有机化合物和硝酸溶液对复合污染土壤中Cu、Zn、Pb释放的影响

研究了等浓度的不同有机酸、有机盐、人工螯合剂和不同浓度HNO3 溶液对复合污染土壤中Cu、Zn、Pb的浸提性及其潜在释放性。结果表明 :四种有机酸对铜的释放顺序为 :柠檬酸 >草酸 >酒石酸 >苹果酸 ,对锌的释放顺序为 :柠檬酸 >苹果酸 >草酸 >酒石酸 ,对铅的释放顺序为 :柠檬酸 >酒石酸 >苹果酸 >草酸 ;有机盐对这些金属的释放顺序较为一致 :EDTA >柠檬酸钠 >草酸钠 >酒石酸钾钠 (铅为酒石酸钾钠 >草酸钠 )。对这三种金属来说 ,铜是最易释放的元素 ,锌次之 ,铅最差。从释放特征来看 ,各种有机化合物对不同的金属表现不尽相同 ,人工螯合剂EDTA、柠檬酸钠、有机酸对铜 ,EDTA、酒石酸钾钠对铅 ,1molL-1HNO3 和0 .1molL-1HNO3 对铜、锌、铅等的释放速率较快 ;草酸钠对铜、锌 ,草酸对铅 ,0 .0 1molL-1HNO3 对铜、锌、铅等的释放速率较慢 ,其它释放剂的释放速率介于两者之间

INFLUENCES OF ORGANIC COMPOUNDS AND NITRIC ACID SOLUTIONS ON RELEASE OF COPPER, ZINC AND LEAD FROM A MIXED METAL-POLLUTED AGRICULTURAL SOIL

A promising method for removing heavy metals from contaminated soil is phytoremediation. Heavy metal cations are strongly adsorbed onto the negatively charged soil particles, which limits the development of phytoremediation. To enhance metal solubility and bioavailability, some natural or synthetic chelators (e.g. organic acids and EDTA) and inorganic acids have been used. In this study organic chelators such as Citric acid, Oxalic acid, Tartaric acid, Malic acid and their salts, EDTA and Nitric acid solutions for soil metal activation were used.The results showed that the trends of Cu, Zn and Pb released by the organic acids were: Citric acid>Oxalic acid>Tartaric acid>Malic acid for Cu, Citric acid>Malic acid>Oxalic acid>Tartaric acid for Zn and Citric acid>Tartaric acid>Malic acid>Oxalic acid for Pb. The organic sodium salts including Citrate, Tartarate and Oxalate had lower release capacity, but synthetic chelator EDTA had higher release capacity, and the releasing trends of Cu and Zn by the organic salts were EDTA>Citrate>Oxalate>Tartarate, but for Pb, the order was EDTA>Citrate>Tartarate>Oxalate. 1.0 mol L -1 and 0.1 mol L -1 HNO 3 had the highest release capacity, which had significant difference from that of 0.01 mol L -1 HNO 3. Considering their application to enhancement phytoremediation, EDTA and Citric acid with higher release capacity would have more promising potential in term of protection of soil quality.