The effects of acidification on the geochemistry of Al, Cd, Pb and Hg in freshwater environments: a literature review.

Acidification of freshwater environments (terrestrial, surface water, and freshwater sediment) can significantly affect the geochemistry of Al, Cd, Pb and Hg; for example, metal mobility within soils (Al, Cd), the relative distribution of dissolved metal species (Al, Cd, Pb, Hg), and the sedimentation rate of metals in standing water bodies (Cd, Pb) can be altered by acidification. In this critical review of the literature over the last decade concerned with the interaction of acidification with these four metals, we have attempted both to provide an assessment of the current state of knowledge in this field and to emphasize those areas where significant progress has been made since the possible implications of environmental acidification on metal geochemistry became widely appreciated in the late 1970s. We have also indicated those areas which we feel are most in need of further research.