Bioconcentration And Food Chain Migration Of Halogenated Flame Retardants In Inner Mongolia Grassland Of China

Halogenated flame retardants(HFRs)are a kind of flame retardants containing halogen elements.HFRs are of great concern in the past few years due to their ubiquitousness in the environment and potential bioconcentration characteristics.HFRs have "three pathogenic effects"(carcinogenic,teratogenic and mutagenic)and can disrupt the endocrine system.This study takes Xilingole grassland in Inner Mongolia as the research area to analyze the pollution characteristics of polybrominated diphenyl ethers(PBDEs),new halogenated flame retardants(NBFRs:tetrabromo-p-xylene(pTBX),pentabromobenzene(PBBz),hexabromobenzene(HBB),pentabromotoluene(PBT)and pentabromoethylbenzene(PBEB))and Dechlorane plus(DPs)in grassland food chain.The purpose is to explore the bioaccumulation characteristics of HFRs in organisms and the migration law in grassland food chain.The results of this study can not only remind the environmental risk of persistent organic pollution in ethnic minority areas,but also provide data support for the prevention and control of organic pollutants in ethnic minority areas.This will help promote the sustainable development of the ecological environment in ethnic minority areas.The major results are as follows.(1)Except that BDE-209 does not have long-distance migration ability,PBDEs(BDE-28,BDE-47,BDE-99,BDE-100,BDE-153,BDE-154 and BDE-183)have long-distance migration ability.In the food chain composed of amphibians,reptiles and birds,high brominated PBDEs(BDE-154,BDE-153 and BDE-183)are more likely to be bioaccumulated and biomagnified,while low brominated PBDEs in mammalian food chain are more likely to be bioaccumulated and biomagnified,while human food chain has bioaccumulation and biomagnification effects on PBDEs.The distribution of PBDEs in sheep organs and tissues is affected not only by the function of organs and tissues,but also by the characteristics of PBDEs.Adipose tissue tends to bioaccumulate high brominated PBDEs,but muscle tissues and visceral organs mainly bioaccumulate low brominated PBDEs.The distribution of PBDEs in visceral organs is mainly affected by the transport of ovine serum albumin(OSA)and the metabolism of CYP3A24 enzyme.The distribution of PBDEs in adipose tissue and brain is mainly affected by their log Kow.(2)NBFRs(pTBX,HBB,PBT,PBBz and PBEB)can also be transported to Xilingole grassland through long-distance migration.pTBX is more likely to be bioaccumulated and biomagnified in the food chain of amphibians,reptiles and birds,while PBT and HBB are more likely to be bioaccumulated and biomagnified in the food chain of mammals.This may be because these animals have different eating habits and metabolic patterns.The distribution of NBFRs in sheep visceral organs is affected by organ function and physical and chemical properties of NBFRs.Sheep adipose tissue can continuously bioaccumulate NBFRs.According to the concentration distribution of NBFRs in sheep organs and tissues and the binding ability with OSA and CYP3A24 enzyme,PBT,HBB and PBBz are easy to be bioaccumulated in sheep.Therefore,the environmental health risks of PBT,HBB and PBBz deserve further attention.(3)HFRs have different biomagnification trends through the grassland food chain,and dietary habits will affect the bioaccumulation of HFRs.PBDEs are dominant in the grassland food chain,but the proportion of NBFRs in sheep,weasels and cuckoos has increased to a great extent.This indicates that different types of animals have different abilities to bioaccumulate or metabolize PBDEs and NBFRs.For DPs,the food chain composed of amphibians and reptiles can bioaccumulate and biomagnify syn-DP.Mammals with lower trophic level are more likely to bioaccumulate and biomagnify syn-DP,but mammals with higher trophic level are more likely to bioaccumulate and biomagnify anti-DP.Sheep adipose tissue can bioaccumulate PBDEs and NBFRs,and there is no difference in their bioaccumulation by fat.The concentration of PBDEs and NBFRs in sheep visceral organs showed differences.The bioaccumulation ability of PBDEs in visceral organs was greater than that of NBFRs.The blood-brain barrier of brain could block the bioaccumulation of PBDEs and NBFRs.(4)Under low concentration level,the bioaccumulation capacity of HFRs in human hair may be stronger.There are gender differences in the bioaccumulation of HFRs in human hair,that is,female hair may be more likely to bioaccumulate HFRs.