Assessment and monitoring of soil and plant contamination with trace elements around Europe's largest copper ore tailings impoundment

Abstract

Europe's largest copper ore tailings impoundment has been considered a potential source of risk for human health, thus leading to the elimination of agricultural production in the surrounding area and its subsequent afforestation. The aim of this study was to analyse the level, spatial distribution and temporal changes in soil and edible plant contamination with trace elements around the impoundment, taking into account the local soil properties. The mean concentrations of Zn, Pb and As (31.5, 19.3 and 3.9 mg kg^-1, respectively) were found to be higher than median values in soils of Poland, but they do not indicate soil pollution or enrichment when assessed using the relative geochemical index (I_geo) and enrichment factor (EF). The Cu concentration (mean 25.6 mg kg^-1) was significantly higher than the median value for Polish soils, indicating moderate to high pollution/enrichment. A relationship between Cu concentration in topsoil and distance to the impoundment, in particular in its eastern forefield, indicates that this landfill site may be considered the source of soil contamination with Cu. However, both the mean and maximum concentrations of all elements under study, including Cu, were below the legal intervention levels. Long-term topsoil monitoring, although high data variability on permanent plots, has documented stable concentration or slow decrease of element concentration over a period 1995-2016. Cu and Zn concentrations in vegetables from home gardens do not differ from typical values in commercially available products, whereas higher than typical concentrations of Pb and As may result from other local sources of contamination. Low level and stable soil and plant contamination with trace metals justifies continuation of crop production and no need for the further conversion of arable lands into forests. The relatively little negative impact of the tailings impoundment, despite its large dimensions, results probably from implemented effective anti-emission measures.

Keywords: Copper mining; Crop quality; Enrichment factor; Geochemical index; Heavy metals; Soil degradation.