The contribution of biomass combustion to ambient fine particle concentrations in the United States

Biomass combustion is an important source of fine particle emissions to the atmosphere. According to USEPA emissions inventories for the year 1995, approximately 20% of total primary PM_2.5 emissions come from biomass combustion sources. As an alternative to inventory data such as this, source apportionment with chemical mass balance receptor models can determine the contribution of different fine particle source types to a particular ambient fine particle sample. The identification of individual organic compounds in the fine particle emissions from biomass combustion and other fine particle sources provides a rich source of potential molecular tracers that can be used in apportionment calculations.; A series of experiments were conducted to characterize the fine particle emissions from the following biomass combustion sources: residential wood combustion in fireplaces, non-catalytic wood stoves, and catalytic wood stoves; the prescribed burning of foliar fuels; and the open burning of agricultural waste. Results include emission factors for particle mass, organic and elemental carbon, ionic species, selected elements, and over 200 individual organic compounds as determined by GC/MS analysis. The cellulose pyrolysis product, levoglucosan, was emitted from all of the biomass combustion sources and serves as a unique tracer for biomass combustion in general. Substituted syringols were emitted primarily from hardwood combustion, and resin acids were emitted exclusively from the burning of softwoods. Fine particle emission factors are lower and elemental carbon and PAH emissions are higher from wood stoves than from fireplaces. The burning of foliar fuels produces more alkanoic acids than wood combustion due to the higher concentration of plant waxes in the foliage.; The data from the residential wood combustion source tests were used in a chemical mass balance receptor model to determine the contribution of biomass combustion to ambient fine particle concentrations throughout the United States. Ambient samples collected as part of the IMPROVE and other sampling networks were combined into seasonal composite samples and analyzed for important molecular markers of biomass combustion and other fine particle sources. The resulting national map provides seasonal and geographical information on the significance of biomass combustion as a fine particle source in the United States.