Master Thesis defence - Anna Grube – Niels Bohr Institute - University of Copenhagen

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Master Thesis defence - Anna Grube

Particulate air pollution and its characteristic sources in the high Arctic at Station Nord, N.E. Greenland.

The present project uncovers the characteristics of particulate Arctic air pollution and its sources at the high Arctic at Station Nord, N.E. Greenland with special attention to Black Carbon.

The purpose was approached by analysing Black Carbon (BC) concentrations measured with a Particle Soot Absorption Photometer (PSAP) in the time period from March 2008 to April 2011 at Station Nord. This measurements show a seasonal variations in accordance with the Arctic haze cycle (maximum in winter and early spring). An exceptional high BC event (110 ng m−3) was found to occur in the early spring of 2008 with subsequent years reaching a low winter concentration (about 60 ng m−3). This exceptional high BC event was found coincide with a strong PolarVortex (high indices of the Arctic Oscillation (AO) and the North Atlantic Oscillation (NAO) mode). An additional analysis of BC concentrations from Flade Isblink ice core covering the time period 1950 to 2000 verifies to some extent the trend of high BC events during high positive winter modes of AO and NAO.

Filter samples were analysed for Organic Carbon (OC) and Elemental Carbon (EC)by a carbon analyser (OC EC analyser) in the time period from July 2008 to February 2011. The mean concentrations are found for OC (0.11±0.08 μg m−3),EC (0.01±0.01 μg m−3) and Total Carbon (TC) (0.12±0.08 μg m−3). The relative contribution of EC to TC is found to 11 ±8 %. Furthermore, EC concentrations and the sulphate concentrations analysis by Ion Chrometography (IC) were studied and found to have similar seasonal patterns as BC concentrations. An analysis of the correlation between EC and the light absorption coefficient reported from PSAP resulted in a specific absorption coefficient σspecific = 7.82 m2 g−1, which isin agreement with literature.

The total chemical dataset retrieved by the Proton Induced X-ray Emission (PIXE) method together with BC and sulphate was analysed by the COnstrained Physical REceptor Model (COPREM) in order to investigate sources and source apportionment at Station Nord. The results of this analysis show that the anthropogenic sources, combustion and metal industry are the main contributors to BC concentrations. Further, metal industry contributes with the largest fraction to the source apportionment in early spring. The same pattern is found for sulphate with a small contribution from marine sources in late autumn and winter.

Supervisor: Peter Ditlevsen