Spatial distribution and sources of seven available heavy metals in the paddy soil of red region in Hunan Province of China

In recent years, the soil ecosystem in China has been increasingly polluted by heavy metals. As such, this paper investigated the pollution degree and spatial distribution of available heavy metals and determined their sources in the paddy soil of red region in Hunan Province of China. A total of 80 topsoil samples were collected (0-20cm) from the study area, and their spatial distribution and sources were analyzed using geostatistical and multivariate analysis. The results showed that the contents of available Cu, Zn, Ni, Cr, Cd, As, and Pb in the soil were 1.652, 1.057, 0.304, 0.747, 0.139, 0.295, and 6.348mg/kg, respectively. Compared to soil background reference contents, all tested available elements exceeded the reference value except Ni and Pb. The spatial variation of available heavy metals was visualized by GIS. Correlation analysis was used to determine the association between soil properties and available heavy metals. The multivariate analysis suggested that the source contributions of the natural source, agricultural sources, and industrial activities accounted for 31.78%, 27.90%, and 15.48%, respectively.