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作 者 ：武慧斌,于志红,周莉,唐世荣,宋正国

期 刊 ：植物营养与肥料学报 2014年 20卷 6期 页码：1525-1533

关键词：土壤；二氧化碳；螯合剂；铜蓄积量；向日葵；

Keywords:soil, CO2, chelating agent, Cu accumulation, sunflower,

摘 要 ：【目的】以向日葵为研究材料,探讨其在CO₂浓度升高条件下修复铜(Cu)污染土壤的效率以及对比CO₂与螯合剂联合诱导下向日葵对铜污染土壤修复效率的差异,并筛选出对CO₂浓度升高响应显著的品种,以期为利用植物修复铜污染土壤提供数据支撑。【方法】 在设置两个CO₂浓度的人工气候室内(正常浓度370 μmol/mol和升高浓度800 μmol/mol),采用完全随机设计的盆栽土培试验,通过5个不同品种的向日葵,向铜污染水平为100mg/kg的土壤上施加不同浓度EDTA和DTPA,研究CO₂浓度与螯合剂联合施用对向日葵修复铜污染土壤效率的影响。【结果】 1)不同螯合剂用量对铜污染土壤的浸提效果显著不同,根据螯合剂浸提土壤铜的高含量低毒性效应,选取EDTA 3 mmol/kg土和DTPA 5 mmol/kg土作为螯合剂的施加剂量。2)施入螯合剂后,CO₂浓度升高一定程度上缓解了向日葵的失绿、 失水,增加了食葵3号和阿尔泰2号的总生物量,但降低了食葵4号和阿尔泰1号的总生物量。3)在相同CO₂浓度下,加入螯合剂后明显提高土壤pH值,且DTPA处理的增幅明显高于EDTA处理。CO₂浓度升高处理虽对土壤pH值有影响,但CO₂施肥与不施肥处理间五个品种的土壤pH值无显著差异。4)试验选用的5个品种中,食葵4号、 阿尔泰1号在CO₂浓度升高后,向日葵地上部蓄铜量明显降低;食葵3号、 油生引2号在CO₂浓度升高后,向日葵地上部蓄铜量略有升高;阿尔泰2号在二氧化碳浓度升高后,向日葵地上部蓄铜量明显升高。CO₂与DTPA 5 mmol/kg土联合施用, 5个品种向日葵茎叶内铜含量较对照增加239％～646％;铜蓄积量较对照增加230％～362％。二氧化碳与EDTA 3 mmol/kg 联合施用时,EDTA的活化作用未达到最佳效果,对5个品种向日葵茎、 叶内铜含量的影响不一致。【结论】CO₂浓度升高一定程度上可以增强向日葵的抗性。在100 mg/kg铜污染土壤上,阿尔泰2号对二氧化碳浓度升高的反应最敏感,同时二氧化碳与螯合剂联合施用时,螯合剂可能是影响土壤pH值变化的主要因子。在铜污染水平为100 mg/kg的土壤上,与EDTA施用量为3 mmol/kg土相比,5 mmol/kg土的DTPA与CO₂联合施用的修复效果更好。

Abstract:【Objectives】The aim of this study was to investigate efficiency of sunflower’s phytoremediation in copper-contaminated soil under different CO₂ concentration levels and various chelating agents. Furthermore, this study aimed to screen CO₂-sensitive cultivars of sunflowers, therefore, providing data tosupport the need for phytoremediation of copper-contaminated soil.【Methods】A pot experiment was conducted in artificial climate chambers under two CO₂ concentration levels, normal (370 μmol/mol) and elevated (800 μmol/mol). Using a completely randomized design, five different cultivars of sunflowers in soil contaminated with 100 mg/kg Cu were treated with different concentrations of EDTA and DTPA to determine the effects of a chelating agent in combination with various levels of CO₂ concentration on repair efficiency of sunflowers in Cu-contaminated soil.【Results】1) The extraction of Cu from the contaminated soil using different chelating agents is significantly different. Based on the low toxicity followed by high concentration of chelate when extracting Cu from contaminated soil, EDTA 3 mmol/kg soil and DTPA 5 mmol/kg soil are selected. 2) The loss of green in leaves and dehydration of sunflowers are relieved to some extent under the elevated CO₂ concentration following the application of chelating agents. Furthermore, the total biomass amounts of Shikui-3 and Altai-2 are increased, while those of Shikui-4 and Altai-1 are decreased. 3) Soil pH values are increased in the treatments with chelating agents at both CO₂ concentrations, and the extent of the increase in the DTPA treatments is significantly higher than that in the EDTA treatments. Although the elevated CO₂ concentration has an impact on soil pH, there was no significant difference in soil pH between the two CO₂ levels for the five sunflower cultivars. 4) The above-ground Cu accumulation in Shikui-4 and Altai-1 significantly decreased under conditions of elevated CO₂.The Cu accumulation amounts in shoots of Shikui-3 and Youshengyin-2 are slightly increased under conditions of elevated CO₂, while the amount in shoots of Altai-2 is significantly increased. The Cu concentrations of sunflower leaves and stems in the treatments with 5 mmol/kg soil DTPA under elevated CO₂ conditions are increased by 239%-646% compared with the controls, and the Cu accumulation amounts of the plants are increased by 230%-362%. The results also show that the effect of Cu concentrations in stems and leaves of sunflowers are consistent. The mobilization of Cu in soils is more active in the DTPA treatments compared with the EDTA treatments.【Conclusions】Sunflower resistance to Cu can be enhanced to some extent under conditions of elevated CO₂. Altai-2 is the most sensitive to elevated CO₂ in 100 mg/kg Cu-contaminated soil. It is possible that the application of chelating agents is a main factor of affecting the soil pH change under conditions of elevated CO₂. TheDTPA 5 mmol/kg treatment is more effective in the remediation of Cu-contaminated soil (100 mg/kg) under the elevated CO₂ condition compared with EDTA 3 mmol/kg.

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