Assessment of Soil-Water Composition Dynamics in the North Taiga Forests upon the Reduction of Industrial Air Pollution by Emissions of a Copper—Nickel Smelter

This work is aimed at assessing the dynamics of the composition of soil waters in coniferous forests subjected to air pollution from the Severonikel’ copper-nickel smelter in Murmansk oblast. The objects of investigations are the most common in boreal zone spruce forests with dwarf shrubs + green mosses and pine forests with dwarf shrubs + lichens. The results show a significant intra- (below the crowns and between the crowns) and interbiogeocenotic (spruce and pine forests) variation in the composition of atmospheric deposition and soil waters in forests under pollution. The atmospheric deposition of pollutants and leaching of their compounds from all soil genetic horizons are tens (sulfates) and hundreds (copper and nickel) times higher than in reference sites and their fluxes below the crowns are usually more intense than between the crowns. Long-term dynamics (from 1993 to 2012) demonstrate reliable trends in the reduction of concentrations and leaching of sulfates and heavy metals from the soil. The molar ratio of basic cations to aluminum (BC/Al) in soil waters from all soil horizons does not drop to the level of critical, whereas for mineral nitrogen the lowest critical level (0.2 mg/L) was exceeded in waters from all horizons at all stages of digression. It was shown that, for the early detection of exceedances of the critical level for mineral nitrogen in soil waters, an evaluation of their composition is necessary not only between the crowns, but also below them.