利用原位技术对比传统方法研究土壤镉的生物有效性

Comparative Study on Cadmium Bioavailability in Polluted Soils between In Situ Technique and Traditional Methods

薄膜扩散梯度技术(DGT)是一种评价土壤重金属生物有效性的新型方法,但该技术与传统评价方法的优劣存在争论。以2种常见陆生植物小麦和玉米为供试材料,通过DGT和传统方法对比研究土壤中镉(Cd)的生物有效性。结果显示室内模拟添加的土壤中低浓度的Cd对供试植物的生长影响不大;2种植物的地上部与根系部吸收富集Cd的浓度随土壤添加Cd浓度增加而显著增加;DGT、土壤溶液及6种常用化学提取法所表征的有效态Cd的浓度皆随添加Cd浓度的增加而呈现增加的趋势,Pearson相关性分析下8种评价方法得到的Cd浓度皆与植物体内富集Cd含量具有一定的相关性,表明室内模拟实验下DGT和传统化学提取法均可预测土壤Cd污染的生物有效性;而在野外污染土壤实验中DGT表现出对Cd生物有效性评价的优势性,且较其他方法能够模拟植物动态富集Cd,认为DGT是评价土壤Cd污染生物有效性的优选方法。

Diffusive gradients in thin film technique （DGT） has been regarded as a promising tool in soil for the evaluation of cadmium （Cd） availability. In this study, wheat and maize species were chosen for Cd uptake. Cd bioavailability was systemically investigated by comparing this technique with seven traditional methods. The results showed that low added amounts of Cd takes few effect on the biomass of wheat. Cadmium concentrations in shoots and roots of two plants increased with the increased level of Cd in soils. Furthermore, the bioavailable concentration of Cd measured by all methods increased near linearly with the increasing addition of Cd in soil. Positive correlations were observed between various bioavailable indicators of Cd in soils and Cd concentrations in two plant, while the field tests come to an opposite conclusion. The results implied that DGT measurement can predict the bioavailable levels of Cd in soil solutions effectively and it is a superior tool for the prediction of Cd bioavailability in soil.