Identifying urban sources as cause of elevated grass pollen concentrations using GIS and remote sensing

[摘要] We examine here the hypothesis that during flowering, the grass pollenconcentrations at a specific site reflect the distribution of grass pollensources within a few kilometres of this site. We perform this analysis ondata from a measurement campaign in the city of Aarhus (Denmark) using threepollen traps and by comparing these observations with a novel inventory ofgrass pollen sources. The source inventory is based on a new methodologydeveloped for urban-scale grass pollen sources. The new methodology isbelieved to be generally applicable for the European area, as it relies oncommonly available remote sensing data combined with management informationfor local grass areas. The inventory has identified a number of grass pollensource areas present within the city domain. The comparison of the measuredpollen concentrations with the inventory shows that the atmosphericconcentrations of grass pollen in the urban zone reflect the source areasidentified in the inventory, and that the pollen sources that are found toaffect the pollen levels are located near or within the city domain. Theresults also show that during days with peak levels of pollen concentrationsthere is no correlation between the three urban traps and an operational traplocated just 60 km away. This finding suggests that during intenseflowering, the grass pollen concentration mirrors the local sourcedistribution and is thus a local-scale phenomenon. Model simulations aimed atassessing population exposure to pollen levels are therefore recommended totake into account both local sources and local atmospheric transport, and notto rely only on describing regional to long-range transport of pollen. Thederived pollen source inventory can be entered into local-scale atmospherictransport models in combination with other components that simulate pollenrelease in order to calculate urban-scale variations in the grass pollenload. The gridded inventory with a resolution of 14 m is therefore madeavailable as supplementary material to this paper, and the verifying grasspollen observations are additionally available in tabular form.

[学科分类] 地球化学与岩石