A Berghof MWS-2 brand microwave digestion system was used to digest sediment samples for determination of pseudo-total metal content, as well as the residual fraction of the extraction procedure. Dried, fine sediment (0.5 g) were placed in advanced composite vessels and digested with a mixture of concentrated HNO3 (5 mL) and HCl (15 mL) (Davidson et al., 1998).