when pH and salinity increases, and they end up in the sediment (Åström and Corin, 2000; Åström et al., 2012). Sedimentation is presumably the main process influencing the fate and toxicity of metals in estuaries (Kuivikko et al., 2010). Precipitated metals in sediments may be bioavailable to benthic invertebrates via gastrointestinal tract and skin. Metals may also be redissolved from sediments to the aqueous phase if physical-chemical characteristics are altered or sediment is bioturbated.