Soil Pollution Characteristics and Ecological Risk Assessment of As at a Large-scale Arsenic Slag-contaminated Site

Abstract

A large-scale arsenic slag-contaminated site was selected to determine soil pollution characteristics and the degree of ecological risk of a large-scale contaminated site. In this study, 184 site soil samples, 101 agricultural soil samples, and 14 arsenic slag samples were collected and the pollution characteristics and ecological risk of As were evaluated using multivariate statistics, geostatistics, and the geoaccumulation and potential ecological risk index methods. The results show that the average As contents in site soil, agricultural soil, and arsenic slag are 1333.0, 358.1, and 17316.1 mg·kg-1, respectively. The degree of contamination of As exceeds the national standard Ⅲof the environmental soil quality. The results of the vertical and three-dimensional distributions of contamination show that As is accumulated to different extents in different strata. The accumulation in the site surface soil is the most serious. The As concentrations in site soil samples are higher than that in agricultural soil samples. The potential ecological risk index method shows that all mean potential ecological risk indexes exceed 100 in different strata. Moreover, the percentage of samples in site and agricultural soils at medium pollution level ratios is 58.21% and 61.39%, respectively, illustrating that the As pollution of soil samples from this contaminated site and surrounding farm areas is serious.