Trends in hexabromocyclododecanes in the UK and North America

Abstract

Water samples (n = 107) taken from nine English freshwater lakes from a mix of urban, rural, and remote locations on 12 occasions between August 2008 and February 2012, and archived suspended sediment samples (n = 39) collected over the period 1980–2012 at the mouth of the Niagara River in Lake Ontario were analysed to assess the temporal trends in contamination by the three main hexabromocyclododecane (HBCD) diastereomers (α-, β-, and γ-HBCD). HBCDs (45 to 890 pg L−1, n = 107) were generally equally distributed between the operationally defined freely dissolved and particulate phases in English lake water. Concentrations of HBCDs declined over the sampling period with half-lives of 5.1 years in English water, with a significantly decreasing trend also observed for Niagara River suspended sediments (NRSSs). With respect to seasonal trends, significantly higher concentrations were found in colder compared to warmer periods at 5 out of 9 English lakes, while NRSSs in this study revealed no statistically significant seasonal trends. The maximum HBCD concentration in NRSSs was about 3 orders of magnitude lower than those detected in English lake water, which is plausible given the greater per capita use of HBCD in Europe than North America. While γ-HBCD was consistently dominant (35–86%; mean = 56%) in English lake water samples, and dominated in NRSSs collected prior to 2002 inclusive (13–100%, mean = 73%), the abundance of γ-HBCD was significantly lower (3.5–37%; mean = 23%) in NRSSs from 2003 onwards.