新疆某地浸采铀矿山退役井场地下水污染特征

地浸采铀对地下水的污染及退役后地下水的复原是铀矿冶工业中的一个重要环境问题.本文对某退役地浸井场地下水的污染状况进行了系统的监测与分析.地浸生产对矿层上部和下部的含水层没有影响，各项指标处于该区地下水的本底范围内，也符合Ⅲ类地下水水质标准.地浸对采区内含矿含水层地下水造成严重的污染，污染组分主要有SO2_4、NO3_、H＋、U、Ca、Mg、Ba、Fe、Cu、Zn、Pb、Mn、Cd、As、Ni、F等，污染物的来源包括地浸生产中加入的化学试剂和岩石、矿物中的各种常量元素、微量元素被浸出释放进入地下水中.污染范围主要分布在地浸采区内，对采区上游地下水的污染影响较小；对采区下游地下水的污染程度较高，污染范围已达到采区下游700~1000 m.退役后天然地下水流场的恢复导致污染晕圈向井场下游迁移，但是由于岩石的“自然净化”作用导致污染物浓度随水流方向显著降低.

The Characteristics of Groundwater Contamination of a DecommissionedWellfield in Some in Situ Leaching Uranium Mine,Xinjiang,China

Groundwater contamination from in situ leaching of uranium mining and groundw_ater restoration after decommissioned is an important environmental problem for uranium mining industry. Systematic monitoring and analysis for groundwater contamination of a de_commissioned in situ leaching wellfield was carried out. The in situ leaching production had not affected on the upper and lower aquifer which all indexes are within background of groundwater of this area and also accord with the ClassⅢgroundwater quality standards. The in situ leaching brought in serious contamination for groundwater in wellfield. The contami_nants mainly are SO2_4 ,NO3_,H＋,U,Ca,Mg,Ba,Fe,Cu,Zn,Pb,Mn,Cd,As,Ni,F,and so on. These contaminations come from both chemical reagents added during production period and a variety of major and trace elements leached and released into groundwater from rocks and minerals. The contaminated areas are mainly within wellfield. The contamination of up_stream groundwater is less. The downstream groundwater was contaminated and the contami_nated water halo had spreaded to 700~1 000 m to downstream. The restoration of natural groundwater flow field after decommissioned caused the contaminated water halo to move a_way from wellfield to downstream, but the concentration of contaminants decreased significantly in the groundwater flow direction due to the natural purification of rocks.