土壤中铅的含量及其化学形态分析

对广州市黄埔港区所取土壤中铅的化学形态分析进行了研究。采用含不同组分提取剂的连续提取程序对1 g土壤进行提取,使之分成8种形态的铅,并用火焰原子吸收光谱法(FAAS)对每种提取所得的形态中的铅进行了测定。另在一份试样中直接测定其总铅量,对提取剂的组成及其溶液的浓度及提取操作条件进行了研究和优化,对FAAS测定方法的仪器工作条件作了说明。试验结果表明,所取试样中大部分铅以稳定的结合形态存在,以可交换态和碳酸盐结合态存在的铅仅达6%,总铅量随土壤深度的增加而减少。FAAS测定方法的灵敏度和检出限依次为0.007 mg.L-1及0.01 mg.L-1,分析和测定了4个试样中8种形态的铅量,其加和量为147.9 mg.kg-1,与直接测得的总铅量(159.9 mg.kg-1)之间的偏差小于10%。

STUDY ON THE CONTENT OF LEAD IN SOIL AND ITS CHEMICAL SPECIATION

A study on the chemical speciation of lead in soil taken from Huangpu port district in Guangzhou was performed and reported in this paper.A successive extraction program using different extractants was applied to 1 gram of soil sample to separate the lead into 8 different species and lead content in each of the extracted species was determined by FAAS.The composition and concentration of the extractants,and the working conditions of the extraction procedure were studied and optimized.The optimum instrumental parameters used in the FAAS determination were described.As shown by experimental results,most of lead in soil sample taken were present in the form of stable species.Lead present as the exchangeable species and as the carbonate combined species amounted only around 6%,the amounts of total lead decreased with the increase of depth of soil.The sensitivity and detection limit of the FAAS method were found to be 0.007 mg.L-1and 0.01 mg.L-1respectively.The sum of lead found in 8 species of 4 samples were 147.9 mg.kg-1the deviation of which were less than 10% of the value of total lead(159.9 mg.kg-1) found directly in the sample.