Sukreeyapongse Orathai, Holm Peter E, Strobel Bjarne W, Panichsakpatana Supamard, Magid Jakob, Hansen Hans Christian Bruun
Dep. of Soil Science, Kasetsart University, Phaholyathin, Chatujak, Bangkok, 10900, Thailand.
J Environ Qual. 2002 Nov-Dec;31(6):1901-9. doi: 10.2134/jeq2002.1901.
The pH-dependent release of cadmium, copper, and lead from soil materials was studied by use of a stirred flow cell to quantify their release and release rates, and to evaluate the method as a test for the bonding strength and potential mobility of heavy metals in soils. Soil materials from sludge-amended and nonamended A horizons from a Thai coarse-textured Kandiustult and a Danish loamy Hapludalf were characterized and tested. For each soil sample, release experiments with steady state pH values in the range 2.9 to 7.1 and duration of 7 d were performed. The effluent was continuously collected and analyzed. Release rates and total releases were higher for the Hapludalf than the Kandiustult and higher for the sludge-amended soils than the nonamended soils. With two exceptions the relative release rates (release rate/total content of metal in soil) plotted vs. steady state pH followed the same curves for each metal, indicating similar bonding strengths. These curves could be described by a rate expression of the form: relative release rate = k[H+]a, with specific a (empirical constant) and k (rate constant) parameters for each metal demonstrating that metal release in these systems can be explained by proton-induced desorption and dissolution reactions. With decreasing pH, pronounced increases in release rates were observed in the sequence cadmium > lead > copper, which express the order of metal lability in the soils. The flow cell system is useful for comparison of metal releases as a function of soil properties, and can be used as a test to rank soils with respect to heavy metal leaching.
通过使用搅拌流动池研究了土壤材料中镉、铜和铅的pH依赖性释放，以量化它们的释放量和释放速率，并评估该方法作为土壤中重金属结合强度和潜在迁移性测试的可行性。对来自泰国质地粗糙的老成土的污泥改良和未改良A层以及丹麦壤质的简育湿润老成土的土壤材料进行了表征和测试。对于每个土壤样品，进行了稳态pH值范围为2.9至7.1且持续时间为7天的释放实验。连续收集并分析流出物。简育湿润老成土的释放速率和总释放量高于老成土，污泥改良土壤的释放速率和总释放量高于未改良土壤。除两个例外情况外，每种金属的相对释放速率（释放速率/土壤中金属的总含量）与稳态pH的关系曲线相同，表明结合强度相似。这些曲线可以用以下形式的速率表达式描述：相对释放速率 = k[H⁺]ᵃ，每种金属具有特定的a（经验常数）和k（速率常数）参数，这表明这些系统中的金属释放可以用质子诱导的解吸和溶解反应来解释。随着pH的降低，观察到释放速率按镉>铅>铜的顺序显著增加，这表明了土壤中金属活性的顺序。流动池系统可用于比较不同土壤性质下的金属释放情况，并可作为对土壤重金属淋溶进行排序的测试方法。
