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

Published in Atmospheric Environment, v. 93:3-100
Authors

Vet, R., Artz, R.S., Carou, S., Shaw, M., Ro, C., Aas, W., Baker, A., Bowersox, V.C., Dentener, F.J., Galy-Lacaux, C., Hou, A., Pienaar, J.J., Gillett, R., Forti, M.C., Gromov, S., Hara, H., Khodzher, T., Mahowald, N.M., Nickovic, S., Rao, P.S.P. and Reid, N.W.
Publication year 2014
DOI https://doi.org/10.1016/j.atmosenv.2013.10.060
Affiliations
  • Atmospheric Science and Technology Directorate, Environment Canada, Toronto, Ontario, Canada
  • Air Resources Laboratory, National Oceanic and Atmospheric Administration (NOAA), College Park, MD, USA
  • Norwegian Institute for Air Research (NILU), Kjeller, Norway
  • School of Environmental Sciences, University of East Anglia, Norwich, UK
  • QA/SAC Americas, World Meteorological Organization Global Atmosphere Watch, Champaign, IL, US
  • European Commission, Joint Research Centre, Institute for Environment and Sustainability, Ispra, Italy
  • Laboratoire d'Aérologie, Observatoire Midi Pyrénées, Toulouse, France
  • Faculty of Natural Sciences, North-West University, Potchefstroom, South Africa
  • CSIRO Marine and Atmospheric Research, Aspendale, Victoria, Australia
  • Instituto Nacional de Pesquisas Espaciais, Ministério da Ciência, Tecnologia e Inovação, São José dos Campos, São Paulo, Brazil
  • Institute of Global Climate and Ecology, Roshydromet and RAS, Moscow, Russian Federation
  • Department of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan
  • Limnological Institute, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russian Federation
  • Earth and Atmospheric Sciences, Cornell University, Ithaca, NY, USA
  • Atmospheric Research and Environment Branch (AREB), World Meteorological Organization, Geneva, Switzerland
  • Indian Institute of Tropical Meteorology, Pune, India
  • Retired from Ontario Ministry of the Environment, Toronto, Ontario, Canada

 
IAI Program

CRN3
IAI Project CRN3005
Keywords
Precipitation chemistry
Deposition
Emissions
Major ions
Global Atmosphere Watch
Assessment
pH

Highlights

•Assessed the global distribution of precipitation composition and deposition of major ions.

•Produced a global data set of quality assured wet deposition monitoring data for 2000–2002 and 2005–2007.

•Generated global wet deposition maps of major ions combining measurement and modeling results.

•Established that sulfur and nitrogen wet deposition is highest in parts of Asia, Europe and eastern North America.

•Determined that major gaps in wet and dry deposition monitoring exist globally.

Abstract

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&ndash2002 and 2005&ndash2007, were compiled worldwide. Data from the 2000&ndash2002 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 (http://wdcpc.org/). 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.