A new method of evaluation of element pollutant mobility in sediments

The application of a strong chelating agent for the screening test of element mobility in sedimentary systems was investigated. Single-step and sequential extraction procedures were applied to four sediment samples collected from an industrially polluted region of Eastern Slovakia. A sequential extraction procedure (SEP), recommended by the Institute for Reference Materials and Measurements (IRMM), was applied and used as a reference extraction method. A single-step extraction with 0.05 mol dm−3 ethylenediaminetetraacetic acid (EDTA) was adapted for sediments when extraction conditions were optimised. The extraction efficiency of the single-step procedure was compared with that of SEP. The contents of elements extracted by Na2EDTA were in good agreement with the sum of the first three steps of the SEP for Fe, Mn, and Co. Na2EDTA can therefore be considered capable to extract the majority of elements associated with the reducible sedimentary phase — bound to Fe and Mn oxides in the regional geological conditions of the monitored region. Thus, Na2EDTA extraction of Fe and Mn can serve as an economical, time-saving supplementary test for the IRMM procedure.