Influence of the Sediment/Water Interface on the Aquatic Chemistry of Heavy Metals.

摘要

The mechanisms controlling the transport of three heavy metals: cadmium, chromium, and silver, in natural water systems are evaluated following a review of the scientific literature and laboratory studies of adsorption/desorption behavior and the interaction of these metals with phytoplankton. In fresh water, chromium as chromate is not appreciably taken up by model inorganic or organic particulates, but after reduction to Cr(III) is rapidly and irreversibly taken up by clay particles, hydrous iron oxide and phytoplankton. Cadmium and silver are more reversibly adsorbed by clay particles, are strongly adsorbed by hydrous manganese oxide, and are concentrated by phytoplankton. Once a part of reducing bottom sediments, the availability of all three metals to the aqueous phase is further reduced so that they are not released by short term resuspension. With prolonged resuspension of anoxic sediments some cadmium may redissolve, but chromium and silver will remain in the solid phase. (Author)