Polybrominated diphenyl ethers (PBDEs) in English freshwater lakes, 2008–2012

• PBDE concentrations are comparable to the limited data available for the Great Lakes.
• ΣBDE concentrations in water samples showed TSS dependence.
• ΣBDE concentrations showed seasonal trends: higher in colder than in warmer periods.
• Generally higher BDE-47:99 ratios in warmer than colder months.
• BDE-47:99 ratios decreased significantly with increasing TSS content of samples.

Concentrations of tri-to-hexa-BDEs were determined in water samples taken from 9 English lakes on 13 occasions between April 2008 and February 2012. Across all sites, concentrations of ΣBDEs in individual samples ranged from 9.2 to 171.5 pg L−1, with an average of 61.9 pg L−1. Notwithstanding the far greater use of the Penta-BDE commercial formulation in the USA, concentrations in this study are comparable to the limited data available for the Great Lakes. PBDE concentrations showed no evidence of a decline at any monitored location over the study period. This may be because this study commenced 4 years after the introduction of restrictions on the Penta- and Octa-BDE formulations. While concentrations normalised to water volume at the different locations were statistically indistinguishable; significant spatial variation was apparent when the data were normalised to total suspended solids (TSS) content. However, this spatial variation was not correlated with factors such as population density and lake catchment area, suggesting that concentrations of PBDEs in lake water in this study are a complex integral of numerous factors. BDE-47:99 ratios and concentrations of ΣBDEs respectively decreased and increased significantly with increasing TSS content. As TSS content was elevated in colder compared with warmer periods, such seasonal variation in TSS content appears a major contributor to the observed elevation of ΣBDE concentrations in colder periods, and higher BDE-47:99 ratios in warmer periods.