Document: DIA-3-59-69

Atmospheric deposition in the Phoenix metropolitan area and its role in urban nutrient cycling.

HOPE, D.* ¹, J.R.ANDERSON ¹, N.B.GRIMM ¹ and S.BOONE ²

Arizona State University, Tempe, AZ 85287, USA ¹
Texas A&M, Corpus Christi, TX, USA ²
Texas A & M, Corpus Christi, TX, USA ³

Abstract:
Man is increasingly affecting biogeochemical cycling. This is particularly so in cities where nutrient and material fluxes, as well as the relative importance of transport and storage mechanisms, may be significantly modified with respect to less human-impacted ecosystems. Recent research on the Central Arizona-Phoenix Long Term Ecological Research (CAP LTER) program suggests that for nutrients such as nitrogen, atmospheric deposition (wet and dry) potentially represents one of the largest inputs to the ecosystem and that this is largely derived from NOx emissions in vehicle exhausts. However atmospheric transport and deposition of nutrients and other ions, along with the effect of that deposition on biogeochemical cycling and ecosystem function in cities and surrounding ecosystems is currently only poorly understood. Few empirical measures of nutrient deposition rates in cities have been made in the US, since most existing national monitoring networks e.g. National Atmospheric Deposition Program and NOAA's National Dry Deposition Network consist of sites which are located almost exclusively in pristine natural areas, remote from urban influences. The aim of the atmospheric deposition research at CAP LTER is to measure the spatial variation and overall rates of atmospheric deposition for the major nutrients and ions across the city and to understand how atmospheric deposition affects the functioning of other urban ecosystem processes, such as primary productivity. Data on the wet and dry deposition rates of major nutrients and ions are presented from a network of 9 collectors across the CAP study area. Spatial variations in deposition rates for nitrogen species and dissolved organic carbon will be discussed in terms of patterns in aerosol chemistry, land use and urban traffic patterns. The major ion chemistry of aerosols across the valley were obtained using Particle Induced X-ray Emission analysis. Multivariate analysis of these data reveal the likely sources of the aerosols contributing to dry deposition across the city.

Keywords: urban atmospheric deposition nutrients

This abstract is being presented at: 3:30 PM in session:
Poster Session #15: Nutrient Cycling.