Biodegradation And Bioaccumuliation Of Triazophos By Algae

Pesticide Triazophos is extensively applied in China, but some important environment behaviors of Triazophos, such as microbial degradation, degradation mechanism and biosorption characteristics have not been reported until now. In order to comprehensively evaluate its environmental risk, the biodegradation and biosorption of Triazophos by three species of typical fresh algae were studied. The main conclusions obtained are listed as follows:In the first place, an analytical method on residual determination of Triazophos in algal medium and algal cells was established. The method for extracting and determining biodegradation product of Triazophos by Chlamydomonas reinhardtii was developed also.In the second place, the biodegradation of Triazophos in algae was studied. Three species of typical fresh algae, Chlamydomonas reinhardtii, Euglena gracilis, Synechococcus leopoliensis, were chosed as the experiment material in order to investigate their biodegradable abilities to triazophos. The results showed that the algae had the capability to degrade triazophos. At the initial concentration of 10 mg /L, the degradation rates by the former three species of algae were 35.3%, 44.6%, 9.8%, respectively, after 8 days of incubation. The order of the degradation rates was E. gracilis> C. reinhardtii > S. leopoliensis. Triazophos degradation by E. gracilis could be estimated by the first-order kinetic equation (R~2=0.983). However, it fitted to the second-order kinetic equation by C. reinhardtii and S. leopoliensis (R~2=0.998, 0.928).Finally, the bioaccumulation of Triazophos in the thre algae described above was studied, too. The results showed that bioaccumulation of triazophos could reach equilibrium instantly. At the initial concentration of 10 μg/ml, the corresponding bioaccumulation amounts of the three algae were 63.2 , 88.0 and 45.4μg/g.