Bioaccumulation and toxicity of aluminium in the pond snail at neutral pH(+)

The low solubility of aluminium (Al) at neutral pH means that it largely ex ists as colloidal particulates in aquatic systems. However, the pond snail Lymnaea stagnalis accumulates significant amounts of Al following exposure to water containing added Al (up to 500 mu gl(-1)) at pH 7. This is accompa nied by depression of behavioural activity (locomotion, feeding) which subs equently recovers, suggesting tolerance to the metal. The presence of silic a ameliorates behavioural toxicity of Al, but does not prevent uptake of th e metal. In vitro studies using the isolated central nervous system demonst rate toxicity at the cellular level. Extracellular application of Al ( 100 mu M) led to membrane depolarisation, bursts of action potentials and actio n potential broadening. The chemical form in which Al is applied influences the extent of bioaccumu lation and toxicity. Detailed knowledge of its solution chemistry is theref ore essential.