大宝山矿水外排的环境影响:Ⅱ.农业生态系统

Environmental impacts of acid mine drainage from the Dabaoshan Mine: Ⅱ. Agricultural ecosystem

大宝山外排酸性矿水对周边农村地区农业生态系统具严重的负面影响,表现在:农田所用的灌溉水酸度很强,灌溉水中多种重金属含量高于国家农田灌溉水质标准,其中Cd超标约16倍;土壤严重酸化,pH值可低至3.9,总实际酸度平均达47mmol/kg,比水溶性酸度高147倍,表明由矿水带进土壤的无机酸通过土壤的缓冲作用暂时转化为非水溶态并在土壤中累积;土壤重金属含量超标,以Zn、Cu和Cd为甚;粮食和果蔬等作物重金属污染严重,其中尤以Cd最为突出,最高可超标近150倍。

Acid mine drainage has had severely adverse impacts on the downstream agricultural ecosystem. The irrigation water was highly acidic with pH about 3.2, accompanied by high concentrations of various heavy metals, which has acidified and contaminated the soils. The pH of the soils could be as low as 3.9. However, most of the mineral acids introduced into the soils by irrigation were transformed to insoluble forms through acid buffering processes and temporarily stored in the soils. The concentrations of heavy metals in the soils exceeded the national standards (China), particularly for Zn, Cu and Cd. Consequently, crops grown in these soils were highly contaminated by heavy metals with the concentration of Cd in some edible portion of the crops being nearly 150 times as high as the national standards (China).