scholarly journals Changes in PM<sub>2.5</sub> peat combustion source profiles with atmospheric aging in an oxidation flow reactor

2019 ◽  
Vol 12 (10) ◽  
pp. 5475-5501 ◽  
Author(s):  
Judith C. Chow ◽  
Junji Cao ◽  
L.-W. Antony Chen ◽  
Xiaoliang Wang ◽  
Qiyuan Wang ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Source Apportionment ◽  
Flow Reactor ◽  
Regional Scale ◽  
Ionic Species ◽  
Atmospheric Modeling ◽  
Water Soluble ◽  
Combustion Source ◽  
Tropical Regions ◽  
Source Profiles

Abstract. Smoke from laboratory chamber burning of peat fuels from Russia, Siberia, the USA (Alaska and Florida), and Malaysia representing boreal, temperate, subtropical, and tropical regions was sampled before and after passing through a potential-aerosol-mass oxidation flow reactor (PAM-OFR) to simulate intermediately aged (∼2 d) and well-aged (∼7 d) source profiles. Species abundances in PM2.5 between aged and fresh profiles varied by several orders of magnitude with two distinguishable clusters, centered around 0.1 % for reactive and ionic species and centered around 10 % for carbon. Organic carbon (OC) accounted for 58 %–85 % of PM2.5 mass in fresh profiles with low elemental carbon (EC) abundances (0.67 %–4.4 %). OC abundances decreased by 20 %–33 % for well-aged profiles, with reductions of 3 %–14 % for the volatile OC fractions (e.g., OC1 and OC2, thermally evolved at 140 and 280 ∘C). Ratios of organic matter (OM) to OC abundances increased by 12 %–19 % from intermediately aged to well-aged smoke. Ratios of ammonia (NH3) to PM2.5 decreased after intermediate aging. Well-aged NH4+ and NO3- abundances increased to 7 %–8 % of PM2.5 mass, associated with decreases in NH3, low-temperature OC, and levoglucosan abundances for Siberia, Alaska, and Everglades (Florida) peats. Elevated levoglucosan was found for Russian peats, accounting for 35 %–39 % and 20 %–25 % of PM2.5 mass for fresh and aged profiles, respectively. The water-soluble organic carbon (WSOC) fractions of PM2.5 were over 2-fold higher in fresh Russian peat (37.0±2.7 %) than in Malaysian (14.6±0.9 %) peat. While Russian peat OC emissions were largely water-soluble, Malaysian peat emissions were mostly water-insoluble, with WSOC ∕ OC ratios of 0.59–0.71 and 0.18–0.40, respectively. This study shows significant differences between fresh and aged peat combustion profiles among the four biomes that can be used to establish speciated emission inventories for atmospheric modeling and receptor model source apportionment. A sufficient aging time (∼7 d) is needed to allow gas-to-particle partitioning of semi-volatilized species, gas-phase oxidation, and particle volatilization to achieve representative source profiles for regional-scale source apportionment.

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

2019 ◽  
Author(s):  
Judith C. Chow ◽  
Junji Cao ◽  
L.-W Antony Chen ◽  
Xiaoliang Wang ◽  
Qiyuan Wang ◽  
...  
Keyword(s):  
Low Temperature ◽  
Organic Carbon ◽  
Source Apportionment ◽  
Aging Time ◽  
Organic Compounds ◽  
Flow Reactor ◽  
Atmospheric Modeling ◽  
Water Soluble ◽  
Atmospheric Aging ◽  
Source Profiles

Abstract. Smoke from laboratory chamber burning of peat fuels from Russia, Siberia, U.S.A. (Alaska and Florida), and Malaysia representing boreal, temperate, subtropical, and tropical regions was sampled before and after passing through a potential aerosol mass-oxidation flow reactor (PAM-OFR) to simulate ∼2- and 7-day atmospheric aging. Species abundances in PM2.5 between aged and fresh profiles varied by >5 orders of magnitude with two distinguishable clusters: around 0.1 % for reactive and ionic species and mostly >10 % for carbon. Organic carbon (OC) accounted for 58–85 % of PM2.5 mass in fresh profiles with low EC abundance (0.67–4.4 %). After a 7-day aging time, degradation was 20–33 % for OC, with apparent reductions (4–12 %) in low temperature OC1 and OC2 (thermally evolved at 140 and 280 °C), implying evaporation of higher vapor pressure semi-volatile organic compounds (SVOCs). Additional losses of OC from 2- to 7-days aging is somewhat offset by the formation of oxygenated organic compounds, as evidenced by the 12–19 % increase in organic mass (OM) to OC ratios. However, the reduction of OM abundances in PM2.5 by 3–18 % after 7 days, reconfirms that volatilization is the main loss mechanism of SVOCs. Although the ammonia (NH3) to PM2.5 ratio rapidly diminished with a 2-day aging time, it represents an intermediate profile – not sufficient for completed OC evaporation, levoglucosan degradation, organic acid oxidation, or secondary inorganic aerosol formation. Week-long aging resulted in an increase to ∼7–8 % of NH4+ and NO3− abundances, but with enhanced degradation of NH3, low temperature OC, and levoglucosan for Siberia, Alaska, and Everglasdes (FL) peats. Elevated levoglucosan was found for Russian peats, accounting for 35–39 % and 20–25 % of PM2.5 mass for fresh and aged profiles, respectively. Abundances of water-soluble organic carbon (WSOC) in PM2.5 was >2-fold higher in fresh Russian (37.0 ± 2.7 %) than Malaysian (14.6 ± 0.9 %) peats. While Russian peat OC emissions are largely water-soluble, Malaysian peat emissions are mostly water-insoluble, with WSOC/OC ratios of 0.59–0.71 and 0.18–0.40, respectively. Source profiles can change with aging during transport from source to receptor. This study shows significant differences between fresh and aged peat combustion profiles among the four biomes that can be used to establish speciated emission inventories for atmospheric modeling and receptor model source apportionment. A sufficient aging time (∼one week) is needed to allow gas-to-particle partitioning of semi-volatilized species, gas-phase oxidation, and particle volatilization to achieve representative source profiles for regional-scale source apportionment.

scholarly journals Chemical characterization of fine particular matter in Changzhou, China and source apportionment with offline aerosol mass spectrometry

2016 ◽  
Author(s):  
Zhaolian Ye ◽  
Jiashu Liu ◽  
Aijun Gu ◽  
Feifei Feng ◽  
Yuhai Liu ◽  
...  
Keyword(s):  
Trace Elements ◽  
Organic Matter ◽  
Organic Carbon ◽  
Source Apportionment ◽  
Major Ions ◽  
Chemical Properties ◽  
Chemical Characterization ◽  
Water Soluble ◽  
Traffic Emissions ◽  
Aerosol Mass

Abstract. Knowledge on aerosol chemistry in densely populated regions is critical for reduction of air pollution, while such studies haven't been conducted in Changzhou, an important manufacturing base and polluted city in the Yangtze River Delta (YRD), China. This work, for the first time, performed a thorough chemical characterization on the fine particular matter (PM2.5) samples, collected during July 2015 to April 2016 across four seasons in Changzhou city. A suite of analytical techniques were employed to characterize organic carbon / elemental carbon (OC / EC), water-soluble organic carbon (WSOC), water-soluble inorganic ions (WSIIs), trace elements, and polycyclic aromatic hydrocarbons (PAHs) in PM2.5; in particular, an Aerodyne soot particle aerosol mass spectrometer (SP-AMS) was deployed to probe the chemical properties of water-soluble organic aerosols (WSOA). The average PM2.5 concentrations were found to be 108.3 μg m−3, and all identified species were able to reconstruct ~ 80 % of the PM2.5 mass. The WSIIs occupied about half of the PM2.5 mass (~ 52.1 %), with SO42−, NO3− and NH4+ as the major ions. On average, nitrate concentrations dominated over sulfate (mass ratio of 1.21), indicating influences from traffic emissions. OC and EC correlated well with each other and the highest OC / EC ratio (5.16) occurred in winter, suggesting complex OC sources likely including both secondarily formed and primarily emitted OA. Concentrations of eight trace elements (Mn, Zn, Al, B, Cr, Cu, Fe, Pb) can contribute up to 6.0 % of PM2.5 during winter. PAHs concentrations were also high in winter (140.25 ng m−3), which were predominated by median/high molecular weight PAHs with 5- and 6-rings. The organic matter including both water-soluble and water-insoluble species occupied ~ 20 % PM2.5 mass. SP-AMS determined that the WSOA had an average atomic oxygen-to-carbon (O / C), hydrogen-to-carbon (H / C), nitrogen-to-carbon (N / C) and organic matter-to-organic carbon (OM / OC) ratios of 0.36, 1.54, 0.11, and 1.74, respectively. Source apportionment of WSOA further identified two secondary OA (SOA) factors (a less oxidized and a more oxidized OA) and two primary OA (POA) factors (a nitrogen enriched hydrocarbon-like traffic OA and a cooking-related OA). On average, the POA contribution overweighed SOA (55 % vs. 45 %), indicating the important role of local anthropogenic emissions to the aerosol pollution in Changzhou. Our measurement also shows the abundance of organic nitrogen species in WSOA, and the source analyses suggest these species likely associated with traffic emissions, which warrants more investigations on PM samples from other locations.

scholarly journals Water-soluble organic carbon aerosols during a full New Delhi winter: Isotope-based source apportionment and optical properties

2014 ◽  
Vol 119 (6) ◽  
pp. 3476-3485 ◽  
Author(s):  
Elena N. Kirillova ◽  
August Andersson ◽  
Suresh Tiwari ◽  
Atul Kumar Srivastava ◽  
Deewan Singh Bisht ◽  
...  
Keyword(s):  
Optical Properties ◽  
Organic Carbon ◽  
Source Apportionment ◽  
Water Soluble ◽  
New Delhi ◽  
Water Soluble Organic Carbon ◽  
Soluble Organic Carbon ◽  
Carbon Aerosols

scholarly journals Characteristics, seasonality and sources of carbonaceous and ionic components in the tropical Indian aerosols

2011 ◽  
Vol 11 (2) ◽  
pp. 3937-3976 ◽  
Author(s):  
C. M. Pavuluri ◽  
K. Kawamura ◽  
S. G. Aggarwal ◽  
T. Swaminathan
Keyword(s):  
Organic Carbon ◽  
Atmospheric Aerosols ◽  
Atmospheric Transport ◽  
Indian Subcontinent ◽  
Ionic Species ◽  
Water Soluble ◽  
Carbonaceous Aerosols ◽  
Mass Fractions ◽  
High Concentrations ◽  
Ionic Components

Abstract. To better characterize South and Southeast Asian aerosols, PM10 samples collected from tropical Chennai, India (13.04° N; 80.17° E) were analyzed for carbonaceous and water-soluble ionic components. Concentration ranges of elemental carbon (EC) and organic carbon (OC) were 2.4–14 μg m−3 and 3.2–15.6 μg m−3 in winter samples whereas they were 1.1–2.5 μg m−3 and 4.1–17.6 μg m−3 in summer samples, respectively. Concentration of secondary organic carbon (SOC) retrieved from EC-tracer method was 4.6 ± 2.8 μg m−3 in winter and 4.3 ± 2.8 μg m−3 in summer. SO42- (8.8 ± 2.5 μg m−3 and 4.1 ± 2.7 μg m−3 in winter and summer, respectively) was found as the most abundant ionic species (57% on average, n = 49), followed by NH4+ (15%) > NO3− > Cl− > K+> Na+ > Ca2+ > MSA− > Mg2+. The mass fractions of EC, organic matter (OM) and ionic species varied seasonally, following the air mass trajectories and corresponding source strength. Based on mass concentration ratios of selected components and relations of EC and OC to marker species, we found that biofuel/biomass burning is the major source of atmospheric aerosols in South and Southeast Asia. The high concentrations of SOC and WSOC/OC ratios (ave. 0.45; n = 49) as well as good correlations between SOC and WSOC suggest that the secondary production of organic aerosols during long-range atmospheric transport is also significant in this region. This study provides the baseline data of carbonaceous aerosols for southern part of the Indian subcontinent.

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

2019 ◽  
Author(s):  
John G. Watson ◽  
Junji Cao ◽  
L.W. Antony Chen ◽  
Qiyuan Wang ◽  
Jie Tian ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Gas Phase ◽  
Flow Reactor ◽  
Combustion Efficiency ◽  
Emission Factors ◽  
Water Soluble ◽  
Atmospheric Aging ◽  
High Vapor ◽  
Southern Florida ◽  
Northern Alaska

Abstract. Peat fuels representing four biomes of boreal (western Russia and Siberia), temperate (northern Alaska, U.S.A.), subtropical (northern and southern Florida, U.S.A), 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] = 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 g kg−1 and 3‒10 g kg−1, respectively. EFs for nitrogen species are at the same magnitude of 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); as well as 2.4 ± 1.4 and 2.0 ± 0.7 g kg−1 for EFNOy (reactive nitrogen) and EFN2O (nitrous oxide). An oxidation flow reactor (OFR) was used to simulate atmospheric aging times of ~2 and ~7 days 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 ~15 % degradation after aging. Reductions of EFOC (~7‒9 g kg−1) after aging are most apparent for boreal peats with the largest degradation in organic carbon that evolves at <140 °C, indicating the loss of high vapor pressure semi-volatile 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) accounts 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 ~one- to two-thirds 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 % fuel N emitted as NH3 and 9.5 % of fuel N emitted as HCN. N2O and NOy constituted 5.7 % and 2.9 % of consumed fuel N. EFs from this study can be used to refine current emissions inventories.

scholarly journals Carbonaceous components, levoglucosan and inorganic ions in tropical aerosols from Tanzania, East Africa: implication for biomass burning contribution to organic aerosols

2012 ◽  
Vol 12 (11) ◽  
pp. 28661-28703 ◽  
Author(s):  
S. L. Mkoma ◽  
K. Kawamura ◽  
P. Fu
Keyword(s):  
Organic Carbon ◽  
East Africa ◽  
Biomass Burning ◽  
Inorganic Ions ◽  
Ionic Species ◽  
Water Soluble ◽  
Total Carbon ◽  
Rural Site ◽  
Wet Season ◽  
Pm2.5 And Pm10

Abstract. Atmospheric aerosol samples of PM2.5 and PM10 were collected at a rural site in Tanzania in 2011 during wet and dry seasons and they were analysed for carbonaceous components, levoglucosan and water-soluble inorganic ions. The mean mass concentrations of PM2.5 and PM10 were 28.2&amp;pm;6.4 μg m−3 and 47&amp;pm;8.2 μg m−3 in wet season, and 39.1&amp;pm;9.8 μg m−3 and 61.4&amp;pm;19.2 μg m−3 in dry season, respectively. Total carbon (TC) accounted for 16–19% of the PM2.5 mass and 13–15% of the PM10 mass. On average, 85.9 to 88.7% of TC in PM2.5 and 87.2 to 90.1% in PM10 was organic carbon (OC), of which 67–72% and 63% was found to be water-soluble organic carbon (WSOC) in PM2.5 and PM10, respectively. Water-soluble potassium (K+) and sulphate (SO42−) in PM2.5 and, sodium (Na+) and SO42− in PM10 were the dominant ionic species. We found, that concentrations of biomass burning tracers (levoglucosan and mannosan) well correlated with non-sea-salt-K+, WSOC and OC in the aerosols from Tanzania, East Africa. Mean contributions of levoglucosan to OC ranged between 3.9–4.2% for PM2.5 and 3.5–3.8% for PM10. This study demonstrates that emissions from biomass- and biofuel-burning activities followed by atmospheric photochemical processes mainly control the air quality in Tanzania.

Variation in carbonaceous and ionic species at a rural receptor location in the eastern Indo-Gangetic Plain

2021 ◽  
Author(s):  
Bijay Sharma ◽  
Anurag J. Polana ◽  
Jingying Mao ◽  
Shiguo Jia ◽  
Sayantan Sarkar
Keyword(s):  
Organic Carbon ◽  
Forest Fires ◽  
Ionic Species ◽  
Water Soluble ◽  
Photochemical Oxidation ◽  
Carbonaceous Aerosol ◽  
Charge Ratio ◽  
Gangetic Plain ◽  
Post Monsoon ◽  
Indo Gangetic Plain

&lt;p&gt;The Indo-Gangetic Plain (IGP) is one of the world&amp;#8217;s most populated river basins housing more than 700 million people. Apart from being a major source region of aerosols, the IGP is affected by transported aerosols from the Thar Desert, forest-fires and open burning of crop waste from central India. Studies have been carried out to understand the aerosol chemical composition and optical properties in source regions of IGP but knowledge is severely lacking for receptor locations viz. eastern IGP (eIGP). To address this, the present study reports the seasonal variability of carbonaceous and ionic species in ambient PM&lt;sub&gt;2.5&lt;/sub&gt; from a rural receptor location (Mohanpur, West Bengal) along with insights on aerosol acidity, its neutralization and potential source regimes. A total of 88 PM&lt;sub&gt;2.5&lt;/sub&gt; samples collected during the summer, post-monsoon and winter seasons of 2018 were analyzed for SO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt;, NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt;, Cl&lt;sup&gt;-&lt;/sup&gt;, Na&lt;sup&gt;+&lt;/sup&gt;, NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt;, K&lt;sup&gt;+&lt;/sup&gt;, Ca&lt;sup&gt;2+&lt;/sup&gt;, Mg&lt;sup&gt;2+&lt;/sup&gt;, F&lt;sup&gt;-&lt;/sup&gt;,&lt;sup&gt;&lt;/sup&gt;PO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;3-&lt;/sup&gt;, water-soluble organic carbon (WSOC), organic carbon (OC) and elemental carbon (EC) fractions. Sulfate, nitrate and ammonium (SNA) were the dominating ionic species throughout the seasons (67-86% out of the total ionic species measured). Significant positive Cl&lt;sup&gt;-&lt;/sup&gt; depletion in summer (49&amp;#177;20%) pointed towards influx of marine air while negative depletion in post-monsoon and winter suggested a biomass burning (BB) source, which was further supported by concentration-weighted trajectory analysis. Strong acidity was found to be highest during post-monsoon (141&amp;#177;76 nmol m&lt;sup&gt;-3&lt;/sup&gt;), followed by winter (117&amp;#177;36 nmol m&lt;sup&gt;-3&lt;/sup&gt;) and summer (40&amp;#177;14 nmol m&lt;sup&gt;-3&lt;/sup&gt;) with significant differences between summer and the other seasons. Neutralization factor (N&lt;sub&gt;f&lt;/sub&gt;) and equivalent charge ratio of cation to anion (R&lt;sub&gt;C/A&lt;/sub&gt;) revealed that summertime aerosols were neutral in nature while those of post-monsoon and winter were comparatively acidic with NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt; being the major neutralizing agent throughout the seasons. Correlations between WSOC and OC fractions (OC1, OC2, OC3 and OC4) suggested secondary formation of summertime WSOC (WSOC vs OC3: r=0.48, p&lt;0.05) via photochemical oxidation of volatile organic carbons (VOCs) while that of post-monsoon (WSOC vs OC1, OC2, OC3: r=0.45-0.62, &lt;em&gt;p&lt;/em&gt;&lt;0.05) and winter (WSOC vs OC1, OC2, OC3: r=0.58-0.68, &lt;em&gt;p&lt;/em&gt;&lt;0.05), both primary and secondary pathways seem important. To elucidate the role of BB, we looked into the two components of EC i.e., char-EC (EC1-PC) and soot-EC (EC2+EC3). The percent contribution of char-EC to EC was 65&amp;#177;17%, 90&amp;#177;10% and 98&amp;#177;1% during summer, post-monsoon and winter, respectively. Along with this, char-EC/soot-EC ratios of 2.3&amp;#177;1.8, 17.6&amp;#177;16.4 and 50.3&amp;#177;18.6 during summer, post-monsoon and winter, respectively, and significant correlations of the same with the BB-tracer K&lt;sup&gt;+&lt;/sup&gt; (post-monsoon: r=0.78, &lt;em&gt;p&lt;/em&gt;&lt;0.001; winter: r=0.64, &lt;em&gt;p&lt;/em&gt;&lt;0.01) indicated the importance of BB emissions in constraining carbonaceous aerosol profiles during post-monsoon and winter.&lt;/p&gt;

scholarly journals Source Apportionment of Aerosols by 14C Measurements in Different Carbonaceous Particle Fractions

Radiocarbon ◽  
2004 ◽  
Vol 46 (1) ◽  
pp. 475-484 ◽  
Author(s):  
S Szidat ◽  
T M Jenk ◽  
H W Gäggeler ◽  
H-A Synal ◽  
R Fisseha ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Source Apportionment ◽  
Atmospheric Aerosols ◽  
Elemental Carbon ◽  
Water Soluble ◽  
Total Carbon ◽  
Anthropogenic Sources ◽  
Ambient Aerosols ◽  
Carbonaceous Particle ◽  
Fossil Carbon

Radiocarbon enables a distinction between contemporary and fossil carbon, which can be used for the apportionment of biogenic and anthropogenic sources in environmental studies. In order to apply this approach to carbonaceous atmospheric aerosols, it is necessary to adapt pretreatment procedures to the requirements of 14C measurements. In this work, we followed an approach in which total carbon (TC) is subdivided into fractions of different chemical and physical properties. 14C data of ambient aerosols from Zürich (Switzerland) are presented for the 2 sub-fractions of TC, organic carbon (OC) and elemental carbon (EC). Furthermore, OC is separated into water-insoluble OC (WINSOC) and water-soluble OC (WSOC). Results demonstrate the importance to differentiate between these fractions for 14C-deduced source apportionment, as the contributions can range between both extremes, nearly exclusively biogenic and anthropogenic.

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