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In order to assess the potential influence of the costal environment on marine aerosol chemical composition, two parallel aerosol data sets, collected during two campaigns (coastal site campaign at Mace Head station and open ocean campaign in North Atlantic Ocean), are compared. Aerosol samples were analyzed for Water Soluble Organic Carbon (WSOC), Total Carbon (TC), and main inorganic ions. In addition, a detailed chemical characterization of WSOC was performed. Results show a strong similarity between size-segregated chemical composition in the submicron size interval, at the coastal station and open ocean site, thus excluding potential effects of the shore line environment. Only the coarse fraction seems in some way influenced by the proximity of the shoreline, the sea salt concentration being higher in this size interval for the coastal site. Keywords Aerosol chemistry, biogenic particles, coastal particles, marine aerosols [ABSTRACT FROM AUTHOR]

This study has been designed to investigate the factors that influence the occurrence of new particle formation events (particles >3 nm) in two anthropogenically influenced boundary layer regimes in Central Europe (Melpitz, Eastern Germany) and Southern Europe (San Pietro Capofiume "SPC" in the Po Valley, Italy). In particular, we study the similarities and differences of factors driving nucleation events at these two locations. The analysis encompasses three years of data at each observation site, between July 2003 and June 2006. Particle size distribution measurements were carried out using twin DMPS systems (Differential Mobility Particle Sizers) at each site, with particle size ranges of 3-800 nm, and 3-600 nm at Melpitz and SPC, respectively. In addition to particle size measurements, several gas and meteorological parameters are being measured for stations, including SO2, NO, NO2, NOx, O3, temperature, relative humidity, wind direction, wind speed, global radiation, precipitation, and atmospheric pressure. We utilized these parameters in our analysis of particle formation and growth processes. Our preliminarily results show that for Melpitz station, it is possible to separate between nucleation days and nonnucleation days by using just two variables (a product of radiation and sulphuric dioxide - its increase indicates increase of sulphuric acid concentration - and condensation sink"CS"). This result for Melpitz indicates that low enough CS value is needed together with high enough sulphuric acid production to drive nucleation and vice verse for nonnucleation days. For SPC station the same criterion could not separate nucleation days and nonnucleation days as efficiently as for Melpitz, and an overlap region between nucleation and nonnucleation days remained. Interestingly, however, the nonnucleation days in Po Valley are bound by the same criterion as in Melpitz, and it is the nucleation days that cause the Po Valley overlap. Keywords Nucleation days, nonnucleation days, driving nucleation factors [ABSTRACT FROM AUTHOR]

In the framework of the QUEST-EC project, an intensive measurement campaign was carried out in early spring 2004 at San Pietro Capofiume, a rural site located in the Po Valley. The aim was to investigate the mechanisms of new particle formation in a polluted environment, and to assess the role of aerosol chemical composition in the formation and growth of aerosol particles. The results confirm that new particle formation was preferentially associated with relatively clean air masses, and evidence that new particle formation in this polluted environment is due to a synergy between particular meteorological conditions and the physicochemical characteristics of aerosol particles. Keywords New particle formation, nucleation, aerosol chemistry [ABSTRACT FROM AUTHOR]