Phenomenology and geographical gradients of atmospheric deposition in southwestern Europe: Results from a multi-site monitoring network

Abstract This article presents the results of a 3.5-year monitoring of atmospheric deposition from a 15-sites network covering remote, agricultural, urban and industrial areas in the Iberian Peninsula and the Balearic Islands. The atmospheric deposition of insoluble and soluble-inorganic aerosols has been studied from a comprehensive perspective. Annual fluxes of global, insoluble and soluble-inorganic aerosols are discussed. They vary significantly from one region to another, and depending of their nature they are enhanced in coastal regions or in continental areas. A number of sites display enhanced deposition fluxes as a result of the contribution from nearby sources: agricultural dust, industrial emissions, urban dust, or resuspension from a dissicated lake bed. In others, elevated aerosol fluxes are explained because of the magnification of atmospheric washout processes in mountain areas: African dust in the Central Pyrenees, or anthropogenic and marine aerosols in the Cantabrian Range. The impact of different sources affecting insoluble aerosol deposition, including African dust, regional resuspension and urban dust has been estimated. African dust deposition is enhanced in the Central Pyrenees and in the southernmost site of the network; regional resuspension affects significantly the Ebro Valley region; and urban contributions are rather similar in all cities, but slightly augmented in Zaragoza. The mean composition of soluble-inorganic fluxes is discussed and compared to other studies. Marine aerosols prevail in coastal areas and near the saline Gallocanta Lake as a result of local contributions; nitrogen species are enhanced in the Cantabrian region (washout of anthropogenic emissions) and in Gallocanta (impact of fertilizers); mineral dust in enhanced in the Ebro Valley (impact of regional dust resuspension) and again in the Cantabrian region (probably connected to industrial emissions and power generation). Three hotspots of phosphate deposition at regional background environments have been identified, advising the noteworthy impact of diverse anthropogenic sources at these areas.