ALUMINUM POLYMERIZATION - A MECHANISM OF ACUTE TOXICITY OF AQUEOUS ALUMINUM TO FISH

In this article a new theory is presented, whereby the process of alum inium polymerization is a mechanism of acute toxicity of aluminium to fish, as opposed to precipitation of solid Al(OH)(3) or cellular inter nalization of Al3+. Between pH 5.0 and 6.0, where toxicity seems most acute, conditions are favourable for Al polymerization. According to t he present theory, positively charged Al-hydroxides bind to negatively charged sites of the gill surface which act as polymerization nuclei. Growth of Al polymers on the gill surface and increased mucus secreti on cause severe clogging of the interlamellar spaces. This physical su rface effect leads to acute hypoxia. The overall mechanism of aqueous Al toxicity is explained in terms of more than one single process, whe re the most acutely toxic situation for the fish is during the initial phase of Al polymerization.