Marine and anthropogenic aerosols at Punta Del Hidalgo, Tenerife, and the aerosol nitrate number paradox

Abstract

[1] Results from analysis of aerosol ion composition and condensation nuclei (CN) concentration measurements carried out at the second Aerosol Characterization Experiment (ACE-2) Tenerife site, in the eastern North Atlantic subtropical region between July 1995 and May 1997, are described. Sea-salt derived Na + dominated the samples having an average concentration of 2.4 μg m -3. Extensive anthropogenic influences are evident with average non-sea-salt sulfate (nssSO 4 2-) and nitrate (NO 3 -) concentration values of 2.1 μg m -3 and 1.3 μg m -3 respectively. High levels of these species are linked to air mass transport from Europe: observed as short-term (2-3 days) pollution peaks. The pollution peaks overlie a summertime maximum in background levels. From comparison with Southern Hemisphere data, it is estimated that ∼80% of the observed nssSO 4 2- originated from anthropogenic sources. Regression analysis shows a high degree of linearity between the NO 3 - and CN concentration, which is stronger than found with between NssSO 4 2 and CN concentration. This is considered paradoxical as in the maritime atmosphere NO 3 - has primarily been found in supermicron size range linked to sea-salt, while nssSO 4 2- and CN are primarily considered to be submicron aerosol. The CN:NO 3 - linearity is considered to arise from NO 3 - formation and transport processes over ocean regions. Copyright 2002 by the American Geophysical Union.