Characterization of aerosol absorption properties and PM1 at a mountain site located in the southeast of the Iberian Peninsula

Abstract

PM1 concentrations and aerosol absorption properties were measured during 2018 at a mountain site (1558 m a.s.l.) located in the southeast of the Iberian Peninsula, close to the Mediterranean coast. Average values of PM1 and the absorption coefficient (σap-520 nm) (4.1 μg⋅m−3 and 1.74 Mm−1, respectively) were within the ranges reported for other high-altitude stations. The value of the Absorption Angstrom Exponent (AAE) (1.20) suggests that, in general, black carbon (BC) from fossil fuel or vehicle exhaust was the major absorbing component. σap and PM1 showed peaks in the summer season, which is characteristic of this type of environment, whereas AAE had an opposite seasonal pattern. This was possibly due to the greater contribution of biomass burning (BB) during the colder months. The variation of PM1, σap and AAE as a function of air mass origins was also assessed. PM1 concentrations showed increases of more than 50% for north African and regional origins. Similarly, the highest values of σap were associated with these trajectories. In contrast, AAE values were highest (1.28-median value) when air mass trajectories originated from the Atlantic. This may be due to the seasonal frequency of occurrence of these trajectories rather than the composition of the transported aerosol.