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

2002; American Geophysical Union; Volume: 107; Issue: D24 Linguagem: Inglês

10.1029/2001jd000827

2156-2202

F.M. McGovern, Maria João Nunes, Frank Raes, H. Gonzales‐Jorge,

Atmospheric Ozone and Climate

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.