Fine Particle Water and PH in an Urban and Remote Location and the Role of Biomass Burning

Abstract

Particle water (LWC) and pH are calculated for the fine fraction of aerosols sampled at two locations in Greece; an urban (Athens) and a remote background (Finokalia). Using concurrent measurements of aerosol chemical composition, tandem light scattering coefficients and the thermodynamic model ISORROPIA-II, LWC mass concentrations associated with the aerosol inorganic and organic components are determined for both locations. The predicted pHs are interpreted based on different sources that influence air quality in these locations. For Finokalia closure between predicted aerosol water and that determined by comparison of ambient with dry light scattering coefficients was achieved within 8 % (slope = 0.92, R-2 = 0.8). For both locations a significant diurnal variability is found for both organic and inorganic water constituents. The average value for total aerosol water was 2.19 +/- 1.75 mu g m(-3) and 13.86 +/- 17.26 mu g m(-3) for Finokalia and Athens, respectively. The large difference in LWC is associated with intense biomass burning activities during wintertime in Athens. The aerosol at Finokalia was found to be highly acidic with pH varying from 0.5 to 2.8 throughout a 5-month study period. Biomass burning exhibited the highest pH (2.77 +/- 0.88) with values being comparable to the ones derived from Athens from days with high biomass burning influence (2.83 +/- 0.47).