两种外源有机酸对土壤Cd形态及秋华柳Cd积累的影响

秋华柳(Salix variegate Franch.)因具有良好的重金属耐受和积累能力，常被作为重金属污染土壤修复工程物种.通过盆栽模拟试验，分析了不同浓度外源草酸和酒石酸处理下土壤Cd形态的变化和秋华柳Cd含量的积累特征，以探究外源有机酸在Cd污染土壤植物修复中的应用潜力.结果表明:添加外源酒石酸可显著降低土壤非有效性Cd含量，增加土壤中以可交换态Cd为主的有效性Cd含量，促进了秋华柳对Cd的积累，同时也显著提升了植株的富集系数，其中添加5 mmol/kg酒石酸的处理效果最佳.与CK相比，添加5 mmol/kg外源酒石酸可显著增加秋华柳根、茎和叶中的Cd积累量，地上、地下部分和全株的Cd积累量分别提升了62.2%、75.9%和78.4%，地上和地下部分富集系数分别提升了173.0%和178.8%.添加外源草酸对土壤有效性Cd含量没有显著影响，秋华柳根、茎和叶的Cd含量和积累量无明显提升.研究显示，添加较低浓度的酒石酸更有利于增加土壤中可交换态Cd含量和有效性Cd含量，促进秋华柳对土壤中Cd的吸收和积累，增强秋华柳对Cd污染土壤的修复能力，可应用于Cd污染土壤的植物修复. 

Effects of Exogenous Organic Acids on Cd Forms in Soil and Cd Accumulation in Salix variegate Franch

With the rapid development of industry and agriculture, heavy metal pollution in soil has become more serious. Phytoremediation technology is widely used in cleaning up contaminated soil due to its low cost and no secondary pollution. However, the low bioavailability of heavy metals in soil and the low biomass of many hyper accumulators affect the phytoremediation of heavy metal contaminated soils. Low molecular weight organic acids (LMWOAs) are considered to apply in the remediation of contaminated soil because they can improve the mobility of heavy metals in soil and promote the release of heavy metals bound soil, therefore enhancing the activity of heavy metals in soil. Salix variegate Franch. is often used as engineering species for phytoremediation due to its good performance in terms of tolerance and accumulation of heavy metals. In order to reveal the application potential of exogenous organic acids in enhancing phytoremediation of Cd contaminated soil, pot experiments were conducted. The changes of soil Cd forms and the Cd accumulation characteristics of S. variegata were studied under different concentrations of exogenous oxalic acid and tartaric acid treatments. The results showed that exogenous tartaric acid treatments significantly reduced the content of non-available Cd in soil, increased the content of exchangeable Cd, promoted the Cd accumulation of S. variegata, and significantly increased the bioaccumulation coefficient of plants. Compared with the control treatments, 5 mmol/kg tartaric acid treatment significantly increased the Cd accumulation in aboveground, underground parts and whole plant under by 62.2%, 75.9% and 78.4%, respectively, and enhanced the bioaccumulation coefficient of aboveground and underground parts by 173.0% and 178.8%, respectively. However, the addition of oxalic acid had no significant effect on the content of available Cd in soil, and the content and accumulation of Cd in all organs of S. variegata. Therefore, the addition of 5 mmol/kg tartaric acid enhanced the ability of S. variegata to remediate Cd in soil, because it increased the exchangeable and available Cd content in soil. This method is suitable for phytoremediation of Cd contaminated soil.