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1.
Regularities of the formation of bottom sediments down to a depth of 1.2 m, as well as factors governing the composition of sediments, waters, and soils in the catchment area of the lake, are discussed. It has been established that the chemical composition of lacustrine sediments is closely associated with the composition of soils in the ambient watersheds, and the soils, in turn, are associated with the composition of the soil-forming rocks. The available data suggest an extremely irregular contamination of the lake system by technogenic radionuclides within the water area. Maximum radiocesium contamination of lacustrine bottom sediments is 350 mCi/km2 (recalculated to year 2000). Concentrations of elements (Cu, Zn, Cr, Ni, Co, Mg, Be, Sb, Mn, and others) in bottom sediments, water, and soils in catchment areas of Lake Kolyvan do not exceed the background values (except for the Hg content in bottom sediments), suggesting that the area under consideration is not contaminated by inorganic technogenic components.  相似文献   

2.
The REE distribution was studied in the bottom sediments of the East Arctic shelf of Russia. It is established that sediments of the Laptev and western East Siberian seas are significantly enriched in REEs, the contents of which are much higher than those of other near-continental basins. The main REE sources are runoff of the Lena River, the basin of which comprises ancient crystalline shields and magmatic rocks enriched in LREEs with significant contribution from the coastal erosion of the ice complex from the Laptev Sea and western East Siberian Sea. The terrigenous flux with a specific REE composition is supplied to the Chukchi Sea through the Bering Strait.  相似文献   

3.
The grain size distribution and fraction composition of bottom sediments (BS) in the Amur River are studied. The total composition of sediments, their clay subfractions—water-peptizable (WPC) and aggregated (AC) clays—and residue after clay elutriation were analyzed. It has been established that contents of Fe, Mn, Zn, and Cu in the clay subfractions are 2–4 times higher than in common bottom sediments and their residue left after the extraction of clay subfractions, confirming a significant role of clay minerals in the accumulation of elements mentioned above. It is shown that diatom algae participate in the accumulation and transport of Fe, Mn, Zn, and Cu in the river water-suspended matter-bottom sediments (clay minerals) system. It has been established that high Zr concentrations in bottom sediments are related to the presence of zircon therein.  相似文献   

4.
Genetic sediment types have been identified based on the study of sediment core PS 1599 of bottom sediments recovered from the eastern continental slope of the Weddell Sea. The XRF analysis of 48 samples from this core carried out at the Vernadsky Institute of Geochemistry and Analytical Chemistry (Moscow) yielded the first comprehensive geochemical characteristics of all genetic types. Methods of correlation and factor analyses were used to outline geochemical associations of sediments and examine causes of their formation, including the role of grain size composition. The results obtained have revealed fundamental differences between sources, mechanisms, and methods of the transportation of sedimentary material for Holocene sediments, on the one hand, and Weichselian sediments, on the other hand.  相似文献   

5.
The paper considers conditions of the accumulation of bottom sediments and the formation of their mineral composition in a specific type of barrier zones that was formed due to the overregulation of natural runoff of the Angara River and construction of the Angara reservoir cascade. It was established that the bottom sediments accumulated in the barrier zone were supplied by the runoff of the Angara River and its tributaries. The mineral composition of solid runoff of the rivers is determined by the petrographic composition of their water drainage basins. Boundaries of the distinguished mineralogical subprovinces of the bottom sediments coincide with a sharp change in the dynamic parameters of water flow. The revealed compositional variations of the heavy fraction depending on the water flow velocity can be used to solve an inverse problem: deciphering the hydrodynamic conditions of the formation of river bed sediments.  相似文献   

6.
Study of the element composition of ten samples of modern terrigenous and carbonate sediments from the northern part of the Caspian Sea by the ICP-MS method showed that these sediments were enriched in sulfur, nonferrous metals, and some related minor elements including Se, Te, Re, and others in comparison with the average composition of sedimentary rocks. It is assumed that local hydrothermal seeps similar to those known on the Cheleken Peninsula and which may be formed in other areas of this tectonically active zone are the sources of these elements. In addition, such a composition of sediments may indicate the sporadic contamination of bottom water with hydrogen sulfide, which has been observed in areas of the South and Middle Caspian by many researchers.  相似文献   

7.
The chemical composition of bottom sediments in the Chukchi and, partly, East Siberian Seas was studied. In the south and west of the Chukchi Sea, a zone has been detected with the accumulation of sediments rich in organic carbon, an increased background content and anomalies of sulfophile metals (Mo, Zn, Hg, Ag, Au), iron-group metals (V, Ni, Co), and some PGE (Ru, Pt). This zone is confined to the neotectonic active system of rift troughs extending from the Bering Strait and eastern Chukchi Peninsula to the continental slope, where it is bounded by the Cenozoic Charlie rift basin of the Canadian hollow. The geochemical features of the carbon-enriched sediments evidence that they formed under oxygen-deficient conditions and, sometimes, in suboxic and anoxic environments near endogenic water and gas sources. The high carbon and metal contents suggest that the very fine-grained sediments in the rift troughs of the Chukchi Sea are a possible analog of some types of ancient highly carbonaceous sediments belonging to black shales.  相似文献   

8.
The distribution of REE in the bottom sediments of Amur Bay accumulated over the last 100 years was studied, and the REE contents were evaluated. The REE contents normalized to North American Shale Composite (NASC) show a negative Ce anomaly and a predominance of LREE and MREE. The inflow and accumulation of REE in the bottom sediments are influenced mainly by natural sources, whereas their dependence on anthropogenic factors is minimal.  相似文献   

9.
The Tazheran lakes are located compactly in the small Tazheran steppe area. Their bottom sediments are predominantly various calcite-dolomite carbonates, and their waters are rich in uranium. The studies have shown that the main process in these lakes is chemogenic carbonate precipitation with the participation of carbon dioxide formed through the bacterial destruction of organic matter. For thermodynamic modeling of the composition of bottom sediments, we chose two lakes with different basic parameters. Calculations were made for the 15-component heterogeneous system H2O-Na-Ca-Mg-K-Sr-Ba-Si-Al-Cl-C-S-Fe-U-Mn including particles in the solution, minerals, and gases at 25 °C and 1 bar. As starting information, we used the obtained analytical data on the natural composition of waters and bottom sediments. The results show that calcite-dolomite carbonates are predominant in the bottom sediments and the destruction of organic matter results in reducing conditions. This confirms the hypothesis of the formation of mineral phases of U(IV) during diagenetic processes in the bottom sediments of the studied lakes.  相似文献   

10.
This paper reports the results of chemical study of bottom sediments of the Zeya and Selemdzha rivers, the largest water streams of the Amur River basin. It was established that the bottom sediments are depleted in practically all analyzed major and trace elements as compared to the upper continental crust (UCC) and Post-Archean Australian Shale (PAAS). It is shown that the bottom sediments of the studied rivers are chemically close to those of the Northeastern China rivers, which is related to the similar geographical and climatic environments. Examination of major-component proportions and trace-element variations suggests that the bottom sediments of the middle reaches of the Zeya River were formed from chemically reworked sources. In contrast, the bottom sediments of the lower reaches of the Zeya and Selemdzha rivers are dominated by physically reworked rather than chemically reworked materials. It is suggested that the bottom sediments of the Zeya River downstream the mouth of the Selemdzha River were formed from material, which was supplied by the Selemdzha River and determined the main geochemical characteristics of the bottom sediments of the lower reaches of the Zeya River. This is presumably related to the fact that the upper reaches of the Selemdzha River is located mainly within the Mongol–Okhotsk fold belt, the complexes of which experienced intense tectonic shearing and brecciation. For this reason, the bottom sediments of the Selemdzha River are mainly dominated by physically reworked rather than by chemically reworked material.  相似文献   

11.
Available data on synthesis, input, and decomposition of organic matter (OM) in the water column and recent bottom sediments of the World Ocean are generalized. The most reliable values of OM production and masses in the ocean, the total supply of organic carbon, and the input of terrigenous OM with coastal erosion, river runoff, and eolian matter are estimated. Maps of fossilization coefficients, distribution, and accumulation of OM in recent bottom sediments of the World Ocean are presented. A numerical expression is proposed for the main circumcontinental pattern of OM accumulation in the ocean. The group and elemental compositions of living matter of the ocean, land, and the Earth as a whole and the organic composition of bottom sediments are briefly considered.  相似文献   

12.
The distribution of heavy metals has been examined in water and bottom sediments of small streams within the Losinyi Ostrov (Elk Island) National Park (Moscow) that are undergoing manmade impacts. We demonstrated that pollution caused by motor vehicles causes seasonal changes in the general composition of the river water and pore solutions in bottom sediments. The strongest pollution of water and sediments was found near the CMHW (Circum-Moscow Highway) (Zn, Pb, Cu). This is expressed in the growth of mobile forms of metals in sediments. We have shown, using Zn as an example, the pollution transformation in the snow-river water-suspension-bottom sediment system.  相似文献   

13.
Sediment samples from the coastal zone of the Gulf of Suez contain a variety of organic compounds from anthropogenic and natural sources. A total of 12 surface samples of bottom sediments were collected with an Ekman grab sampler along an off-shore transect south of Ras Abu el-Darag. The samples were extracted with a mixture of dichloromethane and methanol (3:1 v/v) after drying and sieving through 250 μm mesh. The extracts were derivatized and analyzed by gas chromatography–mass spectrometry in order to characterize the chemical composition and sources of the organic components. Marine with minor terrestrial biota were the major natural sources of organic tracers and included n-alkanoic acids, sterols and saccharides (5.7–76.7%). Anthropogenic sources, from petroleum related activities, detergent usage for spill cleaning and littering, are indicated by the presence of n-alkanes with carbon preference index ≤1.0, hopanes, steranes, unresolved complex mixture of branched and cyclic hydrocarbons, alkyl nitriles, alkamides and plasticizers. Their total relative concentrations ranged from 23.3 to 97.3% of the total extracts. Petroleum residues from natural seepage may also be part of these hydrocarbons. The levels of anthropogenic inputs decrease from about 94% in coastal zone sediments to about 20% in sediments from the reef front.  相似文献   

14.
During Cruise 62nd of the R/V “Professor Gagarinsky” in September, 2014, the carbonate system of sediments and contents of nutrients and organic carbon in pore water were studied in two geochemical stations located in hypoxia areas in the Peter the Great Bay. It was established that the concentrations of silica, phosphorus, and ammonium increase by 5, 10, and 20 times, respectively, with sediment depth to 70–80 cm. The alkalinity, dissolved inorganic carbon, and the partial pressure of carbon dioxide significantly increase with depth, while рН value and organic matter (ОM) decrease. Changes in the chemical composition of pore water with sediment depth (0–80 cm) are caused by anaerobic microbial degradation of OM, concentration of which in the top sediment layer is 2–3%. The degradation products of OM in the bottom waters of bay and pore waters of bottom sediments indicate that its main sources are diatoms. During hypoxia, the oxygen demand rate by sediment surface near Furugelm Island is estimated to be 5 mmol/(m2 day). A combination of such factors as downwelling circulation, the absence of photosynthetically active radiation, and the high oxygen demand rate at the water/sediment interface provides hypoxia formation in the depressions of the Peter the Great Bay bottom topography.  相似文献   

15.
黄河上游河段的形成年代依然存在争论,而银川盆地是黄河上游物质的主要沉积区之一,该盆地沉积序列的研究能为了解黄河上游的物质来源和形成年代提供重要线索。对银川盆地钻孔（PL02）底部进行了碎屑锆石U-Pb测年和碎屑组分统计研究,并与上游黄河沉积物以及盆地周边贺兰山和鄂尔多斯高原西部的锆石U-Pb年龄数据和碎屑组分数据进行了对比分析。结果表明贺兰山和鄂尔多斯高原西部并不是银川盆地晚上新世沉积物的物质供应区,而是黄河将银川盆地以上河段地区物质输送到银川盆地。这一结果进一步证明了黄河上游兰州—银川段在晚上新世已经形成的观点。  相似文献   

16.
Abundance of noble metals (NM) and bulk chemical composition have been studied in bottom sediments of the Chukchi Sea. Distribution of NM and their correlation with major and trace elements in the sediments have been analyzed using multicomponent statistics. It was established that the average contents of NM in the bottom sediments of the Chukchi Sea significantly exceed those both in shelf terrigenous sediments and stratisphere. Osmium and iridium enrich mixed and pelitic sediments relative to shallow-water areas and their influx is presumably determined by erosion of coastal and bottom loose deposits. High Ag, Ru, Au, and Pt contents were identified in the clayey sediments enriched in biogenic elements in the individual areas of the Southern Chukchi plain (Chukchi sea) confined to the intersection zones of submeridional and sublatitudinal structures of the graben-rift system, which was formed in the Mesozoic and activated in the late Cenozoic time.  相似文献   

17.
Results of study of pore waters of bottom sediments from different Baikal basins are presented. The most typical ion distribution patterns reflecting the Baikal sediment diagenesis are given. We have established that in areas with regular sedimentation, in the absence of faults and inflows, the sediment pore waters of three lake basins inherit the chemical composition of the Baikal water, which is stable in time and space. Changes in pore water composition mark general natural anomalies, such as the presence of active faults, tectonic movements, and inflows along permeable zones. In areas with the subsurface occurrence of gas hydrates, thorough long-term research has revealed an anomalous composition of pore waters. It has been established that the anomalies are caused by a discharge of deep-level mud-volcanic fluids. The ejected mud-volcanic waters differ from each other in mineralization, ion composition, and sources, which determines the difference in hydrate formation and the composition of gas hydrates.  相似文献   

18.
This paper discusses the distribution of trace elements in certain genetic horizons of flooded soils and riverside soil cover and compares it with the heavy metal distribution in bottom sediments of the Ivankovo Reservoir area in the Volga River valley. We present data on the chemical and grain-size compositions of bottom sediments and the concentrations of biophile elements and humus in these sediments. Correlation and factor analyses were applied to reveal the relationships between the abundances of heavy metals and humus and the grain-size composition.  相似文献   

19.
Processes governing the formation of rare earth elements (REE) composition are considered for ferromanganese deposits (nodules, separate parts of nodules, and micronodules of different fractions) within the Clarion–Clipperton ore province in the Pacific Ocean. It is shown that ferromanganese oxyhydroxide deposits with different chemical compositions can be produced in sediments under similar sedimentation conditions. In areas with high bioproductivity, the size of micronodules has a positive correlation with the Mn content and Mn/Fe and P/Fe ratios and a negative correlation with Fe, P, REE, and Ce anomaly. The behavior of REE in micronodules from sediments within bioproductive zones is related to increase of the influence of diagenetic processes in sediments as a response to the growth of the size of micronodules. Distinctions in the chemical composition of micronodules and nodules are related to their interrelations with associated sediments. Micronodules grow in sediments using hydrogenous ferromanganese oxyhydroxides. As they grow, micronodules are enriched in the labile fraction of sediments reworked during diagenesis. Sources of the material of ferromanganese nodules are governed by their formation at the water bottom interface. Their upper part is formed by direct settling of iron oxyhydroxides from the bottom water, whereas the lower part is accumulated due to diagenetic processes in sediments. Differences of REE compositions in ferromanganese deposits are caused by the reduction of manganese during diagenesis and its separation from iron. Iron oxyhydroxides form a sorption complex due to the sorption of phosphate-ion from bottom and pore waters. The sorption of phosphate-ion results in an additional sorption of REE.  相似文献   

20.
A long-term complex study of the Angara cascade reservoirs, the largest artificial reservoirs, showed that the bottom deposits were formed at the predominance of terrigenous influx. The compositional-structural and geochemical characteristics of various lithodynamic types of bottom sediments along a generalized transverse profiles testify that they represent a complex system with varying proportions of sandy, silty, and clayey particles and associations of chemical elements. As is indicated by the composition of the abraded rocks, the sedimentation settings, and the type of the lithological-geochemical differentiation of the bottom deposits, the scattering and differentiation of abrasion fluxes occurred simultaneously with the formation of new types of bottom sediments, whose composition was partially inherited from precursor rocks. It was established that the change in the lithodynamic settings in the Angara cascade reservoirs and the trend of the lithological-geochemical differentiation of the bottom sediments are governed by the same laws as in natural basins.  相似文献   

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