The importance of organic matter distribution and extract soil:solution ratio on the desorption of heavy metals from soils.
The importance of organic matter distribution and extract soil:solution ratio on the desorption of heavy metals from soils.
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DOI：
10.1016/s0048-9697(01)01000-2
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发表时间：
2002-03
期刊：
影响因子：
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通讯作者：
Yujun Yin;C. Impellitteri;S. You;H. Allen
中科院分区：
文献类型：
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作者：
Yujun Yin;C. Impellitteri;S. You;H. Allen
对于相似的土壤总金属浓度，金属的可移动性(移动性和生物有效性)因土壤性质的不同而显著不同。我们研究了从15种不同的、未经改良的土壤中解吸铜、镍和锌。这些研究包括评估土壤：溶液萃取率和土壤性质对金属解吸的影响。通过计算每种金属在每种土壤中的分配系数(Kd)来检查每种金属的解吸情况，其中Kd=[M]土壤/[M]溶液。土壤：溶液比的研究结果表明，金属的Kd值随土壤：溶液比的增加而增加。这一结果也适用于土壤有机质(SOM)的分布。由于土壤：溶液比对测量的金属分布有显著影响，我们选择较高的土壤：溶液比，以便更接近自然土壤条件。铜对可操作定义的溶解有机物(DOM)表现出很强的亲和力。在本研究中，根据萃取物的0.45-μm或0.22-μm滤液中的总有机碳(TOC)含量来确定DOM。Kdof铜与Kdof有机质(Kd-om)呈线性相关(R2=0.91)，其中Kd-om等于Walkley-Black湿法测得的SOM，转换为总碳(TC)的系数为0.59。通过总有机碳分析(DOM)，将代表固相总胆固醇的这些值除以可溶有机碳。以固相碳和溶液碳为基础，采用0.59的换算系数来构建Kd-om值。土壤有机质对铜在土壤系统中的去向起着重要作用。土壤溶液中镍、锌的分布和游离Cu2+的活性与土壤有机质密切相关，而与DOM关系不大。特定土壤中镍、锌和游离Cu2+的Kd值除以同一土壤中的土壤有机质含量。将镍、锌和游离Cu2+的Kd值归一化为土壤有机质含量，显著改善了非归一化Kd值与土壤pH之间的线性关系。半经验归一化回归方程可以用来预测镍、锌的溶解度和游离Cu2+的活度随pH的变化。
The lability (mobility and bioavailability) of metals varies significantly with soil properties for similar total soil metal concentrations. We studied desorption of Cu, Ni and Zn, from 15 diverse, unamended soils. These studies included evaluation of the effects of soil:solution extraction ratio and the roles of soil properties on metal desorption. Desorption was examined for each metal by computing distribution coefficients (Kd) for each metal in each soil where Kd=[M]soil/[M]solution. Results from soil:solution ratio studies demonstrated that Kdvalues for the metals tended to increase with increasing soil:solution ratio. This result also held true for distribution of soil organic matter (SOM). Because the soil:solution ratio has a significant effect on measured metal distributions, we selected a high soil:solution ratio to more closely approach natural soil conditions. Copper showed strong affinity to operationally defined dissolved organic matter (DOM). In this study, DOM was operationally defined based on the total organic carbon (TOC) content in 0.45-μm or 0.22-μm filtrates of the extracts. The Kdof Cu correlated linearly (r2=0.91) with the Kdof organic matter (Kd-om) where the Kd-omis equal to SOM as measured by Walkley–Black wet combustion and converted to total carbon (TC) by a factor of 0.59. These values representing solid phase TC were then divided by soluble organic carbon as measured by TOC analysis (DOM). The conversion factor of 0.59 was employed in order to construct Kd-omvalues based on solid phase carbon and solution phase carbon. SOM plays a significant role in the fate of Cu in soil systems. Soil–solution distribution of Ni and Zn, as well as the activity of free Cu2+, were closely related to SOM, but not to DOM. Kdvalues for Ni, Zn and free Cu2+in a particular soil were divided by the SOM content in the same soil. This normalization of the Kdvalues for Ni, Zn, and free Cu2+to the SOM content resulted in significant improvements in the linear relationships between non-normalized Kdvalues and soil pH. The semi-empirical normalized regression equations can be used to predict the solubility of Ni and Zn and the activity of free Cu2+as a function of pH.