Mao L C, Young S D, Tye A M, Bailey E H
Division of Agricultural and Environmental Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire LE12 5RD, United Kingdom; School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai, 200093, China.
Division of Agricultural and Environmental Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire LE12 5RD, United Kingdom.
Environ Pollut. 2017 Dec;231(Pt 2):1529-1542. doi: 10.1016/j.envpol.2017.09.013. Epub 2017 Sep 22.
Metal-salt amended soils (MA, n = 23), and historically-contaminated urban soils from two English cities (Urban, n = 50), were investigated to assess the effects of soil properties and contaminant source on metal lability and solubility. A stable isotope dilution method, with and without a resin purification step, was used to measure the lability of Cd, Cu, Ni, Pb and Zn. For all five metals in MA soils, lability (%E-values) could be reasonably well predicted from soil pH value with a simple logistic equation. However, there was evidence of continuing time-dependent fixation of Cd and Zn in the MA soils, following more than a decade of storage under air-dried conditions, mainly in high pH soils. All five metals in MA soils remained much more labile than in Urban soils, strongly indicating an effect of contaminant source on metal lability in the latter. Metal solubility was predicted for both sets of soil by the geochemical speciation model WHAM-VII, using E-value as an input variable. For soils with low metal solution concentrations, over-estimation of Cd, Ni and Zn solubility was associated with binding to the Fe oxide fraction while accurate prediction of Cu solubility was dependent on humic acid content. Lead solubility was most poorly described, especially in the Urban soils. Generally, slightly poorer estimation of metal solubility was observed in Urban soils, possibly due to a greater incidence of high pH values. The use of isotopically exchangeable metal to predict solubility is appropriate both for historically contaminated soils and where amendment with soluble forms of metal is used, as in toxicological trials. However, the major limitation to predicting solubility may lie with the accuracy of model input variables such as humic acid and Fe oxide contents where there is often a reliance on relatively crude analytical estimations of these variables. Trace metal reactivity in urban soils depends on both soil properties and the original source material; the WHAM geochemical model predicts solubility using isotopically exchangeable metal as an input.
研究了金属盐改良土壤（MA，n = 23）以及来自英国两个城市的历史污染城市土壤（Urban，n = 50），以评估土壤性质和污染物来源对金属活性和溶解度的影响。采用一种稳定同位素稀释法，有或没有树脂纯化步骤，来测量镉、铜、镍、铅和锌的活性。对于MA土壤中的所有五种金属，其活性（%E值）可以用一个简单的逻辑方程从土壤pH值进行合理预测。然而，有证据表明，在空气干燥条件下储存十多年后，MA土壤中的镉和锌仍存在随时间持续的固定现象，主要发生在高pH值土壤中。MA土壤中的所有五种金属的活性仍比城市土壤中的高得多，这有力地表明污染物来源对后者金属活性有影响。利用地球化学形态模型WHAM-VII，将E值作为输入变量，对两组土壤的金属溶解度进行了预测。对于金属溶液浓度低的土壤，镉、镍和锌溶解度的高估与它们与铁氧化物部分的结合有关联，而铜溶解度的准确预测则取决于腐殖酸含量。铅的溶解度最难描述，尤其是在城市土壤中。一般来说，在城市土壤中观察到对金属溶解度的估计略差，这可能是由于高pH值的发生率更高。在历史污染土壤以及在毒理学试验中使用可溶性金属进行改良的情况下，使用同位素可交换金属来预测溶解度都是合适的。然而，预测溶解度的主要限制可能在于模型输入变量（如腐殖酸和铁氧化物含量）的准确性，因为这些变量往往依赖于相对粗略的分析估计。城市土壤中痕量金属的反应性取决于土壤性质和原始源材料；WHAM地球化学模型利用同位素可交换金属作为输入来预测溶解度。
