化学淋洗对土壤团聚体稳定性及其重金属赋存形态的影响
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1.重庆大学环境与生态学院;2.教育部深空探测联合研究中心;3.重庆大学环境与生态学院,教育部深空探测联合研究中心;4.中国电建集团成都勘测设计研究院有限公司

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Effects of chemical washing on the stability of soil aggregates and the form of heavy metals
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1.College of Environment and Ecology,Chongqing University;2.China;3.Center of Space Exploration,Ministry of Education,Chongqing University;4.College of Environment and Ecology, ChongQing University;5.Powerchina Chengdu Engineering Corporation Limited

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    摘要:

    为探究重金属在土壤非均质体系中的淋洗特性,分别考察了3种化学淋洗剂乙二胺四乙酸(EDTA)、柠檬酸和三氯化铁(FeCl3)等对粒径为0.25-2 mm、0.05-0.25 mm和<0.05 mm的土壤团聚体淋洗过程中团聚体结构、重金属Pb和Cd浓度及其赋存形态影响。结果表明,不同粒径团聚体中重金属的淋洗效率存在显著差异(P<0.05),小粒径(<0.05 mm)的团聚体上Pb和Cd具有更高的淋洗效率。淋洗后较小粒径团聚体上残渣态Cd所占比例升高,但有效态的Pb所占比例增加。淋洗后团聚体的平均直径(WMWD)分别减小了77.25%、80.98%和49.15%,团聚体解体可能增加土壤对Pb和Cd的专性吸附能力。淋洗剂FeCl3相较于EDTA和柠檬酸,对水稳性团聚体具有较低的结构破坏作用,同时具有较好的重金属淋洗效果,有利于土壤后续的安全再利用。

    Abstract:

    In order to investigate characteristics of heavy metals removal with chemical washing from soil which was considered as a heterogeneous system, the soil aggregate were screened and graded on particle sizes of 0.25-2 mm, 0.05-0.25 mm and <0.05 mm. Then the effects of EDTA, citric acid and ferric chloride (FeCl3) on aggregate structure, lead (Pb) and cadmium (Cd) concentrations and their speciation during washing were investigated. The results show that the removal rates of heavy metals in aggregates with different particle sizes were significantly different (P<0.05). Pb and Cd in small aggregates (particle sizes <0.05 mm) had higher removal rates than that in big ones. After washing, the proportion of residual state Cd on small aggregates increased, while the proportion of effective state Pb increased. After washing, the average diameter (WMWD) of the aggregates decreased by 77.25%, 80.98% and 49.15%, respectively, and the disintegration of water-stable aggregates may increase the specific adsorption capacity of soil to Pb and Cd. Compared with EDTA and citric acid, FeCl3 has lower structural damage to water-stable aggregates and better heavy metal leaching effect, which is beneficial to the subsequent safe reuse of soil.

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  • 收稿日期:2019-12-13
  • 最后修改日期:2020-03-20
  • 录用日期:2020-03-22
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