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A global assessment of precipitation chemistry and deposition of sulfur, nitrogen, sea salt, base cations, organic acids, acidity and pH, and phosphorus

Vet, R and Artz, RS and Carou, S and Shaw, M and Ro, CU and Aas, W and Baker, A and Bowersox, VC and Dentener, F and Galy-Lacaux, C and Hou, A and Pienaar, JJ and Gillett, R and Forti, MC and Gromov, S and Hara, H and Khodzher, T and Mahowald, NM and Nickovic, S and Rao, PSP and Reid, NW (2014) A global assessment of precipitation chemistry and deposition of sulfur, nitrogen, sea salt, base cations, organic acids, acidity and pH, and phosphorus. Atmospheric Environment, 93. pp. 3-100.

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A global assessment of precipitation chemistry and deposition has been carried out under the direction of the World Meteorological Organization (WMO) Global Atmosphere Watch (GAW) Scientific Advisory Group for Precipitation Chemistry (SAG-PC). The assessment addressed three questions: (1) what do measurements and model estimates of precipitation chemistry and wet, dry and total deposition of sulfur, nitrogen, sea salt, base cations, organic acids, acidity, and phosphorus show globally and regionally? (2) has the wet deposition of major ions changed since 2000 (and, where information and data are available, since 1990) and (3) what are the major gaps and uncertainties in our knowledge? To that end, regionally-representative measurements for two 3-year-averaging periods, 2000-2002 and 2005-2007, were compiled worldwide. Data from the 2000-2002 averaging period were combined with 2001 ensemble-mean modeling results from 21 global chemical transport models produced in Phase 1 of the Coordinated Model Studies Activities of the Task Force on Hemispheric Transport of Air Pollution (TF HTAP). The measurement data and modeling results were used to generate global and regional maps of major ion concentrations in precipitation and deposition. A major product of the assessment is a database of quality assured ion concentration and wet deposition data gathered from regional and national monitoring networks. The database is available for download from the World Data Centre for Precipitation Chemistry ( The assessment concludes that global concentrations and deposition of sulfur and nitrogen are reasonably well characterized with levels generally highest near emission sources and more than an order of magnitude lower in areas largely free of anthropogenic influences. In many parts of the world, wet deposition of reduced nitrogen exceeds that of oxidized nitrogen and is increasing. Sulfur and nitrogen concentrations and deposition in North America and Europe have declined significantly in line with emission reduction policies. Major regions of the world, including South America, the more remote areas of North America, much of Asia, Africa, Oceania, polar regions, and all of the oceans, are inadequately sampled for all of the major ions in wet and dry deposition, and particularly so for phosphorus, organic forms of nitrogen, and weak acids including carbonates and organic acids. Measurement-based inferential estimates of dry deposition are limited to sulfur and some nitrogen in only a few regions of the world and methods are highly uncertain. The assessment concludes with recommendations to address major gaps and uncertainties in global ion concentration and deposition measurements.

Item Type: Article
Additional Information: Copyright of this article belongs to Elsevier
Uncontrolled Keywords: Air pollution; Atmospheric chemistry; Atmospheric movements; Concentration (process); Emission control; Nitrogen; Organic acids; Particulate emissions; pH; Phosphorus; Positive ions; Precipitation (chemical); Sulfur; Uncertainty analysis; Watches, Assessment; Chemical transport models; Emission reduction policies; Global atmosphere watches; Major ions; Measurements and modeling; Precipitation chemistry; World meteorological organizations, Deposition, acetic acid; base; base cation; carbonic acid derivative; carboxylic acid; cation; formic acid; nitrogen; phosphorus; sea salt; sodium chloride; sulfur; unclassified drug, acidity; atmospheric deposition; atmospheric pollution; cation; concentration (composition); database; global climate; nitrogen; organic acid; pH; precipitation quality; sea salt; sulfur, acid deposition; acidity; aerosol; Africa; air pollution control; Antarctica; article; Asia; atmospheric deposition; atmospheric transport; biomass; Central Africa; chemical composition; coastal waters; combustion; desulfurization; dry deposition; dust; electric power plant; Europe; forest; geographic distribution; nitrogen concentration; nitrogen deposition; North America; Pacific islands; particle size; precipitation; priority journal; rural area; savanna; sea; seashore; seasonal variation; South America; vegetation; watershed; wet deposition; wind, Africa; Asia; Europe; North America; oceanic regions; South America
Subjects: Meteorology and Climatology
Depositing User: IITM Library
Date Deposited: 23 May 2015 09:14
Last Modified: 23 May 2015 09:14

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