Upper Layer Of Bottom Sediments Research Articles

Метано- и сульфидогенез в озерах полуострова Абрау (Краснодарский край)

The geographical position, tectonic and geological-hydrogeological structure of the basin of the Malyy Liman and Abrau lakes, their landscape features as natural monuments of regional importance located on the territory of the Abrau peninsula of the Krasnodar Territory are described. Using the example of the aquatic landscapes of the Malyy Liman and Abrau lakes and the river of the same name, water and bottom sediments were studied. Hydrochemical parameters, the content of methane and sulfide sulfur in bottom sediments and methane in water as components of aquatic landscapes were studied. The results of the determination of sulfides, as well as the characteristic odor and color of bottom sediments, indicate the presence of free H2S and hydrotroilite (FeS ∙ nH2O) in them. Electron microscopy revealed the presence of hollow spheres in the bottom sediments, which indicates their possible gas saturation. Microinclusions of biogenic pyrite (FeS2), which was formed on fragments of plant and organism residues, were found under an electron microscope. In aerobic-anaerobic conditions of the upper layer of bottom sediments of lakes, pyrite formation occurs both directly through a one-stage process of pyritization of reactive iron, but also through a multi-stage process of pyrite formation from iron monosulfide. It has been established that lakes are exposed to anthropogenic influences, which can increase many times during the holiday season. This leads to their eutrophication and increased meanogenesis, which in turn contributes to the activation of methane emissions into the atmosphere. Specific methane fluxes from the water surface of the Malyy Liman and Abrau lakes have been determined.

Hydrocarbons in waters and bottom sediments of the coastal areas of the Caucasian sector of the Black Sea (2021–2023)

The current level of aliphatic and polycyclic aromatic hydrocarbons was determined in suspended particulate matter of waters (mainly in surface waters) and in upper layer of bottom sediments of coastal areas in the Caucasian sector of the Black Sea of the Russian Federation (September 2021, May and September 2022, March 2023). IR method was used to determine the aliphatic hydrocarbons, and the method of high performance liquid chromatography was employed for PAHs. The average concentration of aliphatic hydrocarbons was ≈20 μg/L and for polycyclic aromatic hydrocarbons ≈130 ng/L in suspended particulate matter in open surface waters of Gelendzhik and Golubaya bays. Their content naturally increased as they approached the coast. Despite the decrease in hydrocarbon concentrations in surface waters in recent years, the Kerch Strait and Novorossiysk remain the most polluted areas as before. Higher concentrations in the waters of the Taman Peninsula may be caused by the seepage of hydrocarbons from the sedimentary layer. Hydrocarbons are accumulated in bottom sediments, that leads to their rising portion in total organic carbon (e.g., aliphatic hydrocarbons up to 14.2 % in the Tuapse region and 13.1 % in the Novorossiysk region). Along with contamination from anthropogenic sources, natural processes also affect the hydrocarbon levels such as high biological productivity of the area and fluid flows from the sediment layer.

Grain Size Distribution, Organic Carbon and Geochemical Markers in the Surface Layer of Bottom Sediments in the Northeastern Part of the Kara Sea

The upper layer of bottom sediments in the northeastern part of the Kara Sea is studied. It is shown that the composition of sediments is dominated by silt, the proportion of sand increases towards the shore. The content of organic carbon (average value — 1.1% wt.) is close to the average content in sediments of the Kara Sea, increasing at deep-sea stations. The revealed linear relationship between the content of organic carbon and the surface area of sediment shows that sorption on the particles surface is the predominant accumulation form of organic matter (OM) in sediments. The average n-alkanes concentration in the analysed samples is 1.1 μg/g of sediment, the distribution spectrum is dominated by terrigenous origin odd high-molecular homologues.

Hydrocarbons in bottom sediments of coastal waters of the Kazantip peninsula (Azov Sea)

The aim of the article is to study the bottom sediments of the coastal zone of Kazantip peninsula in the Sea of Azov of complexes of hydrocarbon pollution. This water area is a site with a high level of recreational load, despite the presence of a nature reserve there, and is also characterized by a rugged coastline, which causes the accumulation of pollution in bottom sediments. The material for the study was samples of the upper layer of bottom sediments, which were taken in the summer of 2021 in the coastal waters of Cape Kazantip (Sea of Azov) with a manual sampler from depths of up to 1.5 m both within the protected area and beyond its borders. Determination of hydrocarbons in bottom sediments was carried out by gas and liquid chromatography in accordance with certified methods. The paper presents new original materials on the distribution of hydrocarbons in bottom sediments in the area of Kazantip peninsula, as well as an assessment of the local level of pollution of marine soils in this area. The ratio of hydrocarbons of different origin in bottom sediments is given. In addition, possible ways and sources of pollution are indicated. As a result of the study, it was shown that the bottom sediments of the coastal zone of Kazantip peninsula are not polluted and the concentrations of the main groups of hydrocarbons are within the range of average values for the Sea of Azov. But, despite this, there are traces of fresh inflows of petroleum hydrocarbons, which can be of both anthropogenic and natural origin.

The First Data on the Mineralogy and Geochemistry of the Suspension of Lake Onego

Abstract —This paper presents the first data on the mineralogy, geochemistry, and quantitative distribution of suspension determined with the use of sedimentation traps installed in Lake Onego (the exposure time was one year (2019)). The obtained data on the mineralogic and geochemical composition of the recent suspension of the Onego water column are compared with the data for the surface layer of the lake bottom sediments (0–10 cm). Data on the sedimentation rates for the substance determined with the sedimentation traps have been obtained for the first time for Lake Onego. The estimates of the sedimentation rates differ slightly from the results of calculation of the sedimentation rates by radioisotope dating based on the distribution of 210Pb activity in the upper layer of bottom sediments in combination with the data on 137Cs. It has been established that the mineral part of the dispersed sedimentary matter that entered the lake reaches the bottom sediment without significant changes. The geochemistry of the sedimentation traps is similar in many respects to the geochemistry of the upper part of the bottom sediments (0–10 cm) in different areas of Lake Onego. The dispersed sedimentary material and the bottom sediment differ in the amount of the biogenic part (in the bottom sediment layer (0–10 cm), the biogenic part loses a significant part of organic matter). The bottom sediments are characterized by a strong predominance of the ferruginous varieties of illite and chlorite, in contrast to the suspension with the prevailing Mg–Fe varieties of these minerals. Degraded mica minerals brought by rivers are regenerated to normal ferruginous illites and chlorites directly in the uppermost part of the bottom sediments. The bottom sediments are characterized by higher manganese and molybdenum contents, and the material from the sedimentation traps, by high mercury contents.

Redox conditions of bottom sediments and macrozoobenthos characteristics in the Kruglaya and Kazachya bays (Sevastopol)

A lack of systemic and environmentally efficient approach to exploitation of the Kruglaya and Kazachya bays (Sevastopol) resulted in their severe pollution. The conjunction of natural and anthropogenic factors led to deterioration of habitat conditions of benthic communities. The aim of this work was to carry out complex research of Kruglaya and Kazachya bays’ ecosystems to study peculiarities of formation of redox conditions in bottom sediments and bottom water layer, as well as their effect on macrozoobenthos characteristics. Bottom sediments were sampled by diver in plexiglass tubes hermetically sealed at the top and bottom; it helped in preserving a fine structure of bottom sediments and bottom water layer. To study benthic communities, samples were taken in the same spot with a manual sampler. To obtain chemical composition of pore waters with high vertical resolution, the voltammetry analysis was carried out. Calculation of an oxygen flux at the boundary and in the upper layer of bottom sediments was performed according to the vertical profile of oxygen concentration in pore waters and geochemical analysis with applying the equation for the Fick’s first law and considering concentration gradient and molecular diffusion of oxygen in pore waters. Standard hydrobiological methods were applied for the analysis of benthic material. When calculating the values of the Shannon diversity index (H’), the binary logarithm was used. The data analysis showed as follows: a high level of anthropogenic load and restricted water dynamics resulted in siltation of bottom sediments in the studied water areas, which obstructed oxygen penetration; the accumulation of organic carbon contributed to its active consumption. Stratification of a water column due to limited water exchange, high temperature of bottom water, accompanied by a decrease in oxygen solubility, and finely dispersed nature of bottom sediments contributed to the fact that the rate of oxygen input was lower than the rate of oxygen consumption for organic matter oxidation. This was followed by the development of oxygen deficiency zones and emergence of reduced compounds, in particular hydrogen sulfide. Importantly, suboxic conditions prevailed in the upper sediment layer, and anaerobic conditions prevailed below. Due to this, the main forms of macrozoobenthos were species tolerant to oxygen deficiency and organic pollution. Specifically, in some spots of the Kazachya Bay, polychaetes alone were recorded. At the same time, in the Kruglaya Bay mouth area, intense water dynamics and morphological peculiarities of bottom sediments contribute to saturation of the upper sediment layer with oxygen. Based on oxygen concentration data for the surface (0–5 mm) sediment layer (pore waters) and on geochemical peculiarities of bottom sediments (moisture and porosity), the oxygen flux at st. 4 (the Solenaya Bay) was calculated; the value was 0.73 M·m−2·year−1. Considering oxygen concentration in bottom water layer (259 μM), the time for complete depletion of oxygen or its renewal is about 5 months if taking into account biogeochemical processes alone. Hence, it can be assumed that the ecosystems of the Kruglaya and Kazachya bays are in the stage of degradation. Their further exploitation without a developed systemic and rational approach will result in a critical deterioration of the ecosystems – the emergence and spread of environmental risk zones. It will reduce the recreational and socioeconomic attractiveness of these areas.

LITHOLOGY AND HYDRODYNAMICS OF THE BLACK SEA ODESSA COAST UNDERWATER PART

Problem Statement and Purpose. The results of lithological studies, including granulometric analysis, are needed to identify the conditions of sedimentation and distribution of rock fragments by size. They are an indicator of the sedimentation processes dynamic structure peculiarities. The study of the sediment regime is important for the development of measures related to the protection of shores from erosion. The aim of the work is to identify the lithological features of the bottom sediment types distribution on the protected section of the Odessa coast near Cape Maly Fontan. Data & Methods. The materials for this work were obtained in the field research in the summer 2019 in the coastal zone between the hydrobiological station of Odessa I. I. Mechnikov National University, and Cape Malyj Fountain. Three measuring profiles were made perpendicular to the shoreline at 1200 m towards the sea to a depth of 18 m. 35 samples were taken from the upper layer of bottom sediments. Field samples processing was performed in the Problem Research Laboratory of Engineering Geology of the Sea Coast, Reservoirs and Mountain Slopes of Odessa I. I. Mechnikov National University. Granulometric classification was performed. Excel, Statistica, Golden Software Surfer programs were used to process the results. Results. Underwater relief analysis showed that the coastal part is an abrasive terrace, on which ancient landslides relics are widespread. There are 7 main lithological types of bottom sediments detected. The largest areas covered by fine-grained loamy sands and shell detritus with gravel, pebbles and sand. Analysis of distribution curves and cumulative curves of granulometric distribution showed that coarse sediments are characterized by multi-vertex distribution curves and stepwise stretched cumulative curves, which indicates the heterogeneity of sediments in granulometric distribution. For fine-grained material, which is well sorted, the distribution curves are almost single-vertex, and the cumulative curves have a large steepness and a simple, non-stepped shape. There are three hydrodynamic detected in bottom sediments lithology according on statistical parameters of grain size. Outer marine part with depth more than 15 meters characterized by low hydrodynamic processes and presented by good-sorted sands and silt. The central part of polygon in 4–15 meters depth covered by shell detritus with gravel and pebble of carbonate rocks and connected with rocky extrusions after coastal landslides. The feature of this part is active hydrodynamic processes. The rocky extrusions presented like natural breakwater and due to waves braking and collection of different types of sediments. The coastal part in 2–4 m depth in front of constructed breakwater leads to decreasing of wave energy and sedimentation of good-sorted sands.

Behaviour and distribution of heavy metals at the boundary of “water-bottom sediments” in mouth zones of rivers

The aquatic elementary landscapes of the Don and Northern Dvina Rivers mouth zones as arenas of mass transfer of heavy metals (HM) are studied. The results of long-term comprehensive studies of the authors, which included sampling of water and the upper layer of bottom sediments in order to determine the content of mercury, copper, methane, hydrogen sulfide, as well as pH and Eh values, are presented. According to the type of prevailing geochemical conditions and the level of anthropogenic impact, natural, man-made and natural-anthropogenic aquatic elementary landscapes are distinguished. The bottom water layers in both rivers were characterized by positive Eh values, but it should be noted that they were generally relatively low for surface watercourses. According to the values of the redox potential and the hydrogen index, the methane content and the total hydrogen sulfide, the presence of the following conditions is proved – oxygen, gley, hydrogen sulfide, oxygen-gley and gley-hydrogen sulfide. At the water - sediment interface, in most cases, there was a decrease in pH values by the first tenths of the values, while Eh usually decreased quite sharply, often to negative values. In terms of methane content, the bottom sediments of the aquatic elementary landscapes of the Don and Northern Dvina rivers were similar, while the concentration of total hydrogen sulfide was higher in the Don. It is shown that in the mouth zone of the Don and Northern Dvina rivers, in areas subject to constant organic pollution and eutrophication, there is an increase in the total content of mercury and copper in the bottom sediments. Higher concentrations of gross mercury will generally be found in natural and anthropogenic landscapes dominated by hydrogen sulfide and gley-hydrogen sulfide environments. The important role of microparticles of the polydisperse medium of bottom sediments in the deposition of copper and mercury is revealed.

ИЗМЕНЕНИЕ ТЕПЛОПОТОКА НА ГРАНИЦЕ ВОДА– ДОННЫЕ ОТЛОЖЕНИЯ В МАЛОМ ОЗЕРЕ В ТЕЧЕНИЕ ГОДА

The features of the variability of the heat flux at the boundary of the water column with bottom sediments in the central part of the small polymictic Lake Vendyurskoe (southern Karelia) were analyzed according to the data of year-round temperature measurements from November 2018 to October 2019. It was shown that the heat flux directed from the bottom sediments into the water reached 6–8 W/m2 in the pre-ice period and at the moments of ice formation and breaking, and did not exceed 1 W/m2 during most of the winter. A week after the ice-off (May 3–4, 2019) the water column was completely mixed, the heat flux changed its sign, and heat accumulation in the upper layer of bottom sediments began. The heat flux directed to bottom sediments was 4–6 W/m2, periodically increasing to 8-12 W/m2 from mid-May to late July and from the second decade of August to the first decade of September. Against the background of a prolonged cooling during the first ten days of August, the heat flux changed sign with daily frequency, the amplitude of daily fluctuations reached ± 2.5 W/m2. Autumn cooling of the Lake Vendyurskoe began in early September 2019, the heat flux sign changed on September 14–16, 2019.

Comparative Analysis of Chlorophyll a Content in Freshwater and Marine Waterbodies

The data on chlorophyll content in the water and bottom sediments in freshwater Rybinsk Reservoir (Upper Volga) and Aniva Sea Bay (Sea of Okhotsk) are summarized. The average concentration of chlorophyll a in plankton of the reservoir is 23.0 ± 1.9 μg/L, in the bay 0.77 ± 0.06 μg/L, in the bottom sediments 144.2 ± 14.9, and 8.2 ± 0.7 μg/g in the dry sediment, respectively. Correlations between pigment concentrations in the euphotic zone, in the aphotic bottom layer, the whole column of water, and the upper layer of bottom sediments, as well as the relationship of pigments with depth (within 6–100 m) and transparency (from 1 to 18 m), were revealed. It is shown that the general relations for two waterbodies are approximated by nonlinear equations with determination coefficient values (R2) from 0.37 to 0.93. The patterns of the relationship between pigment indices are similar in both waterbodies.

Natural radionuclides in bottom sediments of the saline lakes. What factors determine their concentration?

Concentrations of 226Ra, 40K, 210Pb, 234Th, 238U, 232Th, and 210Po were determined in bottom sediments of 11 Crimean saline lakes. From lake to lake, concentration of all radioisotopes and their total amount varied. The greatest variability was noted for 226Ra (CV = 1.268), and the smallest for total sum of radionuclides (CV = 0.336). In all lakes, the concentration of studied radionuclides did not exceed the maximum concentrations found in bottom sediments of water bodies in different regions excepting Lake Sasyk-Sivash where 226Ra concentration was slightly higher than previously found the upper limit. There are the inter-lake differences and temporal changes in radionuclide concentrations in the bottom sediments. Salinity is not main determinant of radioisotope concentrations in the lake bottom sediments, but may modify their concentrations in some ranges. The behavior of 210Pb and 210Po under anoxic conditions differs from observed in oxic. Authors conclude that there is no any single factor itself controlling concentrations of radionuclides in the upper layer of bottom sediments in the saline lakes; there is multicausal determination. Only coupling of many factors (physical, chemical, and geochemical properties of radioisotopes, and geological, climatic, and biological) determines radionuclide distribution patterns.

Heavy metals in the bottom sediments of the Tendrivska bay

The article describes several research results of geoecological direction, which included field sampling of bottom sediments, soils, coastal sediments at different sites within the territory of the Black Sea Biosphere Reserve NAS of Ukraine, in particular, the Tendrivska and Yahorlitska bays. The complex of the laboratory works included determination of chemical, microelement, particle size distribution composition of samples and study of their material characteristics on a scanning electron microscope. The study of the ecological state of the Reserve’s bottom sediments, as well as comparison of pollutant content in sediments of various parts of the protected water area was based, in particular, on determining the concentrations a few heavy metals (copper, nickel, zinc, lead, tin). The choice of research objects was determined by the peculiarities of the organization of agricultural activities within the arable lands bordering the boundaries of this reserve. The results obtained showed a significant impact of the geomorphological structure of the area and hydrodynamic characteristics of certain areas of the water area within it on the distribution of the material component of bottom sediments. The mineral and particle-size composition of bottom sediments should be considered the main factor in the uneven distribution of microelement concentrations, which in turn is determined by the location of zones of coastal erosion and sediment accumulation. Insignificant relative excesses of the copper content in the surface layer of the bottom sediments of the water area, fixed in the northern part of the Tendrivska Bay, can be connected with the discharge of fresh water from the network of canals, which is part of the agro complexes for rice cultivation, as well as “tailings” of water from the water supply systems of the Krasnoznam’yanska irrigation system. Studies have also shown that the content of most heavy metals in the upper layer of bottom sediments in the Black Sea Biosphere Reserve is lower than the average figures for modern Black Sea bottom sediments presented in literature sources.

Influence of temperature variability in the near-bottom layer on the results of geothermal measurements in the Kvitøya trough (Barents sea)

According to a study of the water column thermal variability in the Kvitøya trough (the northern part of the Barents Sea) substantial water temperature fluctuations in the near-bottom layer were found, both the seasonal and interannual, which affect the distribution of temperature in the upper layer of bottom sediments, and therefore the results of geothermal measurements. The contribution of temperature fluctuations on the water-sediments boundary to the values of the conductive heat flow measured during 25th cruise of the RV “Akademik Nikolaj Strakhov” was calculated. Endogenous heat flow was determined.

Influence of Temperature Variability in the Near-Bottom Layer on the Results of Geothermal Measurements in the Kvitøya Trough (Barents Sea)

According to a study of the thermal variability of the water column in the Kvitoya trough (northern part of the Barents Sea), substantial water temperature fluctuations in the near-bottom layer were found, both seasonal and interannual, which affect the temperature distribution in the upper layer of bottom sediments and, therefore, the results of geothermal measurements. The contribution of temperature fluctuations at the water–sediment boundary to the values of conductive heat flow measured during cruise 25 of the R/V Akademik Nikolaj Strakhov was calculated. Endogenous heat flow was determined.

Formation of methane concentration and electromagnetic-field anomalies in southwestern Peter the Great Gulf (Sea of Japan)

We report methane concentrations in the bottom water layer and the upper layer of bottom sediments and the results of acoustic explorations of methane seeps on the shelf bordering the continental slope of the Sea of Japan region, in which electromagnetic Schumann’s resonance oscillations were earlier recorded at continental-slope water depths of 500, 1000, and 2000 m. The occurrence of Schumann’s resonances at such great depths is explained by an increase (a factor of more than 25) in the electrical resistivity of a ~2000 m thick sediment layer with the pore space largely filled with free methane. A new method is proposed for determining the depth of the sources of anomalous concentrations of methane in bottom sediments or in the bottom water layer on a deep shelf. The method is based on recording Schumann’s resonances during measurements of the natural electric field at a series of increasing depths in areas bordering the continental slope.

Radionuclides and mercury in the salt lakes of the Crimea

90Sr concentrations, resulting from the Chernobyl NPP accident, were determined in the salt lakes of the Crimea (Lakes Kiyatskoe, Kirleutskoe, Kizil-Yar, Bakalskoe and Donuzlav), together with the redistribution between the components of the ecosystems. The content of mercury in the waters of the studied reservoirs was also established. Vertical distributions of natural radionuclide activities (238U, 232Th, 226Ra, 210Pb, 40K) and anthropogenic 137Cs concentrations (as radiotracers) were determined in the bottom sediments of the Koyashskoe salt lake (located in the south-eastern Crimea) to evaluate the longterm dynamics and biogeochemical processes. Radiochemical and chemical analysis was undertaken and radiotracer and statistical methods were applied to the analytical data. The highest concentrations of 90Sr in the water of Lake Kiyatskoe (350.5 and 98.0 Bq/m3) and Lake Kirleutskoe (121.3 Bq/m3) were due to the discharge of the Dnieper water from the North-Crimean Canal. The high content of mercury in Lake Kiyatskoe (363.2 ng/L) and in seawater near Lake Kizil-Yar (364 ng/L) exceeded the maximum permissible concentration (3.5 times the maximum). Natural radionuclides provide the main contribution to the total radioactivity (artificial and natural combined) in the bottom sediments of Lake Koyashskoe. The significant concentration of 210Pb in the upper layer of bottom sediments of the lake indicates an active inflow of its parent radionuclide—gaseous 222Rn from the lower layers of the bottom sediment. The average sedimentation rates in Lake Koyashskoe, determined using 210Pb and 137Cs data, were 0.117 and 0.109 cm per year, respectively.

Organic carbon in water, particulate matter, and upper layer of bottom sediments of the central part of the Kara Sea

Based on data obtained in the course of the 59th cruise of RV Akademik Mstislav Keldysh, the content of organic carbon was determined in water (dissolved organic carbon, DOC), particulate matter (particulate organic carbon, POC), and bottom sediments of the Yenisei estuary and of the central part of the Kara Sea during the summer–autumn season of 2011. The decisive impact of the waters of riverine runoff upon the variability of DOC and POC concentrations in the marine aquatic area is shown. POC enrichment in the autochthonous component is revealed for the frontal zones, as well as the increase of DOC concentrations in the area of the northern extremity of the Novaya Zemlya Islands. The distribution map of organic carbon (Corg) in the upper layer of bottom sediments of the central part of the Kara Sea is plotted on the basis of the analysis of the authors' and published data. A pronounced enrichment of the thin upper layer (0–0.5 cm) of bottom sediments in organic carbon (>20%) is registered at most of the stations and depends neither on lithological composition of sediments nor on the location of sampling sites.

Spatial and seasonal variability of pore water phosphorus concentration in shallow Lake Swarzędzkie, Poland

Pore waters play an important role in phosphorus dynamics in aquatic ecosystems. Phosphorus concentrations in pore waters are much higher than above the bottom. This is confirmed by the results of this study concerning the hypereutrophic lake. Pore water was analyzed at 11 sampling stations in the upper layer of bottom sediments. This water was separated by centrifugation and phosphorus level was measured spectrophotometrically with ascorbic acid as a reducer. Total phosphorus concentration in pore waters ranged from 0.5 to 8.1 mgP l(-1) (mean 3.2 mgP l(-1)). Mean phosphorus concentration in pore water samples of this lake was the highest in summer and the lowest in winter. High concentrations were observed in samples from the pelagial and low from the macrophyte zone.

Methane formation and oxidation in the meromictic oligotrophic Lake Gek-Gel (Azerbaijan)

The production and oxidation of methane and diversity of culturable aerobic methanotrophic bacteria in the water column and upper sediments of the meromictic oligotrophic Lake Gek-Gel (Azerbaijan) were studied by radioisotope, molecular, and microbiological techniques. The rate of methane oxidation was low in the aerobic mixolimnion, increased in the chemocline, and peaked at the depth where oxygen was detected in the water column. Aerobic methanotrophic bacteria of type II belonging to the genus Methylocystis were identified in enrichment cultures obtained from the chemocline. Methane oxidation in the anaerobic water of the monimolimnion was much more intense than in the aerobic zone. However, below 29–30 m methane concentration increased and reached 68 μM at the bottom. The highest rate of methane oxidation under anaerobic conditions was revealed in the upper layer of bottom sediments. The rate of methane oxidation significantly exceeding that of methane production suggests a deep source of methane in this lake.

Contaminated sediments as a potential source of Zn, Pb, and Cd for a river system in the historical metalliferous ore mining and smelting industry area of South Poland

Background, aim, and scope Elevated levels of heavy metals in the aquatic and soil systems can be caused by the weathering of mineralized rocks. This enrichment is often considerably enlarged by historical and current mining and smelting activities. In Poland, the most contaminated river systems are those in the Silesia region. The metalliferous ore mining and smelting industries have been the main sources of heavy metal pollutions over the last 100–170 years. The previous and present studies have shown very high concentrations of heavy metals in the bottom sediments of the Mala Panew River, the most polluted tributary of the Oder River. The main objective of this work was to study temporary changes of selected metal (Zn, Pb, and Cd) concentrations in upper layer of bottom sediments at the measuring point near the outlet of the Mala Panew River into the Oder River, and to determine the vertical distribution of the metals in the sediment cores from the most polluted middle part of this river. The mobility of the metals and their potential bioavailability were assessed based on metal partitioning in the sediments and metal concentrations in pore waters. The presented data were compared with metal concentrations in aquatic sediments from similar historical mining and smelting sites in Poland and other countries.