Study On The Historical Pollution Characteristics Of Synthetic Pyrethroid In The Middle And Downstream Of The Yangtze River

The residue of synthetic pyrethroid pesticides was concerned by scientists with the rapid development of synthetic pyrethroid pesticides(SPs)in pesticide market.Sediment is a important sink of hydrophobic organic pollutants,therefore,sediment core is a effective tools of studying volutionary history of pollutants.Different volutionary history of SPs from different backgrounds were dicussed.The results show average concentration of Synthetic pyrethroids(SPs)in the study is 0.83-8.85 ng/g dw,and its range is 0.15-33.4ng/g dw.The concentration of SPs of East Chaohu Lake(ECH),West Chaohu Lake(WCH),LongGan Lake(LG)and DaGuan Lake(DG)are at the lower level of the world.The source of organic matter is similar to the source of SPs in ECH.There is a poor correlation between total organic carbon and concentration of SPs in WCH,which is result by complex sources of organic matter.There is also a poor correlation between total organic carbon(TOC)and concentration of SPs in LG.The source of organic matter is adverse to the source of SPs in core sediment of DG from 0 cm to-15 cm.In addition to TOC,the concentration of SPs is influenced by economic development,and type of land use.The most important three SPs in in the study are permethrin(27.46%),cypermethrin(22.56%),cyfluthrin(15.42%).Composition of SPs in ECH and WCH is much different,while it is similar between LG and DG.The historical pollution characteristics of SPs in ECH are greatly affected by the application of pesticides,precipitation,and the level of angricultural development.The historical pollution characteristics of SPs in WCH are greatly affected by precipitation,angricultural activities and urban activities.The historical pollution characteristics of SPs in LG and DG are greatly affected by angricultural activities.There is a similar characteristic of ECH and DG that concentration decreases with depth increases.There is a similar characteristic in WCH and LG that concentration increases with depth increases.?-cyhalothrin and fenvalerate were used in ECH during initial period of history of SPs,while cypermethrin and deltamethrin were used in ECH during later period of history of SPs.There is a similar composition of SPs in the medium floor and surface of ECH that several SPs have a important ratio on composition.There is a characteristic in the bottom of WCH that several SPs have a important ratio on composition and individual SP has a bigger ratio in the medium floor in WCH.There is a characteristic of LG that the kind of main SPs increases with depth decreases,which indicates human in LG used more kinds of SPs in later.And the main SPs used in LGare permethrin and cypermethrin.There is a characteristic of DG that the kind of main SPs decreases with depth decreases,which indicates human in DG used less kinds of SPs in later.And there is similar composition of SPs among every floor of DG except bottom.By two ecological risk assessment methods,we assess the ecological risk of SPs to the study area.The major risky SPs of Chaohu are cypermethrin and?-cyhalothrin and the major risky SPs of lakes of SuSong are cypermethrin and cfluthrin in the first ecological risk assessment method of Toxic units(TU)method.Cypermethrin has a higher ecological risk to all sites than permethrin,especially to lakes of SuSong,in the second ecological risk assessment method of Species sensitivity distributions(SSD)method.There is a high ecological risk of SPs in WCH in two ecological risk assessment method.