Spatial distributions of metal(loid)s and their transport in agricultural soils around abandoned metal mine sites in South Korea

Abstract

To develop efficient strategies and methods to remediate soils contaminated by metal(loid)s, it is vital to monitor the metal(loid)s in the soil by conducting field surveys and properly understanding their transport and spatial distribution characteristics. The present study aimed to elucidate the distinctive spatial distribution of anthropogenic arsenic (As) and metals from abandoned metal mine sites (AMMSs) to the surrounding agricultural soils. In order to investigate transport and spatial distribution of the metal(loid)s from mine tailing dumps to the surrounding agricultural soils, extensive field surveys were conducted across agricultural fields located in the vicinity of five AMMSs, i.e., Gubong, Nakdong, Daema, Angang, and Sunyang mines. A total of 2371 soil samples were collected from the study sites during 2010–2014. The total concentration of metal(loid)s, i.e., As, lead (Pb), and zinc (Zn), in the soil samples was measured. Horizontal dispersion characteristics of As and metals transported from the AMMSs to the surrounding agricultural soils were analyzed using the spatial data and geoaccumulation index. Furthermore, the distribution of anthropogenic metal(loid)s was also mapped to analyze their distinct spatial distribution using a GIS tool. Hot spots were formed within a 1-km radius of tailing dumps where anthropogenic As, Pb, and Zn in agricultural soils were highly concentrated. Among the anthropogenic metal(loid)s, As could be dispersed and distributed in a much wider region from the tailing dumps due to the high mobility of As through reductive processes in flooded paddy soils compared with other metals (Pb and Zn) whose transport and distribution are controlled primarily by the erosion process of mine tailing dumps (wind and water driven). The dispersion behavior of As has a relatively farther-reaching effect on agricultural soils due to its geochemical behavior in flooded paddy fields, which differs in magnitude from metals such as Pb and Zn. Therefore, the dispersion behavior of As should be focused on during the investigation, remediation, and management activities for agricultural soils contaminated by anthropogenic As and metals due to AMMSs.