河流沿岸土壤对上游矿山及矿山开发的环境地球化学响应——以广西刁江流域为例

刁江流域上游的矿山和矿山开发引发了显著的土壤环境地球化学变化,突出表现是沿岸形成了严重的土壤重金属污染带。污染带的分布与近20多年来的洪水淹没区和引水灌溉区呈现高度的一致性。上游地带的土壤污染区有明显的尾砂沉积,污染呈显性状态,而下游地带的尾砂沉积现象不明显,污染表现为隐性。无论是上游还是下游,土壤中的As、Pb、Zn、Cd含量均异常高。水田的犁底层对污染物质具有明显的隔断作用,而旱地淀积层中的污染物含量比较高,对污染物质的隔断作用不明显。污染耕地上生产的玉米中的Cd、Pb、Zn含量和大米中的Cd、Pb含量超过国家食品卫生标准。

Environmental geochemical response of soils along banks of a river to mines and mining activity in the upper reaches of the river-A case study of the Diaojiang River drainage system,Guangxi,China.

Mining activities in the upper reaches of the Diaojiang River have caused significant geochemical changes in soil environment,and especially they have formed a serious heavy metal pollution zone in soils along the Diaojiang River.The distribution of this polluted zone is quite consistent with the flooded area and irrigated area formed in past 20 years.There are distinct tailing sand deposits in the soil-polluted area in the upper reaches of the river and pollution is apparent,while the phenomenon of tailing sand deposition in the lower reaches is not apparent and pollution is hidden.Whether in the upper reaches or in the lower reaches,As,Pb,Zn and Cd contents in soils are relatively high.The plough sole of paddy land can obstruct the downward transport of heavy metals,while the illuvial horizon of dry land has a relatively high content of pollutants and its obstruction to pollutant transport is not pronounced.The concentrations of Cd,Pb and Zn in corn and Cd and Pb in rice in arable land exceed the national food standards and may have serious detriment to public health.