Effects of mining on the potentially toxic elements in the surrounding soils in China: A meta-analysis

Previous studies about the effects of mining on the potentially toxic elements (PTEs) in the surrounding soils mainly focused on single or few mining areas. However, these studies couldn't comprehensively quantify the mining-induced variations of soil PTE concentrations at the national scale. Moreover, the quantitative relationships between the effects of mining on soil PTEs and some related factors remained unclear at the national scale. This study first conducted a literature survey for soil PTE data affected by mining in China. Then, the random-effects model in the meta-analysis was used to quantify mining-induced variations of soil PTE concentrations in the surrounding areas. Last, the single meta-regression was used to explore the relationships between the effects of mining on soil PTEs and the related factors at the national scale. Results showed that: (i) mining-induced increases of soil PTE concentrations followed the order: Cd (1017%) > Hg (319%) > Pb (291%) > Zn (176%) > Cu (129%) > As (92%) > Ni (23%); (ii) mining-induced increases of soil PTE concentrations in clay (531%), non-ferrous mine (188%), paddy field (212%), and Central South China (290%) were more than those in other soil textures, mine types, land-use types, and geographical divisions, respectively; (iii) the effects of mining on soil PTEs were negatively correlated with soil pH (Q_M = 29.76, p < 0.01) and positively correlated with soil organic carbon (Q_M = 28.54, p < 0.01) and mean annual precipitation (Q_M = 91.75, p < 0.01); (iv) the effects of mining overall decreased with the sampling year (Q_M = 35.01, p < 0.01) and showed latitudinal zonality (Q_M = 180.39, p < 0.01). The above results provided valuable information for soil PTE mitigation in the areas affected by mining in China.