This was because most of the Hg in the water was attached to particles of suspended sediment, hila, such as organic matter including metal oxides (Domagalski ples 2001) and these precipitated onto the sediment. In addition, the Hg in the sediments was strongly bound to S2 to form a highly insoluble mercury sulfide (HgS) (Gabriel and Williamson, 2004 Hgr concentration