THE INFLUENCE OF PH ON ALUMINUM TOXICITY IN THE PHYTOPLANKTON SPECIESMONORAPHIDIUM-DYBOWSKII AND MONORAPHIDIUM-GRIFFITHII

The toxicity of aluminum on the phytoplankton species Monoraphidium gr iffithii and M.dybowskii (Chlorophyceae) was investigated. At pH 6.8 a nd low humus concentration, the growth of both species was reduced at 100-200 mu g Al/l, whereas at pH 4.8 only the growth of M. griffithii was affected. The toxicity on the two species showed different relatio ns to the ps-value. The results, supported by analyses of Al-fractions - total acid soluble, total monomeric and none-labile monomeric Al - indicate that the Al-toxicity is species-dependent, and that aluminium , soluble at neutral pH-conditions, can be toxic to the phytoplankton.