The effect of variations in aluminum and copper concentrations on the growth rate and enzyme activity of the green alga Scenedesmus quadricauda was investigated. The goal was to determine which chemical species control the biological parameters. The computer program MINEQL (Westal et al 1976) was used to estimate chemical speciation. In the prevalence of both metals, algal growth rate and alkaline phosphatase activity could be correlated to cupric ion activity. The activity of isolated bacterial alkaline phosphatase was found to be a function of both total copper concentration and cupric ion activity. A model was developed to predicted the effects on alkaline phosphatase of perturbation in aquatic chemistry
