Methoxyphenols and levoglucosan ratios in PM2.5 from wheat and Kentucky bluegrass stubble burning in eastern Washington and northern Idaho.

Eastern Washington is compromised by various pollution sources, of which agricultural burning is a particular burden. Smoke from field burning is a nuisance to nearby communities and is a concern for health. This study evaluates levoglucosan (LG) and methoxyphenols (MPs) as potential tracers for apportioning field burning smoke. PM2.5 (particulate matter < 2.5 microM m in aerodynamic diameter) samples from wheat and Kentucky bluegrass (KBG) stubble smoke were collected from chamber and field burns. The samples were analyzed for inorganic and organic tracers, including LG and 19 MPs. For the chamber experiments, the amount of LG, approximately 23 microg mg(-1) PM2.5, found in wheat and KBG stubble smoke was similar, while the total MPs was higher in wheat. Trace elements associated with soil were found in smoke samples in the field. Syringaldehyde, acetosyringone, and coniferylaldehyde were found to be the most prominent particle-phase MPs in wheat smoke, and these compounds were not always present in detectable amounts in KBG smoke. The ratio of LG/ syringaldehyde found in wheat (78 +/- 27) was higher than the same ratio reported for softwoods (22 +/- 3) and hardwoods (approximately 5). Similarly, the ratio of LG/coniferylaidehyde was higher in wheat stubble smoke (180 +/- 39) compared to that in softwoods (approximately 7) and hardwoods (approximately 8).