粤北大宝山矿尾矿铅污染迁移及生态系统环境响应

Transfer and Ecosystem Effects of Lead Contamination in Dabaoshan Mine Tailings,Northern Guangdong

粤北大宝山铁多金属矿床的开发给环境带来了严重的危害。采选冶产生的废液及固体废弃物堆积的淋滤酸水,携带浸滤出的大量重金属离子随着酸水排入下游河道,严重影响矿区及酸水流域的生态环境。将矿床—土壤(含河流底泥)—水体—生命体视为统一的生态环境系统,从尾砂、水体、河流底泥、土壤以及食用蔬菜等方面探讨整个环境系统对重金属Pb的环境响应。结果表明:河流水中高Pb含量直接源于尾砂,并受水体pH值的显著影响;河流底泥能够大量聚集水体中的Pb,在高pH值时,相对稳定存在,在水体pH值降低时,Pb会被再次从河流底泥中释放出来,形成河流二次污染;土壤中Pb含量受土壤pH值和土壤粒度的影响;食用蔬菜中Pb的高含量受土壤Pb高含量决定,并受土壤pH值的影响,通过改善农业灌溉水质,提高土壤pH值,可以降低蔬菜重金属Pb含量。

Mining activities have caused severe soil environment changes in Dabaoshan Mine, Guangdong, Southern China. The acid mine drainage and heavy metal ions drained directly into the Hengshihe river, which contaminated severely the ecological environment along the river. The tailings, soils, sludges, water and plants are regarded as whole ecosystem, the environmental responses of whole ecosystem to acid mine drainage and heavy metal ions are investigated. The lead in river water came from the tailings, and the lead concentration is affected distinctly by the pH value of water. River sludges can accumulate stably lead of water in high pH value water, but it should be released from the deposits when the pH value of water is low, forming the secondary contamination. The lead concentration in soils is affected by pH value and granularity of soils. The high lead concentration in plants is related with the total lead in soils, and is affected by the pH value of soils, thus increasing soils＇ pH value can reduce lead concentration in plants by improving irrigation water quality.