The Toxic Effects of Lindane via the Impact of pH and Dissolved Organic Matter on Microcystis aeruginosa

Abstract

The toxic effects of Lindane (γ-BHC) on Microcystis aeruginosa were studied under lab culture conditions. Total protein levels, as well as malondialdehyde (MDA) levels and superoxide dismutase (SOD) enzyme activity, in algal cells, were determined after exposure to different concentrations of Lindane. The bioaccumulation of Lindane, as well as the influence of pH and dissolved organic matter (DOM) on the toxic effects, was also evaluated in algal cells. The growth of M. aeruginosa was inhibited by the Lindane treatment (96 h), resulting in a 50% maximal effect (EC50) concentration of 442 μg/L. In addition, the lowest observed effect concentration (LOEC) was found to be 120 μg/L; the no observed effect concentration (NOEC) was found to be 60 μg/L, and the maximum acceptable toxicant concentration (MATC) was 85 μg/L. With increasing concentrations of Lindane and exposure time, M. aeruginosa growth was significantly inhibited; in addition, the total protein levels and SOD activity significantly decreased. MDA concentration, however, showed an insignificant increase after 96 h. Lindane has the potential for bioaccumulation in algal cells with a bioconcentration factor (BCF) of 340. Furthermore, the toxic effects of Lindane on M. aeruginosa were influenced by environmental factors, such as pH and DOM. The toxic effects decreased with increasing pH and humic acid concentrations. Ultrastructure cell images were used to depict Lindane-induced apoptosis.