Heavy metals distribution in water and soil of the coastal zone of the Styr River (Ukraine) and its tributaries

Abstract

Investigation of the peculiarities of chemical contamination of water and soil in the coastal zone of the river Styr and its tributaries in relation to the distance from the source of pollution and the type of landscape, analysis of the general trends in the distribution of chemical elements in comparison with the control site. Statistical processing of parameters of chemical contamination of water and soil; data mining methods; correlation analysis; assessment of ecotope similarity and grouping of chemical elements based on cluster analysis; multidimensional ordination of ecotopes in the space of geochemical parameters based on Principal Component Analysis. Chemical contamination of water and soil in the coastal zone of the Styr River and its tributaries is characterised by significant heterogeneity. The main feature of the increasing intensity of anthropogenic load on the aquatic environment is associated with an increase of Cu, Zn, Pb, Mn content compared to the natural background. The intensity of soil pollution in the coastal zone of the Styr River and its tributaries mainly depends on the presence of Cu, Cd and Ni. The analysis of the relationship between chemical elements concentrations indicates a strong dependence between many parameters. Based on the similarity of chemical elements in terms of their distribution in the water of the river Styr and its tributaries, 4 associations (groups) were identified: I – Cu, Mn; II – Zn, Pb; III – Cd, Cr, Sr; IV – Co, Ni. For the soils in the coastal zone, 3 associations (groups) of chemical elements were identified: I – Cu, Cd; II – Zn, Mn; III – Cr, Co, Ni, Pb. Three groups of sites of the Styr River and its tributaries were identified according to the pollution rate of water and soils of the coastal zone with heavy metals. The multidimensional ordination of the ecotopes of the Styr River and its tributaries on the axes of complex geochemical environmental gradients reflects the gradients of water and soil pollution in the coastal zone compared to the control areas. Geochemical information visualisation based on two-dimensional diagrams with chemical element concentrations or complex environmental gradients as axes can be used to predict the dynamics of ecosystem components as a result of changes in chemical pollution. The practical relevance of the obtained results is that forecasting of dynamic trends, protection and restoration of ecosystem components is impossible without taking into account their interrelationships with environmental conditions, including chemical pollution. Knowing the geochemical conditions of ecotopes in a certain period of time, it is possible to determine their position in the ecological space on the complex gradients of the environment of the Styr river and its tributaries, to predict the stability and possible changes in vegetation, fauna and microflora caused by environmental pollution.