Lead and stable lead isotopes as tracers of soil pollution and human health risk assessment in former industrial cities of Hungary

Abstract

Lead is a toxic heavy metal that has become much more prevalent in the environment since industrialization and causes considerable health problems. The current study investigated the spatial distribution and sources of lead from urban soils in former heavy industrial cities, Salgótarján and Ózd (northeastern Hungary). Even today, industrial byproduct (e.g., coal ash, smelter slag) dumps in both cities pose a real threat to the residents. Our analytical results acquired on samples from kindergartens, playgrounds, parks, roadside, etc. indicated a heterogeneous lead distribution with 8.5–1692 mg kg-1 for Salgótarján and 6.6–1674 mg kg-1 for Ózd. The enrichment of Pb results from the high variability of the potential anthropogenic contamination sources, such as iron and steel work, coal mines, coal-fired power plant, smelter slag, vehicle emission, etc., in the studied areas. The potential lead emission sources were defined by 206Pb/207Pb – 208Pb/207Pb and 206Pb/204Pb – 208Pb/204Pb isotopic ratios in urban soil samples and the local endmembers: namely brown forest soil (206Pb/207Pb: 1.20 in Salgótarján and 1.21 in Ózd), brown coal (206Pb/207Pb: 1.18 in Salgótarján and 1.26 in Ózd), and industrial byproducts (206Pb/207Pb: 1.18 coal ash in Salgótarján and 1.12–1.16 smelter slags in Ózd). A positive correlation between TOC, TN, Mn, and Pb in Salgótarján and between Fe, Mn, and Pb in Ózd, shows that the urban soil characteristics play a significant role in Pb distribution in the sampling sites. Our study confirms that coal ash in Salgótarján and smelter slag in Ózd can be considered primary anthropogenic Pb contamination sources, resulting in low chronic health risks for residents.