Accumulation of Agricultural Pesticides by Three Freshwater Microalgae

Abstract

Total amount of pesticide absorbed and accumulation rates of Microcystis aeruginosa (Cyanophyceae), Scenedesmus quadricauda (Chlorophyceae), and Aulacoseira granulata (Bacillariophyceae) exposed to different single and combination concentrations of the agricultural pesticides, CNP (p-nitrophenyl 2,4,6-trichlorophenyl ether), MEP [0,0-dimethyl 0-(3-methyl-4-nitrophenyl) thiophosphate], and ISP [isoprothiolane (C12H18O4S2)] were determined. Lipid analysis was carried out to evaluate the penetration of the pesticides into the cell. The highest total amount of pesticide absorbed and accumulation rates of the three microalgae were obtained upon exposure to different concentrations of ISP while their lowest values were obtained for MEP. The total amount of Pesticide absorbed and accumulation rates differ in the three experimental organisms. M. aeruginosa showed the highest values for all pesticides while S. quadricauda showed the lowest values. The accumulation rates of the three microalgae for a specific pesticide were greatly reduced in the presence of other pesticides in the medium. Results of the lipid analysis showed that ISP was detectable in the lipids of the three microalgae indicating that it can penetrate into the cells. CNP showed a greater affinity to the lipids of S. quadricauda and A. granulata not in M. aeruginosa. MEP did not penetrate into the three microalgal cells.