Aliphatic and polyaromatic hydrocarbons in bottom sediments of offshore mouth area of the Volga

Data on the concentration and composition of aliphatic and polyaromatic hydrocarbons in the surface layer and the body of bottom sediments in Volga delta and on the northern Caspian shelf are given. Volga delta sediments are shown to contain large concentrations of organic compounds. It is established that the concentrations of organic compounds is largely dependent on the dispersiveness of sediments. Anthropogenic hydrocarbons, both oil and pyrogenic, fail to pass the marginal filter of the Volga River and do not reach the open part of the sea. Therefore, the hydrocarbons contained in the bottom sediments on the Caspian Sea shelf are mostly of natural genesis. The distribution of organic compounds in the bottom sediment strata has a complex character. In some cases, their concentration increases because of the higher flux of hydrocarbons (especially, polyarenes in the 1950s).     

Impact of the chemical composition of bottom sediments on internal phosphorus load

Examples of the impact of the content of organic matter and compounds of Al and Fe in freshwater sediments on the phosphorus release from the bottom are studied. The relationships between the phosphorus release from bottom sediments and organic matter concentration in sediments of 22 lakes of the world are obtained and discussed as a result of generalization of actual data.     

Physicochemical state and assessment of technogenic geochemical anomalies in bottom sediments of the Kyibyshev Reservoir near Ulyanovsk City

The results of studying physicochemical properties of bottom sediments in the Kuibyshev Reservoir are given. The evaluated characteristics include their porosity, specific surface area and density, and chemical state characteristics (pH, oil products, organic matter, phenols, and the mobile and total forms of heavy metals). Technogenic geochemical anomalies of bottom sediments are evaluated. The obtained results characterize the environmental state of bottom sediments in the study area.     

Study of Heavy Metal Compound Transformations in Surface Waters

Results of studying Fe(III) hydrolysis and sorption of heavy metal compounds by organic matter of bottom sediments are discussed. The rate of Fe(III) hydrolysis is found to be largely determined by the concentration of dissolved organic substances. Values of kinetic parameters are obtained for heavy metal compounds sorption under static and dynamic conditions. Calculating the solubility of Fe, Cu, Cd, Zn, and Pb sulfides allowed the assessment of the amount of metals lost by bottom sediments due to the formation of metal complexes with dissolved organic substances contained in natural waters.     

Polychlorinated biphenyls and hydrocarbons in bottom sediments of Pechora Basin Rivers

The quantitative concentrations of 21 congeners of polychlorinated biphenyls and 16 priority polycyclic aromatic hydrocarbons were studied in bottom sediments of the Usa River, the largest Pechora’s tributary, and its tributaries located in the central part of Timan-Pechora petroleum province. In accordance with the classification of the regional and international standards, the pollution degree of bottom sediments by organic compounds of those classes was evaluated. Pollution profiles were examined and the character of the dominating source of polychlorinated biphenyls and polycyclic aromatic hydrocarbons for bottom sediments in the region under study was identified. Key words: bottom sediments, polychlorinated biphenyls, profiles of polycyclic aromatic hydrocarbons, petrogenic, pyrogenic pollution source.     

Polychlorinated biphenyls and organochlorine pesticides in bottom sediments of the Irkutsk Reservoir

The concentrations of organochlorine pesticides (HCCH, DDT, and HCB) and 34 congeners of polychlorinated biphenyls were studied in bottom sediments of the Irkutsk Reservoir, the first in the Angara Chain of Reservoirs. The degree of pollution of bottom sediments was evaluated in accordance with classifications of regional and international standards. A correlation was found to exist between the distribution of some organic compounds and organic carbon concentration.     

Microelements Speciations in Bottom Sediments of Udomlya and Pes’vo Lakes

Water Resources - Microelements in bottom sediments may enter different compounds; however, of greatest interest are their mobile forms as the most bioavailable. The microelements speciation in the...     

Long-Term Dynamics of the Concentrations of Organochlorine Compounds and Mercury in the Bottom Sediments of the Chernorechenskoe Reservoir

Water Resources - The accumulation of organochlorine compounds (OCs) and mercury in the bottom sediments of the Chernorechenskoe Reservoir since the mid-1960s to 2008 has been studied....     

Vertical distribution of organic compounds in the bottom sediments of two steppe lakes in Southern Siberia

New data on the distribution of organic compounds at different horizons (0–10, 30–40, and 70–80 cm) of bottom sediments of the fresh Fyrkal Lake (Republic of Khakaßsia) and the salt Lake Mormyshanskoe (Altai Territory) have been collected. The compositions of organic compounds in the sediments in the examined lakes has been found to differ considerably, though some parameters in their composition show changes in the same direction. The concentrations of triterpenoids of the groups of lupane, oleanane, and hopane in the sediments decrease with depth. An increase in the share of saturated compounds in the composition of steroids is accompanied by a decrease in the ratio of their isomers (5β/5α). Terrestrial vegetation dominates among organic matter sources, while, in Lake Fyrkal, the contributions of terrestrial plants and macrophytes are similar. The presence of thermally transformed steroids and triterpenoids throughout the vertical profile of sediments in Lake Mormyshanskoe may be an indication to a slight oil pollution of the water body.     

Volatile Organic Compounds in the Mouth Areas of Small Rivers in Tatar Strait during Under-Ice Period

Water Resources - The distribution of volatile organic compounds was studied in water and bottom sediments of estuaries of small tidal rivers. In the under-ice period, water showed high...     

Properties of fine technogenic sediments and their effect on channel process and self-purification of river water

The role of fine sediments of technogenic origin in channel process is analyzed. The specific features of sedimentation of particles with different density and shape and the issues of flocculation and consolidation of sediments in the bottom part of flow are discussed. Experimental data on the adhesion of particles are given and a relationship for its assessment is proposed. The class of sediments for which the adhesion determines the critical erosion velocity is determined. The processes of river water self-purification and precipitation of fine sediments were compared to show that sedimentation processes play an important role in river water self-purification.     

Persistent organic pollutants in subarctic lakes in the extreme North of European Russia

The paper presents data on the concentrations of persistent organic pollutants in bottom sediments of subarctic lakes on Vaygach Isl. and in the Polar Cis-Urals in the Northern European Russia. Dioxin pollution is estimated at the background level, and the recorded levels of hexachlorobenzene fall within the concentration range identified in the bottom sediments of small lakes in the southwestern Arkhangelsk region. The specific character of the congener profile of polychlorinated dibenzo-p-dioxins and dibenzofurans in bottom sediments is demonstrated, suggesting a relationship between the pollution that forms under the effect of atmospheric transport of persistent organic pollutants from low latitudes in the past and present and the application of dioxin-containing organochlorine chemicals in timber industry.     

Methanogenesis and organic matter destruction in bottom sediments of technogenic water bodies

Traits have been revealed in the microbial processes of methane formation and organic matter destruction in bottom sediments of technogenic water bodies, in which at the abundance of C_org compounds, including toxic, dissolved oxygen deficiency, and low redox potential, organic matter decay in sediments is mostly anaerobic with the predominance of methanogenesis and sulfate reduction. Data on major microbial processes are used to calculate the total sludge destruction; it is maximal in the sediments of low-toxicity technogenic water bodies; organic matter destruction in them is mostly due to methanogenesis; it is minimal in high-toxicity water bodies, the share of sulfate reduction in them increases, and that of methanogenesis decreases.     

Peculiarities of Heavy Metals Accumulation in the Bottom Sediments and Higher Aquatic Plants of the Ivan'kovo Reservoir

Concentrations of heavy metals in the bottom sediments of the Ivan'kovo Reservoir bays are analyzed. The role of higher aquatic plants in the processes of heavy metals accumulation and transformation in bottom sediments is studied. Uneven distribution of microelements in the bottom sediments is found to be typical of the bays, which is related to the character of heavy metals input in the bays and to processes occurring inside the bays themselves.     

Environmental Effects of the Bottom Sediments of the Senezh Reservoir

The formation and accumulation of bottom sediments in the Senezh Reservoir are discussed on the basis of field observations. Data on the bottom sediment thickness, the rates of accumulation, and the concentrations of organic substances, metals, petroleum products, and organic pollutants are presented. The bottom sediments of the reservoir are demonstrated to be still no source of secondary pollution.     

Retrospective Assessment of Bottom Deposits in Kondopoga Bay,Lake Onega

Long-term observations of the chemical composition of bottom sediments in Kondopoga Bay, Lake Onega, are considered. The present-day state of bottom sediments is characterized, and regularities of variations in the composition and properties of sediments occurring in the zone of influence of wastewaters from a pulp and paper plant (PPP).     

Accumulation of Polychlorinated Biphenyls in the Sheksninskii Pool of the Rybinsk Reservoir

Specific features of polychlorinated biphenyl (PCB) distributions in bottom sediments, benthos, and fish of the Sheksninskii Pool of the Rybinsk Reservoir are discussed. It is shown that 95% of the total PCB is accumulated in bottom sediments. Mapping of PCB-polluted bottom sediments with allowance for the sediment type and bed relief is proposed. The obtained data along with coefficients of accumulation in the bottom sediments–benthos–fish chain were used to evaluate the maximum concentration of PCB in bottom sediments at which the environmental risk of fish metabolism disturbance will be minimum. It is shown that once the PCB discharge into the water body is completely eliminated, their presence in the system will still be an ecological hazard for 25–30 years.     

Analysis of the Ecotoxicological Conditions of Amur Bay,the Sea of Japan,by Chemical and Toxicological Characteristics

Water Resources - Data on the concentrations of Cd, Cu, Pb, and Zn in bottom sediments of Amur Bay are given. The pollution of bottom sediments is especially heavy near the central part of...     

Long-term variations in the granulometric composition and spatial distribution of bottom sediments in the Northern Caspian Sea

Granulometric analysis was carried out for bottom sediment of the Northern Caspian Sea sampled in 2001. The results of analysis were used to map the spatial distribution of different types of bottom sediments and evaluate their areas. To identify the changes that have taken place in the granulometric composition and spatial distribution of bottom sediments in a transgression period, the obtained materials were compared with data of the previous survey. The main factors of sediments dynamics are shown to be higher continental runoff and sea transgression.     

Hydrocarbon gases (C1–C5) and organic matter in bottom sediments of the Ivankovo Reservoir on the Volga River

The results of studying the composition of hydrocarbon gases (C₁–C₅) and organic matter in bottom sediments of the Ivankovo Reservoir in 1995, 2004, and 2005 are given. The methods used in the study include vapor-phase gas chromatography, instrumental pyrolysis gas chromatography, and mass-spectrometry for determining organic carbon δ ¹³C_org. The gas field of bottom sediments in different regions of the reservoir varies widely in terms of gas saturation and the spectrum of hydrocarbon gases. This suggests the heterogeneous composition of organic matter in the sediments and different conditions of its input and transformation processes. The gases were found to contain saturated hydrocarbons from methane to pentane C₁–C₅, including isomers i-C₄ and i-C₅ and unsaturated compounds C₂–C₄. A correlation was found to exist between methane distribution and the distribution of its more high-molecular homologues, which confirms their genetic relationship in bottom sediments. The obtained results show an increase in the rate of microbiological processes and organic matter transformation for most regions in the Ivankovo Reservoir. The only exceptions are the zones of Moshkovichskii Bay and the sections at Gorodnya and Konakovo, where technogenic organic matter is being accumulated. The high information value of hydrocarbon gases as biogeochemical markers of the sources of organic matter and the rates of its transformation is demonstrated. The isotopic composition of organic-matter carbon in the bottom sediments of the Ivankovo Reservoir δ ¹³C varies from ?26.21 to ?30.86‰.