EDTA和有机酸对毛竹修复重金属污染土壤的强化作用

摘要

以毛竹Phyllostachys edulis幼苗和重金属污染土壤为研究对象,通过土柱淋洗试验,施加乙二胺四乙酸(EDTA,1.5和3.0 mmol·kg-1)和有机酸(15.0和30.0 mmol·kg-1),研究了毛竹叶片叶绿素荧光特性、 毛竹各部位重金属质量分数、 土壤液中重金属质量分数和EDTA质量浓度的变化.结果表明:施加EDTA和有机酸都抑制毛竹叶绿素荧光特性,且在30.0 mmol·kg-1的有机酸处理下,毛竹叶片叶绿素荧光特性受到的抑制效果最为显著.EDTA施加能够促进毛竹对锌、 铜和镉的吸收,而有机酸处理对毛竹吸收重金属无促进作用,施加3.0 mmol·kg-1EDTA对表层土壤中铜、 锌和镉的活化作用最强.20和40 cm土层土壤溶液中重金属质量分数随时间慢慢积累,分别在第4次收集后达到稳定和在最后一次收集液中达到最大;而添加有机酸后土壤溶液中重金属质量分数则在第2次土壤收集液中达到最大,随后逐渐降低.土壤溶液中EDTA主要集中在5 cm土层,且随时间增加显著降低,在5～9 d内EDTA质量浓度相对稳定,分别为110.9～122.9和257.8～263.3 mg·L-1.综上,EDTA可以有效地提高重金属生物有效性,强化植物修复重金属污染土壤,但使用时应综合考虑其环境风险.%Taking moso bamboo (Phyllostachys edulis) seedlings and heavy metal contaminated soil for re-search object, the changes of chlorophy fluorescence parameter, concentration of heavy metals in plant and concentration of heavy metal and EDTA in soil solution were studied through soil column leaching test, which was expected to provide scientific basis for the strength of chelate-induced phytoremediation of contaminated soils. The results revealed that chlorophy fluorescence parameter was inhibited while treated with EDTA and organic acids, and the inhibitory effects reached peak at the treatment of 30.0 mmol·kg-1 organic acids. The addition of EDTA promoted the uptake of Zn, Cu and Cd by moso bamboo, while it was useless for organic acids. The activation effect reached peak under the treatment of 3.0 mmol·kg-1 EDTA. The concentration of heavy metal in the soil layer of 20 and 40 cm increased along with time, and achieved stability after 4 times collection, and reached peak at the last collection. For the soils treated with organic acids, they reached peak at the second collection, and then decreased gradually. The content of EDTA in soil solution was mainly con-centrated in the 5 cm soil layer, and decreased along with time, and then kept stability at the fifth and ninth day, which was at the range of 110.9-122.9 mg·L-1 and 257.8-263.3 mg·L-1 respectively. It could be conclud-ed that potential phytoremediation capability of moso bamboo in heavy metals contaminated soils would be en-hanced effectively with application of EDTA, however, the environmental risks should be considered syntheti-cally when using.