| Pyrethroid pesticides are the new third generation pesticides by synthetic pyrethrins,due to the characteristic of high performance,broad-spectrum,safety and low-poison to people and livestock,pyrethroids have been widely used in aquaculture and agricultural pest control,which has a good effect for the control of common freshwater fish parasitic protozoa,anchors,fish lice,Chinese fir and other crustaceans parasite.Pyrethroids is one of the ideal alternatives for the traditional organic phosphorus and organic chlorine and other aquatic pesticides.With the extensive use of pesticides in agricultural production and aquaculture,a part of pesticides are likely to enter the water environment through surface runoff,rainwater scouring and domestic wastewater,which do serious harm to water environment and aquatic animals.In order to minitor the residues of pyrethroid insecticides in freshwater aquatic products,four representative pyrethroids including fenpropathrin,cypermethrin,fenvalerate and deltamethrin are detected by the gas chromatography with electron capture detector(GC-ECD).And the study determined the four kinds of pyrethrums in waters and fishes of the aquaculture waters(including ponds,rivers,lakes,etc.)in Hubei,Anhui,Sichuan and Chongqing.The accumulation and elimination rules of deltamethrin(DM)in Megalobra-ma amblycephala have also be studied.Besides,the possible pollution sources of pyrethroid pesticide residues in aquatic products were analyzed.The study was divided into four parts.The first part in the paper,a method was established for the determination of four pyrethroids including fenpropathrin,cypermethrin,fenvalerate and deltamethrin in freshwater,aquatic plantsand,sediments and the tissues of fishes by gas chromatography-electron capture detector(GC-ECD).The results showed that the linearity of the four pyrethroids was good from 1?g/kg to 100 ?g/kg and their regression coefficients were above 0.998.When the four kinds of pyrethroids were added in themuscle samples with the concentration of 2,4 and 8 ?g/kg,the recoveries were between62.3% and 113%,the precision was between 2.65% and 8.02% and the detection limit ranged from 0.2 to 1.0?g/kg,the quantification limit of the method was 2 ?g/kg.The average recoveries of four kinds of pyrethroids in water samples,aquatic plants and sediments were 81.10%~112.40%,80.46%~98.38% and 69.81%~120.90% respectively.The detection limit of fenpropathrin,fenvalerate and deltamethrin in water was0.005?g/L,cypermethrin was 0.015?g/L.The detection limit of four kinds of pyrethroids in aquatic plants and sediments were 1 ?g/kg and the limit of quantification was 2 ?g/kg,which indicated that the method had good reproducibility and high precision and could meet the relevant requirements of pyrethroid pesticide residues in freshwater aquaculture environment.In the second part,the pollution status of the freshwater aquaculture water and the pyrethroid pesticides in the Hubei,Anhui,Sichuan and Chongqing provinces were investigated by the multi-residue determination,and the contents,composition ratio and excess rate of them were also studied.The results demonstrated that the content of pyrethroids in aquaculture water in four provinces ranged from ND to 29.90 ng/L,the mean value was 3.10 ng/L and the detection rate of total pyrethroid was 7.14%,which was low.There were a certain degree of pyrethroid pesticides contamination in the freshwater aquatic products of the four provinces,which was not optimistic.Among the muscle samples,the concentration of pyrethrin was range from ND to 78.99?g/kg.The detection rate of the total permethrin was 55.36%,fenpropathrin was 41.44%,followed by deltamethrin,which was 14.41%.Cypermethrin was 11.71% and the fenvalerate was8.11%,which was the lowest.In addition,the residue of fenpropathrin was detected in27 of 111 muscle samples,which of 24.32% was higher than the specified levels.Deltamethrin in 3 samples of dosal muscle was exceed,which was 2.7%,the fenvalerate in 1 dosal and 1 abdominal muscle was exceed,which was 0.90%.While the cypermethrin did not appear excessive phenomenon.Therefore,the potential threat of pyrethroid pesticides on human and aquatic organisms can not be ignored.The distribution of pyrethroids in different type of water in four provinces were different.The pollution levels of the aquaculture waters is higher,the pollution degree of the lakes is the second,and the pollution degree of the rivers is the smallest.In the third part,after bath treatment of deltamethrin(DM)at the high doge of 5?g/L and the normal concentration of 0.44 ?g/L,we collected the tissues including theblood,liver,muscle,skin,gill,bravery and water at(18±0.5)? water temperature.The residue of DM in tissues at different time were detected by the gas chromatography and the data of drug concentration-time in blood were analyzed by pharmacokinetics software.The accumulation and elimination rules of DM in blood,gill,muscle,skin,liver and bravery of Megalobrama amblycephala were studied,which can intended to provide theoretic foundation to the residual problems in water environment and the quality security of the aquatic products.The DM could be accumulated by the tissues but the enrichment capacity of each tissue was different,the concentration levels of DM in tissues from high to low were the gill,plasma,liver,skin,muscle and bravery.The elimination half-lives T1/2 were 13.75 d(in liver),12.55 d(in muscle),12.55 d(in skin),5.35 d(in gill)and 3.28 d(in bravery).The concentration levels of DM in plasma,liver and gill tissues decreased significantly after 12 h and all the tissues of Megalobrama amblycephala could be reduced to less than(14.37±11.65)?g/kg(in liver)after 84 h.However,it can maintained for longer period in low level,which still can detected in skin,liver,gill and muscle after 768 h(32 d).The highest concentration of deltamethrin collected in the skin and muscle tissue was(10.0±5.39)?g/kg(4 h)and(4.32±3.12)?g/kg(48 h)respectively after the normal concentration,which are below the MRT of DM in fish muscle(30 ?g/kg).In the four part,the samples of aquatic plants and sediments in some parts of Hubei province of high pyrethrin content in the fishes were tracking monitored,and the environment,factories and population around the sampling sites were investigated to explore the sources of pollutants.Pyrethroid pesticides residues in water have a certain contribution to the residues in the fish,but their contribution rate was low,the residues in fish may mainly from feed,aquatic plants and sediments,which accumulated in the body through direct and indirect contacting to pyrethroid contaminants.In addition,pest control,daily mosquito control,landscaping and others needed pyrethroid pesticides and the residues entered the water and enriched in the fishes through the ways including surface runoff,the rain erosion and domestic wastewater. |
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