Accumulation of Cd and Its Risks in the Soils of the Xijiang River Drainage Basin in Guangxi

Abstract

To understand the distribution and risk of soil cadmium (Cd) in the Xijiang River drainage basin in Guangxi, a total of 2512 soil samples were collected nonferrous metal mining area, farmland (paddy soils and dryland soils) and the background soils, in the Xijiang River drainage basin in Guangxi.The results showed that Cd concentration was 0.514 mg·kg-1 in background soils significantly higher than previously resulted(0.148 mg·kg-1)and that in Guangxi background soil(0.267 mg·kg-1). The geometric average concentration of Cd in dryland soils, paddysoils and mining soils was 0.559, 0.787, 5.71 mg·kg-1, respectively, which were significantly higher than background soils. The Cd concentration exceeded the background soils and baseline by 51.2% and 35.2% in dryland soil, 66.7% and 39.6% in paddy soil, 77.8% and 71.4% in mining soil, high Cd concentration occurred in the Nandan County, Dahua County, Duan County, Huanjiang County and Yizhou City, as well as Liujiang County, These regions have developed severe and even extremely serious pollution, medium-high pollution accumulation and higher-extremely high potential ecological risks. The Cd-pollution in soils in agricultural and mining soils in upstream of Xijiang River in Guangxi is serious, due to mining activities and high Cd geological background. People in the mining area and surrounding areas who live on local crops, vegetables, may expose to the Cd-pollution. It is recommended to further develop a Cd risk assessment through a soil-plant-human system, taking appropriate measures to control risk.