Hexabromocyclododecanes in surface soil-maize system around Baiyangdian Lake in North China: Distribution, enantiomer-specific accumulation, transport, temporal trend and dietary risk

This study investigated the occurrence of hexabromocyclododecanes (HBCDs) in soil-maize system around Baiyangdian Lake. The total concentration of ΣHBCDs was in the order of industrial area > residential area > marginal area > Fuhe River estuary in soil. γ-HBCD was predominated in soils, roots and stems, while α-HBCD was the main diastereoisomer in leaves and kernels. Concentration of ΣHBCDs and three diastereoisomer concentrations in soils were significantly reduced and remained low level from 2018 to 2019. Selectivity enrichment of (+)α- and (-)γ-HBCD was found in soils, roots, stems and leaves, whereas only (+)β-HBCD dominated in stems. Most of the total root bioaccumulation factors (ΣRCFs) were less than 1.0, but no significant correlation was showed between translocation factors (TFs) and log K_ow. RCFs and TFs of enantiomers suggested (-)β- and (-)γ-HBCD were easily translocated from soil to roots, while (+)α-, (-)β- and (-)γ-HBCD tended to translocate from stems to leaves. Estimated daily intake (EDI) and of ΣHBCDs, diastereoisomers and enantiomers were all lower than the threshold value, while the Calculated margins of exposure (MOE) were well above the threshold value, which demonstrate the safe consumption of Maize around Baiyangdian Lake.