Multistage sequential extraction with different sequences was applied to extracting natural surface coa tings(NSCs), and the results were compared with those by single stage extraction technique. The optimal sequential extraction scheme with the best performance was selected and incorporated into the method of selective extraction followed by adsorption and statistic analyses to study the adsorption parameters of Fe oxides, Mn oxides and organic matters in NSCs for Pb and Cd, to validate the applicability of the sequential extraction scheme. The Langmuir ad sorption parameters of each component of surface coating estimated according to the adsorption data of single stage extraction of NSCs were all similar to those of sequential extraction of NSCs, and the maximum difference between the metal adsorption abilities of the components estimated via the two extraction techniques was only about 20%, in dicating that either extraction techniques could be used. The optimal sequential extraction scheme obtained was first extracted with NH2OH·HCl, then with Na2S2O4, and finally with oxalic acid.
HUA Xiu-yi, LIU Xiao-xue, DONG De-ming, LI Ming and LI Yao-rui Key Laboratory of Groundwater Resources and Environment, Ministry of Education, Key Lab of Water Resources and Aquatic Environment of Jilin Province, College of Environment and Resources, Jilin University, Changchun 130012, P. R. China
