Measurements of Gaseous Carbonyls Using an Automated HPLC system during the BAQS-MET Field Study.

Measurements of gaseous carbonyls were made using an automated HPLC system, which utilizes the DNPH derivitization method, during the Border Air Quality and Meteorology Study (BAQS-MET). The BAQS-MET field campaign was conducted to investigate the effects of transport and lake breezes on pollutant levels in southwestern Ontario, as well as to determine the sources of these pollutants. The measurements took place in Ridgetown, ON from Jun 21st to July 10, 2007. Ridgetown is a rural area in close proximity to the United States, as well as Lake Erie and Lake St. Clair, rendering it an ideal location for the objectives of this field campaign. The levels of nine carbonyls (C1-C7) including methylglyoxal and o-tolualdehyde were measured on a 2-hour cycle time throughout the study. The median levels of the most abundant carbonyls were: 1.8 ppb for acetone, 1.7 ppb for formaldehyde and 0.92 ppb for acetaldehyde. These levels were significantly elevated during enhanced smog events that occurred during periods with south to southwesterly flow. The carbonyl data set is also being analyzed in conjunction with NMHC data collected at the same site via Suma canisters and GC-FID analysis, to determine the sources of carbonyls measured at the site and the photochemical age of the air masses.