人工合成铁、铝矿物和镁铝双金属氧化物对土壤砷的钝化效应

应用室内模拟培养的方法,研究了人工合成铁、铝矿物和镁铝双金属氧化物对砷超标土壤中砷的钝化效果.每种钝化剂均设置0.1％、0.5％、1.0％、2.5％和5.0％五个添加量处理.结果表明,添加水铝矿明显降低了土壤pH值,其中,添加5％水铝矿的处理降幅最大,达到1.20；而添加镁铝双金属氧化物则显著提高了土壤pH值,5％镁铝双金属氧化物的处理土壤pH值由5.04最高可提高至8.09.添加铁铝矿物均降低了土壤有效砷的含量,下降幅度为1.89％～64.15％；而添加镁铝双金属氧化物则使土壤有效砷含量增加；添加水铁矿和针铁矿处理对提高土壤中残留态砷含量的作用较为明显.总体看来,两种人工合成铁矿较镁铝双金属氧化物和水铝矿对土壤中砷有更好的钝化效果,可以作为钝化剂应用于土壤中砷的钝化.

Immobilization effects of synthetic Fe/Al minerals and Mg/Al layered double oxides (Mg/Al-LDO) additions on arsenic (As) in soils

Laboratory incubation experiments were conducted to investigate the immobilization effects of synthetic Fe/Al minerals and Mg/Al layered double oxides (Mg/Al-LDO) additions on arsenic (As) in As-contaminated soils. Five different addition rates (0.1%, 0.5%, 1.0%, 2.5% and 5.0%) in soils were set in each amendment. The results showed that the soil pH obviously decreased and had the maximum decrease value of 1.20 units by adding 5% of gibbsite. In contrast, the soil pH significantly increased from 5.04 to 8.09 by adding 5% of Mg/Al layered double oxides. The contents of available As in soils decreased by 1.89%~64.15% by adding goethite, ferrihydrite and gibbsite, while increased by adding Mg/Al layered double oxides. The contents of residual As in soils obviously increased by adding goethite and ferrihydrite. Overall, goethite and ferrihydrite showed a better immobilization effect of arsenic (As) than Mg/Al-LDO and gibbsite, and could be applied as amendments to immobilize As in soils.