Significance of Delayed Geochemical Hazard of Cd in Dawu River Domain in the Dexing Copper Mine, Jiangxi Province

The smelting factory of Dexing Copper Mine is separated, so mine stripping material and low grade ore yards have huge impact on the environment. For a variety of reasons, the efficiency of operation of the environmental protection facilities in Dexing Copper Mine area was so low that all the acid wastewater was not treated well before discharge. This can lead to a problem that extracting copper and other metal mineral from the low grade ore in the waste stone, and also produce acidic wastewater and heavy metal pollution. Finally, the wastewater discharge into the Dawu River has made huge impact on water, soil, ecological environment. Based on the mathematical model of DGH, this paper analyzed the soil samples of Dexing Copper Mine in the Dawu River domain by the method of successive extraction. The results reveals the DGH characteristics of Cd element in the soil of downstream Dawu River. Cd element in the soil of downstream of Dawu Rive tends to shift from TRCP-Cd (total releasable content of Cd element) to TCAS-Cd (total concentration of active species of Cd element). The critical point of outbreak is TRCP=185.90 ng/g. 36% of the samples of downstream Dawu River oversteps the critical point of outbreak, making it possible to break out. Meanwhile, the analysis of DGH of Cd element is of great significance to early-warning of soil heavy metal pollution and improvement of ecological environment in the study area.