LONG-TERM AEROSOL AND TRACE ACIDIC GAS COLLECTION AT MAUNA-LOA-OBSERVATORY 1979-1991

Weekly aerosol samples have been collected and analyzed consistently a t Mauna Loa Observatory from February 1979 through June of 1991. Previ ous studies reported data through April of 1985. This paper focuses ma inly on the data from May 1985 to June 1991. However, previous data ha ve been included when appropriate to examine the entire data record. E lemental concentrations, enrichment factors, principal component analy sis and chemical mass balancing have been used to examine this 12 year data record. Yearly Asian dust episodes are the major contributor to trace metal concentrations and variance. Marine material contributes o nly st third of the trace metal mass compared to the crustal contribut ion. Anthropogenic and biogenic material usually contribute less than 5% of the trace element mass (excluding carbon and sulfate). Sulfate, which was measured by ion chromatography for part of the period, contr ibutes a mass similar to crustal mineral; however, it does not have a strong seasonal pattern. A pollution episode in 1989 increased the bud get of several elements by an order of magnitude or more. The trace ac idic gas data support the conclusion that marine material in the free troposphere has been weathered leading to chlorine depletion in marine particles.