TOXICITY OF WATER-SOLUBLE FRACTIONS OF PETROL ON SOME FRESHWATER MICROALGAE

ABSTRACT

Petroleum hydrocarbons are common contaminants of water bodies particularly in areas where oil exploration and petroleum products are used. This study assessed the toxicity of water soluble fractions of petrol on Chlorella vulgaris and Scenedesmus obliquus. Petrol WSF was prepared into various concentrations as follows: 0%, 5%, 10%, 25%, 50%, 75% and 100%. These preparations were inoculated with the 5ml of the test microalgae and read at two-days intervals for 14 days using a 721 Visible Spectrophotometer. The results of the growth response showed better growth response for C. vulgaris than for S. obliquus at the same WSF concentrations. Both Chlorella vulgaris and Scenedesmus obliquus exhibited stimulatory growth response at lower concentrations (5%, 10%, 25% and 50%) while higher WSF concentrations (75% and 100%) were inhibitory to their growth. The concentration of TPH decreased from 23325.00µg/l in the 100% petrol WSF to 7699.98µg/l in the C. vulgaris 25% WSF of petrol, and 7759.91 µg/l in the S. obliquus 25% WSF of petrol at the end of the experiment. Based on the results of total petroleum hydrocarbon, the test microalgae were shown to have bioremediation potential. The oxidative biomarker activity for C. vulgaris and S. obliquus was not dependent on the concentrations of petrol WSF. Therefore, these species can be explored as potential candidates in bioremediation of oil-contaminated aquatic environments when the level of contamination is low.