Metal(loid) Source Apportionment and Spatial Drivers in Irrigated Terrace Soils in a Typical Pb-Zn Mining Area

Metal(loid) contamination levels and the factors governing metal(loid) accumulation patterns in terraced agricultural systems were studied using 1250 surface (0-20 cm depth) soil samples. The average concentrations of Cr, Ni, Cu, As, Cd, Pb, and Zn were 132, 62.3, 140, 42.2, 33.8, 535, and 2384 mg kg^-1, respectively. Correlation analysis (CA) and positive matrix factorization (PMF) modeling were conducted to identify the sources of the metal(loid)s and the forest regression algorithm was used to elucidate the factors influencing their spatial differentiation. Cr and Ni originated mainly from natural soil-forming processes and As, Cd, Pb, and Zn originated from irrigation water. Cu, As, Cd, Pb, and Zn were controlled by source-related factors, and the distance to a residential area (Dis-RE) was the most significant covariate for these five elements. The results provide insights into the identification of the sources and clarification of the diffusion of metal(loid)s in similar mining regions.