Combined approach for assessing metal(loid)s leaching, mobility and accumulation in a specific near-neutral (pH) environment of a former Cu-smelting area in the Old Copper Basin, Poland

Abstract

Topsoils, soil profiles, water, and stream sediments as well as slags and rocks were analyzed to assess the extent and severity of environmental pollution resulting from historical Cu mining and smelting in the vicinity of Leszczyna, Old Copper Basin, SW Poland. Numerous tailings, smelting wastes, and Cu-rich rocks were disposed in the study area, causing long-term leaching and accumulation of various metal(loid)s. Surrounding the anthropogenically impacted area, two types of geochemical background are distinguished, one of which is associated with rocks and soils that are naturally enriched in metal(loid)s and the second one is free of them. The presence of significant anthropogenic changes combined with natural enrichment creates a highly complex environmental situation with regard to different sources of metal(loid)s. Additionally, the ore-hosting carbonate rocks are responsible for specific near-neutral (pH) conditions. With a focus on numerous elements (Cu, Zn, Pb, Ni, As, Cd, Co, Ba, and Cr) we studied spatial and vertical metal(loid)s distributions in soils to determine elements fate under near-neutral conditions. We applied the Synthetic Precipitation Leaching Procedure (SPLP) to evaluate the leaching potential of geogenic and anthropogenic materials and the Acid Neutralization Potential (ANP) test to measure the impact of slags on the pH of local soils. The EDTA extraction indicated high (bio)availability of Cu, Cd, Pb, and Zn, and suggested that metals from Cu-rich rocks are substantially more mobile than these of metallurgical origin. Our data indicate significant metal(loid)s mobility from surface-deposited wastes, especially into soils and stream sediments. The study proves that in the near-neutral conditions wastes are mainly subjected to short-time, rainfall-associated leaching, which is responsible for mobilization of labile metal(loid)s fractions (especially Cu, Pb, Zn, and Cd).