Bioaccumulation And Transfer Of Organophosphorus Flame Retardants In Some Typical Animals From The Pearl River Delta

Organophosphorus flame retardants(PFRs)are widely used as flame retardants,plasticizers,and defoamer in electronics,building materials,textiles,and chemical industries.PFRs is an emerging organic pollutant with certain bioaccumulation and biotoxicity.Bioaccumulation and parental transfer are important for assessing the ecological and health risks of pollutants.Until now,the studies on PFRs in animals mainly focus on aquatic animals,while the researches on terrestrial animals and amphibians are limited.The reports on bioaccumulation,parental transfer,and metabolism of PFRs in animals are extremely rare.In this dissertation,the method of freezing-lipid precipitation,solid-phase extraction and gas chromatography-mass spectrometry was firstly established to determine PFRs in large amounts of biological samples with high lipid content.Secondly,the regional distribution and inter-species differences of PFRs in three freshwater fish species from the Pearl River Delta(PRD)were investigated,and the possible health risks of PFRs caused by the consumption of freshwater fish were also assessed.Thirdly,the bioaccumulation,metabolism,and parental transfer of PFRs in aquatic animals,frogs,and insects collected from an e-waste polluted site in Qingyuan,Guangdong were systematically studied;meanwhile,the effects of metamorphosis on PFRs accumulation in insects were also assessed.Under the optimal experimental conditions,the developed method exhibited a good lipid removal rate of up to 97%.The recoveries of twelve PFR targets(except TEP)ranged from 73%to 108%in spiked blank samples,and ranged from 56%to108%in spiked fish samples.The recoveries of the four surrogate standards in spiked blank samples and spiked fish samples were 90%-106%and 75-97%,respectively.The relative standard deviations of each analyte in three parallel samples were all less than 15%.The limits of detection and quantification for PFRs were 0.004-0.059 ng/g and 0.027-0.55 ng/g,respectively.The results demonstrated that this proposed method exhibited satisfactory lipid removal rate,accuracy,and reproducibility.It is suitable for the analysis of PFRs in large amounts of biological samples with high lipid content.The concentrations of total PFRs in mud carp,tilapia,and plecostomus in PRD were 2.3-16 ng/g ww,3.4-16 ng/g ww,and 3.5-30 ng/g ww,respectively.In general,TEHP,TCIPP,TCEP and TNBP were major pollutants,collectively accounting for about 90%of the total concentrations.Higher concentrations of PFRs were observed in the Pearl River and Beijiang River with greater urbanization and industrialization than those in the Dongjiang River and Xijiang River.The concentration and composition of PFRs in the plecostomus were obviously different from those in the mud carp and tilapia,which could be explained by their different habitats,feeding habits,and metabolic capacity.The estimated daily intakes of total PFRs from the consumption of freshwater fish for the adults and children in PRD were 17 ng/kg bw/day and 98 ng/kg bw/day,respectively,which were 3 to 4 orders of magnitude lower than the reference doses.Thus,the daily consumption of freshwater fish by local resident does not pose potential health risks associated with PFRs.The concentrations of total PFRs in all aquatic animals(including snakehead,catfish,mud carp,crucian carp,shrimp,carp,and Chinese water snake)ranged from0.92 ng/g ww to 34 ng/g ww.The concentrations of total PFR metabolites were 1.3-14 ng/g ww,which were slightly lower or comparable to those of their corresponding parent compounds,indicating the importance of monitoring PFR metabolites in organisms.The higher concentrations of PFRs were found in the fish liver tissues,which were mainly related to the lipophilicity.The bioaccumulation factors(BAF)and biota-sediment accumulation factors(BSAF)of PFRs in these aquatic animals were 3.6-1109 and 0.0063-2.6,respectively.Both log BAF and log BSAF were significantly and positively correlated with log K_OW.The biomagnification factors of PFRs in Chinese water snake ranged from 0.017 to 0.26,indicating no biomagnification effect.The total PFRs,TNBP and TPHP underwent trophic dilution in this aquatic food chain(shrimp-omnivorous fish-carnivorous fish),with the trophic magnification factors of 0.72,0.57 and 0.62,respectively.Biotransformation/or metabolism was proved to be an important reason for the inter-and intra-specific bioaccumulation of PFRs,as well as the trophic dilution of PFRs in the wild food chain.Significant differences in the concentration and composition of PFRs between the eggs and muscle of Chinese water snake were observed,which were mainly related to the differences in the maternal transfer efficiency of different compounds.A significant positive correlation between the maternal transfer efficiency of PFRs and log K_OW was found in Chinese water snake.The concentrations of total PFRs in the muscle tissues of black-spotted frog and bullfrog were 1.0-14 ng/g ww.The concentrations of total PFRs,TEP,TCEP and TCIPP in muscle tissues of these two male frog species were significantly higher than those in female frogs,while the concentrations of these pollutants in the liver and gonad tissues of female frogs were significantly higher than those of male frogs.The OLR values(concentration ratio,C_other/(C_other+C_liver))corresponding to the male frog tissues were significantly higher than those of female frogs,indicating that the male frogs had higher metabolic capacity for PFRs.The parental transfer of PFRs in frogs is sex-specific.When using muscle tissues as parental tissues,the maternal transfer efficiency of PFRs were significantly and negatively correlated with log K_OW in female frogs,while the paternal transfer efficiency of PFRs were parabolic correlated with log K_OW in male frogs.These findings suggested that the metabolic transformation and parental transfer jointly affect the sex-specific accumulation of PFRs in frogs.The concentrations of total PFRs in six taxa of insects(litchi stinkbug,butterfly/moth,grasshopper,dragonfly,water scavenger beetle,and shining leaf chafer)ranged from 2.3 ng/g ww to 89 ng/g ww.The composition patterns of PFRs varied among different insect taxa due to their different habitats and feeding habits.Unlike vertebrates at relatively high trophic positions(such as aquatic fishes and Chinese water snakes studied in this study),herbivorous insects(grasshopper larvae)showed biomagnification effects on most PFR compounds,indicating the importance of monitoring PFR exposure in organisms at low trophic positions.The four taxa of insects,including butterfly/moth,dragonfly,grasshopper,and litchi stinkbug,were carefully divided into adults and larvae in this study.PFRs showed similar changes during metamorphosis in these four insect taxa,and the ratios of contaminant concentration in adults to larvae(ln A/L)were negatively correlated with log K_OW.This result indicated that PFRs had similar regulatory mechanisms during metamorphosis in these different insect species.