A Global Overview of Atmospheric Acid Deposition Fluxes |
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Authors: | D M Whelpdale P W Summers E Sanhueza |
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Institution: | (1) Atmospheric Environment Service, 4905 Dufferin Street, Downsview, Ontario, M3H 5T4, Canada;(2) 805-30 Harding Blvd. West, Richmond Hill, Ontario, L4C 9M3, Canada;(3) Instituto Venezolano de Investigaciones Cientificas, Apartado 21827, Caracas, 1020A, Venezuela |
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Abstract: | This paper presents a summary of globalacid deposition flux data taken from a globalassessment report on acid deposition prepared forUNEP/WMO (Whelpdale and Kaiser, 1996). There is a largevariation in the spacial coverage and reliability ofmonitoring around the world. Many more stationsmeasure wet deposition than collect appropriate datafor estimating dry deposition. The widespread regionswith highest precipitation concentrations anddeposition fluxes of sulphate and nitrate coincideclosely with the regions of highest density ofSO2 and NOx precursor emissions occurringprimarily in the mid-latitude, northern hemispherebelt where a large fraction of the worlds fossilfuels is consumed. Organic acids in precipitation makea minor contribution to acidity (<20%) inindustrial regions, but in the rest of the world theyare of same order, or even exceed, inorganic acids.Less is known about dry deposition, but it appears topredominate near strong emission sources with wetdeposition predominating farther downwind. The molarratio of the N/S contribution to acidic deposition isclose to 1.0 over large areas of Europe and NorthAmerica, but is highly variable elsewhere, beinghighest in equatorial regions due to biomass burningand lowest near smelters and other large sources of SO2. |
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Keywords: | global wet deposition dry deposition sulphate nitrate ammonium calcium organic acids reigonal budgets |
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