Organic Matter In Bottom Sediments Research Articles

Determining the Consequences of Climate Change for Aquatic Ecosystems Using Bioassay Methods: a Review

The article describes the scientific and methodological possibilities of bioassay in the field of studying the effects of climate change on water bodies and aquatic organisms. In fish aquaculture, it was revealed that an increase in water temperature changes the biochemical parameters of the internal environments of organisms, affects their behavior and the number of offspring. A number of biogeochemical transformations of aquatic ecosystems are predicted: a decrease in the pH of water, mineralization of organic matter of bottom sediments, release and increase in bioavailability of compounds of potentially toxic elements. Bioassay methods using monocultures and laboratory microcosms have shown that maximum temperature values and a cascade of concomitant changes will lead to a restructuring of the aquatic life community, changes in the habitats of organisms, and the disappearance of stenothermic species. The realism of such scenarios is confirmed by paleodata and modern natural phenomena.

Bioaccumulation of Chemical Elements and Organic Carbon in the Macrozoobenthic Organisms of the Laptev Sea

Within the framework of the program “Marine Ecosystems of the Siberian Arctic”, based on the materials collected during the 69th and 72nd cruises of the R/V “Akademik Mstislav Keldysh”, a study of the distribution of a group of chemical elements (As, Ba, Bi, Co, Cr, Cr, Cd, Co, Cu, Cr, Mn, Ni, Pb, Sc, Ti, Tl, Th, V, U and Zn) and organic carbon in the mass taxa of the Laptev Sea macrozoobenthos in the fields of methane seepage and outside them was carried out. For the first time, the bioaccumulation potential (BP) was quantified, taking into account, along with the concentration of elements in organisms, their biomass. At the C-15 methane field, the population of brittle stars accumulates each of the microelements many times (up to 40 times) more than at the background station. Brittle stars and bivalves show increased BP for Ni, As, Ba, Cu, Ti, V, Mn, and Zn compared to other elements, with brittle stars having significantly higher BP. It is assumed that the increased bioaccumulation of some heavy metals and metalloids in methane seep areas is associated with a greater bioavailability of organic matter in bottom sediments. For organic carbon, the highest BP was established, which is especially expressed in the C-15 methane field. At the background station, taxa accumulate a significantly smaller (by a factor of 10) amount of carbon in their biomass. As a result of the functioning of the ground eaters, bottom sediments are enriched with organic carbon, which may indicate an important contribution of benthic organisms to the carbon cycle in the seas of the Arctic.

The Composition and Organic Matter of Bottom Sediments and Soil in the Drainage Basin Varvarinskoe Lake (Bolshoy Solovetsky Island)

The Composition and Organic Matter of Bottom Sediments and Soil in the Drainage Basin Varvarinskoe Lake (Bolshoy Solovetsky Island)

Genesis of Organic Matter in Bottom Sediments

Genesis of Organic Matter in Bottom Sediments

HYDROCARBONS IN LITTORAL SEDIMENTS AND MARCH SOILS OF THE SOUTHWESTERN COAST OF THE BARENTS SEA

According to the results of GC-MS study of the composition and distribution of hydrocarbons (n-alkanes, isoprenoids, steranes, hopanes, polycyclic aromatic hydrocarbons (PAHs) and their alkyl homologues), the genesis, facies conditions of sedimentation, the degree of transformation of organic matter of bottom sediments and marching soils of the southwestern coast of the Barents Sea are characterized. The assessment of the toxicity levels of polyarenes on the biota inhabiting the tidal zones of the coast was carried out. Areas with increased anthropogenic load have been identified (littoral of the eastern Tana Fjord, the village of Kiberg, Abram Cape, the village of Mishukovo, the mouth of the Kulonga River, the apex part of the Yarnyshnaya Bay, Oscar Bay), indicating the unfavorable ecological state of the tidal zones of the Barents Sea coast.

Gas ebullition associated with biological processes in radioactively contaminated reservoirs could lead to airborne radioactive contamination

BackgroundStorage reservoirs of radioactive waste could be the source of atmospheric pollution due to the efflux of aqueous aerosol from their water areas. The main mechanism of formation of aqueous aerosols is the collapse of gas bubbles at the water surface. In this paper, we discuss the potential influence of biological factors on gas ebullition in the water areas of the radioactively contaminated industrial reservoirs R-9 (Lake Karachay) and R-4 (Metlinsky pond) of the Mayak PA. The emission of the released non-dissolved gases captured with gas traps in reservoir R-9 was (88–290) ml/m2 per day (2015) and in reservoir R-4 (270–460) ml/m2 per day (2016). The analysis of gas composition in reservoir R-4 (60% methane, 35% nitrogen, 2.4% oxygen, 1.5% carbon dioxide) confirms their biological origin. It is associated with the processes of organic matter destruction in bottom sediments. The major source of organic matter in bottom sediments is the dying phytoplankton developing in these reservoirs. ConclusionThe obtained results form the basis to set a task to quantify the relationship between the phytoplankton development, gases ebullition and radioactive atmosphere contamination.

Influence of hydrodynamic conditions on the bacteriobenthos distribution in the upper reaches of the Zhiguli hydroelectric power station of the Kuibyshev reservoir

The paper presents the results of our expedition studies of bacteriobenthos in the water area of the Kuibyshev reservoir in the autumn period of 2020 and the influence of the dynamics of currents on its spatial distribution. The relevance of the study is determined by the need to study the internal load (secondary pollution) of large reservoirs from bottom sediments. The Kuibyshev reservoir is one of the largest flowing reservoirs in the world, where features of the coastal configuration, the heterogeneity of the bed, the unsteady hydrodynamic regime, the sediment regime and its composition determine the spatial distribution of bottom sediments and the bacteriobenthos community therein, which is an important link in the circulation processes of organic and biogenic substances in the ecosystem of the reservoir. An assessment of the regime of currents and sediments was carried out by calculation on a 2D mathematical model of the Priplotinny Reach of the Kuibyshev reservoir, implemented in the software package «VOLNA». The model was verified, and a series of numerical calculations of the flow velocity was carried out taking into account the regime of water flow control at hydraulic units. The spatial geometry of the currents and the sediment flow distribution dynamics were obtained. According to the data of our expedition studies, the total numbers and biomass of bacteria were estimated, which varied in the range of (2.47–27.55)×109 cells mL-1 and 0.10–2.43 μg mL-1, respectively. As a result of the conducted studies, patterns of the spatial distribution of the bacterial community in the water area of the Priplotinny Reach of the reservoir were revealed, and the nature of the relationship between the total numbers of bacteria and the sedimentation rate, the flow velocity, and the content of organic matter in bottom sediments was established. The influence of the circulation zones of currents in shallow waters on the nature of the distribution of bottom sediments and changes in the quantitative characteristics of bacteriobenthos is shown.

Studying the Composition and Genesis of Organic Matter in Bottom Sediments of Polluted Small Watercourses in Khabarovsk City Territory

Studying the Composition and Genesis of Organic Matter in Bottom Sediments of Polluted Small Watercourses in Khabarovsk City Territory

Marine indicators of climate change in the Azov Sea ecosystem

The study is a contemporary overview of accumulated data and knowledge about the state of water resources in the Sea of Azov basin. The focused area has been rather thoroughly studied since the 1970s, however the information presented in the literature sources is mainly in Russian. The main research objective is to consider the changes that occurred in the second half of the 20th – early 21st centuries in the lower reaches of the Don and Kuban rivers as a result of economic development of the territory (construction of water-storage reservoirs, dams, irrigation canals, etc.). We provide the most complete summary of data on the inter-annual and seasonal variability of water and solid river runoff, the nutrient load on the ecosystem of the Sea of Azov, as well as new data on the dynamics of organic carbon in the Don runoff in the recent low-water period of 2007–2020. The most significant changes include redistribution of river runoff during the year, a catastrophic reduction in solid runoff, and a change in the structure of terrigenous matter entering the sea. In conclusion, we indicate the chains of consequences of long-term changes in water, solid, and nutrient river runoff for the ecosystem of the Sea of Azov. These include changes in seawater salinity and temperature, terrigenous sedimentation, chlorophyll-a concentration, primary production values, the relative amount of organic matter in bottom sediments (one of the causes of oxygen deficiency at the bottom), structure of planktonic and benthic organisms, as well as in dynamics of valuable commercial fish populations. In particular, we discuss recent observations that confirm the earlier long-term probabilistic forecast of the collapse of the Azov pikeperch population in the beginning of the 2000s. We consider the salinity and temperature of sea waters, data on the content of diatom valves, and the appearance of the Black Sea benthic species in the ecosystem of the Sea of Azov as reliable indicators of climate change. Some of the observed phenomena are still poorly explained and require further research. Using the example of the Sea of Azov and the rivers flowing into it, we indicate how climate variability and economic activity affect the state and functioning of marine ecosystems. Some identified regularities of the processes occurring in the Azov Sea ecosystem may be applied to other water bodies (marine areas).

Studying the Composition and Genesis of Organic Matter in Bottom Sediments of Polluted Small Watercourses in Khabarovsk City Territory

The distribution of organic matter, hydrocarbons, phytopigments, and ecological-trophic groups of microorganisms was studied in the bottom sediments of ten small tributaries of the Amur R. near Khabarovsk. The water showed high concentrations of organic matter, varying from 44.47 to 279.3 mg/L. The concentration of Corg in bottom sediments varied from 1.9 to 23.1% in different types of sediments; the amount of hydrocarbons reached 5081 mg/kg, exceeding the background level by a factor of up to 50. Studies of the molecular composition of hydrocarbons in sediments revealed in some streams the predominance (up to 100% of the total) of light (C8–C13) n-alkanes, typical of oil products and the products of vegetation combustion. High-molecular compounds dominated in HC composition in most watercourses, including n-alkanes, genetically associated with terrestrial vegetation, and heavy fractions of oil products with various levels of microbial degradation. Volatile organic compounds were quantitatively dominated by the products of microbiological transformation (acetaldehyde and methanol). In terms of the concentration of sedimentary pigments (up to 400 µg/g), the sediments of the majority of watercourses belong to the hypereutrophic type. The total abundance of microorganisms in water varied from 2.7 to 488.0 thousand CFU/mL; in sediments, it was distributed symbatically, but ranged from 0.1 to 19.3 million CFU/g. The number of heterotrophic bacteria in bottom sediments correlated with the parameter of overload of the self-purification capacity (r = 0.718), and the number of oil-oxidizing bacteria correlated with hydrocarbon concentration (r = 0.967), thus confirming the indication properties of this bacterial group.

ОСОБЕННОСТИ ФОТОМЕТРИЧЕСКОГО ОПРЕДЕЛЕНИЯ ОРГАНИЧЕСКОГО УГЛЕРОДА В ДОННЫХ ОТЛОЖЕНИЯХ

Background. Organic matter in bottom sediments originates from plants and animals as a metabolic by-product; it determines biological productivity of a water body and physical and chemical properties of its bottom soils, enriches its aquatic environment with biogenic elements, and provides nutrients for its benthic communites, on which, in turn, feed benthophagous fish species. The most reprepresentative indicator of the organic matter in bottom sediments is organic carbon. Relevance. Currently, for determination of the organic carbon directly in bottom sediments, either expensive equipment or certified methods approved for soils are used. Aim. This work presents the results of development and validation of the method for quantitative determination of organic carbon in bottom sediments. Methods. The developed modification of I.V. Tyurin’s method is based on photometric detection of trivalent chrome that is equivalent to the content of oranic carbon after oxidation of the organic matter in bottom sediments in chromosulfuric acid. Chloride interference was precluded with silver sulphate; as a reference standard, the State Standard Sample of glucose was used for the first time. Results. This method has been tested on the bottom sediments of the Azov Sea, and the results are found to be in compliance with those obtained from the investigations conducted by the traditional Tyurin’s method with silver sulphate. This method does not require expensive equipment and is applicable for mass determination. Conclusion. Based on the results of this investigation, a metrological certification of the developed method has been conducted; it regulates the procedure for determination of carbon mass fractions in the bottom sediments of water bodies in the range from 0.3 to 16.0 %.

Composition and location of trophic groupings of zoobenthos in the Arctic Ocean

This study is devoted to the distribution of trophic groups of zoobenthos in the Arctic Ocean. The patterns of distribution of detritus feeders, seston feeders, and predators along the bottom of the Arctic polar basin are analyzed. The object of the study is the geoecology of the distribution of food groups of benthic animals in the polar regions. The subject of the study is the methods used in assessing the distribution of zoobenthos with different types of nutrition in the polar regions. The results of the work are based on the analysis of the vertical and horizontal structures of the distribution of benthic fauna, reflected in the map of the distribution of trophic groups of zoobenthos and systematized in the distribution table of the leading species of zoobenthos in the Arctic Ocean. To assess the patterns of geoecological distribution of zoobenthos according to the method of feeding, the following were used: actual and cartographic scientific data on the relief, soils, waters, ice cover, maps on the distribution of plankton and the content of organic matter in bottom sediments, as well as data on the trophic characteristics of the benthic fauna of the polar regions, leading biocenoses of the polar regions and geoecological conditions for the existence of benthic fauna in the polar regions. This article presents a map of the distribution of zoobenthos in the Arctic Ocean (according to literary sources), developed by the author, and a table of distribution of guide species of zoobenthos trophic groups in various areas of the Arctic Ocean, compiled by the author based on literary sources. The obtained results of the distribution of food groups of zoobenthos can be used in further detailed assessment of food reserves of bioresources in the polar regions of the World Ocean and their consumption; when designing the economic development of the polar regions; during landscape monitoring.

КАЧЕСТВЕННЫЙ И КОЛИЧЕСТВЕННЫЙ СОСТАВ УГЛЕВОДОРОДОВ ДОННЫХ ОТЛОЖЕНИЙ СЕВЕРО-ВОСТОЧНОЙ ЧАСТИ КАРСКОГО МОРЯ

The surface layer (0–5 cm) of the bottom sediments, which samples were collected during the expedition of the RV “Academician Boris Petrov” in the Northeastern Kara Sea in the summer of 2022, has been investigated. Data on the content and composition of hydrocarbons (HCs) in the bottom sediments of the investigated aquatic area have been obtained. Since oil and petroleum products are among the most common sources of pollution of the seas and oceans, it is necessary to conduct regular surveys of marine ecosystems. This work is aimed at a qualitative and quantitative assessment of HCs in the bottom sediments of the Northeastern Kara Sea and identification of their possible sources. Examination of the qualitative and quantitative composition of HCs was carried out by gas chromatography using the gas chromatograph “Crystal-5000.2” with a flame ionization detector. The quantitative determination of the total HC content was conducted by the method of absolute calibration of the FID using a mixture of HCs prepared by the gravimetric method. Chromatec Analytic 3.0 software was used to process the results. It has been found that the total amount of HCs in the bottom sediments of the Northeastern Kara Sea ranged from 25.8 to 152.4 mg/kg, being 68.21±7.76 mg/kg on average. Based on analysis of the chromatograms, the predominance of high-molecular fractions has been identified; the maximum distribution of n-alkanes was represented by homologous compounds n-C25–C29, which are the markers of allochthonous organic matter. After comparison with the calculated diagnostic indices (CPI1, CPI2, ACL, LWH/HWH, TAR, C31/C29, Paq, TMD, ΣC25–35/ΣC15–21, Pr/Ph), it was found that the increased concentrations of HCs mainly result from the natural processes and prevalence of allochthonous organic matter in bottom sediments.

Lithology and Organic Matter in Bottom Sediments of Kaliningrad Bay in the Baltic Sea

Lithology and Organic Matter in Bottom Sediments of Kaliningrad Bay in the Baltic Sea

Calculation of flows of autochtonic organic matter on the example of lake Nizhneye Barabinsky district Novosibirsk region

Fluxes of matter, especially biogenic migration of elements, are the basis for the functioning of aquatic ecosystems. Currently, no models have been developed for assessing the processes of accumulation of organic matter in small lakes, whereas they are the main accumulators of organic matter of both allochthonous and autochthonous origin. In the proposed work, the calculation of the contribution of aquatic organisms to the total sedimentation flow in a typical small lake of the forest-steppe zone of the Baraba lowland is given in order to determine the sources of the formation of organic matter in the bottom sapropel. The assessment of the current state of the ecosystem of the water body according to the characteristics of the biocenosis: benthos, phytoplankton, zooplankton, higher aquatic vegetation. The production characteristics of various links of the hydrobiocenosis have been determined. Experiments with sedimentation traps have been set up. It is shown that Lake Nizhneye is characterized by all the signs of a eutrophic lakes: overproduction of primary production with an excess supply of organic matter in bottom sediments; desynchronization in the development of producers and consumers; suppression of the pasture chain and a shift in the flow of substances and energy into the detrital chain. Sapropel in Lake Nizhny has a macrophytic-planktonic genesis, which is typical for actively swamping aging lake ecosystems of the forest-steppe region. The share of autochthonous organic matter is 34%. More than half of the sedimentation flow comes from the catchment area. The accumulation rate of sapropel can fluctuate annually depending on weather conditions and the development of producers and averages 1.25 cm per year. The extraction of sapropel and the cleaning of the lake basin from the accumulated bottom sediments can be in the future to restore the fish productivity of the reservoir.

СРАВНИТЕЛЬНЫЙ АНАЛИЗ ДОННЫХ ОТЛОЖЕНИЙ ЧЕРЕМШАНСКОГО ЗАЛИВА И ПРИПЛОТИННОГО ПЛЕСА КУЙБЫШЕВСКОГО ВОДОХРАНИЛИЩА

Different types of underlying surface of Kuibyshev reservoir watershed, morphometric heterogeneity and active hydrodynamic regime of water area determine also different composition of bottom sediments and content of organic matter in different parts of this water body. Comparative analysis of integral curves of particle-size composition of bottom sediments of Priplotinnyples and Cheremshanskiy bay showed a significant difference in the parameters of these curves. The analysis is based on the soil maps of the catchment area, bathymetric maps, the distribution field of the bottom sediments coarseness and the share of organic matter in them, as well as the velocity fields obtained as a result of hydrodynamic modeling of the water area. Comparable water areas differ fundamentally in the intensity of water exchange. Prilotinnyples is more hydrodynamically active water area, whereas Cheremshansky bay is characterized by extremely slow water exchange. At the same time, the private catchment of the tribe is represented by easily eroded light loams, dolomites and limestones. While the upper part of the private catchment area of the bay is heavily forested, and the lower part of the catchment area is composed of medium and heavy loams. All this determined the formation of bottom sediments (in the form of fine and medium sands) by bedrock and products of channel erosion of the upper and middle sections of the hydrographic network of the Cheremshanka River. Whereas fine-dispersed products of soil erosion in the private watershed of the tribe formed the bottom sediments, represented mainly by silt-silt fractions. Also well warmed extensive shallow water area of the bay creates favorable conditions for mass development of plankton community, its die-off and sedimentation in the form of detritus to the bottom. Whereas greater depth and active hydrodynamics of water masses in the Priplotinnyples determine lower content of organic matter in bottom sediments. The greatest amount of detritus is carried by current from shallow water zones and is deposited in the deep central and right bank part of the tribe.

Assessment of the Bottom Sediments State After Oil Spill

The paper has deal with the monitoring of the lake bottom sediments which were contaminated by oil during emergency spill. The results of geochemical study of chloroform bitumoids extracted from sediment samples showed that the processes of transformation of oil hydrocarbons lasted for 10 years since the oil spill. This is indicated a decrease in the residual oil content and changes in the chemical composition of bitumoids. The hydrocarbons content was decreasing and resinous-asphaltene components was increasing as oxygen-containing groups and bonds in the chemical structure of bitumoids. In the individual composition of hydrocarbons the significant redistribution of saturated hydrocarbons was occurring both within the homologous series and between different homologous series, the CPI coefficient and the biodegradation coefficient Prophy/nC17+nC18 was increasing. By 2017 in absence of new oil spills the chemical composition of bottom sediments had closed to a state inherent in the native organic matter of bottom sediments of coastal lake facies, which characterized by the presence of compounds typical for higher plant lipids (dominance of high molecular weight n-alkanes of composition nC23–nC33 with a significant predominance of odd homologues, a high content of oxygen-containing compounds – solid saturated fatty acids, aliphatic esters and saturated ketones).

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

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 presented. Patterns of the distribution of sedimentary chlorophyll a and the products of its degradation, pheopigments, depending on the water current velocity, depth and type of the bottom sediments were revealed. Taking into account the zoning of the reservoir by abiotic factors, the trophic conditions in bottom sediments were estimated by the total content of chlorophyll a and pheopigments. Average concentration of sedimentary pigments, calculated considering the areas of bottom sediments of different types, in 2009–2010 (25.3 ± 1.5 μg/g dry sediments) is less than in the years of previous observations, 1996–1998 and 2001 (59.1 and 31.9 ± 3.7 μg/g, respectively). The trophic state of the reservoir’s benthal remains mesotrophic.

The effect of humic substances on metal migration at the border of sediment and water flow

The speciation of radionuclides in bottom sediments of the Yenisei River, sampled in the near-field region of the nuclear fuel cycle enterprise, was studied. It has been established that most of 152Eu and 241Am radionuclides isolated by sequential chemical fractionation are in a bound state with the organic matter of bottom sediments (up to 35% of the total amount). In this case, the content of 152Eu and 241Am in depth of the bottom sediment layers is directly dependent on the change in the organic matter content. Bottom sediments containing a high content of organic substances (humic acids – HA and fulvic acids – FA) were studied. By the HA: FA ratio, the studied bottom sediments are related to a fulvate-humate type. When fractionating the organic matter of bottom sediments, it was revealed that the distribution occurred as follows (% of the total content): in the form of fulvates 152Eu – 53, 241Am–16, 60Co – 10, 137Cs–3; 241Am–28% associated with humin; in the form of organomineral compounds ~ 2–5%; in the form of organometallic complexes ~ 2–3%. Model experiments with addition of HA to the aqueous medium of the bottom sediments-water system. HA was previously isolated from bottom sediments and identified by IR Fourier spectroscopy. The introduction of HA significantly influenced the release of radionuclides and some metals from bottom sediments into the liquid medium. So, the content of 152Eu and 241Am radionuclides are intensively released into the water: from 0 to 198 ± 8 Bq·L−1 and 167 ± 7 Bq·L−1, respectively. The content of 4 K, 60Co, 137Cs was not considerable. The content of some analysed metals in the aqueous medium also increased significantly: 9 times for U6+ and 32 times for Cu2+.

Sources of Organic Matter in the Bottom Sediments of Small Rivers Estuaries in Basin of the Tatar Strait

The distribution of organic matter (OM), hydrocarbons, phytopigments and ecological–trophic groups of bacteriobenthos has been investigated in the bottom sediments of the internal estuaries of the small Muchke and Toki rivers. The morphological and hydrological characteristics of estuaries influence the quantitative and qualitative composition of the OM in bottom sediments. The investigation into the molecular and group composition of n-alkanes in bottom sediments has identified the main genetic types of OM closely associated with the specific hydrodynamics of waters and sedimentation in small tidal estuaries.