Source apportionment and probabilistic risk assessment of heavy metals in selenium-rich soils in Hainan Province, China

Abstract

Heavy metal (HM) contamination severely restricts the safe utilization of selenium (Se)-rich soil. Based on 10 HMs in 3933 topsoil samples from Se-rich soils in Hainan Province, we used the enrichment factor (EF) to evaluate the pollution level of soil HMs; moreover, the positive matrix factorization (PMF), multivariate statistical analysis, and geostatistics were utilized to quantify the sources of soil HMs; and potential ecological risk index (RI) and human health risk (HHR) of different sources from five land use types were quantifiably determined via combined HM sources with RI and HHR assessment models. The evaluation results of EF showed that the Se-rich soils were moderate enrichment of Hg and Sb, but they were still characterized by lower content compared to other regions of the world. And four sources were quantitatively identified as natural sources (40.8 %), industrial sources (22.3 %), agricultural sources (23.6 %), and atmospheric sources (13.3 %). For RI, the atmospheric source was the main anthropogenic contributor to plowland, urban land, woodland, and unused land with 24 %, 30 %, 25 %, and 26 %, respectively, and Hg was the most dangerous element. But the contribution of industrial sources (25 %) to RI in the garden-land was higher than that of atmospheric sources (23 %). In terms of HHR, industrial sources were the primary anthropogenic contributors. Children were exposed to slight health risks, with Cr, As and Pb being the major contributors, and the cumulative probability of non-cancer and cancer risks for children was 14.93 % and 25.29 %, respectively. The cancer risk for children in garden-land (1.2E-04) and plowland (1.3E-04) exceeded the threshold (1.0E-04), which requires attention. Both non-cancer and cancer risks for adults were all at acceptable levels, with only a 15.89 % cumulative probability of cancer risk. Overall, the health risks of children were clearly higher than those of adults, and plowland and garden-land were at higher HMs risk than other land use types. The HMs risks in the study area were profoundly affected by the basalt, while the input of HMs from anthropogenic activities should be prioritized for the control of industrial activities.