The presence of polybrominated diphenyl ether (PBDE) flame retardants in total deposition (wet + dry) was assessed with the simultaneous use of three bulk samplers during a 2 week period. The particle associated and the 'dissolved' phase were separated during sampling. Volume weighted mean (VWM) concentrations of SigmaPBDE (9 congeners) in rain were 209 pg l(-1). Total deposition rates were 2 +/- 1 ng SigmaPBDE m(-2) day(-1). The total PBDE deposition was dominated by decaBDE(209) and thereafter 2,2'4,4'-tetraBDE(47) and 2,2'4,4',5-pentaBDE(99). Concentrations of particle associated and 'dissolved' PBDEs in total deposition were used to calculate filter/adsorbent ratios (F/A). We found that 65 +/- 18% of the total PBDEs were particle associated. Low F/A ratios for higher brominated congeners (Br > 5) were observed. This is contradictory with predictions based on the PBDEs' physico-chemical properties and was attributed to sampling artefacts, such as particle size distribution, and/or non-equilibrium processes. There was a negative relationship between the particulate SigmaPBDE concentration and rain volume suggesting a dilution effect and the importance of particle scavenging for wet deposition of PBDEs. (C) 2002 Elsevier Science Ltd. All rights reserved.
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