HYSPLIT as an environmental impact assessment tool to study the data discrepancies between Olea europaea airborne pollen records and its phenology in SW Spain

Abstract

The olive tree (Olea europaea) is a native evergreen tree in the Mediterranean region, being one of the most important causes of seasonal respiratory allergies in Mediterranean countries. This work aims to relate flowering phenology, source tree distribution, meteorology, and airborne pollen records for this species and to analyse the possible arrival of air masses from distant areas during days when differences between the phenological and pollen peaks. Aerobiological sampling was carried out in Badajoz (SW Spain) for 4 years (2016–2019) using a Hirst volumetric sampler. Trees were geolocalized in the city and surrounding areas. The pollination phenology of 15 specimens was studied for four years (2016–2019) during the months from April to June. The daily data for the whole period and the hourly data for the four years, including pollen records and meteorology, were analysed. The comparison between the pollen records and sources distribution was assessed. The main pollen season (thereafter, MPS) lasted an average of 34.5 (29–40) days. Phenological observations indicate that pollination occurred for 26.5 days and was mostly within the period of recorded airborne pollen; however, were days with airborne pollen recorded outside the pollination period. In 2017 the peak day was recorded when the flowering period has reached only the 10%, in other seasons this value reached the maximum peak of pollen concentration was found only a few days after the maximum of flowering. The hourly analysis showed that the maximum pollen concentrations were reached just after noon. The analysis of pollen sources and pollen records showed a close relationship with the predominant winds and tree distributions. The observed discrepancies between phenological and aerobiological data (in 2017 and 2018) were explained by the movement of air masses and long-distance transport.