Bioaccumulation And Trophic Transfer Of Typical Halogenated Pollutants In The Estuary-sea System

Halogenated organic pollutants contained halogenated elements such as fluorine,chlorine and bromine atoms,such as Poly-and perfluoroalkyl substances(PFAS)and Halogenated flame retardants(HFRs)studied in this research.Most of these compounds have properties of persistent organic pollutants(POPs).In the process of production and usage,these substances are inevitably transformed or discharged into the environment and organisms,which pose a threat to human health and ecological safety.In recent years,with the limited use of traditional substances(such as polybrominated diphenyl ethers,PBDEs),the kinds and production of new alternatives are increasing.As seafood is an important dietary source of protein for human body,there is a need to investigate the pollution characteristics of seafood and analyze the potential risks posed by pollutants.The Bohai Sea and Yellow Sea are important coastal areas for aquaculture and fishing of marine products,while there is a lack of research on the pollution characteristics of PFAS,HFRs and their substitutes PFECAs,DBDPE in the aquatic environment.This study systematically investigates the pollution level,characteristics and bioaccumulation of PFAS and HFRs in the Yellow Sea and Bohai Sea.This research explores the pollution characteristics of pollutants,bioaccumulation and trophic transfer behavior of pollutants in organisms,so as to provide a theoretical basis for scientific assessment of the ecological risk of pollutants.The main results of this paper include:(1)In order to reveal the distribution,bioaccumulation and trophic transfer behavior along the food chain of PFAS in aquatic ecosystem,food webs were constructed in Xiaoqing river estuary and Laizhou Bay,and PFAS pollution characteristics was systematically detected and analyzed.The results showed that legacy PFAS and substitutes were detected in various environmental media(water,sediment and organisms)in the two aquatic environment.PFECAs,substitute for PFOA,had been widely detected.HFPO-Tr A,PFMOAA and PFOA were the predominant compounds in samples.The total PFAS concentrations of benthic invertebrates were higher than that in fishes.PFMOAA was the main contributor in benthic invertebrates,especially in conch(reached up to 16700 ng/g dw).The total PFAS concentration of invertebrates followed the order: carnivorous > filter feeding,conch and sea snail(carnivorous)have specific enrichment characteristics of PFMOAA.The PFAS bioaccumulation may be the results of diet,exposure environment,properties of these substances,binding ability with protein,bioavailability,biological metabolism and transformation mechanism.The perfluoroalkyl chain length and functional groups have a certain impact on the bioaccumulation of PFAS,and the carbon chain length can be used as an influencing factor to predict the trophic transfer behavior.Long chain PFECAs(HFPO-Tr A,HFPO-Te A,PFO5 Do A)can be biomagnified along the food chain,while short chained PFECA(PFMOAA)have obvious bio-dilution potential.It is urgent to pay attention to the health risks posed by PFOA through seafood intake,the residents nearby were more vulnerable to be affected by hazardous threatens derived from PFOA in marine products.(2)The concentration,pollution characteristics,bioaccumulation and trophic transfer behavior of HFRs in the water environment of high pollution area(Xiaoqing river estuary and Laizhou Bay)were investigated.The concentration of ΣHFRs in organisms ranged from 5.90ng/g lw(conch)to 198 ng/g lw(mullet)in Xiaoqing river estuary,while in Laizhou Bay theΣHFR concentrations ranged from 19.6 ng/g lw in sea perch to 3360 ng/g lw in sea cucumber.BDE209 was the predominant compound in the estuary,whereas DBDPE was the main contributor to HFRs in the bay,followed by BDE209.Benthic invertebrates,especially bivalves and sea cucumbers,showed higher levels of BDE209 and DBDPE than fish.The HFR levels in the organisms of the two coastal zones were comparable to each other,although their concentrations in the estuarine water were one order of magnitude higher than those in the bay.Lower-brominated PBDEs could be biomagnified via trophic transfer,while the higher-halogenated HFRs showed biodilution potential.The bioaccumulation of HFRs might be attributed to the following factors: habitat,feeding habits,properties of compounds,bioavailability,and metabolism of compounds in organisms.The intake of PBDEs due to the consumption of aquatic food from this coastal aera may not constitute a significant threat to the human body.(3)The concentration level,spational distribution and characteristics of PFAS and HFRs in aquatic organisms from the Yellow Sea,Bohai Sea and North East China Sea were analyzed.The results showed that PFAS and HFRs were commonly detected in aquatic organisms from the Chinese coastal water.The pollution levels of organisms in the Bohai Sea were higher than that in the Yellow Sea,especially in Laizhou Bay.The ΣPFAS concentration of organisms ranged from 0.49 ng/g dw(silver pomfret)to 146 ng/g dw(Tongue sole).HFPO-Tr A,PFOA,C9-C12 PFCAs and PFOS were the dominant compounds in organisms from the Bohai Sea.C9-C12 PFCAs and PFOS were the main detected substances in the organisms of the Yellow Sea and North East China Sea.The PBDEs concentrations of organisms from Bohai Sea ranged from 435 to 6030 pg/g lw,and the total concentration range of alternative brominated flame retardants(a BFRs)is 3.83-1540 pg/g lw.While the concentration range of PBDEs in organisms from Yellow Sea and North East China Sea is87.8-3788 pg/g lw,and the total concentration range of a BFRs is n.d.-2100 pg/g lw.BDE-28,-47,-154,-153,-209,PBT and DBDPE were mainly detected in aquatic organisms.These two kinds of pollutants have their own distribution characteristics in different organisms(interspecific differences),which may be related to their feeding habits,habitat and metabolic mechanism of organisms.Considering the habitat of fish,the total concentration of these two pollutants in pelagic fish(except silver pomfret and Japanese Butterfish)is generally higher than that of benthic fish.According to the estimation of fish PFAS and PBDEs intake by human body,the EDI of pollutants ingested by local residents through eating seafood is low,and the exposure risk of eating seafood is low.(4)Estuary-bay is a sensitive and unstable zone in land-sea interaction and is susceptible to the effects of high-intensity human activities,in which physical,chemical,biological and geological processes are coupled and changeable.The concentration level of organic pollutants in various environmental media in the estuary with high organic matter load is relatively high.From the estuary to the sea,the pollutants showed a distribution trend from high to low,and the concentration level of pollutants in organisms from the Bohai Sea,Yellow Sea and North East China Sea is relatively low.Therefore,we need to focus on the ecological environment of estuary-bay.