Toxicity of metals, Al, Cd, Co, Cr, Cu, Fe, Ni, Pb and Zn on microalgae, using microplate bioassay 1: Chlorella kessleri, Scenedesmus quadricauda, sc. subspicatus and Raphidocelis subcapitata (Selenastrum capricornutum)

Toxicities of Al, Cd, Co, Cr, Cu, Fe, Ni, Pb and Zn were tested using growth miniaturized algal bioassay with Chlorella kessleri, Raphidocelis subcapitata (= Selenastrum capricornutum), Scenedesmus quadricauda and Scenedesmus subspicatus. Toxicity hierarchy for all organisms, according to their mean values is: Cd> Co> Cr> Cu> Pb> Ni> Zn> Al> Fe. The sensitivity hierarchy is: Raphidocelis >Scenedesmus subspicatus > Chlorella > Scenedesmus quadricauda. The most toxic element was Cd, which was the first in toxicity hierarchy for all tested organisms. Cd has a gradual toxic curve, and has showed no stimulation, similar to Pb. Scenedesmus quadricauda showed a peak shape of growth curve with stationary phase about 300 h. Another algae showed prolonged and approximately stabile stationary phase in the period of 300-700 h, under PhAR 180 μE.m -2 . s -1 , (40 W.m -2 ) 30°C, and CO 2 supply ca 2% (v/v).