Composition Of Bottom Sediments Research Articles

EARLY DIAGENESIS GEOCHEMISTRY OF BOTTOM SEDIMENTS IN THE PLEISTOCENE CORE OF LAKE KOTOKEL (Eastern Baikal Region)

Chemical composition of bottom sediments and pore waters of organic-mineral sediments (sapropel) of Lake Kotokel (Eastern Baikal region) has been studied, based on long drilling cores, 14.5 and 16.5 m. A reduction type of diagenesis has been established, during which destruction of organic matter, transformation of the chemical composition of pore waters and the formation of authigenic minerals occur. Even in the uppermost intervals of sapropel, organic matter is being profoundly transformed and differs significantly in composition from that of bioproducers (plankton). The major role in diagenetic transformations of organic matter belongs to different physiological groups of microorganisms, primarily heterotrophic, amonifying and sulfate-reducing bacteria. During diagenesis, the basic chemical composition of pore waters (HCO3–, SO42–, Cl–, Ca2+, Mg2+, K+, Na+) changes, trace elements (Fe, Mn, Sr, Ba, Pb, As, Co, Ni) redistribute, concentrations of HCO3–, NH4+, PO43− and Si increase; this is caused by destruction of organic matter. In the process of bacterial sulfate reduction in pore waters, the concentration of SO42– decreases along the depth of the section, and in the sediment the proportion of reduced forms of sulfur increases and the isotopic composition of sulphur δ34S changes. Transformation of chemical composition of pore waters and the activity of microorganisms leads to the formation of authigenic pyrite, rhodochrosite, and barite.

Sediment microbial communities of a technogenic saline-alkaline reservoir

Various natural saline and alkaline habitats have recently been widely investigated, but knowledge of anthropogenic habitats with more complex environmental conditions is still lacking. This research looks at the structure of microbial communities in 18 bottom sediment samples from a technogenic water body with saline and alkaline composition. The core samples were collected from 2 columns in the western and eastern parts of an artificial water body at the Verkhnekamskoe Salt Deposit (Russia). The microbial community structure was studied using high-throughput 16S rRNA gene sequencing. The bottom sediment composition (salinity, pH, and toxic element content) varies greatly with depth and laterally throughout the study area. The study found a considerable difference in bacterial community diversity between the 2 columns, but no considerable difference was found between the communities at various depths of the studied layers. Proteobacteria, Firmicutes, and Actinobacteria, which are common in both natural and artificial saline and alkaline environments, make up the majority of the bacteria found in the samples. Studies have shown that salinity and total alkalinity are the key factors influencing the formation of microbial communities. Ralstonia and Pseudomonas were the two most common genera in the sediment samples. These two genera are known for having high metabolic flexibility, which means they can survive in extreme environments and use a variety of carbon compounds as energy sources. The study also found that Ralstonia is indicator bacteria in samples with the highest concentrations of toxic elements compared to the other samples. A relatively high microbial diversity was discovered in the studied anthropogenic water reservoir despite the extreme alkaline and saline conditions, but it is considerably lower than that found in natural, less alkaline habitats. This research offers insight into the mechanisms behind microbial community formation in complex anthropogenic environments and covers key factors in microbial community distribution.

ELEMENTAL COMPOSITION OF BOTTOM SEDIMENTS AND PERMAFROST DEPOSITS FROM THE BUOR-KHAYA BAY (LAPTEV SEA)

The paper summarizes data on the lithological and elemental composition of bottom sediments and permafrost from boreholes 1D-14, 3D-14 and 1D-15 drilled in Buor-Khaya Bay in 2014-2015. Based on the results of determining the percentage content of SiO2, Al2O3, Fe2O3, TiO2, MgO, Na2O, K2O, CaO, MnO, P2O5, Cl, Cr, S, Ni, Cu, Zn, Rb, Sr, Ba, Y, Zr, organic carbon in sediments, lithochemical modules values were calculated and comparative analysis of the lithological and geochemical composition was performed. Principal differences between near-continental (1D-14 and 3D-14) and relatively distant from land (1D-15) strata were established, which is explained by spatial and temporal variability in sedimentary fluxes and weathering crust activity in the studied area of the Laptev Sea. The results of the study allowed to conclude that the basis of the petrofund of the studied deposits are most likely sedimentary rocks of the Kharaulakh ridge of the Verkhoyansk mountain system (sandstones, siltstones and mudstones). The contribution of igneous and metamorphic rocks to the sedimentary supply in the strata uncovered by drilling was insignificant.

Reconstruction of the geochemical evolution of the saline lake Shira (Southern Siberia, Russia) in the late Holocene

The paper presents reconstruction of the geochemical evolution of the saline lake Shira (South Siberia, Russia) over the past 3000 years based on the elemental composition of bottom sediments. Based on the rock-forming element contents obtained by X-ray fluorescence analysis, the main geochemical indices were calculated to assess the degree of deformation and weathering of the rocks in the catchment basin, paleosalinity, paleoclimate, paleoproductivity and input of clastic materials. Changes in Al2O3 and TiO2 contents reflect the influence of the terrigenous contribution in the lake basin and demonstrate four decreases in the terrigenous removal contribution in the age intervals of 40-135, 580-800, 1900-2020 and 2780-2850 cal. a BP. These intervals are characterized by decreases of Na2O, SiO2, K2O and Fe2O3 contents and increases of MgO and CaO contents. The deceleration in the processes of physical weathering of terrigenous material from banks into the lake and its removal by watercourses is confirmed by the increase of the paleosalinity index and the decrease of chemical weathering. The four considered intervals are characterized by high values of the Ti/Zr ratio, which corresponds to rocks formed close to the provenance area. For the interval 2780-2850 cal. a BP, the change of the Ti/Zr ratio value is not so contrasting in comparison to the intervals 40-135, 580-800 and 1900-2020 cal. a BP. The mineral composition of the bottom sediments of saline lake Shira corresponds to young and immature clay mineral with a high percentage of primary silicate minerals, formed under cold climate conditions.

Okenone and other fossil photopigments from the bottom sediments of Lake Shira, as a proxy of recent changes in the hydrological regime of the lake

Studying the pigment composition of bottom sediments of the meromictic Lake Shira allows us to learn about the past of the reservoir. Analysis of carotenoids of frozen cores of the upper layers of bottom sediments, and comparison with field observations shows the relationship between the hydrological regime of the lake and the content of okenone, a carotenoid of purple sulfur bacteria.

Correlation of small isolated reservoirs in the Zaonezhsky Peninsula area with the Onega Ice Lake level changes

The article discusses data on the lithological composition of bottom sediments from two small lakes – Lake Lavkozero and Lake Gangozero, located on the Zaonezhsky Peninsula, within the area of the Onega Ice Lake. In the recovered sediment sequences from studied lakes, two sediment units from top to down have been recognized: Holocene gyttja from small isolated lakes and Late Pleistocene sediments from the Onega Ice Lake, which are represented by varved clays and silts. Based on lithological data, a “pink horizon” of varved clays was identified. It is similar to one which found in the sediment section of the Unitskaya Bay in Lake Onega. The absolute hypsometric position of this “pink horizon” was determined based on the elevation levels of the lakes under study.

New Data on the Mineral and Geochemical Composition of Bottom Sediments in the Tanatar Soda Lakes (Kulunda Plain, Russia)

The lakes of the Kulunda plain have long attracted the attention of researchers. A detailed 10 geochemical testing of a chain of four small soda lakes of the Tanatar group allowed answering a 11 number of questions. We used a complex of modern methods of mineralogy and geochemistry to 12 update and add new data on the main phases of bottom sediments. The studied lakes have a pH ≥ 8 13 and a TDS of 2.1–41.5 g/L and a soda water composition. It has been established that over the 14 past ∼ 100 years there has been no change in the mineral composition of bottom sediments. The 15 main phases of the bottom sediments consist of intermediate and high – Mg calcite and Ca-excess 16 dolomite. Magnesite is presented only as a small impurity. The formation and accumulation of these 17 minerals occur throughout the core of bottom sediments. According to received data, a change in the 18 hydrological regime of the catchment area was established. The feeding regime of the lakes has been 19 changed because of the drying up of the Rublevaya River.

Client-Server Application for Automated Estimation of Bottom Sediment Composition in the Fraction >0.1 mm from Microphotography Using Modern Deep Learning Methods

Client-Server Application for Automated Estimation of Bottom Sediment Composition in the Fraction >0.1 mm from Microphotography Using Modern Deep Learning Methods

Chemical and Microbiological Composition of Tom River Bottom Sediments (Yurginskii District, Western Siberia)

Data of chemical and microbiological analyses of bottom sediment composition of the Tom R. near Yurga Town, Kemerov oblast, are given. All samples of bottom sediments were found to contain organic compounds of mixed, biogenic, and anthropogenic origin with the predominance of the latter. Clayey and silty bottom sediments show a higher content of ash-free substance, heavy metals, practically all classes of identified hydrocarbons, except for oxygen-containing and acyclic compounds. Bottom sediments with sand composition contain minimal concentrations of organic pollutants, and the proportions of hydrocarbons of different origin in them are comparable. Microbiological analysis showed the predominance of hydrocarbon-oxidizing bacteria in bottom sediments composed of clays and silty sand.

An Investigation of the Chemical Composition of Bottom Sediments from Dried Lake Gavur of Türkiye by Using XRF and Multivariate Data Analysis

Lake sediments offer valuable information about the geographical, climatic and environmental changes. This work examined the chemical elements of eleven sediment samples from the old bottom (0-5m; 0.5m increments) of the dried Lake Gavur in Türkiye by applying XRF along with PCA and PLSR data analyses. The highest but negative correlations were observed for Sr (-0.89), S+SO3 (-0.74) and Zr+ZrO2 (-0.61) with sampling depths meaning that their concentrations were lower in deeper locations (4.0-5.0 m). In contrast, Ti+TiO2 (0.60), Al+Al2O3 (0.53) and Cu+CuO (0.51) had high and positive correlations and their quantities increased as the depth increased. The age of two samples was determined as 4752±33 BP years (2.5 m) and 5470±35 BP (5.0 m). Ca+CaO content was found as lower and Ti+TiO was higher in the deeper sediment (5.0 m) indicating rainy periods. PCA clustered the samples into two groups as deeper samples (4.0-5.0 m) and other samples (0.0-3.5m) while PLSR grouped them into three clusters as deeper (4.0-5.0 m), medium-depth (1.5-3.5 m) and shallower (0.0-1.0m) samples. PLSR model had a good performance to estimate the sampling depth from the chemical elements (R2cal=0.95; R2val=0.67) which means that the variations of the chemicals were highly dependent on the sampling depth.

BOTTOM SEDIMENTS OF SURFACE WATERCOURSES OF THE MALMYZHSKY MOUNTAIN RANGE

X-ray fluorescence, electron microscopic, sedimentation analyses and laser diffractometry methods were used to study the composition of bottom sediments of surface watercourses of the Malmyzhskaya Ridge section allocated for the construction of a mining and processing plant (Khabarovsk region, Russia). It is established that the bottom sediments of the coastal zone of the watercourses of the studied area are characterized by a similar gross composition and physical and chemical properties (pH, solid phase density, total carbon content, wetting edge angle CAW). Th ey are mainly represented by fine earth with a high proportion of suspended sediments, in which the fraction of coarse silt prevails (particle size <2,0 mm, <0,1 mm and 0,01-0,05 mm, respectively). It is shown that deforestation in the sources of watercourses accompanied by soil erosion leads to a significant increase in the dispersion of sediments (an increase in the proportion of suspended sediments up to 90%) in the upstream. Downstream, with the distance from the felling sites, the infl uence of deforestation on the dispersion of deposits fades. Th e content of suspended sediment is reduced to values characteristic of watercourses in the catchment area of which deforestation has not been carried out. Significant microaggregation of suspended sediments of watercourses was revealed, the participation of microbiota (testate amoebas of xenosome taxa, diatoms and Fereducing bacteria) in the formation of microaggregates was diagnosed. Th e latter are involved in the formation of vivianite on the surface of ferruginous-clay microaggregates with an increased content of phosphates after fires. The mechanism of formation of toroidal microforms of vaterite in bottom sediments with the participation of cyanobacteria of the Spirulinaceae family is proposed.

Current Hydrological Conditions Research of the Chaika lake System in the Territory of the Volga-Akhtuba Floodland

The nature protection measures performed within the national project "Ecology" on the lake system "Chaika" were analysed, the flooding status of the floodland before and after the measures implementation was compared with the equivalent special spring release. A positive effect in increasing the floodland area was confirmed. The chemical analysis results of water and composition of bottom sediments were presented. The bottom sediment was found fertile to be classified as calc-sapropel.

The Genus <i>Hydrocharis</i> L. (Hydrocharitaceae): Community Ecology, and Tolerance to Abiotic Factors

The genus Hydrocharis L. combines free-floating, occasionally rooting obligate pleistophytes and rooting hydrohelophyte, which are edificators and subedificators in freshwater vegetation communities. How ecologically similar are these closely related species? It has been found that Hydrocharis dubia (Blume) Backer. and H. morsus-ranae L. are conditionally freshwater alkaliphilic mesoeutrophic, ortho-, mesoalluviophilic detrito-, psammopelophiles. Ecologically H. chevalieri (De Wild.) is isolated, it is a freshwater acidoneutrophilic meso-, mesoeutrophic, ortho-mesoalluvialophilic species indifferent to the mechanical composition of bottom sediments. The coenocomplex of H. chevalieri is characterized by abundance of helophyte communities; in the composition of the coenocomplex of two other species hydatophyte and pleistophyte communities play a key role. Communities with species of the genus Hydrocharis are characterized by simple synmorphology, relatively high species richness, and a high proportion of low-abundance species.

Large-Scale Variation in Diversity of Biomass-Dominating Key Bryozoan Species in the Seas of the Eurasian Sector of the Arctic

An analysis of archival and literary materials, as well as recently collected data in coastal areas at 14 locations in the Eurasian seas showed that the diversity of biomass-dominating key bryozoan species is low, totaling 26 species, less than 1/15 of the total bryozoan fauna richness. Their number decreases eastward from 17 species with an average total biomass of >16 g/m2 in the Barents Sea to three species with an average biomass of about 3 g/m2 in the East Siberian Sea. In the Chukchi Sea, their number and average biomass increase to 10 species and ~12 g/m2, respectively. Average biomass strongly correlates with the number of species in each sea. Furthermore, variation in biomass is significantly correlated with the composition of bottom sediments and, in some locations, with depth. The marked decrease in the number of key species along the vector from Barents→Kara→Laptev→East Siberian Sea is due to a decline in the number of boreal and boreal–Arctic bryozoans of Atlantic origin. In contrast, the appearance of boreal and boreal–Arctic Pacific species is responsible for the increase in key species in the Chukchi Sea.

ПРИРОДНЫЕ УСЛОВИЯ И РЕЛЬЕФ ДНА ЗАЛИВА АКАДЕМИИ (ОХОТСКОЕ МОРЕ)

A comprehensive analysis of the field data and findings from previous studies made it possible to refine the bottom morphology of the Academy Bay. Environmental conditions of the Shantar region were considered. Natural factors that determine differences in morphodynamics of individual parts of the Academy Bay were revealed. The relief and relief-forming processes were described. Denudation and alongshore sediment transport were found to predominate. The accumulation of recent sediments is confined to the heads of bays and estuaries. Differences were revealed in the distribution of minor relief features and the composition of bottom sediments in parts of the Ulban, Konstantin, and Nikolai bays, which was predetermined by a complex system of sea currents. Fluvial erosion was found to occur as both linear - valley and isometric depressions that are more widespread in the Academy Bay and larger in size than in the earlier studied Tugur and Uda bays. The morphodynamic zone distribution of the bay bottom yielded four zones differing in manifestations of present-day exomorphogenesis. Their description is presented. Findings of the research can be used for follow-up studies and for the purposes of economic development of the region.

Hydroecological indicators of Lake Bolshoy Sarykol, Karaganda region

The work studied the general ecological state of Lake Bolshoy Sarykol in the east of the Abay district of Karaganda region. Morphometric measurements of the reservoir, studies of samples for hydrochemical composition, composition of bottom sediments, diversity and quantitative indicators of coastal aquatic vegetation, diversity and quantitative indicators of phyto- and zooplankton, benthic organisms and fish populations were carried out. The results of studying the content of sulfates in bottom sediments and mobile sulfur indicate active sulfate reduction. According to hydrological data, the lake of the steppe zone Bolshoy Sarykol is experiencing its high-water period. The water in the lake is slightly brackish, sodium-hydrocorbanate-chloride type, the acidity is neutral, slightly alkaline without harmful impurities, favorable for fishery reservoirs. The species diversity of Lake Bolshoy Sarykol is mainly represented by widespread species of planktonic and benthic organisms, nekton and determines the mesotrophic type of trophism, as well as the β-mesosaprobic type of eutrophication. The results of the work can be useful for the development of measures and recommendations aimed at the rational use and protection of water resources in the Karaganda region, since the studied water body is a typical lake for this region.

Granulometric, elemental and isotopic composition of bottom sediments of lakes of mountainous areas as a reflection of transformations in their watersheds

The article provides a brief description of the geological and tectonic structure and technogenic transformations in the drainage basin of two lakes of the Krasnodar Krai (Malyy Liman and Abrau). They belong to a single natural-technogenic system. On the example of these mountain lakes, the grain-size distribution, elemental (mercury) and isotopic (cesium-137) composition of bottom sediments was studied. The use of a set of methods and technologies, including those developed by the authors, made it possible to determine the parameters of the anthropogenic impact layer in bottom sediments and the chronology of its formation. It is closely related to natural and man-made events in the drainage basin.

Перспективные методы обнаружения субмаринной разгрузки в Балтийском море и опыт их применения

Submarine discharge of groundwater (SDGW) is a hydrological process that typically occurs in coastal areas and is defined as the underwater inflow of fresh and brackish ground­water from the continent to the sea. The discharge of waters with a composition sharply differ­ent from seawater leads to the formation of hydrochemical anomalies in the near-bottom hori­zon and alters the composition of bottom sediments. Under different regional conditions, dis­charge can occur as a focused flow through cracks in karst and fissured rocks, as a diffuse flow in loose deposits, or through the recirculation of seawater in bottom deposits. Therefore, it is essential to consider local geological and hydrogeological conditions, as they can significantly influence the character and distribution of groundwater and, consequently, the possibility of submarine discharge and the likelihood of its detection. Despite the ubiquity of the SDGW process in the continental shelf zone, practical detection is often a challenging task. The aim of this study is to identify approaches that best allow for documenting the phenomenon of sub­marine discharge of groundwater in the southeast part of the Baltic Sea. Detecting submarine groundwater discharge in the Baltic Sea is crucial for understanding the processes in the wa­ter body and evaluating the ecological situation. The study examines various methods for detecting SDGW: computational-analytical, geophysical, radioisotopic, chemical, and biologi­cal. The expe­rience of their application in the southeastern Baltic Sea is characterized, allow­ing for the identi­fication of areas where submarine discharge of groundwater from Jurassic and Cretaceous hori­zons occurs. The conclusion is drawn that for effective detection of sub­marine discharge foci, a comprehensive approach involving various research methods is neces­sary.

Study and evaluation of the chemical composition of bottom sediments of the Volga-Akhtunisky flood

The chemical composition of the bottom sediments of the Volga-Akhtuba floodplain was assessed. Chlorides (36 mg/kg) were found to be one of the predominant anions, while calcium (27 mg/kg) and sodium (27 mg/kg) were the predominant cations. In terms of pH, the bottom sediments were weakly alkaline throughout the studies. The agrochemical composition of bottom sediments of the studied water body corresponded to lime sapropel due to the content of organic matter in them (4.21%), as well as common forms of nitrogen (0.58%), phosphorus (0.27%) and potassium (1.1%). To assess the chemical and toxicological parameters in samples of bottom sediments, the quantitative content of metals and pesticides was determined. It was found that their content does not exceed the maximum permissible concentrations. An analysis of the IR spectrum data made it possible to establish that the IR spectrum contains absorption bands characteristic of bentonite clays, which have good fertilizing and water-retaining properties.

The Effect of Accidental Spill of Diesel Fuel in Noril’sk on Hydrocarbon Concentrations and Composition in Bottom Sediments

The Effect of Accidental Spill of Diesel Fuel in Noril’sk on Hydrocarbon Concentrations and Composition in Bottom Sediments