Natural organic acids: Their role in freshwater-acidification and aluminium speciation

Abstract

Samples containing humic substances, from an acidified area have been comared with corresponding samples from a less acidified area. The studies are based on an equilibrium-dialyzation, using artifical membranes. The waters are thoroughly caracterized before and after dialyzation. Results may suggest that the sulphur reacts with the humus, to form a "sulfonic humus" having a lower pK-value. Toxicity tests,using fish, suggest that dialyzed samples from acidified areas are more toxic than samples from less acidified areas.