电解锰废渣重金属对周边农田土壤的污染及模拟酸雨作用下的溶出特性

为综合评估电解锰废渣堆场在酸雨作用下溶出的重金属对周边农田造成的环境污染程度,采用定点取样和实验室分析相结合的方法对废渣堆场周边不同范围土壤进行了现场污染调查和采样分析,用不同pH溶液模拟酸雨对电解锰废渣进行浸出和淋溶试验。结果表明:渣场周边5m处土壤中Se、Cr、Zn、Ni、Pb含量均高于电解锰废渣与底泥;在渣场50m处农田土壤中Mn含量为287mg/kg,超过《土壤环境质量标准》中规定阈值250mg/kg;Cr浓度为233.7mg/kg,已接近标准规定的阈值250mg/kg。Mn、Se、Zn、Cr、Ni、Pb等重金属的浸出浓度随pH的升高而降低,pH为4.5时,浸出液中Mn、Se浓度达到729mg/kg和14.05mg/kg,分别超过《污水综合排放标准》中规定的阈值552倍和10.13倍;在酸雨淋溶前期约100min内,电解锰废渣中重金属随淋溶液溶出明显,酸雨pH值的降低会加剧电解锰废渣对周边环境的影响。

Pollution of Heavy Metals in the Soils Around Electrolytic Manganese Residue and Dissolving-out Characteristics of Heavy Metals in Waste Residues in Simulated Acid Rain

To comprehensively assess the heavy metal pollution on the farmland around Electrolytic Manganese Residue(EMR)in the role of acid rain,the hazards of these heavy metals on the environment were investigated,the effects of simulation acid rain on the heavy metal leaching and eluviations were also analyzed.The results showed that the concentrations of heavy metals around EMR(less than 5 meters)were higher than manganese waste and sediment.Compared with the Soil Environmental Quality Standards,the concentrations of Mn and Cr was highly up to 287 mg/kg and 233.7 mg/kg on the farmland 50 m away from EMR,the former exceeded its threshold and the latter close to the threshold too.The results showed that the released concentration of the heavy metals(Mn、Se、Zn、Cr、Ni、Pb) in EMR increased with the decrease of rainfall pH.The concentrations of Mn and Se both exceeded their thresholds in the Integrated Wastewater Discharge Standard when pH was 4.5,the concentrations of Mn and Se exceeded 552(729 mg/kg) and 10.13(14.05 mg/kg) times of their standard.About 100 min in the early leaching of acid rain,the leaching of the heavy metals in EMR were obvious.Contamination of the heavy metal around EMR increased along with pH reduction.