Heavy metal(loid)s in agricultural soils in the world's largest barium-mining area: Pollution characteristics, source apportionment, and health risks using PMF model and Cd isotopes

Barium (Ba) mining and smelting activities release heavy metal(loid)s (HMs) that may cause threats to agro-ecological systems and human health. Here, contamination features, source apportionments, and associated health risks from agricultural soils were systematically investigated. According to descriptive statistics and HM single-pollutant indices, Ba, Cd, and As are priority control pollutants. Spatial interpolation and autocorrelation results indicate that Ba, Cd, and Zn have an aggregated distribution, clustered in the northwest of the study area in Guizhou Province, SW China. Pollution sources were apportioned based on multivariate statistics and a positive matrix factorization (PMF) model. As Cd is the dominant pollutant in Ba mines, Cd isotopic fingerprints and Bayesian isotopic mixing models in R were used to characterize the sources of Cd. PMF source apportionment and Bayesian isotopic mixing modeling indicate that the predominant sources of Cd in agricultural soils in Ba mining areas are mining and smelting, followed by agricultural activities and atmospheric deposition. PMF source apportionment suggests that the primary sources of HMs are Ba mining/smelting and agriculture, fol-lowed by sewage irrigation, and atmospheric deposition. Barium, As, and Cd pose the highest non-carcinogenic and carcinogenic risks, and should be prioritized for control.