Chemical composition of surface sediments of the White Sea

Contents of major elements in surface sediments of the White Sea were determined by the X-ray fluorescence method. Application of the statistical analysis (principal component method and cluster analysis) made it possible to divide the sediments into more or less homogeneous seven groups with different chemical and grain size compositions. In general, the groups corresponded to sediment lithotypes based on the classification elaborated at the Shirshov Institute of Oceanology, Russian Academy of Sciences. Contents of Si and Al are controlled by the ratio of sand-silt and pelite fractions, while variations in the content of Mn (and Fe in part) are governed by the redistribution of elements in the course of redox processes of early diagenesis.     

Associations of microalgae in bottom sediments of marginal filters areas (White Sea bays)

The first results of detailed studies on algae in surface sediments of bays of the White Sea are presented. Both the general patterns of associations of water palynomorphs and diatoms and some regional peculiarities of their formation at different stages of the marginal filter have been discovered.     

Noble metals in the bottom sediments of the Chukchi Sea

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.     

南黄海沉积物常量元素组成及物源分析

通过对南黄海295个站位沉积物样品的常量元素含量分析,研究了南黄海沉积物常量元素组成的R-型聚类分析、R-型因子分析及与物质来源的关系。南黄海沉积物常量元素Al2O3、MgO、K2O、Fe2O3分布基本相似;SiO2分布与Al2O3、MgO、K2O、Fe2O3分布相反;中、西部CaO、CaCO3分布与黄河、长江物源有明显关系;Na2O分布与黄河物质供给有关;TiO2分布反映了长江物质的运移方向。现代黄河物质及老黄河物质主要沉积于南黄海的西部、中部和东南部;海区东部物质反映来自朝鲜半岛物质的对南黄海东部的作用。长江物质主要局限于南黄海的西南和南部区域沉积;TiO2和Ti/Al分布反映了长江物质可能对南黄海中部区域也有所影响     

Carbon isotope composition of organic seston and sediments in a Georgia salt marsh estuary

The distribution of δ¹³C values for organic seston and sediment was determined in three sounds in the Spartina marsh estuaries along the Georgia coast, which had high, moderate, and low inputs of freshwater. Organic matter in all three sounds had similar carbon isotope compositions, for the most part within the range of marine values (δ¹³C of ?18%. to ?24%.). It appears that river flow does not introduce significant quantities of particulate C₃ plant material (δ¹³C of ?25%. to ?28%.) to Georgia estuaries. Evaluation of δ¹³C values of estuarine seston and three size fractions of sediment indicated that while Spartina carbon (δ¹³C of ?13%.) can be an important component of organic matter in intertidal sediments (mean δ¹³C of ?14.3%. to ?20.0%.), it is less so in subtidal sediments (mean δ¹³C of ?18.8%. to ?21.2%.), and it is hardly present at all in the seston (mean δ¹³C of ?24.5%.). δ¹³C values of dissolved inorganic carbon (DIC) in several water samples ranged between ?2.5%. and ?5.6%., suggesting that the isotope composition of estuarine DIC is influenced by respiratory CO₂ derived from metabolism of ¹³C-depleted plant carbon. Phytoplankton production utilizing this comparatively light DIC could be a source of relatively negative δ¹³C carbon in the estuary. Additional origins of estuarine organic matter greatly depleted in ¹³C compared to Spartina carbon remain to be identified.     

南黄海沉积物常量元素组成及物源分析

通过对南黄海295个站位沉积物样品的常量元素含量分析,研究了南黄海沉积物常量元素组成的R-型聚类分析、R-型因子分析及与物质来源的关系。南黄海沉积物常量元素Al2O3、MgO、K2O、Fe2O3分布基本相似;SiO2分布与Al2O3、MgO、K2O、Fe2O3分布相反;中、西部CaO、CaCO3分布与黄河、长江物源有明显关系;Na2O分布与黄河物质供给有关;TiO2分布反映了长江物质的运移方向。现代黄河物质及老黄河物质主要沉积于南黄海的西部、中部和东南部;海区东部物质反映来自朝鲜半岛物质的对南黄海东部的作用。长江物质主要局限于南黄海的西南和南部区域沉积;TiO2和Ti/Al分布反映了长江物质可能对南黄海中部区域也有所影响。     

Concentration and composition of hydrocarbons in bottom sediments from the Sakhalin shelf

Aliphatic and polycyclic aromatic hydrocarbons were examined in the surface layer of bottom sediments from the eastern part of the Sakhalin shelf (the materials were sampled in the summer of 2002). The concentrations of hydrocarbons were determined to have changed since the beginning of the development of oil fields (compared with earlier years). According to the distribution of markers in the hydrocarbon compositions, the bottom sediments are dominated by allochthonous (terrigenous) hydrocarbons, which are the most stable compounds. The presence of transformed anthropogenic oil alkanes, which have never been found before, may be indicative of the increasing pollution of the region.     

Comparative study of vertical suspension fluxes from the water column,rates of sedimentation,and absolute masses of the bottom sediments in the White Sea basin of the Arctic Ocean

A new approach using dispersed organic matter of the water column in sedimentation traps in comparison with the surface layer of the bottom sediments is applied for the study of marine sedimentation. This approach provides the opportunity for an in situ (by fluxes of sedimentary matter in the water column) study of modern sedimentation in the surface layers of the bottom sediments and tracing the changes in the environment and climate at a new technological level. This also allows us to choose the reverse task: to reconstruct the fluxes of the matter and chemical elements in ancient seas by the rates (or absolute masses) of sedimentation.     

Occurrence forms of trace metals in recent bottom sediments from the White and Barents Seas

For the first time based on determination of the geochemical occurrence forms of trace metals the main processes that control the accumulation of elements (Al, Mn, Fe, Mo, Cr, Ni, Co, Cu, Pb, Cd, and As) in the recent sediment cores from the White Sea and Barents Sea were quantified. A high-resolution study of the bottom sediment cores allowed us to estimate the short-term variations (periodicity of 10–15 years) in the accumulation of metals to reveal the periods of maximum Fe and Mn contents in the amorphous hydroxides fraction, which serve as effective adsorbents of the trace elements majority, including heavy metals. The Mn/Fe ratio in the amorphous hydroxides phase can be considered as geochemical indicators of early diagenesis.     

Patterns of mercury distribution in bottom sediments along the Severnaya Dvina-White Sea section

This paper analyses the data on the distribution of mercury in the surface layer of bottom sediments (0–5 cm) obtained in course of sampling trips within the mouth region of the Severnaya Dvina River and the White Sea area. A total of 170 analyses for mercury were performed. Such wide-scale determination of the mercury content in the bottom sediments was carried out for the first time in the study region. The patterns of mercury distribution in the Severnaya Dvina River-White Sea transect are revealed and described. It is shown that the marginal filter of the Severnaya Dvina River facilitates cosedimentation of the main portion of anthropogenic mercury with suspended matter. This drastically decreases the risk of penetration of mercury to the White Sea waters and partially (with the gravity current) to the Barents Sea waters. In general, the Severnaya Dvina River is characterized by mercury pollution of a local scale within the urban territories. No regional pollution of the White Sea off the marginal filter was revealed.     

Distribution of hydrocarbons in water and bottom sediments of the Northern and Middle Caspian Sea

A study of two classes of hydrocarbons (HCs)—aliphatic and polycyclic aromatic—in suspended matter of the surface waters and bottom sediments of the Northern and Middle Caspian Sea (R/V Nikifor Shurekov, October 2015) is described. It has been determined that oil pollution transported by river runoff and fluid streams flowing from sedimentary formations in the northeastern part are the main sources of hydrocarbons in the river–sea boundaries of the Volga, Terek, and Sulak rivers.     

Chemical composition of the bottom sediments in the middle reaches of the Amur River

The chemical composition of the bottom sediments of the Amur River has been analyzed using modern analytical techniques. It was found that their composition and distribution patterns are controlled by several sources. The most probable sources for the bottom sediments of the studied area are siliceous magmatic or metasedimentary rocks.     

Heavy metal distribution in the surface layer of bottom sediments of the Kara Sea

This paper addresses the distribution of heavy metals (Co, Ni, Cu, Zn, Cd, Sn, Sb, Pb, and Bi) as well as Si, Al, Fe, and Mn in the surface (0–2 cm) layer of bottom sediments of the Kara Sea. The contents of these elements are determined in each of the previously distinguished facies-genetic types of terrigenous sediments: fluvial, glacial, estuarine, shallow water–marine, “background” marine, and relict sediments. It is shown that these types reflect the modern conditions of accumulation of river discharge material, which forms fans of two greatest Siberian rivers, Ob and Yenisei. The main stages are distinguished in heavy metal accumulation. The first stage is related to the avalanche sedimentation of terrigenous sediments in the estuary and characterized by the elevated contents of Co, Ni, Cu, Zn, Cd, Sb, and Bi. The second stage reflects the mechanical differentiation of sedimentary material by waves and bottom currents in a shallow-water sea part adjacent to the estuarine zone, with accumulation of Pb- and Sn-bearing “heavy” ore minerals. The deepwater background terrigenous–marine sediments accumulate mainly Ni, Zn, and Cd, as well as Mn. The relict sediments differ in the high contents of Si, Mn, and Sn.     

Specific features of the distribution of trace and rare earth elements in recent bottom sediments in the lower course of the Severnaya Dvina River and White Sea

The paper discusses results of the lithogeochemical examination of recent bottom sediments in the lower course of the Severnaya Dvina River and White Sea. It has been established that the average concentration of several trace elements (Hf, Sc, Co, Y, Ni, V, Cr, Zr, Ba, and others) therein correlates with the content of the silt-pelite fraction. Maximal concentrations of the majority of above elements are confined to the silty-clayey sediments at the Basin/Dvina Bay boundary. They localized near the coastal zone only for some clastophile (Zr, Cr, and others). Typical values of the hydrolyzate module, chemical index of alteration, and Al₂O₃/SiO₂ ratio in the aleuropelitic and pelitic sediments of the Severnaya Dvina River delta, Dvina Bay, and the Dvina Bay Basin boundary suggest that these sediments are confined to sufficiently cold climate settings. Data points of sediment composition in discriminant paleotectonic diagrams are scattered over a large field probably due to high contents of the weakly weathered plagioclases, micas, and amphiboles, as well as the hydrogenic process promoting the accumulation of Fe and Mn. The PAAS-normalized spectra of rare earth elements (REE) in bottom sediments of the Pinega and Severnaya Dvina rivers, marginal filter of the latter river, Dvina Bay, and the Dvina Bay Basin boundary are similar to the REE distribution in clayey rocks of the ancient platform cover (except for a slight positive Eu anomaly). The REE systematics and distribution pattern of compositional data points of recent bottom sediments in the Gd_N/Yb_N-Eu/Eu* and Eu/Eu*-Cr/Th diagrams and values of several indicator ratios of trace elements suggest that the studied rocks were formed by the mixing of clastic materials from geochemically contrast provenances: northwestern provenance (Kola-Karelia geoblock), which is mostly composed of the Archean and Early Proterozoic crystalline complexes, and the southeastern provenance (northwestern periphery of the Mezen syncline), which is almost totally composed of Phanerozoic sedimentary rocks. The latter provenance likely played a crucial role in the geochemical signature of recent bottom sediments over a significant area of the White Sea.     

Composition and genesis of the organic matter in the bottom sediments of the East Siberian Sea

The chemical composition of organic matter (C_org, N_org, δ¹³C, δ¹⁵N, and n-alkanes) was studied in the top layer of bottom sediments of the East Siberian Sea. Possible ways were proposed to estimate the amount of the terrigenous component in their organic matter (OM). The fraction of terrigenous OM estimated by the combined use of genetic indicators varied from 15% in the eastern part of the sea, near the Long Strait, to 95% in the estuaries of the Indigirka and Kolyma rivers, averaging 62% over the sea area.