Assessment of the risk of pollution by sulfur compounds and heavy metals in soils located in the proximity of a disused for 20 years sulfur mine (SE Poland)

The study assessed the long-term effects of anthropogenic pressure of the sulfur industry on turf-covered soils located in the vicinity of the sulfur mine Grzybów. The study assumes that 20 years which elapsed since the end of the exploitation of sulfur is a period sufficiently long for the content of sulfur compounds in soils not to exceed the permissible level and that soil of the region can be classified as not contaminated. A part of the study involved identification of changes in the contents Stot. and SSO42− in soils collected in the 1970s and early twenty-first century. It was also traced the relationship between the content of sulfur compounds and selected soil properties and estimated risk of soil environment pollution by heavy metals. Mean contents of trace elements studied amounted to 10.2–10.8 mg kg−1 for Pb, 14.3–39.4 mg kg−1 for Zn, 0.2–0.4 mg kg−1 for Cd, 3.8–32.2 mg kg−1 for Cr, 2.7–15.1 mg kg−1 for Cu and 2.9–18.7 mg kg−1 for Ni. Based on the results of SSO42− content in soils collected at a distance of 1 km from the mine, it was found out that despite the passage of years, the amount of this type of sulfur still is increased and exceeds 0.14 g kg−1. As the distance from the mine grew lower (from 0.017 to 0.03 g kg−1) average content of the sulfur form was observed. In the studied soil material we found generally positive, strong correlation between the Stot. and SSO42− content and analyzed trace elements. The degree of contamination of examined soils with heavy metals was estimated on the basis of the integrated pollution index, which pointed to a moderate and low level of antropogenization of this area. In addition, the relationship between the determined characteristics of soils (Corg. contents, the fraction <0.002 mm and pH) and heavy metals confirms that the trace elements present in soils do not occur in mobile forms in the soil solution.