中文摘要：

以小麦和玉米2种陆生植物为金属吸收材料,利用盆栽试验比较研究了新型DGT（diffusive gradients in thin films,薄膜扩散梯度技术）法与5种传统化学法评价土壤中Zn复合存在下Cd的生物有效性.结果显示：1土壤中w（Cd）为4 mgkg时明显抑制了2种植物的生长,与对照组相比,小麦的地上部和根系生物量分别降低了26.2%和23.4%,玉米的分别降低了23.5%和30.9%.2Zn的添加能够减轻Cd对植物的毒害,并促进植物生长;Cd污染土壤中Zn的复合存在会抑制2种植物对Cd的吸收,并随w（Zn）的增加其抑制作用更加明显;DGT法、土壤溶液法测定的土壤溶液中ρ（Cd）和4种化学提取法（HAc、EDTA、CaCl2和NaAc）测定的土壤中w（有效态Cd）均随w（Zn）的增加而明显降低.3Pearson相关分析显示,2种植物体内w（Cd）与6种方法表征的土壤中w（有效态Cd）均呈显著正相关（R〉0.900,P〈0.01）,但植物体内w（Cd）与DGT和土壤溶液法测定的土壤溶液中ρ（Cd）的R（〉0.940）大于其他4种化学提取法.可见,对于评价Cd-Zn复合污染土壤中Cd的生物有效性而言,DGT与土壤溶液法均优于传统的化学提取法.

英文摘要：

A newly developed technique of DGT（ diffusive gradients in thin films） has been proposed as a promising tool for predicting cadmium（ Cd） bioavailability in soils. However,there are considerable debates on its suitability. In the present study,Cd bioavailability under combined pollution of Cd and zinc（ Zn） in soils was evaluated by comparing the DGT technique with five traditional chemical methods,including soil solution concentration and four extractants（ HAc,EDTA,NaAc and CaCl2）. The results showed that： 1） Zn addition in single Cd-polluted soils alleviated Cd toxicity to wheat and maize,and was accompanied by a decrease of Cd uptake in two plant tissues. Compared with the control group,the biomasses of shoot and root clearly decreased by 26. 2% and 23. 4% for wheat,and by 23. 5% and 30. 9% for maize. 2） The bioavailable concentrations of Cd measured by six methods clearly decreased with increasing addition of Zn in single Cd-polluted soils. 3） Pearson correlation analysis showed that there existed significant and positive correlations（ P〈0.01,R 〉0.900） between Cd concentrations in two plant tissues and each bioavailable indicator of Cd in soils. However,DGT determination and soil solution concentration significantly correlated（ R 〉0. 940） with plant Cd concentrations compared with four chemical extraction methods. The present study verified that DGT technique and soil solution concentration should be superior to traditional extraction methods for evaluating Cd bioavailability in combined pollution of Cd and Zn in soils.