Bioaccumulation, trophic transfer and suspect screening for methoxylated brominated compounds in a tropical marine food web.

Methoxylated brominated compounds are widespread in the marine environment, yet their marine biogeochemical behavior remains poorly characterized. Herein, bioaccumulation and biomagnification of methoxylated polybrominated diphenyl ethers (MeO-PBDEs) and suspect screening for other methoxylated brominated compounds were explored in marine biota collected from the Xisha Islands, South China Sea. The concentrations of ΣMeO-PBDEs in marine fish and seabirds ranged from 2.87-17919 and 73.3-557 ng/g lipid weight (lw), with mean values of 944 ± 267 and 265 ± 82.8 ng/g lw, respectively. MeO-PBDEs in marine fish were mainly derived from natural biosynthesis. The average biota-sediment accumulation factors of 2'-MeO-BDE68, 6-MeO-BDE47, 4'-MeO-BDE49, 4-MeO-BDE42 and 5-MeO-BDE47 were all higher than 1, confirming sediment-derived bioaccumulation of these MeO-PBDE congeners in demersal fish. The biomagnification factor values of 6-MeO-BDE137 and 3-MeO-BDE47 based on quantitative fatty acid signature analysis were both greater than 1 in three seabird species, indicating high biomagnification capacities of these two MeO-PBDEs in seabirds. 6-MeO-BDE47, 6-MeO-BDE137 and 3-MeO-BDE47 showed significant trophic magnification, indicating that accumulation of the three MeO-PBDEs increased with trophic levels in the tropical marine food web. Seven new methoxylated brominated compounds including one Me-MeO-triBDE, three diMeO-PBDEs, two chlorinated diMeO-PBDEs and one diMeO-tetraBB were identified in marine biota by suspect screening. This study highlights bioaccumulation and trophic transfer of MeO-PBDEs in the tropical marine food web and the ecological risks of seven novel methoxylated brominated compounds in marine biota are needed to further evaluate.