Evaluation of particulate trace species in southwest desert atmosphere

Abstract

A sampling program using high-volume filter samples for studying the concentration and composition of particulate matter in the arid southwest (in and near Tucson, Ariz.) was established in January 1974. Through the use of statistical techniques and examination of enrichment factors, it is possible to make a number of suggestions regarding the sources for and the cycle of various species in the desert rural and urban atmosphere. Large particle airborne soil or crustal materials dominate the aerosol population found in both the urban and rural atmosphere with over a dozen of the measured species directly attributable to this source. Nonsoil species, in general, appear to be fairly well mixed and probably result primarily from nonurban anthropogenic and natural sources. The acid-base nature of airborne gases and particles would appear to control the gas and particle distribution of ammonia and to largely define the particulate sulfate speciation (primarily (NH/sub 4/)/sub 2/SO/sub 4/). Large seasonal fluctuations, consistent with the climatology and meterology for the area under investigation, are seen in the concentration and composition of particulate matter in the desert atmosphere.