Plastic Pollution And Bioaccumulation Of Organic Pollutants In The Environment And Biota Of The Xisha Islands

The invention of plastics brings great advantages and convenience to human civilization due to their durability,flexibility and low production costs.The rapidly increased demand and production of plastic have become a global environmental issue.Due to physical wave forces,hydrolysis and ultraviolet radiation,plastic fragments will slowly break down into microplastics in the marine environment.Microplastics can be a vector for toxic chemicals in marine organisms.Those chemicals include plastic additives(e.g.,emollients,flame retardants,antimicrobials)and environmental contaminants adsorbed on their surface(e.g.,persistent organic pollutants(POPs),hydrocarbons,heavy metals).Microplastics alone and in combination with toxic chemicals can be transferred along the food chain through bioaccumulation and biomagnification processes,which in turn cause risk to human seafood safety.Most of the organic pollutants such as dichlorodiphenyltrichloroethane and its metabolites(DDTs),polybrominated diphenyl ethers(PBDEs),alternative brominated flame retardants(ABFRs),dechlorane plus(DP),and organophosphate esters(OPEs)are of persistence,long-range transport,bioaccumulation,and potential toxicity.Therefore,the research on their environmental occurrence and behavior has become an important issue worldwide.Due to the rapid urbanization and industrialization of the countries surrounding the South China Sea,the plastic waste generated by these countries is considered as potential sources of plastic waste in the South China Sea.The South China Sea is also recognized as a "hot spot" of organic pollutants.In this paper,the Xisha Islands in the South China Sea was taken as the research area to study plastic pollution and the distribution of organic pollutants in the environment of the Xisha Islands.The main findings are as follows:(1)Mesoplastics(95 items/kg,dry weight of sand)and microplastics(576 items/kg,dry weight of sand)were detected on the beach of Yongxing Island.The predominant color,shape and chemical composition of microplastics were transparent(49%),fragment(81%)and polypropylene(88%),respectively.9 individuals of OPEs,13 individuals of PBDEs,BTBPE,DBDPE,syn-DP and anti-DP were detected in plastic debris(mesoplastics and microplastics)and stranded foams.DDTs were not detected in all plastic debris.Except for OPEs and BDE 209,the detection frequency of other compounds were very low.OPEs were the main organic pollutants with a maximum concentration of 17000 ?g/g.TCEP and TCPP were the main OPEs in most plastic samples,and BDE 209 is the dominant congener of PBDE.The concentrations of ?OPEs,?PBDEs,?DP and DBDPE in the foamed PS sample(< 5 mm)were much lower than that in the stranded foam samples(> 5 cm),indicating large amounts of pollutants were released into the environment during foam plastics broken into microplastics.The high concentrations of organic pollutants in plastic samples may be derived from plastic additives.The high levels of additives in plastics are an important source of organic pollutants on the island.(2)56 plastic debris were detected in birds from Xisha Islands,and 93% of them were microplastics.The main color,shape and material of plastic debris are blue,thread and PP-PE,respectively.DDTs were the dominant organic pollutants(7.4-19000 ng/g)in birds,accounting for 66-99% of the total organic pollutants.BDE 47,BDE 153 and BDE 209 were the main PBDE congeners.BTBPE and DBDPE were the predominant compounds of ABFRs.anti-DP and p,p?-DDE were the main components of DP and DDTs,respectively.One-way analysis of variance showed that the concentrations of p,p'-DDE and most PBDEs in red-footed boobies were significantly lower than other birds,which can be attributed to different sources of organic pollutants in different habitats.The higher DBDPE abundance in red-footed boobies was most likely attributed to ingestion of microplastics.(3)DDTs were the predominant pollutants in marine fishes,accounting for 56-74% of the total organic pollutants.p,p'-DDE was the main compound of DDTs;BDEs 47,66,206 and 209 were the dominant PBDE congeners;PBT and DBDPE were the important components of ABFRs;anti-DP was the main isomers of DP.The concentrations of DDTs,PBDEs,ABFRs and DP were generally low in the three marine fishes.One-way analysis of variance showed that no significant difference between the concentrations of organic pollutants in these marine fishes.The daily consumption of these fishes from the waters near Yongxing Island could not pose a health risk of organic pollutants to local residents.