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Sample records for relict lake sediments

  1. Reconstructing paleo lake levels from relict shorelines along the Upper Great Lakes

    USGS Publications Warehouse

    Baedke, Steve J.; Thompson, Todd A.; Johnston, John W.; Wilcox, Douglas A.

    2004-01-01

    Shorelines of the upper Great Lakes include many embayments that contain strandplains of beach ridges. These former shoreline positions of the lakes can be used to determine changes in the elevation of the lakes through time, and they also provide information on the warping of the ground surface that is occurring in the Great Lakes after the weight of glacial ice was removed. Relative lake-level hydrographs can be created by coring the beach ridges to determine the elevation of basal foreshore (swash zone) deposits in each ridge and by obtaining radiocarbon dates of basal wetland sediments between ridges to generate an age model for the ridges. Because the relative-level hydrographs are the combination of lake-level change and vertical ground movement (isostatic rebound), the rebound must be removed to produce a graph that shows only the physical limits and timing of past lake-level fluctuations referenced to a common outlet. More than 500 vibracores of beach-ridge sediments were collected at five sites along Lake Michigan and four sites along Lake Superior. The cores showed a sequence of dune deposits overlying foreshore deposits that, in turn, overlie upper shoreface deposits. The base of the foreshore deposits is coarser and more poorly sorted than an overlying and underlying sediment and represents the plunge-point sediments at the base of the swash zone. The plunge-point deposits are a close approximation of the elevation of the lake when the beach ridge formed. More than 150 radiocarbon ages of basal wetland sediments were collected to produce age models for the sites. Currently, age models exist for all Lake Michigan sites and one Lake Superior site. By combining the elevation data with the age models, six relative lake-level hydrographs were created for the upper Great Lakes. An iterative approach was used to remove rebound from the five Lake Michigan relative hydrographs and merge the graphs into a single hydrograph. The resultant hydrograph shows long

  2. Discovery of relict subglacial lakes and their geometry and mechanism of drainage.

    PubMed

    Livingstone, Stephen J; Utting, Daniel J; Ruffell, Alastair; Clark, Chris D; Pawley, Steven; Atkinson, Nigel; Fowler, Andrew C

    2016-01-01

    Recent proxy measurements reveal that subglacial lakes beneath modern ice sheets periodically store and release large volumes of water, providing an important but poorly understood influence on contemporary ice dynamics and mass balance. This is because direct observations of how lake drainage initiates and proceeds are lacking. Here we present physical evidence of the mechanism and geometry of lake drainage from the discovery of relict subglacial lakes formed during the last glaciation in Canada. These palaeo-subglacial lakes comprised shallow (<10 m) lenses of water perched behind ridges orientated transverse to ice flow. We show that lakes periodically drained through channels incised into bed substrate (canals). Canals sometimes trend into eskers that represent the depositional imprint of the last high-magnitude lake outburst. The subglacial lakes and channels are preserved on top of glacial lineations, indicating long-term re-organization of the subglacial drainage system and coupling to ice flow. PMID:27292049

  3. Discovery of relict subglacial lakes and their geometry and mechanism of drainage

    PubMed Central

    Livingstone, Stephen J.; Utting, Daniel J.; Ruffell, Alastair; Clark, Chris D.; Pawley, Steven; Atkinson, Nigel; Fowler, Andrew C.

    2016-01-01

    Recent proxy measurements reveal that subglacial lakes beneath modern ice sheets periodically store and release large volumes of water, providing an important but poorly understood influence on contemporary ice dynamics and mass balance. This is because direct observations of how lake drainage initiates and proceeds are lacking. Here we present physical evidence of the mechanism and geometry of lake drainage from the discovery of relict subglacial lakes formed during the last glaciation in Canada. These palaeo-subglacial lakes comprised shallow (<10 m) lenses of water perched behind ridges orientated transverse to ice flow. We show that lakes periodically drained through channels incised into bed substrate (canals). Canals sometimes trend into eskers that represent the depositional imprint of the last high-magnitude lake outburst. The subglacial lakes and channels are preserved on top of glacial lineations, indicating long-term re-organization of the subglacial drainage system and coupling to ice flow. PMID:27292049

  4. GREAT LAKES CONTAMINATED SEDIMENTS PROGRAM

    EPA Science Inventory

    Contaminated sediments are a significant problem in the Great Lakes basin. Although discharges of toxic substances to the Great Lakes have been reduced in the last 20 years, persistent high concentrations of contaminants in the bottom sediments of rivers and harbors have raised...

  5. 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.

  6. 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

  7. Recent increases in the large glacial-relict calanoid Limnocalanus macrurus in Lake Michigan

    USGS Publications Warehouse

    Barbiero, R.P.; Bunnell, D.B.; Rockwell, D.C.; Tuchman, M.L.

    2009-01-01

    Since 2004, population density of the large hypolimnetic calanoid Limnocalanus macrurus Sars. has increased dramatically in Lake Michigan. The average summer biomass of this species between 2004 and 2006 was roughly three times that of the period 1984–2003, and at levels unprecedented in our 22-year dataset, making L. macrurus the dominant zooplankter in the lake in terms of biomass. These increases have been accentuated by coincident population declines of the main daphnid, Daphnia mendotae, in the lake with the result that in 2006, L. macrurus accounted for 75% and 50% of the large (> 0.9 mm) crustacean biomass in the northern and southern basins of Lake Michigan, respectively. The increases in L. macrurus populations have closely coincided with equally dramatic increases in summer water clarity. Recent extinction coefficients are among the lowest recorded for the lake, and deepening light penetration has permitted increases in the size of the deep chlorophyll layer. In addition, planktivorous fish populations have declined coincidently with the increases in L. macrurus. It seems likely that an increase in sub-epilimnetic production has resulted in increased food resources for the deep-living L. macrurus, while low planktivore abundances have reduced predation loss, permitting L. macrurus to respond to these increases in sub-epilimnetic production.

  8. Holocene sediments within lake catchments - testing sediment delivery

    NASA Astrophysics Data System (ADS)

    Dreibrodt, S.; Bork, H.-R.

    2009-04-01

    Results of detailed investigation of soils, colluvia and lake sediments in a lake catchment in northern Germany proves that the input of eroded soil (enabled by agricultural land use) is of a minor amount compared with the storage within colluvial layers. Pre-existing micro- and meso-topography and prehistorical land use patterns as well as precipitation intensity are probable to control the Holocene flux of sediments within the lake catchment area. Therefore we entertain some doubt if sediment delivery ratios- usually applied on larger spatial scales (e. g. river catchment areas)- are useful to produce reliable quantitative data of Holocene soil erosion in central Europe.

  9. 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...

  10. 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

  11. New insights on water level variability for Lake Turkana for the past 15 ka and at 150 ka from relict beaches

    NASA Astrophysics Data System (ADS)

    Forman, S. L.; Wright, D.

    2015-12-01

    Relict beaches adjacent to Lake Turkana provide a record of water level variability for the Late Quaternary. This study focused on deciphering the geomorphology, sedimentology, stratigraphy and 14C chronology of strand plain sequences in the Kalokol and Lothagam areas. Nine >30 m oscillations in water level were documented between ca. 15 and 4 ka. The earliest oscillation between ca. 14.5 and 13 ka is not well constrained with water level to at least 70 m above the present surface and subsequently fell to at least 50 m. Lake level increased to ~ 90 m between ca. 11.2 and 10.4 ka, post Younger Dryas cooling. Water level fell by >30 m by 10.2 ka, with another potential rise at ca. 8.5 ka to >70 m above current level. Lake level regressed by > 40 m at 8.2 ka coincident with cooling in the equatorial Eastern Atlantic Ocean. Two major >70 m lake level oscillations centered at 6.6 and 5.2 ka may reflect enhanced convection with warmer sea surface temperatures in the Western Indian Ocean. The end of the African Humid Period occurred from ca. 8.0 to 4.5 ka and was characterized by variable lake level (± > 40 m), rather than one monotonic fall in water level. This lake level variability reflects a complex response to variations in the extent and intensity of the East and West African Monsoons near geographic and topographic limits within the catchment of Lake Turkana. Also, for this closed lake basin excess and deficits in water input are amplified with a cascading lake effect in the East Rift Valley and through the Chew Bahir Basin. The final regression from a high stand of > 90 m began at. 5.2 ka and water level was below 20 m by 4.5 ka; and for the remainder of the Holocene. This sustained low stand is associated with weakening of the West African Monsoon, a shift of the mean position of Congo Air Boundary west of the Lake Turkana catchment and with meter-scale variability in lake level linked to Walker circulation across the Indian Ocean. A surprising observation is

  12. 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. PMID:19091379

  13. 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

  14. Stable carbon and oxygen isotope record of central Lake Erie sediments

    USGS Publications Warehouse

    Tevesz, M.J.S.; Spongberg, A.L.; Fuller, J.A.

    1998-01-01

    Stable carbon and oxygen isotope data from mollusc aragonite extracted from sediment cores provide new information on the origin and history of sedimentation in the southwestern area of the central basin of Lake Erie. Sediments infilling the Sandusky subbasin consist of three lithologic units overlying glacial deposits. The lowest of these is a soft gray mud overlain by a shell hash layer containing Sphaerium striatinum fragments. A fluid mud unit caps the shell hash layer and extends upwards to the sediment-water interface. New stable isotope data suggest that the soft gray mud unit is of postglacial, rather than proglacial, origin. These data also suggest that the shell hash layer was derived from erosional winnowing of the underlying soft gray mud layer. This winnowing event may have occurred as a result of the Nipissing flood. The Pelee-Lorain moraine, which forms the eastern boundary of the Sandusky subbasin, is an elevated area of till capped by a sand deposit that originated as a beach. The presence of both the shell hash layer and relict beach deposit strengthens the interpretation that the Nipissing flood was a critical event in the development of the southwestern area of the central basin of Lake Erie. This event, which returned drainage from the upper lakes to the Lake Erie basin, was a dominant influence on regional stratigraphy, bathymetry, and depositional setting.

  15. 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.

  16. Urban lake sediment chemistry: Lake design, runoff, and watershed impact

    SciTech Connect

    Amalfi, F.A.

    1988-01-01

    Sediments of twenty-two urban lakes and stormwater discharge into five of the impoundments were analyzed for the presence of selected metallic priority pollutants, total petroleum hydrocarbons, and volatile and extractable organic compounds. The concentration (mg/kg dry weight) ranges of metals in lake sediments were: arsenic 7-29, cadmium < 0.5-0.5, chromium 14-55, lead <1-138, selenium <0.01-1.1, silver 0.2-2.1, copper 25-2760, nickel 5-40, and zinc 33.9-239. Concentrations of total petroleum hydrocarbons ranged from 30 to 4400 mg/kg (wet weight). Organic priority pollutants detected in the urban lake impoundments included tetrachlorethylene, 1,1,2-trichloroethane, trichlorofluoromethane, phthalate esters, chloroform, and dichlorobromomethane. Stormwater runoff contained measurable quantities of arsenic, chromium, lead, selenium, copper, nickel, zinc, and petroleum hydrocarbons; whereas organic priority pollutants were not detected. Stormwater runoff pollutant loads indicated that runoff provides a significant contribution of metals and petroleum hydrocarbons to lake sediments.

  17. Relationship Between Holocene Sediment Accumulation and Lake-Volume Change in a Small Coastal Lake in Southwestern Australia

    NASA Astrophysics Data System (ADS)

    Telles, F.; Pedone, V.; George, A.

    2004-12-01

    Change in lithology in a 180-cm-long lake-center core from Lake Thetis, Western Australia serves as a proxy for change in lake volume during the Holocene. Lake Thetis is located on the coastal plain 245 km north of Perth, 1.25 km inland from the Indian Ocean. It occupies a sinkhole in middle Holocene limestone. The 300-m-diameter, steep-sided, ~2-m-deep lake has a 5-m-wide marginal terrace covered by relict and living stromatolites and a bottom covered by a thick, red-purple microbial mat. Lake elevation is not monitored, but changes noted over a 25-year period of up to 0.5 m have alternately exposed and submerged the stromatolite terrace. No hydrological study has been done to determine if the lake has a subterranean connection to the sea. Limited measurements of salinity and pH are similar to or greater than those of seawater. The laminated sediment from the core is divided into three intervals based on texture. From 0 to 45 cm, the core consists of uncompacted, red-purple, organic-rich muddy sand. Very fine-grained carbonate sand forms 50% of the sediment. This interval also contains five, lighter-colored bands, where carbonate sand forms up to 90% of the sediment. From 45 to 130 cm, the core consists of laminated red-brown, muddy, very fine sand and light-red-brown, slightly muddy medium- to fine-grained sand. The frequency of medium- to fine-grained sand layers decreases, but the layer thickness increases, upward. Carbonate grains in the thickest layers are coated with iron-oxide minerals. From 130 to 180 cm, the core consists of alternating red-brown mud, light-gray-purple mud, sandy mud, and muddy very fine sand. The carbonate sand is mostly derived from erosion of the stromatolite terrace, with minor eolian contribution from coastal-plain dunes. Therefore, the mud-dominated basal unit accumulated during a time of high lake elevation, when stromatolites were submerged and actively forming. The middle sand-dominated interval accumulated during a time of low

  18. VERTICAL MIXING OF LAKE SEDIMENTS BY TUBIFICID OLIGOCHAETES

    EPA Science Inventory

    Vertical mixing of lake sediments by tubificid oligochaetes was studied in laboratory experiments by using a radioactive (cesium 137 labeled sediment) marker horizon. Results from these experiments were used to develop and test a mathematical model describing tubificid sediment m...

  19. Lake-floor sediment texture and composition of a hydrothermally-active, volcanic lake, Lake Rotomahana

    NASA Astrophysics Data System (ADS)

    Pittari, A.; Muir, S. L.; Hendy, C. H.

    2016-03-01

    Young volcanic lakes undergo a transition from rapid, post-eruptive accumulation of volcaniclastic sediment to slower pelagic settling under stable lake conditions, and may also be influenced by sublacustrine hydrothermal systems. Lake Rotomahana is a young (129 year-old), hydrothermally-active, volcanic lake formed after the 1886 Tarawera eruption, and provides a unique insight into the early evolution of volcanic lake systems. Lake-bottom sediment cores, 20-46 cm in length, were taken along a transect across the lake and characterised with respect to stratigraphy, facies characteristics (i.e., grain size, componentry) and pore water silica concentrations. The sediments generally comprise two widespread facies: (i) a lower facies of light grey to grey, very fine lacustrine silt derived from the unconsolidated pyroclastic deposits that mantled the catchment area immediately after the eruption, which were rapidly reworked and redeposited into the lake basin; and (ii) an upper facies of dark, fine-sandy diatomaceous silt, that settled from the pelagic zone of the physically stable lake. Adjacent to sublacustrine hydrothermal vents, the upper dark facies is absent, and the upper part of the light grey to grey silt is replaced by a third localised facies comprised of hydrothermally altered pale yellow to yellowish brown, laminated silt with surface iron-rich encrustations. Microspheres, which are thought to be composed of amorphous silica, although some may be halloysite, have precipitated from pore water onto sediment grains, and are associated with a decrease in pore water silicon concentration. Lake Rotomahana is an example of a recently-stabilised volcanic lake, with respect to sedimentation, that shows signs of early sediment silicification in the presence of hydrothermal activity.

  20. 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.

  1. 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.

  2. Dynamics of suspended sediment in Lake Ontario

    NASA Technical Reports Server (NTRS)

    Pluhowski, E. J. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. The suspended sediment plumes generated by the Welland Canal and the Genesee River are identifiable in most band 5 frames received from ERTS-1. In descending order of value for plume detection in Lake Ontario are bands 4, 6, and 7. Little or no information content relative to plume detection is available in band 7. The Oswego River plume was not visible during low flow periods; however, it was identifiable immediately following storms. Increased suspended sediment loading emanating from storm runoff increases turbidity levels to the point where the plume becomes visible in the ERTS-1 imagery. Despite the fact that it is detectable from high altitude (60,000 feet) photography, the Niagara River plume was not visible in any of the ERTS-1 frames. Numerous examples of shoreline erosion were evident in the December 7, 1972, imagery of western Lake Ontario. Near shore lake circulation patterns are usually apparent whenever turbidity plumes are sensed by the satellite.

  3. [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. PMID:15162731

  4. 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. PMID:27104923

  5. 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...

  6. Practical Implications of Quantifying Ancient Sedimentation Rates in Lakes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sediments stored in lakes represent a valuable archive that can be used to reveal the erosion history of watersheds. A portion of the soil that is moved down gradient during runoff events is deposited in lakes, and the rate at which sediment accumulates should be proportional to the rate of erosion...

  7. MODELLING SEDIMENT TRANSPORT FOR THE LAKE MICHIGAN MASS BALANCE PROJECT

    EPA Science Inventory

    A sediment transport model is one component of the overall ensemble of models being developed for the Lake Michigan Mass Balance. The SEDZL model is being applied to simulate the fine-grained sediment transport in Lake Michigan for the 1982-1983 and 1994-1995 periods. Model perf...

  8. Genetic differences among several species of Tricladida from the relict Lake Ohrid as revealed by enzyme electrophoresis.

    PubMed

    Sywula, Tadeusz; Krstanovski, Zdravko; Tasevska, Orhideja; Sell, Jerzy; Kretowicz, Tomasz

    2003-01-01

    Six endemic and two widely distributed species living in Lake Ohrid were studied. In general, these hermaphroditic animals displayed no signs of departure from Hardy-Weinberg equilibrium. Genetic variation in all but one of the endemic species was of the same extent as that in geographically wide ranging invertebrates. On the other hand, the Lake Ohrid population of the common European species Dendrocoelum lacteum was monomorphic at all loci examined. D. sanctinaumi, one of the endemic species, exhibited a clear genetic subdivision into spring and littoral subpopulations. The genetic differentiation of Crenobia alpina alpina and C. a. montenigrina proved commensurable to that of well separated species from other genera. The data suggest that the separation of particular lineages in the set of Lake Ohrid endemics was widely dispersed over time. PMID:14686654

  9. Mineralization of allochthonous organic carbon in lake sediments, from lake to landscape scale

    NASA Astrophysics Data System (ADS)

    Gudasz, C.; Ask, J.; Tranvik, L. J.; Karlsson, J.

    2012-04-01

    Lake sediments are well-recognized sites for the processing as well as sequestration of organic carbon. In particular boreal lake sediments have been recognized as important sites for the sequestration of organic carbon, comparable to soils or living biomass. Lakes in the boreal zone import large amounts of terrestrially derived organic carbon. Part of this organic carbon reaches the sediment surface through flocculation and sedimentation. The microbial processing of organic carbon represents one of the main factors that regulate the balance between sequestration of organic carbon and emission of green house gasses in boreal lake sediments. Recently, it has been shown a strong constrained microbial processing of allochthonous organic carbon in boreal lake sediments. However, a clear picture about the extent of the allochthonous organic carbon influence on the mineralization of sediment organic carbon in lakes and its significance at a large scale is currently lacking. We conducted a study, which explored the effect of allochthonous organic carbon on sediment organic carbon mineralization along a gradient of lakes characterized by increasing terrestrial organic carbon influence. We show a strong negative effect on sediment mineralization in lakes with increasing allochthonous organic carbon influence, which applies to a large number of lakes in the boreal zone.

  10. REVIEW OF HISTORICAL AND RECENT MERCURY CONCENTRATIONS IN GREAT LAKES SEDIMENTS

    EPA Science Inventory

    Sediments of the Great Lakes have been impacted by inputs of mercury to the lakes. The first measurements of mercury concentrations in Great Lakes sediments were for samples collected in 1968 for Lake Ontario, 1969 for Lake Huron, 1969-70 for Lake Michigan, 1970 for Lake St. Cl...

  11. The impact of proglacial lakes on downstream sediment delivery

    NASA Astrophysics Data System (ADS)

    Bogen, Jim; Xu, Mengzhen; Kennie, Patricia

    2013-04-01

    This paper discusses the impact of proglacial lakes on sediment transport of three different glaciers: Nigardsbre, Engabre and Tunsbergdalsbre. All of these lakes were developed in modern time. The recession of the Nigardsbre uncovered a 1.8 km long and on average 15 m deep proglacial lake during the years 1937 to 1968. From that time the glacier front was situated entirely on land, and the sediment input and output to the lake were measured. Sediment samples were collected 2- 4 times a day and the water discharge was recorded. The sediment transport into and out of the lake was on average 10504 t yr-1 and 2340 t yr-1during the years 1968 - 1981. Thus, 23% remained in suspension at the outlet. In 2011 an excessively high transport of 32356 t yr-1was recorded, due to several large flash floods that year. A 1.9 km long and up to 90 m deep proglacial lake downstream from Engabre glacier was uncovered during the years 1930 - 1945. The average suspended sediment load delivered from the glacier during the years 1970 - 1981 amounted to 12375 t yr-1and the transport out of the lake was 2021 t yr-1, giving an average of 16% remaining in suspension. In 2000 the sediment transport into the lake amounted to 15450 t yr-1. For the Tunsbergdalsbre glacier, measurements in the early 1970s indicated that the suspended sediment transport was on average 44000 t yr-1. From 1987 to 1993 the recession of the glacier uncovered a proglacial lake. Downstream from this 0.3 km long and around 9 m deep lake, the suspended sediment load was measured as 28 000 t yr-1in 2009, indicating that as much as 64% remained in suspension. The various factors affecting the sedimentation rates in the proglacial lakes are discussed. The low sedimentation rate of the lake in front of the Tunsbergdalsbre was due to its limited length and depth. Hence the meltwater from the glacier maintains a high flow velocity. The lake will however increase its size as the glacier recedes. The two other lakes have gone

  12. Paleomagnetism of Lake Sediments, Chew Bahir, Ethiopia

    NASA Astrophysics Data System (ADS)

    Frank, U.; Brown, M. C.; Foerster, V. E.; Schäbitz, F.

    2011-12-01

    Quasi-continuous variations of the Earth's magnetic field recorded in lake sediments can provide detailed time series describing the evolution of the geomagnetic field. To make robust conclusions about underlying geodynamo processes an improvement in the global coverage of recording sites is required. Current lake data for the late Brunhes are biased towards Europe and North America with only five studies reporting paleomagnetic results from equatorial Africa. We present inclination and relative paleointensity from Chew Bahir, southern Ethiopia; a saline mudflat located in the East African Ridge System, previously covered by a ~2000 km2 lake. Discrete measurements were made on two ten meter cores, which we continuously sub-sampled at 2 cm intervals. Calibrated AMS radiocarbon ages constrain the base of the cores to ~45 ka. NRM was demagnetized in ten steps up to 100 mT and well defined characteristic remanence directions, with MAD < 3°, were determined for the majority of specimens. Secondary components of magnetization were generally removed after alternating field demagnetization to 15 mT. Inclination is compared with previously obtained directional records from Lake Turkana, northern Kenya (~60 km to the southwest of Chew Bahir), and we discuss differences between these records. The ratio of NRM to ARM intensity at 20 mT was used as a proxy for relative paleointensity. Broad similarities in variations in relative paleointensity are seen between Chew Bahir and other globally distributed sites; most evidently through the Holocene. The magnetic mineralogy of the cores has been determined using a number of rock magnetic methods and has been used to assess the fidelity of the paleomagnetic records.

  13. 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.

  14. 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

  15. COVERING BOTTOM SEDIMENTS AS A LAKE RESTORATION TECHNIQUE

    EPA Science Inventory

    Sediment covering to control macrophytes and sediment nutrient release is reviewed. It is concluded that fly ash application to control sediment phosphorus release presents more dangers to the lake than benefits and should not be used. Polyethylene sheeting has not had long term ...

  16. Sedimentation in Lake Tuscaloosa, Alabama, 1982-86

    USGS Publications Warehouse

    Slack, L.J.; Pritchett, J.L.

    1988-01-01

    Lake Tuscaloosa, created in 1969 by the impoundment of North River, provides the primary water supply for Tuscaloosa, Alabama , and surrounding areas. This report describes the rate of sedimentation in the lake from its principal tributaries. The rate of sediment deposition in the lake is low. The maximum sediment deposition from 1982 to 1986 at 17 lake cross sections was about 3.5 feet (or 0.9 foot per year) at a cross section that received drainage from Brush Creek basin. Brush Creek is an unmined basin with steep overland and channel slopes. At 15 of the 17 cross sections, the maximum sediment deposition was less than 2 feet (or 0.5 foot per year). Scour and fill processes (redistribution of the sediment) appear to be taking place at many of the cross sections. (Author 's abstract)

  17. Geochemistry of Lake Van pore water and sediment, or How to distinguish climatic from diagenetic signals?

    NASA Astrophysics Data System (ADS)

    Kwiecien, Ola; Tomonaga, Yama; Brennwald, Matthias S.; Randlett, Marie-Eve; Peterse, Francien; Bechtel, Achim; van der Meer, Marcel; Stockhecke, Mona; Bucher, Stefan; Anselmetti, Flavio; Litt, Thomas; Schubert, Carsten J.; Kipfer, Rolf

    2014-05-01

    Lake Van is a terminal soda lake located in a semiarid region (eastern Anatolia, Turkey). Its geographical setting makes Lake Van a superb archive of paleoenvironmental changes. One of the aims of the ICDP PALEOVAN project is the reconstruction of the hydrological and climatic variability in the eastern Mediterranean region and the Near East on glacial/interglacial and millennial time scales. We applied a multi-proxy approach to distinguish the environmental synsedimentary imprint and the postsedimentary diagenetic changes. Microfaunal evidence, carbonate isotopic composition (d18O, d13C), molecular proxies (BIT, ACE) and isotopic composition of lipid biomarkers (dD) are matched with isotopic and elemental composition (d18O, dD, Mg, Ca, Sr, Cl, salinity) of sediment pore-water. An excellent correspondence between these proxies indicates that the elemental composition of pore water in Lake Van does not result from diagenetic changes, but, unlike in many cases known from marine environment, represents to some extent relicts of 'paleolake-water'. On the contrary, the stable isotopic composition of the pore water (d18O, dD) seems to reflect more recent hydrological regime dominated by precipitation/evaporation changes. As salinity and chlorine concentration changes mimic the isotopic composition of biomarkers for the last 140 ka, we use pore-water data to quantify changes in the lake level. Our reconstruction (Tomonaga et al., in review) is in line with previous studies on lake terraces (Kuzucuoglu et al., 2010) and seismic surveys (Cukur et al., 2012) showing a major transgression of up to 105 m with respect to the current lake level during the last interglacial (MIS5e), and a major regression of ~145 m at ~30 ka BP during the last glacial. Kuzucuoglu et al. (2010) Formation of the Upper Pleistocene terraces of Lake Van (Turkey). Journal of Quaternary Science 25, 1124-1137. Cukur et al. (2012) Sedimentary evolution of Lake Van (Eastern Turkey) reconstructed from high

  18. Enrichment of metals in the surface sediments of Sapanca Lake

    SciTech Connect

    Bakan, G.; Balkas, T.I.

    1999-01-01

    A comprehensive lake sediment study was performed on the Sapanca Lake of Turkey in which certain metal analyses were conducted using inductively coupled plasma atomic emission spectroscopy. The purpose of the study was to find the enrichment of metals in the surface sediments of Sapanca Lake. A method, namely, the index of geoaccumulation, was used to define the degree of anthropogenic pollution in the Sapanca Lake basin. Results of the geoaccumulation index indicate that only enrichments of trace metals, cadmium, and lead are found.

  19. 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

  20. /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.

  1. Isotopic fingerprints of anthropogenic molybdenum in lake sediments.

    PubMed

    Chappaz, Anthony; Lyons, Timothy W; Gordon, Gwyneth W; Anbar, Ariel D

    2012-10-16

    We measured the molybdenum isotope compositions (δ(98)Mo) of well-dated sediment cores from two lakes in eastern Canada in an effort to distinguish between natural and anthropogenic contributions to these freshwater aquatic systems. Previously, Chappaz et al. (1) ascribed pronounced 20th-century Mo concentration enrichments in these lakes to anthropogenic inputs. δ(98)Mo values in the deeper sediments (reflecting predominantly natural Mo sources) differ dramatically between the two lakes: -0.32 ± 0.17‰ for oxic Lake Tantare and +0.64 ± 0.09‰ for anoxic Lake Vose. Sediment layers previously identified as enriched in anthropogenic Mo, however, reveal significant δ(98)Mo shifts of ± 0.3‰, resulting in isotopically heavier values of +0.05 ± 0.18‰ in Lake Tantare and lighter values of +0.31 ± 0.03‰ in Lake Vose. We argue that anthropogenic Mo modifies the isotopic composition of the recent sediments, and we determine δ(98)Mo(anthropogenic) values of 0.1 ± 0.1‰ (Lake Vose) and 0.2 ± 0.2‰ (Lake Tantare). These calculated inputs are consistent with the δ(98)Mo of molybdenite (MoS(2)) likely delivered to the lakes via smelting of porphyry copper deposits (Lake Vose) or through combustion of coal and oil also containing Mo (Lake Tantare). Our results confirm the utility of Mo isotopes as a promising fingerprint of human impacts and perhaps the specific sources of contamination. Importantly, the magnitudes of the anthropogenic inputs are large enough, relative to the natural Mo cycles in each lake, to have an impact on the microbiological communities. PMID:22970917

  2. 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

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

    PubMed

    Baranov, Viktor; Lewandowski, Jörg; Krause, Stefan

    2016-08-01

    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 m(2) 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

  4. 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 ...

  5. Cesium-137 and mercury contamination in lake sediments.

    PubMed

    Matsunaga, T; Ueno, T; Chandradjith, R L; Amano, H; Okumura, M; Hashitani, H

    1999-07-01

    The contribution of fluvial discharge and global fallout of 137Cs and mercury to sedimentation fluxes in Lake Shinji and Lake Nakaumi, Japan, was studied. The fluvial flux through soil erosion accounted for 11 to 27% of accumulated 137Cs in the sediments in the 1950's and 1960's, which were the periods of the most extensive atmospheric input, and for 90 to 100% in the 1990's. The vertical profiles of mercury concentrations in the lake sediments studied showed a maximum between 1959 and 1963, which was originated mostly from the extensive use of mercury-agrochemicals in paddyfields of the watershed in the past. These findings are representative examples of long-term contamination of lake sediments caused by the contaminated ground soil erosion. PMID:10399844

  6. Polycyclic aromatic hydrocarbons in lake sediments from the High Tatras.

    PubMed

    van Drooge, Barend L; López, Jordi; Fernández, Pilar; Grimalt, Joan O; Stuchlík, Evzen

    2011-05-01

    European alpine lake systems are used as indicators of air quality over the continent. Preliminary data showed high polycyclic aromatic hydrocarbons (PAH) loads in the High Tatras (Eastern Europe) in comparison to other mountain regions. Here, insight on the spatial distribution of PAH is provided from analysis of top-core sediments of 27 alpine lakes distributed along the High Tatras. Top-core sediment concentrations were higher than those in deep-cores, and they were higher than those observed in other European high mountain regions. The PAH profiles were uniform and comparable to those observed in aerosols and snow, indicating that atmospheric deposition was the predominant PAH input pathway to the lakes. Good agreement between estimated atmospheric deposition and sedimentation fluxes was observed. However, in several lakes in the western range higher sediment fluxes may correspond to higher PAH depositions levels. The higher concentrations may also reflect inputs from potential emission source areas. PMID:21353356

  7. 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

  8. Purines and pyrimidines in sediments from lake erie.

    PubMed

    Van Der Velden, W; Schwartz, A W

    1974-08-23

    Quantitative analyses of purines and pyrimidines in sequential sections of cores from the central and eastern basins of Lake Erie show steeply increasing concentrations in the youngest sediments. This may be related to increased loading of nutrients and recent cultural eutrophication of the lake. The purine and pyrimidine distributions suggest the operation of a specific degradative process for uracil at an extremely early stage in, or prior to, sediment formation. PMID:17736373

  9. Seasonal variations in pore water and sediment geochemistry of littoral lake sediments (Asylum Lake, MI, USA)

    PubMed Central

    Koretsky, Carla M; Haas, Johnson R; Miller, Douglas; Ndenga, Noah T

    2006-01-01

    Background Seasonal changes in pore water and sediment redox geochemistry have been observed in many near-surface sediments. Such changes have the potential to strongly influence trace metal distribution and thus create seasonal fluctuations in metal mobility and bioavailability. Results Seasonal trends in pore water and sediment geochemistry are assessed in the upper 50 cm of littoral kettle lake sediments. Pore waters are always redox stratified, with the least compressed redox stratification observed during fall and the most compressed redox stratification observed during summer. A 2-step sequential sediment extraction yields much more Fe in the first step, targeted at amorphous Fe(III) (hydr)oxides (AEF), then in the second step, which targets Fe(II) monosulfides. Fe extracted in the second step is relatively invariant with depth or season. In contrast, AEF decreases with sediment depth, and is seasonally variable, in agreement with changes in redox stratification inferred from pore water profiles. A 5-step Tessier extraction scheme was used to assess metal association with operationally-defined exchangeable, carbonate, iron and manganese oxide (FMO), organic/sulfide and microwave-digestible residual fractions in cores collected during winter and spring. Distribution of metals in these two seasons is similar. Co, As, Cd, and U concentrations approach detection limits. Fe, Cu and Pb are mostly associated with the organics/sulfides fraction. Cr and Zn are mostly associated with FMO. Mn is primarily associated with carbonates, and Co is nearly equally distributed between the FMO and organics/sulfide fractions. Conclusion This study clearly demonstrates that near-surface lake sediment pore water redox stratification and associated solid phase geochemistry vary significantly with season. This has important ramifications for seasonal changes in the bioavailability and mobility of trace elements. Without rate measurements, it is not possible to quantify the

  10. 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...

  11. ARSENIC SEDIMENTATION ALONG THE SLOPE OF A LAKE BASIN

    EPA Science Inventory

    Lake Lansing, Michigan was treated with sodium arsenite for macrophyte control in 1957. even 1.5-m sediment cores were taken along a line through the littoral zone to the deepest portion of the lake and analyzed for arsenic. n each core, arsenic concentrations going from the surf...

  12. Holocene Tephrochronology from Lake Sediments, Redoubt Volcano, Alaska

    NASA Astrophysics Data System (ADS)

    Schiff, C. J.; Kaufman, D. S.; Wallace, K. L.

    2006-12-01

    Lake sediments in volcanically active areas provide a geological archive of tephra-fall events because sedimentation often occurs continuously and organic material for 14C dating is commonly available; lake sediments, therefore, contain valuable information about tephra fall and associated hazards. Recovering tephra-fall records from lakes requires careful site selection, core recovery, and tephra age assignments. 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 ca. 8750 cal yr BP. A previous core taken from a shallow site at Bear Lake contains 38 tephra layers suggesting that a deeper site in lakes provides a more complete sediment record as shallow sites are susceptible to remobilization and have lower sedimentation rates. We use 12 AMS 14C ages, along with the 137Cs and 210Pb activities of the top 8.5 cm of sediment, to evaluate different models to determine the age-depth relation of sediment, and to determine the age of each tephra deposit. The selected age model is based on a cubic smooth spline function that was passed through the adjusted tephra-free depth of each dated layer; the age model provides an example of how best to date lake sediment in a volcanically active area where presumably instantaneous tephra deposition compounds a simple age-depth relationship. Using the age model we find that 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 ca. 2500-3500, 4500-5000, and 7000-7500 cal yr BP. Our record suggests that Bear Lake experienced extended periods (1000-2000 yr) of increased tephra fall between shorter periods (500-1000 yr) of quiescence. The Bear Lake sediment core affords the most comprehensive tephrochronology from the base of the Redoubt Volcano to date, with an average

  13. Evaluation of micro-organic pollution in lake sediments: application to Akanoi Bay, Lake Biwa, Japan.

    PubMed

    Shimzu, Y; Matsui, S; Harada, J

    2003-07-01

    The pollution of lake sediments by organic micro-pollutants has been of growing environmental concern due to their suspected long-term effects on both human health and the surrounding ecosystem. In this research, in order to investigate and evaluate the micro-organic pollution in lake sediments, an analytical methodology consisting of freeze-drying, Soxhlet extraction with dichloromethane, concentration by rotary-evaporator, purification and fractionation by Sep-pak florigil cartridge, and quantification by GC/MS was formulated and applied to the lake sediments of Akanoi Bay, Lake Biwa in Japan. Two polycyclic aromatic hydrocarbons (PAHs) (i.e., fluoranthene and pyrene) were detected in the collected sediment samples. Based on the horizontal distribution of these two PAHs and the particle size distribution of the sediment samples, it was considered that the river inflows (the land usage in their upstream is mainly paddy field andresidential) into the bay are the major pollution sources. PMID:12916840

  14. Identification of bacterial communities in sediments of Poyang Lake, the largest freshwater lake in China.

    PubMed

    Kou, Wenbo; Zhang, Jie; Lu, Xinxin; Ma, Yantian; Mou, Xiaozhen; Wu, Lan

    2016-01-01

    Bacteria play a vital role in various biogeochemical processes in lacustrine sediment ecosystems. This study is among the first to investigate the spatial distribution patterns of bacterial community composition in the sediments of Poyang Lake, the largest freshwater lake of China. Sediment samples were collected from the main basins and mouths of major rivers that discharge into the Poyang Lake in May 2011. Quantitative PCR assay and pyrosequencing analysis of 16S rRNA genes showed that the bacteria community abundance and compositions of Poyang Lake sediment varied largely among sampling sites. A total of 25 phyla and 68 bacterial orders were distinguished. Burkholderiales, Gallionellales (Beta-proteobacteria), Myxococcales, Desulfuromonadales (Delta-proteobacteria), Sphingobacteriales (Bacteroidetes), Nitrospirales (Nitrospirae), Xanthomonadales (Gamma-proteobacteria) were identified as the major taxa and collectively accounted for over half of annotated sequences. Moreover, correlation analyses suggested that higher loads of total phosphorus and heavy metals (copper, zinc and cadmium) could enhance bacterial abundance in the sediment. PMID:27047727

  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. AGGREGATION AND DISAGGREGATION OF FINE-GRAINED LAKE SEDIMENTS

    EPA Science Inventory

    The effects of fluid shear and sedimentation concentration on the aggregation, and especially disaggregation, of fine-grained sediments in lake waters continues to be an important research area. It has been shown in previous studies that the steady-state median floc size decrease...

  17. 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 ...

  18. 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...

  19. EARLY DIAGENESIS AND CHEMICAL MASS TRANSFER IN LAKE ERIE SEDIMENTS

    EPA Science Inventory

    Vertical profiles of pore water and sediment solids chemistry were obtained from two sites in Lake Erie. Samples were collected using both gravity coring and pore water 'peeper' techniques. In general, concentrations of nutrients and toxic metals in sediment solids decreased with...

  20. Sediment Transport and Water Quality Model of Cedar Lake, Indiana

    NASA Astrophysics Data System (ADS)

    James, S. C.; Jones, C. A.; Roberts, J. D.; Ahlmann, M.; Bucaro, D. A.

    2006-12-01

    The EPA-supported Environmental Fluid Dynamics Code, EFDC, is used to model hydrodynamics, sediment transport, and water quality in coastal regions, estuaries, rivers, and lakes. However, the empirical formulations used for sediment transport are not always adequate to accurately characterize cohesive sediment erosion and transport. New sediment transport subroutines have been incorporated into EFDC and the new model is called SNL-EFDC. The updated model provides an improved, coupled hydrodynamics, sediment transport, and water quality framework. The newly incorporated sediment transport subroutines facilitate direct use of measured erosion rate data from the Sediment Erosion with Depth Flume (SEDflume). Erosion rates are included as functions of both depth within the sediment bed and applied shear stresses. This bypasses problems associated with empirical erosion formulations often based on disaggregated particle size. Restoration alternatives are under consideration for Cedar Lake in Indiana and SNL-EFDC models its hydrodynamics, sediment transport, and water quality. The water quality model as implemented on Cedar Lake tracks algae, oxygen, temperature, carbon, phosphorous, and nitrogen kinetics, as well as, sediment bed diagenesis. Environmental conditions, wind, temperature, rainfall, and sunlight, were based on data collected in 2005. Tributary loading was modeled using L-THIA and provided influxes of water, nutrients (phosphorous, nitrogen, etc.), and sediments. The calibrated model was used to simulate a nine month period from March to November 2005. Results suggest that the model simulates sediments transport and associated water quality correctly. The calibrated model is being used to evaluate several restoration measures throughout the lake and watershed and their effect on water quality. Because Cedar Lake is a nitrogen limited lake, changes in the level of eutrophication from each measure are being tracked by calculating the Carlson trophic state index

  1. Sediment Deposition into a Valley-Margin Lake in a Managed Floodplain, Catahoula Lake, Louisiana, USA

    NASA Astrophysics Data System (ADS)

    Keim, R.; Latuso, K.; DeLaune, R. D.; Weindorf, D. C.

    2014-12-01

    Sediment sources to valley-margin lakes vary spatially and temporally depending on relative dominance of the main or tributary rivers. Catahoula Lake is the largest valley-margin lake in the lower Mississippi River Alluvial Valley and is hydrologically influenced by backwaters of the Mississippi and Red rivers and headwaters of the Little River. Our objective was to understand effects of hydrological management of the floodplain and the lake itself on lake sediments and recent changes in vegetation. Comparison of 137Cs profiles with prior 210Pb and 14C profiles indicates the recent deposition rate has been low (0.3 cm/yr) but triple that prior to settlement. Sediment chemistry profiles indicate dominance of acidic coastal-plain sediments from the tributary Little River in the past ~60 yr, but spatially mixed influence of acidic and neutral, Mississippi-Red sediments prior to that. We conclude that a century of increasing hydrologic management of the Mississippi and Red rivers has disconnected Catahoula Lake from their sedimentary influence and that the consequent change in chemical composition of surficial sediments may be contributing to ecologic changes in the lake.

  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. 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.

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

    EPA Science Inventory

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

  5. Chitinase genes in lake sediments of Ardley Island, Antarctica.

    PubMed

    Xiao, Xiang; Yin, Xuebin; Lin, Jian; Sun, Liguang; You, Ziyong; Wang, Peng; Wang, Fengping

    2005-12-01

    A sediment core spanning approximately 1,600 years was collected from a lake on Ardley Island, Antarctica. The sediment core had been greatly influenced by penguin guano. Using molecular methods, the chitinolytic bacterial community along the sediment core was studied over its entire length. Primers targeting conserved sequences of the catalytic domains of family 18 subgroup A chitinases detected group A chitinases from a wide taxonomic range of bacteria. Using quantitative competitive PCR (QC-PCR), chitinase gene copies in each 1-cm section of the whole sediment column were quantified. QC-PCR determination of the chitinase gene copies indicated significant correlation with phosphorus and total organic carbon concentration, suggesting a historical connection between chitinase gene copies and the amount of penguin guano input into the lake sediment. Most of the chitinase genes cloned from the historic sediment core were novel. Analysis of the chitinase gene diversity in selected sediment layers and in the fresh penguin deposits indicated frequent shifts in the chitinolytic bacterial community over time. Sequence analysis of the 16S rRNA genes of chitinolytic bacteria isolated from the lake sediment revealed that the isolates belonged to Janthinobacterium species, Stenotrophomonas species of gamma-Proteobacteria, Cytophaga species of the Cytophaga-Flexibacter-Bacteroides group, and Streptomyces and Norcardiopsis species of Actinobacteria. Chitinase gene fragments were cloned and sequenced from these cultivated chitinolytic bacteria. The phylogeny of the chitinase genes obtained from the isolates did not correspond well to that of the isolates, suggesting acquisition via horizontal gene transfer. PMID:16332766

  6. Temperature sensitivity of organic carbon mineralization in contrasting lake sediments

    NASA Astrophysics Data System (ADS)

    Gudasz, Cristian; Sobek, Sebastian; Bastviken, David; Koehler, Birgit; Tranvik, Lars J.

    2015-07-01

    Temperature alone explains a great amount of variation in sediment organic carbon (OC) mineralization. Studies on decomposition of soil OC suggest that (1) temperature sensitivity differs between the fast and slowly decomposition OC and (2) over time, decreasing soil respiration is coupled with increase in temperature sensitivity. In lakes, autochthonous and allochthonous OC sources are generally regarded as fast and slowly decomposing OC, respectively. Lake sediments with different contributions of allochthonous and autochthonous components, however, showed similar temperature sensitivity in short-term incubation experiments. Whether the mineralization of OC in lake sediments dominated by allochthonous or autochthonous OC has different temperature sensitivity in the longer term has not been addressed. We incubated sediments from two boreal lakes that had contrasting OC origin (allochthonous versus autochthonous), and OC characteristics (C/N ratios of 21 and 10) at 1, 3, 5, 8, 13, and 21°C for five months. Compared to soil and litter mineralization, sediment OC mineralization rates were low in spite of low apparent activation energy (Ea). The fraction of the total OC pool that was lost during five months varied between 0.4 and 14.8%. We estimate that the sediment OC pool not becoming long-term preserved was degraded with average apparent turnover times between 3 and 32 years. While OC mineralization was strongly dependent on temperature as well as on OC composition and origin, temperature sensitivity was similar across lakes and over time. We suggest that the temperature sensitivity of OC mineralization in lake sediments is similar across systems within the relevant seasonal scales of OC supply and degradation.

  7. 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]. PMID:20138650

  8. Morphology and Sediment Transport Dynamics of the Selenga River Delta, Lake Baikal, Russia

    NASA Astrophysics Data System (ADS)

    Dong, T. Y.; Il'icheva, L.; Nittrouer, J. A.; Pavolv, M.

    2013-12-01

    elevation for ~60% of the delta above the modern flood stage. Progressing down the delta axis, however, there is a steady lowering of the terraces, and the downstream portion of the delta (~40% of the delta proximal to the lake) is regularly inundated by flood water. This portion of the delta therefore defines where modern development and aggradation is occurring. Using field measurements, a simple 1-D morphodynamic model is developed to calculate an annual sediment budget for the Selenga River, thus estimating sediment delivery to the delta. This model also helps define where important sediment grain size transition regions occur in relation to channel bifurcations. Overall, the Selenga delta represents a unique end-member compared to other delta systems worldwide, because the Selenga delta is undergoing an active phase of regression, occurring as a result of either a relative base level fall, or perhaps reduced sediment supply relative to transport capacity. This delta phase produces substantial local sediment sourcing through erosion of relict (terraced) delta deposits, and this cannibalization process exerts important morphological controls on the modern morphology and stratigraphy.

  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. 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.

  12. Chemical lake restoration products: sediment stability and phosphorus dynamics.

    PubMed

    Egemose, Sara; Reitzel, Kasper; Andersen, Frede Ø; Flindt, Mogens R

    2010-02-01

    Laboratory experiments with sediments from three shallow Danish lakes were conducted to evaluate the effects of chemical lake restoration products during resuspension. Phosphorus (P) removal, sediment stability, sediment consolidation and color reduction were studied over time. The investigated products were aluminum (Al), Phoslock (a commercial bentonite product coated with lanthanum) and a combination of Al covered with bentonite (Al/Ben). All treatments effectively reduced the P concentration in the water. However, the treatments containing Al reduced the P concentration immediately after resuspension, whereas Phoslock required several days after resuspension to reduce the P concentration. Especially Phoslock, but also Al/Ben, increased the sediment stability threshold by 265% and 101%, respectively, whereas Al had no stabilizing effect. The fresh Al floc was resuspended 5x easier than untreated sediment. The largest consolidation of the sediment occurred with addition of Phoslock, followed by Al/Ben, while Al alone had no effect. Enhanced consolidation may be of importance for macrophyte colonisation of organic sediment. Phoslock improved the light climate moderately by removing color, whereas Al was very effective in removing color. Ben/Al showed intermediate effects on color reduction. These findings are important when decisions are made on restoration method for a specific lake, which may be more or less wind exposed. PMID:20055487

  13. 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...

  14. 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.

  15. 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.

  16. 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.

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

    PubMed

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

    2002-07-01

    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. PMID:12109471

  18. Sulfhydrolase activity in sediments of wintergreen lake, kalamazoo county, michigan.

    PubMed

    King, G M; Klug, M J

    1980-05-01

    The hydrolysis of p-nitrophenyl sulfate, p-nitrocatechol sulfate, and [S]sodium dodecyl sulfate was examined in anoxic sediments of Wintergreen Lake, Michigan. Significant levels of sulfhydrolase activity were observed in littoral, transition, and profundal sediment samples. Rates of sulfate formation suggest that the sulfhydrolase system would represent a major source of sulfate within these sediments. Sulfate formed by ester sulfate hydrolysis can support dissimilatory sulfate reduction as shown by the incorporation of S from labeled sodium dodecyl sulfate into H(2)S. Sulfhydrolase activity varied with sediment depth, was greatest in the littoral zone, and was sensitive to the presence of oxygen. Estimations of ester sulfate concentrations in sediments revealed large quantities of ester sulfate ( approximately 30% of total sulfur). Both total sulfur and ester sulfate concentrations varied with the sediment type and were two to three orders of magnitude greater than the inorganic sulfur concentration. PMID:16345573

  19. 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

  20. Sedimentology and geomorphology of a relict lacustrine system in Tingri, Tibet, China

    NASA Astrophysics Data System (ADS)

    Chiu, H.; Switzer, A. D.; Aitchison, J.

    2010-12-01

    A patchy sequence of near horizontal sedimentary deposits composed of consolidated carbonate-rich laminated gravelly sand and silt are exposed on the hill slopes near Tingri, Tibet, China. They are classified as mid- to late-Pleistocene and Holocene lacustrine deposits in Chinese geological maps, but the style and nature of lacustrine deposition and the facies associations in the sequence have never been reported. This study presents a number of sections in the locality showing the varied sedimentology of the deposits. The deposits are interpreted as relict sandy or gravelly dune ridges and plains, salt pans, prograded deltas, and lacustrine sediments. Interpretation was primarily based on a comparison with modern inland lakes in the Tibetan Plateau as analogues of processes in arid mountain lake systems. Relict dune ridges appear on the margins of many Tibetan inland lakes where the highly erosive regime allowed an abundant supply of gravels and sand to deposit along lake shorelines. The strong winds in Tibet have also allowed high to medium energy shoreline systems to develop in exposed areas. The high gravel and carbonate content in the gravelly ridges provided ample resistance to erosion and they often remain a topographically pronounced feature after lake drainage. Salt pans and gravelly or sandy ridge fields are also left after lake regression along with rare lacustrine deltas represented by the lakeward prograding beds. Laminated shelly sand or silt preserved in pockets near the valley floor characterise deposition at deeper lacustrine regimes. At Tingri the exposures of the palaeoshoreline deposits can reach 20 m in thickness and are identified at an elevation ranging from 4286 to 4404 masl. Although patchy in occurrence the sequence suggests a relatively long lived relict lake system. The timing of lake phases is poorly constrained by optically stimulated luminescence mid-to-late Pleistocene and Holocene. A number of incised channels are observed in

  1. Antioxidant Responses of Vallisneria asiatica to Eutrophic Sediments in Lake Taihu, China.

    PubMed

    Kang, Caixia; Kuba, Takahiro; Hao, Aimin; Iseri, Yasushi

    2015-08-01

    Three kinds of representative sediments were obtained from a macrophyte-dominated bay (East Lake Taihu) and two algae-dominated regions (Western Lake Taihu and Meiliang Bay). Physiological responses of Vallisneria asiatica to these sediments were compared. Results from 20 days exposures showed no obvious differences in malondialdehyde (MDA) in roots, while the MDA content in leaves of plants exposed to Western Lake Taihu sediment was significantly (p<0.05) higher than those exposed to the other two sediments. In comparison to the other two sediments, plants exposed to Western Lake Taihu sediment showed significantly lower (p<0.05) superoxide dismutase in roots and leaves on the 10th and 40th day. On the 40th day, root catalase (CAT) activities in V. asiatica from Western Lake Taihu and Meiliang Bay sediments were lower than that from East Lake Taihu sediment, while leaf CAT activity in V. asiatica from Western Lake Taihu sediment was higher than that from East Lake Taihu sediment (p<0.05). Western Lake Taihu sediment caused more serious oxidative stress in V. asiatica than East Lake Taihu sediment. Results indicated eutrophic sediment was a contributing factor in the disappearance of V. asiatica in Western Lake Taihu. PMID:26070371

  2. 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

  3. 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...

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. Suspended-sediment loads and reservoir sediment trap efficiency for Clinton Lake, Kansas, 2010-12

    USGS Publications Warehouse

    Juracek, Kyle E.

    2013-01-01

    Continuous streamflow and turbidity data collected from October 1, 2010, to September 30, 2012, at a site upstream and downstream from Clinton Lake, Kansas, were used to compute the total suspended-sediment load delivered to and released from the reservoir as well as the sediment trap efficiency for the reservoir. Ongoing sedimentation is inhibiting the ability of Clinton Lake to serve several purposes including flood control, water supply, and recreation. The inflow suspended-sediment load was substantially larger than the outflow load and most of the suspended-sediment load was delivered during short-term, high-discharge periods. Respectively, the total 2-year inflow and outflow suspended-sediment loads were computed to be 44.4 and 1.49 million pounds. Sediment trap efficiency for the reservoir was estimated to be 97 percent. The mean annual suspended-sediment yield from the upstream basin was estimated to be 60,500 pounds per square mile. Because this study was completed during a drought, the estimated inflow suspended-sediment load and suspended-sediment yield likely are substantially less than what would occur during a period of average or above average precipitation and runoff.

  9. 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.

  10. 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.

  11. The origin and biogeochemistry of organic matter in surface sediments of Lake Shihwa and Lake Hwaong

    NASA Astrophysics Data System (ADS)

    Won, Eun-Ji; Cho, Hyen-Goo; Shin, Kyung-Hoon

    2007-12-01

    To understand the origin and biogeochemistry of the organic matter in surface sediments of Lake Shihwa and Lake Hwaong, organic nitrogen, inorganic nitrogen, labile organic carbon, and residual organic carbon contents as well as stable isotope ratios for carbon and nitrogen were determined by KOBr-KOH treatment. Ratios of organic carbon to organic nitrogen (Corg/Norg) (mean = 24) were much higher than ratios of organic carbon to total nitrogen (Corg/Ntot) (mean=12), indicating the presence of significant amounts of inorganic nitrogen in the surface sediments of both lakes. Stable isotope ratios for organic nitrogen were, on average, 5.2‰ heavier than ratios of inorganic nitrogen in Lake Shihwa, but those same ratios were comparable in Lake Hwaong. This might be due to differences in the origin or the degree of degradation of sedimentary organic matter between the two lakes. In addition, stable isotope ratios for labile organic carbon were, on average, 1.4‰ heavier than those for residual organic carbon, reflecting the preferential oxidation of13C-enriched organic matter. The present study demonstrates that KOBr-KOH treatment of sedimentary organic matter can provide valuable information for understanding the origin and degradation state of organic matter in marine and brackish sediments. This also suggests that the ratio of Corg/Norg and stable isotope ratios for organic nitrogen can be used as indexes of the degree of degradation of organic matter.

  12. Recent sediment geochemistry of an alkaline lake: Lake Acigöl (Denizli), SW Anatolia Turkey

    NASA Astrophysics Data System (ADS)

    Budakoglu, M.; Karaman, M.; Karabel, S. B.; Geredeli, S. G.; Bulbul, A.; Kurt, H.; Uzasci, S.; Kan, A.; Akay, A. K.; Yilmaz, F. R.; Gumus, L.; Civas, M.; Sevis, C.; Kumral, M.

    2012-04-01

    Lake Acıgöl (Denizli) is one of the largest alkaline lake in Turkey. Surface, and shallow core samples was studied to determine the effects of riverine and aeolian processes on sediment physical properties and sediment geochemistry. Total organic carbon, total nitrogen content and major and minor element geochemistry of Lake Acıgöl sediments were investigated. Major (Si, Ti, Al, Fe, Mg, Ca, K, Na, P, S) and trace elements (Mn, As, V, Cr, Ni, Cu, Zn, Sr, Y, Zr, Ba, Pb) showed significant differences in bulk chemical composition between the surface and shallow core samples. Sediment properties were examined by water content, loss-on-ignition (LOI). While most of core samples characteristic with relative LOI increase from bottom towards sediment surface, limited core samples that were taken from eastern shore of the lake show increase of LOI values from sediment surface towards bottom, suggesting shallow water levels, aeolian and dentritic riverine inputs on a regional scale. The Fe/Mn ratio was calculated to study changes in the redox potential. Distribution of Fe, Mn, and S concentration were related to redox condition of lake sediment and are due to mobilization of these elements in the pore waters. Calculated two particulate ratios (C:N and N:P) indicate predominantly lacustrine origin. Vertical changes of heavy metals occur in the all shallow downcore profiles, although the concentrations keep to ppm levels. Principal components analysis (PCA) was also used to examine all studied parameters and intercorrelations among the variables.

  13. 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.

  14. 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.

  15. 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. PMID:26111964

  16. Early Eutrophication in the Lower Great Lakes: New Evidence from Biogenic Silica in Sediments

    NASA Astrophysics Data System (ADS)

    Schelske, Claire L.; Stoermer, Eugene F.; Conley, Daniel J.; Robbins, John A.; Glover, Rebecca M.

    1983-10-01

    New evidence from studies of biogenic silica and diatoms in sediment cores indicates that eutrophication in the lower Great Lakes resulted from nutrient enrichment associated with early settlement and forest clearance. Diatom production peaked from 1820 to 1850 in Lake Ontario, at about 1880 in Lake Erie, but not until 1970 in Lake Michigan. This is the first reported sediment record of the silica-depletion sequence for the Great Lakes.

  17. Enhancement of sediment phosphorus release during a tunnel construction across an urban lake (Lake Donghu, China).

    PubMed

    Wang, Siyang; Li, Hui; Xiao, Jian; Zhou, Yiyong; Song, Chunlei; Bi, Yonghong; Cao, Xiuyun

    2016-09-01

    Tunnel construction in watershed area of urban lakes would accelerate eutrophication by inputting nutrients into them, while mechanisms underlying the internal phosphorus cycling as affected by construction events are scarcely studied. Focusing on two main pathways of phosphorus releasing from sediment (enzymatic mineralization and anaerobic desorption), spatial and temporal variations in phosphorus fractionation, and activities of extracellular enzymes (alkaline phosphatase, β-1,4-glucosidase, leucine aminopeptidase, dehydrogenase, lipase) in sediment were examined, together with relevant parameters in interstitial and surface waters in a Chinese urban lake (Lake Donghu) where a subaqueous tunnel was constructed across it from October 2013 to July 2014. Higher alkaline phosphatase activity (APA) indicated phosphorus deficiency for phytoplankton, as illustrated by a significantly negative relationship between APA and concentration of dissolved total phosphorus (DTP). Noticeably, in the construction area, APAs in both sediment and surface water were significantly lower than those in other relevant basins, suggesting a phosphorus supply from some sources in this area. In parallel, its sediment gave the significantly lower iron-bound phosphorus (Fe(OOH)∼P) content, coupled with significantly higher ratio of iron (II) to total iron content (Fe(2+)/TFe) and dehydrogenase activities (DHA). Contrastingly, difference in the activities of sediment hydrolases was not significant between the construction area and other basins studied. Thus, in the construction area, subsidy of bioavailable phosphorus from sediment to surface water was attributable to the anaerobic desorption of Fe(OOH)∼P rather than enzymatic mineralization. Finally, there existed a significantly positive relationship between chlorophyll a concentration in surface water and Fe(OOH)∼P content in sediment. In short, construction activities within lakes may interrupt cycling patterns of phosphorus across

  18. 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

  19. 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. PMID:27384227

  20. 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

  1. 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

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. Metals associated with suspended sediments in lakes Erie and Ontario, 2000-2002.

    PubMed

    Marvin, Chris; Charlton, Murray; Milne, Jacqui; Thiessen, Lina; Schachtschneider, Joanne; Sardella, Gino; Sverko, Ed

    2007-07-01

    Sediment traps were deployed in the three major basins of Lake Erie, and the central (Mississauga) basin of Lake Ontario, and refurbished seasonally over the period 2000-2002. In Lake Ontario, sediment down-flux rates and corresponding contaminant down-flux rates were highest in winter during periods of unstratified thermal conditions, and generally increased with depth due to the influence of resuspended bottom sediments during all sampling periods. Lake Ontario suspended sediments exhibited the highest concentrations of metals; concentrations of mercury and lead frequently exceeded guideline values for bottom sediments. Contaminant levels in Lake Ontario suspended sediments were similar to concentrations in bottom sediments in the same area. There was a spatial trend toward higher suspended sediment metals concentrations from the eastern basin to the western basin of Lake Erie, which is similar to the trend in bottom sediment contamination. In the eastern basin of Lake Erie, which is the deepest area of the lake, there was no trend in down-flux rate with depth in 2001; however, down-flux rates increased with depth in 2002. Suspended sediments in the western basin of Lake Erie were determined to be largely resuspended bottom sediments; all western basin samples collected in the study exceeded the guideline value for mercury (0.486 microg/g). PMID:17057964

  7. Associations between degraded benthic communities and contaminated sediments: Sabine Lake, Lake Pontchartrain, and Choctawhatchee Bay

    SciTech Connect

    Engle, V.D.; Summers, J.K.; Macauley, J.M.

    1994-12-31

    The Environmental Monitoring and Assessment Program for Estuaries (EMAP-E) in the Gulf of Mexico supplements its base sampling effort each year with localized, intensive spatial sampling in selected large estuarine systems. By selecting random locations within 70 km{sup 2} hexagonal areas, individual estuaries were sampled using EMAP methods but at four times the density as base sampling. In 1992, 19 sites were sampled in Lake Pontchartrain, Louisiana. In 1 993, 18 sites were sampled in Sabine Lake, Texas and 12 sites were sampled in Choctawhatchee Bay, Florida. At all sites, sediment grabs were taken and analyzed for benthic species composition and abundance, for toxicity to Ampelisca, and for organic and inorganic sediment contaminants. An indicator of biotic integrity, the benthic index, was calculated to represent the status of benthic communities. A series of statistical techniques, such as stepwise regression analysis, were employed to determine whether the variation in the benthic index could be associated with variation in sediment contaminants, sediment toxicity, or levels of dissolved oxygen. Spatial distributions of these parameters were examined to determine the geographical co-occurrence of degraded benthic communities and environmental stressors. In Lake Pontchartrain, for example, 85% of the variation in the benthic index was associated with decreased levels of dissolved oxygen, and increased concentrations of PCBs, alkanes, copper, tin, and zinc in the sediments.

  8. Characterization of major offensive odorants released from lake sediment

    NASA Astrophysics Data System (ADS)

    Susaya, Janice; Kim, Ki-Hyun; Chang, Yoon-Seok

    2011-02-01

    The amount of odorants effused from Lake Sihwa during the low tide period was estimated using sediment samples collected from various sites. A wide variety of odorants released from lake sediment were measured such as reduced sulfur compounds (RSCs), aldehydes, nitrogenous compounds, volatile organic compounds (VOCs), and volatile fatty acids (VFAs). A comparison of emission rates (μg m -2 min -1) showed large mean values from such species as NH 3 (14,550), toluene (370), and DMS (106), while the lowest values were seen from VFAs and some VOCs. If their emission concentrations are converted into odor intensity (OI), the OI values were dominated by such odorants as NH 3 (2.07), H 2S (1.65), DMS (1.80), acetaldehyde (1.52), butyric acid (1.59), butyraldehyde (1.28), isovaleric acid (1.15), and valeric acid (0.78). The dilution to threshold (D/T) ratio derived on the basis of the air dilution sensory (ADS) test yielded a mean of 62 (range: 10-173); 19 out of 21 samples were seen to exceed the guideline D/T value of 15. The sum of odor intensities derived from individual odorants exhibited strong compatibilities with the D/T ratio ( r2 = 0.87; α = 0.003). The overall results of this study confirm that the sediment can play an important role in the malodor phenomenon in the area surrounding the Lake Sihwa.

  9. The vertical variation of nutrients in a sediment core of Delong Lake reveals the anthropogenic effect.

    PubMed

    Guan, Ying; Zang, Shuying; Xiao, Haifeng

    2014-05-01

    Phosphorus content and its species were studied for the core sediments of Delong Lake, using the SMT sequential extraction method, and then were correlated to the contents of total nitrogen and organic matter. According to (210)Pb and (137)Cs dating, the historical profiles of 33 cm core sediments were generated. The objective of this study was to understand how nutrients of lake sediments evolved in order to get insights into the effect of human activities on their sedimentary history. The nutrients contents in the core sediments slowly increased after 1957, showing the human activity influence the natural deposition of the lake sediment. From 1978 to 1985, various nutrients in the lake sediment rapid increased, showing that the human activities strengthened. From 2003 to now, most of nutrients in the sediment rapidly increased and significantly modified the natural deposition of the lake sediment. PMID:24468926

  10. Characterization of anaerobic heterotrophic bacteria isolated from freshwater lake sediments.

    PubMed

    Molongoski, J J; Klug, M J

    1976-01-01

    Strict anaerobic culture techniques were used to quantitatively and qualitatively evaluate the anaerobic heterotrophic bacteria present at the sediment-water interface of hyperutrophic Wintergreen Lake (Augusta, Mich.). Anaerobic plate counts remained constant from March through December, 1973, ranging from 2.4 X 10(6) to 5.7 X 10(6) organisms/g (dry weight) of sediment. The isolatable bacteria represented a small percentage of the total microbial community, which was shown by direct microscopic counts to be 2.0 X 10'' organisms/g (dry weight) of sediment during June and July. Bacteria of the genus Clostridium dominated the isolates obtained, accounting for 71.8% of the 960 isolates examined. A single species, Clostridium bifermentens, comprised 47.7% of the total. Additional bacterial groups and the percentage in which they were isolated included: Streptococcus sp. (10.8%), unidentified curved rods (9.5%y, gram-positive nonsporing rods (5.6%), and motile gram-negative rods (1.9%). Temperature growth studies demonstrated the ability of all the isolates to grow at in situ sediment temperatures. Gas-liqid radiochromatography was used to determine the soluble metabolic end products from [U-14C]glucose and a U-14C-labeled amino acid mixture by representative sedimentary clostridial isolates and by natural sediment microbial communities. At in situ temperatures the natural sediment microflora produced soluble fermentative end products characteristic of those elaborated by the clostridial isolates tested. These results are considered strong presumptive evidence that clostridia are actively metabolizing in the sediments of Wintergreen Lake. PMID:942211

  11. 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

  12. 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...

  13. Effects of Local Farming and Deforestation on Sediment Discharge Inferred From Sediment Accumulation Rates and Patterns in Lake Core Records From Coastal Lake Tanganyika, East Africa

    NASA Astrophysics Data System (ADS)

    Strickler, M. L.; Lezzar, K. E.; Soreghan, M.; Cohen, A. S.; Swarzenski, P. W.; Berke, M.; McHeni, M.; Gunderson, K.; Allen, K.; Palke, A.; Modesta, M.; Nkotagu, H.

    2006-12-01

    Lake Tanganyika is the oldest and largest of the East African rift lakes and vital to the economy of the surrounding villages and countries. Deforestation around the lake causes many negative effects from an increased sediment flux and has changed dramatically as a function of population. Increases in inorganic sediment flux from deforested watersheds and an associated decrease in organic sediment flux may negatively impact the viability of littoral habitats in the lake. This study examines the interrelationship between deforestation on streams that feed into Lake Tanganyika and sedimentation offshore. We mapped stream morphology of two distinct streams: Kalande (Gombe Stream National Park), and Ngelwa (deforested). An offshore core was collected from the lake bottom just offshore of the deforested Ngelwa stream at a water depth of 106m and dated using 14C and 210Pb geochronologic methods. In addition, multiple laboratory analyses were performed on the core and within the streams to help constrain sedimentation and deforestation effects. Three distinct units within the core correlate to reflect changes in sedimentation (higher rates as deforestation continues) in addition to a shift from dry, low lake level conditions to wet, high lake levels as evidenced by shifts in core lithologies, diatom taxonomy and content, magnetic susceptibility, and clastic particle size. Streambed and suspended sediment analyses reflect high levels of erosion in deforested watersheds coupled with changes in dissolved nutrients in the water (silica, orthophosphate), which may suggest an overall diminished level of ecosystem function in deforested and heavily farmed watersheds.

  14. Environmental changes on the Balkans recorded in the sediments from lakes Prespa and Ohrid

    NASA Astrophysics Data System (ADS)

    Wagner, B.; Vogel, H.; Zanchetta, G.; Sulpizio, R.

    2010-05-01

    Lakes Prespa and Ohrid on the Balkans are considered to be amongst the oldest lakes in Europe. Both lakes are hydraulically connected via karst aquifers. From Lake Ohrid, several up to ca. 15 m long sediment records were studied during the past years. In this study, a first long sediment record from Lake Prespa was studied in order to shed more light on the influence of Lake Prespa on Lake Ohrid and the environmental history of the region. Radiocarbon dating and the occurrence of 3 dated tephra layers provide a good age control and indicate that the 10.5 m long sediment record reaches back to 48 ka. The comparison of the results from this study with those from former studies of the Lake Ohrid cores indicates that Lake Prespa is more susceptible to environmental changes due to its lower volume and water depth. Glacial sedimentation is characterized by low organic matter contents and absence of carbonates in the sediments, which indicate oligotrophic conditions in both lakes. Holocene sedimentation is characterized by particularly high carbonate contents in Lake Ohrid and by particularly high organic matter contents in Lake Prespa, which indicate a shift towards more mesotrophic conditions in the latter. Long-term environmental changes and short-term events, such as the Heinrich events during the Pleistocene or the 8.2 cooling event during the Holocene, are well recorded in both lakes, but partly expressed in different proxies.

  15. [Vertical Distribution Characteristics and Analysis in Sediments of Xidahai Lake].

    PubMed

    Duan, Mu-chun; Xiao, Hai-feng; Zang, Shu-ying

    2015-07-01

    The organic matter (OM), total nitrogen (TN), total phosphorus (TP), the morphological changes of phosphorus and the particle size in columnar sediment core of Xidahai Lake were analyzed, to discuss the vertical distribution characteristics and influencing factors. The results showed that the contents of OM, TN and TP were 0. 633% -2. 756%, 0. 150% -0. 429% and 648. 00 - 1 480.67 mg . kg-1 respectively. The contents of Ca-P, IP and OM changed less, the contents of Fe/Al-P, OP, TP and TN fluctuated from 1843 to 1970; The contents of Ca-P, IP and TP tended to decrease, the contents of Fe/Al-P, OP and OM first decreased and then increased to different degree, TN fluctuated largely from 1970 to 1996; The nutrient elements contents showed relatively large fluctuation from 1996 to 2009, the average contents of Fe/Al-P, OP and OM were the highest in the three stages. The sediment core nutrients pollution sources were mainly from industrial wastewater, sewage and the loss of fertilizers of Xidahai Lake. The ratio of C/N in the sediments showed that organic matter was mainly from aquatic organisms. The sediment particle size composition was dominated by clay and fine silt. The correlation studies showed that Ca-P, IP and TP were significantly positively correlated, showing that the contribution of Ca-P to IP and TP growth was large. PMID:26489314

  16. Ephemerality of discrete methane vents in lake sediments

    USGS Publications Warehouse

    Scandella, Benjamin P.; Pillsbury, Liam; Weber, Thomas; Ruppel, Carolyn; 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.

  17. 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.

  18. 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 ...

  19. 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

  20. Fremont Lake, Wyoming--some aspects of the inflow of water and sediment

    USGS Publications Warehouse

    Emmett, W.W.; Averett, R.C.

    1989-01-01

    Fremont Lake is a large (20.6 sq km), deep lake (185 m) in western Wyoming. Average annual inflow of water is about 5.1 cu meters/sec, and this discharge is equaled or exceeded about 23% of the time. Annual instantaneous peak flows of Pine Creek usually exceed 30 cu m/sec and the 100-year flood is about 80 cu m/sec. About 800 tons of sediment are delivered to the lake annually; annual deposition of sediment in the northern lake area throughout the last 10,000 years about equals contemporary values of sediment inflow. Only small quantities of fine-gradient sediment are transported beyond the delta at the northern end of the lake. Current rates of deposition in the delta are about 1 to 3 mm/yr. Sediment in the delta generally is sand size; elsewhere in the lake, sediment generally is clay and silt size. (USGS)

  1. Distribution of polycyclic aromatic hydrocarbons in sediments of Akaki River, Lake Awassa, and Lake Ziway, Ethiopia.

    PubMed

    Mekonnen, Kebede Nigussie; Chandravanshi, Bhagwan Singh; Redi-Abshiro, Mesfin; Ambushe, Abayneh Ataro; McCrindle, Robert Ian; Moyo, Stanley

    2015-07-01

    The quantification of 14 polycyclic aromatic hydrocarbons (PAHs) was carried out in sediment samples collected from Akaki River, Lake Awassa, and Lake Ziway, Ethiopia. The concentration of PAHs in the samples was determined using gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode, after microwave-assisted extraction (MAE), using acetone/n-hexane (1:1, v/v) mixture. The accuracy of the method was determined by extracting and analyzing New York/New Jersey waterway sediment standard reference material (SRM 1944). The measured concentrations of PAHs in SRM 1944 agreed well with the certified values. In samples from Akaki River, Lake Awassa, and Lake Ziway, the total content of PAHs determined ranged from 0 to 3070 ng/g (average 534 ng/g), 24.9 to 413 ng/g (average 169 ng/g), and 15.0 to 305 ng/g (average 175 ng/g), respectively. Source ratios indicated that the PAHs were mainly from petrogenic origin. Sediments from all sampling sites indicated negligible levels of toxicity with no risk of adverse biological effects. PMID:26122125

  2. 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

  3. 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

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

    PubMed

    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

  5. Integration of Hydrologic, Sediment Yield, Sediment Delivery, Hydrodynamic and Sediment Transport Models in Large Great Lakes Watersheds

    NASA Astrophysics Data System (ADS)

    Brunton, A.; Nairn, R.; Selegean, J.

    2004-12-01

    Computational tools to evaluate surface and subsurface water flow and sediment transport are commonly used by environmental and engineering practitioners. However, different parts of the hydrologic system (e.g. hillslope overland flow, groundwater, river channel flow) are often treated separately and at disparate spatial and temporal scales. Overland flow models typically have no explicit channel representation and vice-versa, making integrated assessments of water and sediment delivery from catchment to channel difficult. This is problematic when appraising the influence of land use change (urbanization, modification of riparian buffer strips, changes in tillage and forestry practices etc.) on catchment sediment movement and river flood hydrographs. A 'budgetary' approach was taken to defining the sources and sinks of water and sediment within large catchments in the Great Lakes area under a variety of land uses. These budgets were derived from existing datasets including digital elevation models, river flow and sediment load records, and dam sedimentation surveys. Numerical models of watershed hydrology and sediment delivery, 2-D river flow and sediment transport were constructed to develop a general understanding of the hydrologic and geomorphic behavior of these systems, and to predict the effects of changing land use and riparian buffer zone modification. Models were calibrated against river flow and sediment transport records, reservoir sedimentation surveys and harbor dredging records. The challenges and benefits of combining these diverse approaches and their implementation in best management practices are discussed.

  6. 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.

  7. 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

  8. 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.

  9. 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

  10. A New Method for the Determination of Annual Sediment Fluxes from Varved Lake Sediments

    NASA Astrophysics Data System (ADS)

    Francus, P.; Massa, C.; Lapointe, F.

    2013-12-01

    Calculation of sediment mass accumulation rates instead of thickness accumulation is preferable for paleoclimatic reconstruction as it eliminates the effects of dilution and compaction. Annually laminated lake sediment sequences (varved) theoretically allow for the estimation of sediment fluxes at annual scale, but the calculation is limited by discrete bulk density measurements, often carried out at a much lower resolution (usually 1 cm) than the varves (ranging from 0.07 to 27.3 mm, average 1.84 mm according to Ojala et al. 2012). Since many years the development of automated logging instruments made available continuous and high resolution sediment property data, in a non-destructive fashion. These techniques can easily be used to extract the physical and chemical parameters of sediments at the varve scale (down to 100 μm). Here we present a robust method to calculate annual sediment fluxes from varved lake sediments by combining varves thickness measurements to core logging data, and provide an example for its applications. Several non-destructive densitometric methods applied to the Strathcona Lake sediment, northern Ellesmere Island, Canada (78°33'N; 82°05'W) were compared: Hounsfield Units from a CT-Scan, coherent/incoherent ratio and X-ray radiography (of both split core and sediment slabs, from an Itrax core Scanner), and gamma ray attenuation density. Core logging data were statistically compared to 400 discrete measurements of dry bulk density, wet bulk density and water content performed at 2 mm contiguous intervals. A very strong relationship was found between X-ray grey level on sediment slab and dry bulk density. Relative X-ray densities, at 100μm resolution, were then successfully calibrated against real densities. The final step consisted in binning the calibrated densities to the corresponding varve thickness and then to calculate the annual mass accumulation rates by multiplying the two parameters for each varve year. Strathcona Lake is

  11. Varved Sediments of Maar Lake Ranu Klindungan, East Java

    NASA Astrophysics Data System (ADS)

    Pirrung, M.; Buechel, G.; Scharf, B.; Treutler, H.; Witkowski, A.

    2001-05-01

    Ranu Klindungan (7.725° S, 113.02° E, 10 m a.s.l.) is a maar lake 1550 m in diameter in the coastal lowlands at the northern foot of the Tengger Caldera in East Java, Indonesia. The southern half of the lake is surrounded by a tephra wall up to 50 m high, whereas towards the north topography rises only some meters above lake level. Fresh maar tephra consist of ash and lapilli layers with cauliflower-bombs and -lapilli. The lake has no permanent inflow but 4 effluents with a total discharge of 450 L/s which underlines the importance of groundwater access on subaquatic slopes. Echolot profiles reveal a flat central area 750 m in diameter at 126 m depth and on the steep slopes several slides are visible. The eutrophic, oligomictic lake has an epilimnion in the uppermost 5 m and an anoxic hypolimnion below 20 m. Profundal sediments are composed of diatom gyttja with frequent turbidites. In thin sections, light-dark alternation in slack water deposits reflects 1-6 mm thick cycles that have a lower, light biogenous part of intact planktonic diatom valves with an upwards increasing amount of carbonate crystals, ending with an almost pure carbonate layer, and an upper, dark terrigenous part of mineral grains and plant debris with some carbonate crystals and fragmented littoral diatom valves. These cycles are interpreted as annual varves: layers of diatoms and carbonate crystals are sedimented during the dry season June-October and terrigenous layers during the monsoon-rain season November-May. This is confirmed by 210Pb-excess ages determined after the constant initial concentration method. Distal turbidites contribute about half of the sediment thickness. This points to turbidity currents as major relief-forming process. Magnetic volume specific susceptibility is very high (maximum 1.4*10-2 SI) and clearly bound to fresh terrigenous material in turbidites. Variation of sedimentation rates and terrigenous input during the last 40 years will be discussed.

  12. 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. PMID:26711281

  13. 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

  14. 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.

  15. 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.

  16. Arsenic fractionation and contamination assessment in sediments of thirteen lakes from the East Plain and Yungui Plateau Ecoregions, China.

    PubMed

    Zan, Fengyu; Huo, Shouliang; Zhang, Jingtian; Zhang, Li; Xi, Beidou; Zhang, Lieyu

    2014-10-01

    Arsenic (As) fractions in the sediments of seven lakes from East Plain Ecoregion and six lakes from Yungui Plateau Ecoregion, China, were investigated. Results indicated that the total As concentrations in sediment samples of lakes of the East Plain Lake Ecoregion are higher than those of Yungui Plateau Lake Ecoregion. Residual As is the main fraction in sediment samples of lakes from both ecoregions, followed by reducible As and soluble or oxidizable As. The total As is correlated to oxidizable As and residual As in sediment samples from both lake ecoregions. As distribution in sediment samples of lakes of the East Plain Ecoregion appears to be affected by human activity, while the As origin mainly comes from natural sources in sediment samples of lakes in the Yungui Plateau Ecoregion. The potential ecological risk index and geoaccumulation index values suggest "low to moderate" risk degree and "unpolluted to moderately polluted" for As in the studied lake sediments. PMID:25288540

  17. 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. PMID:23644565

  18. Understanding Sediment Dynamics in a Shallow, Hypereutrophic Lake within the Middle St. Johns River: Lake Jesup, FL

    NASA Astrophysics Data System (ADS)

    Nielsen, S.; Anderson, W. T.; Corbett, D. R.; Fugate, D. C.; Scinto, L. J.; Thomas, S.; Brandt-Williams, S.

    2011-12-01

    Improved knowledge of sediment dynamics within a lake system is important for understanding lake water quality. This research was focused on an assessment of the vertical sediment flux in Lake Jesup, a shallow (1.3 m average depth) hypereutrophic lake of central Florida. Sediment dynamics were assessed at varying time scales (daily to weekly) to understand the transport of sediments from external forces; wind, waves, precipitation and/or runoff. Four stations were selected within the lake based on water depth and the thicknesses of unconsolidated (floc) and consolidated sediments. At each of these stations, a 10:1 high aspect ratio trap (STHA) was deployed to collect particulate matter for a one to two week period. The water and sediment samples were collected and analyzed for total carbon (TC), total phosphorus (TP) and total nitrogen (TN). Mass accumulation rates (MAR) collected by the traps varied from 77 to 418 g m-2 d-1 over seven deployments. TN, TP and TC sediment concentrations collected by the traps were consistently higher than the sediments collected by coring the lake bottom and is most likely associated with water column biomass.

  19. High resolution analysis of northern Patagonia lake sediments

    NASA Astrophysics Data System (ADS)

    Jarvis, S. W.; Croudace, I. W.; Langdon, P. G.; Rindby, A.

    2009-04-01

    Sediment cores covering the period from the last glacial maximum through the Holocene to the present have been collected from sites in the Chacubuco valley, southern Chile (around 47°08'S, 72°25'W, to the east of the North Patagonian Icecap). Cores were taken from five lakes and one recently dried lake bed. Short cores (0.2 to 0.5m), covering approximately the last two hundred years, were taken from all the lakes. Additionally, long sequences were obtained from one of the lakes and from the dried lake bed, the latter sequence extending back to the last glacial maximum as indicated by thick clay at the base. Each of the lakes are small-medium sized and are open systems situated at 300-1000m above sea level. The shorter cores comprise predominantly clastic gyttja but show a number of distinct changes in colour and chemical composition that suggest major environmental changes over the period of sediment accumulation. This is also reflected in variations in the loss on ignition of samples from the cores and in elemental profiles produced by scanning the cores with the Itrax micro-XRF corescanner at 200μm resolution. The long sequence from the dried lake bed has very low organic content glacial clay at the base, interpreted as last glacial maximum basal clay following determination in the field that this layer exceeded 2m in thickness. Similar sediments occur within a stratigraphically discrete section of approximately 14cm and may relate to a stadial event. The latter section also shows a drop in organic content and appears to be glacial clay incorporating some coarse sandy components indicative of detrital input from the catchment. The second long sequence, from a carbonate lake, includes two mineral layers indicating increased detrital input from the catchment. The deeper and thicker of these layers appears similar to the 14cm layer in the first long sequence, while the upper layer comprises a fine grain size indicative of rock flour and hence also of glacial

  20. Composition of Humic Acids of the Lake Baikal Sediments

    NASA Astrophysics Data System (ADS)

    Vishnyakova, O.; Chimitdorzhieva, G.; Andreeva, D.

    2012-04-01

    Humic substances are the final stage of the biogeochemical transformation of organic matter in the biosphere. Its natural compounds are found not only in soil, peat, coal, and sediments of basins. Chemical composition and properties of humic substances are determined by the functioning of the ecosystem as a whole. Therefore the study of the unique Lake Baikal sediments can provide information about their genesis, as well as the processes of organic matter transformation. For this purpose, preparations of humic acids (HA) were isolated by alkaline extraction method. The composition of HA was investigated by the elemental analyzer CHNS/O PerkinElmer Series II. Various located sediments of the Lake Baikal were the objects of the study: 1 - Chivyrkuisky Bay, 2 - Kotovo Bay, 3 - Selenga river delta near Dubinino village, 4 - Selenga river delta near Murzino village. Data on the elemental composition of HA in terms of ash-free portion show that the carbon content (CC) is of 50-53% with a maximum value in a sample 3, and minimum - in a sample 2. Such values are characteristic also for the soils with low biochemical activity. The hydrogen content is of 4,2-5,3%, a maximum value is in a sample 1. Data recalculation to the atomic percentages identified following regularities. The CC of HA is of 35-39 at. %. Hydrogen content is of 37-43 at. %. According to the content of these elements investigated substances are clearly divided into two groups: HA of the sediments of the Lake Baikal and river Selenga delta. The magnitude of the atomic ratio H/C can be seen varying degrees of condensation of the molecules of humic acids. The high atomic ratio H/C in HA of the former group indicates the predominance of aliphatic structures in the molecules. Humic acids of the later group are characterized by a low value H/C (<1), suggesting a large proportion of aromatic components in HA composition. In sediments of the Selenga river delta there is an addition of organic matter of terrigenous

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

    PubMed

    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 ([Formula: see text]-N, p < 0.01), silicate silicon ([Formula: see text]-Si, p < 0.01), nitrite nitrogen ([Formula: see text]-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

  2. 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

  3. 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...

  4. 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

  5. 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

  6. 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. PMID:19183821

  7. The behavior of acoustic waves in the lakes bottom sediments.

    NASA Astrophysics Data System (ADS)

    Krylov, Pavel; Nourgaliev, Danis; Yasonov, Pavel

    2016-04-01

    Seismic studies are used for various tasks, such as the study of the bottom sediments properties, finding sunken objects, reconstruction the reservoir history, etc. Multiple acoustic waves are an enormous obstacle in obtaining full seismic record. Multiples from the bottom of a body of water (the surface of the base of water and the rock or sediment beneath it) and the air-water surface are common in lake seismic data. Multiple reflections on the seismic cross-sections are usually located on the double distance from the air/water surface. However, sometime multiple reflections from liquid deposits cannot be generated or they reflected from the deeper horizons. It is observed the phenomenon of changes in reflectance of the water/weakly consolidated sediments acoustic boundary under the influence of the acoustic wave. This phenomenon lies in the fact that after the first acoustic impact and reflection of acoustic wave for some time the reflectance of this boundary remains close to 0. This event on a cross-section can explain by the short-term changes in the properties of bottom sediments under the influence of shock? acoustic wave, with a further reduction of these properties to the next wave generation (generation period of 2 seconds). Perhaps in these deposits occurs thixotropic process. The paper presents the seismic acoustic cross-sections of Lake Balkhash (Kazakhstan), Turgoyak (Russia). The work was carried out according to the Russia Government's Program of Competitive Growth of Kazan Federal University, supported by the grant provided to the Kazan State University for performing the state program in the field of scientific research, and partially supported by the Russian Foundation for Basic research (grants № 14-05-00785, 16-35-00452).

  8. Microbial Fe cycling and mineralization in sediments of an acidic, hypersaline lake (Lake Tyrell, Victoria, Australia)

    NASA Astrophysics Data System (ADS)

    Roden, E. E.; Blöthe, M.; Shelobolina, E.

    2009-12-01

    Lake Tyrrell is a variably acidic, hypersaline, Fe-rich lake located in Victoria, Australia. Terrestrial acid saline lakes like Lake Tyrrell may be analogs for ancient Martian surface environments, as well as possible extant subsurface environments. To investigate the potential for microbial Fe cycling under acidic conditions and high salt concentration, we collected sediment core samples during three field trips between 2006 and 2008 from the southern, acidic edge of the lake. Materials from the cores were used for chemical and mineralogical analyses, as well as for molecular (16S rRNA genes) and culture-based microbiological studies. Near-surface (< 1 m depth) pore fluids contained low but detectable dissolved oxygen (ca. 50 uM), significant dissolved Fe(II) (ca. 500 uM), and nearly constant pH of around 4 - conditions conducive to enzymatic Fe(II) oxidation. High concentrations of Fe(III) oxides begin accumulate at a depth of ca. 10 cm, and may reflect the starting point for formation of massive iron concretions that are evident at and beneath the sediment surface. MPN analyses revealed low (10-100 cells/mL) but detectable populations of aerobic, halophilic Fe(II)-oxidizing organisms on the sediment surface and in the near-surface ground water. With culture-dependent methods at least three different halotolerant lithoautotrophic cultures growing on Fe(II), thiosulfate, or tetrathionate from different acidic sites were obtained. Analysis of 16S rRNA gene sequences revealed that these organisms are similar to previous described gamma proteobacteria Thiobacillus prosperus (95%), Halothiobacillus kellyi (99%), Salinisphaera shabanense (95%) and a Marinobacter species. (98%). 16S rRNA gene pyrosequencing data from two different sites with a pH range between 3 and 4.5 revealed a dominance of gamma proteobacteria. 16S rRNA gene pyrosequencing libraries from both cores were dominated by sequences related to the Ectothiorhodospiraceae family, which includes the taxa

  9. Relict landscape resistance to dissection by upstream migrating knickpoints

    NASA Astrophysics Data System (ADS)

    Brocard, Gilles Y.; Willenbring, Jane K.; Miller, Thomas E.; Scatena, Frederik N.

    2016-06-01

    Expanses of subdued topographies are common at high elevation in mountain ranges. They are often interpreted as relict landscapes and are expected to be replaced by steeper topography as erosion proceeds. Preservation of such relict fragments can merely reflect the fact that it takes time to remove any preexisting topography. However, relict fragments could also possess intrinsic characteristics that make them resilient to dissection. We document here the propagation of a wave of dissection across an uplifted relict landscape in Puerto Rico. Using 10Be-26Al burial dating on cave sediments, we show that uplift started 4 Ma and that river knickpoints have since migrated very slowly across the landscape. Modern detrital 10Be erosion rates are consistent with these long-term rates of knickpoint retreat. Analysis of knickpoint distribution, combined with visual observations along the streambeds, indicates that incision by abrasion and plucking is so slow that bedrock weathering becomes a competing process of knickpoint retreat. The studied rivers flow over a massive stock of quartz diorite surrounded by an aureole of metavolcanic rocks. Earlier studies have shown that vegetation over the relict topography efficiently limits erosion, allowing for the formation of a thick saprolite underneath. Such slow erosion reduces streambed load fluxes delivered to the knickpoints, as well as bed load grain size. Both processes limit abrasion. Compounding the effect of slow abrasion, wide joint spacing in the bedrock makes plucking infrequent. Thus, the characteristics of the relict upstream landscape have a direct effect on stream incision farther downstream, reducing the celerity at which the relict, subdued landscape is dissected. We conclude that similar top-down controls on river incision rate may help many relict landscapes to persist amidst highly dissected topographies.

  10. 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.

  11. 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

  12. 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.

  13. 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...

  14. 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...

  15. Draft Genome of Janthinobacterium sp. RA13 Isolated from Lake Washington Sediment.

    PubMed

    McTaggart, Tami L; Shapiro, Nicole; Woyke, Tanja; Chistoserdova, Ludmila

    2015-01-01

    Sequencing the genome of Janthinobacterium sp. RA13 from Lake Washington sediment is announced. From the genome content, a versatile life-style is predicted, but not bona fide methylotrophy. With the availability of its genomic sequence, Janthinobacterium sp. RA13 presents a prospective model for studying microbial communities in lake sediments. PMID:25676775

  16. Draft Genomes of Two Strains of Flavobacterium Isolated from Lake Washington Sediment

    PubMed Central

    McTaggart, Tami L.; Shapiro, Nicole; Woyke, Tanja

    2015-01-01

    We report sequencing the genomes of two new Flavobacterium strains isolated from Lake Washington sediment. From genomic contents, versatile lifestyles were predicted but not bona fide methylotrophy. With the availability of their genomic sequences, the new Flavobacterium strains present prospective models for studying microbial communities in lake sediments. PMID:25700420

  17. Draft Genome of Pseudomonas sp. Strain 11/12A, Isolated from Lake Washington Sediment.

    PubMed

    McTaggart, Tami L; Shapiro, Nicole; Woyke, Tanja; Chistoserdova, Ludmila

    2015-01-01

    We announce here the genome sequencing of Pseudomonas sp. strain 11/12A from Lake Washington sediment. From the genome content, a versatile lifestyle is predicted but not one of bona fide methylotrophy. With the availability of its genomic sequence, Pseudomonas sp. 11/12A presents a prospective model for studying microbial communities in lake sediments. PMID:25700412

  18. Draft Genome of Pseudomonas sp. Strain 11/12A, Isolated from Lake Washington Sediment

    PubMed Central

    McTaggart, Tami L.; Shapiro, Nicole; Woyke, Tanja

    2015-01-01

    We announce here the genome sequencing of Pseudomonas sp. strain 11/12A from Lake Washington sediment. From the genome content, a versatile lifestyle is predicted but not one of bona fide methylotrophy. With the availability of its genomic sequence, Pseudomonas sp. 11/12A presents a prospective model for studying microbial communities in lake sediments. PMID:25700412

  19. Draft genomes of two strains of flavobacterium isolated from lake washington sediment.

    PubMed

    McTaggart, Tami L; Shapiro, Nicole; Woyke, Tanja; Chistoserdova, Ludmila

    2015-01-01

    We report sequencing the genomes of two new Flavobacterium strains isolated from Lake Washington sediment. From genomic contents, versatile lifestyles were predicted but not bona fide methylotrophy. With the availability of their genomic sequences, the new Flavobacterium strains present prospective models for studying microbial communities in lake sediments. PMID:25700420

  20. Draft Genome of Janthinobacterium sp. RA13 Isolated from Lake Washington Sediment

    PubMed Central

    McTaggart, Tami L.; Shapiro, Nicole; Woyke, Tanja

    2015-01-01

    Sequencing the genome of Janthinobacterium sp. RA13 from Lake Washington sediment is announced. From the genome content, a versatile life-style is predicted, but not bona fide methylotrophy. With the availability of its genomic sequence, Janthinobacterium sp. RA13 presents a prospective model for studying microbial communities in lake sediments. PMID:25676775

  1. 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.

  2. [Pollution Status and Migration of Mercury in the Sediments of Nansi Lake in Shandong Province].

    PubMed

    Cao, Fei-fei; Yang, Li-yuan; Pang, Xu-gui; Wang, Bing-hua; Wang, Yun-qian

    2015-05-01

    The content of mercury and fractions were determined, in order to discuss the pollution situation and migration ability of mercury in inflow rivers and surface sediments of Nansi Lake. The average content of mercury in the sediments of the Nansi Lake was 0.046 mg · kg(-1), significantly higher than the environmental background values, which showed that Nansi Lake suffered from mercury pollution. Mercury in sediments existed mainly in the residual fraction, accounting for 65. 15%. The proportion of non-residual fractions was relatively small, in the order of organic bound fraction (30.61%), extractable fraction (2.93%), and Fe/Mn oxide (1.31%). The spatial change of non-residual fractions was that Weishan Lake and Nanyang Lake had higher non-residual mercury content than Zhaoyang Lake and Dushan Lake, and the non-residual mercury had a certain potential ecological harm on Weishan Lake and Nanyang Lake. From the horizontal view, the mercury content in the surface sediments of Nansi Lake had visible difference and the pollution degree was different among sub-lakes, so horizontal migration of mercury was obvious. Vertically, the mercury content showed a trend of increasing from the bottom to the top in core sediments, which might be associated with social and economic conditions in different periods. PMID:26314107

  3. Bottom sediments of Lorence Creek Lake, San Antonio, Texas, reflect contaminant trends in an urbanizing watershed

    USGS Publications Warehouse

    Ging, Patricia B.; Van Metre, P.C.; Callender, Edward

    1999-01-01

    Historical use of pesticides and rapid urbanization have left their mark on the chemistry of bottom sediments in Lorence Creek Lake (fig. 1) in the northern part of San Antonio, Tex. Several metals, organochlorine compounds (pesticides and polychlorinated biphenyls [PCBs]), and polycyclic aromatic hydrocarbons (PAHs) detected in bottom sediments of the lake have temporal trends indicating anthropogenic (human) sources. Lorence Creek Lake is not unique; the same metals and organic compounds are routinely found in lake sediments in urbanizing watersheds (Van Metre and Callender, in press).

  4. Abrupt climate-triggered lake ecosystem changes recorded in late glacial lake sediments in northern Poland

    NASA Astrophysics Data System (ADS)

    Slowinski, M. M.; Zawiska, I.; Ott, F.; Noryskiewicz, A. M.; Apolinarska, K.; Lutynska, M.; Michczynska, D. J.; Brauer, A.; Wulf, S.; Skubala, P.; Blaszkiewicz, M.

    2013-12-01

    The aim of this study was to better understand how local lake ecosystems responded to abrupt climate changes through applying multi-proxy sediment analyses. Therefore, we carried out a detailed and high-resolution case study on the late glacial sediment from the Trzechowskie palaeolake located in the eastern part of the Pomeranian Lakeland, northern Poland. We reconstructed climate induced environmental changes in the paleolake and its catchment using biotic proxies (macrofossils, pollen, cladocera, diatoms, oribatidae mite) and classical geochemical proxies (δ18O, δ13C, loss-on-ignition, CaCO3 content) in combination with high-resolution μ-XRF element core scanning. The core chronology has been established by means of biostratigraphy, AMS 14C-dating on plant macro remains, varve counting in laminated intervals and tephrochronology. The latter was possible by the discovery of the late Allerød Laacher See Tephra for the first time at such eastern location. Biogenic accumulation in the lake started rather late during the lateglacial interstadial at 13903×170 cal yrs BP. The rapid and pronounced cooling at the beginning of the Younger Dryas had a major impact on the lake and its catchment as clearly reflected by both, biotic and geochemical proxies. The depositional environment of the lake abruptly changed from a varved to massive gytjia. The pronounced warming at the demise of Younger Dryas cooling is well-reflected in all environmental indicators but with conspicuous leads and lags reflecting complex responses of lake ecosystems to climate warming. The research was supported by the National Science Centre Poland - NN306085037. This study is a contribution to the Virtual Institute ICLEA (Integrated Climate and Landscape Evolution Analysis) funded by the Helmholtz Association.

  5. The origin and distribution of subbottom sediments in southern Lake Champlain.

    USGS Publications Warehouse

    Freeman-Lynde, R. P.; Hutchinson, D.R.; Folger, D.W.; Wiley, B.H.; Hewett, M.J.

    1980-01-01

    3 units, correlatable with recent Lake Champlain, late-glacial marine Champlain Sea, and proglacial Lake Vermont sediments, have been identified from seismic reflection profiles and 8 piston cores. Lake Vermont deposits are nonfossiliferous and range from thin to absent nearshore and on bedrock highs to more than 126 m thick near Split Rock Point. Champlain Sea sediments contain marine foraminifers and ostracodes and are fairly uniform in thickness (20-30 m). Recent Lake Champlain sediments range in thickness from 0 to 25 m. Average sedimentation rates for Lake Vermont are considerably higher (4-8 cm/yr) than those for the Champlain Sea (0.8-1.2 cm/yr) and Lake Champlain (0.14-0.15 cm/yr). Bedrock, till, and deltaic and alluvial deposits were also identified.- from Authors

  6. 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 ...

  7. ASSESSING WATER QUALITY CHANGES IN THE LAKES OF THE NORTHEASTERN UNITED STATES USING SEDIMENT DIATOMS

    EPA Science Inventory

    Diatom assemblages were selected as indicators of lake condition and to assess historical lake water quality changes in 257 lakes in the northeastern United States. The "top" (surface sediments, present-day) and "bottom" (generally from >30 cm deep, representing historical condit...

  8. 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...

  9. 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.

  10. Ferromagnetic response of a sediment record from Lake Soppensee

    NASA Astrophysics Data System (ADS)

    Kind, J.; García-Rubio, I.; Gehring, A. U.

    2012-12-01

    Environmental magnetism uses the spatial and temporal occurrence of magnetic carriers as diagnostic tools to detect environmental changes. Concentration, composition, grain size, and configuration of magnetite can be indicative of the origin of this magnetic carrier. In order to reconstruct the development of Lake Soppensee (Central Switzerland) since the late Pleistocene, a detailed ferromagnetic resonance (FMR) spectroscopy analysis was applied. FMR is a powerful tool to probe the magnetic properties of ferrimagnetic materials. Sediments from Lake Soppensee were analyzed in order to deduce different processes causing the formation of magnetite and its preservation. Based on the occurrence of magnetite, the sediment record can be subdivided into three stages. The first stage, attributed to the deglaciation contains superparamagnetic (SP) magnetite that is detected by the low-temperature FMR analysis. The simultaneous occurrence of SP magnetite in sediments with predominant hematite is interpreted as magnetite formation in reducing interstitial voids within a prevailing oxic environment. The second stage, assigned to the Bølling/Allerød - Younger Dryas period contains stable single domain (SSD) magnetite in varying concentrations. During the Bølling/Allerød denser vegetation cover led to an increase of organic matter in the depositional environment, which accelerated the microbial activity and the consumption of oxygen and the enhanced formation of SSD magnetite. An opposite trend is found for the cold Younger Dryas period. The third stage during the fairly stable Holocene exhibits the formation of SSD magnetite solely. Even though no drastic climatic changes are documented throughout the Holocene, the magnetite content varies considerably. In sediments with high magnetite content, dispersed magnetite particles and magnetite in chain-like configuration were detected by anisotropy traits inferred from the FMR spectra. This configuration provides clear evidence

  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. 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. PMID:25477865

  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 Central

    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-3d-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. PMID:25477865

  18. The magnetic susceptibility measurements of turbidity current sediments from Fuxian Lake of Yunnan Province and their correlations with earthquakes

    NASA Astrophysics Data System (ADS)

    Li, Jie-Sen; Song, Xue-Liang; Sun, Ying-Lun; Zhang, Zi-Xiong; Song, Yi-De; Liu, Gang

    1999-01-01

    This paper has advanced a new method for determining historical earthquakes. Its object of study is lake sediments. The research method is environmental magnetism represented by susceptibility. The purpose is extracting historical earthquake informations from lake sediments to explore the correlation between the turbidity current sediments initiated by the earthquakes and historical earthquakes round Fuxian Lake.

  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. Reconstruction of sediment pathways by variations in sediment characteristics within the Donggi Cona lake catchment, Tibetan Plateau, China

    NASA Astrophysics Data System (ADS)

    Ijmker, J.; Stauch, G.; Wünnemann, B.; Hartmann, K.; Diekmann, B.; Dietze, E.; Opitz, S.; Lehmkuhl, F.

    2009-04-01

    The Chinese Loess Plateau has been described in literature extensively and the provenance of the loess has been studied by many authors. The often bimodal grain-size distribution of Chinese loess points to sediment transport based on two transport processes, and the sand seas in the interior of China seem to be a possible source for the large amounts of loess. However, only few studies focus on aeolian deposits on the Tibetan Plateau. The aeolian sediments on the Tibetan Plateau are coarse compared to their Chinese counterparts. This suggests that the sediments are deposited closer to their source areas. This study focuses on the provenance of terrestrial (aeolian and fluvial) sediments in the Donggi Cona lake catchment. The sediments are studied after grain size using a laser counter, and after their chemical composition using X-ray analysis (Sb, Sn, Cd, Ag, Sr, Rb, Pb, Se, As, Hg, Zn, Cu, Ni, Co, Fe, Mn, Cr, V, Ti, Sc, Ca and K), laboratory analysis (Ca) and elemental analysis (C, N and S). Based on these data, the sediment pathways in the catchment will be reconstructed. Second aim is to find out if the sediments originate from local sources (in-catchment), regional sources or if the sediments are transported over longer distances. Possible in-catchment sediment source areas are the dry former lake bed and alluvial fan sediments. More distal sources could be the sand seas on the northern side of the Tibetan Plateau in China. Dating of the sediments can give an indication of the periods of (enhanced) aeolian transport on the Tibetan Plateau. Reconstruction of the sediment pathways within the catchment can be problematic, because the sediment records are short (meters, compared to hundreds of meters in central China) and the sediments are often mixed due to slope processes. Nevertheless, some deposits show several periods of soil formation that point to changing aeolian transport conditions. Future research will focus on the changing sediment pathways during time

  1. 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

  2. Sinking of volcanic ash in uncompacted sediment in williams lake, washington.

    PubMed

    Anderson, R Y; Nuhfer, E B; Dean, W E

    1984-08-01

    Volcanic ash from the eruption of Mount St. Helens on 18 May 1980 fell into Williams Lake in eastern Washington and was temporarily suspended at the sediment-water interface. After several months of compaction, the ash layer broke up and sank into lower density uncompacted lake sediment. Stratigraphic time displacements of several hundred years and a failure to recognize discontinuous ash layers in sediment cores are possible consequences of this process. PMID:17750852

  3. 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.

  4. FLOCCULATION OF FINE-GRAINED LAKE SEDIMENTS DUE TO A UNIFORM SHEAR STRESS

    EPA Science Inventory

    Experiments were performed to investigate the effects of fluid shear on the flocculation of fine-grained lake sediments in fresh water. In these experiments, a Couette viscometer was used to apply a uniform shear stress to a sediment suspension. he sediments were from the Detroit...

  5. 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.

  6. Wind influence on the course of sedimentation processes of the laminated lacustrine sediments of Lake Czechowskie

    NASA Astrophysics Data System (ADS)

    Wiśniewska, Daria; Kramkowski, Mateusz; Tyszkowski, Sebastian

    2016-04-01

    The studies of the laminated lacustrine sediments play a very important role in the analysis of climate change. They provide valuable information related to the response of the ecosystem to changes in the environment. The condition for the development of the annual lamination is calm sedimentation, which can be compromised by the movement of water caused by waving. The depth to which this movement affects depends on the shape of the lake basin as well as the velocity and direction of the wind. During the study of sedimentary processes of laminated deposits in Lake Czechowskie (Tuchola Forest, North Poland, 53°52'N, 18°14' E, 108 m asl), the following question arose: How strong was the influence of the wind on the processes of lacustrine sedimentation? The key in getting the answers was the use of GIS techniques. Lake Czechowskie has an area of 76.6 hectares; it has two deeps separated by a threshold: a deeper one of 33 m (maximum depth of the basin) in the central-eastern part, and a shallower of 13 m in the western part. The speed of movement of water that is able to move sediment from the bottom of the lake, called the orbital wave velocity, is the basis for the designation of areas where re-suspension takes place. To calculate the wave parameters, the process of mixing, as well as the designation of re-suspension zones, the tool-script Wave Model (Rohweder et al. 2008) in the program ArsGIS 10.1 was used. The input data were wind direction and velocity from the meteorological station of Wirty about 15 km away, bathymetric data from acoustic profiling, and the Maximum Orbital Wave Velocity. The elements taken into account include maximum wind velocity of the multi-year 1996-2013, with particular emphasis on hurricanes Ksawery (December 2013) and Yoda (November 2011), during which wind velocity exceeded 120 km/h. In addition, maximum wind velocity ever recorded in the Polish Lowlands was considered. On the basis of the modelling, the authors delimited the areas

  7. The geomorphic and paleoenvironmental record in the sediments of Atlin Lake, northern British Columbia

    NASA Astrophysics Data System (ADS)

    Gilbert, Robert; Desloges, Joseph R.; Lamoureux, Scott F.; Serink, Andrea; Hodder, Kyle R.

    2006-09-01

    Atlin Lake in northern British Columbia and southern Yukon Territory is the largest natural lake in the North American Cordillera (791 km 2). Inflow from the Juneau Ice Field delivers large volumes of sediment to the proximal basins of Willison Bay and Llewellyn Inlet. Sediment is distributed by interflow and underflow through these basins. Based on acoustic data, each of these basins contain Holocene deposits about 120 m thick, representing mean annual accumulation since deglaciation of more than 1 cm/a. Cores confirm this, except that the formation of a small lake at the toe of Llewellyn Glacier during about the past 50 years is trapping sediment and has reduced accumulation in Llewellyn Inlet by an order of magnitude. Sills separate these basins from the main body of Atlin Lake and Torres Channel where accumulation is much less, averaging about 1-4 mm/a during the history of the lake. Late Pleistocene glacilacustrine sediment occurs as a thin, patchy deposit and is overlain by up to 10 m of Holocene lacustrine deposits. Unlike other large lakes in the Cordillera with thick late Pleistocene deposits indicating large volumes of sediment contributed by glaciers in the lakes and their basins, the pattern in Atlin Lake documents rapid retreat of glaciers from the lake and much of the drainage basin.

  8. Role of sediments in controlling the chemistry of subalpine lakes in the Sierra Nevada, California. Final report

    SciTech Connect

    Amundson, R.G.; Harte, J.; Michaels, H.; Pendall, E.

    1988-12-01

    The importance of sediments in buffering lake water from acidic deposition was assessed by using a diffusion based approach to calculate the flux of alkalinity, and other chemical constituents, from sediments to lake water in three subalpine Sierran lakes. The approach requires the measurement or estimation of temperature, concentration gradients, deposition velocities, diffusion coefficients, porosity, and tortuosity within the sediments and their pore waters. During periods when water is rapidly moving through the lakes, the sediments have little influence on water chemistry. However, during periods of the year when inflows are minimal, sediments exert a greater control on the lake's water.

  9. 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. PMID:27420167

  10. Quantitative spatiotemporal characterization of methane venting from lake sediments

    NASA Astrophysics Data System (ADS)

    Scandella, B.; Pillsbury, L.; Weber, T.; Ruppel, C. D.; Hemond, H.; Juanes, R.

    2014-12-01

    Methane is a potent greenhouse gas, and the production and emission of methane from sediments in inland waters and shallow oceans both contributes to and may be exacerbated by climate change. In some of these shallow-water settings, methane fluxes are often controlled by episodic free-gas venting. The fraction of the methane released from the sediments that bypasses dissolution in the water column and reaches the atmosphere impacts the magnitude of the climate forcing, and this fraction depends critically on the mode and spatiotemporal characteristics of the bubble releases. The spacing and persistence of the gas vents may be determined by the heterogeneity of the methane source, but within regions of uniform methanogenesis they arise from the competition between mechanisms driving lateral and vertical transport of methane in the sediments. Here, we present measurements of the spacing, persistence and variability in intensity of methane vents within a wide area of lake sediments (~400 m2) and over a multi-month period. The measurements were made using a fixed-location Imagenex DeltaT 837B multibeam sonar, which was calibrated to quantify gas fluxes with unprecedented spatial and temporal resolution (~0.5 m, 6 Hz). Drops in hydrostatic pressure were a characteristic trigger for the sonar-detected ebullition events, and the episodicity of the fluxes is reproduced with a mechanistic numerical model of methane venting through dynamic conduits that dilate in response to hydrostatic unloading. The spatial characteristics of the sonar-detected vents inform conceptual and mathematical models of methane transport and release from deformable sediments, as well as the uncertainty associated with upscaling. Taken together, these results point towards a better understanding of the microscale processes controlling methane venting from deformable sediments, as well as their impact on large-scale methane fluxes from shallow-water bodies. Figure: Top: time series of daily sonar

  11. 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.

  12. Possible recording of the Mono Lake Excursion in cored sediment from Clear Lake, California

    NASA Astrophysics Data System (ADS)

    Liddicoat, Joseph; Verosub, Kenneth

    2010-05-01

    We report the possible recording of the Mono Lake Excursion (MLE) in cored sediment from Clear Lake, CA. The locality (39.0˚N, 237.3˚E) is about 120 km north of San Francisco, CA, and 320 km northwest of the Mono Basin, CA, where the MLE first was discovered in North America (Denham and Cox, 1971). The field behaviour at Clear Lake that might be the MLE is recorded in clay and peaty clay about 50 cm below the top of the lowermost 80-cm core slug of a 21.6-m core. The coring was done by the wire-line method (Sims and Rymer, 1975) and the samples (rectangular solids 21 mm on a side and 15 mm high) were measured in a cryogenic magnetometer after demagnetization in an alternating field to 35 milliTesla (Verosub, 1977). The continuously-spaced samples record negative inclination of nearly 20˚ and northerly declination when unnormalized relative field intensity was reduced by an order of magnitude from the mean value. Those palaeomagnetic directions are followed immediately by positive inclination to about 50˚ and easterly declination of about 60˚ when the field intensity is at a relative high. That pattern of behaviour is recorded at three localities (Wilson Creek, Mill Creek, and Warm Springs) in the Mono Basin at the MLE (Liddicoat and Coe, 1979; Liddicoat, 1992). A path of the Virtual Geomagnetic Poles (VGPs) at Clear Lake form a clockwise-trending loop that is centered at 65˚N, 20˚E in the hemisphere away from the locality. The VGP that is farthest from the North Geographic Pole is at 29.3˚N, 337.1˚E, which is close to the path formed by the VGPs in the older portion of the MLE (Liddicoat and Coe, 1979; Liddicoat, 1992). The age of the sediment recording the anomalous palaeomagnetic directions in Clear Lake is about 30,000 years B.P. (Verosub, 1977). That age was determined from six (uncalibrated) radiocarbon dates, three of which are from near the base of the core (Sims and Rymer, 1975) where there are the anomalous palaeomagnetic directions, and linear

  13. Mobility and sulfidization of heavy metals in sediments of a shallow eutrophic lake, Lake Taihu, China.

    PubMed

    Huo, Shouliang; Zhang, Jingtian; Yeager, Kevin M; Xi, Beidou; Qin, Yanwen; He, Zhuoshi; Wu, Fengchang

    2015-05-01

    The technique of DGT (diffusive gradients in thin films) using three diffusive gel thicknesses was applied to estimate the mobility and bioavailability of heavy metals in sediments and porewater of Lake Taihu, China. The DGT results showed significantly positive correlations between Co, Pb, Cd and Mn, and Ni and Fe concentrations in porewater. Cu and Zn showed a significantly negative correlation with Mn, due to Cu combination with carbonates and Zn derived from agricultural pollution, respectively. The rank order of average concentrations of Co, Ni and Cd at each station was DGT1.92>DGT0.78>DGT0.39, suggesting stronger resupply from sediments to porewater when using thicker diffusive gels. Comparing centrifugation and DGT measurements, Co, Ni and Cd are highly labile; Mn and Fe are moderately labile; and Cu, Zn and Pb are slightly labile. The variations of AVS concentrations in sediment cores indicate that metal sulfides in deeper layers are easily diffused into surface sediments. PMID:25968252

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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)

  20. Stable carbon and nitrogen isotopes and amino acids in Holocene sediments of Lake Lonar, central India

    NASA Astrophysics Data System (ADS)

    Menzel, Philip; Gaye, Birgit; Wiesner, Martin; Basavaiah, Nathani; Prasad, Sushma; Stebich, Martina; Anoop, Ambili; Riedel, Nils

    2013-04-01

    Investigations on surface sediments and a sediment core from Lake Lonar in central India were carried out within the framework of the HIMPAC (Himalaya: Modern and Past Climate) programme. The aim was to understand recent productivity, sedimentation, and degradation processes and to reconstruct variations in Holocene lake conditions on the basis of biogeochemical analysis on a 10 m long sediment core retrieved from the centre of Lake Lonar. Located in India's core monsoon zone, Lake Lonar offers valuable information about the climate development of the whole region. The lake is situated at the floor of a meteorite impact structure on the Deccan plateau basalt. The modern lake is characterised by brackish water, high alkalinity, severe eutrophication, and bottom water anoxia. The lake is about 6 m deep and fed by rainfall during the SW monsoon season and three perennial streams. Since no out-flowing stream is present and no seepage loss occurs, the lake level is highly sensitive to the balance of precipitation and evaporation. Here we present C/N, carbon and nitrogen isotope, and amino acid data of bulk organic matter from modern lake and Holocene core sediments. Modern conditions are mainly related to human activity which started to have persistent influence on the biological and chemical lake properties at ~1200 cal a BP. The distribution of δ13C in the modern sediments is driven by the ratio between terrestrial and aquatic organic matter, while δ15N seems to be influenced by redox conditions at the sediment-water-interface with elevated values at shallow oxic stations. Differences in the amino acid assemblages of oxic and anoxic surface sediment samples were used to calculate an Ox/Anox ratio indicating the redox conditions during organic matter degradation. The onset of the monsoon reconstructed from the sediment core occurred at ca. 11450 cal a BP. The early Holocene core sediments are characterised by low sedimentation rate, low aquatic productivity, and

  1. Can ipids in lake sediments help to reconstruct changes in methane availability and methane fluxes in boreal and temperate lakes?

    NASA Astrophysics Data System (ADS)

    Stoetter, T.; van Hardenbroek, M.; Rinta, P.; Schilder, J.; Schubert, C. J.; Heiri, O.

    2013-12-01

    Methane (CH4) is a major greenhouse gas and lakes are an important but poorly studied source of CH4 to the atmosphere. Lipid analysis was used before to identify and quantify CH4 oxidizing bacteria (MOB), giving insight into CH4 oxidation and production in lakes. However, few studies are available that examine how closely the distribution and the carbon isotopic signature (δ13C) of lipids are related to CH4 concentrations and fluxes in different lake ecosystems. In a multi-lake survey we quantified the relationship between lipids, mainly fatty acids (FAs), and CH4 concentrations or fluxes, with the aim of assessing whether FA analysis of lake sediment samples can provide information on past CH4 abundance and production in lakes. The study sites include small lakes in Sweden, Finland, the Netherlands, and Switzerland. Surface sediments collected in the deepest point of the lakes were examined using gas chromatography with flame ionization for determining FA concentrations, gas chromatography mass spectrometry (GC-MS) for identification of individual FAs, and isotope ratio mass spectrometry (IRMS) for determining compound specific δ13C values. Since CH4 is significantly more depleted in 13C than other carbon sources, δ13C is a good tracer for CH4 related processes. The analysis of the acid fraction in the sediments showed that mainly three FAs, identified as C16:1ω7, C16:1ω5 and C18:1ω7, were more depleted in 13C than the others, suggesting that they may originate from MOB. Comparison with literature sources indicated that these FAs are produced by MOB, however, not exclusively. The relative abundance of these depleted FAs showed clear relations to CH4 parameters. For example, increasing abundances were observed with increasing CH4 concentrations in the sediment or with increasing CH4 flux measured at the lake surface. An explanation for these relations would be an increase in MOB biomass with increasing CH4 availability, as they use CH4 as energy and carbon

  2. Hydrocarbons in Lake Washington sediments. A 25-year retrospective in an urban lake.

    PubMed

    Wakeham, Stuart G; Forrest, James; Masiello, Caroline A; Gélinas, Yves; Alexander, Clark R; Leavitt, Peter R

    2004-01-15

    Aliphatic and polycyclic aromatic hydrocarbon and stable and radiocarbon isotope distributions are compared for dated cores from the 1970s and 2000 for a 25-year retrospective in Lake Washington, Seattle, WA (USA). Contamination of Lake Washington sediments by petrogenic aliphatic hydrocarbons and pyrolytic polycyclic aromatic hydrocarbons via atmospheric deposition and stormwater runoff peaked between the 1950s and 1970s and has since decreased as stormwater inputs have been reduced. Radiocarbon signatures (delta14C, per 1000) of total organic carbon decrease (increased "age") in the depth interval of highest hydrocarbon concentration. Graphitic black carbon in the year 2000 core showed a historical profile similar to that of the PAH; however high background sediments deposited before the founding of Seattle indicates a considerable nonindustrial component derived from weathering in the watershed. Unlike hydrocarbon contamination, input of terrestrial organic matter (tracked by long-chain fatty alcohols) has increased throughout the late 20th century, documenting a shift in pollutant sources away from hydrocarbons and toward anthropogenic erosion of the region's soils. PMID:14750717

  3. Bidirectional sulfate diffusion in saline-lake sediments: Evidence from Devils Lake, northeast North Dakota

    USGS Publications Warehouse

    Komor, S.C.

    1992-01-01

    Chemical and isotopic gradients in pore water in Devils Lake indicate that maximum rates of sulfate reduction occur between 1 and 3 cm depth in the bottom sediments. Dissolved sulfate diffuses into the sulfate-reduction zone upward from deeply buried saline pore water at an average rate of 1.4 x 10-5 μmol ⋅ cm-2 ⋅ s-1, and downward from the overlying water column at an average rate of 2.4 x 10-5 μmol ⋅ cm-2 ⋅ s-1. The result is a bidirectional flux of sulfate into the sulfate-reduction zone. Upward-diffusing sulfate provides a ready supply of electron acceptors for sulfate-reducing bacteria even at fairly great depths in the sediments. The abundance of electron acceptors enables sulfate-reducing bacteria to outcompete methanogenic bacteria for organic material and thereby suppress methane production. Suppression of methanogenesis may be widespread in sulfate-rich lakes and wetlands and may limit methane fluxes from these water bodies to the atmosphere.

  4. Microscale characterization of sulfur speciation in lake sediments.

    PubMed

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

    2013-02-01

    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. PMID:23282039

  5. Spatial variability of recent sedimentation in Lake Ohrid (Albania/Macedonia)

    NASA Astrophysics Data System (ADS)

    Vogel, H.; Wessels, M.; Albrecht, C.; Stich, H.-B.; Wagner, B.

    2010-10-01

    Lake Ohrid is likely of Pliocene age and thus commonly referred to as the oldest existing lake in Europe. In this study spatial variability of recent sediment composition is assessed using >50 basin wide distributed surface sediment samples. Analysis of biogeochemical bulk parameters, selected metals, pigment concentrations as well as grain size distributions revealed a significant spatial heterogeneity in surface sediment composition. It implies that sedimentation in Lake Ohrid is controlled by an interaction of multiple natural and anthropogenic factors and processes. Major factors controlling surface sediment composition are related to differences in geological catchment characteristics, anthropogenic land use, and a counterclockwise rotating surface water current. In some instances processes controlling sediment composition also seem to impact distribution patterns of biodiversity, which suggests a common interaction of processes responsible for both patterns.

  6. Matuyama/Brunhes Polarity Transition in Owens Lake, CA, Sediment

    NASA Astrophysics Data System (ADS)

    Liddicoat, Joseph; Kravchinsky, Vadim

    2014-05-01

    The complexity of the Matuyama/Brunhes (M/B) polarity transition is becoming better understood from investigations of volcanic rocks (Coe et al., 2004), loess (Jin et al., 2012; Evans et al., 2011; Kravchinsky, 2013), and marine (Clement and Opdyke, 1982; Hartl and Tauxe, 1996; Macri et al., 2010) and lacustrine (Valet et al., 1988; Sagnotti et al., 2013) sediments. The transition appears to include a brief interval of normal polarity prior to the entry into the Brunhes Normal Chron (Coe et al., 2004; Jin et al., 2012; Evans et al., 2011), and the transition has Virtual Geomagnetic Poles rapidly moving from the Southern Hemisphere to the Northern Hemisphere (Coe et al., 2004; Jin et al., 2012; Evans et al., 2011; Sagnotti et al., 2013). The M/B polarity transition is recorded in exposed Pleistocene lake sediments near Bishop, CA, where the brief interval of normal polarity noted above is present and the change from full reverse to full normal polarity occurs rapidly. The brief interval of normal polarity is recorded at two sites separated laterally by about 150 m and is in single hand samples measured at vertical spacing of 2.0-2.5 cm using six samples per measured level and alternating field demagnetization at 20 mT (Liddicoat, 1993, Table 1 and Fig. 8). The siltstone is unweathered glacial flour from the Sierra Nevada that borders the western side of Owens Valley where the sediments were deposited in Owens Lake. In the siltstone, the majority of the samples have a percentage of about 60 percent where the grain diameter is less than 63 micrometres, and in those samples there is about a five percent fraction when the diameter is two micrometres or less. The Total Inorganic Carbon in most samples is about 0.25 percent (Bergeron, 2013), and magnetite is the dominant carrier of the magnetization (Liddicoat, 1993). The palaeomagnetic directions recording the terminus of the full M/B transition, which occurs before the field intensity is completely recovered, spans no

  7. The preglacial sediment record of Lake Ladoga, Russia - first results from a seismic survey and sediment coring in 2013

    NASA Astrophysics Data System (ADS)

    Melles, Martin; Krastel, Sebastian; Fedorov, Grigory; Subetto, Dmitry A.; Savelieva, Larisa A.; Andreev, Andrej; Wagner, Bernd

    2014-05-01

    The new German-Russian project PLOT (Paleolimnological Transect) aims at investigating the Late Quaternary climatic and environmental history along a more than 6000 km long longitudinal transect crossing northern Eurasia. Special emphasis is put on the preglacial history. For this purpose shallow and deep seismic surveys shall be carried out on five lakes, which potentially host preglacial sediment records, followed by sediment coring based on the results of the seismic campaigns. The well-studied Lake El'gygytgyn represents the eastern-most location of the transect and acts as reference site. Within the scope of a pilot phase for the PLOT project, funded by the German Federal Ministry of Education and Research, we were able to investigate Lake Ladoga, which is located close to St. Petersburg at the western end of the transect. Lake Ladoga is the largest lake in Europe, covering an area of almost 18.000 km2. The modern sedimentation as well as the late glacial and Holocene history of the lake were already studied in detail over the past decades. The older, preglacial lake history, however, is only rudimentary known from a core transect drilled in the southern lake in the 1930th. The cores of up to about 60 m length were only briefly described and are not existing any more. The results from these cores, known from unpublished reports only, suggest the existence of marine sediments of presumably Eemian age, representing a time when Lake Lagoga was part of a precursor of the Baltic Sea, which had a connection via Ladoga and Onega Lakes to the White Sea and further to the Arctic Ocean. In late August/early September 2013 we carried out a seismic survey on Lake Ladoga using a Mini-GI-Gun and a 32-channel seismic streamer. In total, 1500 km of seismic profiles were measured, covering most parts of the lake. The seismic lines typically show acoustically well stratified Holocene muds overlaying rather transparent postglacial varves. These sediment successions can reach

  8. 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.

  9. Tephra Deposits in Lake Mead Miocene Sediments: Characteristics, Chronology, and Sources

    NASA Astrophysics Data System (ADS)

    Dunbar, N. W.; McIntosh, W. C.; Umhoefer, P. J.; Lamb, M. A.; Hickson, T.

    2013-12-01

    The Lake Mead extensional domain, in the east central Basin and Range Province, contains Miocene basin sediments that have undergone complex faulting and deformation. A rich tephra record in the basin sediments provides a chronological and correlation framework that can help understand the depositional and deformational processes during Miocene and post-Miocene time. The tephra layers, up to 10s of cm thick, range from white deposits containing glassy shards to bright green layers in which all original glass has been altered to the zeolite mordenite. The tephra layers range from aphyric to extremely crystal rich. Many appear to be primary ashfall deposits based on depositional geometry, uniform crystal size, and good preservation of glass or relict glass shard structures. However, some layers show evidence of reworking as evidenced by variable crystal size, and the presence of plutonic feldspar and rock fragments. Electron microprobe analyses of preserved glass reveal that compositions of almost all of the tephra layers are high silica rhyolite, typically with FeO and CaO contents of 1wt% or lower. Where present, the glass in the tephra layers is invariably hydrated, consistent with their age, but although the alkali concentrations in the glass are likely to have been modified by the hydration process, other elements, particularly Fe, Ca, Ti, and Cl appear to yield robust concentrations. The compositions of individual layers with respect to these elements are very homogeneous, based on analysis of 20-30 glass shards per sample, and can be used to correlate individual tephra layers between different parts of the sedimentary basin, although a number of layers have very similar compositions. Some higher Fe rhyolites/dacites (up to 4 wt.% FeO) are also observed. Crystal-bearing tephra layers contain some combination of quartz, one or two feldspars (typically a chemically uniform sanidine and a range of plagioclase compositions), biotite, amphibole, and magnetite

  10. Accumulation of Nitrogen in the Pore Water of Anoxic Lake Sediments

    NASA Astrophysics Data System (ADS)

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

    2005-05-01

    The impact of soil runoff nitrogen on the Silver Lake of Iowa was assessed in this study. Currently, the lake cannot support its designated uses as a recreational water body. Extensive algal blooms characterize the lake in late summer, lowering the dissolved oxygen content in water (< 2.0 mg/L). The goal of this study was to map the buildup of nitrogen in the pore water of lake sediments and come up with recommendations for restoration strategies. Sediment cores were taken from 20 sites along 5 transects in the lake. In the top 5 cm of the sediments, the pore water nitrogen ranges between 1.8 and 733.1 micro-gm of nitrate per gm of sediments. The average concentration is 94 micro-g/gm. Vertically, nitrate concentrations were measured at 90 micro-g/gm at 0-10 cm, 95 micro-g/gm at 10-20 cm, and 19 micro-g/gm at 20-30 cm. The sharp decline in nitrate below the 20 cm depth in the sediment is attributed to biochemical reduction of nitrate through denitrification in relatively older, much anoxic sediments. The above results indicate that sediments in Silver Lake are heavily contaminated with N trapped in the pore water. The primary sources of N are the surrounding croplands and an active hog lot on the southeastern lakeshore. The average rate of sedimentation in the lake has been 1 cm/year in the last 32 years. Upon sedimentation, the pore water N is slowly released to the lake water, thereby dramatically limiting the lake's capability to process incoming nutrients. The mass distribution of N in the lake was estimated as 3.66 x 103 kg (65%) in bottom sediments, 172 kg (3%) in suspended particulates, and 1.83 x 103 kg (32%) in the dissolved phase. Some of the recommendations made through this study include dredging the top 25 cm of lake sediments, applying buffer strips along the lake's northern and eastern shorelines, and reducing the application of N and P-based fertilizers.

  11. Analysis of lake-bottom sediment to estimate historical nonpoint-source phosphorus loads

    USGS Publications Warehouse

    Juracek, K.E.

    1998-01-01

    Bottom sediment in Hillsdale Lake, Kansas, was analyzed to estimate the annual load of total phosphorus deposited in the lake from nonpoint sources. Topographic, bathymetric, and sediment-core data were used to estimate the total mass of phosphorus in the lake-bottom sediment. Available streamflow and water-quality data were used to compute the mean annual mass of phosphorus (dissolved plus suspended) exiting the lake. The mean annual load of phosphorus added to the lake from point sources was estimated from previous studies. A simple mass balance then was used to compute the mean annual load of phosphorus from nonpoint sources. The total mass of phosphorus in the lake-bottom sediment was estimated to be 924,000 kg, with a mean annual load of 62,000 kg. The mean annual mass of phosphorus exiting in the lake outflow was estimated to be about 8,000 kg. The mean annual loads of phosphorus added to the lake from point and nonpoint sources were estimated to be 5,000 and 65,000 kg, respectively. Thus, the contribution to the total mean annual phosphorus load in Hillsdale Lake is about 7 percent from point sources and about 93 percent from nonpoint sources.

  12. Heavy metals in bottom sediments of Lake Umbozero in Murmansk Region, Russia.

    PubMed

    Jernström, J; Lehto, J; Dauvalter, V A; Hatakka, A; Leskinen, A; Paatero, J

    2010-02-01

    Sediment cores collected from different locations of Lake Umbozero were studied with respect to concentration and mobility of trace and heavy metals Co, Cu, Fe, Mn, Ni, Pb, U, and Zn. Lake Umbozero is the second largest lake in the Murmansk Region and subjected to contamination by air-borne emissions and river transportation from the nearby metallurgical and mining industries. Unlike its neighboring, more industry-prone Lake Imandra, Lake Umbozero is relatively unexplored with respect to its state of pollution. In our study, metal distribution in sediments was found to vary with respect to the cores, although in general the concentrations were at the same level throughout the lake indicating uniform horizontal distribution of metals. When compared to Lake Imandra, the concentrations of most of the metals studied were significantly lower and represented the levels in sediments measured in lakes of Kola Peninsula located further off from industrial pollutant sources. An exception was Pb the concentration of which was at the same level as in Lake Imandra, probably due to long-distance transport. Sediment layers were subjected to four-step sequential extraction procedure to reveal the metal distribution in soluble, exchangeable, acid-soluble, and residual fractions. Indicative of their potential higher lability, Mn, U, and Zn were generally found in exchangeable fraction; as also Mn and U extensively in the acid-soluble fraction. PMID:19184485

  13. Distribution characteristics of organic phosphorus in sediments from Lake Hulun, China.

    PubMed

    Lü, Changwei; He, Jiang; Zhou, Bin; Vogt, Rolf D; Guan, Rui; Wang, Weiying; Zuo, Le; Yan, Daohao

    2015-10-01

    The amount of organic phosphorus (OP) and its distribution among different pools in lake sediments depend on biotic and abiotic processes driving OP fractionation. The key abiotic factors governing these transformation processes between different OP fractions in sediments were studied on the basis of distribution characteristics of OP pools in sediments from Lake Hulun (HLH). The results showed the order of the size of OP pools in the surface sediments from Lake Hulun to be: Re-OP (residual OP) ≫ FAOP (fulvic acid fraction) ≥ HCl-OP (OP extracted by HCl) > HAOP (humic acid fraction) ≫ LOP (labile OP); lower concentrations of LOP were found in lake surface sediments with high pH (pH > 9) of lake overlying water indicating a governing role of pH in LOP degradation in an aquatic environment. The pattern of total OP (TOP) spatial distribution showed an obvious decreasing trend from the west to the east lake districts in surface sediments from HLH, which was attributed to the inputs of dust and dry grass driven by the prevailing wind and the finer grain size in the west lake districts. However, the spatial distribution pattern of dissolved OP (DOP) in overlying water, which presented different trends with TOP and total organic carbon (TOC) in surface sediments, indicated that the biological factors and terrestrial inputs showed a joint influence on DOP distribution in HLH. The higher levels of Re-OP and lower levels of HCl-OP observed in HLH may reveal that calcium ions and their minerals were the key governing factors of OP fractionation in sediments from HLH. This work revealed the main abiotic process or mechanism driving OP fractionation in the aquatic environment helping to understand the geochemical information archived in OP pools in lake sediments. PMID:26395387

  14. Chemical composition of lake sediments along a pollution gradient in a Subarctic watercourse.

    PubMed

    Dauvalter, Vladimir; Kashulin, Nikolay; Sandimirov, Sergey; Terentjev, Petr; Denisov, Dmitry; Amundsen, Per-Arne

    2011-01-01

    Sediment cores were collected from seven lakes in the Subarctic Pasvik watercourse, polluted by sewage waters and air emissions from the Pechenganickel Metallurgical Company, in order to study chemical composition and estimate the intensity of pollution by taking into account background concentration of elements and the vertical and spatial distribution of their contents in cores and surficial layers of sediments. Sediment samples were analysed by atomic-absorption spectrophotometry for 18 elements (Ni, Cu, Co, Zn, Cd, Pb, Hg, As, Cr, Sr, Mn, Fe, Ca, Mg, Na, K, Al, P). Maximum concentrations of all investigated heavy metals (Ni, Cu, Co, Zn, Cd, Pb, Hg, As) were found in the surficial sediment layers of Lake Kuetsjarvi situated directly below the metallurgic smelters. Decreased contents of heavy metals were observed in surficial sediment layers further downstream in the Pasvik watercourse, although pollution remained rather high. Considerable increase in the contents of the heavy metals emitted into the atmosphere in significant amounts by the Pechenganickel Company (Ni, Cu, Co, Zn), was not observed in surficial sediment layers of lakes upstream in the watercourse polluted only by air contamination and household sewage, but substantial increase of the concentrations of chalcophile elements (Pb, Cd, Hg, As) was revealed. The increase in P contents towards the sediment surface in some lakes may suggest a development of eutrophication processes. Our studies reveal that the metallurgic processing of the Pechenganickel Company has resulted in comprehensive heavy metal pollution and contaminations of lakes sediments in the Inari-Pasvik watercourse. The pollution impact on the sediments is most severe in Lake Kuetsjarvi in the vicinity of the smelters, intermediate in lake localities in the main watercourse downstream the metallurgic enterprises and least in lake localities in the upstream part of the watercourse. PMID:21847792

  15. Lake ecosystem response to rapid lateglacial climate changes in lake sediments from northern Poland

    NASA Astrophysics Data System (ADS)

    Słowiński, Michał; Zawiska, Izabela; Ott, Florian; Noryśkiewicz, Agnieszka M.; Apolinarska, Karina; Lutyńska, Monika; Michczyńska, Danuta J.; Brauer, Achim; Wulf, Sabine; Skubała, Piotr; Błaszkiewicz, Mirosław

    2013-04-01

    During the Late Glacial Period environment changes were triggered by climatic oscillations which in turn controlled processes like, for example, permafrost thawing, vegetation development and ground water circulation. These environmental changes are ideally recorded in lake sediments and thus can be reconstructed applying a multi-poxy approach. Here, we present the results from the Trzechowskie paleolake, located in the northern Polish lowlands (eastern part of the Pomeranian Lakeland). The site is situated on the outwash plain of the Wda River, which was formed during the Pomeranian phase of the Vistulian glaciation ca 16,000 14C yrs BP. The depression of the Trzechowskie lake basin formed after melting of a buried ice block during the Allerød (13903±170 cal yrs BP). We reconstructed environmental changes in the Trzechowskie paleolake and its catchment using biotic proxies (macrofossils, pollen, cladocera, diatoms, oribatidae mite) and geochemical proxies (δ18O, δ13C, loss-on-ignition (LOI), CaCO3 content). In addition, we carried out µ-XRF element core scanning. The chronology has been established by means of biostratigraphyAMS14C dating on plant macro remains, varve counting in laminated intervals and the late Allerød Laacher See Tephra isochrone. Our results showed that biogenic accumulation in the lake started during the Bølling. Development of coniferous forest during the Allerød with dominance of Pinus sylvestris lead to leaching of carbonates in the catchment due to low pH increasing the flux of Ca ions into the lake. In consequence calcite precipitating in the lake increased as evidences by increasing CaCO3 contents. Both biotic and physical proxies clearly reflect the rapid decrease in productivity at the onset of the Younger Dryas. We compare the data from the Trzechowskie paleolake with the Meerfelder Maar and Rehwiese lake records based on tephrochronological synchronization using the Laacher See Tephra. This study is a contribution to the

  16. Laboratory-determined Phosphorus Flux from Lake Sediments as a Measure of Internal Phosphorus Loading

    PubMed Central

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

    2014-01-01

    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. PMID:24637715

  17. Flood and sediment dynamics in Lake Mondsee: insights from a hydro-sedimentary monitoring

    NASA Astrophysics Data System (ADS)

    Kämpf, Lucas; Mueller, Philip; Swierczynski, Tina; Güntner, Andreas; Merz, Bruno; Brauer, Achim

    2014-05-01

    Detrital layers in lake sediments are increasingly exploited to establish continuous long flood chronologies. The annually laminated sediments of Lake Mondsee (486 m a.s.l., Upper Austria) provide a seasonally resolved flood layer record over the past 7000 years. However, detailed comparison of sediment and instrumental flood data revealed a partial mismatch emphasizing the need for a better understanding of hydrological and sedimentological processes leading to the formation of flood-triggered sediment layers. For this purpose, a monitoring network was set up at Lake Mondsee recording run-off and suspended sediment concentration at the outlet of the main tributary, the Griesler Ache River, and collecting sediment within the lake at three-day-time intervals by sediment traps, one located 0.9 km off the main inflow (water depth: 55 m) and one in the deepest part of the lake (61 m) in a more distal position at a distance of 2.8 km. Our monitoring data cover a period of 30 months from January 2011 to July 2013. The mean sediment flux in Lake Mondsee yields 4 g/(sqm*d) and exhibits (I) a pronounced seasonal variability and (II) a succession of 30 occasional peaks in mainly detrital sediment flux reaching values of up to 758 g/(sqm*d) at the proximal trap and 59 g/(sqm*d) at the distal trap. The comparison with runoff data revealed (I) coincidence of 83% of the sediment flux peaks with elevated runoff events spanning from 10 to 110 cbm/s, (II) empiric flood thresholds for triggering significant sediment influx in the proximal (20 cbm/s) and distal lake basin (30 cbm/s) and (III) a variable spatial sediment distribution. The latter is mainly due to the role of (i) flood duration, (ii) the existence of a thermocline in summer leading to favoured sediment transport in the upper water column and (iii) local sediment sources which episodically contribute additional detrital material. Monitoring floods of very different intensity and seasonal occurrence shows a complex

  18. Sediment Resuspension Caused by Wind-Induced Current in Lake Izunuma

    NASA Astrophysics Data System (ADS)

    Umeda, Makoto; Betto, Yusuke; Shindo, Kentaro

    Lake Izunuma is a shallow lake located in the north part of Miyagi prefecture, whose water quality has been extremely deteriorated. One of the phenomena that influence the water quality is behavior of sediment that has accumulated on the bottom of the lake. In this study, field measurements were conducted during the windy season of winter, when resuspension of sediment is most active. Turbidity, water velocity, wave height were continuously measured in the lake for about three weeks. From the observed data, wave height and velocity oscillation had much to do with increase in turbidity. This fact indicated that resuspension of sediment was mostly caused by wind wave turbulence, which was affected by not only wind speed but also fetch determined from the planar shape of the lake and wind direction. Considering this effect, history and distribution of turbidity during the strong wind event was reproduced with a hydrodynamic numerical modeling.

  19. Sediment Microbial Community Structure and Mercury Methylation in Mercury-Polluted Clear Lake, California

    PubMed Central

    Macalady, J. L.; Mack, E. E.; Nelson, D. C.; Scow, K. M.

    2000-01-01

    Spatial and temporal variations in sediment microbial community structure in a eutrophic lake polluted with inorganic mercury were identified using polar lipid fatty acid (PLFA) analysis. Microbial community structure was strongly related to mercury methylation potential, sediment organic carbon content, and lake location. Pore water sulfate, total mercury concentrations, and organic matter C/N ratios showed no relationships with microbial community structure. Seasonal changes and changes potentially attributable to temperature regulation of bacterial membranes were detectable but were less important influences on sediment PLFA composition than were differences due to lake sampling location. Analysis of biomarker PLFAs characteristic of Desulfobacter and Desulfovibrio groups of sulfate-reducing bacteria suggests that Desulfobacter-like organisms are important mercury methylators in the sediments, especially in the Lower Arm of Clear Lake. PMID:10742230

  20. Historical change in lake sedimentation in Lake Takkobu, Kushiro Mire, northern Japan over the last 300 years

    NASA Astrophysics Data System (ADS)

    Ahn, Young Sang; Mizugaki, Shigeru; Nakamura, Futoshi; Nakamura, Yugo

    2006-08-01

    Environmental degradation, including shallowing, deterioration of aquatic habitat and water pollution, has arisen from the inflow of fine sediment to Lake Takkobu in northern Japan. The lake has experienced gradual environmental degradation due to agricultural development, which has introduced both fine sediment and sediment-associated nutrients into the lake. We have reconstructed the history of sediment yield to Lake Takkobu in Kushiro Mire over the last 300 years and have examined trends with reference to land-use development. Fifteen lake sediment core samples were obtained, and various physical variables of lake sediments were analyzed and dated using 137Cs and tephrochronology. The physical variables showed that all points contained mainly silt, except for two points close to the river mouths, where the mean diameter was < 35 μm. The peaks were defined as a "signal" when the physical variables were synchronous in a profile. These were created by floods and engineering works constructing drainage systems. The signal of canal construction in 1898 was detected in all core points. Lake Takkobu core samples contained two tephra layers. From the refractive indices of dehydrated glasses, the lower tephra layer was identified as Ko-c2 (1694) and the upper tephra layer as Ta-a (1739). A clear peak in the 137Cs concentration was detected at all the sampling points, except for the site close to the Takkobu River. This site showed two peaks in the 137Cs concentration, which was attributed to perturbation from flood events and a drainage project. The maximum 137Cs concentration was identified as the sediment surface from 1963, enveloped by the 1962 and 1964 signals. The sediment yield averaged over the last 300 years for Lake Takkobu was reconstructed for four periods using the signal, tephra and 137Cs as marker layers. The sediment yield under the natural erosion condition for the first two periods was 226 tons/year from 1694 to 1739 and 196 tons/year from 1739 to 1898

  1. 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.

  2. Comparative microfacies studies on annually laminated lake sediments from lakes of different sizes in northern Germany- Palaeolimnological implications

    NASA Astrophysics Data System (ADS)

    Dreibrodt, Stefan

    2016-04-01

    The composition of annually laminated lake sediments was studied in thin sections. Investigations on recently deposited warves and microfacies indicators known from the literature were used to infer about limnological processes explaining a given mid-Holocene warve sequence. Geochemical analyses were carried out for supplemental information (e.g. aeration of the hypolimnion). The sequences of sediments deposited from ca. 4.900 to 6.900 cal BC in Lake Belau and Lake Poggensee were compared. According to the abovementioned indicators a reconstruction of the storminess (intensity of circulation), summer temperatures, and severity of winters (NAO stage) was carried out ending up with a graph of relative changes for the studied interval. Since the compared lake systems have considerably different sizes (about a magnitude) abrupt changes in sedimentation detected synchronously in both lakes but differing in shape were interpret as varying responses to climatic anomalies. These anomalies are considered to represent extraordinary cold spells during the summers at ca. 5.900 and 5.300 cal BC. Similarly, a short phase of probably unusual warm winters occurred at ca. 5.350 cal. BC. The example illustrates the potential of comparing lakes systems of different dimensions utilizing different system thresholds that result in varying limnological responses to external triggers.

  3. 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...

  4. Using SWAT to target critical source sediment and phosphorus areas in the Wister Lake Basin, USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wister Lake is located in the San Bois Mountains in southeastern Oklahoma, USA. The reservoir is primarily used as a water supply and flood storage to over 40,000 residents in the area. Due to high levels of phosphorus and sediment, Wister Lake is listed as a high priority basin for the State of Okl...

  5. 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 ...

  6. 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...

  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. 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...

  9. SEDIMENT REWORKING AND TRANSPORT IN EASTERN LAKE SUPERIOR: IN SITU RARE EARTH ELEMENT TRACER STUDIES

    EPA Science Inventory

    A rare earth element (REE) tracer pellet was deployed at the floor of the Ile Parisienne basin of eastern Lake Superior to measure representative sediment reworking and transport processes in the benthic boundary layer of the prnfundal Great Lakes. Samarium oxide, a high neutron-...

  10. EARLY EUTROPHICATION IN THE LOWER GREAT LAKES: NEW EVIDENCE FROM BIOGENIC SILICA IN SEDIMENTS

    EPA Science Inventory

    New evidence from studies of biogenic silica and diatoms in sediment cores indicates that eutrophication in the lower Great Lakes resulted from nutrient enrichment associated with early settlement and forest clearance. Diatom production peaked from 1820 to 1850 in Lake Ontario, a...

  11. 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,...

  12. 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...

  13. Ground-water seepage and sulfur diagenesis in acidified lake sediments

    SciTech Connect

    McIntire, P.E.

    1988-01-01

    Most sulfur diagenesis models predict that porewater SO{sub 4}{sup 2{minus}} concentrations will decrease exponentially with increasing sediment depth and will be lower than that of the overlying water throughout the sediments. Sulfate concentrations below 0.2 mM are common in Lake Anna sediments which receive acid mine drainage; however, sediment porewater containing up to 29 mM SO{sub 4}{sup 2{minus}} is also seen at about 20 cm below the sediment surface in this section of the lake. A decision tree was used to investigate the cause of the high SO{sub 4}{sup 2{minus}} concentrations at depth (HSD) in the sediment. The first hypothesis was that increased ground-water flow through Lake Anna HSD sediments, relative to the non-HSD sediments, increases groundwater advection of SO{sub 4}{sup 2{minus}} or of oxygen which would induce sulfide oxidation. Stations having HSD profiles did not have higher groundwater flow than other sites samples. Alternative explanations for the HSD profiles were that the region in which they occurred had (1) unusual sediment chemical compositions; (2) groundwater seepage containing unusually high sulfate concentrations; or (3) a lateral intrusion of high SO{sub 4}{sup 2{minus}} water from the sulfide mines which supplied SO{sub 4}{sup 2{minus}} to the HSD region before the lake was impounded.

  14. Effects of Drought-Induced Sediment Resuspension on Phosphorus Availability in Lake Powell, Utah

    NASA Astrophysics Data System (ADS)

    Wildman, R. A.; Miller, J.; Hering, J. G.

    2006-12-01

    The damming of a large river creates a lake ecosystem that differs substantially from that of the unaltered river upstream. Unlike a natural lake, this ecosystem is subject to large perturbations resulting from reservoir management decisions. For example, significant change in water surface elevation can lead to resuspension of lakebed sediments in the inflow region of the reservoir and may have important implications for the nutrient dynamics of a reservoir. Impounded by Glen Canyon Dam, Lake Powell is a large, long, and narrow reservoir on the mainstem of the Colorado River in Arizona and Utah. A severe drought in the Rocky Mountains has significantly decreased inflows to the lake. Constant yearly dam releases have led to a precipitous drop in the surface elevation and water storage of Lake Powell, including a record low in April 2005. The incoming Colorado River now cuts through the previously-undisturbed sediment delta. Thus, much of the incoming suspended load may come from the resuspension of deltaic sediments. Since these sediments likely contain phosphorus, this deltaic resuspension could be a major new source of nutrients to the oligotrophic, phosphorus-limited lake ecosystem. To quantify the resuspension and phosphorus concentration in the Lake Powell deltaic sediments, 70 and 100 cm cores were collected from the lakebed and shore sediments of Lake Powell March and May 2006. Cores were collected at six locations along the Colorado River delta in the inflow region of the lake and at three shore locations where the former delta sediments have been exposed. Water and suspended sediment samples were also collected at various depths at the same locations as the lakebed cores. Phosphorus concentration was measured in all samples. Sequential extractions were performed to assess the distribution of phosphorus in the solid phase. Ancillary sediment analyses included organic carbon and particle size measurements. The two sampling events captured different

  15. [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. PMID:19068626

  16. 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??.

  17. Accumulation of polychlorinated biphenyl congeners from Lake Champlain sediments by Mysis relicta

    SciTech Connect

    Lester, D.C.; McIntosh, A. . Vermont Water Resources and Lake Studies Center)

    1994-11-01

    Polychlorinated biphenyl (PCB) levels in lake trout (Salvelinus namaycush) from Lake Champlain often exceed the F.D.A. tolerance level of 2 [mu]g/g (wet weight). Of added concern are recent studies that suggest a relationship between the dioxin-like properties of non-ortho-substituted PCB congeners and impaired lake trout egg hatchability. Dietary accumulation of PCBs is thought to be an important exposure route for fish. The epibenthic freshwater shrimp Mysis relicta is an integral part of the benthic and pelagic food web in lake Champlain and may act as a link between PCBs in sediments and lake trout. Previous investigations have shown that diurnal migrations of mysids enhance the movement and distribution of toxic contaminants, effectively coupling the benthic and pelagic zones. The objective of this research was to examine the role contaminated sediments play in the transfer of PCBs to mysids. Bioaccumulation was assessed by exposing mysids to such sediments in two ways: (a) with organisms screened from sediments; and (b) with organisms in direct contact with sediments. Accumulation of PCBs over the course of the 24-day exposure period was examined on the following days: 0, 3, 6, 12, 21, and 24. Eighty-nine individual PCB congeners were measured in tissue and sediment. Mysids in direct contact with sediments accumulated significantly higher levels of PCBs than did organisms screened from sediments. Mysids accumulated substantial levels of PCBs, suggesting they may play an important part in the transfer of PCBs from sediments into the Lake Champlain food web. It is clear from this research that sediments can play a critical role in the accumulation of PCBs by mysids.

  18. Testing the potential of 10Be in varved sediments from two lakes for solar activity reconstruction

    NASA Astrophysics Data System (ADS)

    Czymzik, Markus; Muscheler, Raimund; Brauer, Achim; Adolphi, Florian; Ott, Florian; Kienel, Ulrike; Dräger, Nadine; Slowinski, Michal; Aldahan, Ala; Possnert, Göran

    2015-04-01

    The potential of 10Be in annually laminated (varved) lake sediments for solar activity reconstruction is, to date, largely unexplored. It is hypothesized that 10Be contents in sediments from well-chosen lakes reflect the solar induced atmospheric production signal. The varved nature of these archives provides the chance to establish solar activity time-series with very high temporal precision. However, so far solar activity reconstruction from 10Be in varved lake sediments is hampered due to a lack of detailed knowledge of the process chain from production in the atmosphere to deposition on the lake floor. Calibrating 10Be time-series from varved lake sediments against complementary proxy records from the same sediment archive as well as instrumental meteorological and solar activity data will allow a process-based understanding of 10Be deposition in these lakes and a quantitative evaluation of their potential for solar activity reconstruction. 10Be concentration and flux time-series at annual resolution were constructed for the period 1983 to 2007 (approx. solar cycles 22 and 23) conducting accelerator mass spectrometry and varve chronology on varved sediments of Lakes Tiefer See and Czechowski, located on an east-west transect at a distance of about 450 km in the lowlands of northern-central Europe. 10Be concentrations vary between 0.9 and 1.8*108atoms/g, with a mean of 1.3*108atoms/g in Lake Tiefer See and between 0.6 and 1.6*108atoms/g, with a mean of 1*108atoms/g in Lake Czechowski. Calculated mean 10Be flux is 2.3*108atoms/cm2/year for Lake Tiefer See and 0.7*108atoms/cm2/year for Lake Czechowski. Calibrating the 10Be time-series against corresponding geochemical μ-XRF profiles, varve thickness and total organic carbon records as well as precipitation data from the nearby stations Schwerin for Lake Tiefer See and Koscierzyna for Lake Czechowski and a neutron monitor record of solar activity suggests (1) a complex interaction of varying processes influencing

  19. Tracking the sediment imprint of floods (in pre-Alpine Lake Mondsee) by a combined catchment and in-lake monitoring system

    NASA Astrophysics Data System (ADS)

    Mueller, Philip; Kämpf, Lucas; Thoss, Heiko; Güntner, Andreas; Merz, Bruno; Brauer, Achim

    2014-05-01

    Lakes form ideal sediment traps in the landscape and continuously record land surface processes including extreme events. During floods, detrital sediment is transported via tributary streams and deposited at the lake floor as discrete layers, intercalated in autochthonous lake sediments. Lacustrine records of detrital layers are increasingly explored as flood archives for pre-instrumental periods. The annually laminated sediments of Lake Mondsee (486 m a.s.l., Upper Austria) contain a flood layer chronology over the past 7000 years with seasonal resolution. The interpretation of lacustrine flood layer records, however, requires detailed understanding of hydro-sedimentary transport and deposition processes of flood-related sediments from the catchment as a source to the lake as a sediment sink. For this purpose, a comprehensive monitoring network was set up in the catchment of Lake Mondsee. Flood and sediment transport related variables like precipitation, runoff and turbidity as a surrogate for suspended sediment concentration (SSC) are monitored at five gauges along the main tributary, the Griesler Ache River. Gauge deployment follows a nested catchment approach ranging from the headwaters to the outlet to the lake. Four monitoring buoys on the lake recording meteorological parameters as well as limno-physical variables (water temperature, turbidity, current velocity) at multiple depths of the water column are used to explore the flood-related sediment dynamics in the lake. To retrieve event-specific data on sediment deposition, two sediment trap chains were deployed, one in a proximal position to the Griesler Ache inflow and another one in a distal position in the deepest part of lake basin where sedimentation is most continuous. All units of the monitoring network collected data during the severe Central European summer flood event in June 2013. Suspended sediment concentrations could be derived from rating curves based on water samples taken automatically for

  20. Subglacial Lake Whillans, West Antarctica; Solute Dynamics and Fluxes to the Ross Sea

    NASA Astrophysics Data System (ADS)

    Skidmore, M. L.; Michaud, A. B.; Achberger, A.; Barbante, C.; Christner, B. C.; Mikucki, J.; Mitchell, A. C.; Priscu, J. C.; Purcell, A. M.; van Gelder, W.; Vick-Majors, T.

    2014-12-01

    Subglacial Lake Whillans is located beneath the Whillans Ice Stream in West Antarctica. The lake is situated beneath 800 m of ice and ~ 70 km upstream of the grounding line where Whillans Ice Stream terminates into the Ross Sea. Subglacial Lake Whillans is a shallow lake and a component of a complex subglacial hydrological system that may resemble a large wetland along the Siple Coast of West Antarctica. Subglacial Lake Whillans drains and refills on a sub-decadal time scale discharging water towards the Ross Sea. Water and sediment samples were recovered from the lake, using clean access drilling technologies, in January, 2013. Isotopic analysis of the lake waters indicates basal meltwater from the ice sheet as the dominant water source. Geochemical analysis of the lake water reveals it is freshwater with mineral weathering as a significant solute source, with a minor contribution from sea water likely from relict marine sediments. Subglacial hydrothermal activity upstream may also contribute solutes. Nutrients N and P are present at micromolar concentrations. Sediment porewaters from shallow cores (~ 40 cm depth) of the subglacial lake sediments indicate increasing solute concentration with depth, with up to ~ five times greater solute concentrations than in the lake water. The waters and sediment contain metabolically active organisms which are likely involved in elemental cycling within the lake system. Here we will discuss solute sources to the lake, solute dynamics within the lake waters and sediment, and the fluxes of solute and nutrients to the Ross Sea and their implications for these marine ecosystems.

  1. 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.

  2. 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.

  3. Spatial and temporal variability in metal bioavailability and toxicity of sediment from Hamilton Harbour, Lake Ontario

    SciTech Connect

    Krantzberg, G. )

    1994-10-01

    Trace metals in sediment from nearshore urban and industrialized centers of the Great Lakes are frequently at concentrations well above geological background values. Total metal content in sediment, however, is a weak predictor of sediment toxicity. This study examined the bioavailability of metals from Hamilton Harbor in Lake Ontario and considered variability in metal forms on a temporal basis. Sediment from regions within Hamilton Harbor is highly contaminated with metals; nevertheless, not all metal-contaminated sites were toxic to test organisms. Most sediment did elicit sublethal and/or lethal responses in bioassay organisms. Metal bioavailability, as measured by weak acid extractions, metal bioaccumulation by fathead minnows, and sediment toxicity, was greater in sediment collected in the fall as compared to sediment collected in the spring. Results of analyses of tissue residues in test organisms and the reduced toxicity observed in sediment collected from some stations in the spring as compared to the fall implicate trace metals and sediment oxygen demand as contributing to sediment toxicity. The suitability for colonization by benthic invertebrates of sediment in some areas of Hamilton Harbor appears to be limited by both contaminants and high sediment oxygen demand. Improving the oxygen regime of the harbor should result in improvements in the benthic invertebrate community directly, by providing a suitable oxygen regime for organisms less tolerant of temporal anoxia, and indirectly by decreasing metal bioavailability, possibly through the co-precipitation of trace metals with iron and manganese hydroxides.

  4. Stratigraphic and Paleomagnetic Study of Glacial Lake Missoula Lacustrine and Flood Sediments

    NASA Astrophysics Data System (ADS)

    Hanson, M. A.; Barendregt, R.; Clague, J. J.; Enkin, R. J.

    2007-12-01

    During the late Wisconsinan, the Purcell Trench lobe of the Cordilleran Ice Sheet advanced south into Idaho where it dammed the Clark Fork River and formed glacial Lake Missoula in western Montana. The lake repeatedly filled and emptied through its dam between about 16,000 and 12,500 14C yr ago. The floodwaters entered glacial Lake Columbia, Washington, and spilled across the plateaux of eastern Washington. Repeated floods excavated the Channeled Scablands and deposited slackwater sediments in several valleys in Washington and in the Willamette Valley in Oregon. Stratigraphic study of the flood and slackwater sediments in Washington and Oregon, and of glacial Lake Missoula sediments near Missoula, Montana, provide evidence for at least 46 glacial Lake Missoula floods. Paleomagnetic analyses were done on oriented samples of (1) glacial Lake Missoula sediments at the Ninemile section and at a section in Missoula (348 samples); (2) interstratified flood and lacustrine sediments at the Manila Creek site in the Sanpoil Valley, Washington (615 samples); and (3) backwater sediments in the Yakima, Walla Walla, and Willamette valleys (813 samples). The sediments record strong and stable magnetic remanence carried by either magnetite or hematite. Magnetic remanence directions of flood beds and of interbedded lacustrine units show secular variation over a time span of hundreds to a few thousands of years, consistent with deposition by many tens of floods separated on average by several decades. Rock magnetic properties of the flood deposits give insight into depositional processes involved and the source of the floodwaters. We are now attempting to date the floods using radiocarbon and optically stimulated luminescence techniques, to correlate the paleomagnetic records between our study sites, which are up to 750 km apart, and to correlate them with well dated paleomagnetic records from Fish Lake, Oregon, and Mono Lake, California.

  5. Recognizing seiche and tsunami effects in lake sediments

    NASA Astrophysics Data System (ADS)

    Marco, Shmuel; Alsop, Ian G.; Katz, Oded; Dray, Yehoshua

    2014-05-01

    The lacustrine 70-15-ka Lisan Formation outcropping around the Dead Sea contains superb examples of slump folds formed in water depths of <100 m. New structural data from individual horizons demonstrate that several of these gravity-driven slumps are coaxially refolded and reworked by folds and thrusts verging both back up and then down the palaeoslope. The uppermost folds are often truncated. A progressive increase in reworking and shearing is developed up through the folded sediment, culminating in an upward-finning breccia layer that is capped by a thin, typically graded horizon of undeformed fine-grained clasts. We interpret this sequence as a seiche-related deformation. Based on the similarity of the structures in the Lisan Formation and on additional supporting observations we interpret zigzag-shaped sand injections in artificial lake deposits on the Eastern Mediterranean shore as evidence for a tsunami, possibly associated with the earthquake of 25 November 1759. If this interpretation is correct it supports the hypothesis that onshore Dead Sea Fault earthquakes can trigger tsunamis in the Mediterranean.

  6. 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

  7. 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...

  8. 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...

  9. 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...

  10. 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.

  11. Occurrence of Atrazine and Related Compounds in Sediments of Upper Great Lakes.

    PubMed

    Guo, Jiehong; Li, Zhuona; Ranasinghe, Prabha; Bonina, Solidea; Hosseini, Soheil; Corcoran, Margaret B; Smalley, Colin; Kaliappan, Rajashankar; Wu, Yan; Chen, Da; Sandy, Andy L; Wang, Yawei; Rockne, Karl J; Sturchio, Neil C; Giesy, John P; Li, An

    2016-07-19

    Surface grab and core sediment samples were collected from Lakes Michigan, Superior, and Huron from 2010 to 2012, and concentrations of herbicides atrazine, simazine, and alachlor, as well as desethylatrazine (DEA), were determined. Concentrations of atrazine in surface grabs ranged from 0.01 to 1.7 ng/g dry weight and are significantly higher in the southern basin of Lake Michigan (latitude <44°) than other parts of the three lakes. The highest concentration of alachlor was found in sediments of Saginaw Bay in Lake Huron. The inventory and net fluxes of these herbicides were found to decline exponentially from the south to the north. The concentration ratio of DEA to atrazine (DEA/ATZ) increased with latitude, suggesting degradation of atrazine to DEA during atmospheric transport. DEA/ATZ also increased with sediment depth in the sediment cores. Diffusion of deposited herbicides from the upper sediment into deeper sediments has occurred, on the basis of the observed patterns of concentrations in dated sediment cores. Concentrations of atrazine in pore water were estimated and were higher than those reported for the bulk waters, suggesting the occurrence of solid-phase deposition of atrazine through the water column and that contaminated sediments act as a source releasing atrazine to the overlying water. PMID:27322944

  12. 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...

  13. Clay Mineral Composition of Sediments in Some Desert Lakes in Nevada, California, and Oregon.

    PubMed

    Droste, J B

    1961-06-16

    X-ray analyses of some Recent desert lacustrine sediments in Nevada, California, and Oregon show that illite and montmorillonite are the most abundant clay minerals and that chlorite and kaolinite are present in subordinate amounts in the sediments of many of the lakes. These clay suites are derived from source rocks. PMID:17738874

  14. 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

  15. 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.

  16. 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.

  17. 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.

  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. PMID:24902065

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

    PubMed

    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

  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. 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.

  3. 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.

  4. 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.

  5. Underflows in Lake Constance - Numerical Modeling, Instrumental Observations and Sediment Data

    NASA Astrophysics Data System (ADS)

    Eder, Magdalena; Wessels, Martin; Dare, Julian

    2014-05-01

    A torrential rain event in the western Alps in August 2005 caused high flood flows in the rivers Alpine Rhine and Bregenzer Ache which are the main tributaries into Lake Constance. The discharge of the Alpine Rhine reached 2200 m³/s, which is little below a centennial flood event. Discharge of the Bregenzer Ache was estimated to 1350 m³/s which statistically occurs every 100 yr but with a 1000 yr frequency in selected smaller tributaries. The high concentration of suspended solids in the fluvial water increased its density and created an underflow with considerable influence on the lake's hydrodynamics and water quality. Consequences within the lake were directly registered by a mooring (equipped with thermistor chain, sediment trap, current meter, oxygen sensor). Spatial data of the path and form of suspended matter cloud within the lake were gathered using echo sounder and probe measurements (turbidity, temperature, salinity). An underflow with a temperature of 14°C flew with 1.4 km/h some 20 km into the lake. Several days after the event, the fluvial sediments were detected as increased turbidity at the drinking water outtakes around the lake. Sediment cores recovered from the lake bottom show the distribution pattern of the sediments while sidescan data give a picture from proximal sediment structures originating from this event. Further, we modelled this underflow using the three dimensional hydrodynamic and water quality model ELCOM-CAEDYM. The suspended solids module of the model accounts for the impact of the sediment load on water density. Settling is considered using Stokes Law, and resuspension can also be included. The simulation of the August 2005 flood event and comparison with measured data impressively showed the ability to reproduce the most important effects of the flood flow on the lake. Comparative simulations with and without consideration of the coriolis effect indicate an influence of the coriolis force on the flow path of the density

  6. Tracking the hydro-climatic signal from lake to sediment: A field study from central Turkey

    NASA Astrophysics Data System (ADS)

    Dean, Jonathan R.; Eastwood, Warren J.; Roberts, Neil; Jones, Matthew D.; Yiğitbaşıoğlu, Hakan; Allcock, Samantha L.; Woodbridge, Jessie; Metcalfe, Sarah E.; Leng, Melanie J.

    2015-10-01

    Palaeo-hydrological interpretations of lake sediment proxies can benefit from a robust understanding of the modern lake environment. In this study, we use Nar Gölü, a non-outlet, monomictic maar lake in central Turkey, as a field site for a natural experiment using observations and measurements over a 17-year monitoring period (1997-2014). We compare lake water and sediment trap data to isotopic, chemical and biotic proxies preserved in its varved sediments. Nar Gölü underwent a 3 m lake-level fall between 2000 and 2010. δ18Olakewater is correlated with this lake-level fall, responding to the change in water balance. Endogenic carbonate is shown to precipitate in isotopic equilibrium with lake water and there is a strong relationship between δ18Olakewater and δ18Ocarbonate, which suggests the water balance signal is accurately recorded in the sediment isotope record. Over the same period, sedimentary diatom assemblages also responded, and conductivity inferred from diatoms showed a rise. Shifts in carbonate mineralogy and elemental chemistry in the sediment record through this decade were also recorded. Intra-annual changes in δ18Olakewater and lake water chemistry are used to demonstrate the seasonal variability of the system and the influence this may have on the interpretation of δ18Ocarbonate. We use these relationships to help interpret the sedimentary record of changing lake hydrology over the last 1725 years. Nar Gölü has provided an opportunity to test critically the chain of connection from present to past, and its sedimentary record offers an archive of decadal- to centennial-scale hydro-climatic change.

  7. 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

  8. Speciation of Al, Fe, and P in recent sediment from three lakes in Maine, USA.

    PubMed

    Norton, Stephen A; Coolidge, Kyle; Amirbahman, Aria; Bouchard, Roy; Kopácek, Jirí; Reinhardt, Raquel

    2008-10-15

    Sequential extraction of sediments [Psenner R, Pucsko R. Die Fraktionierung organischer und anorganischer Phosphorverbindungen von Sedimenten. Arch Hydrobiol/Suppl 1988. 70(1): 111-155.] from short, (210)Pb-dated cores from three lakes in Maine USA demonstrates that sediment P is dominantly associated with the NaOH-extractable fraction (P-NaOH(25)) and less with the bicarbonate-dithionite extractable fraction (P-BD). The ratios (Al-NaOH(25))/(Fe-BD) and (Al-NaOH(25))/(P-NH(4)Cl+P-BD) for upper sediment for two oligo-mesotrophic lakes exceeded 3 and 25, the thresholds for preventing substantial release of P from sediments during hypolimnetic anoxia [Kopácek J, Borovec J, Hejzlar J, Ulrich K-U, Norton SA, Amirbahman A. Aluminum control of phosphorus sorption by lake sediments. Environ Sci Technol 2005a;39:8784-8789.]. Hypolimnetic water chemistry verifies this effect. The third lake, currently eutrophic, has values for the ratios that are below the thresholds and this lake has substantial release of P from recent sediment. The sediment characteristics remain relatively constant over the last 150+ years, indicating that the processes responsible for P retention have operated long before atmospheric acidification of watersheds might have influenced the flux of Al and Fe to the lake. In 2002, the pH of inlets and the lakes was generally between 6 and 8. Input to the lakes had high concentrations of acid-soluble particulate and dissolved Al, Fe, and P, and dissolved Al and Fe complexed with dissolved organic carbon (DOC). Lake water column and outlet Al, Fe, and P were typically 90-95% lower than inlet concentrations over a 12 month period. Photo-oxidation of Al-DOC and Fe-DOC in the lake, liberation of inorganic Al and Fe, precipitation of Al(OH)(3) and Fe(OH)(3), adsorption of P by the hydroxides, and sedimentation are responsible for the changes in water quality and long-term sediment characteristics. PMID:18440053

  9. Magnetic Signature of Glacial Flour in Sediments From Bear Lake, Utah/Idaho

    NASA Astrophysics Data System (ADS)

    Rosenbaum, J. G.; Dean, W. E.; Colman, S. M.; Reynolds, R. L.

    2002-12-01

    Variations in magnetic properties within an interval of Bear Lake sediments correlative with oxygen isotope stage 2 (OIS 2) and OIS 3 provide a record of glacial flour production for the Uinta Mountains. Like sediments of the same age from Upper Klamath Lake (OR), these Bear Lake sediments have high magnetic susceptibilities (MS) relative to non-glacial-age sediments and contain well-defined millennial-scale variations in magnetic properties. In contrast to glacial flour derived from volcanic rocks surrounding Upper Klamath Lake, glacial flour derived from the Uinta Mountains and deposited in Bear Lake by the Bear River has low magnetite content but high hematite content. The relatively low MS values of younger and older non-glacial-age sediments are due entirely to dilution by non-magnetic endogenic carbonate and to the effects of sulfidic alteration of detrital Fe-oxides. Analysis of samples from streams entering Bear Lake and from along the course of the Bear River demonstrates that, in comparison to other areas of the catchment, sediment derived from the Uinta Mountains is rich in hematite (high HIRM) and aluminum, and poor in magnetite (low MS) and titanium. Within the glacial-age lake sediments, there are strong positive correlations among HIRM, Al/Ti, and fine sediment grain size. MS varies inversely with theses three variables. These relations indicate that the observed millennial-scale variations in magnetic and chemical properties arise from varying proportions of two detrital components: (1) very fine-grained glacial flour derived from Proterozoic metasedimentary rocks in the Uinta Mountains and characterized by high HIRM and low MS, and (2) somewhat coarser material, characterized by higher MS and lower HIRM, derived from widespread sedimentary rocks along the course of the Bear River and around Bear Lake. Measurement of glacial flour incorporated in lake sediments can provide a continuous history of alpine glaciation, because the rate of accumulation

  10. Application of MODIS data in monitoring suspended sediment of Taihu Lake, China

    NASA Astrophysics Data System (ADS)

    Jiang, Xingwei; Tang, Junwu; Zhang, Minwei; Ma, Ronghua; Ding, Jing

    2009-09-01

    Application of MODIS in ocean color is mainly based on bands 8-16 with the spatial resolution of 1 000 m. This spatial resolution, however, can not meet the application demand of inland waters where the areas are relatively small. With the assumption of the black water at shortwave infrared (SWIR) wavelengths (>1 000 nm), we first propose an atmospheric correction method for bands 1 and 2 with their spatial resolution of 250 m, and we then establish a quantitative retrieval model for suspended sediment concentration retrieval using the in-situ data collected in Taihu Lake. We also use MODIS data to retrieve the suspended sediment concentration of Taihu Lake with the retrieval model. The comparison between the retrieved and measured suspended sediment concentrations confirms that our algorithm can provide reliable data for monitoring the suspended sediment in Taihu Lake.

  11. 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. PMID:27342902

  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. 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

  14. Magnetostratigraphy of Plio-Pleistocene Lake Sediments from Armenia

    NASA Astrophysics Data System (ADS)

    Kirscher, U.; Bachtadse, V.; Bruch, A.; Scharrer, S.; Abdul Aziz, H.

    2007-12-01

    The Pleistocene geology of Armenia is dominated by the widespread occurrence of lake sediments which testify rapid changes of the environmental conditions during the last 2 million years. These sediments are perfectly suited for paleoenvironmental studies and yield various fossil remains, which allow to reconstruct flora and fauna as well as climatic conditions during dispersal of early man like homo georgicus (1.8 Ma) into Eurasia. Unfortunately, however, precise dating of these sequences is still a matter of debate and absolute ages for basalts directly overlying the lacustrine diatomites range from 1.2 to 0.935 Ma. Addressing the age debate, a detailed magnetostratigraphic study has been carried out in the Vorotan river area near the town of Sisian. A total number of 250 oriented drill cores have been obtained from 5 sections covering 75 meters in stratigraphic thickness. First results demonstrate the high quality of the sampled material and, after removal of a present day overprint at demagnetization temperatures of around 150° C, a stable component of magnetization can be identified in the majority of the samples. Magnetizations of both normal and reverse polarities have been determined. In cases where the magnetic spectrum could not be resolved due to overlapping blocking spectra, great circle analysis was applied successfully to identify the characteristic direction of the NRM. The resulting mean direction for both polarity components plots slightly to the west of the direction of the present day magnetic field at the sampling site and has an inclination value of 55° . A positive reversal test suggests the primary character of these magnetizations. Plotting the characteristic directions in stratigraphic order reveals that the lowermost 50m of the composite profile are of inverse polarity, followed by 20m of normal and 5m of inverse polarity. Based on these preliminary results, and in combination with existing radiometric data, we interpret the zone of

  15. Heavy metal accumulation in lake sediments, fish (Oreochromis niloticus and Serranochromis thumbergi), and crayfish (Cherax quadricarinatus) in Lake Itezhi-tezhi and Lake Kariba, Zambia.

    PubMed

    Nakayama, Shouta M M; Ikenaka, Yoshinori; Muzandu, Kaampwe; Choongo, Kennedy; Oroszlany, Balazs; Teraoka, Hiroki; Mizuno, Naoharu; Ishizuka, Mayumi

    2010-08-01

    We measured the level of heavy metal accumulation in lake sediments, herbivorous (Oreochromis niloticus) and carnivorous (Serranochromis thumbergi) fish, and crayfish (Cherax quadricarinatus) from Lake Itezhi-tezhi (ITT) and Lake Kariba. We used atomic absorption spectrophotometry to quantify the levels of seven heavy metals (Cr, Co, Cu, Zn, Cd, Pb, and Ni). The sediment and the herbivorous fish O. niloticus accumulated a very high concentration of Cu in Lake ITT, most likely due to the discharge of Cu waste from a mining area 450 km upstream. The aquatic species we sampled in Lake Kariba had higher concentrations of Cr, Ni, and Pb relative to those in Lake ITT. This is most likely due to anthropogenic activities, such as the use of leaded petrol and antifouling agents in marine paints. Interestingly, we observed a negative correlation between the coefficient of condition (K) and Ni concentration in the crayfish hepatopancreas. Both O. niloticus and the crayfish had much higher biota-sediment accumulation factors (BSAF) for Cu, Zn, and Cd relative to Cr, Co, Pb, and Ni. The rank of BSAF values for O. niloticus (Cu>Cd>Zn) and C. quadricarinatus (Zn>Cd>Cu) differed from the expected ranks based on the general order of affinity of metals (Cd>Zn>Cu). PMID:20162262

  16. 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.

  17. Halomonas xiaochaidanensis sp. nov., isolated from a salt lake sediment.

    PubMed

    Liu, Wen; Zhang, Guojing; Xian, Wendong; Yang, Jian; Yang, Lingling; Xiao, Min; Jiang, Hongchen; Li, Wen-Jun

    2016-10-01

    A short-rod-shaped moderately halophilic bacterium, designated CUG 00002(T), was isolated from the sediment of Xiaochaidan salt lake in Qinghai Province, China by using R2A medium. The cells were Gram-staining negative, aerobic, forming creamy and circular colonies with diameters of 2-3 mm on R2A agar when incubated at 30 °C for 3 days. 16S rRNA gene-based phylogenetic analysis indicated that strain CUG 00002(T) belonged to the genus Halomonas in the class Gammaproteobacteria, showing highest sequence similarity of 97.1 and 96.7 % to Halomonas mongoliensis Z-7009(T) (=DSM 17332=VKM B2353) and Halomonas shengliensis SL014B-85(T) (=CGMCC 1.6444(T)=LMG 23897(T)), respectively. The predominant isoprenoid quinone was ubiquinone-9 (Q9), and the major fatty acids were C16:0, summed feature 3 (comprising C16:1 ω7c and/or C16:1 ω6c) and summed feature 8 (comprising C18:1 ω7c or C18:1 ω6c). The genomic DNA G+C content of strain CUG 00002(T) was 61.8 mol%. The above characteristics were consistent with the placement of the organism in the genus Halomonas. The level of DNA-DNA relatedness between CUG 00002(T) and its most closely related strain H. mongoliensis Z-7009(T) was 41.0 ± 1.6 %. Based on the results of phenotypic, phylogenetic and biochemical analyses, strain CUG 00002(T) represents a novel species of the genus Halomonas, for which the name Halomonas xiaochaidanensis sp. nov. is proposed. The type strain is CUG 00002(T) (=CCTCC AB 2014152(T)=KCTC 42685(T)). PMID:27177899

  18. Streptomyces aidingensis sp. nov., an actinomycete isolated from lake sediment.

    PubMed

    Xia, Zhan-Feng; Ruan, Ji-Sheng; Huang, Ying; Zhang, Li-Li

    2013-09-01

    A novel actinomycete strain, designated TRM 46012(T), was isolated from sediment of Aiding Lake in Tulufan Basin (42° 64' N 89° 26' E), north-west China. The strain was aerobic and Gram-staining-positive with an optimum NaCl concentration for growth of 0-5% (w/v). The isolate had sparse aerial mycelium and produced bud-shaped spores at the end of the aerial mycelium on ISP medium 4. The isolate contained ll-diaminopimelic acid as the diagnostic diamino acid and ribose as the major whole-cell sugar. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, phosphatidylinositol, phosphatidylinositol mannoside, one unidentified phospholipid and three unidentified glycolipids. The predominant menaquinones were MK-9(H₆), MK-9(H₈) and MK-9(H₄). The major fatty acids were iso-C(16:0), anteiso-C(17:0) and anteiso-C(15:0). The G+C content of the DNA was 74.4 mol%. Phylogenetic analysis showed that strain TRM 46012(T) had 16S rRNA gene sequence similarity of 95.7% with the most closely related species with a validly published name, Streptomyces cheonanensis, and it could be distinguished from all species in the genus Streptomyces by using the data from this polyphasic taxonomic study. On the basis of these data, strain TRM 46012(T) should be designated as a representative of a novel species of the genus Streptomyces, for which the name Streptomyces aidingensis sp. nov. is proposed. The type strain is TRM 46012(T) ( =CGMCC 4.5739(T) =NBRC 108211(T)). PMID:23456804

  19. Succession of lignocellulolytic bacterial consortia bred anaerobically from lake sediment.

    PubMed

    Korenblum, Elisa; Jiménez, Diego Javier; van Elsas, Jan Dirk

    2016-03-01

    Anaerobic bacteria degrade lignocellulose in various anoxic and organically rich environments, often in a syntrophic process. Anaerobic enrichments of bacterial communities on a recalcitrant lignocellulose source were studied combining polymerase chain reaction-denaturing gradient gel electrophoresis, amplicon sequencing of the 16S rRNA gene and culturing. Three consortia were constructed using the microbiota of lake sediment as the starting inoculum and untreated switchgrass (Panicum virgatum) (acid or heat) or treated (with either acid or heat) as the sole source of carbonaceous compounds. Additionally, nitrate was used in order to limit sulfate reduction and methanogenesis. Bacterial growth took place, as evidenced from 3 to 4 log unit increases in the 16S rRNA gene copy numbers as well as direct cell counts through three transfers on cleaned and reused substrate placed in fresh mineral medium. After 2 days, Aeromonas bestiarum-like organisms dominated the enrichments, irrespective of the substrate type. One month later, each substrate revealed major enrichments of organisms affiliated with different species of Clostridium. Moreover, only the heat-treated substrate selected Dysgonomonas capnocytophagoides-affiliated bacteria (Bacteroidetes). Towards the end of the experiment, members of the Proteobacteria (Aeromonas, Rhizobium and/or Serratia) became dominant in all three types of substrates. A total of 160 strains was isolated from the enrichments. Most of the strains tested (78%) were able to grow anaerobically on carboxymethyl cellulose and xylan. The final consortia yield attractive biological tools for the depolymerization of recalcitrant lignocellulosic materials and are proposed for the production of precursors of biofuels. PMID:26875750

  20. Anthropogenic marker evidence for accelerated sedimentation in Lake Illawarra, New South Wales, Australia

    NASA Astrophysics Data System (ADS)

    Chenhall, B. E.; Yassini, I.; Depers, A. M.; Caitcheon, G.; Jones, B. G.; Batley, G. E.; Ohmsen, G. S.

    1995-09-01

    The chronology of near-surface sediments in Lake Illawarra has been investigated using radiocarbon dating and anthropogenically derived substances including trace metals, ash, and137Cs. Sediments at depths about 1 m below the water-sediment interface ranged in age from Modern to 786 calendar years bp on the basis of radiocarbon dating of Notospisula trigonella valves. Multiple marker (for example ash-trace metals) depth-concentration sediment profiles yielded estimates of sedimentation rate ranging from 3 to 5 mm yr-1 at Griffins Bay to more than 16 mm yr-1 at Macquarie Rivulet. Sedimentation rates of approximately 10 mm yr-1 appeared to be typical of the western and southwestern portions of the lagoon. Rates of sediment accretion, prior to catchment clearing, urbanization, and industrialization have been estimated at less than 1 mm yr-1, thus indicating a general tenfold increase in sediment accumulation adjacent to the western foreshore caused by catchment development. Accelerated sedimentation in shallow coastal lagoons constitutes significant environmental impacts including shoaling, degradation of seagrass beds, and increased turbidity with consequent loss of aesthetic appeal. Management policy should be directed at attempts to reduce the amount of sediment input by the construction of strategically placed sediment retention ponds. Siltation within the shallow embayments of Lake Illawarra could be ameliorated by a carefully planned program of dredging.

  1. Assessing Li and other leachable geochemical proxies for paleo-salinity in lake sediments from the Mono Basin, CA (USA)

    NASA Astrophysics Data System (ADS)

    Sahajpal, Rahul; Zimmerman, Susan R. H.; Datta, Saugata; Hemming, N. Gary; Hemming, Sidney R.

    2011-12-01

    Regional climate-driven hydrological changes are accompanied by salinity changes in closed basin lakes. We have investigated acid leachable Li, along with other leachable ions including Mg, Ca and Sr, as geochemical proxies of salinity in lake sediments in the Mono Basin, California. All the elements in the acid leachable suite show a strong correlation with paleo-lake level estimates based on physical and stratigraphic evidence. The CaCO 3 content of lake sediments, which has been shown to be a reliable proxy for lake level changes in the Mono basin and the adjoining Owens Lake basin, corresponds well with our acid-leachable proxy data.

  2. Lake restoration by hypolimnetic Ca(OH)2 treatment: impact on phosphorus sedimentation and release from sediment.

    PubMed

    Dittrich, Maria; Gabriel, Oliver; Rutzen, Christian; Koschel, Rainer

    2011-03-15

    A whole-lake hypolimnetic Ca(OH)(2) addition, that induced calcium carbonate precipitation, combined with deep water aeration has been applied to eutrophic Lake Luzin, Germany during 1996-1998. In this study we investigated the dynamic of phosphorus and its binding forms in seston and sediment before and during the treatment. The sedimentation rates of phosphorus increased within three years of induced calcite precipitation. The phosphorus binding forms shifted to the calcite-bound phosphorus in the settling matter. The increase of calcite-bound P in the settling material did not coincide with the maximum induced CaCO(3)-precipitation caused by the hypolimnetic addition of Ca(OH)(2). An impact of chemicals additions and pH on phosphorus binding forms in seston and surface sediments has been studied in laboratory experiments with sediment core incubations and slurry experiments. Laboratory studies showed that the lowest phosphorus flux from sediment was related to the experiment with pH=7 in overlaying water adjusted with Ca(OH)(2). The adjusting of pH with Ca(OH)(2) leads to a lower P flux of 2.3 mg Pm(-2)d(-1), while the highest P-flux is attributed to the experiment with the pH which was adjusted with NaOH. Phosphorus fraction which reflects phosphorus binding on carbonates in surface sediments increased within one year of treatment, enhancing the phosphorus retention capacity of sediments. PMID:21292312

  3. 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.

  4. [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

  5. Molecular genetic analyses of historical lake sediments from the East African Rift Valley

    NASA Astrophysics Data System (ADS)

    Epp, L. S.; Stoof, K.; Trauth, M. H.; Tiedemann, R.

    2009-04-01

    Ancient DNA research, especially that of environmental samples, has to date focussed mainly on samples obtained from colder regions, owing to better DNA preservation. We explored the potential of using ancient DNA from sediments and sediment cores of shallow lakes in Kenya. These lakes, located in the eastern branch of the East African Rift Valley, are in close proximity, yet display strikingly different hydrological and geological features. Present day lakes range in alkalinity from pH 11 (Lake Elmenteita) to pH 8 (Lake Naivasha), and in depth from less than one meter to 15 meters. Historically they have undergone a number of drastic changes in lake level and environmental conditions, both on geological timescales and during the last centuries. Within this setting we employed molecular genetic methods to study DNA from recent and historic lake sediments, focussing on rotifers and diatoms. We analyzed population and species succession in the alkaline-saline crater lake Sonachi since the beginning of the 19th century, as well as distributions in recent and historic sediments of other lakes of the East African Rift System. To specifically detect diatoms, we developed a protocol using taxon-specific polymerase chain reactions and separation of products by denaturing high performance liquid chromatography (DHPLC). Employing this protocol we retrieved "ancient" DNA from a number of taxonomically diverse organisms, but found diatoms only in sediments younger than approximately 90 years. Using higly specific reactions for rotifers of the genus Brachionus, we tracked species and population succession in Lake Sonachi during the last 200 years. Populations were dominated by a single mitochondrial haplotype for a period of 150 years, and two putatively intraspecific turnovers in dominance occurred. They were both correlated to major environmental changes documented by profound visible changes in sediment composition of the core: the deposition of a volcanic ash and a

  6. 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

  7. 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.

  8. High-resolution microfacies analysis and tephrochronology of varved sediments from Lake Tiefer See (NE Germany)

    NASA Astrophysics Data System (ADS)

    Dräger, Nadine; Wulf, Sabine; Kienel, Ulrike; Dulski, Peter; Ott, Florian; Slowinski, Michál; Theuerkauf, Martin; Brauer, Achim

    2014-05-01

    Annually laminated (varved) lake sediments represent unique archives in continental areas providing both, precise chronologies and up to seasonally resolving proxy data. Lake Tiefer See in NE Germany provides such an archive that permits an integrated multi-proxy study based on high-resolution sediment analyses and monitoring of lake condition and deposition of subannual laminae. Lake Tiefer See is located within the terminal moraine of the Pommeranian ice advance of the last glaciation and is part of the Klocksin Lake Chain which acted as a glacial gully system. Coring campaigns at the deepest part of the lake (~60 m depth) yielded 7 sediment profiles, 3 of which reached glacial sand deposits at the base. From these individual profiles a ~11 m long continuous composite profile has been established. The chronology of the core sequence is based on varve counting, AMS 14C dating of terrestrial plant remains and identification of cryptotephras. Tephra layers of Eifel- and Icelandic provenance in the lowermost part of the core sequence suggest an onset of lake sedimentation in the late Allerød at about 13 000 years BP and an onset of varve preservation at the beginning of the Holocene. A combined approach of microfacies analyses on thin sections and µ-XRF analyses on split sediment cores has been carried out. In the first place we identified well and poorly varved or even homogeneous intervals. Poorly and non-varved intervals are characterised by higher Ti and K count rates suggesting increased detrital matter flux into the lake by surface runoff and/-or aeolian transport. The occurrence of poorly varved intervals increases towards the top probably triggered by either climate and environmental changes or anthropogenic influences leading to intensified lake mixing. The overarching goal within the ICLEA objective is to compare the sediment record from Lake Tiefer See with another varved record from Lake Czechowskie, located ca 400 km to the East in central northern

  9. Inferring sources for mercury to inland lakes using sediment chronologies of polycyclic aromatic hydrocarbons.

    PubMed

    Parsons, Matthew J; Long, David T; Giesy, John P; Kannan, Kurunthachalam

    2014-09-20

    Sediment chronologies from inland lakes suggest the influence of local to sub-regional scale sources for mercury (Hg). However, apportionment of sources for Hg using sediment chronologies is difficult due to the mixing of sources and pathways. Mercury and polycyclic aromatic hydrocarbons (PAH) often share common sources and pathways into the environment. Thus, chronologies of PAHs in dated cores of sediments might be a useful tool to infer sources of Hg. Sediment cores from seven inland lakes of Michigan were collected for measurement of PAHs and Hg and dated by use of (210)Pb. PAH concentrations and ratios of kinetic and thermodynamic PAH compounds were used to infer sources of Hg. Ratios indicate the existence of modern combustion sources to each lake and historic combustion sources to lakes near cement kilns and an iron foundry. Coal combustion sources were identified for two lakes near urban centers. Whereas a petroleum combustion source was identified for a lake that has a coal fired power plant along its shoreline. These results have implications for the cycling of Hg on local to regional scales. PMID:24875801

  10. Sediment toxicity and deformities of chironomid larvae in Lake Piediluco (Central Italy).

    PubMed

    Di Veroli, Alessandra; Selvaggi, Roberta; Pellegrino, Roberto Maria; Goretti, Enzo

    2010-03-01

    The chemical analysis of the bottom sediments of the Lake Piediluco (Central Italy) has been carried out in order to individuate the potential correlation between the sediment toxicity and the high incidence of mouthpart deformities in chironomid larvae (biological indicators) found in this lake. The environmental contamination has been analyzed by determining the concentrations of the main heavy metals (lead, copper, cadmium, chromium, zinc and nickel), and the concentrations of organic compounds of anthropic source: PAHs, NPPs and OCPs. Heavy metals concentrations have pointed out a non-elevated contamination grade for the Lake Piediluco. The highest level of metals has been detected in the western area that feels the effect of the continuous tributaries incoming load. Also, concerning PAHs, NPPs and OCPs the lake does not present high values of pollution. The highest concentrations of the organic toxicants has been observed in the eastern sector of the lake, which presents typical lentic characteristics. A clear relationship has not found between the toxic substances present in the lacustrine sediments and the deformities incidence for chironomid larvae, which represent an index of environmental alteration. Probably, the mouthpart deformities found in the chironomid larvae of Chironomus plumosus are affected by a synergic action due to the whole toxic mixture present in the sediments of the Lake Piediluco. PMID:20172586

  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. Vertical structure of organic-rich fine sediment relevant to resuspension: Lake Apopka, Florida

    NASA Astrophysics Data System (ADS)

    Mehta, Ashish; Manning, Andrew

    2014-05-01

    Wind-induced resuspension potential of organic-rich bottom sediment in many shallow lakes of Florida is a major management concern. If resuspension remains unabated, high oxygen demand of these waters typically rich in nutrients tends to bring about an abundance of toxic algae and drastic loss of fish population. A case in point is the highly eutrophic Lake Apopka in central Florida which has an area of 12,500 ha and a mean depth of about 2 m. The development of a water management strategy for this and similar lakes requires a thorough understanding of fine sediment dynamics peculiar to bottom muck. Although lake muck is fine-grained, from its surface down to a depth of 1 to 2 m it is significantly stratified with respect to material composition and density. As a result, characteristic parameters defining the state of the bottom, its resuspension by wind and settling of suspended matter tend to differ from those of beds of inorganic matter. In addition, above the bed surface defined by the so-called space-filling density of solids, a fluid-like, almost entirely organic, "fluff" layer can exist without dewatering to form a solid bed. Modeling the response of this lake sediment to wind requires a detailed characterization of the state and transport behavior of stratified muck. This characterization and its significance in sediment transport modeling are described for Lake Apopka.

  14. 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.

  15. Spatio-temporal Variation of Sediment Methanotrophic Microorganisms in a Large Eutrophic Lake.

    PubMed

    Yang, Yuyin; Zhao, Qun; Cui, Yahui; Wang, Yilin; Xie, Shuguang; Liu, Yong

    2016-01-01

    Aerobic methane-oxidizing bacteria (MOB) play a crucial role in mitigating the methane emission from lake ecosystems to the atmosphere. However, the distribution of methanotrophic community in shallow and eutrophic lake and its influential factors remain essentially unclear. The present study investigated sediment methanotrophic microorganisms at different sites in eutrophic freshwater Dianchi Lake (China) in two different seasons. The abundance, diversity, and structure of sediment methanotrophic community showed a profound spatial and seasonal variation. The pmoA gene copy number in lake sediments ranged from 8.71 ± 0.49 × 10(4) to 2.09 ± 0.03 × 10(7) copies per gram of dry sediment. Sediment methanotrophic communities were composed of Methylococcus and Methylobacter (type I methanotrophs) and Methylosinus (type II methanotrophs), while type I MOB usually outnumbered type II MOB. Moreover, ammonia nitrogen was found to be a potential determinant of methanotrophic community structure in Dianchi Lake. PMID:26318324

  16. 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. PMID:26662787

  17. 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.

  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. PMID:26923240

  19. Immunoassay screening of sediment cores for polychlorinated biphenyls, Devil's Swamp Lake near Baton Rouge, Louisiana, 2004

    USGS Publications Warehouse

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

    2004-01-01

    Devil?s Swamp Lake near Baton Rouge, Louisiana, constructed by dredging in 1973 in Devil?s Swamp along the Mississippi River, is contaminated with polychlorinated biphenyls (PCBs). This study investigated the possible historical contribution of PCBs from a hazardous-chemical disposal facility by way of a wastewater drainage ditch that operated from 1971 to 1993. Six sediment cores from the lake and three bottom-material samples from the drainage ditch were collected on October 5, 2004, and analyzed for PCBs using an immunoassay screening method. The results were used to evaluate qualitatively the historical input record of PCBs to the lake. Deposition dates in three of the cores were estimated by assuming that penetration of the push corer was stopped by firmer, pre-lake materials that mark the 1973 subsurface level of dredging. Sixty-one samples from five of the six cores and three bottom-material samples from the drainage ditch were analyzed. PCBs were at higher concentrations in ditch bottom material (about 1.1 to 2.2 milligrams per kilogram) than in cores from sites near where the ditch enters the lake (about 0.1 to 1.0 milligrams per kilogram). The highest concentrations of PCBs (maximum about 15 milligrams per kilogram) were detected in lake-bottom sediment about 350 meters west of where the drainage ditch enters the lake. Detection rates and median PCB concentrations were higher in all of the dated core sediments deposited before about 1990 than after 1990.

  20. Annually laminated lake sediments as recorders of flood events: evidence from combining monitoring and calibration

    NASA Astrophysics Data System (ADS)

    Kämpf, Lucas; Brauer, Achim; Mueller, Philip; Güntner, Andreas; Merz, Bruno

    2015-04-01

    The relation of changing climate and the occurrence of strong flood events has been controversially debated over the last years. One major limitation in this respect is the temporal extension of instrumental flood time series, rarely exceeding 50-100 years, which is too short to reflect the full range of natural climate variability in a region. Therefore, geoarchives are increasingly explored as natural flood recorders far beyond the range of instrumental flood time series. Annually laminated (varved) lake sediments provide particularly valuable archives since (i) lakes form ideal traps in the landscape continuously recording sediment flux from the catchment and (ii) individual flood events are recorded as detrital layers and can be dated with seasonal precision by varve counting. Despite the great potential of varved lake sediments for reconstructing long flood time series, there are still some confinements with respect to their interpretation due to a lack in understanding processes controlling the formation of detrital layers. For this purpose, we investigated the formation of detrital flood layers in Lake Mondsee (Upper Austria) in great detail by monitoring flood-related sediment flux and comparing detrital layers in sub-recent sediments with river runoff data. Sediment flux at the lake bottom was trapped over a three-year period (2011-2013) at two locations in Lake Mondsee, one located 0.9 km off the main inflow (proximal) and one in a more distal position at a distance of 2.8 km. The monitoring data include 26 floods of different amplitude (max. hourly discharge=10-110 cbm/s) which triggered variable fluxes of catchment sediment to the lake floor (4-760 g/(sqm*d)). The comparison of runoff and sediment data revealed empiric runoff thresholds for triggering significant detrital sediment influx to the proximal (20 cbm/s) and distal lake basin (30 cbm/s) and an exponential relation between runoff amplitude and the amount of deposited sediment. A succession of

  1. 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. PMID:25612141

  2. 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.

  3. 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. PMID:22464858

  4. Uncoupled organic matter burial and quality in boreal lake sediments over the Holocene

    NASA Astrophysics Data System (ADS)

    Chmiel, Hannah E.; Niggemann, Jutta; Kokic, Jovana; Ferland, Marie-Ève; Dittmar, Thorsten; Sobek, Sebastian

    2015-09-01

    Boreal lake sediments are important sites of organic carbon (OC) storage, which have accumulated substantial amounts of OC over the Holocene epoch; the temporal evolution and the strength of this Holocene carbon (C) sink is, however, not well constrained. In this study we investigated the temporal record of carbon mass accumulation rates (CMARs) and assessed qualitative changes of terrestrially derived OC in the sediment profiles of seven Swedish boreal lakes, in order to evaluate the variability of boreal lake sediments as a C sink over time. CMARs were resolved on a short-term (centennial) and long-term (i.e., over millennia of the Holocene) timescale, using radioactive lead (210Pb) and carbon (14C) isotope dating. Sources and degradation state of terrestrially derived OC were identified and characterized by molecular analyses of lignin phenols. We found that CMARs varied substantially on both short-term and long-term scales and that the variability was mostly attributed to sedimentation rates and uncoupled from the OC content in the sediment profiles. The lignin phenol analyses revealed that woody material from gymnosperms was a dominant and constant OC source to the sediments over the Holocene. Furthermore, lignin-based degradation indices, such as acid-to-aldehyde ratios, indicated that postdepositional degradation in the sediments was very limited on longer timescales, implying that terrestrial OC is stabilized in the sediments on a permanent basis.

  5. 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

  6. Current status and historical variations of phthalate ester (PAE) contamination in the sediments from a large Chinese lake (Lake Chaohu).

    PubMed

    Kang, Lei; Wang, Qing-Mei; He, Qi-Shuang; He, Wei; Liu, Wen-Xiu; Kong, Xiang-Zhen; Yang, Bin; Yang, Chen; Jiang, Yu-Jiao; Xu, Fu-Liu

    2016-06-01

    The residual levels of phthalate esters (PAEs) in the surface and two core sediments from Lake Chaohu were measured with a gas chromatograph-mass spectrometer (GC-MS). The temporal-spatial distributions, compositions of PAEs, and their effecting factors were investigated. The results indicated that di-n-butyl phthalate (DnBP), diisobutyl phthalate (DIBP), and di(2-ethylhexyl) phthalate (DEHP) were three dominant PAE components in both the surface and core sediments. The residual level of total detected PAEs (∑PAEs) in the surface sediments (2.146 ± 2.255 μg/g dw) was lower than that in the western core sediments (10.615 ± 9.733 μg/g) and in the eastern core sediments (5.109 ± 4.741 μg/g). The average content of ∑PAEs in the surface sediments from the inflow rivers (4.128 ± 1.738 μg/g dw) was an order of magnitude higher than those from the lake (0.323 ± 0.093 μg/g dw), and there were similar PAE compositions between the lake and inflow rivers. This finding means that there were important effects of PAE input from the inflow rivers on the compositions and distributions of PAEs in the surface sediments. An increasing trend was found for the residual levels of ΣPAEs, DnBP, and DIBP from the bottom to the surface in both the western and eastern core sediments. Increasing PAE usage with the population growth, urbanization, and industrial and agricultural development in Lake Chaohu watershed would result in the increasing production of PAEs and their resulting presence in the sediments. The significant positive relationships were also found between the PAE contents and the percentage of sand particles, as well as TOC contents in the sediment cores. PMID:26330308

  7. Historical profiles of PCB in dated sediment cores suggest recent lake contamination through the "halo effect".

    PubMed

    Naffrechoux, Emmanuel; Cottin, Nathalie; Pignol, Cécile; Arnaud, Fabien; Jenny, Jean-Philippe; Perga, Marie-Elodie

    2015-02-01

    We investigated the major sources of polychlorinated biphenyls (PCB) and interpreted the environmental fate processes of these persistent organic pollutants in the past and current PCB contamination of three large, urbanized, French peri-alpine lakes. Dated sediment cores were analyzed in order to reconstruct and compare the historical contamination in all three lakes. Stratigraphic changes of PCB contents and fluxes were considered as revealing the temporal dynamics of PCB deposition to the lakes and the distribution of the seven indicator congeners (further referred to as PCBi) as an indicator of the main contamination origin and pathway. Although located within a single PCB industrial production region, concentration profiles for the three lakes differed in timing, peak concentration magnitudes, and in the PCBi congeners compositions. PCBi fluxes to the sediment and the magnitude of the temporal changes were generally much lower in Lake Annecy (0.05-2 ng·cm(-2)·yr(-1)) as compared to Lakes Geneva (0.05-5 ng·cm(-2)·yr(-1)) and Bourget (5-290 ng·cm(-2)·yr(-1)). For all three lakes, the paramount contamination occurred in the early 1970s. In Lakes Annecy and Bourget, PCB fluxes have declined and plateaued at 0.5 and 8 ng·cm(-2)·yr(-1), respectively, since the early 1990s. In Lake Geneva, PCB fluxes have further decreased by the end of the XX(th) century and are now very low. For the most contaminated lake (Lake Bourget), the high PCBi flux (5-290 ng·cm(-2)·yr(-1)) and the predominance of heavy congeners for most of the time period are consistent with a huge local input to the lake. This still high rate of Lake Bourget is explained by transport of suspended solids from one of its affluents, polluted by an industrial point source. Intermediate historical levels and PCBi distribution over time for Lake Geneva suggest a mixed contamination (urban point sources and distant atmospheric transport), while atmospheric deposition to Lake Annecy explains its lowest

  8. 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

  9. 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.

  10. [Composition and Environmental Effects of LFOM and HFOM in "Incense-Ash" Sediments of West Lake, Hangzhou, China].

    PubMed

    Li, Jing; Zhu, Guang-wei; Zhu, Meng-yuan; Gong, Zhi-jun; Xu, Hai; Yang, Gui-jun

    2015-06-01

    To understand the organic matter pollution characteristic and its relationship with nitrogen, phosphorus and other nutrients in sediments of high organic matter type of urban shallow lakes, the organic matter content, light fraction organic matter (LFOM), heavy fraction organic matter (HFOM), and nitrogen and phosphorus contents were investigated in eight different regions of West Lake, Hangzhou. The results showed that, the organic matter content of the west lake sediment was 28-251 g x kg(-1), belonging to typical high organic matter sediment. The difference of organic matter content in different lake sediments was very big. The sediments located at the input site of water diversion engineering had significantly lower organic content than the rest regions. The LFOM content of West Lake sediment ranged 0.57-9.17 g x kg(-1), which averagely occupied 2.83% of the total organic matter, and the HFOM content ranged 5.35-347.41 g x kg(-1), which occupied more than 90% of the total organic matter. Compared to other shallow lakes located in China, sediments of West Lake had significantly high percentage of HFOM/LFOM ratio. But the HFOM content was obviously on the high side, reflecting the west lake as an urban lake with a long history, as well as high organic matter pollution load and sediment humification degree. Both the content and the ratio of LFOM/HFOM in sediment were related to nitrogen and phosphorus contents in sediment. This suggested that the composition of organic matter in West Lake sediments had potential control ability for the internal loading of N and P of the lake. PMID:26387305

  11. 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. PMID:27102272

  12. 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.

  13. [Characteristics of nitrogen pollution and the potential mineralization in surface sediments of Dianchi Lake].

    PubMed

    Meng, Ya-Yuan; Wang, Sheng-Rui; Jiao, Li-Xin; Liu, Wen-Bin; Xiao, Yan-Bo; Zu, Wei-Mei; Xu, Tian-Min; Ding, Shuai; Zhou, Tong

    2015-02-01

    The nitrogen content, its different forms and their spatial distribution were studied by using the 53 sediment samples from different sites in Dianchi Lake. Thereafter, the potential nitrogen mineralization ability of the sediments and their pollution characteristics were also explored to understand the influencing factors of nitrogen pollution and its release risk from the sediment surface to the overlying water of Dianchi. The results showed: (1) the average total nitrogen content of surface sediment in Dianchi Lake was 3 515. 60 mg x kg(-1), which was at a high level from the inlets in Caohai Northeast thinning digging area, Panlong River and the Haikou into Dianchi Lake, but relatively low in Baoxiang River Estuary dredging area. The total organic nitrogen (TON) content, accounting for 85.86% of TN, was at a high level; on the other hand, the dissolved inorganic nitrogen ( DIN) content was lower, which accounted for 14.10% of TN. The spatial distribution of TON and TN kept the same trend, but not the DIN. Compared with other Lakes of China, the nitrogen content of sediment in Dianci was at a high level, and the extent of pollution was just below the serious polluted City Lakes. (2) The average potential mineralizable nitrogen (PMN) content of Lake Dianchi was 1 154.76 mg x kg(-1), accounting for 32.90% of TN, which raised the potential risk of its release into the overlying water. Higher PMN was found in the Caohai Lake area and the inlet of Panlong River in the North, the inlet of Luolong Rive in the Middle Lake, the inlet of Baiyukou Lake and Liangwang River in the South. Nowadays, the pH value of Dianchi Lake was favorable for its sediment nitrogen mineralization, and its nitrogen mineralization was affected by the release of NH4(+) -N from organic matter. In the heavy polluted area, the concentration of the overlying water nitrogen was seriously affected by nitrogen mineralization of sediment from Dianchi, while the light polluted area was less affected

  14. A New 62-sample Record of the Mono Lake Excursion Waveform from the Depocenter Sediments of Summer Lake, OR

    NASA Astrophysics Data System (ADS)

    Negrini, R. M.; McCuan, D. T.; Horton, R. A.; Verosub, K. L.

    2011-12-01

    A new core from Summer Lake, Oregon provides the primary datset for a composite, 62-sample record of the Mono Lake Excursion (MLE) waveform. The magnetograms and virtual geomagnetic poles (VGPs) are consistent with those associated with the MLE record from Mono Lake (e.g., Liddicoat and Coe, 1979). The added detail from this new record firmly establishes three distinct VGP clusters centered first on easternmost Asia/Siberia, then on Europe, and, finally, on North America. The jumps between clusters involve typically one sample, which represents only a few decades of time. The excursion is bracketed by tephra of known age (the Mount St. Helens Cy 46.0 ± 6 ka and the Wono 27.3 ± 0.3 14C kyr B.P.) and the age of the excursion is ~28 14C kyr B.P based on an average of five radiocarbon ages from below, within and above the excursion interval. A second waveform that exhibits shallowing inclinations and easterly declination swings upsection is truncated by a prominent unconformity. These PSV features and the associated RPI leading up to this unconformity correlate with those of the onset of the Laschamp Excursion (Lund et al., 2005). Both radiocarbon and PSV correlations support missing sediment from the Summer Lake record between 42.5 and 38 GISP2 ka. This sediment hiatus correlates to unconformities or lowstands in other Great Basin lakes suggesting a Heinrich 4-induced drought that affected much of western North America.

  15. Occurrence, distribution, and ecological risk assessment of potentially toxic elements in surface sediments of Lake Awassa and Lake Ziway, Ethiopia.

    PubMed

    Mekonnen, Kebede N; Ambushe, Abayneh A; Chandravanshi, Bhagwan S; Redi-Abshiro, Mesfin; McCrindle, Robert I

    2015-01-01

    Microwave-assisted acid digestion and modified aqua regia (HNO3:HCl:HF:H3BO3) leaching techniques were used for the determination of 15 potentially toxic elements (V, Cr, Fe, Mn, Co, Ni, Cu, Zn, As, Se, Ag, Cd, Sn, Hg and Pb) in sediment samples from Lake Awassa and Lake Ziway, Ethiopia. The digests were subsequently analyzed by inductively coupled plasma-mass spectrometry (ICP-MS) and inductively coupled plasma-optical emission spectrometry (ICP-OES). Mercury was directly determined in the solid samples using an elemental mercury analyzer. The precision and accuracy of the digestion procedures were verified using certified reference materials. The experimental results were in good agreement with the certified values (P < 0.05) and the recoveries were quantitative (>90%). The average relative standard deviations were below 10%. There is significant correlation between the two lakes at the 0.01 level (2-tailed). Using the sediment quality guidelines, both lakes are heavily polluted with Zn and some of the sites are heavily polluted with Cu, Ni and Pb. Based on effect range low (ERL) - effect range medium (ERM), in both lakes for Ag were greater than the ERM, indicating that the areas could be toxic to aquatic organisms, while for Cr, Cu, As and Hg the values were less than ERL. PMID:25438135

  16. Results of a detailed infill lake-sediment survey in the Snow Lake area: Evaluation and comparison of grab sample and short core data

    USGS Publications Warehouse

    Friske, P.W.B.

    1996-01-01

    As part of the Exploration Science and Technology Initiative (EXTECH) program a detailed infill lake-sediment and water survey was undertaken in the Snow Lake area during the fall of 1991. This involved the collection of 346 lake sediment grab samples and concomitant waters. In 1993, additional work was undertaken involving the collection of 23 short cores from selected grab sample sites. The primary objectives of the infill survey and short core work were to: 1) evaluate the effectiveness of lake sediment geochemistry in detecting known mineralization in the Snow Lake area; 2) evaluate and develop new approaches in the use of lake sediment geochemistry; and, 3) define, if possible, new exploration targets. At most sites, data from the cores verify the original grab sample results. However, at a few sites the original anomalous grab sample results are interpreted as being related to contamination as opposed to naturally elevated levels. An unusually thick sequence of contaminated surface sediments with extremely high concentrations of trace metals is a likely contributing factor, a condition which is restricted to lakes in the immediate vicinity of local anthropogenic activity. Collection of lake cores provides a useful new approach to the follow-up of grab sample data and to the application of lake sediment geochemistry, particularly in areas with significant local contamination. Much of the known mineralization in the area is clearly reflected by the lake sediment data. Character of the anomalies mirror the composition of the nearby mineralization. The lake sediment data also identify a number of areas that warrant further investigation, several of which are discussed.

  17. 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.

  18. 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

  19. Sediment-water gas exchange in two Swedish lakes measured by Eddy Correlation

    NASA Astrophysics Data System (ADS)

    Kokic, J.; Sahlee, E.; Brand, A.; Sobek, S.

    2014-12-01

    Lake sediments are hotspots for carbon (C) cycling, acting both as sinks and sources through C burial and production of carbon dioxide (CO2) and methane. The fate of this CO2 in the water column is controlled by bottom water turbulence, a factor not accounted for in current estimates of sediment CO2 fluxes. This study is aimed to quantify the turbulent CO2 flux across the sediment-water interface (SWI) by measuring the oxygen (O2) flux with the non-invasive Eddy Correlation (EC) method that combines measurements of 3D velocity (ADV) and O2 fluctuations with a microsensor. Using the metabolic relation (respiratory quotient, RQ) of O2 and CO2 derived from a sediment incubation experiment we present the first estimates of turbulent lake sediment CO2 flux from two boreal lakes in Sweden (Erssjön and Erken, 0.07 km2 and 23.7 km2 respectively). Only ~10 % of the total dataset was extracted for flux calculations due to poor signal-to-noise ratio in the velocity and O2 signals. The sediment in Lake Erssjön was both consuming and producing O2, related to bacterial respiration and photosynthesis. Mean O2 flux was -0.19 and 0.17 μmol O2 m-2 sec-1, comparing to 0.04 μmol O2 m-2 sec-1 derived from the sediment incubation experiment. Fluxes for Lake Erken are still to be determined. Experimentally derived RQ of the both lake sediments were close to unity implying that in-situ CO2 fluxes are of similar magnitude as O2 fluxes, varying between -0.15 and 0.18 μmol C m-2 sec-1. The first measurement of turbulent sediment O2 flux and estimate of turbulent CO2 flux from a small boreal lake show higher and more variable fluxes than previously found in experimental studies. The low amount of data extracted for flux calculations (~10%) point towards the difficulties in EC measurement in low-turbulence environments. On-going work focuses on the turbulence structure in lakes and its influence on the gas fluxes at the SWI.

  20. 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.

  1. 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

  2. Heavy metal release from metal-sulfide contaminated lake sediments exposed to artificial aeration

    SciTech Connect

    Schaumloffel, J.C.; Filby, R.H.; Moore, B.C.

    1995-12-01

    Hypolimnetic aeration (a form of artificial aeration) has gained popularity in recent years as a lake restoration and management tool. The addition of oxygen to eutrophic lakes by hypolimnetic aeration has been shown to increase overall water quality, without disturbing thermal stratification. The effects of increasing dissolved oxygen levels by aeration on the chemistry of heavy metals in lakes where the sediments are contaminated and the possible repercussions, however, have yet to be investigated. In this laboratory study, sediments collected from a lake contaminated with metal-sulfides were exposed to various levels of dissolved oxygen in the overyling water column. concentrations of zinc, cadmium, and lead in the water column were shown to increase concomitantly with increasing concentrations of sulfate in the water as aeration progressed. The effects of varying concentrations of dissolved oxygen, as well as other factors effecting the availability of previously insoluble heavy metals will be discussed.

  3. Assimilation of satellite images into a sediment transport model of Lake Michigan.

    SciTech Connect

    Stroud, J.; Lesht, B.; Beletsky, D.; Stein, M.; Univ. of Pennsylvania; NOAA; Univ. of Michigan; Univ. of Chicago

    2009-01-01

    In this paper we develop and examine several schemes for combining daily images obtained from the Sea-viewing Wide Field Spectrometer (SeaWiFS) with a two-dimensional sediment transport model of Lake Michigan. We consider two data assimilation methods, direct insertion and a kriging-based approach, and perform a forecasting study focused on a 2-month period in spring 1998 when a large storm caused substantial amounts of sediment resuspension and horizontal sediment transport in the lake. By beginning with the simplest possible forecast method and sequentially adding complexity we are able to assess the improvements offered by combining the satellite data with the numerical model. In our application, we find that data assimilation schemes that include both the data and the lake dynamics improve forecast root mean square error by 40% over purely model-based approaches and by 20% over purely data-based approaches.

  4. A 2000-year record of solar forcing on varved lake sediment in eastern Finland

    NASA Astrophysics Data System (ADS)

    Haltia-Hovi, Eeva; Saarinen, Timo; Kukkonen, Maaret

    2007-03-01

    A high-resolution study was performed on varved sediments from Lake Lehmilampi in eastern Finland. Varve data was collected by digital image analysis using standard 1.8 mm thick samples impregnated in epoxy and X-rayed. Climatic variability is imprinted on varve properties (varve thickness and accumulation of mineral and organic matter) during the last 2000 years. The cumulative counting error of the varve record is estimated as 2.3%. Qualitative comparison of varve parameters and residual Δ 14C constructed from tree-rings revealed close correspondence between the two records, suggesting solar forcing on lake sedimentation. Classical climatic periods of the last millennia, Medieval Climate Anomaly (1060-1280 in the varve record) and Little Ice Age (cooler phases culminating in 1340, 1465, 1545, 1680, 1850 and also in 1930 in the varve record) are clearly evident in the varve record. At present the physical link between solar activity levels and lake sedimentation has not been established.

  5. [Character and sources identification of heavy metals contamination in sediment from the core sediment in Nanshan Lake, the Zhalong wetland].

    PubMed

    Su, Dan; Zang, Shu-Ying; Ye, Hua-Xiang; Sun, Li; Jia, Xiao-Dan; Li, Miao

    2012-06-01

    NSH2 sediment core from Nanshan Lake in the south of Zhalong wetland was studied, which was a typical lake for both empolder and aquaculture. The vertical distributions of heavy metals (Hg, Cd, Pb, Cr, As, Mn, Ag, Cu, Co, Fe and Zn) were investigated. The method of principal component analysis (PCA) was adopted to apportion the sources of heavy metals, and particle size, combined with 210Pb(ex) dating data were used to indicate characteristics, sources and polluted history of heavy metals in lake sediments since 1829. The results showed that: 1) the trend of changes in accumulation in the sedimentation was rather slow in the earlier stage, then was fast in the middle stage, and finally slowed down again in the later stage. The history of elements pollution is correspondent with the production of human activities and policies of soil and water conservation of Nanshan Lake; 2) the contents of all elements varied smoothly before 1957, and which fluctuated slightly from 1957 to 1985. The contents of Hg, Cd and Ag increased obviously since 1985. The sources of heavy metals determined were mainly from sewage, the loss of fertilizers, and combustion of fuel such as coal and gasoline; 3) natural sources of the degradation of organic matter, rock weathering and erosion, as well as the source of industrial emissions, with the contributions of 50.14%, 19.90% and 10.32%, respectively. High potential risk of heavy metals existed in NSH2 sediment core. Hence, enough attention must be paid to the pollution control of lakes. Therefore, this study can provide basic data for help wetland ecological environment improvement in Zhalong wetland. PMID:22946160

  6. 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. PMID:21950768

  7. 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.

  8. 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.

  9. Characterization and evaluation of phosphate microsensors to monitor internal phosphorus loading in Lake Erie sediments.

    PubMed

    Ding, Xue; Behbahani, Mohsen; Gruden, Cyndee; Seo, Youngwoo

    2015-09-01

    Monitoring phosphate concentration is very important to prevent and control eutrophication in natural waters. In this study, cobalt-based microsensors were modified, characterized, and tested to monitor internal soluble phosphorous (SRP) loading in lakes with improved detection limits. The effectiveness of surface modification on the performance of a cobalt-based microelectrode was fully examined by determining detection limit, response time, selectivity, interference with ions (sulfate, nitrate, and nitrite) and dissolved oxygen (DO). To assess their performance, phosphate sensors were applied to sediment samples collected from Lake Erie. SRP loading from sediments was determined under different DO conditions. After increasing the phosphate sensing area and modifying the surface, phosphate microsensors showed an increased detection limit of up to 10(-8) M concentration of phosphate ion. The phosphate microsensor also showed its ability to measure sediment SRP profiling without disturbing sediment structure, and diffusion coefficients of phosphate in sediment could be determined under both oxic and anoxic conditions. Modified phosphate sensors showed improved sensitivity and could be applied to both water and sediment samples with high spatial resolution; however, signal interferences (especially with oxygen) required consideration during sample analysis. Overall, obtained results showed that phosphate microsensors can be an effective tool for measurement of phosphate in lake water and sediment samples for SRP monitoring. PMID:26156193

  10. 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. PMID:25041733

  11. Impact of urbanization on the concentrations and distribution of organic contaminants in boreal lake sediments.

    PubMed

    Honkonen, Olga; Rantalainen, Anna-Lea

    2013-02-01

    The main goal of this study was to evaluate the impacts of a middle-sized Finnish urban area on the quality of sediments in an adjacent boreal lake. We investigated the sources and distribution of organic pollutants (polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs)) in the sediments from urban stormwater traps and from Lake Vesijärvi. Grab surface sediment samples were taken from Lake Vesijärvi at various distances (25-2,000 m) from four major stormwater drainage outlets and at 15 urban stormwater traps in areas with different degrees of urbanization. These samples were analysed for 16 PAHs and 28 PCBs with gas chromatography-mass spectrometry. The concentrations of pollutants in the lake sediments were elevated in the vicinity of the urban shore (∑PAH 3-16, ∑PCB up to 0.02-0.3 mg/kg dw) and decreased as a function of distance (∑PAH 0.1-2.5, ∑PCB 0.01-0.3 mg/kg dw at a distance of more than 500 m from the shore), whereas contamination levels in suburban areas were notably lower (∑PAH 0.1-3, ∑PCB < LOQ-0.03 mg/kg dw; did not decline with distance). Possible sources and pathways of contamination were also investigated. The majority of stormwater trap sediments contained predominantly asphalt-derived PAHs due to pulverized pavement. PAHs in lake sediments were of pyrogenic origin, including the combustion of gasoline, diesel and coal. Suggested pathways of lake contamination are urban runoff discharge, boat traffic and atmospheric deposition. PMID:22527470

  12. Detection of recycled marine sediment components in crater lake fluids using 129I

    NASA Astrophysics Data System (ADS)

    Fehn, U.; Snyder, G. T.; Varekamp, J. C.

    2002-06-01

    Crater lakes provide time-integrated samples of volcanic fluids, which may carry information on source components. We tested under what circumstances 129I concentrations can be used for the detection of a signal derived from the recycling of marine sediments in subduction zone magmatism. The 129I system has been successfully used to determine origin and pathways in other volcanic fluids, but the application of this system to crater lakes is complicated by the presence of anthropogenic 129I, related to recent nuclear activities. Results are reported from four crater lakes, associated with subducting crust varying in age between 23 and 98 Ma. The 129I/I ratios determined for Copahue, Argentina, ( 129I/I=700×10 -15) and White Island, New Zealand, ( 129I/I=284×10 -15) demonstrate the presence of iodine in the crater lakes that was derived from recycled marine sediments. A comparison to the ages of the subducted sediments in these two cases indicates that the ratios likely reflect iodine remobilization from the entire sediment column that was undergoing subduction. While the 129I signals in Poás and Rincón de la Vieja, Costa Rica also demonstrate the presence of recycled iodine, the relatively high percentage of meteoric water in these lakes prevents a reliable determination of source ages. The observed high concentrations of iodine and 129I/I ratios substantially below current surface values strongly argue for the presence of recycled marine components in the arc magmas of all four cases. Components from subducted marine sediments can be quantified and related to specific parts of the sediment column in cases where the iodine concentration in the lake waters exceeds 5 μM.

  13. 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.

  14. 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

  15. 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...

  16. Depositional influences on porewater arsenic in sediments of a mining-contaminated freshwater lake.

    PubMed

    Toevs, Gordon; Morra, Matthew J; Winowiecki, Leigh; Strawn, Daniel; Polizzotto, Matthew L; Fendorf, Scott

    2008-09-15

    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. PMID:18853795

  17. 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.

  18. 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

  19. Modern sedimentation and varve formation processes in Lake Żabińskie, northeastern Poland

    NASA Astrophysics Data System (ADS)

    Bonk, Alicja; Tylmann, Wojciech; Enters, Dirk; Grosjean, Martin

    2014-05-01

    Lake Żabińskie is the main study site of CLIMPOL, a project which aims at establishing a quantitative reconstruction of climate change in northern Poland during the last millennium. The lake is located in the Masurian Lake District (54°07'54.5"N; 21°59'01.1"E) and presents features typical for kettle-hole lakes, i.e. a small surface area (41.6 ha) and a considerable depth (44.4 m) in the central part of the lake bottom. A set of gravity and piston cores collected from the deepest part of the lake indicate that the sediment record contains an undisturbed and continuous sequence of varved deposits. A regular monitoring of lake water properties and modern sedimentation was initiated to better understand the influences of limnology on the processes of varve formation and preservation in this lake. During monthly field campaigns a broad range of physical and chemical parameters of the lake water column as well as sediment fluxes were measured. Seasonal changes in sediment composition registered in sediment trap allow establishing documentation of an annual deposition model which is here compared with results of microstratigraphic investigations of thin sections and high-resolution XRF scanning of impregnated sediment slabs. Multiple calcite deposition during growing season of one year is well reflected in the complex structure of varves which include up to six individual calcite laminae. During spring and summer, pennate and centric diatoms occur in addition to calcite crystals. In the late summer grains of vivianite and pyrite are present. Chrysophyte cysts are also very common but no distinct seasonality can be observed. During autumn and winter period minerogenic and organic detritus occurs. XRF measurements confirm that highest Ca concentrations occur during spring and summer which are followed by distinct maxima in Fe, K and S concentrations. Si concentrations, which represent mainly biogenic silica content in the sediments are consistent with Ca while Mn

  20. Locating groundwater discharge in large lakes using bottom sediment electrical conductivity mapping

    NASA Astrophysics Data System (ADS)

    Harvey, F. Edwin; Lee, David R.; Rudolph, David L.; Frape, Shaun K.

    1997-11-01

    Groundwater-surface water studies that use conventional near-shore piezometers and /or seepage meters are impractical in larger, areal extensive lakes, as they require exorbitant numbers of instruments to quantify groundwater discharge zones. In smaller lakes an electrical conductivity mapping method has proven useful in mapping groundwater discharge zones. The technique identifies groundwater discharge by measuring variations in sediment pore water electrical conductivity and reduces the number of instruments necessary to quantify inflow, thereby lowering instrumentation costs and increasing a study's efficiency. This study sought to determine the technique's applicability in larger lakes. Thus the method was tested within the Hamilton Harbour, at the western end of Lake Ontario. This study found systematic variations between nearshore and offshore sediments and identified three anomalous zones that were thought to represent groundwater inflow. Onshore and offshore piezometers were used to verify the presence of upward gradients and elevated electrical conductivities. The sediment probe survey provided qualitative maps of areas of elevated electrical conductivity indicative of groundwater discharge and allowed a fairly extensive shoreline to be mapped quickly and economically. Survey results guided the installation of nearshore piezometers to discharge zones, eliminating the inefficiency of more conventional "hit or miss" point source installation approaches. This research demonstrated that the sediment probe was a valuable tool for studying groundwater inputs into large lakes.

  1. 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.

  2. 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

  3. 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...

  4. Impact of the 2013 summer flood on hydrological processes and sediment transport in Lake Mondsee and its catchment (Austria)

    NASA Astrophysics Data System (ADS)

    Mueller, P.; Kaempf, L.; Guntner, A.; Brauer, A.; Merz, B.

    2013-12-01

    One crucial limitation in the field of flood frequency analysis is the availability of long instrumental flood time series. Geoarchives such as lake sediments record land surface processes including extreme events and are used to elongate instrumental time series to geological time scales. A seasonally resolved flood layer chronology over the past 7000 years has already been established from varved lake sediments of Lake Mondsee (Upper Austria). The interpretation of lacustrine flood layer chronologies, however, requires detailed understanding of hydro-sedimentary processes during floods, including the transformation of the rain event into discharge and sediment dynamics from the catchment's source areas until the deposition within the lake. For this purpose, flood and sediment transport related variables like precipitation, runoff and suspended sediment concentration are monitored at five gauges in the Fuschler Ache river catchment, the largest sub-catchment draining to Lake Mondsee. These gauges cover the catchment from the headwaters to the outlet into Lake Mondsee. Lake monitoring is realized by implementing four buoys and two multi-level sediment traps. Meteorological and limno-physical variables measured at each buoy with 15 minute resolution are turbidity as surrogate for suspended sediment concentration, water temperature and flow velocity in different water depths as well as wind, air temperature and relative humidity. The monitoring system provided a unique data set for the extreme summer flood in June 2013. The data show the stream response to an extreme rainfall event, processes and rates of sediment transport in the catchment and sediment dynamics and sedimentation rates within the lake. A comparison of the 2013 summer event to past severe flood events in the Lake Mondsee catchment elucidates the need of detailed process understanding of the catchment processes and the lake-internal processes to properly interpret flood chronologies derived from

  5. Mercury in sediment, water, and fish in a managed tropical wetland-lake ecosystem.

    PubMed

    Malczyk, Evan A; Branfireun, Brian A

    2015-08-15

    Mercury pollution has not been well documented in the inland lakes or fishes of Mexico, despite the importance of freshwater fish as a source of protein in local diets. Total mercury and methylmercury in waters, sediments, and the commercial fish catch were investigated in Lake Zapotlán, Mexico. Concentrations of total and methylmercury were very high in runoff and wastewater inputs, but very low in sediments and surface waters of the open water area of the lake. Concentrations of total mercury in tilapia and carp were very low, consistent with the low concentrations in lake water and sediments. Particle settling, sorption, the biogeochemical environment, and/or bloom dilution are all plausible explanations for the significant reductions in both total mercury and methylmercury. Despite very high loading of mercury, this shallow tropical lake was not a mercury-impaired ecosystem, and these findings may translate across other shallow, alkaline tropical lakes. Importantly, the ecosystem services that seemed to be provided by peripheral wetlands in reducing mercury inputs highlight the potential for wetland conservation or restoration in Mexico. PMID:25909268

  6. Isotope Record of Anthropogenic Lead Pollution in Lake Sediments of Florida, USA

    NASA Astrophysics Data System (ADS)

    Escobar, J.; Whitmore, T.; Kamenov, G. D.; Riedinger-Whitmore, M.

    2013-05-01

    We looked at the anthropogenic lead (Pb) burden that accumulated in sediment of lakes in the southeastern USA during the last century. Few studies have examined Pb in lakes of the southeastern USA, which is subject to less continental atmospheric influence than other regions of the eastern USA. The sediment records from Little Lake Jackson and Little Lake Bonnet showed that changes in Pb concentration and isotope ratios correspond temporally with gasoline consumption in the USA, as well as with changes in lead ores used to produce leaded gasoline. Lead concentrations in the study lakes showed temporal variations that were similar to those found in peat records from east-central Florida. Isotope trends were similar to the mean USA atmospheric Pb deposition record, and to Pb isotope records from Bermuda and Atlantic corals. We modeled the isotopic composition of the anthropogenic Pb in lake sediments and found that the overall trend is controlled by Pb that was released during leaded gasoline combustion. There is, however, additional Pb at each site that comes from sources that are not fully represented by the natural, background Pb.

  7. 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

  8. 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.

  9. 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.

  10. 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

  11. Contamination and Risk Assessment of Heavy Metals in Lake Bed Sediment of a Large Lake Scenic Area in China.

    PubMed

    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

  12. 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

  13. 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.

  14. A holocene perspective on algal mercury scavenging to sediments of an Arctic lake.

    PubMed

    Cooke, Colin A; Wolfe, Alexander P; Michelutti, Neal; Balcom, Prentiss H; Briner, Jason P

    2012-07-01

    Anthropogenic activities have increased the amount of mercury (Hg) transported atmospherically to the Arctic. At the same time, recent climate warming is altering the limnology of arctic lakes and ponds, including increases in aquatic primary production. It has been hypothesized that climate-driven increases in aquatic production have enhanced Hg scavenging from the water column, and that this mechanism may account for much of the recent rise in lake sediment Hg. Here, we test the relationship between climate, algal production, and sediment Hg using a well-dated and multiproxy lake sediment record spanning the Holocene from Lake CF3 (Baffin Island, Nunavut, Canada). During the early Holocene, peak (summer) insolation drove July air temperatures higher than present, and resulted in increased autochthonous primary production as recorded by total organic matter, spectrally inferred Chl-a, diatom abundance, and carbon stable isotopic signatures. However, there are no relationships between any of these proxies and sediment Hg concentrations during this interval. Given that the behavior of preindustrial Hg was relatively stable during past intervals of naturally mediated high production, we surmise that postindustrial increases in Hg accumulation within CF3 reflect a multiplicative effect of atmospheric deposition of anthropogenic Hg and increased sedimentation rates. PMID:22687141

  15. An assessment of leaf wax hydrogen isotopes as a climate proxy in proglacial arctic lake sediments

    NASA Astrophysics Data System (ADS)

    Thomas, E. K.; Huang, Y.; Briner, J. P.; McGrane, S.

    2010-12-01

    High-resolution (sub-decadal), Holocene quantitative climate records can be difficult to obtain from lakes in the arctic. Varved lake sediments, which yield annual climate records, rarely extend beyond the past millennium. Paleoecological-based climate reconstructions (e.g., from pollen and chironomid taxa) are time-consuming to obtain, require large amounts of sediment, and in some cases do not respond at high-resolution time scales (e.g., pollen). Therefore, sub-decadally resolved ecological records can be produced only from organic-rich sediments with very high sedimentation rates, which is uncommon in most of the arctic. Compound-specific isotopes of leaf waxes are more rapid to measure and require less sediment than many other climate proxies. Furthermore, current analytical abilities detect measurable concentrations of leaf waxes even in mineral-rich proglacial lake sediments. Proglacial lakes have orders of magnitude higher sedimentation rates than non-glacial lakes, and thus offer great potential for novel, high-resolution arctic climate records. Here, we isolate and analyze leaf wax (n-acid) hydrogen isotope ratios (δDlw) from sediments from three proglacial lakes on Baffin Island, Arctic Canada. Leaf waxes reflect δDprecip, which is controlled by several factors including temperature and precipitation source area. Although extensive work has been conducted on leaf wax isotopes as a climate proxy at low latitudes, there has been much less research near the poles. We analyzed samples at three different resolutions: one lake at annual or biennial resolution (from varved sediments) spanning the past 50 years, one at sub-centennial resolution spanning the past 2.5 kyr, and the last at sub-millennial resolution spanning the past 8 kyr. We compare each of these records to existing regional instrumental and reconstructed climate records. On the millennial scale, δDlw is more enriched when glacier extent was smaller during the middle Holocene, indicating that

  16. 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

  17. A sediment budget for southern Lake Michigan: source and sink models for different time intervals

    USGS Publications Warehouse

    Colman, Steven M.; Foster, D.S.

    1994-01-01

    Two terms dominate the modern sediment-budget equation: (1) bluff erosion, which is an order of magnitude larger than either rivers or aerosols as a source, and (2) deposition in the deep basin, which is more than two orders of magnitude greater as a sink than suspended sediment transport out of the basin. The attempt to reconstruct sediment budgets for time intervals of 100, 5000, and 10 000 years leads to important insights about erosion and sedimentation processes. Bluff erosion is the dominant source of both sand and mud in the basin. The deep lake floor is the primary sink for mud, whereas both the deep lake and nearshore areas are important sinks for sand. -from Authors

  18. 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.

  19. Longevity and effectiveness of aluminum addition to reduce sediment phosphorus release and restore lake water quality.

    PubMed

    Huser, Brian J; Egemose, Sara; Harper, Harvey; Hupfer, Michael; Jensen, Henning; Pilgrim, Keith M; Reitzel, Kasper; Rydin, Emil; Futter, Martyn

    2016-06-15

    114 lakes treated with aluminum (Al) salts to reduce internal phosphorus (P) loading were analyzed to identify factors driving longevity of post-treatment water quality improvements. Lakes varied greatly in morphology, applied Al dose, and other factors that may have affected overall treatment effectiveness. Treatment longevity based on declines in epilimnetic total P (TP) concentration averaged 11 years for all lakes (range of 0-45 years). When longevity estimates were used for lakes with improved conditions through the end of measurements, average longevity increased to 15 years. Significant differences in treatment longevity between deeper, stratified lakes (mean 21 years) and shallow, polymictic lakes (mean 5.7 years) were detected, indicating factors related to lake morphology are important for treatment success. A decision tree developed using a partition model suggested Al dose, Osgood index (OI, a morphological index), and watershed to lake area ratio (related to hydraulic residence time, WA:LA) were the most important variables determining treatment longevity. Multiple linear regression showed that Al dose, WA:LA, and OI explained 47, 32 and 3% respectively of the variation in treatment longevity. Other variables (too data limited to include in the analysis) also appeared to be of importance, including sediment P content to Al dose ratios and the presence of benthic feeding fish in shallow, polymictic lakes. PMID:26250754

  20. Lake Biel Holocene sediment record before and after the Aare river deviation (1878 AD)

    NASA Astrophysics Data System (ADS)

    Jeannet, Alice; Corella, Juan Pablo; Kremer, Katrina; Girardclos, Stéphanie

    2014-05-01

    Lake sediments are excellent archives of environmental and climate changes as well as human impact on lake- and river-systems. Lake Biel is a medium-sized peri-alpine lake in Switzerland, with a maximum depth of 74 m, and lies at an altitude of 429 m a.s.l. Lake Biel, which formed during the Pleistocene by glacial erosion, is part of the Aare river system. Our study focuses on the south-west part of the lake basin where the lake sedimentation was originally (i.e. naturally) mainly controlled by autochthonous sedimentation. This area is currently under a strong influence of water and sediment input from this river catchment since the Aare river deviation through the Hagneck canal in 1878. A 10.05 m long composite sediment sequence, cored from a 52 m water depth in September 2011, was built from two long cores retrieved with the ETH Zurich/Eawag Uwitec system. A radiocarbon age model indicates that the retrieved sedimentary sequence spans the last 7500 years. The upper sediments were correlated to previous short core radionuclide stratigraphy for the 1.5 m upper part (Thevenon et al., 2013). Magnetic susceptibility and density were measured by Geotek MultiSensor Core Logger at 0.5 cm resolution. Granulometry was measured with a CILAS grain sizer every 10 cm, and X-ray fluorescence (XRF) was carried out using an Avaatech core scanner at 1-cm resolution. This technique provides semi-quantitative information of the sediment elemental composition and shows how runoff and river input (Ti, Al, Si) or redox conditions (Fe/Mn) vary through time. Lake Biel sediment record suggests marked environmental changes with runoff decrease linked to climate and vegetation change during Atlantic chronobiozone, as well as a complex climate-human impact during the 'La Tène' and Roman cultural times. The most prominent recorded feature is the 10-times increase of sediment rate that occurred after the Aare river deviation through the Hagneck canal into Lake Biel in 1878. This artificial

  1. 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

  2. Comparative aspects of sulfur mineralization in sediments of a eutrophic lake basin.

    PubMed

    King, G M; Klug, M J

    1982-06-01

    The net mineralization of organic sulfur compounds in surface sediments of Wintergreen Lake was estimated from a mass-balance budget of sulfur inputs and sediment sulfur concentrations. The net mineralization of organic sulfur inputs is <50% complete, which is consistent with the dominance of organic sulfur (>80% of total sulfur) in sediment. Although sediment sulfur is predominantly organic, sulfate reduction is the most significant process in terms of the quantities of sulfur transformed in surface sediments. Rates of sulfate reduction in these sediments average 7 mmol/m per day. On an annual basis, this rate is 19-fold greater than net rates of organic sulfur mineralization and 65-fold greater than sulfate ester hydrolysis. PMID:16346037

  3. 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.

  4. 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

  5. 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

  6. 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.

  7. 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.

  8. 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. PMID:19399548

  9. Distribution of total mercury and methylmercury in lake sediments in Arctic Ny-Ålesund.

    PubMed

    Jiang, Shan; Liu, Xiaodong; Chen, Qianqian

    2011-05-01

    The toxicities and bioavailabilities of total mercury (THg) and methylmercury (MeHg) in aquatic systems have made them the subjects of recent research. In this study, we collected a lake sediment core from Ny-Ålesund in Svalbard and analyzed the distributions of THg and MeHg in the sediments. The increased trend of THg was caused by anthropogenic contamination since the 14th century through long-range transportation, especially after the industrial era. However, the peak values of Hg in surface sediment samples could be explained by the increased algal scavenging process in recent decades. All the biogeochemical proxies (e.g., pigments and diatom biomass) revealed recent sharp increases in aquatic primary production due to the current climate warming. Rock-Eval analyses indicated that algal-derived organic matter took up a large portion, and quantitative calculation showed that 89.6-95.8% of the Hg in post-1950 could be explained by scavenging. The distribution of MeHg has a close relationship with total Hg and organic matter. The oxidation-reduction condition is one of the possible factors affecting the methylation rates in H2 lake sediments. Higher algal productivity and organic matter actually led to the increased trend of methylation in the uppermost sediment. This study supports some new key hypotheses on climate-driven factors affecting Hg and MeHg cycling in High Arctic lake sediments. PMID:21306754

  10. 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.

  11. 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.

  12. The Effect of Sediment Disturbance on the Carbon and Nitrogen Cycles Within Coastal Marine Lakes

    NASA Astrophysics Data System (ADS)

    Mills, A. R.; Wilson, S. R.; Jolley, D. F.

    2006-12-01

    A system allowing the ex situ quantification of the nitrogen cycle and various carbonaceous species (Organic Carbon, carbon dioxide, methane) in the air, water and sediment has been developed and used to monitor the effects of sediment disturbance on the nitrogen and carbon cycles. Measurements are made using standard wet chemical techniques for the sediment and water phases, and FTIR spectroscopy for the real-time monitoring of gas concentrations. Sediment collected from two temperate marine lakes on the eastern coast of Australia has been examined. In the laboratory it was found that the methane flux peaked three days after the initial disturbance; nitrous oxide flux peaked after 12 days while carbon dioxide flux varied throughout the experiment. Nitrite and nitrate concentrations in the overlying water peaked at the end of the second and third weeks, respectively. The total quantity of nitrogen within the system increased by ~ 35%. Sediment disturbance led to an initial release of nitrogenous nutrients from the sediment to the overlying water that were rapidly readsorbed to sediment particles and sequestered back into the sediment phase. The same technology was also adapted to allow this research to be undertaken in the field and used to study three new temperate marine sites within Lake Illawarra, New South Wales, Australia.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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

  19. 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.

  20. Heavy metals in Lake Balaton: water column, suspended matter, sediment and biota.

    PubMed

    Nguyen, H L; Leermakers, M; Osán, J; Török, S; Baeyens, W

    2005-03-20

    During the period 1999-2002, five sampling cruises have been carried out on Lake Balaton to assess trace metal distribution in the lake and to identify major sources. Eighteen elements, including Cr, Co, Ni, Cu, Zn, Cd, Pb (trace metals) and Al, Ba, Ca, Fe, K, Mg, Mn, Na, P, S, Sr (major metals), were determined in one or more of the lake's compartments. Lower trace metal concentrations in rainwater were observed in June and February 2000, while much higher levels were present in September 2001 (during a storm event) and in snow (February 2000). In the Northern and Western parts of the lake, especially at the inflow of river Zala and the locations of the yacht harbours, metal concentrations were higher in almost all compartments. Because the lake is very shallow, storm conditions also change significantly the metal distributions in the dissolved and particulate phases. The Kis-Balaton protection system located on Zala river functions very efficiently for retaining suspended particulate matter (SPM; 72% retention) and associated metals. Metal concentrations in surface sediments of the lake showed a high variability. After normalisation for the fine sediment fraction, only a few stations including Zala mouth appeared to be enriched in trace metals. In zooplankton, Zn seemed to be much more elevated compared to the other trace metals. Based on the molar ratios of the trace metals in the various compartments and input flows of the lake, several trends could be deduced. For example, molar ratios of the trace metals in the dissolved and solid (suspended particulate matter and sediments) phases in the lake are fairly similar to those in Zala River. PMID:15752503

  1. 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.

  2. Physical and chemical characteristics of the Subglacial Lake Whillans sediment cores, Whillans Ice Stream, West Antarctica

    NASA Astrophysics Data System (ADS)

    Hodson, T. O.; Powell, R. D.

    2013-12-01

    Sediment recovered from Subglacial Lake Whillans (SLW) is well-homogenized, structureless diamict; typical subglacial till. Based on theoretical estimates, the basal ice above SLW should be below the pressure melting point preventing melt-out of debris from basal ice. Therefore, the lake floor diamict likely formed through deformation while the ice stream was grounded at the drill site. Using satellite altimetry, Fricker, et al. (2007) inferred that SLW experiences short (~7 month) discharge events, lowering the ice surface and lake water level by between 1 and 4 m. The lake 'lowstands' are separated by longer periods of gradual recharge, but over the period of a lowstand the ice stream is suspected to touch down and couple with the lake floor, potentially shearing new till into the lake. The lack of sorted sediment or erosional lags indicates water flow during discharge/recharge events has had a low current velocity with quiescent conditions in the lake. The most notable variability in the cores is a uniformly weak, critical porosity horizon extending to ~50 cm depth above more consolidated till. We interpret the weak upper horizon as the product of shear deformation and decreasing effective pressure experienced during the final stages of grounding prior to a lake recharge event (see generally, the undrained plastic bed model of Tulaczyk et al. (2000)). The presence of this weak layer illustrates the importance of hydrology in modulating till rheology and is an example of how subglacial sediments can preserve archives of hydrologic conditions at the glacial bed. Fricker, H.A., T. Scambos, R. Bindschadler and L. Padman. 2007. An active subglacial water system in West Antarctica mapped from space. Science, 315(5818), 1544-1548. Tulaczyk S, Kamb WB, Engelhardt HF. 2000. Basal mechanics of Ice Stream B, West Antarctica. 2. Undrained plastic bed model. J. Geophys. Res. 105:483-94.

  3. PETROLEUM HYDROCARBONS IN SEDIMENTS OF SAGINAW BAY, LAKE HURON

    EPA Science Inventory

    The history of petroleum contamination of Saginaw Bay is given by a 60 cm core recording sediment accumulation over the last two centuries. Aliphatic hydrocarbon concentrations average 385 micrograms/gm in modern sediments and progressively decrease from 10 cm to 40 cm in the cor...

  4. 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.

  5. 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. PMID:27090527

  6. 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.

  7. 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

  8. 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

  9. Hydrology of Lake Butler, Orange County, Florida

    USGS Publications Warehouse

    Smoot, James L.; Schiffer, Donna M.

    1984-01-01

    Lake Butler is one of the lakes that collectively make up the Butler chain of lakes in the headwaters of the Kissimmee River, Florida. The bottom configuration of the lake is typical of relict karst features formed during lower stages in sea level. The top of the Floridan aquifer is 50 to 100 feet below the land surface. The drainage area of Lake Butler is approximately 14.5 sq mi and is comprised of sub-basins of other lakes in the vicinity. Surface outflow from Lake Butler is generally southward to Cypress Creek, a tributary of the Kissimmee River. The extremes in lake stage for the period 1933-81 are 94.67 ft on June 23, 1981 and 101.78 ft on September 13, 1960. The median lake stage for this period was 99.28 ft above sea level. The quality of water in Lake Butler is excellent, based on studies of physical, chemical, and biological conditions by the Orange County Pollution Control Department. The lake water is slightly acidic and soft (48 mg/L hardness as calcium carbonate). Pesticides in water were below detection levels at two sites sampled in the lake, but were detected in the bottom sediments. (USGS)

  10. 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

  11. 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

  12. 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

  13. 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.

  14. 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. PMID:26895174

  15. 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

  16. 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

  17. 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.

  18. 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.

  19. 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

  20. Ecosystem regime change inferred from the distribution of trace metals in Lake Erie sediments.

    PubMed

    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

  1. 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 ...

  2. Chlorine-36 dating of saline sediments: Preliminary results from Searles Lake, California

    USGS Publications Warehouse

    Phillips, F.M.; Smith, G.I.; Bentley, H.W.; Elmore, D.; Gove, H.E.

    1983-01-01

    Measurements have been made of the ratios of chlorine-36 to chlorine in five halite samples from Searles Lake sediments, previously dated by carbon-14, thorium-230, and magnetostratigraphic techniques. The ages calculated from the chlorine ratios are generally concordant with those from the other methods, implying the constancy of the chlorine input ratio over the last million years.

  3. Spatial distribution and sources of organic carbon in the surface sediment of the Bosten Lake, China

    NASA Astrophysics Data System (ADS)

    Yu, Z. T.; Wang, X. J.; Zhang, E. L.; Zhao, C. Y.; Lan, H. Y.

    2015-08-01

    Lake sediment is an important carbon reservoir. However, little is known on the dynamics and sources of sediment organic carbon in the Bosten Lake. We collected 13 surface (0-2 cm) sediment samples in the Bosten Lake and analyzed total organic carbon (TOC), total nitrogen (TN), stable carbon isotopic composition in TOC (δ13Corg) and grain size. We found a large spatial variability in TOC content (1.8-4.4 %) and δ13Corg value (-26.77 to -23.98 ‰). Using a three end member mixing model with measured TOC : TN ratio and δ13Corg, we estimated that 54-90 % of TOC was from autochthonous sources. Higher TOC content (> 3.7 %) was found in the east and central-north sections and near the mouth of the Kaidu River, which was attributable to allochthonous, autochthonous plus allochthonous, and autochthonous sources, respectively. The lowest TOC content was found in the mid-west section, which might be a result of high kinetic energy levels. Our study indicated that the spatial distribution of sediment TOC in the Bosten Lake was influenced by multiple and complex processes.

  4. Spatial distribution and sources of organic carbon in the surface sediment of Bosten Lake, China

    NASA Astrophysics Data System (ADS)

    Yu, Z. T.; Wang, X. J.; Zhang, E. L.; Zhao, C. Y.; Liu, X. Q.

    2015-11-01

    Lake sediment is an important carbon reservoir. However, little is known on the dynamics and sources of sediment organic carbon in Bosten Lake. We collected 13 surface (0-2 cm) sediment samples in Bosten Lake and analyzed total organic carbon (TOC), total nitrogen (TN), stable carbon isotopic composition in TOC (δ13Corg), and grain size. We found a large spatial variability in TOC content (1.8-4.4 %) and δ 13Corg value (-26.77 to -23.98 ‰). Using a three-end-member mixing model with measured TOC : TN ratio and δ13Corg, we estimated that 54-90 % of TOC was from autochthonous sources. Higher TOC content (> 3.7 %) was found in the east and central-north sections and near the mouth of the Kaidu River, which was attributable to allochthonous, autochthonous plus allochthonous, and autochthonous sources, respectively. The lowest TOC content was found in the mid-west section, which might be a result of high kinetic energy levels. Our study indicated that the spatial distribution of sediment TOC in the Bosten Lake was influenced by multiple and complex processes.

  5. 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. PMID:27176930

  6. 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...

  7. Spatial and temporal trends in surface water and sediment contamination in the Laurentian Great Lakes.

    PubMed

    Marvin, Chris; Painter, Scott; Williams, Donald; Richardson, Violeta; Rossmann, Ronald; Van Hoof, Patricia

    2004-05-01

    Data from recent sediment and surface water surveys have been collated and mapped to illustrate the spatial distribution of contaminants across the entire Great Lakes basin. Information from historical surveys, together with data from surface water monitoring programs in three major connecting channels, has also been collated in order to evaluate temporal trends. In general, Lakes Superior and Michigan exhibited the lowest levels of sediment contamination while Lake Ontario had the highest. Contaminants such as gamma-HCH (lindane) and dieldrin were ubiquitous in surface waters across the entire basin, which was indicative of atmospheric sources. The distribution of other compounds including hexachlorobenzene, octachlorostyrene and mirex indicated the presence of local sources within the watersheds of the connecting channels. Surficial sediment contamination was found to have decreased markedly since the late 1960s and 1970s. Similarly, surface water contamination decreased over the period 1986-1997 with concentrations of dieldrin, hexachlorobenzene, octachlorostyrene and mirex reduced by over 50%. However, the spatial distributions of both sediment and surface water contamination indicate that further effort is warranted in reducing local sources of contaminants, particularly in Lake Ontario. PMID:14749077

  8. OVERVIEW OF USEPA/CLEAR LAKE ERIE - SEDIMENT OXYGEN DEMAND INVESTIGATIONS DURING 1979

    EPA Science Inventory

    In situ hypolimnetic oxygen depletion measurements were conducted during four summer cruises in 1979 at two central basin stations in Lake Erie to evaluate the relative contribution of the sediments to the oxygen demand. ediment oxygen demand (SOD) rates were determined by measur...

  9. Draft genome sequences of five new strains of methylophilaceae isolated from lake washington sediment.

    PubMed

    McTaggart, Tami L; Benuska, Gabrielle; Shapiro, Nicole; Woyke, Tanja; Chistoserdova, Ludmila

    2015-01-01

    We sequenced the genomes of five new Methylophilaceae strains isolated from Lake Washington sediment. We used the new sequences to sort these new strains into specific Methylophilaceae ecotypes, including one novel ecotype. The new genomes expand the known diversity of Methylophilaceae and provide new models for studying the ecology of methylotrophy. PMID:25657279

  10. Draft Genome Sequences of Five New Strains of Methylophilaceae Isolated from Lake Washington Sediment

    PubMed Central

    McTaggart, Tami L.; Benuska, Gabrielle; Shapiro, Nicole; Woyke, Tanja

    2015-01-01

    We sequenced the genomes of five new Methylophilaceae strains isolated from Lake Washington sediment. We used the new sequences to sort these new strains into specific Methylophilaceae ecotypes, including one novel ecotype. The new genomes expand the known diversity of Methylophilaceae and provide new models for studying the ecology of methylotrophy. PMID:25657279

  11. 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.

  12. ENANTIOSELECTIVE REDUCTIVE TRANSFORMATION OF CHIRAL POLYCHLORINATED BIPHENYLS IN LAKE SEDIMENT MICROCOSMS

    EPA Science Inventory

    The transformation rates and enantiomeric ratios of two chiral poylchlorinated biphenyls (PCBs), 2,2',3,4',5',6-hexachlorobiphenyl (2,2',3,4',5',6-HCB) and 2,2',3,3',4,4',5,6-octachlorobiphenyl (2,2',3,3',4,4',5,6-OCB), were determined in anaerobic lake sediment microcosms (25oC)...

  13. Chemical indicators of anthropogenic impacts in sediments of the pristine karst lakes.

    PubMed

    Mikac, I; Fiket, Z; Terzić, S; Barešić, J; Mikac, N; Ahel, M

    2011-08-01

    The anthropogenic impact on the pristine karst lakes was investigated using combination of specific parameters, including multielemental analysis of major inorganic constituents (Al, K, Fe) and trace metals (Li, Ag, Cd, Sn, Pb, Bi, Cr, Co, Ni, Cu, Zn and Sb), polycyclic aromatic hydrocarbons (PAHs) and anionic surfactants of linear alkylbenzene sulfonate (LAS) type. The study was performed in the Plitvice Lakes National Park, situated in a sparsely populated area of the northwestern Dinarides, central Croatia. Dated cores of recent sediments from the two biggest lakes, Lake Prosce and Lake Kozjak, were analysed for the selected contaminants using highly specific methods, involving inductively coupled plasma mass spectrometry (ICP/MS), gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS). The concentration of inorganic constituents reflected primarily the geological background of the area as well as geomorphological and geochemical characteristics of the Plitvice Lakes. Due to the higher terrigenous input, the concentration of all elements was significantly higher in the Lake Prosce. The concentration of toxic metals was relatively low in both lakes, except for Cd (>1 mg kg(-1)) and Pb (up to 40 mg kg(-1)). The vertical profiles of these metals suggested that elevated concentrations of Cd were of natural origin, derived from the erosion of the Jurassic dolomite bedrock, while Pb was predominately of recent anthropogenic origin. A similar distribution pattern, suggesting the same prevailing mechanism of input, was observed for pyrolytic PAHs. The characteristic diagnostic PAH ratios revealed that higher PAHs prevailingly originated from the combustion of biomass and fossil fuels. LAS, which represent highly specific indicators of untreated wastewaters, were found in rather high concentrations in the recent sediment layers (up to 4.7 mg kg(-1)), suggesting that contaminated household and hotel wastewaters reach the

  14. Last Interglacial climate variability recorded in sediments of Lake Ohrid (Albania/Macedonia)

    NASA Astrophysics Data System (ADS)

    Vogel, H.; Valsecchi, V.; Schouten, S.; Leng, M. J.; Wagner, B.; Sulpizio, R.; Zanchetta, G.; Lotter, A. F.

    2010-12-01

    Lake Ohrid, a transboundary lake shared by the former Yugoslav Republic of Macedonia and the Republic of Albania is with its likely Pliocene age considered to be the oldest existing lake in Europe. Since 2004 several sediment successions have been recovered from Lake Ohrid. The longest records cover the last glacial-interglacial cycle and reach back to MIS 6. Independent age control is given by radiocarbon dating and tephrochronology. These records allow insights on climatic and environmental evolution of the last interglacial in a region, which today is densely populated and highly vulnerable to climate change. We used a multiproxy approach to study climatic and environmental variability during the last interglacial. This approach combines novel molecular (TEX86, MBT/CBT) and established sedimentological, geochemical and paleoecological tools. These combined data imply that the last interglacial at Lake Ohrid was preceded by an interstadial period between c. 133 and 131 ka that was followed by a stadial centred at c. 130 ka and characterized by a marked vegetation shift to more steppic elements around the lake. Subsequently, temperatures rose steadily from c. 129 to 122 ka. From c. 122 ka temperatures declined gradually. A sudden drop in temperatures starting at about 116 ka probably marks the end of the last interglacial period at Lake Ohrid. A comparison of highest temperatures during the Holocene and the last interglacial points to 2-3 °C higher temperatures during the last interglacial. A temperature increase in the same order is predicted by climate models for this region implying that last interglacial climatic and environmental conditions as recorded in Lake Ohrids sediments could provide a relatively good analogue for the future. However, longer records from this area are needed to gain a better understanding of natural climate variability during interglacials with a different setting of orbital parameters. In order to recover longer records extending

  15. 10Be in Lake Lisan sediments — A proxy for production or climate?

    NASA Astrophysics Data System (ADS)

    Belmaker, Reuven; Lazar, Boaz; Tepelyakov, Natalya; Stein, Mordechai; Beer, Jürg

    2008-05-01

    The geochemical behavior of 10Be in the modern Dead Sea hydrological-limnological system was studied in order to evaluate the feasibility of using Dead Sea and Lake Lisan (the late Pleistocene precursor of the Dead Sea) sediments as archives of the variations in the 10Be production rate. 10Be concentrations in detrital and aragonite material from Lake Lisan laminated sediments were compared to those measured in modern dust, terra rossa soil (aeolian in origin), loess from the Negev Desert, flood suspended load and waters along a rain-flood development pathway (the transition from rain to incipient runoff and fully developed floods). 10Be concentrations decreased throughout the flood development profile, from 8.2 × 10 3 atoms g - 1 in the runoff down to ~ 1 × 10 3 atoms g - 1 in Dead Sea brine due to fast removal of 10Be by the soil and dust particles. Thus, most of the 10Be in the lake is contained within the detrital sediments that collect the 10Be transported by particles from the surrounding terrain (e.g. desert dust with 1.6 ± 0.8 × 10 8 atoms g - 1 and terra rossa soil-material with up to 12.5 ± 0.5 × 10 8 atoms g - 1 ). The high-stand periods of Lake Lisan were characterized by annual deposition of silty-detritus sediments reflecting rapid transfer of desert dust to the lake by floods. Indeed, the bulk sediments of Lake Lisan (in which 10Be is associated mainly with silty-detritus) display 10Be concentrations similar to those of desert dust. This demonstrates that 10Be variations were modulated by climate (i.e., particle transport). Significant positive 10Be peaks (up to 1.6 × 10 8 atoms g - 1 ) appear during intervals of geomagnetic anomalies in Lake Lisan stratigraphy and in the global record (i.e. during the Laschamp geomagnetic event at ~ 41 ka BP). This indicates that 10Be atmospheric production signal is superimposed on the climatic 10Be variations. We conclude that after "de-trending" of the climatic signal, Lake Lisan sediments may be used as

  16. 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. PMID:24487920

  17. Sediment core fossils in ancient Lake Ohrid: testing for faunal change since the Last Interglacial

    NASA Astrophysics Data System (ADS)

    Albrecht, C.; Vogel, H.; Hauffe, T.; Wilke, T.

    2010-11-01

    Ancient Lake Ohrid is probably of early Pleistocene or Pliocene origin and amongst the few lakes in the world harbouring an outstanding degree of endemic biodiversity. Although there is a long history of evolutionary research in Lake Ohrid, particularly on molluscs, a mollusc fossil record has been missing up to date. For the first time, gastropod and bivalve fossils are reported from the basal, calcareous part of a 2.6 m long sediment succession (core Co1200) from the north-eastern part of Lake Ohrid. Electron spin resonance (ESR) dating of mollusc shells from the same stratigraphic level yielded an age of 130 ± 28 ka. Lithofacies III sediments, i.e. a stratigraphic subdivision comprising the basal succession of core Co1200 between 181.5-263 cm, appeared solid, greyish-white, and consisted almost entirely of silt-sized endogenic calcite (CaCO3>70%) and intact and broken mollusc shells. Here we compare the faunal composition of the thanatocoenosis with recent mollusc associations in Lake Ohrid. A total of 13 mollusc species (9 gastropod and 4 bivalve species) could be identified within Lithofacies III sediments. The value of sediment core fossils for reconstructing palaeoenvironmental settings was evaluated and the agreement between sediment and palaeontological proxies was tested. The study also aims at investigating major faunal changes since the Last Interglacial and searching for signs of extinction events. The combined findings of the ecological study and the sediment characteristics suggest deposition in a shallow water environment during the Last Interglacial. The fossil fauna exclusively included species also found in the present fauna, i.e. no extinction events are evident for this site since the Last Interglacial. The thanatocoenosis showed the highest similarity with recent Intermediate Layer (5-25 m water depth) mollusc assemblages. The demonstrated existence of a mollusc fossil record in Lake Ohrid sediment cores also has great significance for future

  18. Lake sediment records of late Holocene monsoon variability in western Nepal (preliminary results)

    NASA Astrophysics Data System (ADS)

    Ghazoui, Zakaria; Bertrand, Sebastien; Sachse, Dirk; Nomade, Jerome; Prasad Gajurel, Ananta; van der Beek, Peter

    2015-04-01

    In Nepal, high altitude paleoclimatological and limnological studies face many logistical challenges due to remoteness, accessibility, and altitude of potential lake sampling sites. Therefore, paleolimnological investigations in the Nepalese Himalaya remain scarce, and most of our understanding of past Indian Summer Monsoon (ISM) variability relies on a low-density network of speleothems and ice cores. Here we report preliminary new data from three high-altitude lakes in the Nepal Himalaya. In order to improve our understanding of climate variability in western Nepal during the late Holocene three lakes were investigated and sampled in autumn 2014: Rara Lake, Mugu District; Phoksundo Lake, Dolpa District; Dhumba Lake, Mustang District. The sediment cores are being studied using a multi-proxy approach combining radiocarbon, 210Pb and 137Cs chronologies, physical properties (Geotek multi-sensor core logger), grain size (Malvern Mastersizer 3000) inorganic geochemistry (major and selected trace elements by ICP-AES and ITRAX XRF core scanning), bulk organic geochemistry (C, N concentrations and stable isotopes) and hydrogen isotopic composition of leaf wax long-chain n-alkanes (δDwax). These sediment records will provide important new insights into the late-Holocene variability of the Indian Summer Monsoon in Nepal, including the recent latitudinal shift of the rainbelt due to climate change in the 20th and 21st centuries.

  19. 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.

  20. Trends in metals in urban and reference lake sediments across the United States, 1970 to 2001

    USGS Publications Warehouse

    Mahler, B.J.; Van Metre, P.C.; Callender, E.

    2006-01-01

    Trends in metals concentrations in sediment cores from 35 reservoirs and lakes in urban and reference settings were analyzed to determine the effects of three decades of legislation, regulation, and changing demographics and industrial practices in the United States on concentrations of metals in the environment. Decreasing trends outnumber increasing trends for all seven metals analyzed (Cd, Cr, Cu, Pb, Hg, Ni, and Zn). The most consistent trends are for Pb and Cr: For Pb, 83% of the lakes have decreasing trends and 6% have increasing trends; for Cr, 54% of the lakes have decreasing trends and none have increasing trends. Mass accumulation rates of metals in cores, adjusted for background concentrations, decrease from the 1970s to the 1990s, with median changes ranging from -46% (Pb) to -3% (Hg and Zn). The largest decreases are from lakes in dense urban watersheds where the overall metals contamination in recently deposited sediments has decreased to one-half its 1970s median value. However, anthropogenic mass accumulation rates in dense urban lakes remain elevated over those in lakes in undeveloped watersheds, in some cases by as much as two orders of magnitude (Cr, Cu, and Zn), indicating that urban fluvial source signals can overwhelm those from regional atmospheric sources. ?? 2006 SETAC.

  1. 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.

  2. Reconstruction of historical atmospheric Pb using Dutch urban lake sediments: a Pb isotope study.

    PubMed

    Walraven, N; van Os, B J H; Klaver, G Th; Middelburg, J J; Davies, G R

    2014-06-15

    Lake sediments provide a record of atmospheric Pb deposition and changes in Pb isotope composition. To our knowledge, such an approach has not previously been performed in The Netherlands or linked to national air monitoring data. Results are presented for Pb content and isotope composition of (137)Cs dated lake sediments from 2 Dutch urban lakes. Between 1942 and 2002A.D. anthropogenic atmospheric Pb deposition rates in the two lakes varied from 12±2 to 69±16μgcm(-2)year(-1). The rise and fall of leaded gasoline is clearly reflected in the reconstructed atmospheric Pb deposition rates. After the ban on leaded gasoline, late 1970s/early 1980s, atmospheric Pb deposition rates decreased rapidly in the two urban lakes and the relative contributions of other anthropogenic Pb sources - incinerator ash (industrial Pb) and coal/galena - increased sharply. Atmospheric Pb deposition rates inferred from the lake record a clear relationship with nearby measured annual mean air Pb concentrations. Based on this relationship it was estimated that air Pb concentrations between 1942 and 2002A.D. varied between 5 and 293ng/m(3). PMID:24705301

  3. Anthropogenic sources of arsenic and copper to sediments in a Suburban Lake, Northern Virginia

    USGS Publications Warehouse

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

  4. Evaluation of Oxygen, Carbon, and Nitrogen Isotopic Paleoenvironmental Proxies in Lake Erie Sediments

    NASA Astrophysics Data System (ADS)

    Meyers, P. A.; Knowlton, C.; Eadie, B. J.; Robbins, J. A.; Lansing, M.

    2004-05-01

    The oxygen isotopic composition of calcium carbonate that precipitates in hardwater lakes is affected by meteorologic factors whereas the inorganic and organic carbon and nitrogen isotopic compositions of lake sediments are influenced by biological productivity within the lake. All of these isotopic proxies are potentially subject to post-depositional diagenesis. We have measured the isotopic compositions at 1-cm intervals in four sediment cores that were collected in 1988, 1991, and 2003 from eastern Lake Erie to evaluate the effects of diagenesis on records of paleoenvironmental change. We have compared the isotopic contents and the mass accumulation rates of the aquatic productivity proxies organic carbon and calcium carbonate of the different cores to each other and to meteorological records beginning in 1895. Eutrophication accelerated calcite dissolution, but isotopic proxies are preserved. Calcite del 18O values that become smaller from 1980 to 1998 in the absence of evidence of a summer temperature change suggest a change in air mass trajectories. In contrast, a shift to larger del 18O values from 1905 to 1910 that is accompanied by diminished calcite precipitation and higher lake levels suggests a period of cooler summer temperatures. Increases in inorganic and organic del 13C values, del 15N values, and organic carbon accumulation starting in 1960 reflect the heightened productivity caused by anthropogenic nutrient increases to Lake Erie.

  5. Evidence for mild sediment Pb contamination affecting leaf-litter decomposition in a lake.

    PubMed

    Oguma, Andrew Y; Klerks, Paul L

    2015-08-01

    Much work has focused on the effects of metal-contaminated sediment on benthic community structure, but effects on ecosystem functions have received far less attention. Decomposition has been widely used as an integrating metric of ecosystem function in lotic systems, but not for lentic ones. We assessed the relationship between low-level sediment lead (Pb) contamination and leaf-litter decomposition in a lentic system. We measured 30-day weight loss in 30 litter-bags that were deployed along a Pb-contamination gradient in a cypress-forested lake. At each deployment site we also quantified macrobenthos abundance, dissolved oxygen, water depth, sediment organic content, sediment silt/clay content, and both total sediment and porewater concentrations of Cd, Cu, Ni, Pb and Zn. Principal components (PC) analysis revealed a negative relationship between Pb concentration and benthic macroinvertebrate abundance, and this covariation dominated the first PC axis (PC1). Subsequent correlation analyses revealed a negative relationship between PC1 and percent leaf-litter loss. Our results indicate that leaf-litter decomposition was related to sediment Pb and benthic macroinvertebrate abundance. They also showed that ecosystem function may be affected even where sediment Pb concentrations are mostly below threshold-effects sediment quality guidelines--a finding with potential implications for sediment risk assessment. Additionally, the litter-bag technique used in this study showed promise as a tool in risk assessments of metal-contaminated sediments in lentic systems. PMID:26115904

  6. 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. PMID:23911339

  7. 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.

  8. 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). PMID:25026595

  9. 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.

  10. Remnants of marine bacterial communities can be retrieved from deep sediments in lakes of marine origin.

    PubMed

    Langenheder, Silke; Comte, Jérôme; Zha, Yinghua; Samad, Md Sainur; Sinclair, Lucas; Eiler, Alexander; Lindström, Eva S

    2016-08-01

    Some bacteria can be preserved over time in deep sediments where they persist either in dormant or slow-growing vegetative stages. Here, we hypothesized that such cells can be revived when exposed to environmental conditions similar to those before they were buried in the sediments. To test this hypothesis, we collected bacteria from sediment samples of different ages (140-8500 calibrated years before present, cal BP) from three lakes that differed in the timing of their physical isolation from the Baltic Sea following postglacial uplift. After these bacterial communities were grown in sterile water from the Baltic Sea, we determined the proportion of 16S rRNA sequence reads associated with marine habitats by extracting the environment descriptive terms of homologous sequences retrieved from public databases. We found that the proportion of reads associated with marine descriptive term was significantly higher in cultures inoculated with sediment layers formed under Baltic conditions and where salinities were expected to be similar to current levels. Moreover, a similar pattern was found in the original sediment layers. Our study, therefore, suggests that remnants of marine bacterial communities can be preserved in sediments over thousands of years and can be revived from deep sediments in lakes of marine origin. PMID:26929161

  11. 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...

  12. 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

  13. 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

  14. Integrated sediment quality assessment through biomarker responses and bioavailability measurements: Application in Tai Lake, China.

    PubMed

    Qi, Hong-Xue; Li, Hui-Zhen; Ma, Ping; You, Jing

    2015-09-01

    A weight of evidence (WoE) framework has been applied to assess sediment quality of a typical freshwater lake, Tai Lake in China, where the sediments were contaminated by various chemicals but showed no acute lethality to the benthic invertebrate, Chironomus dilutus. A quantitative scoring method was employed to integrate three lines of evidence (LoE), including adverse effects in life cycle bioassays, biomarker responses, and bioavailability-based chemical analysis. Six biomarkers were determined in C. dilutus after the exposure to the sediments from Tai Lake and provided sensitive indication of sublethal effects at the molecular level. The biomarkers included cytochrome P450, glutathione S-transferase, carboxylesterase, acetylcholinesterase, catalase, and lipid peroxidation. The changes of the biomarkers were summarized for individual sampling sites by computing the integrated biomarker response (IBR) indices. Complementary information was also confirmed by the interrelationship of the LoEs. The IBR indices gained before pupation correlated well with the impairments of emergence of the midges, and altered acetylcholinesterase was corroborated by the detection of chlorpyrifos, an organophosphate pesticide. The relationship between bioavailable toxic units estimated by Tenax extractable concentrations of chemicals in sediment and the observed toxicity in the midges helped to identify the putative toxicity contributors to C. dilutus. Overall, the WoE method clearly distinguished the contaminated sites and ranked them by the level of contamination.