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

• Published in: Atmospheric Chemistry and Physics
• Main Authors: 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.
• Format: Text
• Language: English
• Published: 2019
• Subjects: Alaska; Siberia
• Online Access: https://doi.org/10.5194/acp-19-14173-2019; https://www.atmos-chem-phys.net/19/14173/2019/

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) <math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>=</mo><mn mathvariant="normal">0.82</mn><mo>±</mo><mn mathvariant="normal">0.08</mn></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="66pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="8f12f3d4d3810e9be6b29cbe44c42662"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-14173-2019-ie00001.svg" width="66pt" height="10pt" src="acp-19-14173-2019-ie00001.png"/></svg:svg> ). Average fuel-based EF <math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><msub><mi/><mrow class="chem"><msub><mi mathvariant="normal">CO</mi><mn mathvariant="normal">2</mn></msub></mrow></msub></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="18pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="304cc11e101ca2ea948d7e1f8bd141ca"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-14173-2019-ie00002.svg" width="18pt" height="10pt" src="acp-19-14173-2019-ie00002.png"/></svg:svg> (carbon dioxide) are highest (1400 ± 38 g kg −1 ) and lowest (1073 ± 63 g kg −1 ) for the Alaskan and Russian peats, respectively. EF CO (carbon monoxide) and EF <math xmlns="http://www.w3.org/1998/Math/MathML" id="M10" display="inline" overflow="scroll" dspmath="mathml"><msub><mi/><mrow class="chem"><msub><mi mathvariant="normal">CH</mi><mn mathvariant="normal">4</mn></msub></mrow></msub></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="17pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="9e31c76b8daf1e55847267acb0ad825e"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-14173-2019-ie00003.svg" width="17pt" height="10pt" src="acp-19-14173-2019-ie00003.png"/></svg:svg> (methane) are ∼12 %–15 % and ∼0.3 %–0.9 % of EF <math xmlns="http://www.w3.org/1998/Math/MathML" id="M13" display="inline" overflow="scroll" dspmath="mathml"><msub><mi/><mrow class="chem"><msub><mi mathvariant="normal">CO</mi><mn mathvariant="normal">2</mn></msub></mrow></msub></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="18pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="b1d82231c8451aea75badcff7793dd11"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-14173-2019-ie00004.svg" width="18pt" height="10pt" src="acp-19-14173-2019-ie00004.png"/></svg:svg> , in the range of 157–171 and 3–10 g kg −1 , respectively. EFs for nitrogen species are at the same magnitude as EF <math xmlns="http://www.w3.org/1998/Math/MathML" id="M15" display="inline" overflow="scroll" dspmath="mathml"><msub><mi/><mrow class="chem"><msub><mi mathvariant="normal">CH</mi><mn mathvariant="normal">4</mn></msub></mrow></msub></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="17pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="7962a24cd06a5d2ea59d07ae0b7afe6c"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-14173-2019-ie00005.svg" width="17pt" height="10pt" src="acp-19-14173-2019-ie00005.png"/></svg:svg> , with an average of 5.6 ± 4.8 and 4.7 ± 3.1 g kg −1 for EF <math xmlns="http://www.w3.org/1998/Math/MathML" id="M19" display="inline" overflow="scroll" dspmath="mathml"><msub><mi/><mrow class="chem"><msub><mi mathvariant="normal">NH</mi><mn mathvariant="normal">3</mn></msub></mrow></msub></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="17pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="89d5a246426b5274ba0a3336503bb5a0"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-14173-2019-ie00006.svg" width="17pt" height="10pt" src="acp-19-14173-2019-ie00006.png"/></svg:svg> (ammonia) and EF HCN (hydrogen cyanide); 1.9±1.1 g kg −1 for EF <math xmlns="http://www.w3.org/1998/Math/MathML" id="M23" display="inline" overflow="scroll" dspmath="mathml"><msub><mi/><mrow class="chem"><msub><mi mathvariant="normal">NO</mi><mi>x</mi></msub></mrow></msub></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="18pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="b21a03ea8237bdbfe34ba194ef5dc514"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-14173-2019-ie00007.svg" width="18pt" height="10pt" src="acp-19-14173-2019-ie00007.png"/></svg:svg> (nitrogen oxides); and 2.4±1.4 and 2.0 ± 0.7 g kg −1 for EF <math xmlns="http://www.w3.org/1998/Math/MathML" id="M27" display="inline" overflow="scroll" dspmath="mathml"><msub><mi/><mrow class="chem"><msub><mi mathvariant="normal">NO</mi><mi>y</mi></msub></mrow></msub></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="17pt" height="11pt" class="svg-formula" dspmath="mathimg" md5hash="ab0dcf94c5a54bf93d1693e16ebe5a7b"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-14173-2019-ie00008.svg" width="17pt" height="11pt" src="acp-19-14173-2019-ie00008.png"/></svg:svg> (total reactive nitrogen) and EF <math xmlns="http://www.w3.org/1998/Math/MathML" id="M28" display="inline" overflow="scroll" dspmath="mathml"><msub><mi/><mrow class="chem"><msub><mi mathvariant="normal">N</mi><mn mathvariant="normal">2</mn></msub><mi mathvariant="normal">O</mi></mrow></msub></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="18pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="b817462035d1de7587e2993e52f26d03"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-14173-2019-ie00009.svg" width="18pt" height="10pt" src="acp-19-14173-2019-ie00009.png"/></svg:svg> (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 EF <math xmlns="http://www.w3.org/1998/Math/MathML" id="M31" display="inline" overflow="scroll" dspmath="mathml"><msub><mi/><mrow><msub><mi mathvariant="normal">PM</mi><mn mathvariant="normal">2.5</mn></msub></mrow></msub></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="23pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="2c8e86879956b3a04fcf5d9bd38fcf40"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-14173-2019-ie00010.svg" width="23pt" height="10pt" src="acp-19-14173-2019-ie00010.png"/></svg:svg> varied by > 4-fold (14–61 g kg −1 ) without appreciable changes between fresh and aged emissions. The majority of EF <math xmlns="http://www.w3.org/1998/Math/MathML" id="M33" display="inline" overflow="scroll" dspmath="mathml"><msub><mi/><mrow><msub><mi mathvariant="normal">PM</mi><mn mathvariant="normal">2.5</mn></msub></mrow></msub></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="23pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="8ab96d3c0adcd25ec010e82d71b755bc"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-14173-2019-ie00011.svg" width="23pt" height="10pt" src="acp-19-14173-2019-ie00011.png"/></svg:svg> consists of EF OC (organic carbon), with EF OC ∕ EF <math xmlns="http://www.w3.org/1998/Math/MathML" id="M37" display="inline" overflow="scroll" dspmath="mathml"><msub><mi/><mrow><msub><mi mathvariant="normal">PM</mi><mn mathvariant="normal">2.5</mn></msub></mrow></msub></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="23pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="2aef2c8de4117568d536da75b1d60680"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-14173-2019-ie00012.svg" width="23pt" height="10pt" src="acp-19-14173-2019-ie00012.png"/></svg:svg> ratios in the range of 52 %–98 % for fresh emissions and ∼14 %–23 % degradation after aging. Reductions of EF OC ( ∼7 –9 g kg −1 ) after aging are most apparent for boreal peats, with the largest degradation in low-temperature OC1 that evolves at < 140 ∘ C, indicating the loss of high-vapor-pressure semivolatile organic compounds upon aging. The highest EF Levoglucosan is found for Russian peat ( ∼16 g kg −1 ), with ∼35 %–50 % degradation after aging. EFs for water-soluble OC (EF WSOC ) account for ∼20 %–62 % of fresh EF OC . The majority (> 95 %) of the total emitted carbon is in the gas phase, with 54 %–75 % CO 2 , 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 <math xmlns="http://www.w3.org/1998/Math/MathML" id="M52" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>∼</mo><mn mathvariant="normal">1</mn><mo>/</mo><mn mathvariant="normal">3</mn></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="31pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="be3917116a757c94c03299ca4ff6f78d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-14173-2019-ie00013.svg" width="31pt" height="14pt" src="acp-19-14173-2019-ie00013.png"/></svg:svg> 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 NH 3 and 9.5 % as HCN. N 2 O and NO y constituted 5.7 % and 2.9 % of consumed fuel nitrogen. EFs from this study can be used to refine current emission inventories.