Soil contamination in the zone affected by waste products of Tin Ore Processing in the Khabarovsk region

The degree of soil contamination in the impact zone of the Solnechnyi Tin Ore Processing Plant in the Solnechnyi district of the Khabarovsk region was evaluated. It was shown that the air contamination by the waste products of the ore-processing plant is extremely high with respect to the concentrations of toxic dust and heavy metals. The maximum concentrations of these contaminants exceed the background values by 16–80 times. The bulk contents of Pb, Zn, Cu, As, and Hg in the upper soil horizons within the impact zone exceeded the maximum permissible concentrations and the background values by 2–90 times. Abnormally high concentrations of Zn, As, and Pb were observed not only in the surface 10–cm-thick soil layer but also in the underlying (10–20 cm) horizon. The soil contamination transformed the geochemical sequence of heavy metals typical of the background soils (Zn > Pb > As > Cu > Hg) into a new sequence (As > Pb > Cu > Zn > Hg). The statistical data proved that the intensity of the migration of the heavy metals in the soils decreases with a rise in the soil humus content and a drop in the soil acidity. This should be taken into account in the elaboration of soil-protective measures in the investigated region.