Open AccessUrban and rural aerosol characterization of summer smog events during the PIPAPO field campaign in Milan, Italy
Author(s) -
Baltensperger U.,
Streit N.,
Weingartner E.,
Nyeki S.,
Prévôt A. S. H.,
Van Dingenen R.,
Virkkula A.,
Putaud J.P.,
Even A.,
ten Brink H.,
Blatter A.,
Neftel A.,
Gäggeler H. W.
Publication year - 2002
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2001jd001292
Subject(s) - aerosol , relative humidity , environmental science , particulates , soot , sulfate , atmospheric sciences , carbon black , total organic carbon , environmental chemistry , meteorology , chemistry , geography , combustion , physics , natural rubber , organic chemistry
A comprehensive range of aerosol parameters was measured at an urban and a rural site in the Milan, Italy metropolitan region during summer smog events in summer 1998. Measurements were performed as part of the Pianura Padana Produzione di Ozono (PIPAPO) field campaign to determine the sensitivity of O 3 production to NO X and volatile organic carbon concentrations at several ground stations. Primary aerosol parameters (i.e., direct emissions) such as aerosol black carbon showed a distinct diurnal variation with maxima at about 0000 and 0800 central European summer time (CEST), in contrast to secondary aerosol parameters such as sulfate and nitrate. Aerosol number size distributions were measured under ambient conditions as well as after conditioning with volatility and hygroscopicity systems. A mode at d = 20–30 nm in the number concentration was found at 0800 CEST and exhibited high volatility at 110°C (∼80% volume lost upon heating) but no hygroscopic behavior. Based on these measurements, small particles ( d < 40 nm) are thought to consist mainly of hydrophobic particulate organic matter, rather than soot or H 2 SO 4 aerosols. Two distinct hygroscopic modes with average growth factors d / d 0 ∼ 1.02 and 1.21–1.28 were found for particles with dry (relative humidity of <30%) diameters d 0 = 50–200 nm. Submicrometer aerosols exhibited lower volatility at the rural than at the urban site, which is attributed to additional particulate mass produced by secondary particle formation.