3种提取剂对不同类型土壤重金属的提取效果

为了研究不同提取剂对不同类型土壤重金属的提取效果，选用3种提取剂(DTPA、HCl、EDTA)提取2种母质（红壤、紫色土）发育的稻田土壤（黄泥田、紫泥田）重金属Zn、Pb、Cd和Cu的含量，比较它们的提取效果。结果表明，提取剂的提取量和提取率大小有明显差异。DTPA提取Zn、Pb、Cd、Cu的含量均值分别为135.88、167.20、5.09、17.63 mg/kg；HCl提取Zn、Pb、Cd、Cu的含量均值分别为244.79、299.97、7.74、28.75 mg/kg；EDTA提取Zn、Pb、Cd、Cu的含量均值分别为220.31、490.33、7.22、35.46 mg/kg。3种提取剂对重金属Zn、Cd提取量大小为HCl>EDTA>DTPA，对Pb、Cu提取量大小为EDTA>HCl>DTPA。从元素的提取率看，除黄泥田DTPA提取为Cd>Cu>Pb>Zn外，一般均为Cd>Pb> Cu>Zn。就不同土壤类型而言，黄泥田重金属提取率大小均为EDTA>HCl>DTPA；紫泥田Zn、Cd提取率大小为HCl>EDTA>DTPA，而Pb、Cu为EDTA>HCl>DTPA。黄泥田、紫泥田提取Pb、Cu的提取率均为EDTA>HCl>DTPA。因此不同类型土壤应该使用不同的提取剂，暗示适当提取剂的提取量可以预测糙米中重金属的累积量。

The Extraction Efficiency of Three Extracting Agents for Heavy Metals in Different Types of Soil

The aim of this paper was to study the extraction efficiency of different extracting agents for heavy metals in different types of soil. Three extracting agents (DTPA, HCl, EDTA) were used to extract heavy metals (Zn, Pb, Cd, Cu) in yellow paddy soil and purple paddy soil, and the extraction efficiency of them were compared. The results showed that, it had significantly difference in extraction amount and extraction rate of different extracting agents to the different types of soil. The average content of Zn, Pb, Cd, Cu which were extracted by DTPA were 135.88 mg/kg, 167.20 mg/kg, 5.09 mg/kg, 17.63 mg/kg in paddy soil, respectively. The average content of Zn, Pb, Cd, Cu which were extracted by HCl were respectively 244.79 mg/kg, 299.97 mg/kg, 7.74 mg/kg, 28.75 mg/kg in paddy soil. EDTA extracted Zn, Pb, Cd, Cu from paddy soil, the average content of them were 220.31 mg/kg, 490.33 mg/kg, 7.22 mg/kg, 35.46 mg/kg, respectively. The extraction amount of Zn, Cd of three extracting agents were found to be of the order HCl > EDTA > DTPA, while that of Pb and Cu were EDTA > HCl > DTPA. From the extraction rate of elements perspective, besides the sequence of extraction rate of elements was Cd >Cu >Pb >Zn, which were extracted by DTPA in yellow paddy soil, others followed the sequence Cd >Pb >Cu >Zn. From the view of different types of soil, the extraction rate of heavy metals in yellow paddy soil followed the order EDTA > HCl > DTPA, while that of Zn, Pb, Cd and Cu were HCl > EDTA > DTPA, EDTA > HCl > DTPA, HCl > EDTA > DTPA, EDTA > HCl > DTPA in purple paddy soil, respectively. In short, the extraction rate of Pb and Cu in two type paddy soils were found to be of the sequence EDTA > HCl > DTPA. In summary, when the availability of heavy metals of soil was studied, different types of soil should use different extracting agents. Meanwhile, the results suggested that, the accumulation of heavy metals of brown rice might be predicted by extraction amount of suitable extracting agent.