FINE PARTICULATE ORGANIC MATERIAL AT MEADVIEW DURING THE PROJECT MOHAVE SUMMER INTENSIVE STUDY

The Brigham Young University (BYU) organic sampling system (BOSS) and the high flow rate multi-system BYU organic sampling system (BIG BOSS) , which use multi-channel diffusion denuder sampling techniques, were both used to collect samples of atmospheric fine particulate organic m aterial. Both systems were used at the Meadview sampling site located at the western boundary of the Grand Canyon National Park in northwest ern Arizona for the Project MOHAVE summer intensive sampling program i n August 1992. The concentrations of total fine particulate carbonaceo us material determined by temperature programmed volatilization for BO SS collocated replicate samples were in agreement with an uncertainty of +/-14%. A comparable agreement was seen between the BOSS and BIG BO SS samples. Carbonaceous material collected by the second of two seque ntial quartz filters was shown to have originated from organic materia l lost from particles during sampling. About one-half of the fine part iculate organic material was lost from particles during sample collect ion. These semi-volatile organic compounds lost from particles during sampling were characterized by GC/MS analysis. The concentrations of n -alkanes, n-fatty acids, n-fatty methyl esters, and phthalic acid as a function of fine particulate size were obtained for compounds both re tained by and lost from particles during sampling. The possible source s of fine particulate semi-volatile organic material collected at Mead view, and the particle size distribution of fine particulate organic m aterial, n-alkanes, n-fatty acids, and n-fatty esters are discussed.