Final Report STUDIES OF THE CHEMISTRY OF UNPOLLUTED ATMOSPHERES Prepared for: ATMOSPHERIC PHYSICS AND CHEMISTRY LABORATOkY

Measurements of aerosol concentration and size distribution were made with a light scattering type particle counter and condensation nuclei counters at sea level and 2200 meter altitudes using sites at Cape Blanco, and Crater Lake, Oregon. Goetz aerosol spectrometer was used to determine size distributions for the chloride and sulfate frac-tions of the total aerosol..) The data collected in marine air masses support earlier findings of sea-spray aerosol size distributions ajd lack of chemical fractionation during bubble burst aerosol formation. The data indicate that significant amounts of sea spray aerosol do not penetrate to low and mid-tropospheric altitudes above 2000 meters. The aerosols typical of this elevation were found to have size distributions (for radii greater than about 0.1 im) well approximated by a power law with an exponent of 3 to 4. They were found to have sulfur to chloride ratios of about 8 and considerable concentrations of substances other than sulfur and chloride. High altitude tropospheric air mass aerosols, observed on this program at Crater Lake during periods of subsidence, have lower concentrations than found for lower altitude tropospheric aerosols and their power law representations are characterized by lower exponential values. Aersols which were identified with tropospheric levels above 2000 m are believed to be aged aerosols from continental sources rather than sea-surface aerosols transported to higher altitudes. THIS DOCUMENT CONTAINE