Bottom Sediment Samples Research Articles

Content of heavy metals in bottom sediments of drained Kakhovka Reservoir

The article highlights the ecological danger of the destruction of the Kakhovka HPP dam and the draining of the Kakhovka Reservoir. The results of experimental studies of the content of mobile compounds and gross forms of heavy metals in five samples of bottom sediments taken from the bottom of drained reservoirs taken on the territory of the Kushugum community of the Zaporizhia district of the Zaporizhia region. Two samples were taken from the bottom of the former flood zone (Balabyne village), 2 samples — from the bottom of the former limestone quarry, which was connected to the floodplain of the Dnipro (Kushugum village) and 1 sample taken from the open area of the Kakhovka Reservoir (Malokaterynivka village). Based on the results of the research, it was established that the maximum permissible limit (for soil) of mobile compounds of lead (from 2.0 to 4.1 times), zinc (from 2.4 to 5.4 times), cadmium (from 1.9 to 2.5 times) was exceeded. and nickel (from 1.04 to 2.2 times) in all investigated bottom sediment samples. Exceeding the MPC (soil) for the content of gross forms of lead was found in five bottom sediment samples (from 1.1 to 1.5 times). Exceedings of the MPC of the soil by the content of gross forms of cadmium and manganese and mobile compounds of copper, nickel, cobalt and manganese were not detected. The maximum limit for the content of mobile compounds of iron and gross forms of zinc, copper, nickel, cobalt and iron is not regulated. The highest degree of contamination of bottom sediments by the content of: mobile compounds and gross forms of lead and nickel was found in samples taken from the bottom of a former limestone quarry (Kushugum village, Zaporizhzhia region); zinc — in a sample taken from the bottom of the former flood zone in the territory of the town of Balabyne and a sample taken from the open area of the Kakhovka Reservoir in the territory of the town of Malokaterynivka; cadmium — in the samples taken from the bottom of the former limestone quarry in the territory of the town of Balabyne and the sample taken from the open area of the Kakhovka Reservoir in the territory of the town of Malokaterynivka. According to the results of the correlation analysis, an extremely strong dependence was established between the content of mobile compounds of heavy metals and their gross forms — for cobalt (r=0.96), cadmium (r=0.92), nickel (r=0.91), lead (r=0.88) and zinc (r=0.84).

Indirect effects of oil products on the environment

The article is focused on chemical and radioactive contamination of the environment during hydrocarbon production. The objective of the research is to present relatively unknown facts of indirect long-term environmental effects of hydrocarbon production. Traces of radioactive contamination of soils, ground- and surface water were studied, and also in drinking water in the Republic of Bashkortostan. The authors’ own field and laboratory studies were used. They were performed as part of the preparation of geochemical base map (GHO-1000) of 1:1000000 scale in the Republic of Bashkortostan and in the Ukhto-Izhemsky oil and gas bearing region. The methods applied for laboratory research were inductively coupled plasma mass spectrometry (ICP-MS) for soil and bottom sediment samples and atomic emission spectrometry (ICP-AMS) for ground- and surface waters. It has been determined that in the areas affected by oil production the chemical pollution aspects include deterioration of the groundwater quality caused by associated water and oil products ingress into aquifers due to violation of the oil and gas well drilling techniques, and soil salination caused by frequent equipment breaks during oil production. Aspects of radiation contamination of the environment during oil production include the intake of radionuclides with associated water, and sometimes with heavy hydrocarbon fractions, as well as the consequences of underground nuclear explosions. It is concluded that the territories of hydrocarbon exploration, production and storage should be classified as areas of potential risk for radioactive contamination and chemical pollution (by inorganic compounds, including heavy metal salts). Uranium concentration in drinking water was determined by the INAA method (instrumental neutron activation analysis).

Fractionation of metals in bottom sediments of St. Petersburg rivers

Based on the method of successive extraction, the forms of heavy metals in the bottom sediments from eight rivers in the central part of St. Petersburg were studied. Watercourses are characterized by a high degree of technogenic pollution, the features of which are determined by the industry specialization of enterprises located on the banks of watercourses. Exchangeable forms, metals bound to carbonates, organic-sulfide (oxidized) fraction, bound to hydrate iron and manganese oxides (reduced) fraction, crystalline (acid) forms, and silicate (residual) forms were extracted from bottom sediment samples. A feature of urban precipitation was the predominance of residual forms and a high proportion of oxidized ones. Based on the methods of multivariate statistics (factorial and dispersion analysis), the technogenic geochemical specialization of different watercourses was established, the industrial and post-industrial (modern) horizons were identified in the section of bottom sediments, and the leading forms of metals were established. Sediments were characterized by a very wide range of total metal content. However, the dependence of the absolute content of metals in different extracts on the total concentration was contained only for Mn, Ni, Co, and Cd. Among the studied metals, the single-phase composition was found by Ba and Sr, which are 85–98% represented by the silicate form. ANOVA analysis of the metal content (without taking into account the residual fraction) showed that the accumulation of Cr, Cu, Zn, Mn, Co, Ni occurs in the oxidized form; for Ba and Pb, acid extraction plays a leading role; for Fe, the maximum concentration was found in oxidized and acidic extracts; for Cd, the exchange and carbonate forms are leading. A series of decrease in the mobility of metals Cd>Zn>Cr>Cu»Ni>Mn»Co>Pb>>Fe>>Sr>Ba indicated a high lability of chalcophile elements and a decrease in mobility in the series siderophiles - lithophiles. An expert assessment of the potential for secondary contamination of metals during bottom cleaning and soil dumping in the Neva Bay was obtained, which was especially significant for Zn, Cu, Cr and Mn.

Assessment of the using potential of water bodies clearance product – bottom sediments

Assessment of the using potential of water bodies clearance product – bottom sediments was carried out. Bottom sediments from Peschanyj, Dudak, Dudachenok shallow channels located at Volga-Akhtuba floodplain were used for studies. Bottom sediment samples were dried to an air-dry state at room temperature for further studies. The area of bottom sediments application was selected based on the physicochemical properties and the degree of it contamination by heavy metals and pesticides. Bottom sediments from Peschanyj and Dudachenok shallow channels have fertilizing value and correspond to calcareous sapropel of 1 and 2 suitability classes, respectively. Such bottom sediments can be used for agricultural aims.

Organochlorine compounds in the bottom sediments of the meromictic Mogilnoe Lake (Kildin Island, Russia)

The paper presents the results of a study of the behavior of organochlorine compounds (chlorinated benzenes and phenols) in the bottom sediments of Mogilnoe Lake (Kildin Island, Barents Sea). Mogilnoe Lake is a meromictic water reservoir located in the high latitudes of the Russian Arctic. A unique feature of the lake is its underground connection with the sea, which makes it similar to tropical anchialine lakes. Lake sediment samples were taken at three deep-water stations during complex expedition work in June 2019 by employees of the N. Laverov Federal Center for Integrated Arctic Research of the Ural Branch of the Russian Academy of Sciences (Arkhangelsk). Organochlorine compounds were extracted from air-dried samples of bottom sediments using accelerated flow-through solvent extraction with a hot mixture of organic solvents. Determination of the concentrations of chlorinated benzenes was carried out according to RD 52.24.417-2011 (RF), and the concentrations of chlorinated phenols and their derivatives – in accordance with the ISO 14154:2005. Quantification and identification of individual organochlorine compounds were carried out by capillary gas chromatography with electron capture detection. The presence of organochlorine compounds in sediments of the meromictic Mogilnoe Lake has been established. Concentrations of persistent organochlorine pollutants were assessed as high. Most likely, the component composition of organochlorine compounds and their detected levels (primarily pollutants) in the bottom sediments of the lake are due to the influence of various local anthropogenic sources, as well as atmospheric long-range transport from low/moderate latitudes and nearby regions.

Taxonomy of Ostracoda (Subfamilies Cytherurinae and Paracytherideinae) from the Southern and Eastern Brazilian Continental Shelves

A study on Holocene ostracods (subfamilies Cytherurinae and Paracytherideinae) was carried out in 500 bottom sediments samples recovered along the Brazilian continental shelf from Rio Grande do Sul (33º45’S/52ºW) to Espírito Santo (19º35’S/40ºW) states. New species belonging to the subfamily Cytherurinae are here identifi ed and described as follows: Eucytherura rara sp. nov., E. trifi da sp. nov., E. castellata sp. nov., and Semicytherura reticulocostata sp. nov. Three other species are kept in open nomenclature due to scarcity of material for study: Semicytherura sp. 1, Semicytherura sp. 2 and Hemingwayella sp., the last one representing the subfamily Paracytherideinae. The zoogeographical and stratigraphical analyses revealed that most of the species identifi ed do not exceed the latitude 19º30.1’S with the southernmost record at 33º52’S; some of these species extending to the Uruguayan and Argentinian shelves. Exceptions are the species Semicytherura parallelocostata and Semicytherura sp. 2 that reach the northeast and equatorial Brazilian continental shelves at latitudes 10º32’S and 00º08’S, respectively. Two of the studied species have a fossil record in the Pelotas Basin (Brazil): Hemicytherura auriculata (Miocene and Pleistocene) and Semicytherura rugosoreticulata (Holocene). Hemicytherura lapillata has been recorded in a Holocene outcrop in Bahia Blanca (Argentina).

Changes in the Baltic Sea levels during the Late Pleistocene the Late Pleistocene-Holocene transition

The article discusses the Pre-Baltic Sea history during the Late Pleistocene and Holocene periods. Despite a long history of research on this topic, there are still gaps in our knowledge that prevent us from creating an accurate and comprehensive paleo geographic reconstruction of the region during this time period. A table that provides information on the dates of bottom sediment samples from lakes, peat bogs, and archaeological sites that mark the earliest stages of Baltic Sea evolution, is included. The article identifies problems with the limited research on the Baltic Glacial Lake and Ioldium Sea sediments, as well as the maximum extent of the Ancylian transgression. A brief chronology of changes in water levels during the earliest stages of the Baltic is presented.

Bottom sediments of the Shershnevskoye reservoir: Physicochemical characteristics and toxicity

The Shershnevskoye reservoir (ShR) is the main source of drinking water supply for the city of Chelyabinsk, which, since 2003, has been experiencing serious environmental problems caused by eutrophication processes. The purpose of this work was to study the bottom sediments (BS) of the ShR. BS were sampled in 4 locations of the ShR in the spring of 2024. We determined the 5 physicochemical parameters of the BS, the content of humic substances and gases (CO, CO2, CH4), 25 hydrochemical parameters and the toxicity of pore waters. It has been established that the bottom sediments of ShR are sandy silt, they have an average density of 1.008 g/cm3. In the longitudinal section of the reservoir, a trend towards an increase in the content of organic matter and methane in the BS from the upper reaches to the dam is observed. The pore waters belong mainly to the first (I) hydrochemical facies (Ca2+–Mg2+–Cl-–SO 2-) according to the Back (1961) classification. In the reservoir section, there is a clear trend of replacing bicarbonate ion with sulfate ion, and the concentration of chloride ion was minimal (from 0.1 to 1.1 mg/L). According to the results of biotesting using Scenedesmus quadricauda and Daphnia magna, all BS samples exhibit chronic toxicity, and two samples also exhibit acute toxicity, probably associated with the release of toxic products of organic matter mineralization.

Occurrence, Distribution, and Trophic Transfer of Pharmaceuticals and Personal Care Products in the Bohai Sea.

The ubiquitous presence of pharmaceuticals and personal care products (PPCPs) in environments has aroused global concerns; however, minimal information is available regarding their multimedia distribution, bioaccumulation, and trophic transfer in marine environments. Herein, we analyzed 77 representative PPCPs in samples of surface and bottom seawater, surface sediments, and benthic biota from the Bohai Sea. PPCPs were pervasively detected in seawater, sediments, and benthic biota, with antioxidants being the most abundant PPCPs. PPCP concentrations positively correlated between the surface and bottom water with a decreasing trend from the coast to the central oceans. Higher PPCP concentrations in sediment were found in the Yellow River estuary, and the variations in the physicochemical properties of PPCPs and sediment produced a different distribution pattern of PPCPs in sediment from seawater. The log Dow, but not log Kow, showed a linear and positive relationship with bioaccumulation and trophic magnification factors and a parabolic relationship with biota-sediment accumulation factors. The trophodynamics of miconazole and acetophenone are reported for the first time. This study provides novel insights into the multimedia distribution and biomagnification potential of PPCPs and suggests that log Dow is a better indicator of their bioaccumulation and trophic magnification.

Heavy Metal Contamination in the Jandiá Canal, Municipality of Macapá-AP, Brazilian Amazon

Objective: Evaluate contamination by heavy metals: Cadmium (Cd), Lead (Pb), Chromium (Cr), Manganese (Mn), Copper (Cu) and Nickel (Ni), from Canal do Jandiá, Macapá-AP. Theoretical framework: This study based on theoretical reflections on environmental issues, the relationship between society and nature. The problems of heavy metals in the environment, environmental toxicity, and the uses of water. Method: Techniques such as bibliographic and documentary research; information inventories; collection and analysis of bottom sediment samples. Collections were at 3 (three) points at the mouth of the channel, one on the channel bed and one on the Sérgio Arruda Bridge. An Atomic Absorption Spectrophotometer from the Atomic Absorption and Bioprospecting Laboratory (LAAB). Results and conclusion: Observed that Cd, Pb, Cr and Ni presented values ​​above those stipulated by legislation. And that seasonal variation contributes to the increase in the concentration of the metals Cd, Cr, Cu, Mn and Ni in the bottom sediment. Implications of the research: This study will contribute to public policy measures, helping decision-making for environmental improvement in the municipality of Macapá-AP. Originality/value: This research is of socio-environmental and scientific importance, as it evaluates the concentration of heavy metals and associates it with the lack of environmental sanitation and rainfall in the region.

Novel Use of Microbial Hydrocarbon Detection Technology in Reducing the Risk of Nonhydrocarbon Exploration in Oil and Gas Exploration in the South China Sea

Summary As the exploration of the South China Sea continues into deeper water, the chances of encountering nonhydrocarbon gas (CO2, N2, etc.) reservoirs rise. The question of how to avoid the risks associated with the discovery of nonhydrocarbon gas reservoirs becomes an issue for deepwater (DW) oil and gas exploration. Geomicrobial hydrocarbon detection (GMHD) is a nonseismic hydrocarbon detection technology that is able to predict the hydrocarbon potential of a prospective area at depth. This is accomplished via the detection of specific hydrocarbon-oxidizing bacteria in both onshore soils and offshore sea bottom sediment samples. The effectiveness of this method has been proved repeatedly in DW explorations of the northern South China Sea. It documents a possible solution to nonhydrocarbon gas risk prediction by combining the oil and gas prediction results of geomicrobial hydrocarbon detection with results from geological and geophysical studies to analyze the different microbial responses above nonhydrocarbon gas and hydrocarbon gas reservoirs. This was verified in the DW exploration practices undertaken in the Pearl River Mouth Basin and Qiongdongnan Basin of South China Sea.

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.

Retrieval of suspended sediment concentration (SSC) in the Arabian Gulf water of arid region by Sentinel-2 data

Suspended sediment concentration (SSC) in water increases temperature and turbidity, limits the photosynthesis of aquatic plants, and reduces biologically available oxygen. It is important to study SSC in the coastal waters of the Arabian Gulf. Thus, this study mapped the SSC of coastal water between Al Arish and Al Ghariyah in northern Qatar using the spectral bands of the MultiSpectral Imager (MSI) of Sentinel-2 by calculating the Normalized Difference Suspended Sediment Index and Normalized Suspended Material Index. The results are studied using the Normalized Difference Turbidity Index and Modified Normalized Difference Water Index. The mapping of SSC in the water using NDSSI showed the presence of a high concentration of suspended sediments between Al Arish and Al Mafjar and a low concentration between Al Mafjar and Al Ghariyah. The mapping of NSMI showed values between 0.012 (clear water) and 0.430 (more suspended material) for the occurrence of suspended materials and supported the results of NDSSI. The study of turbidity using an NDTI image showed turbidity index values ranging from −0.44 (clear water) to 0.12 (high turbidity) and confirmed the occurrence and distribution of suspended sediments and materials in the water. The MNDWI image was able to discriminate clear water with bright pixels from silty sand and mud flats. The relationships between NDSSI, NSMI, and NDTI were correlated with in-situ measurements and studied to find suitable indices to map SSC. Regression analyses showed the strongest relationship between NSMI and NDTI (R2 = 0.95) next to NDSSI and NDTI, where NDTI had the strongest effect on NDSSI (R2 = 0.86). The satellite data results were evaluated by studying the physical parameters and spatial distribution of suspended sediments in the surface and bottom waters. In addition, the grain size distributions, mineral identification, and chemical element concentrations in the bottom sediment samples were studied.

Variability and Heavy Metal Pollution Levels in Water and Bottom Sediments of the Liwiec and Muchawka Rivers (Poland)

In recent years, human impact on the Earth’s ecological environment has become increasingly visible, with serious negative consequences. One of the most important pollutants are heavy metals which can easily bind to sediments. Due to their toxic behavior, persistence, lack of biodegradability and bioaccumulation, they are considered key river pollutants that need to be controlled. This study examined two rivers: the Liwiec and Muchawka rivers located in south-eastern Poland. The mouth of the Liwiec River is the Bug River, which is partly the border between Poland and Belarus. In turn, the mouth of the Muchawka River is the Liwiec River. The objectives of the study were the following: (1) To complete a qualitative analysis of heavy metals (Cd, Pb, Cu, Ni, Zn) in the waters and bottom sediments of the Liwiec and Muchawka rivers; (2) To assess the degree of heavy metal contamination; (3) To identify the sources of contamination. The analysis included samples of surface water and bottom sediments collected (16 water and 16 bottom sediment samples were taken from the Muchawka River and 32 water and 32 bottom sediment samples were taken from the Liwiec River) in June and September 2022. The variability of characteristics, such as temperature, precipitation and humidity, contributes to seasonal changes in the distribution characteristics and sources of heavy metals. The study showed that only a small part of the heavy metals entering rivers are present in the water depth in the dissolved state, and most of them enrich the sediment, resulting in much higher concentrations of heavy metals in the sediment than in the water column. The differences in the distribution of some elements in water and sediment are due to the fact that surface sediments retain long-term records. Therefore, sediment can be considered a potential source of heavy metals in the aquatic environment. In general, the content of heavy metals determined in bottom sediments was not high but indicative of anthropogenic human activity. There is a possibility of re-release of heavy metals from the sediment into the water when hydrodynamic conditions or environmental factors (pH, redox potential, etc.) change, which could lead to secondary water pollution. The data obtained will be of great importance to both researchers studying river systems and the population living in the area.

New data on the transformation of water and sediment runoff into the Lena river delta based on the results of expedition measurements in August 2022

Field hydrological measurements were performed in the Lena River delta from the 10th to the 16th of August 2022. 25 values of water discharge and 58 suspended sediment concentrations (SSC) were measured, multiple chemical composition water samples were taken, along with samples of bottom and bank river sediments, and thermal abrasion coasts were highlighted. Particle size and chemical composition analyses of the sediment samples were carried out. The aim of the study was to estimate the water flow distribution in the delta and to determine the directional SSC, sediment particle size and chemical composition changes along the delta and inside the depth of the river flow, and define the roles of the local hydrological and morphological factors of river flow transformation. Moreover, field measurements are crucial for SSC estimation and monitoring based on satellite image data. The laboratory analyses included particle size definition in suspended and bottom sediment samples, organic matter and SSC definition. The August 2022 expedition results were compared to the previous surveys. It was established that the flow distribution around the Stolb island corresponds with that of 2016: the Bykovsky, Trophimovsky, Tumatsky and Oleneksky branches receive 24.9–25.5, 58–59.2, 6 and 6.6 % of the water discharge from the Kusur gauging station on the Lena River, respectively. However, the role of the Main channel was slightly overestimated. The new data includes water discharges in the branches around the Samoilovsky island and in the channel systems of the Oleneksky and Tumatsky branches. SSC was relatively low and amounted to around 12–24 mg/l, rising from the water surface to the bottom 1.2–2 times. SSC decreased along the course of the Oleneksky and Tumatsky branches (1.5 and 1.1 times, respectively) due to the ratio between SSC and the potential stream transport capacity. SSC rose along the course of the Bykovsky branch, even though it wasn’t shown by the Landsat-8 satellite image (16th of August 2022). A significant sediment source in the delta are eroded and thermo eroded shores of the edoma island systems. The average sediment size proved to be from 0.011 to 0.019 mm. SSC does not vary much around the main channel and the nearest branches. Important relations between SSC, optical turbidity and ADCP backscatter intensity were estimated. The coarse diameter of 30 bottom sediment samples was 0.46 mm. The largest sediments were discovered in the Bykovsky branch, while the smallest sediments were found in the smaller transverse branches. Along the Tumatsky and Oleneksky branches the bottom sediments alternate from fine to medium sands.

Assessment of Microplastic Degradation in Bottom Sediments Using Raman Microspectroscopy and Atomic Force Microscopy

The assessed degradation of microplastics from bottom sediments of the Laptev Sea, the Weddell Sea, the Chukchi Sea and Peter the Great Bay, Sea of Japan, was studied using Raman microspectroscopy and atomic force microscopy (AFM). The degree of amorphous-crystallinity of polyethylene terephthalate (PET) was determined by the ratio of Raman mode intensities (I1095 cm–1 / I1115 cm–1). Changes in the topography and mechanical properties of the surface of polymer fragments were studied by AFM methods. It has been shown that the degradation of PET found in the bottom sediments of the Laptev Sea affects mainly its crystalline phase. The amorphous phase of PET is affected to a much lesser extent or not at all. The same changes in the phase composition of the PET surface have been shown after plastic exposure in a marine aquarium in silty sand from the Amur Bay (Peter the Great Bay, Sea of Japan). AFM data show an increase in PET surface roughness and a decrease in elasticу modulus (Young’s modulus) in bottom sediment samples. Raman microspectroscopy also shows signs of degradation of cellophane fragments from the Weddell Sea, polyvinyl chloride (PVC) from the Laptev Sea, and polyethylene (PE) from the Amur Bay.

USING RADIOISOTOPE METHODS TO DATE Cs INFLOW TO BOTTOM SEDIMENTS OF THE YENISEI RIVER

The long-term study of samples of bottom sediments (BS) of the Yenisei River revealed the presence of a unique set of artificial radionuclides (Co, Cs, Eu, Eu), which made it possible to combine different methods for calculating sedimentation rates for a retrospective assessment of river BS. Studies have been carried out to determine the sedimentation rates by various methods, using natural non-equilibrium Pb, the ratios of artificial isotopes Cs/Co and Eu/Eu, and marker Co, in several sections of the Yenisei River - downstream of the radioactive discharges of the Mining and Chemical Combine (MCC) of Rosatom near the villages of B. Balchug and Atamanovo, as well as upstream of the MCC discharges in the reference areas near the villages of Esaulovo and Shivera. Estimation of sedimentation rates using non-equilibrium Pb, Cs/Co and Eu/Eu isotope ratios, and marker Co for reference areas and the areas near villages located downstream of the MCC showed that their values lay in the range of 0.5-1.3 cm/year. A chronology of Cs influx into BS was constructed using different radioisotope methods, which demonstrated that the maximum Cs influx into BS in the reference regions of the villages of Esaulovo and Shivera and in areas of the village of B. Balchug was noted during the extreme flood of 1966. Cs maxima were also found in the BS layers whose dating coincided with the floods of 1988 and 1995-1997.

Evaluation of radioactive properties and microfaunal evidence in the Bosphorus and the Dardanelles straits and Golden Horn sediments

The aim of this study is to investigate radioactive pollutants from pollution loads transported from the Black Sea to the Aegean Sea by the Turkish Straits System and their effects on microfauna (benthic foraminifer and ostracod) assemblages. In the study, the effects of gross alpha and beta activity on the species number, species diversity, dominant species and species richness of benthic foraminiferal and ostracod assemblages were investigated in 16 bottom sediments taken from different depths in the Golden Horn, Bosphorus and Dardanelles straits. In the studied sediment samples examined 61 genera and 64 species of benthic foraminifera, 23 genera and 26 species of ostracoda were identified. In addition two migratory foraminifera species were observed as Spiroloculina antillarum of Atlantic-Pacific origin and Peneroplis pertusus of Indo-Pacific origin. A relationship between the abundance of microfauna and high gross alpha and beta values was found in the Dardanelles samples, but not in the Bosphorus and Golden Horn samples. In this study, the highest radioactivity value was observed in the deepest bottom sediment samples. Consequently, the gross alpha and beta values were seen to be close to each other in the Dardanelles Strait and Golden Horn samples, and they had a broad-spectrum in the Bosphorus samples.

Particle-based nutrients and metal contaminants in the habitat of Unionidae mussels in the Tisza River (Hungary)

Introduction:Unioniade is a species-rich family of freshwater mussels with an almost worldwide distribution. In Central European rivers Unio crassus, Unio tumidus and Unio pictorum have relatively high populations. In order to characterize the habitats of these suspension feeders, their nutrient supply and potential metal contaminants were investigated in near-bottom suspended (NBS) sediments and bottom sediments (BS) collected at four sampling locations along the Tisza River.Methods: The grain size distribution of sediments was determined by laser-diffraction technique. The total organic carbon (TOC) and the total Kjeldahl nitrogen (TN) were measured by a TOC analyzer and automated colorimetry, respectively. The phosphorous and metal concentrations were determined by inductively coupled plasma mass spectrometry following a microwave assisted acidic extraction of sediments with aqua regia.Results: The NBS sediments contained smaller grains than the BS samples, with roughly 85%–90% of the particles being less than 60 μm, allowing these mussels to catch them. Contrarily, only 2.47%–51.8% of BS samples were less than 60 μm. The NBS sediments contained 30, 23, and 15% more organic carbon, nitrogen, and phosphorous, respectively, than the BS samples. The rounded C:N:P molar ratios in the NBS sediments were 60:4:1, whereas they were 45:3:1 in the bottom sediments. The concentration of metals was also greater in the NBS sediments with the exception of Zn at Tokaj and Fe, Al, Mn, and Cr at Szeged, where prior contaminations transported by the tributaries Bodrog and Maros are stored in the top 10 cm of BS.Discussion: On basis of the measured C:N:P molar ratios it can be stated that soil-derived organic materials are the main sources of the nutrient elements in the habitats of suspension feeders in the Tisza River. The finer NBS sediments have higher specific surface area than the BS and thereby contain more biofilms on the grains resulting in higher proportion of organic nutrients and metal ions bounded as complexes or chelates. Comparing the measured metal concentrations of sediments with the concentration limits summarized in the Consensus-Based Sediment Quality Guidelines developed for evaluation of potential risk of metal contaminants in sediments for the benthic-dwelling organisms, it can be established that only the Hg concentration exceeded the probable effect concentration.

Assessment of heavy metal pollution and quality in lake water and sediment by various index methods and GIS: A case study in Beyşehir Lake, Turkey

Beyşehir Lake, Turkey's largest freshwater lake, is also a “Drinking Water Reserve”. In the study, heavy metal (As, Cr, Cu, Ni, Zn, Pb, Cd, Hg, Fe, Al, Mn) concentrations of seasonal lake water and bottom sediment samples were determined to evaluate the heavy metal pollution. Several index methods were applied, and pollution assessments were made using the obtained analysis results of lake water and sediment samples. The average concentrations of the heavy metals in the lake waters are observed as Fe > Al > Mn > As>Zn > Ni > Pb > Cr > Cu > Hg > Cd. When the lake waters were compared with the TS 266 (2005) and WHO (2017) limit values, it was determined that lake waters are below the limit values in terms of the heavy metals. According to index results, all of the lake samples are suitable for use as drinking water in accordance with the heavy metal pollution index (HPI) value, all of the samples are in the “low pollution” class in accordance with the heavy metal evaluation index (HEI) and degree of contamination (Cd) values. In addition, the water average concentrations of the heavy metals in the lake sediments are observed as Fe > Al > Mn > Cr > Ni > Zn > Cu > As>Pb > Cd > Hg. The contamination factor (CF) and enrichment factor (EF) revealed that sediments were considerably and moderately polluted by As, Cr, Cu, Ni, Cd, Fe and Mn and low polluted and/or unpolluted by other metals. The calculated pollution load index (PLI) and Igeo values indicate that lake sediments do not carry a risk of heavy metal contamination.