College of Environmental Science, Sichuan Agricultural University, Wenjiang 611130, China; Institute of Environmental Sciences (CML), Leiden University, P. O. Box 9518, 2300 RA Leiden, The Netherlands.
College of Environmental Science, Sichuan Agricultural University, Wenjiang 611130, China.
Sci Total Environ. 2018 Jun 1;625:1021-1029. doi: 10.1016/j.scitotenv.2018.01.019. Epub 2018 Jan 5.
Soil washing with chelators is a promising and efficient method of remediating metals-contaminated soils. However, the toxicity of residual metals and the effects on soil microbial properties have remained largely unknown after washing. In this study, we employed four biodegradable chelators for removal of metals from contaminated soils: iminodisuccinic acid (ISA), glutamate-N,N-diacetic acid (GLDA), glucomonocarbonic acid (GCA), and polyaspartic acid (PASP). The maximum removal efficiencies for Cd, Pb, and Zn of 85, 55, and 64% and 45, 53, and 32% were achieved from farmland soil and mine soil using biodegradable chelators, respectively. It was found that the capacity of ISA and GLDA to reduce the labile fraction of Cd, Pb, and Zn was similar to that of the conventional non-biodegradable chelator ethylenediaminetetraacetic acid (EDTA). The leachability, mobility, and bioaccessibility of residual metals after washing decreased notably in comparison to the original soils, thus mitigating the estimated environmental and human health risks. Soil β-glucosidase activity, urease activity, acid phosphatase activity, microbial biomass nitrogen, and microbial biomass phosphorus decreased in the treated soils. However, compared with EDTA treatment, soil enzyme activities distinctly increased by 5-94% and overall microbial biomass slightly improved in the remediated soils, which would facilitate reuse of the washed soils. Based on soil toxicity tests that employed wheat seed germination as the endpoint of assessment, the washed soils exhibited only slight effects especially after ISA and GLDA treatments, following high-efficiency metal removal. Hence, ISA and GLDA appear to possess the greatest potential to rehabilitate polluted soils with limited toxicity remaining.
螯合剂土壤淋洗是一种很有前景且高效的修复重金属污染土壤的方法。然而，在淋洗之后，残留金属的毒性及其对土壤微生物特性的影响在很大程度上仍然未知。在这项研究中，我们使用四种可生物降解的螯合剂来去除污染土壤中的金属：亚氨基二琥珀酸（ISA）、谷氨酸-N,N-二乙酸（GLDA）、葡萄糖单羧酸（GCA）和聚天冬氨酸（PASP）。对于农田土壤和矿山土壤，分别使用可生物降解的螯合剂实现了 Cd、Pb 和 Zn 的最大去除效率 85%、55%和 64%和 45%、53%和 32%。研究发现，ISA 和 GLDA 降低 Cd、Pb 和 Zn 可利用态分数的能力与传统的不可生物降解螯合剂乙二胺四乙酸（EDTA）相似。与原始土壤相比，淋洗后残留金属的浸出性、迁移性和生物可利用性显著降低，从而减轻了估计的环境和人类健康风险。处理后的土壤中β-葡萄糖苷酶活性、脲酶活性、酸性磷酸酶活性、微生物生物量氮和微生物生物量磷均降低。然而，与 EDTA 处理相比，经修复的土壤中土壤酶活性分别增加了 5-94%，整体微生物生物量略有提高，这将有利于淋洗土壤的再利用。基于采用小麦种子发芽作为评估终点的土壤毒性测试，在高效去除金属后，淋洗土壤仅表现出轻微的影响，尤其是在使用 ISA 和 GLDA 处理之后。因此，ISA 和 GLDA 似乎具有最大的潜力，在毒性有限的情况下修复污染土壤。
