生物螯合剂EDDS与非生物螯合剂EDTA联合施用下植物提取土壤重金属及潜在环境风险

Extraction of Heavy Metals in Soils by Plants in the Case of Joint Application of Biotic Chelating Agent EDDS and Non-biotic Chelating Agent EDTA and Potential Environmental Ricks

本文通过盆栽试验研究单一螯合剂EDTA、EDDS以及复合螯合剂的不同EDTA/EDDS配比对玉米和油菜作物重金属Pb、Cu、Cd的富集程度,并且通过淋滤实验分析各种螯合剂处理的土壤淋滤液重金属含量和土壤营养元素流失情况。结果表明:螯合剂的存在明显增加了植物重金属Pb、Cu、Cd的富集系数。植物重金属Pb富集系数在添加复合螯合剂配比3(EDTA/EDDS=1∶2)时,达到最高;重金属Cu富集系数在添加复合螯合剂配比2(EDTA/EDDS=2∶1)时,达到最高7.3;重金属Cd富集系数在添加单一螯合剂EDTA时达最高。土壤重金属淋滤液浓度在添加复合螯合剂不同EDTA/EDDS配比时比单一施用螯合剂要低。玉米组淋滤液中TN平均浓度高低依次为EDTA>EDDS>配比3>配比1>配比2。油菜组淋滤液中TN平均浓度高低依次为EDTA>EDDS>配比1>配比2>配比3。玉米组TP平均流失浓度高于空白对照组TP平均流失浓度72%,油菜组TP平均流失浓度高于空白对照组TP平均流失浓度54%。

In order to find out the effect of single chelating agents EDTA and EDDS and composite chelating agent EDTA/EDDS on the enrichment ratios of heavy metals such as Pb, Cu, and Cd in corn and canola crops, and through experimental analysis of various chelating agents we revealed the contents of heavy metals leached by soil and the wastage of soil nutrient elements. The results showed that the presence of chelating agents significantly increased the heavy metal （Pb, Cu, Cd） enrichment factors of plants. The highest heavy metal （Pb） enrichment factor of plants appeared when the composite ratio of chelating agents reached 3（EDTA/EDDS= 1 ： 2） ; the highest heavy metal （Cu） enrichment factor of plants （7.3） appeared when the composite ratio of chelating agents reached 2（EDTA/EDDS--2 ： 1）; the highest heavy metal （Cd） enrichment factor of plants appeared when a single chelating agent EDTA was applied. The leachate concentrations of heavy metals in soil were lower in the case of adding composite chelating agents at different EDTA/EDDS ratios than those in the case of adding a single chelating agent. In corn group leachate the TN average concentrations follow the order of EDTA〉 EDDS：〉 ratio 1 〉 ratio 2 〉 ratio 3. In rape group leachate the TN average concentrations follow the order of EDTA：〉 EDDS） ratio 1） ratio 2〉 ratio 3. The TP average loss concentrations of corn group TP are higher than the average concentrations of control group （72%）. The TP average loss concentrations of rapes are higher than the average concentrations of control group （54%）.