Changes in extractable metal concentrations during storage of surface water samples containing sediments

Changes in metal concentrations during storage of acidified water samples were studied. Water samples with high concentrations of suspended sediment were collected from the Fraser River, British Columbia. These samples were analyzed for ''extractable'' metals, which are defined to be the dissolved metals plus those metals extracted from suspended sediment by dilute mineral acid. Concentrations of extractable Cu, Fe, Pb, Zn, Ni, Co, Mn, and Cd we were determined over time. Metal concentrations in these water samples were not stable and showed significant increases throughout the storage period. These results suggest that the extractable metal technique is inappropriate for the analysis of water samples containing suspended sediment.