Backward air trajectory models for detecting pollen airborne sources of Castanea in Ronda (South Spain)

Abstract

Ronda is located in a rural area close to the natural Parks Sierra de Grazalema and Sierra de las Nieves, surrounded by crops, natural and seminatural vegetation. The Genal Valley, which is located at the southwest of Ronda, is the biggest Castanea sativa Mill. crop area in Andalusia (South Spain) but there are also others C. sativa crops in different areas close to Ronda. This increases the Castanea atmospheric pollen levels in Ronda, the highest of Malaga province. Castanea pollen has been cited by different authors as potentially allergenic. The objective of this preliminary study was to determine the main sources of Castanea pollen detected in Ronda during the period in which the highest concentrations were detected along the year 2017. The pollen samplings were made by means of a Hirst-type volumetric pollen trap. The samples obtained were mounted and counted according to the methodology proposed by the Spanish Aerobiology Network (REA). Backward air trajectories were calculated according to HYSPLIT 4 model. Models were run five times a day by using R software for the whole month of June 2017. Due to the wind dynamics in Ronda, the main source of Castanea airborne pollen was not the expected (the Genal Valley). The dominant winds in June 2017 came from the southeast of Ronda and brought Castanea pollen from the crops of two nearby localities, Istan and Ojen, which are widely smaller than those situated in the Genal Valley. Therefore, due to the high pollen production of these crops, predictive models for the Castanea airborne pollen in Ronda should be done in future researches in order to prevent allergic diseases in the population. Additionally, by studing air trajectory models, the cross pollination between Castanea populations in the area can be estimated.