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.     

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).     

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.     

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.     

Concentrations of heavy metals in bottom sediments of Lake Dautkul as an indicator of anthropogenic impact in the area south of the Aral Sea

Data on the microelement composition of bottom sediment and water samples from Lake Dautkul for recent years are presented. Concentrations of more than 30 chemical elements are determined using instrumental neutron-activation analysis. This allowed the authors to reveal the regularities in the distribution and accumulation of chemical elements in water and bottom sediments. It is shown that bottom sediments exhibit a cumulative effect and prolonged activity, which adversely affect the aquatic medium and can serve an indicator of anthropogenic impact on the area under consideration.     

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.     

Spatial and temporal transformations of bottom sediments in the Middle Volga reservoirs

Based on the results of long-term observations, spatial and temporal distribution and accumulation of bottom sediments in the Cheboksary and Kuibyshev reservoirs are assessed, and ways of the bottom complex formation are predicted for the near and distant future.     

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.     

Chemical composition of organic and mineral substances in silt bottom sediments of non-contaminated water bodies

Results of studying group and constituent composition of natural organic and mineral substances in silt bottom sediments of non-contaminated freshwater bodies are presented. The chemical composition of the investigated bottom sediments is shown to be complicated, diverse, and include products of autochthonous and allochthonous substance transformation. The necessity of further studying the concentrations of nutrients found in the bottom sediments of non-contaminated freshwater bodies, regarded as the “background” in estimating their environmental state, in studying processes occurring within water bodies, in determining natural and anthropogenic components of mineral and organic substances, as well as in estimating the balneologic value of the water bodies in question is substantiated.     

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.     

Variations in different compounds in Volga water, suspension, and bottom sediments in the summer of 2009

Studies of water, suspension, and sediments of the Volga R. (from Konakovo Town to the delta) showed that at the confluence with tributaries, diffusion and dilution play the major role. Changes in conductivity, Biochemical oxygen demand (BOD₅), pH, suspension, chlorophyll a, dissolved and organic carbon, lipids, and hydrocarbons take place mostly under the effect of natural processes. Typical features in the case of summer low-water period are low chlorophyll a, suspension, and BOD₅. The accumulation of pollutants takes place in bottom sediments because of an increase in the share of C_org, and hydrocarbons have a petroleum and pyrogenic composition.     

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.     

Variability of Trophic State of Bottom Biotopes of the Gorky Reservoir by Sedimentary Pigments

Water Resources - New data on the contents of plant pigments and organic matter in bottom sediments of channel, floodplain and estuarine biotopes of the Gorky Reservoir (upstream Volga, Russia) are...     

Sulfate reduction in natural water bodies. 1. The effect of environmental factors and the measured rates of the process

Sulfate reduction is an important oxidation process involving transformation of organic matter and its components and taking place in the aquatic environment and bottom sediments of water bodies (both fresh and marine) under anaerobic conditions. The intensification of sulfate reduction in water bodies is a sign of a stronger anthropogenic impact on the environment and natural water bodies. The development of sulfate reduction under natural conditions reflects the influence of many environmental factors. The effect of the most important factors (the concentration of organic matter and its components and sulfates, the temperature of aquatic environment, and the abundance and activity of sulfate-reducing bacteria) on the process of sulfate reduction in the aquatic environment and bottom sediments in water bodies is considered.     

Application of electrical and electromagnetic methods to study sedimentary covers in high mountain areas

The results of geophysical studies conducted with selected electrical and electromagnetic methods in the Kondratowa Valley in the Tatra Mountains (the Carpathian Mountains, Poland) are presented in the article. The surveys were performed with the following methods: electrical resistivity tomography (ERT), georadar (GPR) and conductivity meter (CM). The objective of the noninvasive geophysical measurements was to determine the thickness of the Quaternary postglacial sediments that fill the bottom of the valley and to designate the accumulation of boulders deposited on Quaternary sediments. The results of ERT surveys conducted along the axis of the valley allowed to determine the changeability of the thickness of the postglacial sediments and allowed to designate a few areas of occurrence of boulders. The ERT, GPR and CM surveys conducted across the valley allowed to designate with high accuracy the thickness of the accumulation of boulders sliding down the valley bottom from the couloirs surrounding the valley.     

Distribution of Heavy Metals in Lake Seliger Bottom Deposits

The distribution of some microelements in the surface and stratified layers of bottom sediments in Lake Seliger is studied. Data on the bottom deposit pollution by heavy metals is used to determine the anthropogenic load on the lake ecosystem. Cd, Zn, and Pb are shown to rapidly accumulate in thick (>1 m) bottom deposits that have formed during the period of lake existence. The concentrations of Cd and Zn are shown to correlate with the organic matter in thick bottom deposits.     

Specifics of Iron Migration,Transformation, and Accumulation in the Vygozero Reservoir

Iron migration forms and variations of its concentrations in water and bottom sediments of the Vygozero Reservoir were studied in period from 1993 to 2014. The decrease in wastewater volume discharged from the pulp and paper mill in the early 1990s caused stabilization of water oxidation regime and accumulation of iron in bottom sediments, from which it returns into the water mass when the environmental conditions change in the seasonal oxygen cycle.     

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....