Three hundred pellets will be weighed into polytetrafluoroethylene bottles before 750 mL of aqueous solution was added, resulting in a pellet concentration on a mass basis. After a conditioning period of approximately 24 h, proposed concentrations of 5 μg/L of CuII and ZnII will be added from a 50-mL mixed stock that had been prepared by serial dilution of individual plasma emission standards in Milli-Q water. The contents of the reactors will then be orbitally agitated at 150 rpm for a period of 7 days at room temperature, with subsamples of 50 mL of water and 20 pellets being extracted using a plastic bulb pipette and 1-mm nylon mesh respectively, after time intervals of 0.25, 0.5, 2, 6, 24, 50, 120 and 168 h. Water samples will be transferred to polypropylene centrifuge tubes and acidified to pH