Low concentrations of persistent organic pollutants (POPs) in air at Cape Verde

Therese Haugdahl Nøst; Anne Karine Halse; Martin Schlabach; Are Bäcklund; Sabine Eckhardt; Knut Breivik

doi:10.1016/j.scitotenv.2017.08.217

Low concentrations of persistent organic pollutants (POPs) in air at Cape Verde

Sci Total Environ. 2018 Jan 15:612:129-137. doi: 10.1016/j.scitotenv.2017.08.217. Epub 2017 Sep 1.

Authors

Therese Haugdahl Nøst¹, Anne Karine Halse², Martin Schlabach², Are Bäcklund², Sabine Eckhardt², Knut Breivik³

Affiliations

¹ NILU - Norwegian Institute for Air Research, the FRAM Centre, P.O. Box 6606, Langnes, NO-9296 Tromsø, Norway; UiT - the Arctic University of Norway, P.O. Box 6050, Langnes, NO-9037 Tromsø, Norway. Electronic address: thn@nilu.no.
² NILU - Norwegian Institute for Air Research, P.O. Box 100, NO-2027 Kjeller, Norway.
³ NILU - Norwegian Institute for Air Research, P.O. Box 100, NO-2027 Kjeller, Norway; University of Oslo, Department of Chemistry, P.O. Box 1033, NO-0315 Oslo, Norway.

PMID: 28850833
DOI: 10.1016/j.scitotenv.2017.08.217

Abstract

Ambient air is a core medium for monitoring of persistent organic pollutants (POPs) under the Stockholm Convention and is used in studies of global transports of POPs and their atmospheric sources and source regions. Still, data based on active air sampling remain scarce in many regions. The primary objectives of this study were to (i) monitor concentrations of selected POPs in air outside West Africa, and (ii) to evaluate potential atmospheric processes and source regions affecting measured concentrations. For this purpose, an active high-volume air sampler was installed on the Cape Verde Atmospheric Observatory at Cape Verde outside the coast of West Africa. Sampling commenced in May 2012 and 43 samples (24h sampling) were collected until June 2013. The samples were analyzed for selected polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), hexachlorobenzene (HCB) and chlordanes. The concentrations of these POPs at Cape Verde were generally low and comparable to remote sites in the Arctic for several compounds. Seasonal trends varied between compounds and concentrations exhibited strong temperature dependence for chlordanes. Our results indicate net volatilization from the Atlantic Ocean north of Cape Verde as sources of these POPs. Air mass back trajectories demonstrated that air masses measured at Cape Verde were generally transported from the Atlantic Ocean or the North African continent. Overall, the low concentrations in air at Cape Verde were likely explained by absence of major emissions in areas from which the air masses originated combined with depletion during long-range atmospheric transport due to enhanced degradation under tropical conditions (high temperatures and concentrations of hydroxyl radicals).

Keywords: Active air sampling; Monitoring; Particle dispersion modelling; Persistent organic pollutants; Tropical regions.