Pollution characteristics and probabilistic human health risks of thallium and other heavy metals in soils from a typical copper mining city in the Yangtze river Delta, eastern China

Heavy metals contamination in soil from copper mine areas is a serious and widespread problem in China. In this study, the content of Tl, Hg, Cu, Cd, Ni, Pb and As and probabilistic human health risks were investigated in a typical copper mining city. Copper showed the highest average content of 184.29 mg/kg, followed by Pb, As, Ni, Tl, Cd and Hg. Approximately 54.2% of study sites were moderately contaminated by Cu, Cd, As and Tl. Among the heavy metals, Hg, Cu and Cd showed relatively high mobility and medium risk in the environment based on the chemical speciation. In particular, Tl was mainly present as Tl(I) in soil with more biovailability and solubility. Moreover, the probabilistic human health risk assessment using Monte-Carlo approach revealed that heavy metals in soil can cause non-carcinogenic risks (adults: 0.03%, children: 48.45%) and carcinogenic risks (adults: 41.79%; children 61.98%). The soil oral ingestion is the main exposure pathway for human exposed to heavy metals. Our findings indicate that the copper mining activities can cause high level of heavy metals in soils, and corresponding health risks. Meanwhile, these results could provide important information and theoretical support the development of precise soil pollution management strategies in copper mining areas.