Evaluating The Biodegradability Of Nitenpyram By OECD Testing Guidelines

Nitenpyram is an prominent pestcide to control Hemiptera insect,which is high efficienct,low toxic,systemic and no interaction resisitant to rice leafhoppers,planthoppers,aphids greenhouse,whitefly,worm and etc.Nitenpyram can eventually enter into water and natural environment by the ways of application,spraying drift,waste water treatment,agriculture sewage dischargement and atmospheric particles deposition.Therefore researching biodegradability of Nitenpyram is beneficial to kown the migration and transformation procession of Nitenpyram in the environment which can help us build theoretical foundation for controling pollution and protecting environment.OECD is an international organization who promotes the testing guidelines of chemicals that is widely acceptted and whose purpose is for management.The chemicals defined in the OECD testing guidelines include industry chemicals,pesticides,food additives and pharmaceuticals.In this paper,OECD testing guidelines209,301 and 302 are used to evaluate the biodegradation of Nitenpyram.1 In Activated sludge respiration inhibition test:?1?the 3h-EC₅₀0 of 3,5-dichlorophenol met the standards range 2²5mg/L for international comparation.?2?the 3h-EC₅₀0 of Nitenpyram>1000 mg/L,from which we can exclude the phenomenon that the low Nitenpyram biogradability percentage is caused by the high toxic to microorganism in activated sludge.?3?Different batch activated sludges collected from the same treatment plant in the same season,the EC₅₀0 of 3,5-dichlorophenol was changed widely from 5.25mg/L to2.82 mg/L.?4?the longer the toxic chemicals was exposured in the activated sludge,the lower the activity microorganism was in the activated sluge.the EC₅₀0 of3,5-dichlorophenol was changed widely from 5.25 mg/L to 9.51 mg/L.?5?Comparing gamma model with logostic model showed that EC₅₀0 calculated by the two models are almostly consistent.gamma model is more prominent which does not require compound concentration for 100%inhibitation,a lower solubility of the testing substance and less data.2 Four OECD ready biodegradation testing results of Nitenpyram are consistent which biodegradation percentage were less than 60%and does not reach the ready biodegradation testing level,indicated we should take the futher study of inherent biodegradation.3 Inherent biodegradability test-Zahn-Wellens Test biodegradation percentage for Nitenpyram is 16.5%<20%,indicated primary biodegradation process does not occur in aerobic aquatic environments.