Wood smoke particles

Guo and Kamens (1991) describe a system for studying gas-particle reactions on the surfaces of combustion aerosols in which they report a half-life of 80 h for high loadings of particle-bound BaP in wood smoke particles reacting with 200 ppb of NOz in air. 

This is consistent with a study by Feilberg and Nielsen (1999b), who investigated the influence of other aerosol components on the photodegradation rates of representative particle-associated nitro-PAHs in a model system consisting of the nitro-PAH dissolved in cyclohexane along with various known constituents of diesel exhaust and wood smoke particles. These cosolutes included PAHs, substituted phenols, hydroxy-PAHs, oxy-PAHs, and substituted benzaldehydes. 

Kamens, R., D. Bell, A. Dietrich, J. Perry, R. Goodman, L. Claxton, and S. Tejada, Mutagenic Transformation of Dilute Wood Smoke Systems in the Presence of Ozone and Nitrogen Dioxide. Analysis of Selected High-Pressure Liquid Chromatography Fractions from Wood Smoke Particle Extracts, Environ. Sci. Technol., 19, 63-69 (1985). 

Rau, J. A. (1989) Composition and size distribution of residual wood smoke particles. Aerosol Sci. Technoi, 10, 181-192. 

Smoke - Smoke constitutes fine, solid, gasbome matters that are products of incomplete combustion of organics (wood, coal, tobacco). Smoke particles are extremely small, ranging in size from less than 0.01 /im to 1 /im. 

Application of a combination of all of these approaches can be particularly powerful when the requisite input data are available. For example, Malm and Gebhart (1997) used a combination of these source apportionment techniques to show that in the Grand Canyon area, about 50% of the sulfur in particles was associated with sources that also emitted Se and hence was attributed to coal-fired power plants in the region. A strong association with bromine was also found, suggesting that wood smoke was also a significant source of sulfur in this region. 

As with the Salmonella reversion assay, this shortterm test is conducted both without (— PMS) and with metabolic activation produced by addition of post-mitochondrial supernatant containing rat liver enzymes ( + PMS). These terms are equivalent to — S9 and + S9 in the Ames reversion assay we use the latter designation for both types of bacterial assays. A more sensitive micro-forward mutation bioassay using this TM677 strain to determine the mutagenicity of indoor air particles, including ETS and wood smoke, is described by Lewtas et al. (1987). 

We discuss in this section four key aspects of heterogeneous reactions (1) theoretical and experimental structure and reactivity relationships (2) held measurements of relative and absolute PAH decay rates in near-source ambient air and during downwind transport (3) laboratory studies of the photolysis/photo-oxidation and gas-particle interactions with 03 and NOz of key 4- and 6-ring PAHs adsorbed on model substrates or ambient aerosols and (4) environmental chamber studies of the reactions of such PAHs associated with several physically and chemically different kinds of combustion-generated aerosols (e.g., diesel soot, wood smoke, and coal fly ash). Where such data are available, we also briefly consider some toxicological ramifications of these reactions. 

In their thoughtful 1983 review, Nielsen and coworkers noted that particles of diesel soot or wood smoke can absorb significant amounts of water. Thus, they suggested that the most plausible mechanism(s) for nitration (and possibly other electrophilic reactions) of particle-associated PAHs in ambient air may involve reactions both in a liquid film and on solid surfaces and that fundamental laboratory studies of the rates, products, and mechanisms of PAHs in polar solvents would be atmospherically relevant for reactions in the liquid films. Based on this, they proposed a classification scheme for the reactivities of key PAHs in electrophilic reactions, which was subsequently described in detail (Nielsen, 1984). 

FIGURE 10.28 Rates of photodegradation of benzo[a]pyrene (Class II reactivity see Table 10.30) and benzole]pyrene (Class V) in irradiated solutions of hexadecane or a mixture of methoxyphenols that are representative of important classes of organics present in particles of diesel soot and wood smoke, respectively (adapted from McDow et al., 1994). 

However, when H-atom-donating cosolutes, e.g., certain phenols, were added, the photodegradation rates of both 1-nitropyrene and 3-nitrofluoranthene increased. In this case, the reaction occurred via H-atom abstraction from the phenol by the electronically excited nitro-PAHs. Feilberg and Nielsen concluded that the photodegradation of nitro-PAHs on both diesel particles and wood smoke proceeds primarily by radical formation. However, H-atom abstraction by the excited triplet states of 1-nitropyrene and 2-nitrofluoranthene may also contribute. 

FIGURE 11.70 Positive and negative ions detected in a single particle from wood smoke generated in the laboratory (adapted from Gard et at., 1997). 

Wood smoke Light-colored particles of cellulose ash, pleasant aromatic odor. Smoke from special kinds of wood (e.g.. hickory, maple) is used to cure ham, fish, etc., also to preserve crude robber. 

Smoke A cloud of particles produced by some sort of oxidation process such as burning. The optical density is presupposed. Generally, smokes are considered to have an organic origin and typically come from coal, oil, wood, or other carbonaceous fuels. Smoke particles are in the same size range as fume particles. 

Tan YL, Quanci JF, Borys RD. et al. 1992. Polycyclic aromatic hydrocarbons in smoke particles from wood and duff burning. Atmos Environ 26(6) 1177-1181. 

Compounds that evaporate may remain in the gas phase but can also distribute onto particles in the atmosphere. Other compounds may be released on particles such as the polynuclear aromatic hydrocarbons produced in the combustion of diesel fuel or in wood smoke. It is of interest to explore how compounds distribute between the particle and the vapor phase since this will influence their environmental behavior. Distribution onto a particle will enhance the potential for wet or dry deposition, major transport processes for moving compounds to surface water or onto vegetation. Compounds in the vapor phase will be subject to a range of photoinduced transformation processes, but how susceptible are compounds sorbed on particles ... 

Samat et al. 2008 27 hospitals in Atlanta area Time series smdy (daily emergency department admissions) In factor analysis, following factors identified gasoline, diesel, wood smoke, soil, secondary sulfate 1 and 2, cement kiln, railroad, and metal processing. Particles include EC, OC, Se, nitrate, sulfate, K and Zn In factor analyses, emergency department admissions for cardiovascular disease associated with sources of carbonaceous emissions (gasoline, diesel, wood smoke). PM components associated with CVD hospital admissions were EC, OC, and K (a tracer for wood smoke). Sulfate, nitrate, Se, and Zn not associated. 

---