低分子量有机酸强化烟草修复镉污染土壤的适用性研究

采用盆栽试验,以0.125mmol/kg EDTA为对照,研究3种低分子量有机酸(酒石酸、柠檬酸和草酸)在强化烟草修复镉污染土壤中应用的可行性。3种低分子量有机酸(LMWOA)均可显著降低土壤pH,提高镉的有效含量,酒石酸和草酸对镉在烟草中转运有抑制作用,柠檬酸在酸性土壤中促进镉在烟草中转运,在中性土壤中则起抑制作用。31.25mmol/kg LMWOA对烟草地上部的生长有一定的促进作用,该浓度的柠檬酸和草酸使酸性土壤中烟草地上部镉累积量分别提高42.95%和28.67%,柠檬酸还使中性土壤中烟草地上部镉的累积量提高40.91%,所有酒石酸处理镉在烟草地上部的累积量均降低,EDTA使酸性土壤中烟草地上部镉的累积量提高24.56%,对中性土壤中烟草地上部镉累积量的影响不显著。表明柠檬酸和草酸具有强化烟草地上部对镉的吸收、提高烟草提取土壤镉效率的作用,但要获得与EDTA相当的效果,需大大提高其用量,这必然导致修复成本大大提高,故不宜用于强化烟草修复镉污染土壤。

Feasibility of Low Molecular Weight Organic Acids in Enhancing Phytoextraction of Cadmium from Soils with Tobacco(Nicotiana tabacum L.)

A pot experiment was conducted to investigate the feasibility of three low molecular weight acids(LMWOA) including tartaric acid,citric acid and oxalic acid in enhancing phytoextraction of cadmium from soils with tobacco(Nicotiana tabacum L.).Three kinds of LMWOA could decrease soil pH,consequently increased the availability of cadmium in soils.The translocation of cadmium in tobacco was inhibited by tartaric acid-and oxalic acid-treatments,and citric acid treatment in neutral soil,but was promoted by citric acid treatment in acid soil.LMWOA at the rate of 31.25 mmol/kg increased the shoot weight of tobacco.At this rate,cadmium accumulation in the shoot of tobacco increased by 42.95% and 28.67%,respectively,on citric acid-and oxalic acid-treated acid soil,while increased by 40.91% on citric acid-treated neutral soil.All tartaric acid treatment decreased cadmium accumulation in tobacco shoot.These results illustrated that citric acid and oxalic acid at the rate of 31.25 mmol/kg could enhance cadmium extraction from soils with tobacco.However,to obtain equal extraction efficiency as that of EDTA,the amounts of the two kinds of LMWOA have to be increased.It was suggested that LMWOA be unsuitable to enhance extraction of cadmium from soil with tobacco.