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A sorbent with magnetic properties, functionalized with humates, in combination with gas chromatography–mass spectrometry is proposed for the determination of phenolic xenoestrogens (ED) in bottom sediments. The octylphenol (OP), nonylphenol (NP), and bisphenol A (BPA) ED are chosen as test samples. Along with ED, the distribution of the naturally occurring estrogen, 17β-estradiol (ES), is studied. Sorption preconcentration is carried out under dynamic conditions: a sorbent weighing 0.5 g is placed in a borosilicate glass column, on both sides of which magnets are placed to immobilize the sorbent. The analytical characteristics of the determination method are established using model samples of bottom sediments selected in a background area with a minimal anthropogenic impact. The limit of quantification for ED is 30–60 ng/kg (dry weight). In analyzing real samples, the sensitivity of the method is reduced by 3–4 times due to matrix effects of the presence of petroleum products in waters. The ED content of bottom sediments at the site of wastewater discharge into the river Don near the city of Voronezh, as well as on the Black Sea coast of the Caucasus (area of the city of Tuapse and the village of Olginka) was monitored. The maximum concentrations of OP, NP, BPA, and ES in bottom sediments were found in the area of the port of Tuapse, where they were 5.7, 8.1, 6.2 and 0.9 µg/kg, respectively. [ABSTRACT FROM AUTHOR]

An original bench-scale installation based on the principles of online magnetic solid-phase extraction is developed. The setup includes a borosilicate glass column packed with Fe3O4@MIP-BPA, which is fixed with two neodymium magnets. Compared to using one magnet, a design with two magnets ensures the uniform distribution of the sorbent over the entire cross-section of the column. The highest concentration factors (EF = 3216) and the degree of desorption of bisphenol A (BPA) are achieved, respectively, at a volumetric solution flow rate (W) of 2.0 mL/min and with eluting BPA with methanol (W = 0.4 mL/min). The determination of BPA in concentrates from model media by GC−MS provides high sensitivity of the developed method for determining BPA. In analyzing model solutions prepared in distilled water, the limit of detection (LOD) is 0.3 ng/L. In analyzing river water, the LOD increases by approximately 2 times. In analyzing soils, LOD = 2.2 ng/kg dry weight. Soils, compared to water bodies, contain a larger number of interfering components; the sensitivity of the method is reduced by 7–8 times. Bottom sediments are even more contaminated; the LOD more than doubles compared to the determination of BPA in soils. [ABSTRACT FROM AUTHOR]

The microbial communities of bottom sediments of the Bolshaya Zelenovskaya oil seepage site (Lake Baikal) were investigated to assess their diversity and potential functional activity in the anaerobic degradation of oil. Microorganisms of the subsurface and deep sediment layers were grown in enrichment cultures supplemented with oil and various electron acceptors for 1 year at 10°C, and it was found that the concentrations of n-alkanes and polyaromatic hydrocarbons decreased by 1.2–2 and 2.2–2.8 times, respectively. Hydrocarbon conversion was accompanied by generation of hydrocarbon gases (methane and ethane). The microbial community of subsurface sediments had a higher bacterial diversity than the community of deep horizons and was composed of microorganisms specialized in degradation of a broad range of substrates, including oil hydrocarbons. The community of the deep sediment layer was dominated by Atribacterota, Caldisericota, and Bathyarchaeia (Thermoproteota), as well as members of the "rare biosphere": Elusimicrobiota and Candidatus Hadarchaeota. Apparently, oil degradation in the bottom sediments of Lake Baikal is primarily mediated by members of the phyla Bacillota, Pseudomonadota, Chloroflexota, Actinomycetota, Desulfobacterota, Atribacterota, Halobacteriota, and Bathyarchaeia (Thermoproteota). [ABSTRACT FROM AUTHOR]

The results of the study of bottom sediments and water of the estuary of the Grøndalen River (Grøn-Fjord, West Spitsbergen) are presented. The stratigraphic features of the sedimentary strata are determined. The chronology of changes in geoecological environmental conditions has been established using radioisotope dating methods. The main factors influencing sedimentation in the study area are air temperature and precipitation during the period of predominance of low temperatures. It is shown that climate fluctuations determine the chronological sequence of the sedimentation rate and the change of the lithotype of the bottom sediment toward fine fractions. [ABSTRACT FROM AUTHOR]

Lake Konin is a small and shallow lake under the influence of highly eutrophic riverine waters. Feeding the lake as a backwater during high water level periods, the River Obra had exerted a decisive impact on lake water quality, and thus a new dike with a closing device was created. Protective measures were followed by the application of Effective Microorganisms (EM), aiming at a reduction in nutrient concentrations and CyanoHABs. Positive changes in the ecosystem were initiated (increased phytoplankton diversity), but cyanobacteria blooms were still present due to high nutrient content. Some changes were observed in the lake sediments (phosphorus (P) and its fractions, P in pore waters, organic matter and experimental assessment of internal P loading) studied before and during treatment. A slight increase in P content in sediments was noted, as a result of an increase in the Res-P fraction. Simultaneously, a decrease in the most mobile fractions was observed. Summer internal P load was reduced from 5.4 kgP d−1 before the treatment to less than 1 kgP d−1 in the first year, but increased again in the second year to 4.5 kgP d−1. Similarly to lake water quality, positive changes were induced in the lake sediments; nevertheless, they still acted as an important source of nutrients for primary producers. Additional restoration methods shall be considered, as combined treatments used simultaneously are reported to be the most effective for water quality improvement. [ABSTRACT FROM AUTHOR]

The assessment of the spatiotemporal dynamics of biogenic element accumulation in the bottom sediments of a trout farm located in the northern part of Lake Ladoga was conducted for the first time. Sediment cores were sampled during different hydrological seasons both near the fish cages and at a distance from them. Analyses of total nitrogen and labile phosphorus compounds in the sediments were conducted layer by layer. The dependence of biogenic element content on the organic matter content in the bottom sediments was analyzed. The results showed that the temporal dynamics of biogenic element accumulation in the bottom sediments in the area influenced by the trout farm were closely related to the seasonal feeding intensity of the fish cages. The increase in biogenic element content in the bottom sediments, resulting from the functioning of the fish farm, did not affect the control points. The seasonal formation of an anaerobic reducing environment in the surface layer of sediments may contribute to the increased influx of the studied elements from the bottom sediments into the water column. [ABSTRACT FROM AUTHOR]

Biomarkers of the presence of animals and humans (fecal stanols) are well preserved in lake sediments. They are produced by intestinal microflora from sterols. Coprostanol and epicoprostanol are specific human stanols, since they are produced in the greatest quantities when compared to animals. These stanols are used to reconstruct the population history of water bodies. In this work, fecal stanols have been studied for the first time in the bottom sediments of Lake Zapovednoye, located in Evenkia (Siberia, Russia). The analysis is carried out using a gas chromatograph with a mass spectrometric detector. Along the entire core, there are no pronounced signals of coprostanol and epicoprostanol compared with other stanols, which indicates a negligible contribution of humans to the pool of fecal stanols. It is obvious that throughout the entire studied time interval (up to 2500 years ago) there were no permanent settlements in the lake's drainage basin, which is generally consistent with the extremely low population density of this region and unfavorable living conditions. [ABSTRACT FROM AUTHOR]

The cartographic landscape analysis of Lake Doshne employs geographic landscape methods, GIS cartographic modeling, and geo-ecological analysis. This study includes hydrochemical analysis of the lake's water mass, focusing on saline blocks, tropho-saprobiological indicators, and specific toxic action indicators. Three geological sections of anthropogenic and pre-Quaternary complexes, along with a geological–lithological transverse profile of the lake basin, were developed. Additionally, a geographical landscape model of the lake's natural aquatic complex was presented, distinguishing littoral–sublittoral and profundal aquatic sub-tracts and five types of aquafacies with landscape metric assessments. This approach enables a comprehensive analysis and the creation of cartographic models that can serve as a basis for lake cadastre and optimization of the ecological and landscape conditions in local territories. [ABSTRACT FROM AUTHOR]

Studies of volatile organic compounds (VOCs) emitted from the bottom sediments of three Pomeranian lakes in Poland: Łazienkowskie, Rychnowskie, and Jeleń were conducted. All three lakes are subject to anthropogenic pressure but to varying degrees. In 2021, bottom sediment samples were taken from the lakes studied and an analysis of the emission of 20 volatile organic compounds was carried out using a proton transfer reaction mass spectrometer (PTR-MS). Concentrations in emissions from the bottom sediments of VOCs with the following mass–charge ratio (m/z) were analyzed: 57, 61, 63, 69, 75, 81, 83, 85, 87, 95, 97, 99, 101, 109, 111, 127, 129, 137, 149, and 157. The obtained data were analyzed by performing statistical tests and multivariate cluster and PCA analysis. The analysis shows that the lowest concentrations of VOCs were observed from bottom sediments in Lake Jeleń, which is subject to the lowest anthropopressure among the studied lakes. The analysis shows that the lowest concentrations of VOCs were observed from bottom sediments in Lake Jeleń, which is subject to lower anthropopressure among the studied lakes. With the help of cluster analysis, it was possible to collect data on the VOC concentrations into clusters, which resulted in demonstrating similarities between Łazienkowskie and Rychnowskie lakes—lakes connected by an isthmus, and the different characteristics of Lake Jeleń. PCA analysis leads to similar observations. The tested m/z VOCs can be identified using additional analytical methods. [ABSTRACT FROM AUTHOR]

A composite based on Fe3O4 nanoparticles, graphene oxide, and a ionic liquid (1-butyl-3-methylimidazolium-2-carboxylate) is proposed as a sorbent for the extraction of bisphenol A (BPA) from bottom sediments by matrix solid-phase dispersion (MSPD). The saturation magnetization of the synthesized sorbent is 34 emu/g. Grinding of bottom sediments and subsequent grinding with a sorbent was carried out in a ball mill. Some stages of MSPD were partially automated, in particular, the procedures of magnetic separation, BPA desorption, and sorbent regeneration. The recovery of BPA under the experimentally selected conditions (sorbent mass 0.5 g, time required to grind the sorbent 5 min) was 94%. The sorbent can withstand four sorption-desorption cycles without a loss of sorption capacity. To purify the matrix from interferents, washing with n-heptane was proposed. Bisphenol A was determined by gas chromatography–mass spectrometry after derivatization with acetic anhydride. The analytical characteristics of the method were established using model samples of bottom sediments artificially contaminated with BPA. The limit of determination using the developed method is 0.1 μg/kg, the linearity range of the calibration curve is 0.3–12 μg/kg (r2 = 0.994). As real samples for analysis, we used bottom sediments selected near the discharge of wastewater treatment plants in the city of Voronezh (Voronezh River and Don River). The BPA concentration in bottom sediments is 3.83–6.52 μg/kg. [ABSTRACT FROM AUTHOR]

The content and distribution of precious metals in fine-grained bottom sediments, accumulated in the technogenic period (last decades) in the southwestern part of the Chukchi Sea, have been studied. The ubiquitous or local enrichment of the sediments with silver, gold, platinum, and palladium according to the average for the Earth's crust, as well as their enrichment with gold and palladium relative to pre-technogenic (Late Holocene) deposits, was shown. Differences in the conditions of the accumulation of precious metals in the Late Holocene and modern sediments were shown. Sources of input were determined, and the possibility of technogenic enrichment of the sources was proved by the methods of multicomponent statistical analysis of the total chemical composition of the sediments. [ABSTRACT FROM AUTHOR]

The cartographic landscape analysis of Lake Doshne employs geographic landscape methods, GIS cartographic modeling, and geo-ecological analysis. This study includes hydrochemical analysis of the lake’s water mass, focusing on saline blocks, tropho-saprobiological indicators, and specific toxic action indicators. Three geological sections of anthropogenic and pre-Quaternary complexes, along with a geological–lithological transverse profile of the lake basin, were developed. Additionally, a geographical landscape model of the lake’s natural aquatic complex was presented, distinguishing littoral–sublittoral and profundal aquatic sub-tracts and five types of aquafacies with landscape metric assessments. This approach enables a comprehensive analysis and the creation of cartographic models that can serve as a basis for lake cadastre and optimization of the ecological and landscape conditions in local territories.

Heavy metal pollution of the bottom sediments in the Northern Caspian Sea region was assessed for the period from 2012 to 2021. The concentrations and pollution levels of heavy metals were determined using the standard indices as part of the industrial environmental monitoring at the license site in the northern part of the Caspian Sea. Based on the concentrations of all identified metals (zinc, copper, lead, cadmium, nickel, iron, and manganese), significant spatial and temporal variations were observed. The values obtained did not exceed those of international sediment quality standards, thus suggesting that the studied bottom sediments were only slightly polluted by heavy metals. However, certain areas showed high levels of pollution, such as the northwestern area with the elevated iron levels and the central area with the maximum lead and cadmium concentrations. The statistical analysis of geochemical parameters of the bottom sediments revealed distinct patterns in the distribution of heavy metals.

We compared the arithmetic average chemical composition of main types of Pleistocene sediments in the Indian and Atlantic oceans, and average chemical composition of the Pleistocene in both oceans as well. As the base for comparison, we used data from the International project of deep-sea drilling reports (phases DSDP, ODP, IODP) and other references. It was revealed that the results of comparative analyses of the mean weighted chemical composition were determined by masses of the dry sediment matter. Domination of the Atlantic mass accumulation rates over the Indian Ocean ones was due to markedly larger catchment areas, influence of more significant humid climate, and enhanced primary production. [ABSTRACT FROM AUTHOR]

Representative sets of biotic and abiotic parameters were taken from maps of their distribution at the sea bottom, using interpolation. Good correspondence between real and modeled data was noted that allowed to engage the latter for correct estimation of the mean explained variance (MEV) by regression analysis. The magnitude and structure of MEV variability depended on external influence that proves possibility of its application as a measure for total effect of abiotic factors. Among many variants of the ecological stress index (PES), the more convenient for modeling was that one with the maximum correlation between distribution density or biomass of certain taxa and the total density or biomass of macrozoobenthos at stations (in samples). This approach provides better biological plausibility, as well, so as the benthic dwellers, like other animals, are very diverse in size and interspecific relations, that’s why the distribution density of a species correlates well with either total density or total biomass, and the same for biomass of a species. Results of in situ studies of PES dependence on MEV were confirmed by modeling with virtual MEV values. The difference between real and modeled PES values was statistically insignificant, but the MEV ranged wider in the models with virtual values and the dependence curve had weaker inflection when reached a plateau. The final dependence is S-shaped (r2 = 0.939), with the greatest curvature at 85.4 % of MEV (PES of 15 %), and the point of minimum or beginning of growth (beginning of the model curve plateauing) at 94.0 % of MEV (PES of 36 %). These levels are critical for macrozoobenthos communities. The PES level for the 2nd critical level was previously estimated as 30 %, but this value was corrected to 36 % by calculation with biologically more reasonable method.

Studies of volatile organic compounds (VOCs) emitted from the bottom sediments of three Pomeranian lakes in Poland: Łazienkowskie, Rychnowskie, and Jeleń were conducted. All three lakes are subject to anthropogenic pressure but to varying degrees. In 2021, bottom sediment samples were taken from the lakes studied and an analysis of the emission of 20 volatile organic compounds was carried out using a proton transfer reaction mass spectrometer (PTR-MS). Concentrations in emissions from the bottom sediments of VOCs with the following mass–charge ratio (m/z) were analyzed: 57, 61, 63, 69, 75, 81, 83, 85, 87, 95, 97, 99, 101, 109, 111, 127, 129, 137, 149, and 157. The obtained data were analyzed by performing statistical tests and multivariate cluster and PCA analysis. The analysis shows that the lowest concentrations of VOCs were observed from bottom sediments in Lake Jeleń, which is subject to the lowest anthropopressure among the studied lakes. The analysis shows that the lowest concentrations of VOCs were observed from bottom sediments in Lake Jeleń, which is subject to lower anthropopressure among the studied lakes. With the help of cluster analysis, it was possible to collect data on the VOC concentrations into clusters, which resulted in demonstrating similarities between Łazienkowskie and Rychnowskie lakes—lakes connected by an isthmus, and the different characteristics of Lake Jeleń. PCA analysis leads to similar observations. The tested m/z VOCs can be identified using additional analytical methods.

The article describes an X-ray fluorescence method for quantitative analysis of sulfate and total sulfur in bottom sediments of watercourses and reservoirs located in the area of industrial enterprises impact. The quantitative determination of sulfur forms was carried out by analyzing the characteristic curves SKα1,2 and SKβ1,3, as well as the satellite line SKβ′ on X-ray emission spectra measured by an X-ray fluorescence spectrometer with wavelength dispersion. The study shows that these characteristic curves allow not only to determine the predominant form of sulfur, but also to separately conduct quantitative analyses of sulfates and total sulfur after fitting peaks and to separately analyze overlapping spectral lines. The results of quantitative analysis of the chemical state of sulfur by the proposed X-ray fluorescence method were compared with the results of inductively coupled plasma atomic emission spectroscopy and elemental analysis, as well as certified standard samples of soils and sediments. The results are in good agreement with each other.

Based on two years of monitoring of modern bottom sediments of two sections of the Kaliningrad shelf of the Baltic Sea – “Curonian Spit” and “Northern Sambian” – an assessment of the sources of pollution with organotin compounds (OTs) and heavy metals was carried out. The content of individual organotin compounds and OTCs spectra obtained by gas chromatography with mass spectrometry of relatively coarse-grained bottom sediments indicate the presence of organotins in significant quantities – the total OTs content (ΣOTs) is from 0.6 to 8.3 ng/g. However, the content of tributyltin (TBT), the main component of anti-fouling systems for marine vessels and the most dangerous endocrine-disrupting compound among the hazardous substances for marine ecosystems, is at a low level (0-2.3 ng/g) in all studied samples and has not increased over the two-year observation period (biodegradation index 1.7-12.4). At the same time, the presence of abnormally high concentrations of mono-, triphenyl- and tricyclohexyltin in the sediments of the ”Northern Sambian” site (up to 30, 7 and 6.4 ng/g, respectively) indicates an additional source of pollution of coastal waters and shelf sediments (for example, plastic litter and agricultural runoff). The absence of significant shipping in the study areas ensures a consistently low level of pollution with tributyltin and its derivatives (less than 0.3 and 2.3 ng/g of TBT in 2017 and less than 0.1 and 1.3 ng/g in 2018 for the sites “Curonian Spit” and “Northern Sambian”, respectively), which indicates the activity of the processes of TBT transformation and self-cleaning of sandy sediments. However, the identified trends and their predictive accuracy require long-term observation and monitoring of the sediment environment using data on the deep-water part of the shelf, enriched in clay and humus components.

Nature-like technologies are being introduced into many human activities including mining wastewater treatment. This work is based on long-term studies of the Sibay copper-zinc-pyrite deposit development. It is dedicated to assessment of geochemical barriers effectiveness in Cu, Zn, Cd removal from water of the Karagayly River (receiving quarry and dump drainage water). The research is based on the elements’ content and forms in water and bottom sediments, pH values etc. Four types of hydrogeochemical environment (formed due to changes in the water use over the past 20 years) were distinguished using discriminant analysis. The mechanisms of barriers formation and destruction were described. Statistical modeling of the metals’ precipitation was performed by multivariate regression analysis. Cu is adsorbed by recently formed Fe hydroxides, and, to a lesser extent, precipitates with sulfates as water pH increases. Antagonism to Mn hydroxides has been demonstrated, due to different physicochemical conditions for their precipitation. Zn enters solid phase mainly with sulfates, this element also forms its own mineral phases. The second mechanism is adsorption by recently formed Mn hydroxides, which corresponds to the idea of similar conditions for the precipitation of metal hydroxides. Cd behavior reflects conditions intermediate between these of Cu and Zn. Contribution of both mechanisms (related to Fe hydroxides and aqueous sulfates) is equal. Antagonism to Mn is absent. According to the assessment results using of nature-like technologies in situ in watercourses, canals and other water drainage systems is promising. Developed statistical models can be used for needs of experimental studies and artificial geochemical barriers engineering.

Rivers, such as the Dong Nai, Saigon, and Mekong, are subject to urban, industrial, and agricultural pollution, leading to a high risk of heavy metal accumulation in bottom sediments. With the aid of a boat and bucket as tools, a survey was conducted to collect sediment samples from the coastal areas (downstream of Dong Nai, Saigon, Mekong Rivers) and islands (Con Dao, Tho Chu) in the Southern region of Vietnam during April and May 2023. Out of a total of 35 samples collected, preserved according to the guidelines of the Ministry of Natural Resources and Environment, the heavy metal indicators were analyzed by atomic absorption spectroscopy, and the average heavy metal concentrations were in the following order: Zn>Cu>Cd>Pb>As. Compared with the Vietnamese Technical Regulation (QCVN 43:2017/BTNMT) on sediment quality and the sediment quality of the Canadian Environment Ministry, the heavy metal concentrations in the research area have not exceeded the specified standards. However, compared with standards from the USA, the Russian Federation, and other regions in Vietnam, the levels are quite high. Moreover, the Igeo index indicates that the concentration of Pb, As, and Cd at many coastal locations downstream of the rivers is heavily polluted. This evidences that in addition to pollution from upstream sources, the activities of the local population significantly contribute to the accumulation of pollution. The research results provide a scientific basis for limiting pollution sources to ensure sustainable development of the studied areas, which is necessary today.

Pollution of the marine environment with organotin compounds is a serious environmental problem due to their extreme toxicity to a wide range of organisms. A high level of contamination with butytin compounds was detected in the bottom sediments of the Koporye Bay, the Gulf of Finland, the Baltic Sea. The concentration of tributyltin and dibutyltin reached up to 35.7 ng(Sn)/g DW and 9.7 ng(Sn)/g DW, respectively. The butyltin compounds transformed in bottom sediments due to the activity of autochthonous sediment microbiota. The degradation rate of tributyltin and dibutyltin was 0.014 day-1 and 0.022 day-1, their half-life, 49.5 and 31.5 days, respectively. Metagenomic analysis revealed the changes in taxonomic composition and the decrease in species diversity of the bottom sediment microbiomes during the transformation of organotin compounds. During the biodegradation of butyltin compounds in bottom sediments, the abundance of bacteria of the genera Acidithiobacillus, Halothiobacillus, Alicyclobacillus, Sulfurospirillum, Denitrovibrio, as well as of methanogenic archaea of the genus Methanolobus increases, which may indicate their potential participation in the biodegradation of organotin compounds. These results may be used to identify active tributyltin degraders for developing self-purification methods of bottom sediments contaminated with organotin compounds.

Abstract The study covered a small, shallow lake, intensively used for recreation (sailing, tourist services and port infrastructure). This study aimed to determine the spatial differentiation of bottom sediments and the potential for phosphorus release in five zones, differing mainly in the type of recreation, depth, direct catchment management, shoreline management and macrophyte presence. The results were used to propose protective and restoration measures to improve the water quality of the studied lake. The innovation in the study was the detailed analysis of bottom sediments, which can be a significant source of pollution besides the external load from the catchment and tourist pressure, in the planned management of this ecosystem. Examination of the physicochemical properties of the bottom sediments showed a clear variation in both composition and potential for internal phosphorus loading. The sediments from the profundal zone, where the most boating activity was observed, together with the sediments from the shallow zone where the boats dock (mooring zone), had the highest potential to supply phosphorus to the bottom waters. This fact was demonstrated by the highest total phosphorus (TP) concentrations in sediments (up to 1.32 mgPg−1 DW) and the content of the most mobile fractions (up to 33%). The other zones associated with the marina, fuel zone, tributary and canal were not significant sources of phosphorus to the ecosystem. Based on the above results, a restoration method involving the removal of bottom sediments from the bottom zone was proposed, supported, of course, by protective measures in the catchment (maintaining a buffer zone around the lake and limiting the inflow of pollutants with tributary waters). The proposed measures with sustainable tourist pressure should improve water quality and thus contribute to protecting this valuable natural landscape.

The paper presents geochemical study of bottom sediments from the MSU structure located on the large Gydratny Fault in the Central Basin of Lake Baikal at a depth of 1380 m. The first detailed data on the spatial variations in the qualitative and quantitative composition of the pore waters are presented. Pioneering data were obtained on Li, B, and Sr contents in the pore water of the sediments. It has been established that fluids are actively discharged within the MSU structure, and the main pathways of their near-surface migration are confined to the tops of hills of this structure on the downthrown fault block. The fluids are highly mineralized (up to 2900 mg/L), showing the highest mineralization ever found in Lake Baikal sediments. The waters are significantly enriched in Mg, Li, B, and Sr but depleted in K. The waters are thought to be generated by the processes of authigenic formation and illitization of smectite at depths of 1 to 2.5 km in the sedimentary sequence. The maximum values of concentration gradients are recorded in the pore waters of the sediments of the western hill, which may indicate a gradual westward shift of the center of the fluid seepage activity along the fault. [ABSTRACT FROM AUTHOR]

Abstract—The paper presents the results of rock magnetic studies and relative paleointensity determinations from sediments of Lake Shira, Khakassia. Carrier minerals of natural remanent magnetization (NRM) were identified through hysteresis loop parameter measurements, thermomagnetic and X-ray diffraction (XRD) analyses. The sediment age was determined by radiocarbon dating; according to age estimates, the studied sediment sequence covers approximately the past 9100 years. To obtain high-quality relative paleointensity results, the determinations were made on linear segments of the pseudo-Arai‒Nagata diagrams. The quality was assessed by the criteria of the number of points in the calculations of slope, quality criterion (q), NRM fraction destroyed in the paleointensity determination interval, and relative paleointensity determination error (σ). According to the rock magnetic studies and XRD analysis, the magnetic carriers are mainly single-domain (SD) and pseudo-single-domain (PSD) magnetite and hematite. The comparison of the obtained relative paleointensity data with model paleointensities calculated for the Shira coordinates from the various models (CALS10K.1b (Korte et al., 2011), PFM9k.1 (Nilsson et al., 2014), HFM.OL1.AL1, CALS10k.2 ARCH10k.1 (Constable et al., 2016)), with absolute paleointensities and with the collection of results from the studies of sedimentary and igneous rocks and archaeomagnetic objects has shown that these data are in good agreement and share common trends. This provides grounds for applying this approach to paleointensity determination from bottom sediments of modern lakes using the pseudo-Thellier method. [ABSTRACT FROM AUTHOR]

It has been shown that, after the shutdown of the nuclear reactor at the Rosatom Mining and Chemical Combine (MCC) in 2010, anthropogenic radionuclides (60Co, 137Cs, 152Eu, and 241Am) are still detected in the bottom sediments (BS) of the Yenisei River in the MCC-affected area. Data from a comparative analysis of the potential mobility of anthropogenic radionuclides in the Yenisei BS surface and lower layers long after the shutdown of the MCC nuclear reactor are presented for the first time. The mobility of radionuclides was estimated using the well-known procedure of sequential extraction of BS. For 60Co, an increase in potential mobility in the lower layers (which are earlier in time of formation) was shown compared to the upper ones for the first time. The radionuclide 137Cs retains high binding strength to mineral matter of BS (close to 100%) regardless of the time factor. The long-term preservation of the high potential mobility of the radionuclides 241Am and 152Eu in BS, as well as the increase in potential mobility of 60Co over time, for the first time makes it possible to consider these radionuclides as potentially bioavailable in the ecosystem of the Yenisei River. [ABSTRACT FROM AUTHOR]

A study of the microplastic (MP) content in water, sediments, and gills and gastrointestinal tract (GIT) of bream (Abramis brama L., 1758) at the mouth of the Mesha River (right tributary of the Kama River) has been conducted. The content of MPs in water is found at the level of 20.5 ± 22.3 items/m3, in bottom sediments (BSs) 44.7 ± 41.8 items/kg, in fish gills 12.3 ± 8.4 items/individual, and in the GIT 14.5 ± 11.5 items/individual. Fibers dominate in water samples and in the gills and GIT of fish; fragments dominate in the sediments. Correlation analysis has shown the presence of a negative relationship between the content of MPs in the gills, GIT, and biological parameters of the fish. In terms of the frequency of occurrence and content of MPs in the gills and GIT, the contamination of the studied fish is at a high level when compared to literature data, which is due to the feeding behavior of bream. [ABSTRACT FROM AUTHOR]

Research has been conducted on the development of an innovative organomineral fertilizer based on local lake resources as a stimulator of germination and growth of crops, as one of the factors in achieving the goal of environmental sustainability. The results obtained are based on the environmental friendliness of the technology, increasing yields, and obtaining environmentally friendly products. This, in turn, will not only save mineral resources but also make it possible to use the resources from the bottom sediments of local lakes, and their rational extraction will contribute to the sustainable development and restoration of lake ecosystems. This article highlights the results of laboratory and field studies on the use of sapropel extract at the stage of pre-sowing seed treatment obtained by extraction of bottom sediments from lakes in Northern Kazakhstan. Solutions of aqueous alcohol extract of sapropel extract with concentrations of 0.4, 0.8, 1.2, 1.6, 2.0 g/L and table beet seeds (Beta vulgaris L.) of Bordo 237 variety were used as objects of research. Statistical analysis of laboratory experience data, based on the determination of germination energy and seed germination, allowed us to identify the optimal concentration of sapropel working solution for pre–sowing seed treatment—1.6 g/L. The index of germination energy and germination of seeds during pretreatment with sapropel extract of this concentration was 40% and 50%, respectively. This contributed to an increase in germination energy by almost 2 times and in seed germination by more than 40%. Pre-sowing treatment of seeds with sapropel extract at a concentration of 1.6 g/L in a field experiment contributed to the improvement of biometric indicators of beet fruits, such as diameter, length, and weight. The results of the data on fetal weight of the experimental variant compared with the control were 27% higher, and they were 26% and 32% higher compared with other experimental variants. In the experimental group, the highest yield index was also established, which is 2.15 times, or 53%, higher than the control, which emphasizes the effectiveness of pre-sowing seed treatment with the resulting sapropel suspension. A patent of the Republic of Kazakhstan was issued for the method we developed for obtaining a sapropel product for pre-sowing treatment of seeds: "A method for obtaining a sapropel product for pre-sowing treatment of vegetable seeds". The research presented in the article confirms its effectiveness. The use of this product in pre-sowing seed treatment reduces the number of agrotechnological operations and costs, which makes this method more efficient and economically beneficial for the agricultural industry. Thus, the principle of food security will be implemented, contributing to the preservation of sustainable development and having a positive impact on the health of the population. [ABSTRACT FROM AUTHOR]

The contemporary scientific investigations delves into the mechanisms of migration, distribution, and fractionation of rare earth elements and yttrium (REE + Y) in aqueous environments characterized by humid and arid sedimentogenesis. This particular facet has been employed to solve numerous fundamental inquiries pertaining to lithology and paleolimnology. The manner in which REE + Y behave in water bodies within the cryolithozone remains largely unexplored. By evaluating the concentration levels and distribution patterns of REE + Y in the waters and sediments of the lakes situated in the Ukok Plateau and the Ulagan depression, under the prevailing conditions of cryolithogenesis as the primary geochemical process transforming rocks, soils, and sediments, we were able to augment the existing comprehension of nival sedimentation. In all the lakes examined, the content of REE + Y in the water exhibits a similar magnitude as that of small lakes in other landscape zones of the southern Western Siberia, while the content level of REE + Y is greater in the bottom sediments. The concentrations, distribution and fractionation of REE + Y vary from lake to lake and are determined by several factors: the chemical properties of REE + Y in solutions, the intensity of transformation of host rocks and the mineral forms of the REE + Y in the rocks (minerals). The concentrations, distribution and fractionation of REE + Y in bottom sediments vary slightly from lake to lake except for the contents of Eu, Y, La. The content of Eu, Y, La in the bottom sediment of the lake is influenced by a combination of factors, including their concentrations in the water, the redox conditions of diagenesis, and the mineral composition of the bottom sediment, particularly the amount of accessory minerals. [ABSTRACT FROM AUTHOR]

The development of the mountain and submontane areas of the Azerbaijan Republic in the second half of the last century caused active use of the water resources of small mountain rivers. Under present-day conditions, irrigation systems are the main components of the country's water industry ensuring the growth of economic production. The irrigation system parameters are determined by consumers' capabilities and natural factors (climate, topography, geology). In addition, they mainly depend on the water content of the rivers used. When designing and reconstructing irrigation systems, the main costs are allocated for hydraulic structures that provide the necessary volume of water of the required quality. The arrangement of the water intake facility elements in each specific case is inextricably linked with the best practices in operating similar water intake structures in similar hydrological conditions of rivers. Having analyzed the existing experience in operating such structures, we developed a more rational design of a water intake facility for mountain rivers. [ABSTRACT FROM AUTHOR]

The study covered a small, shallow lake, intensively used for recreation (sailing, tourist services and port infrastructure). This study aimed to determine the spatial differentiation of bottom sediments and the potential for phosphorus release in five zones, differing mainly in the type of recreation, depth, direct catchment management, shoreline management and macrophyte presence. The results were used to propose protective and restoration measures to improve the water quality of the studied lake. The innovation in the study was the detailed analysis of bottom sediments, which can be a significant source of pollution besides the external load from the catchment and tourist pressure, in the planned management of this ecosystem. Examination of the physicochemical properties of the bottom sediments showed a clear variation in both composition and potential for internal phosphorus loading. The sediments from the profundal zone, where the most boating activity was observed, together with the sediments from the shallow zone where the boats dock (mooring zone), had the highest potential to supply phosphorus to the bottom waters. This fact was demonstrated by the highest total phosphorus (TP) concentrations in sediments (up to 1.32 mgPg−1 DW) and the content of the most mobile fractions (up to 33%). The other zones associated with the marina, fuel zone, tributary and canal were not significant sources of phosphorus to the ecosystem. Based on the above results, a restoration method involving the removal of bottom sediments from the bottom zone was proposed, supported, of course, by protective measures in the catchment (maintaining a buffer zone around the lake and limiting the inflow of pollutants with tributary waters). The proposed measures with sustainable tourist pressure should improve water quality and thus contribute to protecting this valuable natural landscape. [ABSTRACT FROM AUTHOR]

Based on the results of an analysis of 174 samples of bottom sediments collected at 48 stations in the Chaun Bay during the cruise 60 of the R/V Akademik Oparin (October 2020), it was found that their grain size distribution varies from poorly sorted silty clay to well sorted sand. The results of the study led to conclusion that the main sedimentation mechanisms in Chaun Bay are thermal abrasion, river runoff, and abrasion, as well as ice rafting and aeolian transport. The zoning of grain size types of bottom sediments is related to the bottom topography and consistent with areas affected by riverine runoff, abrasion, and thermal coastal abrasion, as well as with the direction of currents. The high occurrence of coarse clastic matter in sediments is evidence of abrasion of the coastal zone and active ice rafting of large (up to 15 cm) rock fragments. The vertical variability of the grain size parameters of the studied bottom sediments within the upper 20 cm layer reflects gradual Late Holocene intensification of terrigenous (fluvial and thermal abrasion) fluxes with the current effects of climate change in the Arctic. [ABSTRACT FROM AUTHOR]

Degradation of oil hydrocarbons artificially introduced into bottom sediments in a bioelectrochemical system of a membrane-free (silt) type was studied. Passive bioelectrochemical stimulation by means of electrodes connected by an external circuit with a resistance of 1 kΩ, with an average electric current of ~85 µA was found to cause an increase in degradation during two months from 23.0 to 57.9%. Contamination of bottom sediments with oil (1.32 g/kg) slightly decreased the current in the external circuit of the bioelectrochemical system. The relationship was revealed between the degree of oil degradation and predominant utilization of the lighter n-alkanes in the C14H30–C30H62 series, compared with both the original oil and the residual hydrocarbons of the control. An increase in the representation of the alkB alkane monooxygenase genes relative to the 16S rRNA gene in the total DNA isolated from the sediments was induced by the introduction of hexadecane, both in the case of electrochemical stimulation and in the control. The results may be of interest for the development of new methods of bioelectrochemical removal of organic pollutants from anaerobic environments. [ABSTRACT FROM AUTHOR]

The abundance and diversity of filamentous fungi in the bottom sediments of the Arctic Ocean seas (the Greenland, Barents, and Kara seas) were studied. Samples of the surface bottom sediments were collected during the 84th (July–August 2021) and 86th (October–November 2021) cruises of RV Akademik Mstislav Keldysh. The taxonomic affiliation of the isolated fungi was determined using polyphasic taxonomy. The isolated fungi belonged to 16 genera of different classes of ascomycetous, basidiomycetous, and zygomycetous fungi. The effect of cultivation temperature and different NaCl concentrations on fungal growth was determined, as well as the effect of cultivation conditions on the fatty acid profile for the strains capable of growth on media with increased osmotic potential. While fatty acid composition was shown to be affected by changes in environmental conditions, the response to osmotic stress differed among the studied cultures from deep-sea sediments. [ABSTRACT FROM AUTHOR]

The round goby (Neogobius melanostomus) is an invasive species that can be used as a raw material in the food industry and also as a bioindicator of heavy metal pollution in the environment. In this study, Cd, Co, Cr, Mo, Ni, and Pb were determined in water, bottom sediment, muscle, liver, gills, and gonads of round goby from Dąbie Lake, Szczecin Lagoon, and Puck Bay (all in southern Baltic Sea) using atomic absorption spectrometry. Fulton's condition factor, gonadal and hepatosomatic indices (GSI, HSI) were calculated. Based on estimated daily intake (EDI), target hazard quotient (THQ), and carcinogenic risk (CR), we assessed the human health risk related to the consumption of heavy metals in the round goby. The fish had length and weight ranges of 15.0–16.7 cm and 55.3–80.9 g, respectively. Fulton's condition factor ranged from 1.26 to 2.48 and was highest (p < 0.05) for fish from Dąbie Lake. The range of metal concentrations (in μg kg−1) ranged from 2.92 (Cd in muscles of fish from Szczecin Lagoon) to 106.4 (Ni in muscles of fish from Dąbie Lake). The highest concentrations of Cd, Co, Mo, and Pb were found in livers, Ni in muscles and gonads, and Cr in gills. The calculated EDIs were below the reference oral dose (RfD) and maximum for Cd (1.6% RfD) and Pb (15.1% RfD). The hazard quotient was less than 1. In conclusion, the round goby has a higher potential to accumulate metals from water than from bottom sediments. Consumption of its muscle should not pose a health risk (cancer risk can be considered acceptable). Due to Pb accumulation, moderate consumption should be recommended for pregnant women and children. Finally, our results indicate that the round goby (especially its liver) can be used as a bioindicator to monitor metal contamination of aquatic ecosystems. [ABSTRACT FROM AUTHOR]

In the geochemical review based on records from cruises of the International Deep Marine Drilling Project (DSDP, ODP, and IODP phases) and other literature data on the main types of Pleistocene sediments in the Atlantic, tables of average arithmetic chemical composition, mean weighted chemical composition, accumulation rates, and mass accumulation rates of chemical components are presented. These tables can be used for the comparative analysis with sediments of the same or other stratons in different oceanic basins, as well as with paleoceanic sediments on the continents. The terrigenous matrix dominates within the lithogenic matter. Using methods of mathematical statistics, we revealed the main geochemical associations and major factors determining the chemical composition of studied sediments. Masses of oxides of petrogenic elements and several trace elements have been calculated for Pleistocene sediments. Average chemical composition of Pleistocene sediments is proposed for the Atlantic. [ABSTRACT FROM AUTHOR]

Relationship between the environmental stress index (PES) and the mean total explained variance of biotic parameters (MEV, as a measure of the environmental factors influence on macrozoobenthic communities) is determined using the methods of multiple linear stepwise regression analysis and non-linear estimation. The relationship is S-shaped, with the points of beginning and end of linear growth confined to the PES ≈ 15–16 % and 30 %. These levels should be considered as boundary criteria for the status of macrozoobenthic communities. Under favorable environmental conditions, PES does not exceed 15 % (the first critical level), that is close to a «biologically balanced» state of the communities. The PES values in the range of 15–30 % indicate an increased influence of limiting factors, but this influence is not destructive. The PES values > 30 % (the second critical level) indicate extreme deterioration of habitat conditions and transition to a «physically controlled» state of the communities.

The Matrosskaya, a small river on Paramushir Island (northern Kuril Islands), was surveyed in August 2022. The main hydrological and chemical parameters of the river water are presented; the morphological structure of the river bed and the granulometric composition of bottom sediments are characterized. Potential suitability of the river for the spawning of pacific salmon is discussed.

Group and molecular compositions of organic matter from bottom sediments of the northern sector of the Barents Sea were analysed. The sites where bottom sediments contain organic matter of molecular composition similar to that of oil are identified. Thermally mature hydrocarbon compounds detected in extracts from sediment samples indicates ongoing migration from deeply buried strata and fluid discharge processes on seafloor within the studied areas. Molecular compositions of extracts from bottom sediments were compared with and showed geochemical characteristics similar to some series described for the closest onshore to the study areas. That allows an assumption that the source for migrated hydrocarbons identified in studied bottom sediments can be Mid-Triassic organic-rich claystone intervals which are a part of sedimentary succession of the North Barents deep depression.

The upper layer of bottom sediments in the northeastern Kara Sea is studied. It is shown that the sediment composition is dominated by silt, while the percentage of sand increases towards the coast. The organic carbon content (average value 1.1 wt %) is close to the average content in Kara Sea sediments, increasing at deep-sea stations. The linear correlation found between the organic carbon content and surface area of sediments shows adsorption on particle surfaces and is the predominant form of organic matter (OM) accumulation in the sediments. The average n-alkane concentration in the analyzed samples is 1.1 μg/g of sediment; the distribution spectrum is dominated by odd high-molecular homologues of terrigenous origin. [ABSTRACT FROM AUTHOR]

The sources of supply and transformation of organic matter (OM) as it transitions from dissolved form to particulate matter, fluffy layer, and bottom sediments were investigated along a meridional transect from the Lena River delta to the continental slope (in the depth range of 10 to 2390 meters, cruise 63 of the R/V Akademik Mstislav Keldysh, September 2015). The study of OM molecular markers showed that dissolved and particulate organic matter of marine and terrigenous origin biodegrades in the water column and accumulates insignificantly in bottom sediments. Thus, OM from Lena River runoff does not contribute to the formation of OM in bottom sediments in summer. An area of influence of under-ice blooms on the sedimentation process was identified on the outer shelf. [ABSTRACT FROM AUTHOR]

Investigations into the microbial community of bottom sediments in the karst Lake Black Kichier were conducted. These sediments exhibited elevated levels of sulfide, dissolved methane, and organic matter. Direct radiotracer experiments revealed substantial rates of microbial processes involved in the decomposition of organic matter. Uncultivated archaea belonging to the phylum Thermoplasmatota were identified within the microbial community. Metagenomic analysis unveiled representatives from five orders: Methanomassiliicoccales, Thermoprofundales (formerly known as Marine Benthic Group D and DHVEG-1), DTX01, SG8-5, and Candidatus Gimiplasmatales (formerly UBA10834). These archaea were previously believed to occur exclusively in deep marine sediments characterized by extreme organic matter scarcity. This discovery reshapes our understanding of the role played by Thermoplasmatota archaea, spanning five orders, in the degradation segment of the carbon cycle. [ABSTRACT FROM AUTHOR]

Gases from bottom sediments of the Laptev–Siberian Sea zone contain methane (up to 8.3047 cm3/kg) and its homologues (up to pentane including) totaling 0.0259 cm3/kg. The established values of the carbon isotope composition of methane (δ13С), the molecular weight of the hydrocarbon fraction, the weight concentrations of С1–С5 hydrocarbons and their ratios, the "wetness" and "transformation" coefficients of the hydrocarbons fraction indicate the presence of various syngenetic and epigenetic gases in different source rocks: bottom sediments, peatlands, coal, gas, and gas hydrate? deposits, solid bitumen, igneous rocks, and inferred oil and gas reservoirs. It has been established that the vertical and lateral distribution of hydrocarbon gases in sediments depends on the influence of a complex of geological factors: fold and fault tectonics, magmatism and seismic activity in the region, coal, oil and gas potential and bitumen content, organic saturation and lithological composition, hydrogeological, geocryological, and other conditions for accumulation of gases or their degassing. [ABSTRACT FROM AUTHOR]

Sedimentary material sampled in the southwestern Kara Sea both directly in ice scours and on background surfaces undisturbed by ice scouring has been studied. Based on studies of the physical properties and lithomineralogical features of bottom sediments in the ice scours, the boundary of ice scouring impact (exaration contact) was identified. Based on the X-ray diffraction analysis of <0.001-mm fraction, the chlorite structure is sensitive to temperature in samples taken below this contact, in contrast to the overlying samples. Together with the results of microscopic studies of thin sections, this fact indicates the neoformation of chlorite. The presence of secondary chlorite in near-surface conditions can suggest the glaciodynamic impact (pressure) of iceberg keels on bottom sediments. Microstructures of the ice scour sediments differ both in different test sites of the study area and within the same scour, depending on the location of sampling point on the transverse profile of morphosculpture. [ABSTRACT FROM AUTHOR]

The study investigated the sorption behaviour of 99Tc and 125I on bottom sediments from the Japan Sea, Khanka Lake and commercially available sapropel. It was determined that organic matter can have an impact on the iodine sorption process. After a 20-day period, sapropel reached an equilibrium state with a sorption value of up to 100%. In real systems of bottom sediment–water in the Far East region, iodine sorption was found to be superior on marine bottom sediments with a sorption value reaching 85% within 20 days, as opposed to freshwater sediments which only reached up to 35% within the same period. Tc(VII) in the form of pertechnetate anion exhibits no sorption under either aerobic or anaerobic conditions in the pH range of 4–11. Under aerobic conditions at pH 11 Tc(IV) is sorbed up to 15% only on sapropel; under anaerobic conditions at pH 7 the sorption reaches 25% for lake sediments, 10% for marine sediments and when the pH is 11, the sorption value of Tc by sapropel is as high as 100%. [ABSTRACT FROM AUTHOR]

Due to their toxicity, lack of bioaccumulation and biodegradability, and ease of binding to sediments, heavy metals are considered the main pollutants of rivers. It is, therefore, necessary to control and monitor these pollutants. The present study analyzed the Krzna River, which flows in southeastern Poland and has an outlet to the Bug River. Over much of its length, the Bug River forms Poland's border with Belarus, while its origin is in Ukraine. The main purpose of the conducted research was a qualitative and quantitative analysis of selected heavy metals, i.e., Ni, Pb, Zn, Cd, and Cu, in bottom sediments and surface waters of the Krzna River. The secondary objectives were to evaluate the level of contamination of the studied matrices and identify the sources of pollution. Eighty samples of water and bottom sediments from the Krzna River were collected for the analysis. Due to the varying distribution of metals under the influence of changes in temperature, precipitation, and humidity, the samples were collected in May and August 2023. The average cadmium content in the sediments studied was the same in both May and August, at 0.6 mg/kg. In contrast, the nickel content of the sediments ranged from 4.6 to 6.1 mg/kg in May and from 4.8 to 6.8 in August. Only nickel and cadmium of the five heavy metals tested were present in amounts exceeding the geochemical background value. Analysis of the results indicates that only a minimal amount of heavy metals remain dissolved in the surface waters, and the remainder contaminates the sediments. The average concentrations of metals in the studied bottom sediments and surface waters were as follows: zinc > lead > nickel > copper > cadmium. The content of metals in the studied sediments was not high, but at the same time, their presence above the geochemical background indicates anthropogenic human activity. Any changes in hydrodynamic conditions and various environmental factors may result in the re-release of heavy metals contained in sediments into surface waters. [ABSTRACT FROM AUTHOR]

Shallow lake sediments have huge potential for carbon storage, but they are vulnerable to various environmental changes and are highly susceptible to becoming a source of carbon emissions. Understanding the amount of sediment carbon storage can provide information about the potential of shallow lakes in mitigating climate change. In this study, sediment sampling was conducted at 12 study sites in Chaohu Lake, China, and sediment water content, grain size, bulk density, and sediments organic carbon (SOC) content were examined in five layers along the vertical direction, respectively, and the distribution and storage of SOC were estimated. The results showed that the surface sediments in the west lake area of Chaohu Lake would release 66,300 t of SOC to the overlying water body in the future. The sediments in the middle lake area and the east lake area will absorb another 15,900 t and 17,300 t of TOC from the water body in the future, respectively. Overall, the lake-wide sediments will release 33,100 t of SOC into the water body in the future. In addition, the results of the study also indicate that human activities are another major influence on the change in organic carbon stocks in lake sediments, and therefore, proactive measures for the restoration and protection of lake sediments are essential because increasing the SOC stocks in the sediments and maintaining the lakes in a sustainable manner can contribute to the crucial role they play in mitigating climate change. [ABSTRACT FROM AUTHOR]

The study analyzes polycyclic aromatic hydrocarbons (PAHs) isolated from bottom sediments of the Barents and Norwegian seas (2019–2021 cruises of the R/V Akademik Mstislav Keldysh). Elevated PAH concentrations (up to 16 900 ng/g) are recorded in the coastal region of the Svalbard archipelago, and low ones, in the Greenland Basin and the eponymous ridge (up to 80 ng/g), as well as on the continental slope of the Barents Sea (up to 240 ng/g on average). Among cata-condensed PAHs, 2–3 ring polyarenes are the most common: naphthalene, 1- and 2-methylnaphthalenes, and phenanthrene, while among peri-condensed PAHs, 4–6 ring polyarenes are the most typical: fluoranthene, pyrene, and benz(a)anthracene. Anthropogenic sources in the bottom sediments of the study area are of subordinate importance compared to their natural input from the sedimentary stratum with fluid fluxes and erosion. [ABSTRACT FROM AUTHOR]