Levels and distribution of hexabromocyclododecane and its lower brominated derivative in Japanese riverine environment

Hexabromocyclododecane (HBCD) and its lower brominated derivatives were measured in both surface water and sediment samples from three Japanese rivers; Tsurumi River, Yodo River, and Kuzuryu River. The concentration level of ∑HBCD (sum of α-, β-, and γ-HBCD) was in the order of Kuzuryu > Yodo > Tsurumi Rivers, reflective of the different emission sources for each basin. The highest ∑HBCD concentration (7800 ng g−1 dw) was detected in the sediment sample from the Kuzuryu River that receives effluents from textile industries, which use HBCD in flame retardant finishes. A different diastereomeric pattern of α-, β-, and γ-HBCD of each river was investigated, indicating the level of HBCD in these rivers is directly influenced by emission source. Enantiomer fractions of HBCDs in water and sediment samples were also determined. Racemic mixtures were observed in the water samples, whereas enantiomeric enrichment of (−) γ-HBCD and (+) α-HBCD was observed in the sediment samples. Some lower brominated HBCD derivatives such as pentabromocyclododecenes were detected in both the water and sediment samples, and their concentration ranged from below the detection limit to 15 ng L−1 and 20 ng g−1 dw, respectively.