Gaseous, PM 2.5 mass, and speciated emission factors from laboratory chamber peat combustion

Watson, John G.; Cao, Junji; Chen, L.-W. Antony; Wang, Qiyuan; Tian, Jie; Wang, Xiaoliang; Gronstal, Steven; Ho, Steven Sai Hang; Watts, Adam C.; Chow, Judith C.

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) inline-formula M3inlinescrollmathml = normal 0.82 ± normal 0.08 66pt10ptsvg-formulamathimg8f12f3d4d3810e9be6b29cbe44c42662 acp-19-14173-2019-ie00001.svg66pt10ptacp-19-14173-2019-ie00001.png ). Average fuel-based EFinline-formula M4inlinescrollmathml chem normal CO normal 2 18pt10ptsvg-formulamathimg304cc11e101ca2ea948d7e1f8bd141ca acp-19-14173-2019-ie00002.svg18pt10ptacp-19-14173-2019-ie00002.png (carbon dioxide) are highest (1400 inline-formula± 38 g kginline-formula−1) and lowest (1073 inline-formula± 63 g kginline-formula−1) for the Alaskan and Russian peats, respectively. EFinline-formulaCO (carbon monoxide) and EFinline-formula M10inlinescrollmathml chem normal CH normal 4 17pt10ptsvg-formulamathimg9e31c76b8daf1e55847267acb0ad825e acp-19-14173-2019-ie00003.svg17pt10ptacp-19-14173-2019-ie00003.png (methane) are inline-formula∼12 %–15 % and inline-formula∼0.3 %–0.9 % of EFinline-formula M13inlinescrollmathml chem normal CO normal 2 18pt10ptsvg-formulamathimgb1d82231c8451aea75badcff7793dd11 acp-19-14173-2019-ie00004.svg18pt10ptacp-19-14173-2019-ie00004.png , in the range of 157–171 and 3–10 g kginline-formula−1, respectively. EFs for nitrogen species are at the same magnitude as EFinline-formula M15inlinescrollmathml chem normal CH normal 4 17pt10ptsvg-formulamathimg7962a24cd06a5d2ea59d07ae0b7afe6c acp-19-14173-2019-ie00005.svg17pt10ptacp-19-14173-2019-ie00005.png , with an average of 5.6 inline-formula± 4.8 and 4.7 inline-formula± 3.1 g kginline-formula−1 for EFinline-formula M19inlinescrollmathml chem normal NH normal 3 17pt10ptsvg-formulamathimg89d5a246426b5274ba0a3336503bb5a0 acp-19-14173-2019-ie00006.svg17pt10ptacp-19-14173-2019-ie00006.png (ammonia) and EFinline-formulaHCN (hydrogen cyanide); inline-formula1.9±1.1 g kginline-formula−1 for EFinline-formula M23inlinescrollmathml chem normal NO x 18pt10ptsvg-formulamathimgb21a03ea8237bdbfe34ba194ef5dc514 acp-19-14173-2019-ie00007.svg18pt10ptacp-19-14173-2019-ie00007.png (nitrogen oxides); and inline-formula2.4±1.4 and 2.0 inline-formula± 0.7 g kginline-formula−1 for EFinline-formula M27inlinescrollmathml chem normal NO y 17pt11ptsvg-formulamathimgab0dcf94c5a54bf93d1693e16ebe5a7b acp-19-14173-2019-ie00008.svg17pt11ptacp-19-14173-2019-ie00008.png (total reactive nitrogen) and EFinline-formula M28inlinescrollmathml chem normal N normal 2 normal O 18pt10ptsvg-formulamathimgb817462035d1de7587e2993e52f26d03 acp-19-14173-2019-ie00009.svg18pt10ptacp-19-14173-2019-ie00009.png (nitrous oxide).

An oxidation flow reactor (OFR) was used to simulate atmospheric aging times of inline-formula∼2 and inline-formula∼7 d to compare fresh (upstream) and aged (downstream) emissions. Filter-based EFinline-formula M31inlinescrollmathml normal PM normal 2.5 23pt10ptsvg-formulamathimg2c8e86879956b3a04fcf5d9bd38fcf40 acp-19-14173-2019-ie00010.svg23pt10ptacp-19-14173-2019-ie00010.png varied by > 4-fold (14–61 g kginline-formula−1) without appreciable changes between fresh and aged emissions. The majority of EFinline-formula M33inlinescrollmathml normal PM normal 2.5 23pt10ptsvg-formulamathimg8ab96d3c0adcd25ec010e82d71b755bc acp-19-14173-2019-ie00011.svg23pt10ptacp-19-14173-2019-ie00011.png consists of EFinline-formulaOC (organic carbon), with EFinline-formulaOCinline-formula∕ EFinline-formula M37inlinescrollmathml normal PM normal 2.5 23pt10ptsvg-formulamathimg2aef2c8de4117568d536da75b1d60680 acp-19-14173-2019-ie00012.svg23pt10ptacp-19-14173-2019-ie00012.png ratios in the range of 52 %–98 % for fresh emissions and inline-formula∼14 %–23 % degradation after aging. Reductions of EFinline-formulaOC (inline-formula∼7–9 g kginline-formula−1) after aging are most apparent for boreal peats, with the largest degradation in low-temperature OC1 that evolves at < 140 inline-formulaC, indicating the loss of high-vapor-pressure semivolatile organic compounds upon aging. The highest EFinline-formulaLevoglucosan is found for Russian peat (inline-formula∼16 g kginline-formula−1), with inline-formula∼35 %–50 % degradation after aging. EFs for water-soluble OC (EFinline-formulaWSOC) account for inline-formula∼20 %–62 % of fresh EFinline-formulaOC.

The majority (> 95 %) of the total emitted carbon is in the gas phase, with 54 %–75 % inline-formulaCO2, followed by 8 %–30 % CO. Nitrogen in the measured species explains 24 %–52 % of the consumed fuel nitrogen, with an average of 35 inline-formula± 11 %, consistent with past studies that report inline-formula M52inlinescrollmathml normal 1 / normal 3 31pt14ptsvg-formulamathimgbe3917116a757c94c03299ca4ff6f78d acp-19-14173-2019-ie00013.svg31pt14ptacp-19-14173-2019-ie00013.png to inline-formula2∕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 inline-formulaNH3 and 9.5 % as HCN. inline-formulaN2O and inline-formulaNOy constituted 5.7 % and 2.9 % of consumed fuel nitrogen. EFs from this study can be used to refine current emission inventories.

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Watson, John G. / Cao, Junji / Chen, L.-W. Antony / et al: Gaseous, PM2.5 mass, and speciated emission factors from laboratory chamber peat combustion. 2019. Copernicus Publications.

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Rechteinhaber: John G. Watson et al.

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