The effect of acidification on the accumulation and toxicity of metals to freshwater invertebrates.

This paper reviews the literature to determine if lowered water pH (a) affects metal bioaccumulation in freshwater invertebrates, (b) enhances the toxicity of a given metal, and (c) increases waterborne metal concentrations to levels toxic to invertebrates. The elements considered are mercury, lead, cadmium and aluminum. The available evidence suggests that of these elements only mercury is biomagnified in aquatic foodchains. The bioaccumulation of all these elements is influenced by water pH, but data concerning invertebrates is meagre for mercury and lead. The effect of pH on mercury and lead toxicity to invertebrates is unclear and may be largely species specific. Cadmium toxicity is reduced by lower pH, while aluminum toxicity to invertebrates is markedly higher due to changes in aluminum speciation at low pH.