[Toxic effects of hexavalent chromium on the growth of blue-green microalgae]

A standard method of algal bioassay for determining the toxicity of toxic chemicals was applied to the interaction between Cr(VI) and six blue-green microalgae. The 96h-EC50 of hexavalent chromium on the growth of Chlorella pyrenoidosa, Synechococcus, Spirulina maxima, Spirulina platensis, Selenastrum capriornutum and Scenedesmus quadricauda were 4.96, 6.50, 11.16, 11.74, 12.43 and 20.89 mg/L, respectively. The tolerance of the six blue-green microalgae to Cr(VI) was in the order of Scenedesmus quadricauda > Selenastrum capriornutum > Spirulina platensis > Spirulina maxima > Synechococcus > Chlorella pyrenoidosa. The sensitivity of these species to Cr(VI) might relate to the cell size, the structure of cell wall, as well as the redox reaction caused by the exudate or enzyme. X-ray absorption near edge structure(XANES) was used to study the accumulation and transformation of Cr(VI) in Chlorella pyrenoidosa.