Regionally sourced bioaerosols drive high-temperature ice nucleating particles in the Arctic.

Primary biological aerosol particles (PBAP) play an important role in the climate system, facilitating the formation of ice within clouds, consequently PBAP may be important in understanding the rapidly changing Arctic. Within this work, we use single-particle fluorescence spectroscopy to identify and quantify PBAP at an Arctic mountain site, with transmission electronic microscopy analysis supporting the presence of PBAP. We find that PBAP concentrations range between 10-3-10-1 L-1 and peak in summer. Evidences suggest that the terrestrial Arctic biosphere is an important regional source of PBAP, given the high correlation to air temperature, surface albedo, surface vegetation and PBAP tracers. PBAP clearly correlate with high-temperature ice nucleating particles (INP) (>-15 °C), of which a high a fraction (>90%) are proteinaceous in summer, implying biological origin. These findings will contribute to an improved understanding of sources and characteristics of Arctic PBAP and their links to INP.

Equal abundance of summertime natural and wintertime anthropogenic Arctic organic aerosols.

Aerosols play an important yet uncertain role in modulating the radiation balance of the sensitive Arctic atmosphere. Organic aerosol is one of the most abundant, yet least understood, fractions of the Arctic aerosol mass. Here we use data from eight observatories that represent the entire Arctic to reveal the annual cycles in anthropogenic and biogenic sources of organic aerosol. We show that during winter, the organic aerosol in the Arctic is dominated by anthropogenic emissions, mainly from Eurasia, which consist of both direct combustion emissions and long-range transported, aged pollution. In summer, the decreasing anthropogenic pollution is replaced by natural emissions. These include marine secondary, biogenic secondary and primary biological emissions, which have the potential to be important to Arctic climate by modifying the cloud condensation nuclei properties and acting as ice-nucleating particles. Their source strength or atmospheric processing is sensitive to nutrient availability, solar radiation, temperature and snow cover. Our results provide a comprehensive understanding of the current pan-Arctic organic aerosol, which can be used to support modelling efforts that aim to quantify the climate impacts of emissions in this sensitive region.

Health effects of residential wood smoke particles: the importance of combustion conditions and physicochemical particle properties.

BACKGROUND: Residential wood combustion is now recognized as a major particle source in many developed countries, and the number of studies investigating the negative health effects associated with wood smoke exposure is currently increasing. The combustion appliances in use today provide highly variable combustion conditions resulting in large variations in the physicochemical characteristics of the emitted particles. These differences in physicochemical properties are likely to influence the biological effects induced by the wood smoke particles. OUTLINE: The focus of this review is to discuss the present knowledge on physicochemical properties of wood smoke particles from different combustion conditions in relation to wood smoke-induced health effects. In addition, the human wood smoke exposure in developed countries is explored in order to identify the particle characteristics that are relevant for experimental studies of wood smoke-induced health effects. Finally, recent experimental studies regarding wood smoke exposure are discussed with respect to the applied combustion conditions and particle properties. CONCLUSION: Overall, the reviewed literature regarding the physicochemical properties of wood smoke particles provides a relatively clear picture of how these properties vary with the combustion conditions, whereas particle emissions from specific classes of combustion appliances are less well characterised. The major gaps in knowledge concern; (i) characterisation of the atmospheric transformations of wood smoke particles, (ii) characterisation of the physicochemical properties of wood smoke particles in ambient and indoor environments, and (iii) identification of the physicochemical properties that influence the biological effects of wood smoke particles.

Phthalate levels in Norwegian indoor air related to particle size fraction.

Phthalates are found in numerous consumer products, including interior materials like polyvinyl chloride (PVC). Several studies have identified phthalates in indoor air. A recent case-control study demonstrated associations between allergic symptoms in children and the concentration of phthalates in dust collected from their homes. Here we have analyzed the content of selected phthalates in particulate matter (PM): PM(10) and PM(2.5) filter samples collected in 14 different indoor environments. The results showed the presence of the phthalates di-n-butyl phthalate (DBP), butyl benzyl phthalate (BBP), dicyclohexyl phthalate (DCHP) and diethyl hexyl phthalate (DEHP) in the samples. The dominating phthalate in both PM(10) and PM(2.5) samples from all locations was DBP. More than a 10-fold variation in the mean concentration of total phthalates between sampling sites was observed. The highest levels of total phthalates were detected in one children's room, one kindergarten, in two primary schools, and in a computer room. The relative contribution of total phthalates in PM(10) and PM(2.5) was 1.1 +/- 0.3% for both size fractions. The contribution of total phthalates in PM(2.5) to total phthalates in PM(10) ranged from 23-81%, suggesting different sources. Of the phthalates that were analyzed in the PM material, DBP was found to be the major phthalate in rubber from car tyres. However, our analyses indicate that tyre wear was of minor importance for indoor levels of both DBP as well as total phthalates. Overall, these results support the notion that inhalation of indoor PM contributes to the total phthalate exposure.

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.

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.

Determination of monosaccharide anhydrides in atmospheric aerosols by use of high-performance liquid chromatography combined with high-resolution mass spectrometry.

A novel method for determination of the monosaccharide anhydrides (MAs) levoglucosan, mannosan, and galactosan in atmospheric aerosols has been developed. The method is based on solvent extraction of aerosol filter samples and chemical analysis performed with high-performance liquid chromatography (HPLC) combined with time-of-flight high-resolution mass spectrometry. The MAs were separated on two series connected 2.1 mm x150 mm reversed-phase HPLC columns and identified by negative electrospray ionization mass spectrometry using the m/z 113, 129, and 161 as monitoring ions. The limit of quantification (LOQ) at S/N 10 ranges between 20 and 40 pg for the three isomers. The LOQ can easily be improved. Samples from Elverum (urban background) and Oslo (urban) in Norway were used in validation experiments. Tetrahydrofuran was found to be the most efficient extraction solvent. The choice of solvent is of crucial importance to minimize adsorption to the glassware. Interactions between the MAs and active sites on the quartz filter surface are observed.