螯合剂对土壤中镉赋存形态及其生物有效性的影响

EFFECTS OF CHELATORS ON SPECIES AND BIOAVAILABILITY OF CADMIUM IN SOIL

以胡萝卜作为试验植物,研究了EDTA,EGTA,DTPA和柠檬酸四种螯合剂对土壤中Cd的赋存形态及生物有效性的影响.结果表明,在碱性土壤中,加入螯合剂EDTA,EGTA和DTPA都能显著改变土壤中Cd的赋存形态,增加有效态Cd的百分比含量,改善Cd的生物有效性;但施加柠檬酸对Cd的赋存形态没有产生明显影响,各形态组成与对照组基本一致.同时,试验结果还显示,胡萝卜中Cd含量随着添加螯合剂浓度的增加先增大而后有所降低,但除柠檬酸处理组外,均明显高于对照组,表明四种螯合剂均能增强胡萝卜对Cd的吸收,且以EGTA效果最佳,EDTA和DTPA次之,柠檬酸最差.

By the pot incubation test, using carrot （Daucus carota var. sativa） as the test plant, the effects of four chelators, e.g. EDTA, EGTA, DTPA and citric acid, on the species and bioavailability of cadium in the soils were studied in the present research. It was indicated that EDTA, EGTA and DTPA could greatly change the species of Cd in the tested alkali soils with increased percentage concentration of available Cd and improved bioavailability; however citric acid was of insignificance to this change as the species of Cd in the test soils were similar to those in the control soils. Furthermore, the test results showed that the concentrations of Cd in the carrot increased firstly and then decreased slightly with the increased chelators＇ concentrations, and they were all much higher than those in the control groups except for the test group treated with citric acid, which indicated that all the four chelators could enhance the uptake of Cd by the carrot, with EGTA standing first, EDTA and DTPA taking second place and citric acid closing up the rear.