华南地区含硫化物金属矿山生态环境中的重金属元素地球化学迁移模型--重点对粤北大宝山铁铜多金属矿山的观察

Geochemical migration model of heavy metallic elements in eco-environmental system of sulfide-bearing metallic mines in South China——with specific discussion on Dabaoshan Fe-Cu-polymetallic mine,Guangdong Province.

粤北大宝山是华南金属成矿带的大型铁铜、铅、锌、钼等多金属综合性矿床,富含硫化物,位于北江支流横石河的上游分水岭,流域封闭性很好。矿山开发引起横石河下游的上坝村成为远近闻名的"癌症"村,部分村民出现"痛痛病"疑似症状。由于其特殊的地理位置和对下游引发的严重污染,该矿山成为研究湿热地区含硫化物金属矿山重金属元素生态-环境地球化学迁移的理想场所。以Zn为例,该矿山重金属元素从矿体中向生物体迁移过程经过尾砂/水反应界面、水/沉积物反应界面、土壤/间隙水溶液界面和土壤/植物界面4个重要的反应界面。其中,尾砂/水反应界面控制重金属从源头尾砂中的释放;水/沉积物反应界面控制重金属在水体中与河流沉积物的沉淀与释放的平衡;土壤/间隙水溶液界面控制土壤生物有效性;土壤/植物界面控制生物对重金属的吸收与利用。4个界面的介质间相互作用较好地刻画大宝山矿山因为开采,重金属元素从内生环境中曝露出来,然后在表生环境中释放、迁移、转化、归宿的迁移模式。上述认识对矿山重金属污染治理具有重要的指导意义。通过改变重金属迁移反应界面的条件,可以阻断矿山元素的迁移,达到污染治理的目的。

The Dabaoshan Mine is a sulfide-bearing type of Fe-Cu-Pb-Zn-Mo polymetallic deposit in the famous South China metallic deposit belt. It is specifically typical in eco-environmental effects of sulfide mine and mining activities in warm and humid area, and is responsible for the presence of the ＂cancer village＂ at Shangbacun which is situated in the lower reaches of the mine. Some villagers have suspicious symptom of ＂Itai-Itai disease＂. Because of this, the mine attracted much attention of researchers in the field of environmental geochemistry of wanes and mining, and the ecological and geochemical migration model of heavy metals was included among the hot topics of discussion. It is shown that there exist four important reaction interfaces, the tailings/ water, the water/sediments, the soils/pore water and the soils/plant interface, in releasing and migration of heavy metal elements from mining railings to destination ecological system, as exampled by element Zn. The tailings/water interface controls the releasing of heavy metals from main source of railings. The water/sediments interface governs the equilibrium of precipitation and releasing of heavy metallic elements between water and sediments. The soils/pore water interface determines the bioavailability of the soils, while the soils/plant inteHace is responsible for the absorption and utilization of heavy metallic elements by living beings. The interaction of different media of the four reaction interfaces may be used to describe the geochemical migration model of heavy metallic elements, i. e. , the path chain first exposing to the surface from the deposit ores, and then releasing, transporting, transforming and end-resulting in surface environment. The migration of heavy metals from mining area makes heavy metals accumulate in areas neighboring the mine and in lower reaches of the mine, resulting in more and more ecological press. The heavy metals migrate to plants and animals through food chain and to human at last, and do harm to ecological safety and life health. The migration can be stopped or prevented through changing the environmental conditions of interfaces, which may help the treatment and prevention of environmental pollution of heavy metals.