Chemical composition of boundary layer aerosol over the Atlantic Ocean and at an Antarctic siteReport as inadecuate

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1 FMI - Finnish Meteorological Institute 2 Department Department of Chemistry 3 KU - University of Copenhagen 4 Department of Atmospheric Sciences

Abstract : Aerosol chemical composition was measured over the Atlantic Ocean in November?December 1999 and at the Finnish Antarctic research station Aboa in January 2000. The concentrations of all anthropogenic aerosol compounds decreased clearly from north to south. An anthropogenic influence was still evident in the middle of the tropical South Atlantic, background values were reached south of Cape Town. Chemical mass apportionment was calculated for high volume filter samples Dp80% in the Southern Ocean, and 10% in most samples, also at Aboa. The correlation of biomass-burning-related aerosol components with 210Pb was very high compared with that between nss calcium and 210Pb which suggests that 210Pb is a better tracer for biomass burning than for Saharan dust. The ratio of the two clear tracers for biomass burning, nss potassium and oxalate, was different in European and in African samples, suggesting that this ratio could be used as an indicator of biomass burning type. The concentrations of continent-related particles decreased exponentially with the distance from Africa. The shortest half-value distance, ~100 km, was for nss calcium. The half-value distance of particles that are mainly in the submicron particles was ~700±200 km. The MSA to nss sulfate ratio, R, increased faster than MSA concentration with decreasing anthropogenic influence, indicating that the R increase could largely be explained by the decrease of anthropogenic sulfate.

Author: A. Virkkula - K. Teinilä - R. Hillamo - V.-M. Kerminen - S. Saarikoski - M. Aurela - J. Viidanoja - J. Paatero - I. K. Koponen -



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