Environmental risk related to presence and mobility of As, Cd and Tl in soils in the vicinity of a metallurgical plant - Long-term observations

Analysis of the content of As, Cd and Tl accompanying Zn-Pb ores was performed using soil material sampled around the zinc-works in Miasteczko Slaskie. It was found that the total content of As, Cd and Tl was considerably higher than the values recorded at the same sites 20 years earlier. This clearly confirms considerable pollution of the environment which continues despite pro-ecological actions taken by the zinc-works. The analysis of the spatial distribution of pollution revealed that the zinc-works itself is no longer the main source of contamination as was the case in 1998. Instead, in 2018 the main sources of As, Cd and Tl emissions were the erosion and deflation processes in old, unprotected mining and industrial waste dumps located near the zinc-works. The most polluted soil layers are the top layers in the soil profile. The content of As, Cd and Tl determined in them was 10 times greater than in the deep layers. There was also a positive change in environmental conditions, which occurred over the preceding 20 years, namely an increase in the content of sparingly soluble fractions, fractions bound with organic matter, and residual fractions. It was also found that depending on the geochemical background and readily mobile fraction values used in the calculations, there is still very high contamination and very high ecological risk with respect to As, Cd and Tl after 20 years. However, when using the quantity of phytoavailable elements as well as the quantity of cations on ion exchange positions and bound to carbonates to calculate the risk assessment code, the analysis showed that environmental conditions improved. (C) 2019 Elsevier Ltd. All rights reserved.