柠檬酸对褐土中DTPA提取态铜、镉含量及对紫花苜蓿吸收铜、镉的影响

为了阐述有机酸对土壤中重金属生物有效性的影响,通过盆栽实验,研究了Cu、Cd复合污染下柠檬酸对褐土中二乙基三胺五乙酸(DTPA)提取态铜和镉含量的影响,并探讨了柠檬酸对植物吸收铜、镉的影响。结果表明,土壤中DT-PA-Cu含量随柠檬酸添加量的增加而减小,添加高浓度铜(Cu 1 000)处理中,DTPA-Cu含量减小更明显。在添加低铜浓度(Cu600)处理下,柠檬酸添加量为2和12 mmol/kg时,土壤DTPA-Cu含量随土壤镉含量的增加而增加,而柠檬酸含量为5mmol/kg时,DTPA-Cu含量在低镉处理(Cd 1)时含量最低。紫花苜蓿中铜含量随柠檬酸添加量的增加明显降低。土壤中DTPA-Cd含量随柠檬酸添加量的增加而减小,且随铜添加量的增加而降低。紫花苜蓿中的镉含量随柠檬酸添加量的增加先增加后减小;在相同柠檬酸添加量处理时,紫花苜蓿中镉的含量随镉含量的增加而增加;在低镉处理下,铜的加入对较低柠檬酸浓度时紫花苜蓿镉含量影响不明显,但柠檬酸浓度为12 mmol/kg时,紫花苜蓿中镉含量随铜添加量的增加而明显增加。

Effect of citric acid(CA) on DTPA extractable Cu & Cd content in cinnamon soil and Cu & Cd uptake by alfalfa

A pot experiment was conducted to investigate the effects of citric acid (CA) on DTPA extractable Cu (DTPA-Cu) and Cd (DTPA-Cd) content in Cu-Cd compound contaminated cinnamon soil, and also the effects of CA on the uptake of Cu and Cd by alfalfa were discussed. The results indicated that soil DTPA-Cu concentration decreased with the addition of CA increased, and DTPA-Cu concentration reduced significantly in the higher Cu addition (Cu 1 000) treatment. When the CA added amount was 2 and 12 mmol/kg, soil DTPA-Cu concentration increased with the soil Cd added amount increased in the lower Cu addition (Cu 600) treatment. However, when added CA amount was 5 mmol/kg, the lowest soil DTPA-Cu concentration occurred in the treatment of Cd added content was 1 mg/kg (Cd 1). The Cu concentration in alfalfa decreased significantly with added CA amount increased. The soil DTPA-Cd concentration decreased with added CA and Cu amount increased. The Cd concentration in alfalfa increased first and then decreased as the added CA amount increasing. And in the treatments of the same CA added amount, the Cd concentration in alfalfa raised with the increased of Cd addition. And in the treatment of lower Cd addition, there was no significant effect of Cu addition on Cd concentration in alfalfa when CA added amount was very lower, but when the CA added amount was 12 mmol/kg, Cd concentration in alfalfa increased significantly with the addition of Cu increased.