Spatial trends of methoxylated polybrominated diphenyl ethers and suspect screening for brominated natural products in marine sediments and island soils

Brominated natural products (BNPs) are widespread in marine environment and the fates of BNPs in marine sediments and island soils are unclear. Herein, the level, compositional profile, and spatial distribution of methoxylated polybrominated diphenyl ethers (MeO-BDEs) and suspect screening for other BNPs in marine sediments and island soils from mangrove, the Pearl River Estuary, South China Sea, and Arctic were explored. The average levels of ΣMeO-BDEs in marine sediments and island soils were 486 ± 95.3 and 725 ± 197 pg/g dry weight, respectively. The highest MeO-BDE concentrations were seen in mangrove sediments and their concentration from the other three sampling regions showed an increase trend from nearshore to offshore. Sediments from the South China Sea and Arctic exhibited predominantly natural occurring MeO-BDEs, while MeO-BDEs in mangrove and estuarine sediments mainly came from biotransformation of polybrominated diphenyl ethers. The distribution of MeO-BDEs in island soil samples revealed marine-to-terrestrial (island) biological transport pathway via seabirds. Nine BNPs, including three bromocarbazoles, five bromophenols and one dimethoxy-tetrabromobiphenyl were identified in sediments and island soils by a suspect screening method. Bromophenols are important precursors in formation of MeO-BDEs and dimethoxy-tetrabromobiphenyl are the transformation byproducts of bromophenols during MeO-BDEs biosynthesis. These findings provide critical insights into the source and fate of MeO-BDEs in marine environment and their ecological risks should be further explored. • Spatial distributions of MeO-BDEs were investigated in marine sediments and island soils. • Mangrove sediments had higher concentrations of MeO-BDEs. • Sediments from the SCS and Arctic exhibited predominantly natural occurring MeO-BDEs. • The distribution of MeO-BDEs in island soils revealed marine-to-island biological transport pathway via seabirds. • Nine brominated natural products were identified in sediments and island soils by a suspect screening method.