[Characteristics of Soil Physicochemical Properties and Enzyme Activities over Different Reclaimed Years in a Copper Tailings Dam].

Mining for metal and mineral resources lead to the rapid rise of tailings dams and caused serious damage to the ecological environment of the mining area. Soil physicochemical characteristics and enzyme activities were important indexes for ecosystem functions, and they were also important factors in evaluating soil restoration qualities. We selected nine sub-dams of the Eighteen River copper tailings in Yuanqu County, and analyzed the relationship between soil physicochemical properties and soil enzyme activities. The results showed that there were great differences in soil physicochemical properties over different reclaimed years, and as the reclaimed years passed, soil nutrient contents significantly increased. There were significant negative correlations between catalase and the ratio of soil carbon and nitrogen, and urease was positively correlated to total nitrogen and soil moisture. Phosphatase and sucrose demonstrated no significant relationships with soil physicochemical factors. Copper content gradually accumulated in soil as the restoration period of sub-dams increased. Arsenic and cadmium content increased initially and then decreased before they gradually reached a stable level. In addition, there was no significant difference in zinc content among different sub-dams. Together, these results provide the ecological basis for further studies in soil ecosystem restoration and degradation mechanisms in copper tailings.