| Taking a typical lead-zinc mining area watershed in northern Guangxi as the research object, the total amount and morphology of nine heavy metals(Zn, Pb, Cd, Fe, Mn, Cu, Cr, Sb, and As) and fine soil property indicators(pH, conductivity, cation exchange, organic matter, and particle size) in the surface soils of the Yangshuo lead-zinc mine were analyzed and determined. The accumulation and distribution of soil heavy metals and their main controlling factors were revealed using correlation, redundancy(RDA), and GeoDetector analyses. In the analytical data of soil samples, the mean values of As, Cd, Fe, Cu, Mn, Pb, and Zn exceeded the background values, in which Cd, Mn, Pb, and Zn were 4.01, 3.15, 5.53, and 9.72 times higher than the background values, respectively, indicating that they were significantly enriched in the surface soil. There were more noticeable spatial differences in distribution, which were higher in the alluvial floodplain accumulation area(1-6) than those in the other areas(7-9). The available states(K) of Pb and Mn were 48.8% and 57.2%, respectively, with high bioavailability and average potential migration capacity(PMI 0.015-0.068 and 0.036-0.082, respectively). The Zn and Cu had some bioavailability degree, with available states(K) of 30.9% and 16.8% and moderately available states of 10.9% and 13.6%, respectively. The difference was that Zn had a strong migration capacity(PMI 0.160-0.203), and Cu had an average potential migration capacity(PMI 0.017-0.084). Fe and Cr had a difficult-to-use state(N)>95%, low bioavailability, and weak migration capacity(PMI<0.005). The results of the analysis of the main controlling factors affecting accumulation and distribution showed that Cr was controlled by cation exchange capacity(CEC) and clay; Fe was controlled by sand; As was controlled by electrical conductivity(EC) and pH; Cu, Zn, Cd, and Sb were controlled by pH and clay; Pb accumulation was controlled by pH and soil organic matter(SOM); Mn was controlled by pH. This study quantified the main controlling factors affecting the accumulation and distribution of soil heavy metals, which can provide a scientific basis for decision making in the prevention and control of soil heavy metal pollution. |
