Monitoring of ambient air quality and meteorology during the Beltsville site clean air status and trends network (CASTNET) instrument ccomparison project

The atmosphere is a complex mixture of natural and anthropogenic compounds with diverse properties, producing adverse affects on human health, ecology, ozone depletion, visibility, and climate. Aerosols play an important role in the atmosphere and are the cause for increased concern regarding their possible impact on climate, air quality, and human health. In order to address these issues, increased specificity and precision of reliable and highly resolved measurements of aerosols and atmospheric gases are required. This presentation describes the air quality and meteorology monitoring undertaken, as part of the Beltsville Instrument Comparison Project, by the Environmental Protection Agency (EPA), with the aim to understand the relevance and significance of the mechanisms and compounds contributing to particle formation and cycling. Measurements of the mixing ratios of ammonia, nitric acid, nitrous acid, hydrochloric acid, sulfur dioxide and the corresponding water-soluble inorganic aerosol species, ammonium, nitrate, nitrite, chloride and sulfate and their diel (24-hr) and diurnal (day and night) variation at a rural site will be analyzed in order to investigate chemical mechanisms describing the formation of condensable species and investigate the linkage between airborne particles with surrounding ambient gases.