Abstract
This study focuses on metal speciation research in Arctic lakes with technogenic pollution and other areas where natural processes prevail (background lakes and lakes with marine influence). ...Element speciation in 75 lakes in the Kola Peninsula was investigated in 2014 and 2018 taking into account the influence of different geochemical factors. The geochemical features of lake water in the investigated regions are documented and discussed. Membrane filtration was used with the following features: mechanical suspension and oxidized contaminants (>8
μ
m, 1.2
μ
m) for lakes near smelters and those subject to marine effects; light suspension colloids (0.45–0.1
μ
m) for the natural waters of background lakes; low molecular weight complexes, inorganic ions, bacteria, and viruses (less than 0.1
μ
m) for identification of labile and non-labile components. It has been proven that the bioavailable speciation (unbound with organic components) is determined by the physicochemical properties of organic matter, such as zeta potential, molecular weight, and colloid stability. In conventional background lakes, Fe and Al complexes with humic substances dominate, and the most associative elements of the lanthanide/actinide group repeat the tendency of Fe. In lakes with a clear marine influence, the complexation potential of organic substances is reduced due to Na ions, which deactivate humic functional groups. Multivariate statistical methods showed significant differences between the selected gradations of lake waters and the genetic similarities and differences in the behavior of element speciation.
This paper presents metal speciation calculations that are based on mathematical modelling of chemical reactions in natural waters. Metal concentrations (Hg, Cd, Pb, Ni, Cu, Al, Sr) were determined, ...and their speciation in water were calculated for 22 water areas in the Kola region. Meanwhile, the accumulation of metals in fish organs and tissues was studied (e.g. whitefish). The biogeochemical activity of metals determines the proportions of labile and non-labile speciation in water. In the distribution zones of non-ferrous industry effluents, metal aqua-ions prevail; during the distribution, the proportions change in accordance with the metal activity. The bioavailability of metal speciation is estimated depending on aqueous geochemical conditions and, accordingly, the speciation of metals (in situ), based on the original studies of the lakes of the Kola region in northern Russia. The connection among the metal contents in fish and water has been identified using multidimensional scaling and redundancy analysis techniques. Using the example of natural conditions in northern low-salinity freshwaters, it is demonstrated that labile Cd, Pb, Ni, Cu, Al, and Sr are the species most bioavailable and able to penetrate fish; meanwhile, the organic complexes of Hg, Pb, and Al have a greater affinity to accumulation in the gills. This study demonstrates the need to correct the approved water quality standards in Russia, taking into account the high bioavailability of metals in northern low-salinity waters.
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The paper discusses variations in the migration activities of elements in parent rocks of soils under the effect of anthropogenic and geochemical factors. The unique geological characteristics and ...the diverse mineral resources of the study area predetermined the high susceptibility of water bodies in the Kola Peninsula to influences of parent soil-forming rocks at watersheds and to anthropogenic impacts. Selected typical alkaline and acid rocks of the area were used in static and dynamic experiments on leaching elements from these rocks. The extracting agents were doubly distilled water, sulfuric acid, solutions of fulvic acids, and solutions of fulvic acids after their degradation by sulfuric acid. The results show differences in the extraction of trace elements from rocks by the various extraction agents: the water extracts are characterized by the maximum recovery of some elements in experiments with alkaline rocks (the extraction Ni and Cu was four- and threefold greater than in the other experiments), and extracts by sulfuric acids from acid rocks resulted in higher concentrations of U (twofold) and Cu (less than one order of magnitude). Fulvic acids most strongly affect all of the studied rocks. According to data of discriminant analysis, the greatest contributions (with a coefficient close to 10) to the discrimination is made by the following parameters: trace elements of the La group, heavy-metal ions (Ni, Cu, and Pb), and pH.
—Data on the influx and behavior of humus substances in natural waters are considered. The widest spread methods of analyzing physicochemical properties of natural polymers causing their interaction ...with metal ions are analyzed. The concept of metal complexation with humus substances at different chemical equilibria is developed on the basis of original and an available literature review evaluating the metal speciation in natural objects (lakes, rivers, seas).
The distribution of trace elements of anthropogenic origin, especially toxic metals, is an environmental problem. We present the first results of research into the geochemistry of lake waters and ...metallic pollution in European Russia (ER) and Western Siberia (WS), based on a survey of 367 lakes from the tundra to the steppe zones. The content of more than 80 elements in the lake water was studied; the influence of airborne contamination and the geochemistry of water were estimated. We found that the concentrations of alkaline and alkaline-earth elements, as well as As, V, Co, U, Nb, Sb, increase with a change in the climatic gradient. This fact is explained not only by airborne contamination, but also by the geochemistry of lakes and the climatic factor (increased evaporation concentration). Anthropogenic eutrophication leads to an increase in the content of Fe, Sr, Mo, and acidification-Zn, Cd, Ni, Cu, and especially Pb. There are industry-specific influences: the waters of the northern regions of ER are enriched by Ni, Cd, As, Sb and especially Se because of the emissions from copper-nickel smelters. The oil and gas industry (WS) leads to increased concentrations of V, Pb and Mo in water. We assess the metallic pollution status of surface water in the Eurasian region of Russia using an enrichment factor (EF). In surface waters of ER and WS, metal concentrations do not exceed the maximum permissible concentration, but we have established higher concentrations of many elements in the background, including toxic ones. Prolonged low doses of toxic elements can be a potential hazard to ecosystems and humans. The results showed that from the northern to the southern regions the EF increases for most of the analyzed elements. It can be assumed that with climate warming the concentration of metals in these bodies of water will increase and this is dangerous for the environment.
This paper considers the element distribution between species in the lysimetric waters and lakes of the Valdai National Park in different seasons. Seasonal studies of natural waters and element ...speciation in them in 2019 using membrane filtration and ion-exchange separation showed the differences in the seasonal distribution of species depending on geochemical factors. The seasonal temperature factor causes a change of metal speciation from suspended (after meltwaters) through soluble mainly organic (summer) to inorganic/organic low-molecular (autumn) forms. The humus content in the water objects affects the transformation of colloid systems.
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The paper discusses the distribution and origin of organic matter in natural waters with regard to the latitudinal geographic zoning in the European territory of Russia (ETR) and Western Siberia ...(WS) and demonstrates how conditions on the catchments and climate affect the content of autochthonous and allochthonous organic matter. Conditional coefficients of the ratios of these forms are calculated. The influence of the temperature factor on the content of autochthonous organic matter in the waters of the southern territories of the ETR and WS was proved by multivariate statistical methods of analysis. General trends and relations are identified in the distribution of lipids, proteins, and carbohydrates of the autochthonous and allochthonous organic compounds. The mechanism of biochemical transformation of bound carbohydrates of allochthonous organic compounds into free autochthonous ones via the microbial decomposition is demonstrated, which is more typical of waters in the southern regions of WS. The paper discusses how natural and climatic conditions can influence changes in concentrations of organic compounds in the lake waters and structural characteristics of these compounds (contents of aromatic and aliphatic fragments).
Acidic deposition has caused severe surface water acidification in Europe and North America, but surface water acidification has not been systematically studied in Russia. Here we present the first ...detailed study on regional surface water acidification in European Russia (ER) and Western Siberia (WS) based on a survey of 367 lakes in a transect from the tundra to the steppe, which were investigated to explore the status and mechanism of surface water acidification. The variability of water chemistry is documented and discussed. High pH and acid-neutralizing capacity (ANC) were observed for lakes in the southern region, indicating that surface water acidification does not occur here. Anthropogenic acidification occurs in the humid areas of both regions, being observed in 4.4% of ER and 8.2% of WS lakes. These tundra and taiga lakes are characterized by high transparency, low pH, and ANC with a high concentration of strong acid anions. The main factor leading to acidification in the ER lakes is sulfur emission from metal smelters whilst that in WS is acidification, likely associated with gas burning by oil production facilities. In the ER acid lakes, SO42− is dominant; this is in contrast to WS, where NO3− and Cl− are dominate. The influence of strong technogenic acids on the structure of organic components and their possibility to form a proton is discussed. The phenomenon of the increase in water acidification by organic acids and strong acids is explained. These results clearly show the effect of a number of factors that strengthen the acidity of water. Differences in the chemical composition of lakes of both regions, as well as differentiation by their acid properties, were statistically proved. Results of our research indicate the need to reduce emissions of acidic gases into the atmosphere.
Natural and anthropogenic factors affecting the composition of waters of the Arctic mountain lakes of the Khibiny alkaline massif were determined and the impact of global climatic and environmental ...changes on the functioning of primary producers, phytoplankton, was estimated. The geochemical, climatic, and morphometric features of the catchment area of the territory and basins, as well as anthropogenic load were characterized. It was established that the waters of the Khibiny lakes have hydrocarbonate–sodic composition, neutral and weakly acid pH values, low mineralization and concentrations of trace elements, and relatively elevated contents of K
+
cation. Based on the extremely low contents of nutrients and phytoplankton, the studied lakes are classed as oligotrophic. Metals mainly occur as ions due to the low content of organic matter. Phytoplankton represented by typical Arctic species is characterized by the poor species composition and low quantitative parameters. It was revealed that pH value, mineralization, content of major ions and trace elements, and quantitative parameters of phytoplankton decrease, whereas, the fraction of sulfate fraction in anion composition increases with increasing altitude of the lakes. The influence of atmospheric emissions from the adjacent Severonikel and JSK Apatit enterprises causes an increase of Cu, Ni, Zn, and Sr contents, as well as nitrogen compounds in lake waters. An increase of heavy metal content (Ni, Cu, Pb, Cd, Hg) in the surface layer of bottom sediments of mountain lakes reflects the anthropogenic impact from local productions and transboundary transport of contaminants in the high atmosphere layers. In addition to the accumulation of heavy metals, the bottom sediments show an increase of population and change of species diversity of diatoms, which likely reflects an increase of open-water period owing to the present-day climatic changes in Arctic.
The paper reports chemical data on the atmospheric precipitation within the studied area of the Valdai National Park during monitoring in 2015–2018. The main parameters of atmospheric precipitation ...as well as major and trace-element compositions of waters are analyzed. Seasonal dynamics and possible pathways of element uptake in atmospheric precipitation are considered. Multidimensional statistical analysis (PCCA, RDA analyses) was applied to determine geochemical and anthropogenic factors responsible for the formation of the chemical composition of atmospheric precipitation. Precipitations penetration through tree crown are enriched in organic matter and some elements. The high contents of N, Fe, Mn, Zn, and Cu found in subcrown waters indicate a predominant biogenic migration of the elements with atmospheric fallouts. The elevated contents of Cu and Zn, as well as Cd and Pb in the atmospheric fallouts of the Valdai National Park suggest that the studied area experiences a regional-scale anthropogenic load.
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