微波萃取土壤中重金属形态的分析研究

Microwave Extraction of Heavy Metals from Soil for Speciation Analysis

利用微波的能量研究了经改进的Tessier系列萃取法,并用此法萃取分析了土壤中重金属的形态。结果表明,用微波萃取重金属的前3步形态所需时间为10.5 min,仅是常规振荡萃取的1/69,Cu、Fe、Pb和Zn的第1形态(可交换态)、第2形态(碳酸盐结合态)和第3形态(铁-锰氧化物结合态)部分的微波萃取效率是常规振荡萃取的101%～772%,但Mn和Ni在第2形态的结果稍微偏低,Ni在第1形态的结果也偏低。两种萃取方法所得的结果基本吻合,样品1中可萃取的Cu、Fe、Mn、Ni、Pb和Zn主要以第3形态存在。样品2中可萃取的Cu、Fe、Mn、Ni和Pb也主要与第3形态部分相关;而可萃取的Zn则主要以第4形态(有机质结合态)存在。

Microwave energy was utilized to study the modified Tessier sequential extraction procedure which isused to extract and analyze the speciation of heavy metals in soils. Compared with the conventional extraction （CE） using vibration, the time for microwave extraction（ME） of first three speciation fractions for heavy metals was 10.5 minutes, only 1/69 of CE; and the extraction efficiency of Cu, Fe and Pb was 101%-772%, higher than the CE, but Mn and Ni were slightly lower in the second speciation fraction（carbonate）, Ni was lower in the first speciation fraction（exchangeable）. The results for both of the extraction methods were almost similar. The extractable Cu, Fe, Mn, Ni, Pb and Zn in the sample No.1 mainly existed in the third speciation fraction （Fe-Mn oxide）, and the extractable Cu, Fe, Mn, Ni and Pb in the third speciation fraction in the sample No.2 were also related with the third soeciation fraction （Fe-Mn oxide）; the extractable Zn existed in the organic matter.