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.     

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.     

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.     

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.     

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.     

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.     

Studying chemical exchange across the water-bed interface in Golubaya Bay,the Black Sea

The results of first application of automated bottom station for studying chemical exchange across the water-bed interface (IO RAS lander) were obtained for the case of sediments in the northwestern Black Sea near Gelendzhik (Golubaya Bay). The lander is equipped with bottom chambers, sensors of environmental characteristics, and samplers, allowing fluxes of chemical elements through the water-bed interface to be determined directly. Bottom sediments were represented by organogenous silts containing hydrogen sulfide. The high activity of diagenetic processes resulted in a higher consumption of O₂ by sediments (the flux from the bottom water was 130 mM/(m²/day), high fluxes of biogenic elements (P, Si,) and metals (Mn, Fe). At the same time, fluxes across the water-bed interface were evaluated based on the difference between concentrations of these elements in the near-bed and silt water (Fick’s law). The obtained data demonstrate the priority of direct measurements of fluxes (lander) over the calculation method. The first application of the lander suggests the need for methodological improvements both of engineering character and in chemical-analytical support.     

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).     

Strandvatn,Northern Norway,a lake with old sea-water

Lake Strandvatn, Northern Norway, was in August 1973 found to have salt water in the bottom layer. The chlorosity of the bottom water is 15.52 g/l. The tables contain hydrographical data, comparision with original sea water of the same chloride content and chemical data of the surface sediments from greatest depth.     

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.     

Subaqueous geothermal activity revealed by lacustrine sediments of the acidic Nakadake crater lake, Aso Volcano, Japan

Lacustrine sediments were sampled from the inaccessible acidic (pH = 0.43) Nakadake crater lake of Aso Volcano, Japan by a simple method. The sediments contain an extremely high content (74 wt.%) of sulfur, which exits as elemental sulfur, gypsum and anhydrite. The abundant elemental sulfur is likely formed by the reaction of SO₂ and H₂S gases and by the SO₂ disproportionation reaction in magmatic hydrothermal system below the crater lake. Based on the sulfur content of sediments and measurements of elevation change of the crater bottom, the sulfur accumulation rate at the Nakadake crater lake was calculated as 250 tonne/day, which is comparable with the SO₂ emission rate (200–600 tonne/day) from the Nakadake crater. The sediments include a small amount (9%) of clear glass shards that are apparently not altered in spite of the high reactivity of hyperacid lake water. This finding suggests that the clear glass shards are fragments of recently emitted magmas from fumaroles on the bottom of the crater lake and the magma emissions continuously occur even in quiescent periods.     

Assessment of Bottom Sediment Quality Based on Application of Statistical Methods of Data Analysis: Case Study of the Sestra River

Statistical methods of data analysis have been used to study the correlation between the benthic characteristics and the geochemical and toxicological characteristics of bottom sediments of the small river of Sestra. As shown, a relatively wide scope of biological and chemical data is needed to assess the quality of bottom sediments of the Sestra River.     

Retrospective assessment of bottom sediment condition in the Vygozero Reservoir

The results of long-term observations of the chemical composition of bottom sediments in the Vygozero Reservoir are presented. They revealed the main regularities in variation of the composition, sediment properties, and the present condition of bottom sediments. As shown, changes in the environmental conditions in the area of Vygozero influenced the processes of sedimentogenesis in the water body.     

226Ra behavior in the Pee Dee River-Winyah Bay estuary

Concentrations of dissolved²²⁶Ra in Winyah Bay, South Carolina, and in the adjacent Atlantic Ocean are augmented by the desorption of radium from sediments in the low-salinity area of the estuary and diffusion from bottom sediments. Desorption of²²⁶Ra is reflected by lower concentrations in suspended sediments from higher-salinity regions of the estuary. Bottom sediments from the high-salinity region have lower²²⁶Ra/²³⁰Th activity ratios than those from the low-salinity end.The shape of the dissolved²²⁶Ra vs. salinity profile is influenced by the river discharge. During average-discharge conditions, desorption of²²⁶Ra from suspended and bottom sediments increases the dissolved²²⁶Ra concentrations by a factor of 3.5 as the water passes through Winyah Bay. High river discharge produces an initial increase of dissolved²²⁶Ra by a factor of 2 to 3 and apparently reflects only desorption from suspended sediments. By driving the salt wedge down the estuary and reducing the zone of contact of salt water with bottom sediments, the high-flow conditions sharply reduce the flux of²²⁶Ra from bottom sediments.     

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.     

Organochlorine compounds in bottom sediments of a delta Branch of the Northern Dvina

Organochlorine compounds in bottom sediments of a delta branch of the Northern Dvina have been studied. Data on the concentration and distribution of organically bound chlorine are given. The specific features of the formation of the levels and profiles of chlorinated phenolic compounds in bottom sediments under the effect of specific primary and secondary sources in the territory of Arkhangelsk Industrial Center are demonstrated.     

Regularities in the transformation of oil pollution in watercourses based on long-term observational data

Results of long-term studies of crude oil transformations in water and bottom sediments of river ecosystems polluted as a result of oil spills are presented. Regularities in changes in the concentration ratio of hydrocarbon and resinous components of oil in water and bottom sediments under the effect of natural selfpurification processes of aquatic ecosystems are found out.     

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.