scholarly journals Year-round radiocarbon-based source apportionment of carbonaceous aerosols at two background sites in South Asia

2012 ◽  
Vol 117 (D10) ◽  
pp. n/a-n/a ◽  
Author(s):  
Rebecca J. Sheesley ◽  
Elena Kirillova ◽  
August Andersson ◽  
Martin Kruså ◽  
P. S. Praveen ◽  
...  
Keyword(s):  
South Asia ◽  
Source Apportionment ◽  
Carbonaceous Aerosols

scholarly journals Six-year source apportionment of submicron organic aerosols from near-continuous measurements at SIRTA (Paris area, France)

2019 ◽  
Author(s):  
Yunjiang Zhang ◽  
Olivier Favez ◽  
Jean-Eudes Petit ◽  
Francesco Canonaco ◽  
Francois Truong ◽  
...  
Keyword(s):  
Source Apportionment ◽  
Biomass Burning ◽  
Ambient Air ◽  
Carbonaceous Aerosols ◽  
Time Resolved ◽  
Pronounced Increase ◽  
Paris Area ◽  
Multi Wavelength ◽  
High Concentrations

Abstract. Organic aerosol (OA) particles are recognized as key factors influencing air quality and climate change. However, highly-time resolved year-round characterizations of their composition and sources in ambient air are still very limited due to challenging continuous observations. Here, we present an analysis of long-term variability of submicron OA using the combination of Aerosol Chemical Speciation Monitor (ACSM) and multi-wavelength aethalometer from November 2011 to March 2018 at a background site of the Paris region (France). Source apportionment of OA was achieved via partially constrained positive matrix factorization (PMF) using the multilinear engine (ME-2). Two primary OA (POA) and two oxygenated OA (OOA) factors were identified and quantified over the entire studied period. POA factors were designated as hydrocarbon-like OA (HOA) and biomass burning OA (BBOA). The latter factor presented a significant seasonality with higher concentrations in winter with significant monthly contributions to OA (18–33 %) due to enhanced residential wood burning emissions. HOA mainly originated from traffic emissions but was also influenced by biomass burning in cold periods. OOA factors were distinguished between their less- and more-oxidized fractions (LO-OOA and MO-OOA, respectively). These factors presented distinct seasonal patterns, associated with different atmospheric formation pathways. A pronounced increase of LO-OOA concentrations and contributions (50–66 %) was observed in summer, which may be mainly explained by secondary OA (SOA) formation processes involving biogenic gaseous precursors. Conversely high concentrations and OA contributions (32–62 %) of MO-OOA during winter and spring seasons were partly associated with anthropogenic emissions and/or long-range transport from northeastern Europe. The contribution of the different OA factors as a function of OA mass loading highlighted the dominant roles of POA during pollution episodes in fall and winter, and of SOA for highest springtime and summertime OA concentrations. Finally, long-term trend analyses indicated a decreasing feature (of about 200 ng m−3 yr−1) for MO-OOA, very limited or insignificant decreasing trends for primary anthropogenic carbonaceous aerosols (BBOA and HOA, along with the fossil fuel and biomass burning black carbon components), and no trend for LO-OOA over the 6+-year investigated period.

scholarly journals Six-year source apportionment of submicron organic aerosols from near-continuous highly time-resolved measurements at SIRTA (Paris area, France)

2019 ◽  
Vol 19 (23) ◽  
pp. 14755-14776 ◽  
Author(s):  
Yunjiang Zhang ◽  
Olivier Favez ◽  
Jean-Eudes Petit ◽  
Francesco Canonaco ◽  
Francois Truong ◽  
...  
Keyword(s):  
Source Apportionment ◽  
Biomass Burning ◽  
Ambient Air ◽  
Carbonaceous Aerosols ◽  
Time Resolved ◽  
Pronounced Increase ◽  
Paris Area ◽  
Range Transport ◽  
High Concentrations

Abstract. Organic aerosol (OA) particles are recognized as key factors influencing air quality and climate change. However, highly time-resolved long-term characterizations of their composition and sources in ambient air are still very limited due to challenging continuous observations. Here, we present an analysis of long-term variability of submicron OA using the combination of an aerosol chemical speciation monitor (ACSM) and a multiwavelength Aethalometer from November 2011 to March 2018 at a peri-urban background site of the Paris region (France). Source apportionment of OA was achieved via partially constrained positive matrix factorization (PMF) using the multilinear engine (ME-2). Two primary OA (POA) and two oxygenated OA (OOA) factors were identified and quantified over the entire studied period. POA factors were designated as hydrocarbon-like OA (HOA) and biomass burning OA (BBOA). The latter factor presented a significant seasonality with higher concentrations in winter with significant monthly contributions to OA (18 %–33 %) due to enhanced residential wood burning emissions. HOA mainly originated from traffic emissions but was also influenced by biomass burning in cold periods. OOA factors were distinguished between their less- and more-oxidized fractions (LO-OOA and MO-OOA, respectively). These factors presented distinct seasonal patterns, associated with different atmospheric formation pathways. A pronounced increase in LO-OOA concentrations and contributions (50 %–66 %) was observed in summer, which may be mainly explained by secondary OA (SOA) formation processes involving biogenic gaseous precursors. Conversely, high concentrations and OA contributions (32 %–62 %) of MO-OOA during winter and spring seasons were partly associated with anthropogenic emissions and/or long-range transport from northeastern Europe. The contribution of the different OA factors as a function of OA mass loading highlighted the dominant roles of POA during pollution episodes in fall and winter and of SOA for highest springtime and summertime OA concentrations. Finally, long-term trend analyses indicated a decreasing feature (of about −175 ng m−3 yr−1) for MO-OOA, very limited or insignificant decreasing trends for primary anthropogenic carbonaceous aerosols (BBOA and HOA, along with the fossil-fuel and biomass-burning black carbon components) and no statistically significant trend for LO-OOA over the 6-year investigated period.

scholarly journals Non methane hydrocarbon (NMHC) fingerprints of major urban and agricultural emission sources active in South Asia for use in source apportionment studies

2020 ◽  
Author(s):  
Ashish Kumar ◽  
Vinayak Sinha ◽  
Muhammed Shabin ◽  
Haseeb Hakkim ◽  
Bernard Bonsang ◽  
...  
Keyword(s):  
South Asia ◽  
Source Apportionment ◽  
Ambient Air ◽  
Exhaust Emissions ◽  
Emission Sources ◽  
Formation Potential ◽  
Fire Emissions ◽  
Chemical Tracers ◽  
Evaporative Emissions ◽  
Vehicular Exhaust

Abstract. In complex atmospheric emission environments such as urban agglomerates, multiple sources control the ambient chemical composition driving air quality and regional climate. In contrast to pristine sites, where reliance on single or few chemical tracers is often adequate to resolve pollution plumes and source influences, comprehensive chemical fingerprinting of sources using non-methane hydrocarbons and identification of suitable tracer molecule/molecules and emission ratios is necessary. Here, we characterize and present chemical fingerprints of some major urban and agricultural emission sources active in South Asia such as paddy stubble burning, garbage burning, idling vehicular exhaust and evaporative fuel emissions. Whole air samples were collected actively from the emission sources in passivated air sampling steel canisters and then analyzed for 49 NMHCs (22 alkanes, 16 aromatics, 10 alkene and 1 alkyne) using thermal desorption gas chromatography flame ionisation detection (TD-GC-FID). Based on the measured source profiles, chemical tracers were identified for distinguishing varied emission sources and also for use in PMF source apportionment models. Thus, we were able to identify chemical tracers such as i-pentane for petrol vehicular exhaust and evaporative emissions, propane for LPG evaporative and LPG vehicular exhaust emissions, and acetylene for the biomass fires during the flaming stage. Furthermore, we observed propane to be a major NMHC emission (8 %) from paddy stubble fires and therefore in an emission environment impacted by crop residue fires, use of propane as a fugitive LPG emission tracer requires caution. Isoprene was identified as a potential tracer for distinguishing paddy stubble and garbage burning in the absence of isoprene emissions at night from biogenic sources. Diesel vehicular exhaust comprised of > 50 % alkenes and alkyne by mass composition while diesel evaporative emissions were enriched in C5–C8 alkanes and aromatics. The secondary pollutant formation potential and human health impact of the sources was also assessed in terms of their OH reactivity (s−1), ozone formation potential (OFP, gO3/gNMHC) and fractional BTEX content. Petrol vehicular exhaust emissions, paddy stubble fires and garbage fires were identified as the most polluting among the sources studied in this work. Source specific inter-NMHC molar ratios which are often employed for identifying ambient air pollution emission plumes and assessing photochemical ageing were also examined. Toluene / benzene (T / B) ratios were a good tracer for distinguishing the paddy stubble fire emissions in flaming (0.42) and smoldering stages (1.39), garbage burning emissions (0.21–0.32) and traffic emissions (3.54). While i-butane / n-butane ratios were found to be similar (0.20–0.30) for many sources, i-pentane / n-pentane ratios were useful for distinguishing biomass burning emissions (0.09–0.70) from the traffic/fossil fuel emissions (1.55–8.77). The results of this study provide a new foundational framework for quantitative source apportionment studies in complex emission environments such as South Asia.

scholarly journals Accuracy and precision of <sup>14</sup>C-based source apportionment of organic and elemental carbon in aerosols using the Swiss_4S protocol

2015 ◽  
Vol 8 (4) ◽  
pp. 3933-3965 ◽  
Author(s):  
G. O. Mouteva ◽  
S. M. Fahrni ◽  
G. M. Santos ◽  
J. T. Randerson ◽  
Y. L. Zhang ◽  
...  
Keyword(s):  
Source Apportionment ◽  
Elemental Carbon ◽  
Small Sample ◽  
Mitigation Strategies ◽  
Pure Oxygen ◽  
Carbonaceous Aerosols ◽  
Carbon Fraction ◽  
Fossil Carbon ◽  
Vacuum Line ◽  
Set Up

Abstract. Aerosol source apportionment remains a critical challenge for understanding the transport and aging of aerosols, as well as for developing successful air pollution mitigation strategies. The contributions of fossil and non-fossil sources to organic carbon (OC) and elemental carbon (EC) in carbonaceous aerosols can be quantified by measuring the radiocarbon (14C) content of each carbon fraction. However, the use of 14C in studying OC and EC has been limited by technical challenges related to the physical separation of the two fractions and small sample sizes. There is no common procedure for OC/EC 14C analysis, and uncertainty studies have largely focused on the precision of yields. Here, we quantified the uncertainty in 14C measurement of aerosols associated with the isolation and analysis of each carbon fraction with the Swiss_4S thermal-optical analysis (TOA) protocol. We used an OC/EC analyzer (Sunset Laboratory Inc., OR, USA) coupled to vacuum line to separate the two components. Each fraction was thermally desorbed and converted to carbon dioxide (CO2) in pure oxygen (O2). On average 91% of the evolving CO2 was then cryogenically trapped on the vacuum line, reduced to filamentous graphite, and measured for its 14C content via accelerator mass spectrometry (AMS). To test the accuracy of our set-up, we quantified the total amount of extraneous carbon introduced during the TOA sample processing and graphitization as the sum of modern and fossil (14C-depleted) carbon introduced during the analysis of fossil reference materials (adipic acid for OC and coal for EC) and contemporary standards (oxalic acid for OC and rice char for EC) as a function of sample size. We further tested our methodology by analyzing five ambient airborne particulate matter (PM2.5) samples with a range of OC and EC concentrations and 14C contents in an interlaboratory comparison. The total modern and fossil carbon blanks of our set-up were 0.8 ± 0.4 and 0.67 ± 0.34 μg C, respectively, based on multiple measurements of ultra-small samples. The Swiss_4S protocol and the cryo-trapping contributed 0.37 ± 0.18 μg of modern carbon and 0.13 ± 0.07 μg of fossil carbon to the estimated blanks, with consistent estimates obtained for the two laboratories. There was no difference in the background correction between the OC and EC fractions. Our set-up allowed us to efficiently isolate and trap each carbon fraction with the Swiss_4S protocol and to perform 14C analysis of ultra-small OC and EC samples with high accuracy and low 14C blanks.

scholarly journals Source apportionment of carbonaceous aerosols in Beijing with radiocarbon and organic tracers: insight into the differences between urban and rural sites

2021 ◽  
Vol 21 (10) ◽  
pp. 8273-8292
Author(s):  
Siqi Hou ◽  
Di Liu ◽  
Jingsha Xu ◽  
Tuan V. Vu ◽  
Xuefang Wu ◽  
...  
Keyword(s):  
Source Apportionment ◽  
Biomass Burning ◽  
Fine Particles ◽  
Water Soluble ◽  
Carbonaceous Aerosol ◽  
Balance Model ◽  
Gas Chromatography Mass Spectrometry ◽  
Urban Site ◽  
Carbonaceous Aerosols ◽  
Carbonaceous Particles

Abstract. Carbonaceous aerosol is a dominant component of fine particles in Beijing. However, it is challenging to apportion its sources. Here, we applied a newly developed method which combined radiocarbon (14C) with organic tracers to apportion the sources of fine carbonaceous particles at an urban (IAP) and a rural (PG) site of Beijing. PM2.5 filter samples (24 h) were collected at both sites from 10 November to 11 December 2016 and from 22 May to 24 June 2017. 14C was determined in 25 aerosol samples (13 at IAP and 12 at PG) representing low pollution to haze conditions. Biomass burning tracers (levoglucosan, mannosan, and galactosan) in the samples were also determined using gas chromatography–mass spectrometry (GC-MS). Higher contributions of fossil-derived OC (OCf) were found at the urban site. The OCf / OC ratio decreased in the summer samples (IAP: 67.8 ± 4.0 % in winter and 54.2 ± 11.7 % in summer; PG: 59.3 ± 5.7 % in winter and 50.0 ± 9.0 % in summer) due to less consumption of coal in the warm season. A novel extended Gelencsér (EG) method incorporating the 14C and organic tracer data was developed to estimate the fossil and non-fossil sources of primary and secondary OC (POC and SOC). It showed that fossil-derived POC was the largest contributor to OC (35.8 ± 10.5 % and 34.1 ± 8.7 % in wintertime for IAP and PG, 28.9 ± 7.4 % and 29.1 ± 9.4 % in summer), regardless of season. SOC contributed 50.0 ± 12.3 % and 47.2 ± 15.5 % at IAP and 42.0 ± 11.7 % and 43.0 ± 13.4 % at PG in the winter and summer sampling periods, respectively, within which the fossil-derived SOC was predominant and contributed more in winter. The non-fossil fractions of SOC increased in summer due to a larger biogenic component. Concentrations of biomass burning OC (OCbb) are resolved by the extended Gelencsér method, with average contributions (to total OC) of 10.6 ± 1.7 % and 10.4 ± 1.5 % in winter at IAP and PG and 6.5 ± 5.2 % and 17.9 ± 3.5 % in summer, respectively. Correlations of water-insoluble OC (WINSOC) and water-soluble OC (WSOC) with POC and SOC showed that although WINSOC was the major contributor to POC, a non-negligible fraction of WINSOC was found in SOC for both fossil and non-fossil sources, especially during winter. In summer, a greater proportion of WSOC from non-fossil sources was found in SOC. Comparisons of the source apportionment results with those obtained from a chemical mass balance model were generally good, except for the cooking aerosol.

scholarly journals Fossil versus contemporary sources of fine elemental and organic carbonaceous particulate matter during the DAURE campaign in Northeast Spain

2011 ◽  
Vol 11 (8) ◽  
pp. 23573-23618 ◽  
Author(s):  
M. C. Minguillón ◽  
N. Perron ◽  
X. Querol ◽  
S. Szidat ◽  
S. M. Fahrni ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Organic Carbon ◽  
Source Apportionment ◽  
Biomass Burning ◽  
Atmospheric Aerosols ◽  
Fine Particulate Matter ◽  
Western Mediterranean ◽  
Carbonaceous Aerosol ◽  
Carbonaceous Aerosols ◽  
Background Site

Abstract. We present results from the international field campaign DAURE (Determination of the sources of atmospheric Aerosols in Urban and Rural Environments in the western Mediterranean), with the objective of apportioning the sources of fine carbonaceous aerosols. Submicron fine particulate matter (PM1) samples were collected during February-March 2009 and July 2009 at an urban background site in Barcelona (BCN) and at a forested regional background site in Montseny (MSY). We present radiocarbon (14C) analysis for elemental and organic carbon (EC and OC) and source apportionment for these data. We combine the results with those from component analysis of aerosol mass spectrometer (AMS) measurements, and compare to levoglucosan-based estimates of biomass burning OC, source apportionment of filter data with inorganic+EC+OC speciation, submicron bulk potassium (K) concentrations, and gaseous acetonitrile concentrations. At BCN, 87 % and 91 % of the EC on average, in winter and summer, respectively, had a fossil origin, whereas at MSY these fractions were 66 % and 79 %. The contribution of fossil sources to organic carbon (OC) at BCN was 40 % and 48 %, in winter and summer, respectively, and 31 % and 25 % at MSY. The combination of results obtained using the 14C technique, AMS data, and the correlations between fossil OC and fossil EC imply that the fossil OC at Barcelona is ~65 % primary whereas at MSY the fossil OC is mainly secondary (~85 %). Day-to-day variation in total carbonaceous aerosol loading and the relative contributions of different sources predominantly depended on the meteorological transport conditions. The estimated biogenic secondary OC at MSY only increased by ~40 % compared to the order-of-magnitude increase observed for biogenic volatile organic compounds (VOCs) between winter and summer, which highlights the uncertainties in the estimation of that component. Biomass burning contributions estimated using the 14C technique ranged from similar to higher than when estimated using other techniques, and the different estimations were highly or moderately correlated. Differences can be explained by the contribution of secondary organic matter (not included in the primary biomass burning source estimates), and/or by an overestimation of the biomass burning OC contribution by the 14C technique if the estimated biomass burning EC/OC ratio used for the calculations is too high for this region. Acetonitrile concentrations correlate well with the biomass burning EC determined by 14C. K is a noisy tracer for biomass burning.

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