Tetrabromobisphenol A and hexabromocyclododecanes in sediments and biota from two typical mangrove wetlands of South China: Distribution, bioaccumulation and biomagnification

Tetrabromobisphenol A (TBBPA) and hexabromocyclododecanes (HBCDs) were examined in sediments and biota species from two mangrove wetlands of the Pearl River Estuary (PRE) and the Jiulong River Estuary (JRE), South China, to investigate their distribution, bioaccumulation and biomagnification in mangrove food webs. Levels of TBBPA and Sigma HBCD (sum of alpha-, beta- and gamma-HBCDs) ranged from 0.003 to 0.31 and not detected (nd) to 1.11 ng/g dry weight in the sediments, and from 0.56 to 22.1 and nd to 56.3 ng/g lipid weight in the biota species, respectively. gamma-HBCD was the major diastereoisomer in the PRE sediments, while alpha- and gamma-HBCDs predominated in the JRE sediments. In contrast, alpha-HBCD was dominant in the biota. Mean enantiomeric fractions (EFs) of alpha-, beta- and gamma-HBCDs in the sediments all followed the trend of JRE > racemic standard > PRE. A significant enrichment of (-)-alpha-HBCD was found in the biota (p = 0.04), with EFs in the range of 0.297-0.485. Bioaccumulations were seen for TBBPA and alpha-HBCD as their biota-sediment accumulation factors (BSAFs) were greater than 1. (-)-alpha-HBCD had significantly greater BSAFs than (+)-alpha-HBCD (p = 0.04), indicating the preferential bioaccumulation of (-)-alpha-HBCD. Biomagnification factors (BMFs) of TBBPA ranged from 0.83 to 1.51, which varied among feeding relationships and mangroves. Positive relationships were found between TBBPA concentrations and trophic levels of the biota species with trophic magnification factors of 2.17 for the PRE and 1.22 for the JRE, suggesting that TBBPA biomagnifies in the mangrove food webs. No biomagnifications were observed for Sigma HBCD, alpha-HBCD and its enantiomers. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

The study found variations in the distribution and bioaccumulation of TBBPA and HBCDs in sediments and biota species from two mangrove wetlands in the Pearl River Estuary and the Jiulong River Estuary. Levels of TBBPA and HBCDs differed significantly between sediments and biota, with differences in the predominant diastereoisomers observed.