Sammendrag
Ambient air is among the core media selected for the sampling and analysis of Persistent Organic Pollutants (POPs) under the Stockholm Convention. Ambient air also provide useful information for (i) studies of global transports of POPs, and (ii) atmospheric sources and source regions. Yet, existing data on POPs in air based on active air sampling remain scarce and mainly limited to industrialized regions in the northern hemisphere. The primary objectives of this study were to (i) monitor concentrations of selected POPs in air outside West Africa, and (ii) to evaluate sources and source regions affecting measured concentrations. For this purpose, an active high-volume air sampler was installed on The Cape Verde Atmospheric Observatory (CVAO: 16.848°N, 24.871°W), a World Meteorological Organization (WMO) global station at Cape Verde outside the coast of West Africa. Sampling commenced in May, 2012 and 43 samples were collected until June 2013 (24 h sampling). The samples were analyzed for selected polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), hexachlorbenzene (HCB) and chlordanes. The source regions of the air masses were evaluated for each sample using the FLEXPART model. FLEXPART is an atmospheric Lagrangian transport model, developed by Andreas Stohl and co-workers, which calculates the trajectories of so-called tracer particles (flexpart.eu). It was run in backward mode, in order to identify the source regions of air pollutants at a particular site. A general finding is that the concentrations measured are in the lower range in comparison to data from the literature, which is mainly attributed to the remoteness of the station from major sources and source regions. Factors controlling measured concentrations will be evaluated and discussed.
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