Heavy metals pollution on the sediments in lakes Dianchi, Erhai and Poyanghu and historical records

In this paper²¹⁰ Pb and ¹³⁷Cs dating methods were used to determine sedimentation rates of lakes Dianchi, Erhai and Poyanghu, and to establish the time scale of the sediments. Also based on geochemical records in the sediment column, the historical variation in heavy metal content over the past one hundred years was determined. Some element concentration increased rapidly after the 1970s, such as Cu, Zn and Mn in the sediments of northern Lake Dianchi, Cd and Mn in southern Lake Erhai and in the west central parts of Lake Poyanghu, Our investigations indicate that the increase in element concentration is caused by human activities. In order to understand the extent of the effect caused by human activities, we have calculated the flux of Zn, Cd and Mn. Results show that the flux caused by human activities is seven times greater than the natural one and the ratio is about 2 times in Lake Erhai and Lake Poyanghu.     

137Cs in sediments of deep lakes

Sedimentation rate of suspensions (0.3–18.2 mm/yr) was determined on the basis of layer-by-layer distribution of ¹³⁷Cs (global and Chernobyl) in the cores of bottom sediments (BS) from 16 lakes located in the high and moderate latitudes of the Northern Hemisphere. Profiles of ¹³⁷Cs concentration in the BS cores were analyzed. Sedimentation rates in the limnic zones of deep-water lakes were calculated using ¹³⁷Cs accumulated in the finely-dispersed component of mineral suspension.     

Sedimentologic and palynologic records of the last deglaciation and Holocene from Ballston Lake, New York

Continuous pollen and sediment records from two ∼8.5-m-long cores document late Pleistocene and Holocene sedimentation and vegetation change in the Ballston Lake basin, eastern New York State. Pebbles at the base of both cores and the geomorphology of the watershed reflect the presence of the Mohawk River in the basin prior to ∼12,900 ± 70 cal yr B.P. Ballston Lake formed at the onset of the Younger Dryas (YD) by an avulsion of the Mohawk River. The transition from clay to gyttja with low magnetic susceptibility (MS), low bulk density, and high organic carbon indicates rapid warming and increased lake productivity beginning 11,020 cal yr B.P. MS measurements reveal that the influx of magnetic particles, associated with pre-Holocene clastic sedimentation, ceased after ∼10,780 cal yr B.P. The pollen record is subdivided into six zones: BL1 (12,920 to 11,020 cal yr B.P.) is dominated by boreal forest pollen; BL2 (11,020 to 10,780 cal yr B.P.) by pine (Pinus) forest pollen; BL3 (10,780 to 5290 cal yr B.P.) by hemlock (Tsuga) and mixed hardwood pollen; BL4 (5290 to 2680 cal yr B.P.) by mixed hardwood pollen; BL5a (2680 cal yr B.P. to 1030 cal yr B.P.) by conifer and mixed hardwood pollen; and BL5b (1030 cal B.P. to present) by increasing ragweed (Ambrosia) pollen. A 62% decrease in spruce (Picea) pollen in <320 cal years during BL1 reflects rapid warming at the end of the YD. Holocene pollen zones record more subtle climatic shifts than occurred at the end of the YD. One of the largest changes in the Holocene pollen spectra began ∼5300 cal yr B.P., and is characterized by a marked decline in hemlock pollen. This has been noted in other pollen records from the region and may record preferential selection of hemlock by a pathogen or parasites.     

Cluster analysis of marine sediments and waste deposits in New York bight

Cluster analysis of some chemical characteristics of marine sediments and associated waste deposits in the New York Bight reveals the existence of four cluster facies. Cluster facies I is the sediment containing dredged wastes from New York Harbor. Cluster facies II is the widespread sand and gravel deposit of the continental shelf. Cluster facies III is the finergrained material in the Hudson Channel and the material accumulated in the sewage sludge disposal area. Cluster facies IV is not easily identified; it may correspond to some relict sedimentary feature in the area. Editor's Note: Ali is now with the Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543; Gross is now with Chesapeake Bay Institute. The Johns Hopkins University, Baltimore, Maryland 21218.     

Sequestration mechanisms and anthropogenic inputs of rhenium in sediments from Eastern Canada lakes

The concentrations of Re, as well as those of several other geochemical variables, were measured in dated sediment cores and in porewater samples from four lacustrine basins in Eastern Canada: one, perennially oxic, located 40 km from Québec City and three, seasonally anoxic, located within 25 km of non-ferrous metal smelters. The drainage basins of these lakes are uninhabited and have not been affected by human activity or wildfires. All of the depth profiles of dissolved Re indicate: higher Re concentrations in the water overlying the sediment than in the porewater; diffusion of Re across the sediment-water interface; a progressive decrease in porewater Re concentrations to reach minimum values of ∼0.5 pM within a 10-cm sediment depth interval. Modeling of these Re porewater profiles with a one-dimensional transport-reaction equation indicates that Re is removed from porewater within this depth interval. Based on thermodynamic predictions of Re speciation and of saturation states and on comparison of these predictions with sulfide porewater profiles, we infer that Re is removed from porewater by precipitation of rheniite (ReS_2(s)). The rate constant for the formation of ReS_2(s) in sediments is estimated from the modeling exercise to be 0.51 ± 0.64 × 10⁻²¹ mol cm⁻³ s⁻¹. Accumulation of sedimentary Re shows a strong authigenic component, as in anoxic marine sediments. Sharp increases in solid-phase Re during the last century are attributed to atmospheric deposition of anthropogenic Re deriving from coal burning and nearby smelter emissions.     

Biogenic and abiogenic polynuclear aromatic hydrocarbons in sediments from two remote Adirondack lakes

Sediment cores from Sagamore Lake and Woods Lake in New York State's Adirondack Park, an area remote from industrial activities, were analyzed for polynuclear aromatic hydrocarbons (PAH) by high resolution gas chromatography/mass spectrometry (GC/MS). Their composition and distribution with depth in the sediment indicate that the parental PAH in the surface sediments are primarily produced by anthropogenic combustion of fossil fuels. Perylene in deep sediments is apparently transformed from natural precursors in the reducing environment, however, the exact precursors remain unknown. The rather even sediment distributions of the non-parental PAH differ from the parental, suggesting biogenic origins. Based on their chemical structures, retene and alkylated and partially hydrogenated phenanthrenes are believed to be biogenically converted from abietic acid; hydrochrysenes and hydropicenes, from pentacyclic triterpenes.     

Distribution of nitrogen forms in surface sediments of lakes from different regions,China

The characteristics of nitrogen fractions in the surface sediments of lakes from Eastern Plain Region, Yunnan-Guizhou Plateau Region, Northeast China Region, Qinghai-Tibet Plateau Region and Mongolia-Xinjiang Plateau Region were investigated and the differences of five lake regions on nitrogen fractionation were discussed. The results indicated that organic nitrogen (N_org) was the major nitrogen fraction accounting for 76.38–92.02 % of N_tot in sediments. The rank order of average N_org and N_tot of sediments in five lake regions was: Yunnan-Guizhou Plateau Region > Northeast China Region > Mongolia-Xinjiang Plateau Region > Qinghai-Tibet Plateau Region > Eastern Plain Region. The exchangeable nitrogen had a similar distribution as organic nitrogen in the studied sediments. NH₄ ⁺–N is the main exchangeable nitrogen of sediments in the studied lakes except in Lake Qinghai and Lake Yamdrok which contained higher nitrate concentrations than ammonium. Fixed ammonium (N_fix) in the sediments of studied lakes was irregularly distributed with the values ranging from 99.45 to 329.02 mg/kg. TOC was significantly and positively correlated with ammonium, nitrate, N_org and N_tot, while N_fix was negatively correlated with nitrate probably due to electrostatic attraction between N_fix and nitrate in layers of sediments.     

西藏错鄂湖和羊卓雍湖水体及沉积物中有机氯农药的初步研究

对2002年5月采集的西藏错鄂湖和羊卓雍湖的水和沉积物样品进行了实验及分析。结果表明，这2个高原湖泊均不同程度地受到有机氯农药的污染，并具有多种有机氯农药的同时存在、在沉积柱上近表层没有含量下降趋势以及南部的羊卓雍湖污染程度高于藏北的错鄂湖等特点，反映出湖泊中的有机氯农药有可能是随孟加拉湾洋暖流由南向北带人的。两个湖泊的水与沉积物中滴滴涕(DDTs)和六六六(HCHs)含量甚至与我国东部地区的一些淡水水体相近，这种现象很可能表明，大气沉降的有机氯农药可在青藏高原湖泊水体与沉积物中发生一定程度的累积。长远地看，这一过程将可能对青藏高原野生动物产生负面影响。     

Interpretation of seismic and potential field data from western New York State and Lake Ontario

Lithoprobe and industry seismic profiles have furnished evidence of major zones of easterly dipping Grenville deformed crust extending southwest from exposed Grenville rocks north of Lake Ontario. Additional constraints on subsurface structure limited to the postulated Clarendon–Linden fault system south of Lake Ontario are provided by five east–west reflection lines recorded in 1976. Spatial correlations between seismic structure and magnetic anomalies are described from both Lake Ontario and the newly reprocessed New York lines.In the Paleozoic to Precambrian upper crust, the New York seismic sections show: (1) An easterly thickening wedge of subhorizontal Paleozoic strata unconformably overlying a Precambrian basement whose surface has an apparent regional easterly dip of 1–2°. Minor apparent normal offsets, possibly on the order of tens of meters, occur within the Paleozoic section. The generally poorly reflective unconformity may be locally characterized by topographic relief on the order of 100 m; (2) Apparent local displacement on the order of 90 m at the level of the Black River Group diminishes upward to little or no apparent offset of Queenston Shale; (3) Within the limited seismic sections, there appears to be no evidence that the complete upper crustal section is vertically or subvertically offset; (4) Dipping structure in the Paleozoic strata (15° to 35°) resembles some underlying Precambrian basement elements; (5) The surface continuity of inferred faults constituting the Clarendon–Linden system is not strongly supported by the seismic data.Beneath the Paleozoic strata, the seismic sections show both linear and arcuate reflector geometry with easterly apparent dips of 15° to 35° similar to the deep structures imaged on seismic lines from nearby Lake Ontario and on Lithoprobe lines to the north. The similarity supports an extension of easterly dipping Central Metasedimentary Belt structures of the Grenville orogen from southern Ontario to beneath western New York State.From a comparison of the magnetic and gravity fields with the New York seismic sections, we suggest: (1) The largely nonmagnetic Paleozoic strata appear to contribute negligibly to magnetic anomalies. Seismically imaged fractures in the New York Paleozoic strata appear to lie mainly west of a positive gravity anomaly. The relationship between magnetic and gravity anomalies and the changes in the geometry of interpreted Precambrian structures remains enigmatic; (2) North to northeast trending curvilinear magnetic and gravity anomalies parallel, but are not restricted to the principal trend of the postulated Clarendon–Linden fault system. Paleozoic fractures of the Clarendon–Linden system may partly overlie a southward extension of the Composite Arc Belt boundary zone.     

Holocene storminess inferred from sediments of two lakes on Adak Island,Alaska

The abundance of sedimentary organic material from two lakes was used to infer past Holocene storminess on Adak Island where frequent storms generate abundant rainfall and extensive cloud cover. Andrew and Heart Lakes are located 10 km apart; their contrasting physical characteristics cause the sedimentary organic matter to respond differently to storms. Their records were synchronized using correlated tephra beds. Sedimentation rates increased between 4.0 and 3.5 ka in both lakes. Over the instrumental period, Andrew Lake biogenic-silica content (BSi) is most strongly correlated with winter sunlight availability, which influences photosynthetic production, and river input, which influences the dilution of BSi by mineral matter. Heart Lake BSi is likely affected by wind-driven remobilization of sediment, as suggested by correlations among BSi, the North Pacific Index, and winter storminess. The results indicate relatively stormy conditions from 9.6 to 4.0 ka, followed by drying between 4.0 and 2.7 ka, with the driest conditions from 2.7 to 1.5 ka. The stormiest period was between AD 500 and 1200, then drying from 1150 to 1500 and more variable until 1850. This record of Holocene storminess fills a major gap at the center of action for North Pacific wintertime climate.     

Mineralogy and geochemistry of sediments in arid lakes of Australia

Arid lakes of South, Central and Western Australia generally fill local depressions in Pre-Cambrian rocks. Their hydrochemical evolution represents a special type within the system of inland waters and is characterized by the lack of carbonate sedimentation. The mineralogical and chemical composition of the fine-grained lake deposits is mainly influenced by mechanical weathering products, indicating a distinct detrital heritage from the lithology of the lake basins and of the surrounding areas.Thus, sediments from arid lakes provide simplified conditions to evaluate both (1) economic metal accumulations and (2) baseline data for environmental geochemistry. The former is shown by the concentrations of nickel, chromium and cobalt in lakes of the Western Australian greenstone area. The latter is demonstrated by the concendations of zinc and copper, which are particularly uniform and similar to average shale composition; elevated contents of lead in sediments in some of the lakes studied might indicate an increase of atmospheric lead pollution.

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Zusammenfassung Die Trockenseen Süd-, Zentral- und Westaustraliens füllen lokale Vertiefungen, überwiegend in präkambrischen Gesteinen, mit meist geringmächtigen Ablagerungen. Ihre hydrochemische Entwicklung stellt einen besonderen Typus im System der Binnengewässer dar und zeichnet sich durch das Fehlen von Karbonatabscheidungen aus. Die mineralogische und chemische Zusammensetzung der feinkörnigen Seeablagerungen ist in erster Linie von mechanischen Verwitterungseinflüssen geprägt und läßt eine deutliche detritische Verwandtschaft zu den Gesteinen im Seebecken und der näheren Umgebung erkennen.Die Ablagerungen in ariden Seen bieten deshalb günstige Voraussetzungen (1) zur Exploration nutzbarer Metallanreicherungen und (2) zur Ermittlung von background Daten für umwelt-geochemische Untersuchungen. Der erstgenannte Aspekt wird anhand von Nickel-, Chrom- und Kobaltanreicherungen in See-Sedimenten Westaustraliens beschrieben. Für den zweiten Anwendungsbereich sind vor allem die Zink- und Kupferwerte zu nennen, die sehr geringe Schwankungen aufweisen und mit ihren Durchschnittsgehalten den mittleren Tongesteinsanteilen dieser Elemente entsprechen; die Zunahme der Bleigehalte in den Sedimenten einiger der untersuchten australischen Trockenseen könnte einen Hinweis auf den Anstieg der atmosphärischen Bleiverschmutzung darstellen.

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Résumé Les lacs arides de l'Australie du Sud, de l'Ouest et du Centre représentent un type spécial dans la système des eaux continentales. Leur développement hydrochimique se caractérise par l'absence d'une précipitation de carbonates. La composition minéralogique des sédiments lacustres est surtout influencée par une dégradation nonchimique et montre un »héritage détritique« distinct des formations rocheuses situées dans le basin lacustre et dans sa proximité.Les sédiments dans les lacs arides offrent donc des conditions favorables (1) à l'exploration des enrichissements de métaux exploitables et (2) à l'évaluation de données fondamentales (»background«) pour les analyses géochimiques de l'environnement. Le premier de ces deux aspects sera décrit au moyen des enrichissements de nickel, de chrome et de cobalt dans les sédiments lacustres de l'Australie de l'Ouest. Pour le second aspect et pour son application, il faut avant tout signaler les teneurs de zinc et de cuivre, qui varient très peu et qui correspondent aux teneurs moyennes de ces métaux dans les roches argileuses; l'enrichissement en plomb dans les sédiments de quelques lacs arides explorés en Australie pourrait donner une indication sur l'accroisement de la pollution atmosphérique par le plomb.

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Assessment of branched GDGTs as temperature proxies in sedimentary records from several small lakes in southwestern Greenland

This study of five small (<3.0 ha) lakes in southwestern Greenland examines the veracity of branched glycerol dialkyl glycerol tetraethers (br GDGTs) as a temperature proxy in lacustrine systems. The proximity (<5 km) of the lakes suggests that their temperature history, and thus their br GDGT records, should be similar. Distributions of br GDGTs in (i) surface sediments from all five lakes, (ii) ¹⁴C-dated sediment cores from two lakes (Upper and Lower EVV Lakes) and (iii) soil samples from the area surrounding the lakes were examined. The temporal records of br GDGT-based temperature for the two cores exhibited both similarities and major discrepancies. The differences between the paleotemperature records for the two lakes suggest that br GDGTs are not solely soil-derived, reflecting air temperature, but also indicate an additional br GDGT contribution from another source. Among the broader suite of lake sediments, there was a strong correlation (R² 0.987) between br GDGT-based surface sediment temperatures and measured summer bottom water temperatures for the four lakes with hypoxic/anoxic bottom waters, including Upper EVV Lake. The correlation suggests production of br GDGTs by anaerobic bacteria within the bottom water and/or sediment–water interface, reflecting environmental temperature for the individual lakes and augmenting the uniform, soil-derived signal. Hence, assessment of br GDGTs in Greenland lake sediments provides evidence for their origin from anaerobic autochthonous bacteria and indicates that interpretation of lacustrine br GDGT-based paleotemperature records requires contextual knowledge of individual lake systems and potential source(s) of sedimentary br GDGTs.     

Recent paleolimnology of three lakes in Northwestern Minnesota

A paleolimnological study was undertaken to investigate changes in three Minnesota lakes over the last 100 years and to demonstrate the stratigraphic effects of cultural eutrophication in two of them. The study combined the analysis of the lake sediment from short cores with stratigraphic analyses of pollen, plant macrofossils, mollusks, diatoms and certain other algae, chydorid Cladocera, and Daphnia ephippia.The rise of Ambrosia type pollen (ragweed) marks the onset of interference with the landscape by European man, which can be closely dated. Calculations of sedimentation rates from this base gave reasonable correlations of other stratigraphic events with historical events.Elk Lake is considered “unpolluted” today and was chosen as a control. Man's effects are limited to logging some of the surrounding forest and to the construction of a dam. Small changes in the lake's fauna and flora are demonstrated, showing the sensitivity of the lake to changes in its catchment area.Lake Sallie and St. Clair Lake, in the same watershed as the city of Detroit Lakes, have been affected not only by logging but also by addition of nutrients from agricultural runoff and sewage effluent. Considerable responses by the lake organisms are apparent. In Lake Sallie the changes were gradual, but in St. Clair Lake they were very abrupt because the lake was partially drained at the same time and the water volume was thereby reduced.The merits of such an integrated study, the types of information gained from the analyses of the various fossils, and the wider application of the results are discussed.     

Distribution of Pb between sediments and pore water in Woods Lake,Adirondack State Park,New York,U.S.A.

Interstitial water samples and sediments were collected from acidified Woods Lake (pH= 5.0) to evaluate Pb profile stability and distribution between the solid and aqueous phases. A simple equation was developed to describe the distribution coefficient for Pb(Kd_Pb), based on the sample moisture content and analyte concentrations in bulk sediment and pore water. In Woods Lake sediment Kd_Pb values ranged from 6.7 × 10⁴to6.7 × 10⁵ml/g. The affinity of Pb for the solid phase was further demonstrated by inverting a sediment core and leaving it for 10 months in situ. Upon retrieval, the Pb profile was found to have remained intact over the same depth, albeit inverted, as in the surrounding sediment. Geochemical modeling using MINTEQA2 demonstrates that Pb solids that may reasonably be expected to precipitate were all undersaturated by several orders of magnitude with respect to the interstitial water, indicating that Pb was sorbed to, rather than precipitated in, Woods Lake sediment.     

西藏盐湖沉积物：一种潜在的铷、铯资源

铷、铯是我国战略性关键矿产资源。西藏盐湖卤水中赋存着丰富的铷、铯资源,但是品位普遍低于10 mg/L。根据热泉与盐湖锂、铷、铯等元素的补给关系和含量差异特征及铷、铯极易被黏土矿物吸附等特点,推测盐湖沉积物中赋存一定规模的铷、铯资源。为验证该推测,本文选取西藏拉果错、聂尔错、依布茶卡、当穹错、扎布耶茶卡等5个典型盐湖,采集卤水和沉积物样品各5件,开展水体中铷、铯含量和沉积物矿物成分分析,结合沉积物分相淋滤实验,得出如下结论：西藏拉果错、当穹错、聂尔错盐湖卤水铷、铯含量和资源量与其补给量差异显著,大量的铷、铯资源消耗于盐湖沉积物中;盐湖沉积物中的铷、铯含量远高于卤水。铷、铯在沉积物水溶相、碳酸盐相中含量较低,主要以吸附形式赋存于黏土矿物(主要为伊利石),吸附点位包括基面位置、难解吸的磨损边缘及层间位置。盐湖沉积物铷、铯资源量远超大型矿床规模,黏土矿物中铷、铯含量高达100 n×10-6,超过固体盐类矿产综合评价指标,相较于现有盐湖钾产品中的铷资源、含铯硅华中的铯资源开发,具有较好的开发利用性,是一种潜在的铷、铯资源。本研究成果有助于完善盐湖铷、铯富集成矿机制,并为高效开发盐湖中的铷、铯资源提供理论支撑。     

Radiocarbon deficiencies of US Gulf Coast lakes compromise paleo-hurricane records

Radiocarbon assays of sediments from Lake Shelby, US Gulf Coast, exhibit substantial ¹⁴C deficiencies of 9.3% and 4.7% for the limnic sapropel and associated fresh-water clams Rangia cuneata, respectively. Measured radiocarbon dates from the sapropel and clams require corrections of 785 ± 80 and 365 ± 90 ¹⁴C yr (1σ), respectively, in order to achieve consistency with the radiocarbon time scale. Lake sediments of the US Gulf Coast serve as unique repositories of pre-historic hurricane strikes. Previously unrecognized radiocarbon deficiencies likely render compromised chronologies of the paleo-hurricane records, and erroneous estimates of return period and landfall probability that are derived from the storm chronologies. The recalculated severe hurricane chronologies suggest that the annual landfall probabilities of the last millennium on the US Gulf Coast are equal to, or higher than, the preceding three millennia.     

Holocene records of eolian dust deposition from high-elevation lakes in the Uinta Mountains,Utah, USA

Radiocarbon-dated sediment cores from subalpine lakes were used to investigate post-glacial dust deposition in the Uinta Mountains (Utah, USA). Lake sediments were geochemically characterized with ICP-OES, ICP-MS and XRF core scanning. Collections from passive samplers constrain the properties of modern dust, and samples of regolith constrain properties of the local material within the watershed. Ca and Eu are more abundant in dust, whereas Ti and Zr are more abundant in local regolith. As a result, the Ca/Ti and Eu/Zr ratios are indices for the dust content of lake sediment. In all records, the dust index rises in the early Holocene as watersheds became stabilized with vegetation, reducing the influx of local material. After this point, values remained above average through the middle Holocene, consistent with an increased dust content in the sediment. Dust index values drop in the late Holocene in most lakes, suggesting a decrease in dust abundance. Generally synchronous shifts in dust index values in cores from lakes in different parts of this mountain range are evidence of enhanced dust deposition in this region during the middle Holocene, and are consistent with a variety of records for increased aridity in the south-western USA at this time.