EMISSIONS FROM SMOLDERING COMBUSTION OF BIOMASS MEASURED BY OPEN-PATHFOURIER-TRANSFORM INFRARED-SPECTROSCOPY

Biomass samples from a diverse range of ecosystems were burned in the Intermountain Fire Sciences Laboratory open combustion facility. Midin frared spectra of the nascent emissions were acquired at several heigh ts above the fires with a Fourier transform infrared spectrometer (FTI R) coupled to an open multipass cell. In this report, the results from smoldering combustion during 24 fires are presented including product ion of carbon dioxide carbon monoxide, methane, ethene, ethyne, propen e, formaldehyde, 2-hydroxyethanal, methanol, phenol, acetic acid, form ic acid, ammonia, hydrogen cyanide, and carbonyl sulfide. These were t he dominant products observed, and many have significant influence on atmospheric chemistry at the local, regional, and global scale. Includ ed in these results are the first optical, in situ measurements of smo ke composition from fires in grasses, hardwoods, and organic soils. Ab out one half of the detected organic emissions arose from fuel pyrolys is which produces white smoke rich in oxygenated organic compounds. Th ese compounds deserve more attention in the assessment of fire impacts on the atmosphere. The compound 2-hydroxyethanal is a significant com ponent of the smoke, and it is reported here for the first time as a p roduct of fires. Most of the observed alkane and ammonia production ac companied visible glowing combustion. NH3 is normally the major nitrog en-containing emission detected from smoldering combustion of biomass, but from some smoldering organic soils, HCN was dominant. Tar condens ed on cool surfaces below the fires accounting for similar to 1% of th e biomass burned, but it was enriched in N by a factor of 6-7 over the parent material, and its possible role in postfire nutrient cycling s hould be further investigated.