Short-Term Variability of Fine Inorganic Particulate Matter Over Athens, Greece

Abstract

On-line, measurements of inorganic ions were performed at Thissio station (December 2014–October 2015), in order to comprehend the sources and the factors that affect variability of fine inorganic aerosol in Athens, Greece. Atmospheric air is sampled through a 1 μm cut-size impactor, to a particle-into-liquid sampler, coupled with ion chromatography. Simultaneously, fine aerosol (PM2.5) is collected daily on quartz filters, and further analysed by ion chromatography. The concentrations of Cl−, NO−3NO3−{\text{NO}}_{3}^{ - } and SO2−4SO42−{\text{SO}}_{4}^{2 - } measured by PILS average 0.29 ± 0.20, 0.69 ± 0.35 and 1.86 ± 1.6 μg m−3, respectively, and are in accordance with the corresponding concentrations obtained by filter analysis. The seasonal variability of nss-SO2−4SO42−{\text{SO}}_{4}^{2 - } presents maxima during summer, while minimum appears in winter, due to the enhanced summer photochemistry combined with limited precipitation and intensive regional transport. During both seasons, sulfate presents no distinct diurnal variability according to its regional character. On the contrary, nitrate presents an opposite seasonality with winter maxima and summer minima, since high temperatures tend to dissociate fine mode ammonium nitrate into nitric acid and ammonia. Additionally, a clear diurnal variation is observed for both seasons with maximum values during nighttime due again to lower temperatures occurred during nighttime compared to daytime.