Short term and long term studies on individual and combined toxicities of copper, zinc and lead to Scenedesmus quadricauda

Abstract

The toxicity of three metals (Cu, Zn, Pb) individually and in combination in a short term study (photosynthesis) and a long term study (growth) of a freshwater green alga, Scenedesmus quadricauda, was investigated. The relative metal toxicity to S. quadricauda was Cu > Zn ⪢ Pb, which corresponds with their respective electronegativities. This order was observed for both short term and long term studies. Specific individual and multiple heavy metal toxicities differed between short term and long term studies. Primary productivity was more sensitive to low concentrations of individual metals. Interactive effects between Cu, Zn and Pb were also assessed. In general, metal mixtures behaved antagonistically to photosynthesis. Both antagonism and synergism between Cu, Zn and Pb were observed to growth of S. quadricauda, although synergistic effects seemed to predominate.