Effects of benzene, a water soluble component of crude oils, on membrane integrity and ionic content of the green alga Ankistrodesmus falcatus var. mirabilis

Experiments were devised to investigate the effects of the aromatic hydrocarbon benzene on the membrane integrity of the green freshwater alga Ankistrodesmus falcatus var. mirabilis. The ability of cells to retain ions (e.g. calcium, chlorine, copper, magnesium, manganese and potassium) when exposed to benzene was used as a measure of cell membrane disruption. Cells were exposed to various dosages of benzene in the light and the dark. Samples removed at pre-determined time intervals were analyzed for the above elements using neutron activation analysis. It was found that, (at dosages greater than ~24 umoles benzene per μl−1 cell volume), the rate of loss of potassium and manganese was proportional to both the benzene dosage and the time of exposure, but not affected by illumination. However, although loss of potassium and manganese from cells was complete after 24h exposure to the highest benzene dosage used (48 μmoles. μl−1) only a fraction of calcium, chlorine, copper and magnesium had been lost. This suggests a difference in the degree that these elements are bound or free in the cells, and that loss of potassium and manganese from cells is a sensitive indicator of cell membrane damage.