Spatial Distribution Study and Pollution Assessment of Pb in Soils in the Xijiang River Drainage of Guangxi

Abstract

To obtain data for the accumulation of Pb and its risk in soils in the Xijiang River drainage of Guangxi, 2594 samples were collected from nonferrous metal mining soils, farmland soils (paddy soils and dryland soils), and the background soils in the drainage area. Geostatistical analysis combined with GIS was used to study the soil spatial distribution characteristics and pollution distribution of the soil Pb content. The results showed that the Pb background value of the soil was 51.84 mg ·kg-1 in the Xijiang River Basin, and the results of the single sample T test showed that the soil background value was significantly higher than that of a previous study (22.08 mg ·kg-1) and the soil background value (20.50 mg ·kg-1) in Guangxi province. The geometric mean concentration of Pb in the mining soils, dryland soils, and paddy soils were 655.9, 116.7, and 40.63mg ·kg-1, respectively, significantly higher than that in other soils. Using GB 15618-1995 and the baseline as the limiting value, the corresponding exceedance rate of the mining soils, dryland soils, and paddy soils were 57.69%, 16.40%, and 8.92% and 54.95%, 8.09%, and 2.03%. The mining soils and farmland soils had an obvious lead accumulation trend. There was an obvious spatial autocorrelation of Pb in the soil, and the structural variation was dominant. The content of Pb in the upper reaches of the Xijiang River reached the middle and lower reaches of the Xijiang River, and the soil Pb was characterized by an obvious decrease. The accumulation of high Pb content in the upper reaches of Diaojiang River is much larger than that in the lower reaches of Diaojiang River. The content of Pb in soil samples in the Xijiang River Basin was mainly rated between mild pollution and moderate pollution, and the pollution was concentrated in the municipal administrative area and the mining activity area. The pollution of the soil in Jinchengjiang and Nandan counties was closely related to the frequent local mining activities.