Applicable Scope of Techniques in Speciation Analysis for Heavy Metals in Sediments

A summary and approach was made to the applicable scope of various techniques in chemical speciation of heavy metals in sediments. Among various extractants used in single extraction process, deionized water and neutral salt solutions are suitable for evaluation of biotoxicity, dilute acid solution scan be used in analysis of geochemical activity of heavy metals, and chelating reagents are preferred in determination of bio-availability. The single extraction process is not suitable for use in treatment of alkaline sediments with low contents of heavy metals. More information on species of the elements can be obtained by the successive extraction process, however, due to the low selectivity of extractants used in the process, "comparative study" by selecting the BCR method or the Tessier method which are high in referential ability, should be made. In the separation of heavy metal particles adhered on fine particles or colloids of sediments by the Field Flow Fractionation or by the Size Exclusion chromatography, choice of eluants (acting as the mobile phase) is ultra-important. Before the process of extraction, main physical and chemical properties of the sample should be well-known by pre-testings, so as to reduce the probablity and magnitude of change of chemical species of the heavy metals as far as possible (91 ref. cited).