Atmospheric ageing of wood fuel combustion emissions and its main organic markers. Primary emissions and secondary aerosol formation potentials: comparisons between different residential stove technologies - VULCAIN Project. Report, April 2018

Biomass burning is in winter a major source of air pollution by particulate matter, especially in France. While primary emissions have already been characterized extensively, only few studies have addressed the aging of these emissions in the atmosphere and large uncertainties remain. Therefore, the objectives of this project was to study, in a smog chamber, the aging of the aerosol emitted by 3 different woodstoves used for residential heating: one unlabeled logwood stoves fabricated in 2000, one 7 stars labeled logwood stoves and one 5 stars labeled pellet burner. A specific focus was made on the Secondary Organic Aerosol (SOA) production potential and on the modification of the chemical fingerprint of the emissions at the molecular level during their transport in the atmosphere. In terms of primary emissions, the 7 stars logwood stove emits an average of 35 % less fine particles (PM_2.5) than the unlabeled stove (631 mg.kg^-1 versus 986 mg.kg^-1, respectively). Of the three tested stoves, the pellet burner is the most emitting woodstoves with an average PM_2.5 emission factor of 1370 mg.kg^-1, composed of nearly 90% of Black Carbon. The experiments also clearly demonstrated the importance of considering the secondary aerosol production potential (SAPP) in the evaluation of the global impact of a given stove emissions. The organic aerosol concentration can thus be multiplied by a factor up to 7 (ranging from 3.5 to 7.1) for the logwood stoves after an atmospheric residence time equivalent to 5 hours. The SAPP is significantly lower for pellet burner emissions (ranging from 1.5 to 1.9). Thus, considering atmospheric aging, the probability of reducing the global PM_2.5 emissions by a factor of 1.5 by replacing a non-labeled logwood stove by a 7-star labeled logwood stove is estimated at 85%. This probability is 100% if the non-labeled logwood stove is replaced by a pellet stove (labeled 5 stars). The study also further demonstrated the influence of the combustion efficiency on the emissions and implicitly the crucial role of the operator. Atmospheric aging of biomass burning aerosol also highlights 2 remarkable points. First, the abundant formation of nitro-catechols which could be used as markers of SOA produced from biomass combustion emissions. Then, the importance of the volatilization process of levoglucosan, main marker of biomass burning, during the dilution phase, and challenge the pertinence of the degradation rate constant determined previously in smog chamber. Finally, the analysis of the data collected in the Arve valley during winter 2014 shows the prevalence of the biomass combustions sources on both the submicron organic aerosol fraction (> 65%) and volatile organic compounds identified and quantified here (> 55%).Finally, the analysis of the data collected in the Arve valley during winter 2014 shows the prevalence of the biomass combustions sources on both the submicron organic aerosol fraction (> 65%) and volatile organic compounds identified and quantified here (> 55%). (authors)