Study On Quantitative Detection And Transformation Of Polybrominated Diphenyl Ethers In Chinese Mitten Crab

The development of industry and technology has promoted the rapid advancement of the social economy,accompanied by the generation of large amounts of chemical pollutants.The rise of the electronic and textile industry release a large number of polybrominated diphenyl ethers（PBDEs）into the environment.Nowadays,PBDEs has been detected in various water bodies,sediments and other environmental media,as well as in organisms,such as fish,chickens and mudsnails.Due to the characteristics of PBDEs of lipophilicity,persistence,accumulation and migration,they can adhere to suspended particles in aquatic ecosystems and afflux into the sediments through sedimentation.Under the effect of sediment accumulation and transfer,they can accumulate in aquatic organisms through ingestion way,tranfers and accumulates into higher trophic organisms through the food chain,and eventually pose food risks to humans at the top of the food chain.Here,in order to investageate the migration and bioaccumulation effects of PBDEs in aquatic ecosystems,Chinese mitten crab breeding system was seleced as the subject in this study,a quantitative detection method was established for deteming 8 common compounds of the environmental media and organisms in the breeding process,including BDE 28,47,100,99,154,153,183 and 209 the distribution characteristics and bioaccumulation levels of PBDEs were analyzed in the artificial pond of Chinese mitten crab.The main results were as following:（1）The method was established for the detection of eight PBDEs in water.In this study,effervescent-assisted dispersive liquid-liquid microextraction with solidification of the aqueous phase（EA-DLLME-SAP）was established for the preconcentration and determination of PBDEs in real environmental water samples by using Gas Chromatography-Tandem Mass Spectrometry（GC-MS-MS）quantitative analysis.1,1,2,2-Tetrachloroethane as the extractant was directly dispersed into the water samples combining with a large number of carbon dioxide bubbles generated from the acid-base reaction of acetic acid and sodium bicarbonate.Eight kinds of PBDEs have a good linear relationship based on this method,and the R² is not less than 0.9991.For the four types of water samples from tap water,lakes,rivers and reservoirs,the additional levels of BDE 28,47,99 and 100 were 1,10 and 100 ng·L^-1,and additional levels of BDE 153,154 and 183 were 2,20,and 200 ng·L^-1,and BDE209 for additional levels were 5,50,and 500 ng·L^-1.Then,the recovery rates ranged from 67.2%to102.6%,and the RSD was<8.5%.The method quantification limit of BDE 28,47,99 and 100 was 1 ng·L^-1,the BDE 153,154 and 183 was 2 ng·L^-1,and BDE 209 was 5 ng·L^-1.The intra-day and inter-day relative standard deviation were from 1.9%to 7.6%and from 1.8%to 8.2%,respectively.This method can meet the requirements of sensitive and rapid quantitative determination of PBDEs for environmental water samples with a sample volume of 5 mL and an extraction time of<30 s.（2）For sediment samples,a quantitative detection method for PBDEs was established.In this study,3.0 mL of n-hexane and dichloromethane mixture（v:v=1:1）as extract solution vortex ultrasonic assisted extraction and silica gel purification on a composite column was used for sample pretreatment.Then,the concentrated extraction was detected by GC-MS-MS with internal standard quantitative technology.The additional levels of BDE 28,47,99,100,153,154 and 183 were 10,100 and2000 ng·kg^-1,and the additional level of BDE 209 is 500,5000 and 10000 ng·kg^-1,the recovery rates were 89.1-102.6%,and the RSD was 2.5-7.2%.In addition,the inter-day relative standard deviation was between 3.1%and 6.9%,and the intra-day relative standard deviation was between 2.5%and 8.5%.By optimizing the type of extraction solvent,the type and volume of elution solvent,this method is a technology with high extraction efficiency for detecting the concentrations of PBDEs in environmental sediment samples with 18 minutes shorter than the extraction time of the standard method.（3）Basing on the established detection methods for water,sediments and organisms,the distribution,bioaccumulation and biotransformation of PBDEs in the environment media and organisms were dynamically monitored in Chinese mitten crab artificial breeding ponds.The results showed that mainly four congeners in environmental sediments,and BDE 209 was the main pollutant component with the highest content of 2360.86 ng·kg^-1.The content of PBDEs in the water is below the detection limit.The major components of the early developmental crab were BDE209,154,183 and 47,and the contents levels were 36.41,8.64,7.88 and 1.76 ng·kg^-1,respectively.Seven components of BDE 154,209,183,47,153,28 and 99 were detected in mature crabs,and the residual concentration were 61.26,37.33,25.25,25.33,13.41,1.03 and 0.93 ng·kg^-1,respectively.The crab in different developmental stages had a different distribution levels of PBDEs.The early developmental crab was dominated by medium-brominated and high-brominated compounds（BDE 209,183and 154）,while mature crab might migrate and transform with biological metabolism during the growth of crabs,resulting in low bromided compounds,because the content of PBDEs increased,especially for BDE 47 and 154.Regard to the feed,the mainly pollutant component was BDE 209,and the average content in pellets and corn feed were 1700.66 and 126.81 ng·kg^-1,respectively.Among other organisms in the aquaculture system（mudnails and aquatic plants）,main pollution compounds were BDE 209,and the content levels were 435.54 and 59.82 ng·kg^-1,respectively.Through the comparison of homologous components and the analysis of pollutant content,the pollution of PBDEs in artificial breeding environment of Chinese mitten crab was similar to the level of PBDEs in sediment and pellet feed.That is,BDE 209pollution was the most serious,accounting for 89.15%of the total pollution content level of∑₈PBDEs.Chinese mitten crabs and mudsnails,could accumulate PBDEs in aquaculture systems,but these animals had a higher bioaccumulation factor（0.31 to1.14）for low-bromine compounds（BDE 47）,while aquatic plants have no obvious enrichment effect on high-bromine and low-bromine compounds.In summary,the total input of pollutants in the Chinese mitten crab breeding environment was much higher than the detected concentration in aquatic organisms,and particulate feed and sediment were the main ways to cause PBDEs pollution in the environment.However,pollution of PBDEs in mature crab was related to many factors such as sediment,feed and snails.