The distribution and coupling relationship of heavy metal content in water and sediments in the gold mining area

The relationship of the content of heavy metals between water and sediments in a river plays a significant role in river pollution prevention and control. Based on investigation and analysis of the heavy metal concentrations in three types of river, the authors studied the spatial distribution of the concentrations of heavy metals in the water and sediments and the adsorption isotherm models of their flowing through different lithologies as well as the degree of pollution, with the purpose of establishing heavy metal content coupling relationship between them in gold mine rivers. The results show that lots of heavy metal elements in all the four rivers have exceeded the national standard limit values. Seven kinds of heavy metals in river water have surpassed the set standard, in which the surpassing situation of chromium and arsenic is not serious. In sediments, mainly Hg, Pb, Cd, Cu and Zn have surpassed the set standard, of which the most serious element is Hg, whose highest concentrations in water and sediments have respectively reached 3099 times and 244 times that of the set standards. The main mode of occurrence of heavy metals in the river is the deposition state, and adsorption-desorption of sediments is the main control factors of heavy metals pattern in river sediments and water in the stream. Viewed from adsorption-desorption equilibrium, the heavy metals in the river and the stream sediments are consistent well with the Langmuir isotherm. Different mining activities and lithologies will affect the heavy metal average maximum adsorption capacity of the sediments. The average adsorption capacity is maximum in the Shuangqiao River passing through the loess region. This conclusion provides the reference basis for the environment pollution prevention and early warning in the mining area.