Fractionation Analysis of Sediments – Limitations in the Extractant Selectivity

Abstract

Sequential extraction procedures (SEPs) are commonly used for fractionation of solid element forms in sediments and soils. Many SEPs have been developed and, despite numerous criticisms, they remain very useful. This paper reviews extractants used in various schemes, with their advantages and disadvantages, and compares the use of SEPs with the single-step extraction with a strong complexing agent. The single-step leaching with a strong complexing agent (after optimisation of extraction conditions in accordance with local specificities) is able to release mobile and potentially mobile metal forms associated with specific sediment phases. With respect to the published experiments, it can be stated that the extraction with a strong complexing agent could well be used for the screening of sediment pollution. This is an economical and time-saving test supplementary to the recommended and attested IRMM (Institute for Reference Materials and Measurements) extraction protocol and can also be used as a rapid alarming indicator of element mobility changes in sedimentary systems. Usually, such information on stream sediment pollution is sufficient for decision making in environmental protection.