增施CO2对C3和C4植物根际氯氰菊酯残留浓度的影响

CO2减排和土壤污染修复是我国实现经济和环境可持续发展必须解决的两大难题.基于生物固碳对根际微环境的影响,本研究提出通过增施CO2强化土壤有机污染的植物修复过程,为同时解决CO2减排和土壤污染植物修复面临的困境提供新思路.在模拟的CO2增施环境中,以C3植物菜豆和C4植物玉米为供试植物,以氯氰菊酯为目标污染物,研究增施CO2对C3和C4植物根际氯氰菊酯残留浓度的影响.结果表明,增施CO2可显著增加C3植物菜豆的地上和地下干重,在氯氰菊酯添加浓度为0、20、40 mg.kg-1时地下干重分别比自然CO2水平时增加了54.3%、31.9%和30.0%.增施CO2提高了未添加氯氰菊酯土壤的菜豆根际微生物数量,但降低了添加氯氰菊酯土壤的菜豆根际微生物数量.增施CO2对未添加氯氰菊酯土壤的菜豆根际氯氰菊酯残留浓度没有显著影响,但降低了菜豆根际氯氰菊酯的残留浓度,分别比自然CO2水平时下降24.0%（20mg.kg-1）和16.9%（40 mg.kg-1）.然而,对C4植物玉米而言,增施CO2对植物生物量、根际微生物、根际氯氰菊酯残留浓度下降没有明显促进作用,甚至有抑制作用.本实验表明,增施CO2降低了C3植物根际氯氰菊酯残留浓度,可以考虑将增施CO2作为C3植物修复土壤污染的强化措施,但对C4植物的影响还有待进一步研究.

Effect of CO2 Fertilization on Residual Concentration of Cypermethrin in Rhizosphere of C3 and C4 Plant

In order to achieve sustainable economic and environmental development in China, CO₂-emission reduction and phytoremediation of polluted soil must be resolved. According to the effect of biological carbon sequestration on rhizosphere micro-environment, we propose that phytoremediation of polluted soil can be enhanced by CO₂ fertilization, and hope to provide information for resolving dilemma of CO₂-emission reduction and phytoremediation technology. In this study, effects of CO₂ fertilization on cypermethrin reduction in rhizosphere of C3-plant (bush bean) and C4-plant (maize) were investigated. Results showed that dry weight of shoot and root of bush bean (C3 plant) was increased by CO₂ fertilization. Relative to ambient CO₂, dry weight of root was increased by 54.3%, 31.9% and 30.0% in soil added with 0, 20 and 40 mg·kg^-1 cypermethrin respectively. Microbial biomass was increased by CO₂ fertilization in rhizosphere soil added with 0 mg·kg^-1 cypermethrin, but negative effect was found in rhizosphere soil added with 20 and 40 mg·kg^-1 cypermethrin. CO₂ fertilization slightly affected residual concentration of cypermethrin in rhizosphere soil added with 0 mg·kg^-1 cypermethrin, but significantly decreased residual concentration of cypermethrin as 24.0% and 16.9% in soil added with 20 and 40 mg·kg^-1 relative to ambient CO₂.In maize plant, however, plant growth, microbial biomass and residual cypermethrin concentration in rhizosphere was slightly affected by CO₂ fertilization, and even negative effect was observed. This study indicated that CO₂ fertilization decreases the residual concentration of cypermethrin in rhizosphere of C3-plant, and it is possible to enhance phytoremediation of organic-polluted soil by C3-plant through CO₂ fertilization. However, further study is needed for C4-plant.