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-1 and 0.01 mg·L-1 respectively.The sum of lead found in 8 species of 4 samples were 147.9 mg·kg-1 the deviation of which were less than 10% of the value of total lead (159.9 mg·kg-1) found directly in the sample.