Gaseous, PM2.5 mass, and speciated emission factors from laboratory chamber peat combustion

_abs Peat fuels representing four biomes of boreal (western Russia and Siberia), temperate (northern Alaska, USA), subtropical (northern and southern Florida, USA), and tropical (Borneo, Malaysia) regions were burned in a laboratory chamber to determine gas and particle emission factors (EFs). Tests with 25% fuel moisture were conducted with predominant smoldering combustion conditions (average modified combustion efficiency (MCE) D 0:82± 0:08). Average fuel-based EFCO2 (carbon dioxide) are highest (1400±38 g kg^-1) and lowest (1073±63 g kg^-1) for the Alaskan and Russian peats, respectively. EFCO (carbon monoxide) and EFCH4 (methane) are ∼ 12 %–15% and ∼ 0:3 %–0.9% of EFCO2 , in the range of 157–171 and 3– 10 g kg^-1, respectively. EFs for nitrogen species are at the same magnitude as EFCH4 , with an average of 5.6±4.8 and 4.7±3.1 g kg^-1 for EFNH3 (ammonia) and EFHCN (hydrogen cyanide); 1:9±1:1 g kg^-1 for EFNOx (nitrogen oxides); and 2:4±1:4 and 2.0±0.7 g kg^-1 for EFNOy (total reactive nitrogen) and EFN2O (nitrous oxide). An oxidation flow reactor (OFR) was used to simulate atmospheric aging times of ∼ 2 and ∼ 7 d to compare fresh (upstream) and aged (downstream) emissions. Filter-based EFPM2:5 varied by > 4-fold (14–61 g kg^-1) without appreciable changes between fresh and aged emissions. The majority of EFPM2:5 consists of EFOC (organic carbon), with EFOC = EFPM2:5 ratios in the range of 52 %–98% for fresh emissions and ∼ 14 %–23% degradation after aging. Reductions of EFOC (∼ 7–9 g kg^-1) after aging are most apparent for boreal peats, with the largest degradation in lowtemperature OC1 that evolves at < 140 °C, indicating the loss of high-vapor-pressure semivolatile organic compounds upon aging. The highest EFLevoglucosan is found for Russian peat (∼ 16 g kg^-1), with ∼ 35 %–50% degradation after aging. EFs for water-soluble OC (EFWSOC) account for ∼ 20 %–62% of fresh EFOC. The majority (> 95 %) of the total emitted carbon is in the gas phase, with 54 %–75% CO2, followed by 8 %–30% CO. Nitrogen in the measured species explains 24 %–52% of the consumed fuel nitrogen, with an average of 35±11 %, consistent with past studies that report ∼ 1=3 to 2=3 of the fuel nitrogen measured in biomass smoke. The majority (> 99 %) of the total emitted nitrogen is in the gas phase, with an average of 16.7% as NH3 and 9.5% as HCN. N2O and NOy constituted 5.7% and 2.9% of consumed fuel nitrogen. EFs from this study can be used to refine current emission inventories.