3种螯合剂对向日葵修复镉污染土壤的影响

Effects of Three Cheating Agents on Rehabilitation of Cd-contaminated Soil with Sunflower

研究螯合剂对向日葵在镉污染土壤下的吸收、转运、富集特性具有重要意义。在每千克土中施用镉的浓度为15 mg/kg,同时分别投加2.5、5.0和7.5 mmol/kg的乙二胺二琥珀酸(EDDS)、草酸(OA)和柠檬酸(CA),研究了其对向日葵生长、吸收土壤中镉,以及对土壤中镉的活化性能的影响。结果表明:2.5 mmol/kg OA、CA处理下,向日葵生物量略增,其他处理均使向日葵生物量有不同程度的降低。在高浓度螯合剂处理时,降幅最大;在5.0 mmol/kg EDDS处理下,向日葵根部、地上部及单株镉含量最大,分别为92.73、89.15和92.58 mg/kg,是CK的5.51倍、2.34倍及4.45倍;在7.5 mmol/kg EDDS处理下,向日葵的转运系数最高时为1.075,是对照组的1.99倍;土壤镉的活化性最大时为10.96 mg/kg,是对照组的1.42倍。EDDS的添加比OA和CA更显著地增加了土壤镉的活化性,同时显著提高了向日葵的富集系数和转运能力。综合看来,螯合剂的投加能有效活化土壤中的镉,促进植物转运、吸收。

This paper focuses on the effects of chelating agents on absorption, accumulation and transport characteristics of sunflower growing in Cd contaminated soil. To study the effects, a pot experiment was conducted which involved to the soil the addition of 15 mg/kg of Cd, at the same time, 2.5 mmol/kg of EDDS, 5.0 mmol/kg of OA and 7.5 mmol/kg of CA; then the effects on sunflower growth, the Cd absorption and the activation property of Cd in the soil were investigated. The study found that application of 2.5 mmol/kg of OA and 2.5 mmol/kg of CA to the Cd contaminated soils slightly promoted an increase of biomass of sunflowers; while other chelating agents resulted in decreases in certain degrees. Besides, it was found that application of 5 mmol/kg EDDS resulted in the maximum values of Cd in roots, shoots and single plant, the transfer coefficient could be expected to reach 1.075, 1.99 times of the control group; the greatest activated Cd in the soil could be of10.96 mg/kg, which was 1.42 times of that of the control group. Therefore, properly addition of the chelating agent was effectively conducive to Cd mobilization in soil, and promoted the uptake of Cd by sunflowers and transfer of Cd from the roots to shoots.