Determination of heavy metals distribution in the anoxic sediment slurries by chemical sequential fractionation.

An analytical procedure involving chemical sequential fractionation was used for quantification of partitioning of some metals (Cu, Cr, and Cd) in anoxic sediment slurries (10 or 20% w/v) into six fractions. These fractions include exchangeable, bound to carbonate, easily reducible, moderately reducible, bound to organic, and residue fractions. Low amounts of Cu (10-11%) and moderate amounts of Cr (38%) and Cd (38-39%) were retained as the easily reducible and moderately reducible fractions which represented the mobile forms of metals in the sediments. The amendment of different amounts (20 or 100 mg/liter) of metals into the anoxic sediment slurries (10% w/v) resulted in a different percentage distribution of metals into six fractions. The amount of Cd in the carbonate fraction increased significantly after Cd amendment. The percentage of Cu or Cr in the easily reducible and moderately reducible fractions increased, while those in the residual fraction decreased as the amount of Cu or Cr amended into the sediment slurries increased.