Longterm Atmospheric Deposition Monitoring

The aims of our study are to examine the magnitude and spatial variability in theconcentration and flux of wet deposited NO3-N, NH4-N, DOC, PO4-P, Cl, SO4, H+, Ca,Mg, Na, K across the Central Arizona-Phoenix region, including the developed urbancore and outlying desert. Also to examine patterns of coarse dry particulatedeposition across the study area and provide some minimum estimates on levels of drydeposition of these ions. We were particularly interested to answer the question:‘To what extent are concentrations and fluxes of these ions enhanced at sites withinthe urban core relative to undeveloped desert sites upwind and downwind of thecity’. Currently we operate eight wet-dry collectors located to form a transect runningapproximately W-E across the study area from outlying desert to the west, upwind ofthe prevailing synoptic wind direction, through agriculture to urban core sites, totwo downwind sites in the desert to the east and northeast (map of bucketlocations). Collectors are co-located at sites of Maricopa County or ArizonaDepartment of Environmental Quality monitoring stations wherever possible.