Leaching of heavy metals from contaminated soils: An experimental and modeling study
Leaching of heavy metals from contaminated soils: An experimental and modeling study
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DOI：
10.1021/es049885v
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发表时间：
2004-08-15
影响因子：
11.4
通讯作者：
Comans, RNJ
中科院分区：
文献类型：
--
作者：
Dijkstra, JJ;Meeussen, JCL;Comans, RNJ
在本文中，我们的特点浸出的重金属（镍，铜，锌，镉，铅）从8个污染土壤在很宽的pH值范围内（pH值0.4-12），使用一个原始的方法的基础上，结合选择性的化学提取和地球化学建模批pH值静态浸出实验。重金属的浸出浓度通常远低于总浓度，并表现出强烈的pH依赖性，导致“V形”浸出曲线与溶液浓度的数量级变化。所用的“多表面”模型结合了对溶解和固体有机物（NICA-Donnan）、铁/铝（氢）氧化物（广义两层模型）和粘土（Donnan模型）的吸附。应用这些模型而不进行修改，并且仅使用结合常数和参数的标准组（即，不带任何装饰）。重金属浸出的模型预测一般是足够的，有时是优秀的。从形态计算的结果是一致的公认的重要性，有机物作为土壤中的主要活性固相。所观察到的土壤之间的差异，相对于元素形态在固相中对应于土壤中存在的反应表面的相对量。在溶液相中，与溶解的有机物（DOM）的复合物在大多数pH范围内占主导地位。游离金属离子（Me 2+）通常是低于pH 4的主要物质。在这项研究中使用的实验和建模方法的组合被证明是有前途的，因为它导致了一个更基本的了解土壤中的pH值依赖的淋溶过程。研究表明，采用选定的吸附模型的“多表面”建模方法能够充分预测在各种条件下受污染土壤中重金属的浸出，而无需任何参数拟合。
In this paper, we characterize the leaching of heavy metals (Ni, Cu, Zn, Cd, and Pb) from eight contaminated soils over a wide range of pH (pH 0.4-12) using an original approach based on batch pH-static leaching experiments in combination with selective chemical extractions and geochemical modeling. The leached concentrations of the heavy metals are generally much lower than the total concentrations and show a strong pH dependency, resulting in "V-shaped" leaching curves with orders of magnitude changes in solution concentrations. The "multisurface" model used incorporates adsorption to dissolved and solid organic matter (NICA-Donnan), iron/aluminum (hydr)oxide (generalized two-layer model) and clay (Donnan model). These models were applied without modifications, and only the standard set of binding constants and parameters was used (i.e., without any fitting). The model predictions of heavy metal leaching are generally adequate and sometimes excellent. Results from speciation calculations are consistent with the well-recognized importance of organic matter as the dominant reactive solid phase in soils. The observed differences between soils with respect to element speciation in the solid phase correspond to the relative amounts of the reactive surfaces present in the soils. In the solution phase, complexes with dissolved organic matter (DOM) are predominant over most of the pH range. Free metal ions (Me2+) are generally the dominant species below pH 4. The combination of the experimental and modeling approach as used in this study is shown to be promising because it leads to a more fundamental understanding of the pH-dependent leaching processes in soils. The "multisurface" modeling approach, with the selected sorption models, is shown to be able to adequately predict the leaching of heavy metals from contaminated soils over a wide range of conditions, without any fitting of parameters.