广西某地金属冶炼废水外溢对农田土壤的污染特征

Pollution of Agricultural Soils by a Wastewater Outflow from a Metal Smelter in Guangxi Zhuang Autonomous Region

通过对冶炼厂附近受外溢废水污染农田土壤中V、Cr、Mn、Co、Ni、Cu、Zn、Rb、Sr、Mo、Cd、Sn、Sb、Pb、U及As的含量分析,研究揭示了金属冶炼废水外溢这一突发性污染事件对农田土壤的污染状况及其污染特征.结果表明,污染土壤中Zn、Mn、As、Pb、Cd、Sb等金属浓度分别为113.28～212.22、251.67～2 429.29、34.44～130.28、50.63～544.74、63.44～317.33、39.41～551.17 mg/kg,远高于背景值,土壤不仅受到As污染,还有Zn、Mn、Pb、Cd、Sb等重金属的严重污染;相关性分析表明,污染程度与当地有色金属矿产开发冶炼活动密切相关,且污染物有相似的来源或相近的释放规律;剖面分析表明,表层土壤的pH值较低,土壤酸化明显,部分金属如Zn、Cr、Cd等表现出先升高后降低变化趋势.本研究揭示了冶炼废水外溢造成的突发性环境污染事故引起的土壤重金属污染特征,并为开展污染治理提供了理论依据.

Pollution characteristics of heavy metals in the farmland soil nearby a metal smelter were studied.Soil samples were collected and the contents of elements V,Cr,Mn,Co,Ni,Cu,Zn,Rb,Sr,Mo,Cd,Sn,Sb,Pb,U and As in the bulk samples of soil profiles were measured,with the objectives to identify the pollution status and pollution characteristics of the farmland soil that were suffered from smelter effluents flooding,an acute pollution accident.The results indicate that the concentrations of heavy metals Zn,Mn,As,Pb,Cd,Sb in the soil were 113.28-212.22,251.67-2 429.29,34.44-130.28,50.63-544.74,63.44-317.33,39.41-551.17 mg/kg,respectively,higher than the background level.These polluted soils not only have high concentrations of As,but also of the Zn,Mn,Pb,Cd and Sb.According to correlation analysis,pollution level is closely with local nonferrous metal exploitation,and principal pollutants have the same source.Some trace metals,such as Zn,Cr,Cd,show increasing concentration first and then decreasing trend in the soil profile.Soil acidification appears in the topsoil.This study has characterized the metal pollution in soils flooded by sudden smelting effluents spilling,and provided a theory base for pollution treatment.