To simulate metal desorption within the acidic gut of bivalves, an experiment was conducted to measure metal desorption at pH 5.5 (the typical gut pH in bivalves; Owens,
1974) and at pH 8.0 (control, the pH of seawater). The labeled sediment was resuspended at pH 8.0 and pH 5.5 (prepared by the addition of dilute HCl) at a concentration of 5 mg l21.