Quantification of Monosaccharide Anhydrides by Liquid Chromatography Combined with Mass Spectrometry: Application to Aerosol Samples from an Urban and a Suburban Site Influenced by Small-Scale Wood Burning

Abstract

Levels of the monosaccharide anhydride (MA) levoglucosan and its isomeric compounds galactosan and mannosan were quantified in the PM10 fraction (particulate matter < or = 10 microm in aerodynamic diameter) of ambient aerosols from an urban (Oslo) and a suburban (Elverum) site in Norway, both influenced by small-scale wood burning. MAs are degradation products of cellulose and hemicellulose, and levoglucosan is especially emitted in high concentrations during pyrolysis and combustion of wood, making it a potential tracer of primary particles emitted from biomass burning. MAs were quantified using a novel high-performance liquid chromatography/ high-resolution mass spectrometry-time of flight method. This approach distinguishes between the isomeric compounds of MAs and benefits from the limited sample preparation required before analysis, and no extensive derivatization step is needed. The highest concentrations of levogucosan, galactosan, and mannosan (sigmaMA) were recorded in winter because of wood burning for residential heating (sigmaMA(MAX) = 1,240 ng m(-3)). This finding was substantiated by a relatively high correlation (R2 = 0.64) between the levoglucosan concentration and decreasing ambient temperature. At the suburban site, sigmaMA accounted for 3.1% of PM10, whereas the corresponding level at the urban site was 0.6%. The mass size distribution of MAs associated with atmospheric aerosols was measured using a Berner cascade impactor. The size distribution was characterized with a single mode at 561 nm. Ninety-five percent of the mass concentration of the MAs was found to be associated with particles < 2 micro.m. A preliminary attempt to estimate the contribution of wood burning to the mass concentration of PM10 in Oslo using levoglucosan as a tracer indicates that 24% comes from wood burning. This is approximately a factor of 2 lower than estimated by the AirQUIS dispersion model.

Carbonaceous aerosols in Norwegian urban areas

“…The intercept of the leastsquare fit (TC p versus LG) is slightly negative on the TC p axis, which implies that the changes in levoglucosan alone are more than sufficient to explain the variations in TC p . The very high relationship for the PM 10 fraction is somewhat surprising, since Yttri et al (2005) have shown previously that about 95% of levoglucosan is found in the PM 2.5 fraction. As the fine fraction accounts for 77% of TC p (Table 4), much of the high correlation will be due to this fraction.…”

The formation, properties and impact of secondary organic aerosol: current and emerging issues

“…More than 20 years ago, the pioneering study of Currie et al (1986) found that residential wood combustion accounted for on average 65% of carbon in fine aerosol at the town of Elverum 120 km north of Oslo during wintertime. Several recent studies have confirmed the dominance of wood combustion in wintertime for many areas (Yttri et al, 2005Glasius et al, 2006;Hedberg et al, 2006;Hellén et al, 2008a;Saarikoski et al, 2008), although recent results from Gothenburg in Southern Sweden showed a lower wood-burning signal (Szidat et al, 2009). Very few summertime data are available, but Szidat et al (2009) also found that Gothenburg showed a similar OC composition to that found for Zürich.…”

Quantifying black carbon from biomass burning by means of levoglucosan – a one-year time series at the Arctic observatory Zeppelin

“…Aerosol particles emitted from biomass burning are found to reside in the fine particle size fraction (e.g., Kleeman et al, 1999;Hedberg et al, 2006;Yttri et al, 2005). Hence, we regard the PM 2.5 cut-off size of the co-located high-volume sampler, which was used when the Digitel high-volume sampler (PM 10 inlet) was out of order due to maintenance, as a minor uncertainty.…”