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Transport and fate of polybrominated diphenyl ethers in the Baltic and Arctic regions

image of Transport and fate of polybrominated diphenyl ethers in the Baltic and Arctic regions

In the last decades, concern has been raised regarding the use of polybrominated diphenyl ethers (PBDEs) due to its increased environmental occurrence and its possible toxicological impact in humans and wildlife. As a result, two of the commercial PBDE products have recently been banned within the EU, while the use of the third product (DecaBDE) is still approved. A dynamic, fugacity-based, regional multimedia fate and transport model (POPCYCLING-Baltic) has been used to assess the historical behaviour and the potential future fate of polybrominated diphenyl ethers (PBDEs), exemplifying different emission scenarios following the introduction of restricting measures. The past, current and future consumption and emission of PBDEs were estimated, and the environmental fate of individual compounds was modelled. The possible impact on the Arctic region is also discussed. Uncertainties in the estimates and data gaps were identified.

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Potential for long-range transport and possible impact on the Arctic region

The propensity for transport of PBDEs to Arctic regions may be studied using longrange transport models. Such an analysis has recently been performed by Wania and Dugani (2003), thus it was considered unnecessary to redo the assessment. Instead, the findings by Wania and Dugani (2003) are utilised to analyse the possible implications they would have in the context of the current project. Wania and Dugani used four multimedia fate models, particularly designed for assessment of long-range transport potential of organic chemicals, to assess the potential for long range transport LRT of polybrominated diphenyl ethers. It was concluded that the four models (TaPL3-2, ELPOS-1.1.1, Chemrange-2 and GloboPOP-1.1.), which all calculate a numeric indicator of long-range transport potential, gave comparable results. The model predictions suggest that congeners of intermediate degree of bromination are more efficiently transported long distances than are low and high brominated substances. This is explained in terms of the interaction between the two processes of atmospheric partitioning and degradation. Congeners of very low bromination degree are more rapidly degraded in the atmosphere, whereas heavier compounds tend to deposit to terrestrial or marine surfaces closer to source regions. Thus, the congeners most likely to be transported to the Arctic environment, are PBDEs of low to moderate halogenation, e.g. tetra and pentaBDEs, and this LRT potential would be of the same order of magnitude as for highly chlorinated PCBs. In this assessment, that would imply LRT for BDEs 47 and 99, but not 209. The model predictions described in Wania and Dugani (2003) are supported by monitoring data in Arctic air (Alaee et al. 2000.), in marine mammals (Ikonomou et al., 2002) and in sediments from Greenland lakes (Malmquist et al., 2003). Considering the emission scenarios assessed here, measures taken to prevent the use of penta and octaBDE in Europe should contribute to reduce the PBDE levels observed in the Arctic environment. However, environmental levels in the Arctic are also likely to be controlled by emissions in other parts of the globe.

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