HR: 14:40h
AN: B33G-05    [Abstracts]
TI: Linking the Nitrogen and Water Cycless
AU: * Holland, E A
EM: eholland@ucar.edu
AF: National Center for Atmospheric Research, The Institute for Integrative and Multidisciplinary Earth Studies and the Atmospheric Chemistry Division, Boulder, CO 80302
AU: Aulenbach, S
B33G-05 AF: NCAR, TIIMES & CGD, Boulder, CO 80305
AU: Sulzman, J
B33G-05 AF: National Center for Atmospheric Research, The Institute for Integrative and Multidisciplinary Earth Studies and the Atmospheric Chemistry Division, Boulder, CO 80302
AB: The global nitrogen cycle has been profoundly perturbed during the industrial era through fossil fuel combustion and agricultural intensification. There are few observations with adequate temporal and spatial coverage to understand the changing global nitrogen cycle. The atmospheric deposition networks designed to address the impact of acid rain deposition onto rural and remote areas in the some most industrialized regions of the world provide a key opportunity. We examined the 25 year record of precipitation removal of a atmospheric nitrogen, ammonium and nitrate, for the conterminous United States and Western Europe. The observations were collected by the National Atmospheric Deposition Program and National Trends Network (NADP/NTN) and European Monitoring for the Environment Programme (EMEP) measurement networks using a seasonal trend LOESS statistical approach . In Western Europe, during the time period of greatest sampling, there was a significant reduction in the number of observations that fell in the highest quartile of the observational record. In the US, there was no similar reduction in high quartile occurrences. On a continental scale for both the US and Western Europe, there was little overall trend in ammonium or nitrate wet deposition. The lack of a clear trend suggests that the emissions of ammonia and nitrogen oxides over the time period between 1978 and 2003 have been relatively constant, despite the implementation of a series of Transboundary Air Pollution Agreements and Clean Air Acts targeting the emissions of nitrogen oxides. The emissions conclusion assumes little or no change in the proportion of total atmospheric nitrogen removed by precipitation. Both ammonium and nitrate wet deposition showed significant seasonal cycles and inter-annual variability driven by precipitation.
DE: 0315 Biosphere/atmosphere interactions (0426, 1610)
DE: 0400 BIOGEOSCIENCES
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0426 Biosphere/atmosphere interactions (0315)
DE: 0469 Nitrogen cycling
SC: Biogeosciences [B]
MN: Fall Meeting 2005