Mercury Content in the Soil-Vegetation Cover of Russky and Shkot Islands (Peter the Great Bay, Primorsky Territory)

The ecological situation on Shkot Island and the adjacent part of Russky Island in terms of mercury content in soils and leaves of tree and shrubbery vegetation has been analyzed. The main sources of mercury input into geosystems have been revealed. To determine its content in soils and vegetation, 3 and 16 plots have been sampled on Russky and Shkot islands, respectively. It is shown that the soil cover of Russky and Shkot islands is represented by typical and dark brown burozems (brown forest soils) and their pyrogenic analogues. Mercury distribution depends on soil properties in a soil cover and on plant species in vegetation. The results of laboratory research of mercury content in geosystems are presented. Using interpolation method, maps of mercury content in the soil cover and oak leaves (Quercusmongolica) have been compiled for Shkot Island. The average mercury content in the soil cover of Shkot Island and the adjacent part of Russky Island is 81.2 ng/g. The average contents in various plant species are as follows: 26.3 ng/g for Carpinus cordata, 24.5 ng/g for Quercusmongolica, 9.1 ng/g for Artemisia gmelinii. Such variations are caused by different mercury accumulation ability of the plant species. It is assumed that the high mercury content in the soil and vegetation in the eastern part of Shkot Island is due to tectonic features. The maximum soil mercury content on Shkot Island is confined to the Dotovaya Bay coast, which is the island's main recreation area in summer. Numerous campfires and wood and household waste (first of all, polyethylene) combustion lead to mercury redistribution in the adjoining territories. In terms of mercury content, the ecological setting in the soil-vegetation cover of Russky and Shkot islands is viewed as favorable. The mercury content in soil is much below maximum permissible concentration. Since maximum permissible concentration of mercury in plants is not available, the comparison has been carried out for Clarke values. The mercury content exceeds Clarke values for Carpinus cordata and Quercusmongolica, which can be attributed to natural regional specifics. The obtained data can be used as background indicators.