Fractionation of mercury in sediments from coastal zone inundated by tsunami and in freshwater sediments from the rivers.

The study was undertaken to compare the mobility and bioavailability of mercury in tsunami sediments from the coastal zone of Thailand left after the 26 December 2004 tsunami event and freshwater sediments from the Vistula and the Warta rivers in Poland. The mobility and bioavailability of mercury in these sediments were determined by sequential extraction method. The environmental similarity/differences were estimated by statistical tests and cluster imaging technique. The coastal post-tsunami sediments were characterized by higher contributions of organomercury species (median 14%) and mercury sulphide (75%) than the freshwater sediments (5.4-9.3% and 60-68%, respectively), however, the contributions of water-soluble fraction (0.6%) and mercury bound to humic matter (7.6%) in the former was lower. In the river sediments the contributions of water-soluble mercury and mercury bound to humic matter were: 2.0-5.7% and 16-24%, respectively. The contributions of acid-soluble mercury were generally very low, but relatively higher in the post-tsunami sediments (0.7%) than in the freshwater sediments (0.3-0.4%).