Environmental Behaviors And Exposure Risks Of New Flame Retardants In Surface River Sediments From The Yellow River Delta

With the development of society and technology,flame retardants(FRs)are widely used as chemical additives in consumer products which are closely related to people’s lives.At the same time,the research on the environmental fate and human exposure risk assement have also aroused great attention all over the world.Flame retardants generally do not form chemical bonds with polymers in consumer products,which also leads to their easy release into the environment.Due to the high hydrophobicity,flame retardants tend to accumulate in sediments.These compounds in the sediment could be ingested by inhabiting organisms and amplified in the food chain,ultimately lead to potential exposure risks to humans.This study collected and analyzed 31 river surface sediment samples from the Yellow River Delta,which is one of the six major estuary deltas in the world.The concentration levels and spatial distributions of emerging flame retardants-polybrominated diphenyl ethers(PBDEs),decabromodiphenylethane(DBDPE)and organic phosphates(OPEs)were studied,and their potential exposure risks were evaluated.The results show that the average concentration of PBDEs in the surface sediments of rivers is 18.33(range:not detected(nd)-122.27)ng/g.And the average concentration of BDE209 was 18.22(range:nd-122.16)ng/g,the concentration of BDE209 in the detected monomers reached more than 94%of PBDEs.The average DBDPE concentration is 18.38(range:nd-114.20)ng/g.In the analyzed samples,the ratio of the average concentration of DBDPE to BDE 209 was1.01,indicating that DBDPE in the investigated area was at the same level as BDE209.In addition,the average concentration of OPEs is 37.60(range:18.44-59.94)ng/g.The average concentration of OPEs has been higher than DBDPE and PBDEs,indicating that OPEs are widely used as alternative flame retardants after severe restrictions on brominated flame retardants.From the analysis of monomer composition,TCIPP is an important component of OPEs,with a concentration of up to 43%.The concentration of chlorinated OPEs(TCIPP,TCEP,TDCIPP)accounts for up to 61%of OPEs,which may be related to the difficult degradation of chlorinated OPEs.In terms of the spatial distribution trend,PBDEs and DBDPE in the estuaries were more than their upstream in the New Yellow River Channel and the Old Yellow River Channel.For OPEs,there is a tendency that the estuaries were larger than their upstream.Spearman correlation was used to analyze the relationship between PBDEs,DBDPE,OPEs and TOC,and the results showed that no significant correlation was found.In addition,a significant correlation was found between DBDPE and BDE209(R~2=0.775,P<0.01),TCIPP and TNBP(R~2=0.832,P<0.01),TCIPP and TCEP(R~2=0.644,P<0.01).This may be due to DBDPE being a potential replacement for BDE209,TCIPP also partially replaces TCEP which has biological toxicity.They have similar physical and chemical properties,so they have similar environmental fate.This study used the VLIER-HUMAAN soil exposure model to evaluate exposure risk of PBDEs,DBDPE,and OPEs in the analyzed sediment samples of the Yellow River Delta,which calculated the exposure of the Yellow River delta farmers through sediment oral exposure and skin contact exposure.And the non-carcinogenic risk assessment was performed on the intake of 31 sampling points of PBDEs,DBDPE and OPEs.The results indicate that the non-carcinogenic risk of the three types of flame retardants at current concentration levels is within acceptable levels in the investigated area.