Mining impacts on trace metal content of water, soil, and stream sediments in the Hei River basin, China

The impacts of mining to watersheds are highly variable depending on the type of mining, processing of ores, and environmental factors. This study examined the Hei River in central China, for impacts of gold and iron mining on concentrations of metals in river water, river sediments and stream-channel soils. No production processing of ores occurs on-site at either mine. Total metal content and extractable metals using DTPA were determined. Total concentrations of Cd, Cu, Pb and Zn were high in some stream sediments and soils near the mine sites; metal concentrations ranged from 4-24, 11-100, 11-380, and 33-1600 mug g(-1) for Cd, Cu, Pb, and Zn, respectively, in soil. Total cadmium was high in all soils and sediments. Extractable metals were low, with the exception of Pb and Cu. At the gold mine, extractable Pb ranged from 8 to 33%; extractable Cu ranged from 3 to 21% of total metal concentration. Chromium and Ni were not above typical concentrations in either soils or river sediments. An abundance of carbonates, high river water pH, and high water flow rates all appear to contribute to limiting quantities of metals in the river water. If mining activities are not changed, impacts of mining on downstream metal concentrations in river water should be nominal.