Landscape-biogeographical aspects of heavy metals accumulation and migration in Arctic and Subarctic soils of the European Northeast

The implementation of the tasks of social and economic development of the Arctic zone of Russia provides for intensification of extraction of fuel and energy resources, their complex processing and creation of appropriate infrastructure. In these conditions, there is increased attention to the assessment of the current state of natural ecosystems of the Arctic and sub-Arctic sectors of the European northeast, including the Bolshezemelskaya tundra. The soil cover of the Bolshezemelskaya tundra is largely understudied as the area is of difficult access. Soils of the south-eastern part (within Vorkuta industrial hub), the north- western part (the Pechora and Ortina rivers basins) and the southern part (the Kolva river basin) of the Bolshezemelskaya tundra are the most thoroughly studied. Northern regions of the Bolshezemelskaya tundra confined to the northern (typical) tundra, are characterized by sporadic descriptions of soils and are practically nonstudied concerning distribution of heavy metals.The data characterizing soils of the northern part of the Bolshezemelskaya tundra are presented. The studies were carried out on the territory of the Nenets Autonomous Area and the basins of Chernaya and Khudaya (the Barents Sea basin) which geocryological conditions are determined by continuous distribution of permafrost. Here on watersheds and preriver landscapes soils of the semi-hydromorphic and cryo-hydromorphic type dominate. Systematic list of soils on the territory under consideration includes 15 types and 25 subtypes. The assessment of background concentrations of heavy metals (Cu, Pb, Cd, Zn, Ni, Co, V, Mn, Cr, Fe, Sr, Ba, Mo) and metalloids (As) for the most distributed podburs, gleyzems, peatgleyzems, peat soils of wetland complexes and alluvial soils of valley landscapes of the rivers was carried out. The limits of their variation and profile distribution are set. It is shown that the content of principal pollutants (Hg, Pb, Cu, Ni and Zn) in soils of background landscapes of the Bolshezemelskaya tundra is much less than the standards of the Russian Federation on their approximate permissible concentrations (APC). Noted in some cases exceeding of permissible concentrations of As, Co, Mn and Cd is caused by the specific composition of the soilforming rocks and specificity of conditions of accumulation and migration of elements in permafrost landscapes. In general, most metals are characterized by low and average regional level of their content in the soils of the northern part of the Bolshezemelskaya tundra. For cadmium and arsenic the increased and high regional level of their content in soils is identified.The specific feature of the northern tundras of the Bolshezemelskaya tundra is extremely low content of molybdenum in soils - in most of the investigated soils its content was at the level less than the lower estimation level. The differences in the content of heavy metals (Zn, Pb, Ni, Cu, Cd, Hg) and arsenic (As) in organogenic horizons of soils of the southern shrub and northern hypo-Arctic tundra are revealed. It is shown that in the direction to the northern tundra in soils occupying in watersheds automorphic (podburs, gleyzems) and semi- hydromorphic (peat-gleyzems) position of the relief, the content of As, Zn, Ni, Pb, Cu increases. In peat soils of wetland systems, occupying low relief (depressions) and in the alluvial soils of river valleys the declining tendency is noted, with the exception of zinc which content in floodplain soils of the northern tundra is higher than in similar soils of the southern tundra. For cadmium practically a 2-3 fold increase of its content in all the soil types of the northern tundra compared to the southern one is revealed.The data obtained can be used for ecological monitoring in the areas of development and production of hydrocarbons and the assessment of anthropogenic impact on the natural environment of the Bolshezemelskaya tundra.