytes and Cyanobacteria from Lake Sediments Recorded by Photosynthetic Pigments in a Large, Shallow Lake (Lake Taihu, China)

    NASA Astrophysics Data System (ADS)

    Cao, Huan-Sheng; Kong, Fan-Xiang; Tan, Jian-Kang; Zhang, Xiao-Feng; Tao, Yi; Yang, Zhou

    2005-08-01

    Recruitment of total phytoplankton, chlorophytes and cyanobacteria from lake sediments to the water column was studied using photosynthetic pigments at one site (1.5 m) in Lake Taihu, a large shallow lake in China. Samples were taken weekly from the migration traps installed on the bottom from March to May 2004. Abundance of total phytoplankton, chlorophytes and cyanobacteria were represented by Chlorophyll (Chl) a, b, and phycocyanin (PC), respectively. Over the three months, total phytoplankton, chlorophytes, and cyanobacteria corresponding to 48.9%, 68.9% and 316.2% of their initial concentrations in surface sediments were recruited in Lake Taihu. However, compared with their increase in pelagic abundance over the same period, the recruitment accounted for a rather small inoculum. Accompanying the recruitment, total phytoplankton and chlorophytes declined and cyanobacteria increased in the upper 0-2 cm sediments; colonies of Microcystis aeruginosa in the water column enlarged from small size with several cells to large colonies with hundreds of cells. Thus, overwintering and subsequent growth renewal of pelagic phytoplankton merits further study and comparison with benthic survival and recruitment.

  18. [Asylum and immigration in Germany].

    PubMed

    Angenendt, S

    1994-01-01

    "Germany, which used to be one of the most tolerant countries in matters concerning asylum, has, since the eighties, been confronted by very large migratory flows. Immigration to [West Germany] consisted every year of hundreds of thousands of asylum-seekers, a similar number of...Germans from Russia, Kazakhstan, Romania and Poland, as well as a large number of East Germans. On May 26th 1993, the Bundestag adopted a new law making asylum and immigration to Germany increasingly difficult. The problem of immigration has not been resolved, however, as is shown by the situation in the East European countries, Germany's neighbours, who are suffering the consequences of the new asylum policy...." (SUMMARY IN ENG)

  19. Indices of benthic community tolerance in contaminated Great Lakes sediments: Relations with sediment contaminant concentrations, sediment toxicity, and the sediment quality triad

    USGS Publications Warehouse

    Wildhaber, M.L.; Schmitt, C.J.

    1998-01-01

    We evaluated the toxic-units model developed by Wildhaber and Schmitt (1996) as a predictor of indices of mean tolerance to pollution (i.e., Lenat, 1993; Hilsenhoff, 1987) and other benthic community indices from Great Lakes sediments containing complex mixtures of environmental contaminants (e.g., polychlorinated biphenyls - PCBs, polycyclic aromatic hydrocarbons PAHs, pesticides, chlorinated dioxins, and metals). Sediment toxic units were defined as the ratio of the estimated pore-water concentration of a contaminant to its chronic toxicity as estimated by U.S. Environmental Protection Agency Ambient Water Quality Criteria (AWQC) or other applicable standard. The total hazard of a sediment to aquatic life was assessed by summing toxic units for all contaminants quantified. Among the benthic community metrics evaluated, total toxic units were most closely correlated with Lenat's (1993) and Hilsenhoff's (1987) indices of community tolerance (T(L), and T(H), respectively); toxic units accounted for 42% (T(L)) and 53% (T(H)) of variability in community tolerance as measured by Ponar grabs. In contrast, taxonomic richness and Shannon-Wiener diversity were not correlated (P > 0.05) with toxic units. Substitution of order- or family-level identifications for lowest possible (mostly genus- or species-) level identifications in the calculation of T(L) and T(H) indices weakened the relationships with toxic units. Tolerance values based on order- and family-level identifications of benthos for artificial substrate samples were more strongly correlated with toxic units than tolerance values for benthos from Ponar grabs. The ability of the toxic-units model to predict the other two components (i.e., laboratory-measured sediment toxicity and benthic community composition) of the Sediment Quality Triad (SQT) may obviate the need for the SQT in some situations.

  20. Spatial distribution and risk assessment of heavy metals and As pollution in the sediments of a shallow lake.

    PubMed

    Deng, Jiancai; Wang, Yuansheng; Liu, Xin; Hu, Weiping; Zhu, Jinge; Zhu, Lin

    2016-05-01

    The concentrations and spatial distributions of eight heavy metals in surface sediments and sediment core samples from a shallow lake in China were investigated to evaluate the extent of the contamination and potential ecological risks. The results showed that the heavy metal concentrations were higher in the northern and southwestern lake zones than those in the other lake zones, with lower levels of As, Hg, Zn, Cu, Pb, Cr, and Ni primarily observed in the central and eastern lake regions and Cd primarily confined to areas surrounding the lake. The concentrations of the eight heavy metals in the sediment profiles tended to decrease with increasing sediment depth. The contents of Ni, Cu, Zn, Pb, and Cd in the surface sediment were approximately 1.23-18.41-fold higher than their background values (BVs), whereas the contents of Cr, As, and Hg were nearly identical to their BVs. The calculated pollution load index (PLI) suggested that the surface sediments of this lake were heavily polluted by these heavy metals and indicated that Cd was a predominant contamination factor. The comprehensive potential ecological risk index (PERI) in the surface sediments ranged from 99.2 to 2882.1, with an average of 606.1. Cd contributed 78.7 % to the PERI, and Hg contributed 8.4 %. Multivariate statistical analyses revealed that the surface sediment pollution with heavy metals mainly originated from industrial wastewater discharged by rivers located in the western and northwestern portion of the lake.

  1. Sediment-quality assessment of Franklin D. Roosevelt Lake and the upstream reach of the Columbia River, Washington, 1992

    USGS Publications Warehouse

    Bortleson, Gilbert Carl; Cox, S.E.; Munn, M.D.; Schumaker, R.J.; Block, E.K.

    2001-01-01

    Elevated concentrations of trace elements were found in bed sediment of Lake Roosevelt and the Columbia River, its principal source of inflow. Trace-element concentrations in whole water samples did not exceed criteria for freshwater organisms. Bed sediments of Lake Roosevelt were analyzed for organic compounds associated with wood-pulp waste. Dioxins and furans were found in suspended sediment and water of the Columbia River. Abundance and diversity of benthic invertebrate communities were analyzed.

  2. Sedimentation and Occurrence and Trends of Selected Chemical Constituents in Bottom Sediment, Empire Lake, Cherokee County, Kansas, 1905-2005

    USGS Publications Warehouse

    Juracek, Kyle E.

    2006-01-01

    For about 100 years (1850-1950), the Tri-State Mining District in parts of southeast Kansas, southwest Missouri, and northeast Oklahoma was one of the primary sources of lead and zinc ore in the world. The mining activity in the Tri-State District has resulted in substantial historical and ongoing input of cadmium, lead, and zinc to the environment including Empire Lake in Cherokee County, southeast Kansas. The environmental contamination caused by the decades of mining activity resulted in southeast Cherokee County being listed on the U.S. Environmental Protection Agency's National Priority List as a superfund hazardous waste site in 1983. To provide some of the information needed to support efforts to restore the ecological health of Empire Lake, a 2-year study was begun by the U.S. Geological Survey in cooperation with the U.S. Fish and Wildlife Service and the Kansas Department of Health and Environment. A combination of sediment-thickness mapping and bottom-sediment coring was used to investigate sediment deposition and the occurrence of cadmium, lead, zinc, and other selected constituents in the bottom sediment of Empire Lake. The total estimated volume and mass of bottom sediment in Empire Lake were 44 million cubic feet and 2,400 million pounds, respectively. Most of the bottom sediment was located in the main body and the Shoal Creek arm of the reservoir. Minimal sedimentation was evident in the Spring River arm of the reservoir. The total mass of cadmium, lead, and zinc in the bottom sediment of Empire Lake was estimated to be 78,000 pounds, 650,000 pounds, and 12 million pounds, respectively. In the bottom sediment of Empire Lake, cadmium concentrations ranged from 7.3 to 76 mg/kg (milligrams per kilogram) with an overall median concentration of 29 mg/kg. Compared to an estimated background concentration of 0.4 mg/kg, the historical mining activity increased the median cadmium concentration by about 7,200 percent. Lead concentrations ranged from 100 to

  3. Water volume and sediment accumulation in Lake Linganore, Frederick County, Maryland, 2009

    USGS Publications Warehouse

    Sekellick, Andrew J.; Banks, S.L.

    2010-01-01

    To assist in understanding sediment and phosphorus loadings and the management of water resources, a bathymetric survey was conducted at Lake Linganore in Frederick County, Maryland in June 2009 by the U.S. Geological Survey, in cooperation with the City of Frederick and Frederick County, Maryland. Position data and water-depth data were collected using a survey grade echo sounder and a differentially corrected global positioning system. Data were compiled and edited using geographic information system software. A three-dimensional triangulated irregular network 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 City of Frederick and digitized. The two surfaces were compared and a sediment volume was calculated. Cartographic representations of both water depth and sediment accumulation were produced along with an area/capacity table. An accuracy assessment was completed on the resulting bathymetric model. Vertical accuracy at the 95-percent confidence level for the collected data, the bathymetric surface model, and the bathymetric contour map was calculated to be 0.95 feet, 1.53 feet, and 3.63 feet, respectively. The water storage volume of Lake Linganore was calculated to be 1,860 acre-feet at full pool elevation. Water volume in the reservoir has decreased by 350 acre-feet (about 16 percent) in the 37 years since the dam was constructed. The total calculated volume of sediment deposited in the lake since 1972 is 313 acre-feet. This represents an average rate of sediment accumulation of 8.5 acre-feet per year since Linganore Creek was impounded. A sectional analysis of sediment distribution indicates that the most upstream third of Lake Linganore contains the largest volume of sediment whereas the section closest to the dam contains the largest amount of water. In comparison to other Maryland Piedmont reservoirs, Lake Linganore

  4. Sediment Coring of the Proglacial Lake Donguz-Orun (northern Caucasus, Russia)

    NASA Astrophysics Data System (ADS)

    Alexandrin, Mikhail; Solomina, Olga; Kalugin, Ivan; Darin, Andrey; Nesje, Atle

    2014-05-01

    So far, no high-resolution reconstructions of climate and glacier variations based on lake sediment properties are available in Caucasus Mountains. In other presently glaciated regions this approach is proved to be very useful for this purpose (e.g. Nesje et al., 2001, 2011; Bakke, 2005, Nesje, 2009) In this paper we report the first results of the sediment coring of Donguz-Orun Lake (N 43°13'26", E 42°29'35") situated in the upper reaches of Donguz-Orun-Kyol, a tributary of Baksan river in the Elbrus region of Northern Caucasus, a typical proglacial lake dammed by a lateral moraine deposited by the Donguz-Orun Glacier. It is a drainage lake with several inflowing glacial streams and effluent river Donguz-Orun. The surface area is around 105 000 m2 with a water volume of 465 000m3. The average water depth is around 4.5 m, with a maximum water depth of 14 m. The deepest part is found close to the moraine dam in the narrow northern part of the lake. This is normally consistent with this type of glacial lake systems. An intensive gravitational drift of the moraine material towards the lake is observed. These non-rounded moraine boulders constitute a significant part of the lakebed. Lacustrine sediments are present though. The coring campaign from Institute of Geography, Russian Academy of Sciences (August 2012) used a modified piston corer with a 110 mm-diameter plastic tube (Nesje, 1992) mounted on the inflatable catamaran to obtain lake sediments from Lake Donguz-Orun. A 28-cm long core was retrieved from a water depth of around 7 m. The sediments consist of regularly laminated, fine beige clay, with several interlayers of sand. The coring process appeared to be challenging due to the stiffness of clay, which led to extreme bending of the sediment layers in the basal part of the core. The original thickness of the sediments was obviously higher than observed in the core. In order to clarify the recent history of the Donguz-Orun glacier, we used lichenometry and

  5. Chemical and mineralogical proxies of erosion episodes in the dried lake sediments (Amik Lake, Southern Turkey): paleoenvironmental implications

    NASA Astrophysics Data System (ADS)

    El Ouahabi, Meriam; Hubert-Ferrari, Aurélia; Lebeau, Héléne; Fagel, Nathalie; Vander Auwera, Jacquelinec; Karabacak, Volkan; Schmidt, Sabine

    2016-04-01

    The Amik Basin in the Eastern Mediterranean region has been continuously occupied since 6000-7000 BC. The landscape has sustained with highly variable anthropic pressure culminating during the Late Roman Period when the Antioch city reached its golden age. The basin also sustained a high seismic activity (M≥7) as it is a releasing step-over along the Dead Sea Fault. The study focuses on the sedimentary record of the Amik Lake occupying the central part of the Basin. Our objective is to constrain major paleo-environmental changes in the area over the last 4000 years and to unravel possible human impacts on the sedimentation. A diverse array of complementary methods was applied on the 6 m long record. High resolution of mineralogical (XRD) and geochemical (XRF) analyses were performed. Quantitative mineralogical phases of sediments by the Rietveld method were computed using Topaz software. The age of the record is constrained combining radionuclide and radiocarbon dating, and checked using the correlation between the earthquake history and rapidly deposited layer identified. A high sedimentation rate of 0.12 cm/yr was inferred at the coring site. The 4000 years old record shows that significant fluctuations of the lake level and the riverine system inflow into the Amik Lake occurred. The Late Bronze lowstand leaded to punctual dryings of the lake at the end of the Bronze/Iron transition marked by the collapse of the Hittite Empire and during the Dark ages. At that time, the riverine was carrying a large terrigenous input linked to strong soil erosion related to deforestation, exploitation of mineral resources and the beginning of upland cultivation. During the Roman Period and in the later periods, upland soils were partly depleted and the riverine system completely transformed by channelization that leaded to a mashification of the Amik Basin. Chemical and mineralogical composition of sediments is quite diversified reflecting the significant geological variation

  6. Using lead isotopes and trace element records from two contrasting Lake Tanganyika sediment cores to assess watershed – Lake exchange

    USGS Publications Warehouse

    Odigie, Kingsley; Cohen, A.D.; Swarzenski, Peter W.; Flegal, R

    2014-01-01

    Lead isotopic and trace element records of two contrasting sediment cores were examined to reconstruct historic, industrial contaminant inputs to Lake Tanganyika, Africa. Observed fluxes of Co, Cu, Mn, Ni, Pb, and Zn in age-dated sediments collected from the lake varied both spatially and temporally over the past two to four centuries. The fluxes of trace elements were lower (up to 10-fold) at a mid-lake site (MC1) than at a nearshore site (LT-98-58), which is directly downstream from the Kahama and Nyasanga River watersheds and adjacent to the relatively pristine Gombe Stream National Park. Trace element fluxes at that nearshore site did not measurably change over the last two centuries (1815–1998), while the distal, mid-lake site exhibited substantial changes in the fluxes of trace elements – likely caused by changes in land use – over that period. For example, the flux of Pb increased by ∼300% from 1871 to 1991. That apparent accelerated weathering and detrital mobilization of lithogenic trace elements was further evidenced by (i) positive correlations (r = 0.77–0.99, p < 0.05) between the fluxes of Co, Cu, Mn, Ni, Pb, and Zn and those of iron (Fe) at both sites, (ii) positive correlations (r = 0.82–0.98, p < 0.01, n = 9) between the fluxes of elements (Al, Co, Cu, Fe, Mn, Ni, Pb, and Zn) and the mass accumulation rates at the offshore site, (iii) the low enrichment factors (EF < 5) of those trace elements, and (iv) the temporal consistencies of the isotopic composition of Pb in the sediment. These measurements indicate that accelerated weathering, rather than industrialization, accounts for most of the increases in trace element fluxes to Lake Tanganyika in spite of the development of mining and smelting operations within the lake’s watershed over the past century. The data also indicate that the mid-lake site is a much more sensitive and useful recorder of environmental changes than the nearshore site. Furthermore, the lead isotopic compositions

  7. Dynamics of suspended sediment plumes in Lake Ontario

    NASA Technical Reports Server (NTRS)

    Pluhowski, E. J. (Principal Investigator)

    1974-01-01

    The author has identified the following significant results. Two unusual turbidity features were detected in imagery obtained over Lake Ontario on September 19, 1973. The location of a submerged sewer outfall was detected in frame 1423-15224-5 about 2 kilometers offshore opposite a treatment plant serving Rochester, New York. The other feature was a thermal heat plume made visible by an erosive eastward moving longshore current. The thermal plume, which extended about 3 kilometers into the lake, results from the discharge of cooling water from a nuclear power plant located 20 miles east of Rochester, New York. Under an offshore wind field, the outer edge of the Niagara River plume extended 30 kilometers into Lake Ontario on September 3, 1973. By way of contrast, a strong west-northwest wind on April 29, 1973, confined the plume to about 3 kilometers of the lake's south shore. The size of the Genesee River plume is largely dependent on discharge. During the spring high flow season, the plume extended over 22 square kilometers of the lake's surface on May 16, 1973. As runoff dwindled with the approach of summer, the plume contracted to less than 1 square kilometer in area by mid-July.

  8. Alkylphenols, polycyclic aromatic hydrocarbons, and organochlorines in sediment from Lake Shihwa, Korea: Instrumental and bioanalytical characterization

    SciTech Connect

    Khim, J.S.; Villeneuve, D.L.; Kannan, K.; Lee, K.T.; Snyder, S.A.; Koh, C.H.; Giesy, J.P.

    1999-11-01

    Lake Shihwa is an artificial lake, located on the west coast of Korea, that has experienced environmental deterioration since 1994, when it was formed by construction of a sea dike. This study used instrumental analysis and in vitro bioassays to characterize organic contaminants in sediment collected from 11 stations on Lake Shihwa. Alkylphenol (AP) concentrations in Lake Shihwa sediment ranged from 20.2 to 1,820 ng/g nonylphenol and from 4.69 to 50.5 ng/g octylphenol, on a dry weight basis. Maximum concentrations of polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides, and polychlorinated biphenyls (PCBs) were 30.8, 2.26, and 12.3 ng/g (dry weight), respectively. Significant estrogenic activity was associated with fractions containing APs. Mass-balance analysis suggested that reported concentrations of APs account for less than 20% of the estrogenic activity observed. No significant dioxin like activity was associated with fractions containing classic aryl hydrocarbon receptor agonists, such as PCBs, but the mid-polarity fractions containing PAHs and most polar fractions yielded significant dioxin like activity. Overall, most of the in vitro bioassay responses appear to have been caused by unidentified and/or undetectable compounds associated with Lake Shihwa sediment.

  9. Trimethylamine stimulated and dissolved organic matter inhibited methane production in sediment from the Poyang Lake, China.

    PubMed

    Wang, Jiajia; Liu, Chunying; Gong, Xiaofeng; Liu, Yuanmu; Chen, Chunli

    2016-10-01

    Methane (CH4) emitted from wetlands contributes significantly to the greenhouse effect. The Poyang Lake, the largest freshwater lake in China, is fed by five rivers and connects to the Yangtze River. The area of the lake fluctuates dramatically between drawdown and flood periods with large areas of wetlands. In order to understand the CH4 production capacity and factors that influence CH4 production in the wetland, a static closed chamber combined with a gas chromatograph technique was used to investigate the influence of substrates and electron acceptors on methanogenesis. The results showed that CH4 production capacity of sediments from the Poyang Lake was [Formula: see text] and it was stimulated by trimethylamine (TMA) to a great extent. Incubation temperature played a vital role on CH4 production in sediments and the optimum temperature for methanogenesis was 35°C. Minimum CH4 production capacity occurred with the addition of FeCl3, and the inhibitory effects of electron acceptors decreased in the sequence: FeCl3 > MnO2 > DOM > Fe2O3. In this study, DOM was demonstrated as one of the inhibitors to methanogenesis and TMA was the main substrate of methanogens in the sediments of the Poyang Lake whose pH value is 7.83.

  10. Sedimentary processes in High Arctic lakes (Cape Bounty, Melville Island, Canada): What do sediments really record?

    NASA Astrophysics Data System (ADS)

    Normandeau, Alexandre; Lamoureux, Scott; Lajeunesse, Patrick; Francus, Pierre

    2016-04-01

    Lacustrine sedimentary sequences can hold a substantial amount of information regarding paleoenvironments, hydroclimate variability and extreme events, providing critical insights into past climate change. The study of lacustrine sediments is often limited to the analysis of sediment cores from which past changes are inferred. However, studies have provided evidence that the accumulation of sediments in lacustrine basins and their distribution can be affected by a wide range of internal and external forcing mechanisms. It is therefore crucial to have a good knowledge of the factors controlling the transport and distribution of sediments in lakes prior to investigating paleoenvironmental archives. To address this knowledge gap, the Cape Bounty Arctic Watershed Observatory (CBAWO), located on southern Melville Island in the Canadian High Arctic, was initiated in 2003 as a long term monitoring site with the aim of understanding the controls over sediment transport within similar paired watersheds and lakes. The East and West lakes have been monitored each year since 2003 to document the role of hydro-climate variability on water column processes and sediment deposition. Moorings recording water electrical conductivity, temperature, density, dissolved oxygen and turbidity, as well as sediment traps were deployed during the active hydrological period (generally May-July). These data were analyzed in combination with hydrological and climatic data from the watersheds. Additionally, a high-resolution bathymetric and sub-bottom survey was completed in 2015 and allowed imaging the lake floor and sub-surface in great detail. This combination of process and lake morphological data are unique in the Arctic. The morphostratigraphic analysis reveals two highly disturbed lake floors, being widely affected by subaqueous mass movements that were triggered during the last 2000 years. Backscatter intensity maps and the presence of bedforms on each delta foresets indicate that

  11. Temporal correlation of U. S. Great Basin lake sediments below the Mono Lake Excursion using paleomagnetic secular variation

    NASA Astrophysics Data System (ADS)

    Liddicoat, J. C.; Coe, R. S.; Negrini, R. M.; Knott, J. R.; Lund, S.; Benson, L. V.

    2015-12-01

    Beginning nearly 50 years ago with a paleomagnetic study of exposed lacustrine sediments in the Mono Basin, CA (Denham and Cox, 1971), there have been subsequent studies to document paleomagnetic secular variation (PSV) in the basin and to establish a chronology for that record (Vazquez and Lidzbarski, 2012). We report a paleomagnetic secular variation (PSV) investigation of lacustrine sediments in the Mono Basin, CA, that extends the base of the PSV record of Lund et al. (1988) by about 20 percent. We did our investigation at two localities separated by about 4 km on the southeastern and eastern sides of Mono Lake: South Shore Cliffs (SSC) and Warm Springs (WS). The sampled interval at SSC is from 0.1 m above to 2.2 m below Wilson Creek Ash 19 in the tephrostratigraphy of Lajoie (1968), ending in loose sand. At WS, we sampled from Ash 17 to 1.0 m below Ash 19, a total of 2 m. At SSC using back-to-back horizons 2-cm thick containing one to three samples each that were a.f. or thermally demagnetized, we found rapidly fluctuating PSV in the interval from ~ 0.3 to 1.0 m below Ash 19. The fluctuating PSV contains a change in declination of ~ 80˚ from 308˚ (n = 3, α-95: 6.1˚) to 29˚ (n = 3, α-95: 11.5˚) within a single hand sample that spans 14 cm. Inclination during that change in declination gradually rose from 56˚ to 63˚ and increased to 70˚ before reducing to a minimum of 29.9˚. The path of the Virtual Geomagnetic Poles when the declination is most westerly forms a narrow loop that reaches 49.7˚ N latitude near 170˚ E longitude. At WS the westerly swing in declination is absent, but the easterly declination and relatively steep inclination described above are recorded. A study of the relative paleomagnetic intensity (RPI) shows that the maximum RPI is ~1.5 m below Ash 19 and decreases to a minimum ~6 cm above the ash. Distinct PSV and RPI features below the Mono Lake excursion correlate well between records from the periphery of Mono Lake and those from

  12. Ecosystem regime change inferred from the distribution of trace metals in Lake Erie sediments

    PubMed Central

    Yuan, Fasong; Depew, Richard; Soltis-Muth, Cheryl

    2014-01-01

    Many freshwater and coastal marine ecosystems across the world may have undergone an ecosystem regime change due to a combination of rising anthropogenic disturbances and regional climate change. Such a change in aquatic ecosystems is commonly seen as shifts in algal species. But considerably less detail is known about the eutrophication history in terms of changes in algal productivity, particularly for a large lake with a great deal of spatial variability. Here we present an analysis of trace metals (Cu, Ni, Cd, and Pb) on a sediment core recovered from Lake Erie, off the Vermilion coast of northern Ohio, USA, to reconstruct the eutrophication history of the lake over the past 210 years. Following a slow eutrophication during European settlement, Lake Erie experienced a period of accelerated eutrophication, leading to an ecosystem regime transition into a eutrophic lake state in 1950. Our results suggested that the lake's biological productivity has ever since maintained fairly high even though a significant input reduction was realized from rigorous nutrient abatements that began as early as in 1969. This work underscored the role of in-lake biogeochemical cycling in nutrient dynamics of this already eutrophic lake. PMID:25434300

  13. Bathymetric mapping, sediment quality, and water quality of Lake Delhi, Iowa, 2001-02

    USGS Publications Warehouse

    Schnoebelen, Douglas J.; McVay, Jason C.; Barnes, Kymm K.; Becher, Kent D.

    2003-01-01

    Water-quality sampling results indicate areas affected by elevated nutrient and bacteria concentrations in the lake and tributary streams. The tributary streams had the highest median nitrate concentrations (12.1 milligrams per liter) when compared to median nitrate concentrations in the lake (8.7 milligrams per liter) or the Maquoketa River (10.5 milligrams per liter). The maximum nitrate concentrations detected for Maquoketa River, lake, and tributary sites were 13.5, 13.5, and 18.6 milligrams per liter, respectively. Nitrate concentrations in the late summer decreased from 2 Bathymetric Mapping, Sediment Quality, and Water Quality of Lake Delhi, Iowa, 2001–02 the upstream (7.8 milligrams per liter) to the downstream (5.0 milligrams per liter) one-third of Lake Delhi and most likely were the result of uptake of nitrate by algae and aquatic biota in the lake. Median concentrations of total coliform and E. coli bacteria for the lake sites were 450 and 17 colonies per 100 milliliters of sample, respectively. The U.S. Environmental Protection Agency criteria for full body contact (swimming or bathing) are 200 colonies per 100 milliliters for fecal bacteria and 126 colonies per 100 milliliters for E. coli bacteria. The highest bacteria concentrations in the lake occurred after a rain and were 25,000 colonies per 100 milliliters total coliform and 1,900 colonies per 100 milliliters E. coli.

  14. Ecosystem regime change inferred from the distribution of trace metals in Lake Erie sediments.

    PubMed

    Yuan, Fasong; Depew, Richard; Soltis-Muth, Cheryl

    2014-12-01

    Many freshwater and coastal marine ecosystems across the world may have undergone an ecosystem regime change due to a combination of rising anthropogenic disturbances and regional climate change. Such a change in aquatic ecosystems is commonly seen as shifts in algal species. But considerably less detail is known about the eutrophication history in terms of changes in algal productivity, particularly for a large lake with a great deal of spatial variability. Here we present an analysis of trace metals (Cu, Ni, Cd, and Pb) on a sediment core recovered from Lake Erie, off the Vermilion coast of northern Ohio, USA, to reconstruct the eutrophication history of the lake over the past 210 years. Following a slow eutrophication during European settlement, Lake Erie experienced a period of accelerated eutrophication, leading to an ecosystem regime transition into a eutrophic lake state in 1950. Our results suggested that the lake's biological productivity has ever since maintained fairly high even though a significant input reduction was realized from rigorous nutrient abatements that began as early as in 1969. This work underscored the role of in-lake biogeochemical cycling in nutrient dynamics of this already eutrophic lake.

  15. Ecosystem regime change inferred from the distribution of trace metals in Lake Erie sediments

    NASA Astrophysics Data System (ADS)

    Yuan, Fasong; Depew, Richard; Soltis-Muth, Cheryl

    2014-12-01

    Many freshwater and coastal marine ecosystems across the world may have undergone an ecosystem regime change due to a combination of rising anthropogenic disturbances and regional climate change. Such a change in aquatic ecosystems is commonly seen as shifts in algal species. But considerably less detail is known about the eutrophication history in terms of changes in algal productivity, particularly for a large lake with a great deal of spatial variability. Here we present an analysis of trace metals (Cu, Ni, Cd, and Pb) on a sediment core recovered from Lake Erie, off the Vermilion coast of northern Ohio, USA, to reconstruct the eutrophication history of the lake over the past 210 years. Following a slow eutrophication during European settlement, Lake Erie experienced a period of accelerated eutrophication, leading to an ecosystem regime transition into a eutrophic lake state in 1950. Our results suggested that the lake's biological productivity has ever since maintained fairly high even though a significant input reduction was realized from rigorous nutrient abatements that began as early as in 1969. This work underscored the role of in-lake biogeochemical cycling in nutrient dynamics of this already eutrophic lake.

  16. 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 ...

  17. EVALUATING METHODS FOR ASSESSING SEDIMENT QUALITY IN A GREAT LAKES EMBAYMENT

    EPA Science Inventory

    This manuscript evaluates a probability based sampling study of sediment quality in a Great Lakes Area of Concern (AOC). Results of this study will be used to establish monitoring benchmarks and clean-up targets for contaminated sites in the region.

  18. Application of PAH concentration profiles in lake sediments as indicators for smelting activity.

    PubMed

    Warner, Wiebke; Ruppert, Hans; Licha, Tobias

    2016-09-01

    The ability of lake sediment cores to store long-term anthropogenic pollution establishes them as natural archives. In this study, we focus on the influence of copper shale mining and smelting in the Mansfeld area of Germany, using the depth profiles of two sediment cores from Lake Süßer See. The sediment cores provide a detailed chronological deposition history of polycyclic aromatic hydrocarbons (PAHs) and heavy metals in the studied area. Theisen sludge, a fine-grained residue from copper shale smelting, reaches the lake via deflation by wind or through riverine input; it is assumed to be the main source of pollution. To achieve the comparability of absolute contaminant concentrations, we calculated the influx of contaminants based on the sedimentation rate. Compared to the natural background concentrations, PAHs are significantly more enriched than heavy metals. They are therefore more sensitive and selective for source apportionment. We suggest two diagnostic ratios of PAHs to distinguish between Theisen sludge and its leachate: the ratio fluoranthene to pyrene ~2 and the ratio of PAH with logKOW<5.7 to PAH with a logKOW>5.7 converging to an even lower value than 2.3 (the characteristic of Theisen sludge) to identify the particulate input in lake environments.

  19. ASSESSMENT OF MERCURY IN HYPOLIMNETIC LAKE SEDIMENTS OF VERMONT AND NEW HAMPSHIRE

    EPA Science Inventory

    The research is to characterize concentrations of total methylmercury in waters and surficial sediments of Vermont and New Hampshire lakes, and to relate these data to commonly measured water column chemical parameters and watershed-level physical attributes. The primary goal of...

  20. A model of microbial activity in lake sediments in response to periodic water-column mixing.

    PubMed

    Gantzer, Charles J; Stefan, Heinz G

    2003-07-01

    Under stagnant conditions, the mass transport of a soluble substrate from a lake's water column to the sediment/water interface is limited by molecular diffusion. Stagnant conditions coupled with a continuing sediment biological demand create a substrate depletion zone above the sediment/water interface. The frequency at which the substrate depletion zone is destroyed by internal seiches and other intermittent flow phenomena influences the time-averaged substrate concentration at the sediment/water interface. A more frequent mixing results in a greater time-averaged interface concentration and consequently affects the amount of microbial biomass that can be supported in the lake sediments and the flux of the substrate into the sediment. A one-dimensional, two-substrate model is used to examine the impact of mixing frequency on the activity of sulfate-reducing bacteria (SRB) in lake sediments. In the model, sulfate is supplied from the water column, while acetate is generated within the sediments. Mass transport to and within the sediments is by molecular diffusion except for instantaneous mixing events. Between mixing events, sulfate concentration gradients form above the sediment/water interface in the diffusive boundary layer. Sulfate depletion zones can be centimeters thick. When typical biological rate and diffusion coefficients for sulfate and acetate are used as inputs, the model indicates that a more frequent water-column mixing results in greater SRB concentrations. For an assumed bulk water-column sulfate concentration of 4.8 mg x l(-1), the sediment SRB concentrations for the modeled hourly, 6-hourly, daily, and weekly mixing frequencies were 175, 136, 91, and 30 mg x m(-2), respectively. The model also predicts higher time-averaged sulfate flux rates at more frequent water-column mixing. The time-averaged sulfate flux rates for the hourly, 6-hourly, daily, and weekly mixing frequencies were 1.26, 1.13, 0.78, and 0.30 mg x m(-2)h(-1), respectively. Thus

  1. Expressions of climate perturbations in western Ugandan crater lake sediment records during the last 1000 yr

    NASA Astrophysics Data System (ADS)

    Mills, K.; Ryves, D. B.; Anderson, N. J.; Bryant, C. L.; Tyler, J. J.

    2013-09-01

    Equatorial East Africa has a complex, regional patchwork of climate regimes, with multiple interacting drivers. Recent studies have focussed on large lakes and reveal signals that are smoothed in both space and time, and, whilst useful at a continental scale, are of less relevance when understanding short-term, abrupt or immediate impacts of climate and environmental changes. Smaller-scale studies have highlighted spatial complexity and regional heterogeneity of tropical palaeoenvironments in terms of responses to climatic forcing (e.g. the Little Ice Age [LIA]) and questions remain over the spatial extent and synchroneity of climatic changes seen in East African records. Sediment cores from paired crater lakes in western Uganda were examined to assess ecosystem response to long-term climate and environmental change as well as testing responses to multiple drivers using redundancy analysis. These archives provide annual to sub-decadal records of environmental change. The records from the two lakes demonstrate an individualistic response to external (e.g. climatic) drivers, however, some of the broader patterns observed across East Africa suggest that the lakes are indeed sensitive to climatic perturbations such as a dry Mediaeval Climate Anomaly (MCA; 1000-1200 AD) and a relatively drier climate during the main phase of the LIA (1500-1800 AD); though lake levels in western Uganda do fluctuate. The relationship of Ugandan lakes to regional climate drivers breaks down c. 1800 AD, when major changes in the ecosystems appear to be a response to sediment and nutrient influxes as a result of increasing cultural impacts within the lake catchments. The data highlight the complexity of individual lake response to climate forcing, indicating shifting drivers through time. This research also highlights the importance of using multi-lake studies within a landscape to allow for rigorous testing of climate reconstructions, forcing and ecosystem response.

  2. Cliff-nesting seabirds influence production and sediment chemistry of lakes situated above their colony.

    PubMed

    Hargan, K E; Michelutti, N; Coleman, K; Grooms, C; Blais, J M; Kimpe, L E; Gilchrist, G; Mallory, M; Smol, J P

    2017-01-15

    Seabirds that congregate in large numbers during the breeding season concentrate marine-derived nutrients to their terrestrial nesting sites, and these nutrients disperse and enhance production in nearby terrestrial, freshwater and marine ecosystems. In the Canadian Arctic, large seabird colonies (>100,000 breeding pairs) nest on cliff faces that drain directly in the ocean, ultimately returning the nutrients back to the marine environment from which they were derived. However, strong winds blowing up cliff faces could transport nutrients up in elevation and onto surrounding terrestrial and aquatic environments. Here, we assess the degree to which seabird nutrients and metals have been delivered to coastal lakes near Hudson Strait (Nunavut, Canada) over the past century. Three lakes located at a higher elevation and increasing distance from a thick-billed murre (Uria lomvia) colony (~400,000 breeding pairs) were sampled for surface water chemistry. In addition, algal assemblages, nitrogen isotopes, and metal/metalloids were analyzed in four dated sediment cores. Elevated nutrients and major ions, as well as an enriched δ(15)N signature in the sediment cores, were measured in the lake <100m from the cliff, whilst no comparable changes were recorded in lakes >1km from the seabird colony. In contrast, similar oligotrophic and benthic diatom assemblages were identified in all three lakes, suggesting that diatoms were not influenced by enhanced nutrient inputs in this Arctic environment. Chemical tracers (e.g., total mercury) and algal assemblages in the lake near the colony suggest climate warming since ~1950 was the most likely driver of limnological changes, but this effect was muted in the more distant lakes. These pronounced changes in the seabird-impacted lake suggest that, with warming air temperatures and diminished lake ice cover, longer growing seasons may allow for aquatic organisms to more fully exploit the seabird nutrient subsidies.

  3. Long livestock farming history and human landscape shaping revealed by lake sediment DNA.

    PubMed

    Giguet-Covex, Charline; Pansu, Johan; Arnaud, Fabien; Rey, Pierre-Jérôme; Griggo, Christophe; Gielly, Ludovic; Domaizon, Isabelle; Coissac, Eric; David, Fernand; Choler, Philippe; Poulenard, Jérôme; Taberlet, Pierre

    2014-01-01

    The reconstruction of human-driven, Earth-shaping dynamics is important for understanding past human/environment interactions and for helping human societies that currently face global changes. However, it is often challenging to distinguish the effects of the climate from human activities on environmental changes. Here we evaluate an approach based on DNA metabarcoding used on lake sediments to provide the first high-resolution reconstruction of plant cover and livestock farming history since the Neolithic Period. By comparing these data with a previous reconstruction of erosive event frequency, we show that the most intense erosion period was caused by deforestation and overgrazing by sheep and cowherds during the Late Iron Age and Roman Period. Tracking plants and domestic mammals using lake sediment DNA (lake sedDNA) is a new, promising method for tracing past human practices, and it provides a new outlook of the effects of anthropogenic factors on landscape-scale changes.

  4. Holocene glacier fluctuations inferred from lacustrine sediment, Emerald Lake, Kenai Peninsula, Alaska

    NASA Astrophysics Data System (ADS)

    LaBrecque, Taylor S.; Kaufman, Darrell S.

    2016-01-01

    Physical and biological characteristics of lacustrine sediment from Emerald Lake were used to reconstruct the Holocene glacier history of Grewingk Glacier, southern Alaska. Emerald Lake is an ice-marginal threshold lake, receiving glaciofluvial sediment when Grewingk Glacier overtops the topographic divide that separates it from the lake. Sub-bottom acoustical profiles were used to locate core sites to maximize both the length and resolution of the sedimentary sequence recovered in the 4-m-long cores. The age model for the composite sequence is based on 13 14C ages and a 210Pb profile. A sharp transition from the basal inorganic mud to organic-rich mud at 11.4 ± 0.2 ka marks the initial retreat of Grewingk Glacier below the divide of Emerald Lake. The overlaying organic-rich mud is interrupted by stony mud that records a re-advance between 10.7 ± 0.2 and 9.8 ± 0.2 ka. The glacier did not spill meltwater into the lake again until the Little Ice Age, consistent with previously documented Little Ice Ages advances on the Kenai Peninsula. The retreat of Grewingk Glacier at 11.4 ka took place as temperature increased following the Younger Dryas, and the subsequent re-advance corresponds with a climate reversal beginning around 11 ka across southern Alaska.

  5. Sediment fluxes of polycyclic aromatic hydrocarbons in European high altitude mountain lakes

    SciTech Connect

    Fernandez, P.; Vilanova, R.M.; Grimalt, J.O.

    1999-11-01

    Polycyclic aromatic hydrocarbons (PAH) were measured in superficial sediments from several high altitude mountain lakes for assessment of contemporary background PAH pollution levels in Europe. The sediments were obtained by gravity coring, and the upper 0--1 cm were analyzed by gas chromatography coupled to mass spectrometry. The parent PAH mixtures are very uniform irrespective of lake location, lake characteristics, and PAH load, corresponding to airborne combustion mixtures refractory to photooxidation and chemical degradation. The sedimentary fluxes are lowest in Lake Arresjoeen (Arctic area), 6.9 {micro}g/m{sup 2}yr, between 44 and 150 {micro}g/m{sup 2}yr in west and central Europe and very high, 960--1,700 {micro}g/m{sup 2}yr, in east Europe. Normalization of these values to TOC reflects a uniform pattern in correspondence with continental influence and east-west distribution. This pattern parallels the annual average atmospheric deposition fluxes of sulfate, pointing to combustion particles as the main way of PAH transport into these high altitude lakes. The lowest PAH/TOC ratios are found in the sites more distant from the continent, the westernmost locations constitute another group higher values are found in the Alps and Pyrenees, and the most polluted lakes are found in the Tatra mountains.

  6. Anthropogenic sources of arsenic and copper to sediments in a suburban lake, Northern Virginia.

    PubMed

    Rice, Karen C; Conko, Kathryn M; Hornberger, George M

    2002-12-01

    Mass balances of total arsenic and copper for a suburban lake in densely populated northern Virginia were calculated using date collected during 1998. Mass-balance terms were precipitation; stream inflow, including road runoff; stream outflow; and contributions from leaching of pressure-treated lumber. More mass of arsenic and copper was input to the lake than was output the 1998 lake-retention rates were 70% for arsenic and 20% for copper. The arsenic mass balance compared well with a calculated annual mass accumulation in the top 1 cm of the lake sediments; however, the calculated contribution of copper to the lake was insufficient to account for the amount of copper in this zone. Leaching experiments were conducted on lumber treated with chromated copper arsenate (CCA) to quantify approximate amounts of arsenic and copper contributed by this source. Sources to lake sediments included leaching of CCA-treated lumber (arsenic, 50%; copper, 4%), streamwater (arsenic, 50%; copper, 90%), and atmospheric deposition (arsenic, 1%; copper, 3%). Results of this study suggest that CCA-treated lumber and road runoff could be significant nonpoint sources of arsenic and copper, respectively, in suburban catchments.

  7. Anthropogenic sources of arsenic and copper to sediments in a suburban lake, Northern Virginia

    USGS Publications Warehouse

    Rice, Karen C.; Conko, Kathryn M.; Hornberger, George M.

    2002-01-01

    Mass balances of total arsenic and copper for a suburban lake in densely populated northern Virginia were calculated using data collected during 1998. Mass-balance terms were precipitation; stream inflow, including road runoff; stream outflow; and contributions from leaching of pressure-treated lumber. More mass of arsenic and copper was input to the lake than was output; the 1998 lake-retention rates were 70% for arsenic and 20% for copper. The arsenic mass balance compared well with a calculated annual mass accumulation in the top 1 cm of the lake sediments; however, the calculated contribution of copper to the lake was insufficient to account for the amount of copper in this zone. Leaching experiments were conducted on lumber treated with chromated copper arsenate (CCA) to quantify approximate amounts of arsenic and copper contributed by this source. Sources to lake sediments included leaching of CCA-treated lumber (arsenic, 50%; copper, 4%), streamwater (arsenic, 50%; copper, 90%), and atmospheric deposition (arsenic, 1%; copper, 3%). Results of this study suggest that CCA-treated lumber and road runoff could be significant nonpoint sources of arsenic and copper, respectively, in suburban catchments.

  8. Arsenic Movement From Sediment to Water: Microbes and Mobilization in a Contaminated Lake

    NASA Astrophysics Data System (ADS)

    Keimowitz, A. R.; Mailloux, B. J.; Chillrud, S. N.; Ross, J.; Wovkulich, K.; McNamara, P.; Alexandrova, E.; Thompson, L.

    2008-12-01

    Union Lake (Millville, NJ), a reservoir downstream from the Vineland Chemical Company Superfund site, has bottom sediments that are highly contaminated with arsenic (>1 g/kg). Offsite As transport was investigated. Because the lake is a result of damming, it is perched above the water table and therefore As transport may occur via downward movement of porewaters and/or groundwaters. Preliminary evidence for this was found in the form of iron flocculates enriched in As which were found in surface seeps downgradient of the dam. The possibility of As remobilization and/or off-site transport by seasonal anoxia of lake bottom- waters was also explored. Although historically, appreciable As was found in the water column of the lake (up to approximately 200 micrograms/L), As releases over the summers of 2007 and 2008 were negligible to modest with a maximum [As] of 23 micrograms/L. Arsenic mobilization from the contaminated sediments into surface waters of the reservoir are limited in part due to incomplete eutrophication and frequent overturning (approximately 1x/month in summer 2007) of this shallow lake, therefore conditions which promoted greater As release were explored in the laboratory. Field and laboratory samples were examined for changes in the microbial community using a variety of genetic techniques; these changes in microbial community were both a result of, and influenced, seasonal lake cycles.

  9. Perfluoroalkyl substances and extractable organic fluorine in surface sediments and cores from Lake Ontario.

    PubMed

    Yeung, Leo W Y; De Silva, Amila O; Loi, Eva I H; Marvin, Chris H; Taniyasu, Sachi; Yamashita, Nobuyoshi; Mabury, Scott A; Muir, Derek C G; Lam, Paul K S

    2013-09-01

    Fourteen perfluoroalkyl substances (PFASs) including short-chain perfluorocarboxylates (PFCAs, C4-C6) and perfluoroalkane sulfonates (PFSAs, C4 and C6) were measured in surface sediment samples from 26 stations collected in 2008 and sediment core samples from three stations (Niagara, Mississauga, and Rochester basins) collected in 2006 in Lake Ontario. Perfluorooctanesulfonate (PFOS), perfluorooctanoate (PFOA), perfluorononanoate (PFNA), perfluorodecanoate (PFDA), and perfluoroundecanoate (PFUnDA) were detected in all 26 surface sediment samples, whereas perfluorohexane sulfonate (PFHxS), perfluorooctane sulfonamide (FOSA), perfluorododecanoate (PFDoDA) and perfluorobutanoate (PFBA) were detected in over 70% of the surface sediment samples. PFOS was detected in all of the sediment core samples (range: 0.492-30.1ngg(-1) d.w.) over the period 1952-2005. The C8 to C11 PFCAs, FOSA, and PFBA increased in early 1970s. An overall increasing trend in sediment PFAS concentrations/fluxes from older to more recently deposited sediments was evident in the three sediment cores. The known PFCAs and PFSAs accounted for 2-44% of the anionic fraction of the extractable organic fluorine in surface sediment, suggesting that a large proportion of fluorine in this fraction remained unknown. Sediment core samples collected from Niagara basin showed an increase in unidentified organic fluorine in recent years (1995-2006). These results suggest that the use and manufacture of fluorinated organic compounds other than known PFCAs and PFSAs has diversified and increased.

  10. Photoproduction of dissolved organic carbon and inorganic nutrients from resuspended lake sediments.

    PubMed

    Hu, Bin; Wang, Peifang; Zhang, Nannan; Wang, Chao; Ao, Yanhui

    2016-11-01

    Sediments exposed to simulated solar radiation can serve as an important source of dissolved organic carbon (DOC) to surrounding waters. However, it is still unclear if dissolved nutrients can be photoproduced from lake sedimentary organic matter. In this study, a series of laboratory-based experiments was conducted to address the photoproduction of dissolved inorganic nutrients and DOC from resuspended Taihu Lake sediments. Dissolved inorganic nutrients and DOC were photoproduced after 8-h irradiation. The released NH4(+), NOx(-), and DOC levels ranged from 3.57 to 12.14, 1.43 to 6.43, and 24.17 to 69.17 μmol L(-1), respectively. The variation in the amount released indicated that sediment source had an effect on DOC and nutrient photorelease. More DOC and nutrients were released from higher concentration suspensions. However, due to the light absorption by suspended sediment, less DOC and nutrients were released from per gram of suspended sediment in high concentration suspensions. The decrease in DOC and increase in dissolved inorganic nitrogen during the last 2-h irradiation indicated that the photoproduction of inorganic nutrients proceeded via direct photodissolution of suspended sediments and subsequent photodegradation of the produced dissolved organic matter. Our results demonstrated that the photoproduction flux of NH4(+) and NOx(-) accounts for 12.3 and 6.5 % of wet deposition, respectively, which suggest that the photodissolution of suspended sediment could be a potential source of DOC and dissolved nutrients in shallow water ecosystems.

  11. 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.

  12. Surficial geology and distribution of post-impoundment sediment in Las Vegas Bay, Lake Mead

    USGS Publications Warehouse

    Twichell, David C.; Cross, VeeAnn A.; Rudin, Mark J.; Parolski, Kenneth F.; Rendigs, Richard R.

    2001-01-01

    Sidescan sonar imagery and seismic-reflection profiles were collected in the northwestern part of Las Vegas Bay to map the distribution and volume of sediment that has accumulated in this part of Lake Mead since impoundment. The mapping suggests that three ephemeral streams are the primary source of this sediment, and of these, Las Vegas Wash is the largest. Two deltas off the mouth of Las Vegas Wash formed at different lake elevations and account for 41% of the total volume of post-impoundment sediment within the study area. Deltas off the other two washes (Gypsum and Government) account for only 6% of the total volume. The sediment beyond the front of the deltas is primarily mud, and it only occurs in valley floors, where it forms a flat-lying blanket that is mostly less than 1.5 m thick. Although a thin layer, the fine-grained sediment accounts for approximately 53% of the total post-impoundment sediment volume of 5.7 x 106 m3 that has accumulated in the study area. This sediment appears to have been transported several kilometers from the river sources by density flows.

  13. The regularity of wind-induced sediment resuspension in Meiliang Bay of Lake Taihu.

    PubMed

    Wang, Jianjian; Pang, Yong; Li, Yiping; Huang, Yawen; Jia, Junjie; Zhang, Peng; Kou, Xiaopeng

    2014-01-01

    Contaminants released by wind-induced sediment resuspension could influence the water quality in shallow lakes. This study aims to reveal the quantitative relationship between wind speed (v) and sediment resuspension rate (r) in Meiliang Bay of Lake Taihu. The study was conducted in three steps. First, the in situ wind speed and current velocity were measured over a period of 2 days in Meiliang Bay to establish the relationship between wind and hydrodynamic conditions; second, an indoor experiment was conducted in a cylindrical simulator with sediment from the study area to determine sediment resuspension rates under different hydrodynamic conditions; and third, linkages between sediment resuspension and wind were determined. The average sediment resuspension rate was highly correlated with the wind speed (R(2) = 0.99), and was expressed by r = 20.72v(2.034) at wind speeds in the range of 0-14 m/s. The critical wind speed for sediment resuspension is about 7 m/s. Under these conditions, the average resuspension rate could reach 1,000 g/(m(2)d), with a total phosphorus release rate of 1.1 g/(m(2)d) and a total nitrogen release rate of 18.1 g/(m(2)d).

  14. Generating quantitative palaeoflood data from homogeneous lake sediments: a case-study from Brotherswater, northwest England

    NASA Astrophysics Data System (ADS)

    Schillereff, Daniel; Chiverrell, Richard; Macdonald, Neil; Hooke, Janet

    2016-04-01

    The scarcity of long-term hydrological data is a barrier to reliably determining the likelihood of floods becoming more frequent and/or intense in a warmer world. Lakes and their sediments are increasingly being used to reconstruct long-term, highly-resolved datasets of past floods but the ultimate goal, generating quantitative palaeohydrological data to augment flood frequency analyses, is a persistent challenge. To this end, ascertaining the autogenic and allogenic processes influencing the character and preservation potential of palaeoflood laminations and determining the minimum discharge at which a sedimentary imprint will be deposited in a particular system are two key precursors. Some success has been achieved at lakes containing annually-laminated sequences or where event layers exhibit well-defined lithological contacts. Many non-alpine and non-polar lakes, especially those in temperate regions, are instead characterised by visually-homogeneous, organic-rich sediments from which discrete flood laminations are difficult to discriminate. Working at Brotherswater, a small upland lake in northwest England, we have successfully demonstrated an approach to obtain flood frequency and magnitude data from this type of lake system by integrating a 16 month sediment trap deployment (CE 2013-2014) with the recent (CE 1962 - 2014) depositional record. The geochemical composition and end-member modelling of the trap data shed light on the seasonal variation in background sedimentation dynamics, specifically enhanced sediment supply during winter, spring diatom blooms and heightened summer productivity, which alter the signature of coarse-grained deposition in response to higher flows. Having pinpointed the characteristic flood end-member, comparison of the short-core palaeoflood reconstruction to local river discharge data was able to reveal the hydrological thresholds of this system: flood magnitudes calculated to have a four year recurrence interval are preserved in

  15. Assessment of priority phenolic compounds in sediments from an extremely polluted coastal wetland (Lake Maryut, Egypt).

    PubMed

    Khairy, Mohammed A

    2013-01-01

    Although high concentrations of trace organic pollutants were recorded along the Egyptian Mediterranean Coast and its corresponding coastal wetlands, no published data are available for the levels of phenolic compounds. Thus, this work aimed to investigate the levels of phenolic compounds in sediments of a heavily polluted coastal wetland (Lake Maryut, Egypt). For that purpose, a method was optimized for the extraction and detection of chlorophenols, methylphenols, and nitrophenols in sediments using GC-MS. Sediments were extracted with 0.1 M NaOH/methanol by sonication. Cleanup of sediment extracts using liquid-liquid extraction and SPE was found important to remove most of the interfering co-extracts. The proposed analytical methodology was validated by analysis of matrix spikes. Detection limits were 0.063-0.694 μg/kg dw for sediments. Good recoveries (70-110%) and precision values (RSD < 20%) were obtained from the fortification experiments at the parts per billion level in sediments. The method was applied to investigate the level of contamination with phenols in 19 sediment samples from Lake Maryut. Results revealed that higher concentrations were observed in the main basin (MB) of Lake Maryut affected by the discharge of effluents from a primary wastewater treatment plant, direct discharge of industrial effluents, domestic wastes, and agricultural effluents from Qalaa Drain (QD). Chlorophenols (CPs) were the major group detected in the lake sediments followed by methylphenols (MPs) and nitrophenols (NPs). CPs were dominated by 2-, 4-, and 3-chlorophenols. Concentrations of CPs were higher at the north and northwestern parts of the MB indicating the influence of industrial effluents discharged into the lake. On the other hand, higher concentrations of NPs were observed at the south and southwestern parts of the MB, which is subjected to the discharge of agricultural and domestic effluents via QD. Results of the risk assessment revealed that phenol, cresols

  16. Optimizing Standard Sequential Extraction Protocol With Lake And Ocean Sediments

    EPA Science Inventory

    The environmental mobility/availability behavior of radionuclides in soils and sediments depends on their speciation. Experiments have been carried out to develop a simple but robust radionuclide sequential extraction method for identification of radionuclide partitioning in sed...

  17. Late Quaternary Lake History of Hala Lake, Qinghai Province, China, Evidenced by Ostracod Assemblages and Sediment Properties in Multiple Sediment Records

    NASA Astrophysics Data System (ADS)

    YAN, Dada; Wuennemann, Bernd

    2014-05-01

    Hala Lake, a closed 65 m deep lake basin in the western Qilian Mountains, Qinghai Province, is considered a monitor of climate-driven hydrological and environmental changes during the past 24 kyr BP. The distribution patterns of ostracod assemblages, sediment-geochemical properties in four sediment records from different water depths and the unique limnological setting (green algae layer between 25 and 32 m water depth and seasonally anoxic conditions) enabled us to reconstruct four major phases of centennial-scale water depth fluctuations from the global Last Glacial Maximum (ca. 24 kyr BP) to the Present. Our results show that Hala Lake experienced a very shallow and small water body during the LGM and Late Glacial under cold and dry climate conditions. Rapid increase of water depth and contemporaneous lake expansion started at around 15 kyr BP (Phase I), most likely as a result of glacier melt due to the onset of climate warming. The lake reached >45 m water depth at around 13.5 kyr BP, followed by a decline (5-6 m) during the Younger Dryas spell (ca. 12 kyr BP), which may be attributed to a short-term return to cooler and drier conditions. During the early Holocene (Phase II), water depth increased again towards lake highstands close to its present level. Besides continued glacier melt supply, we assume that summer monsoon effective moisture contributed to the overall water budget, but remained relatively unstable, favoring water depth fluctuations of about 10-15 m. A pronounced lower water depth falls into the period between 9 and 8 kyr BP, perhaps the result of weak monsoon influence or its complete absence, although the warming trend continued towards its optimum at ca. 8-7 kyr BP. A distinct mass flow, most likely triggered by an earthquake, occurred during a lake lowstand between 8.1 kyr BP and 7.0 kyr BP. The mid-Holocene (Phase III) was characterized by deepened water between 7.5 and 4.5 kyr BP, interrupted by short-term declines at around 7 and 6

  18. Historical changes in the concentrations of polycyclic aromatic hydrocarbons (PAHs) in Lake Peipsi sediments.

    PubMed

    Punning, Jaan-Mati; Terasmaa, Jaanus; Vaasma, Tiit; Kapanen, Galina

    2008-09-01

    The distribution of 11 individual polycyclic aromatic hydrocarbons (PAHs) was analysed in a (210)Pb dated sediment core from the deepest area of Lake Peipsi and in four surface sediment samples taken from littoral areas. According to the concentrations in the core three groups of PAHs may be distinguished: (1) relatively stable concentrations of PAHs within the whole studied time interval; (2) very low concentrations in sediments accumulated before intensive anthropogenic impact (from 19th century up to the 1920s) following a slight increase and (3) an overall increase in PAH concentrations since the 1920s up to the present. Comprehensive analysis of PAHs in the core and monitoring data obtained in the 1980s together with the lithology of sediments show that an increase of anthropogenically induced PAHs correlates well with the history of fuel consumption in Estonia and speaks about atmospheric long-distance transport of PAHs. The continuous increase of PAH concentrations since the 1920s do not support the earlier hypothesis about the dominating impact of the oil shale fired power plants near the lake, because their emissions decreased significantly in the 1990s. The concentration of PAHs in the deep lake core sample correlates well with the content of organic matter, indicating absorption and co-precipitation with plankton in the sediment.

  19. A monotonically declining elevational pattern of bacterial diversity in freshwater lake sediments.

    PubMed

    Zeng, Jin; Zhao, Dayong; Li, Huabing; Huang, Rui; Wang, Jianjun; Wu, Qinglong L

    2016-12-01

    The distribution patterns of bacterial communities along elevational gradients remain unexplored in aquatic ecosystems. This study investigated the diversity and community composition of bacteria in the sediments of lakes along a mountainside elevational gradient from 525 to 4 490 m in western China. The bacterial alpha diversity (taxonomic richness and phylogenetic diversity) at different sediment depths decreased monotonically with the increasing elevation, and the beta diversity (dissimilarity between lakes) increased significantly with the increasing elevation distance. Both elevation and chemical variables including pH and carbon/nitrogen ratio were identified as major factors affecting the bacterial diversity. Especially, bacterial alpha/beta diversity was significantly related to both chemical and elevational gradients in the surface sediments, whereas elevation overwhelmed chemical factors in influencing the bacterial alpha/beta diversity in the subsurface sediments. Phylogenetic structure analysis demonstrated that environmental filtering was the most important process affecting the bacterial community assembly along the elevational gradient, and the strength of environmental filtering increased towards high elevations. In summary, we observed for the first time a monotonically decreasing elevational pattern in bacterial diversity of freshwater lake sediments, which is mainly driven by elevation associated environmental factors.

  20. Enhancement of anaerobic ammonium oxidation in lake sediment by applying drinking water treatment residuals.

    PubMed

    Wang, Ziyuan; Wang, Changhui; Wang, Zhixin; Pei, Yuansheng

    2013-08-01

    In this study, the effect of drinking water treatment residuals (WTRs), non-hazardous byproducts from drinking water treatment plants, on anaerobic ammonium oxidation (anammox) in lake sediments were investigated, qualitatively and quantitatively based on enrichment tests. The results suggested that after the enrichment, anammox were strengthened significantly in enriched sediments with no WTRs (ESNW) and with WTRs (ESW). Comparatively, anammox bacteria in ESW were more aggregated than ESNW. The activity (9.2 nmol g(-1)h(-1)) and abundance (9.8×10(7)copies g(-1)) of anammox bacteria in ESW were also higher than ESNW (6.1 nmol g(-1)h(-1)and 8.9×10(7) copies g(-1)). Further analysis suggested that after enrichment, anammox bacteria in sediments were phylogenetically more distant from Candidatus Kuenenia; anammox bacteria in ESW were closely related to Candidatus Brocadia. Overall, WTRs promoted aggregation, strengthened activity and increased abundance of anammox bacteria in lake sediments. Therefore, WTRs can enhance anammox in lake sediments.

  1. Modeling water and sediment contamination of Lake Pontchartrain following pump-out of Hurricane Katrina floodwater.

    PubMed

    Dortch, Mark S; Zakikhani, Mansour; Kim, Sung-Chan; Steevens, Jeffery A

    2008-05-01

    Levee failure and overtopping as a result of Hurricane Katrina caused major flooding of New Orleans, Louisiana. Floodwaters, which were contaminated with heavy metals, organic chemicals, and fecal coliform bacteria (FCB), were pumped into neighboring Lake Pontchartrain during dewatering. The impact of levee failure on water and benthic sediment concentrations in the lake was investigated by applying a numerical water quality model coupled to a three-dimensional, numerical hydrodynamic model. The model was used to compute water and benthic sediment concentrations throughout the lake for lead, arsenic, benzo(a)pyrene (BaP), and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE), and water concentrations for FCB. Computed concentrations resulting from actual pumped discharges with levee failure and overtopping were compared to computed concentrations resulting from pumped discharges without levee failure or overtopping, and concentrations from both sets of conditions were compared to ecological water and sediment quality screening guideline values. The model indicated that incremental increases above pre-Katrina benthic sediment concentrations are about a factor of 10 greater with dewatering of the floodwaters than with dewatering of storm water without flooding. However, these increases for the metals are small relative to pre-Katrina concentrations. The results showed that the ecological screening-level sediment quality guideline values were exceeded for BaP and DDE in areas near the south shoreline of the lake as a result of floodwater pump-out, whereas, this was not the case for storm water removal without flooding. The model showed that lake water column concentrations should be about the same during both dewatering conditions regardless of whether there is flooding or not.

  2. Bathymetric map, area/capacity table, and sediment volume estimate for Millwood Lake near Ashdown, Arkansas, 2013

    USGS Publications Warehouse

    Richards, Joseph M.; Green, W. Reed

    2013-01-01

    Millwood Lake, in southwestern Arkansas, was constructed and is operated by the U.S. Army Corps of Engineers (USACE) for flood-risk reduction, water supply, and recreation. The lake was completed in 1966 and it is likely that with time sedimentation has resulted in the reduction of storage capacity of the lake. The loss of storage capacity can cause less water to be available for water supply, and lessens the ability of the lake to mitigate flooding. Excessive sediment accumulation also can cause a reduction in aquatic habitat in some areas of the lake. Although many lakes operated by the USACE have periodic bathymetric and sediment surveys, none have been completed for Millwood Lake. In March 2013, the U.S. Geological Survey (USGS), in cooperation with the USACE, surveyed the bathymetry of Millwood Lake to prepare an updated bathymetric map and area/capacity table. The USGS also collected sediment thickness data in June 2013 to estimate the volume of sediment accumulated in the lake.

  3. Geochemical Responses to Anthropogenic and Natural Influences in Ebinur Lake Sediments of Arid Northwest China

    PubMed Central

    Wu, Jinglu; Abuduwaili, Jilili; Liu, Wen

    2016-01-01

    Geochemical concentrations were extracted for a short sediment core from Ebinur Lake, located in arid northwest China, and mathematical methods were used to demonstrate the complex pattern of the geochemical anomalies resulting from the temporal changes in natural and anthropogenic forces on the lake sediments. The first element assemblage (C1) (aluminum, potassium, iron, magnesium, beryllium, etc.) was predominantly terrigenous; among the assemblage, total phosphorus and titanium were generally consistent with aluminum except with regards to their surface sequences, which inferred the differences of source regions for terrigenous detrital material led to this change around ca. 2000AD. The second assemblage (C2) (calcium and strontium) was found to have a negative relationship with aluminum through a cluster analysis. The third assemblage (C3) included sodium and magnesium, which were influenced by the underwater lake environment and deposited in the Ebinur depression. The concentration ratio of C1/(C1+C2) was used as an indicator for denudation amount of detrital materials, which was supported by the values of magnetic susceptibility. The enrichment factors for heavy metals suggested that the influence of human activities on heavy-metal enrichment in Ebinur Lake region was not severe over the past century. Prior to the 1960s, geochemical indicators suggested a stable lacustrine environment with higher water levels. Beginning in the 1960s, high agricultural water demand resulted in rapid declines in lake water level, with subsequent increases of lake water salinity, as evidenced by enhanced sodium concentration in lake core sediments. During this period, anthropogenic activity also enhanced the intensity of weathering and the denudation of the Ebinur watershed. PMID:27176765

  4. Non-steady state diagenesis of organic and inorganic sulfur in lake sediments

    NASA Astrophysics Data System (ADS)

    Couture, Raoul-Marie; Fischer, Rachele; Van Cappellen, Philippe; Gobeil, Charles

    2016-12-01

    Sulfur controls the fate of many geochemical elements in lake sediments, including iron, phosphorus and environmentally important trace elements. We measured the speciation of pore-water and sediment-bound sulfur (aqueous sulfate and sulfides, elemental sulfur, iron monosulfide, pyrite, organic sulfur) and supporting geochemical variables (carbon, oxygen, iron) in the sediments of a perennially oxygenated and a seasonally anoxic basin of an oligotrophic lake in Québec, using a combination of pore-water analyses, sequential extractions and X-ray absorption near edge structure. A non-steady state early diagenetic model was developed and calibrated against this extensive dataset to help unravel the pathways and quantify the rates of S transformations. Results suggest that the main source of S to the sediments is the settling of organic ester-sulfate (R-O-SO3-H). Hydrolysis of these compounds provides an additional source of sulfate for anaerobic microbial oxidation of sedimentary organic matter, releasing sulfide to the pore-water. Reduced solid-bound S species accumulate as thiols (R-SH) and iron sulfides in the perennially oxygenated and seasonally anoxic basin, respectively. The model-estimated rate constant for R-SH formation is lower than previously estimated for this particular lacustrine site, but similar to that proposed for marine shelf sediments. The solid sediment S profiles, however, carry the imprint of the time-dependent sulfate input to the lake. Iron sulfide enrichments formed during past decades of elevated atmospheric SO4 deposition are presently dissolving. In the sediments of the perennially oxygenated basin this reaction hampers the build-up of Fe(III) (oxy)hydroxide near the sediment-water interface.

  5. Shifts in Identity and Activity of Methanotrophs in Arctic Lake Sediments in Response to Temperature Changes

    PubMed Central

    He, Ruo; Wooller, Matthew J.; Pohlman, John W.; Quensen, John; Tiedje, James M.

    2012-01-01

    Methane (CH4) flux to the atmosphere is mitigated via microbial CH4 oxidation in sediments and water. As arctic temperatures increase, understanding the effects of temperature on the activity and identity of methanotrophs in arctic lake sediments is important to predicting future CH4 emissions. We used DNA-based stable-isotope probing (SIP), quantitative PCR (Q-PCR), and pyrosequencing analyses to identify and characterize methanotrophic communities active at a range of temperatures (4°C, 10°C, and 21°C) in sediments (to a depth of 25 cm) sampled from Lake Qalluuraq on the North Slope of Alaska. CH4 oxidation activity was measured in microcosm incubations containing sediments at all temperatures, with the highest CH4 oxidation potential of 37.5 μmol g−1 day−1 in the uppermost (depth, 0 to 1 cm) sediment at 21°C after 2 to 5 days of incubation. Q-PCR of pmoA and of the 16S rRNA genes of type I and type II methanotrophs, and pyrosequencing of 16S rRNA genes in 13C-labeled DNA obtained by SIP demonstrated that the type I methanotrophs Methylobacter, Methylomonas, and Methylosoma dominated carbon acquisition from CH4 in the sediments. The identity and relative abundance of active methanotrophs differed with the incubation temperature. Methylotrophs were also abundant in the microbial community that derived carbon from CH4, especially in the deeper sediments (depth, 15 to 20 cm) at low temperatures (4°C and 10°C), and showed a good linear relationship (R = 0.82) with the relative abundances of methanotrophs in pyrosequencing reads. This study describes for the first time how methanotrophic communities in arctic lake sediments respond to temperature variations. PMID:22522690

  6. Streamflow, sediment transport, and nutrient transport at Incline Village, Lake Tahoe, Nevada, 1970-73

    USGS Publications Warehouse

    Glancy, Patrick A.

    1988-01-01

    Five principal creeks, First Creek, Second Creek, Wood Creek, Third Creek, and Incline Creek, having a cumulative drainage of 17.8 square miles, furnished a yearly average of about 15,000 acre-feet of runoff, mainly snowmelt, to Lake Tahoe during the 1970-73 water years. Annual runoff from the individual streams ranged from 460 to 7,070 acre-feet, and discharges ranged from 0.2 to 110 cubic feet per second. During the 4 years, the five streams delivered to Lake Tahoe 31,000 tons of sediment, which averaged about 75 percent gravel and sand, 15 percent silt, and 10 percent clay. Annual cumulative sediment load for the five creeks ranged from 1,500 to 11,000 tons; individual streams furnished 20 to 5,200 tons annually. Measured sediment transport at the stream mouths ranged from 1 to 13,200 milligrams per liter and from 0.001 to 1,420 tons per day; sediment concentrations up to 63,200 milligrams per liter were measured at upstream tributary sites. Estimated annual sediment yields of principal drainage basins ranged from 3 to 930 tons per square mile from undeveloped areas and from 26 to 5,000 tons per square mile from developed areas; yields for developed areas appeared to average about 10 times those of undeveloped areas, and roadways apparently were the major source. Erosion disequilibrium caused by prestudy flash floods on two of the creeks continues to manifest itself through high natural sediment yields. The Second Creek flood of 1967 yielded about 75,000 tons of sediment in one afternoon. Fluvial nutrient transport seems quantitatively related to magnitudes of sediment and water transport. Movement rates of organic nitrogen and particulate phosphorus were greater than rates of other nutrient species moving to the lake.

  7. Shifts in identity and activity of methanot