pH/离子强度变化时Cu/Cd复合污染土壤解吸和迁移特征
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青岛大学

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国家自然科学基金项目(面上项目,重点项目,重大项目)


Desorption and Migration Characteristics of Cu/Cd Composite Contaminated Soil under pH/ Ionic Strength Change
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Qingdao University

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the National Natural Science Foundation of China

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    摘要:

    重金属污染土壤在用固化/稳定化技术修复后,若外部环境发生变化,失去活性的重金属会否再次释放出来并在土壤中迁移,造成污染风险,是一个值得探讨的重要科学问题。为揭示不同化学因素对污染土壤中重金属活化及迁移过程的影响,通过室内土柱实验,研究了不同离子强度、pH及阳离子类型(Ca2+、Na+)下Cu2+、Cd2+在土壤中的解吸及迁移行为。结果表明:总的来说,离子强度增大,Cu2+、Cd2+淋出浓度峰值也随之增大;另外,在CaCl2淋溶阶段,0.005、0.01、0.05、0.1 mol·L-1 CaCl2时,Cu2+、Cd2+解吸量依次增加且Cd2+的解吸量高于Cu2+,而0.5 mol·L-1 CaCl2时抑制了Cd2+的解吸且Cu2+的解吸量高于Cd2+。pH减小时,Cu2+、Cd2+解吸量增大,即偏酸性的环境有利于Cu2+、Cd2+的解吸;但从Cu2+、Cd2+浓度峰值来看,pH为3时的Cu2+、Cd2+浓度峰值反而小于pH为4、5时。Ca2+比Na+更有利于Cu2+、Cd2+的解吸,但在0.005 mol·L-1时,NaCl溶液更有利于Cu2+的解吸,并且去离子水淋溶阶段Cu2+浓度要高于CaCl2淋溶阶段;此外,离子强度为0.005、0.05和0.5 mol·L-1 NaCl的三种情况下均出现了土壤颗粒的出流,且0.05和0.5 mol·L-1 NaCl时,存在流速下降的现象。

    Abstract:

    【Objective】Some changes in the external environment are often observed after the remediation of heavy metal polluted soils with solidification stabilization technology. Thus, an important scientific question worth discussing is whether the inactivated heavy metals will be released again and migrate in the soil, causing pollution risk, and under what conditions.【Method】In order to reveal the effects of different chemical factors on the activation and migration of heavy metals in contaminated soil, the desorption and migration behavior of Cu2+ and Cd2+ in soil under different ionic strength, pH and cation types (Ca2+, Na+) were studied by laboratory soil column experiments.【Result】In general, the peak leaching concentration of Cu2+ and Cd2+ increased with the increase in ionic strength. Using CaCl2 as a leaching agent, the desorption capacity of Cu2+ and Cd2+ increased at 0.005, 0.01, 0.05 and 0.1 mol·L-1 CaCl2, and the desorption capacity of Cd2+ was higher than that of Cu2+. However, 0.5 mol·L-1 CaCl2 inhibited the desorption of Cd2+ and the desorption of Cu2+ was higher than that of Cd2+. When pH decreased, the desorption of Cu2+ and Cd2+ increased, that is, the acidic environment was conducive for the desorption of Cu2+ and Cd2+. However, the concentration peak of Cu2+ and Cd2+ at pH 3 was smaller than that at pH 4 and 5. Ca2+ was more favorable for the desorption of Cu2+ and Cd2+ than Na+, but NaCl solution was more favorable for the desorption of Cu2+ at 0.005 mol·L-1. Also, the concentration of Cu2+ in the leaching stage with deionized water was higher than that in the leaching stage with CaCl2. In addition, soil particles exhaled at 0.005, 0.05 and 0.5 mol·L-1 NaCl, and the flow rate decreased at 0.05 and 0.5 mol·L-1 NaCl.【Conclusion】The increase in ionic strength, decrease in pH and presence of divalent cations were beneficial to the desorption and migration of heavy metals in soil. This study provides a theoretical basis for soil remediation and heavy metal release after soil remediation.

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引用本文

李静,徐绍辉. pH/离子强度变化时Cu/Cd复合污染土壤解吸和迁移特征[J].土壤学报,,[待发表]
lijing, xushaohui. Desorption and Migration Characteristics of Cu/Cd Composite Contaminated Soil under pH/ Ionic Strength Change[J]. Acta Pedologica Sinica,,[In Press]

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