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.     

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.     

Analysis of the effect of copper-nickel works on the state of water resources in nearest features

The formation conditions of water exchange and quality in a lake used as a part of water disposal system of an operating copper-nickel metallurgical plant are considered. Water and material budget of the lake is calculated, including process water discharge, atmospheric precipitation, and snow melting. The quantitative and qualitative characteristics of bottom sediments and waters involved in lake water exchange are determined. The migration conditions of heavy metals from bottom sediments are evaluated and their dynamic layers are determined. Some measures are proposed for reducing the adverse impact of the coppernickel plant on water bodies.     

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.     

Effect of pore water of fine sediments on the ecological conditions of hydrosphere under oil-and-gas technogenesis conditions

Experimental models are used to study the poorly known function of pore waters, i.e., their role in hydrosphere pollution. This issue is studied as applied to modern bottom sediments, soil-forming grounds of the aeration zone, and impermeable clays in aquifers. The natural and technogenic geodynamic loads, accompanied by compaction and destruction of water-bearing rocks, are shown to intensify the processes of pore water pressing with the release of rock-forming elements, heavy metals, and organic substances into bottom water layers in water bodies, free soil or intermediate waters. This results in an environmental damage to water bodies, which could be used for drinking water supply and fishery. This study is of particular importance in areas of present-day oil and gas production.     

Toxicity bioassay of bottom sediments in large water bodies in Northwestern Russia with the use of crustaceans

The results of bioassay and physicochemical analysis of bottom sediments from large water bodies in Northwestern Russia are presented. The water bodies under consideration include Lake Onega, Vygozerskoe Reservoir, and freshwater part of the Neva Estuary (the Eastern Gulf of Finland), which are locally subject to eutrophication and toxic pollution. The potential toxicity of bottom sediments, evaluated by the survival rate of two crustacean species (Gmelinoides fasciatus and Ceriodaphnia affinis) in 7-day tests, varied from high to low values, characterizing 5 quality classes: high, good, moderate, poor, and heavy, with appropriate degrees of toxic pollution from no to very high pollution. Bad zones were identified in the Kondopoga and Petrozavodsk bays of Onega Lake, the northern and southern parts of the Vygozerskoe Reservoir, and the southern part of the Neva Bay near the dam. Bottom sediments were found to have high quality in the open central areas of Lake Onega and the Vygozerskoe Reservoir and in the western part of Neva Estuary.     

Physicochemical Properties of Bottom Sediments in Water Bodies in the Central and Southern Vietnam

Water Resources - The physicochemical characteristics of bottom sediments in inland water bodies in the Central and Southern Vietnam are presented for the first time, including particle-size...     

Oil products in bottom sediments of water bodies in Khanty-Mansi Autonomous Okrug

Concentration of oil hydrocarbons in the bottom sediments of water bodies in Khanty-Mansi Autonomous Okrug has been analyzed. Statistical methods have been used to confirm the dependence of contamination level on the frequency of accidents in oil fields. Areas with heavily contaminated bottom sediments have been singled out.Translated from Vodnye Resursy, Vol. 32, No. 1, 2005, pp. 85–89.Original Russian Text Copyright © 2005 by Moskovchenko.     

Sulfate reduction in natural water bodies: 2. Empirical models for process rate assessment

Empirical models that are used to assess sulfate reduction rates in the aquatic environment and bottom sediments of water bodies are discussed. Such models, with different detail, take into account the effect of the major habitat factors (the concentrations of organic matter, its components, and sulfates; ambient temperature; the numbers and activity of sulfate-reducing bacteria) on matter oxidation transformation during the sulfate reduction process. Improvements in the empirical models are proposed with the aim to more adequately account for the effect of environmental factors on the sulfate reduction rate distribution in water bodies. Validation of such models and the assessment of their parameters are demonstrated against available observational data collected at appropriate water bodies.     

Exchange of Mn compounds between bottom sediments and water: 1. Mn flux from water to the bed

Formation mechanisms of Mn flux from water into bottom sediments in the form of particulate matter are considered. Data characterizing Mn concentration in particulate matter, its transformation features, and the size of Mn-containing suspensions are given. Information about Mn fluxes from water to the bed of water bodies and the processes governing them are generalized.     

Space and time regularities in the distribution of dissolved and suspended manganese forms in Novosibirsk Reservoir water

The space and time regularities in the distribution, migration, and turnover of dissolved and suspended manganese forms in Novosibirsk Reservoir water are considered. The flux of dissolved manganese forms (Mn²⁺) from bottom sediments into the water mass is shown to reach its maximum in the under-ice period (since the late February to the mid-April), as well as in the period of maximal abundance of biota (August–early September), when reduction conditions form everywhere in reservoir bottom sediments. In this period, bottom sediments are the main source of manganese input into the reservoir water, their contribution reaching 250–400% relative to the inflowing river water; manganese vertical distribution in water is opposite to that of dissolved oxygen, and its concentration is in excess of the hygienic standards. The maximal flux of dissolved manganese forms (Mn⁴⁺) from water into bottom sediments is recorded in August–September (on the average, 0.17 g/(m² day)); it drops to 0.06 g/(m² day) during spring flood, and practically vanishes in the under-ice period.     

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.     

Assessment of bottom sediment contamination in acidified Karelian lakes

The physicochemical, toxicological, and teratological properties of bottom sediments in Karelian lakes (Vuontelenjarvi, Suojarvi, Venderskoe, and Chuchjarvi) and Kondopoga Bay of Lake Onega are studied. Bioassay results testify to a high toxicity of bottom sediments in heavily acidified lakes (with the water pH of 5.5 and lower).     

Oil components in the mouth area of the Don R. and in the Sea of Azov: Results of many-year studies

The data given are the results of many-year studying the distribution of the concentrations of main oil components (hydrocarbons, surfactants, and asphaltene-tarry substances) in the water mass, vertically settling particulate matter, and bottom sediment cores taken from the section Lower Don-The Gulf of Taganrog-Russian sector of the Sea of Azov in summer and autumn periods in 2006–2011. Spatial and seasonal regularities in the distributions of the total concentration of oil components and the values of their ratios in water, as well as the spatial and annual features of their accumulation in bottom sediments have been established. Radiological methods have been used for layer-by-layer dating of bottom sediment cores and determine the thickness of the layer that had formed under the maximal anthropogenic impact on ecosystems. The presence of considerable amounts of hydrocarbons of modern biological origin has been revealed in all components of examined aquatic complexes.     

Chronic pollution of freshwater bodies: Data on accumulation of pesticides,oil products,and other toxic substances in bottom deposits

The results of studies aimed to assess the information significance of the coefficients of bottom accumulation of hydrophobic organic substances and heavy metals as indicators of pollution of freshwater bodies are presented. It is shown that the same value of the coefficient of bottom accumulation may correspond to different situations in water bodies. Methods for the interpretation of data on the state of water bodies based on the coefficient of bottom accumulation and its components are proposed to reliably determine the level and character of pollution. Chronic pollution of a number of freshwater bodies of the Russian Federation is assessed by data on the accumulation of pesticides, oil products, polycyclic aromatic hydrocarbons, and heavy metals in bottom deposits.     

Toxicity assessment of bottom sediments in watercourses in Selenga River basin on the territory of Mongolia

Bioassay methods are used to assess the toxicity of bottom sediments in the main watercourses of the Selenga River basin and Lake Orog in Mongolia. Toxic bottom sediments are found in a brook in the region of the Erdenet Mining and Concentration Complex, as well as in the Eroo and Bukhlyn rivers, which experience the effect of intense gold mining. The conclusion is drawn that the Selenga River water flowing from the territory of Mongolia cannot directly affect the quality of water in Lake Baikal.     

Deterioration of eelgrass,Zostera marina L., meadows by water pollution in Seto Inland Sea,Japan

Survival of transplanted Zostera marina L. (eelgrass) and environmental conditions (water quality, bottom sediments, sedimentation on leaves and flow regime) were studied concurrently in the center, edge, and at the outside of a eelgrass meadow located in a eutrophic coastal zone in northern Hiroshima Bay, Seto Inland Sea, Japan. Eelgrass transplants at the outside of the meadow declined significantly, whereas those at the center were consistently well established. Silt content in the bottom sediments at the outside was higher than that at the center. The sediment was oxic from the surface to 2 cm deep at the center, whereas those at the edge and the outside were reductive almost from the surface. The sediment characteristics typical in eutrophic water seemed to be a factor responsible for the deterioration of eelgrass meadows. Although suspended solid concentrations in the water columns were almost the same, the amount of sediments deposited on leaves of eelgrass at the outside was higher than that at the center of the meadow. The amount of the deposition at the outside seems to be enough to inhibit photosynthesis; i.e. photosynthetic photon flux density (PPFD) available for eelgrass was only 36% of that without any deposition. The deposition in the center, however, was small enough to allow 84% of the original PPFD. Flow rates, determined at 30 cm above the bottom, a half height of average eelgrass, suggested that the rate at the outside was not enough to remove deposited sediments from the surface of eelgrass leaves. Thus, the large amount of sediment deposition caused by water pollution and/or eutrophication seemed to be another factor to inhibit the survival of eelgrass at the outside edge of the meadow.     

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.     

Persistent organochlorine residues in sediments from the Chukchi Sea, Bering Sea and Gulf of Alaska

Three surface sediments and two sediment cores were collected from the Gulf of Alaska, Bering Sea and Chukchi Sea, and analysed for persistent organochlorines (OCs). The geographical distributions of OCs showed different patterns according to their physicochemical properties. The concentrations of HCHs and HCB revealed rather uniform distribution, suggesting their more transportable nature in long-range atmospheric transport. On the other hand, DDTs and PCBs were predicted to be less transportable via the atmosphere due to the decreasing trends of residue levels in sediments from south to north. The OC profiles in the sediment core from the Gulf of Alaska which seemed to be preserved without turbation revealed the elevated residue levels from bottom to surface layers. This implies that the aerial inputs of OCs in the cold ocean are still continuing significantly. The accumulation rates of OCs into sediments were rather smaller than the atmospheric inputs, indicating that the residue levels in water bodies are unlikely to decrease rapidly in the near future.     

Coupling effects of hydrological characteristics and nutrient load in sediments on the trophic state of reservoirs

Currently,lakes and artificial reservoirs are increasingly threatened by eutrophication,which is the result of the combined action of many natural and anthropogenic factors.In the past,the effect of nutrient load on the trophic state of water bodies has attracted much attention,while few studies have addressed the effect of hydrological characteristics.Therefore,to reveal the coupling effects of hydrological characteristics and nutrient load in sediments on the trophic state of water bodies,this study collected relevant data from 36 lakes and reservoirs across China.Pearson correlation analysis showed that trophic level index was positively and significantly correlated with nutrient load in sediments and hydraulic retention time,while it was negatively correlated with mean depth and hydraulic load.The principal component analysis showed that the nutrient load was the first major component that influenced the trophic state of water bodies,followed by the mean depth and hydraulic retention time.Eutrophication was prone to occur in water bodies with mean depth less than 7 m and hydraulic retention time greater than 14 d,and the trophic level index regression equation with hydrological characteristics and nutrient load in sediments was derived by multiple regression analysis.This study revealed that the trophic state of water bodies influenced by both nutrient load and hydrological characteristics.It provides a new idea to reduce the occurrence of eutrophication in reservoirs by using the artificial hydrological regulation capacity of reservoirs.