Changes in PM<sub>2.5</sub> Peat Combustion Source Profiles with Atmospheric Aging in an Oxidation Flow Reactor

Abstract

24Smoke from laboratory chamber burning of peat fuels from Russia, Siberia, U.S.A. (Alaska 25 and Florida), and Malaysia representing boreal, temperate, subtropical, and tropical regions was 26 sampled before and after passing through a potential aerosol mass-oxidation flow reactor (PAM-27 OFR) to simulate ~2-and 7-day atmospheric aging. Species abundances in PM2.5 between aged 28 and fresh profiles varied by >5 orders of magnitude with two distinguishable clusters: around 29 0.1% for reactive and ionic species and mostly >10 % for carbon. 30Organic carbon (OC) accounted for 58-85 % of PM2.5 mass in fresh profiles with low EC 31 abundance (0.67-4.4 %). After a 7-day aging time, degradation was 20-33 % for OC, with 32 apparent reductions (4-12 %) in low temperature OC1 and OC2 (thermally evolved at 140 and 33 280 °C), implying evaporation of higher vapor pressure semi-volatile organic compounds 34 (SVOCs). Additional losses of OC from 2-to 7-days aging is somewhat offset by the formation 35 of oxygenated organic compounds, as evidenced by the 12-19 % increase in organic mass (OM) 36 to OC ratios. However, the reduction of OM abundances in PM2.5 by 3-18 % after 7 days, 37 reconfirms that volatilization is the main loss mechanism of SVOCs. Although the ammonia 38 (NH3) to PM2.5 ratio rapidly diminished with a 2-day aging time, it represents an intermediate 39 profile -not sufficient for completed OC evaporation, levoglucosan degradation, organic acid 40 oxidation, or secondary inorganic aerosol formation. 41Week-long aging resulted in an increase to ~7-8 % of NH4 + and NO3abundances, but with 42 enhanced degradation of NH3, low temperature OC, and levoglucosan for Siberia, Alaska, and 43 Everglasdes (FL) peats. Elevated levoglucosan was found for Russian peats, accounting for 35-44 39 % and 20-25 % of PM2.5 mass for fresh and aged profiles, respectively. Abundances of water-45 soluble organic carbon (WSOC) in PM2.5 was >2-fold higher in fresh Russian (37.0 ± 2.7 %) than 46 Malaysian (14.6 ± 0.9 %) peats. While Russian peat OC emissions are largely water-soluble, 47to-particle partitioning of semi-volatilized species, gas-phase oxidation, and particle volatilization 54 to achieve representative source profiles for regional-scale source apportionment. 55 56 Keywords: fresh and aged source profiles, atmospheric aging, organic mass, organic carbon, 57 levoglucosan, oxidation flow reactor (OFR) 58

Chemical and Mineralogical Composition of Soot and Ash from the Combustion of Peat Briquettes in Household Boilers

“…The imported briquettes from Ukraine and Belarus are characterized by the low content of ash of up to 10%. The concentrations of the major elements C, H, N, S and O are similar, and the differences can be found in the concentrations of organic compounds in the relationship with the conditions of peat origin [13].…”

“…While peat represents a valuable raw material, it causes difficult environmental problems related to the smouldering of peat bogs. Peat fires appear to be a global threat with considerable atmospheric, climatic, economic, social, ecological, and health impacts [13]. From the point of view of the fuel consumption, the fires and smouldering of peat represent the largest fires on Earth.…”

Gaseous, PM<sub>2.5</sub> Mass, and Speciated Emission Factors from Laboratory Chamber Peat Combustion

“…Citric acid and sodium chloride impregnated cellulose-fiber filters placed behind the Teflon-membrane and quartz-fiber filters, respectively, acquired NH3 as NH4 + and nitric acid (HNO3) as volatilized nitrate, respectively, with analysis by ion chromatography. Details on chemical analyses can be found in Chow et al (2019).…”

“…is calculated from the filter samples. Chow et al (2019) present the species abundances from this study in PM2.5 mass based on the average fresh and aged profiles, separated by 2-and 7-day photochemical aging times simulated with the oxidation flow reactor (Aerodyne, 2019). The same approach is used in Table S6 to compare fresh and aged particle EFs.…”

Wildfire and prescribed burning impacts on air quality in the United States

“…Recent peat-burning emissions tests (Chow et al 2019a;Watson et al 2019) illustrated how multipollutant emission aging from biomass burning and other sources can be simulated with an oxidation flow reactor (OFR) (Cao et al 2020). The OFR is like a miniature smog chamber that irradiates an emissions mixture with high intensity ultraviolet radiation to simulate photochemical changes during pollution transport and aging.…”