Source Apportionment Of Carbonaceous Aerosols Research Articles

Source Apportionment of Carbonaceous Aerosols during PM2.5 Pollution Episodes in Xi’an, Northwestern China: Estimation of the Potential of Carbon Emission Reduction by Rural Household Energy Substitution

Source Apportionment of Carbonaceous Aerosols during PM2.5 Pollution Episodes in Xi’an, Northwestern China: Estimation of the Potential of Carbon Emission Reduction by Rural Household Energy Substitution

Composition and sources of carbonaceous aerosol in the European Arctic at Zeppelin Observatory, Svalbard (2017 to 2020)

Abstract. We analyzed long-term measurements of organic carbon, elemental carbon, and source-specific organic tracers from 2017 to 2020 to constrain carbonaceous aerosol sources in the rapidly changing Arctic. Additionally, we used absorption photometer (Aethalometer) measurements to constrain equivalent black carbon (eBC) from biomass burning and fossil fuel combustion, using positive matrix factorization (PMF). Our analysis shows that organic tracers are essential for understanding Arctic carbonaceous aerosol sources. Throughout 2017 to 2020, levoglucosan exhibited bimodal seasonality, reflecting emissions from residential wood combustion (RWC) in the heating season (November to May) and from wildfires (WFs) in the non-heating season (June to October), demonstrating a pronounced interannual variability in the influence of WF. Biogenic secondary organic aerosol (BSOA) species (2-methyltetrols) from isoprene oxidation was only present in the non-heating season, peaking in July to August. Warm air masses from Siberia led to a substantial increase in 2-methyltetrols in 2019 and 2020 compared to 2017 to 2018. This highlights the need to investigate the contribution of local sources vs. long-range atmospheric transport (LRT), considering the temperature sensitivity of biogenic volatile organic compound emissions from Arctic vegetation. Tracers of primary biological aerosol particles (PBAPs), including various sugars and sugar alcohols, showed elevated levels in the non-heating season, although with different seasonal trends, whereas cellulose had no apparent seasonality. Most PBAP tracers and 2-methyltetrols peaked during influence of WF emissions, highlighting the importance of measuring a range of source-specific tracers to understand sources and dynamics of carbonaceous aerosol. The seasonality of carbonaceous aerosol was strongly influenced by LRT episodes, as background levels are extremely low. In the non-heating season, the organic aerosol peak was as influenced by LRT, as was elemental carbon during the Arctic haze period. Source apportionment of carbonaceous aerosol by Latin hypercube sampling showed mixed contributions from RWC (46 %), fossil fuel (FF) sources (27 %), and BSOA (25 %) in the heating season. In contrast, the non-heating season was dominated by BSOA (56 %), with lower contributions from WF (26 %) and FF sources (15 %). Source apportionment of eBC by PMF showed that FF combustion dominated eBC (70±2.7 %), whereas RWC (22±2.7 %) was more abundant than WF (8.0±2.9 %). Modeled BC concentrations from FLEXPART (FLEXible PARTicle dispersion model) attributed an almost equal share to FF sources (51±3.1 %) and to biomass burning. Both FLEXPART and the PMF analysis concluded that RWC is a more important source of (e)BC than WF. However, with a modeled RWC contribution of 30±4.1 % and WF of 19±2.8 %, FLEXPART suggests relatively higher contributions to eBC from these sources. Notably, the BB fraction of EC was twice as high as that of eBC, reflecting methodological differences between source apportionment by LHS and PMF. However, important conclusions drawn are unaffected, as both methods indicate the presence of RWC- and WF-sourced BC at Zeppelin, with a higher relative BB contribution during the non-heating season. In summary, organic aerosol (281±106 ng m−3) constitutes a significant fraction of Arctic PM10, although surpassed by sea salt aerosol (682±46.9 ng m−3), mineral dust (613±368 ng m−3), and typically non-sea-salt sulfate SO42- (314±62.6 ng m−3), originating mainly from anthropogenic sources in winter and from natural sources in summer.

Sources of atmospheric light-absorbing fine aerosols: Insights from optical source apportionment utilizing measurements made during COVID-19 lockdowns at a COALESCE network site - Bhopal, India

The source-related optical characteristics of carbonaceous aerosols which absorb light are not well-known as they can be generated by a variety of sources. In this study, specific source-related optical properties of carbonaceous aerosols and mineral dust were investigated using a two-year dataset of absorption at multiple wavelengths and chemical species measured at Bhopal, India. A receptor model (Positive Matrix Factorization PMF5) was applied to the combined dataset to achieve optical source apportionment of carbonaceous aerosols and mineral dust. PMF resolved six factors accounting for carbonaceous aerosols and dust particulate matter (CDPM), which were identified as coal combustion, traffic exhaust, biomass burning, mineral dust, industry, and secondary organic aerosol (SOA) factors. The average contributions of these factors to the total CDPM mass were 29 % (coal combustion), 20 % (SOA), 16 % (traffic exhaust), 15 % (industry), 14 % (biomass burning), and 6 % (mineral dust (MD)) during the study period. The dominant contributors (at 405 nm) to aerosol light absorption were coal combustion (33 %), traffic exhaust (30 %), and biomass burning (29 %) factors. Specific source-related absorption Ångström exponent (AAE) values indicated that black carbon (BC) was the dominant light absorber in the coal and traffic emission factors. However, brown carbon (BrC) was present in the biomass-burning emissions. The specific source-related mass absorption cross section (MAC) for BC from coal combustion was higher at 635 nm than for MACBC from biomass burning, industry, and traffic exhaust factors. Overall, this study helped in the identification of additional light-absorbing sources of CDPM such as MD and SOA, and differentiate between optical parameters (AAE and MAC) of light-absorbing species in these sources.

Characteristics and Source Apportionment of Carbonaceous Aerosols in the Typical Urban Areas in Chongqing During Winter

To investigate the characteristics, source apportionment, and potential source areas of carbonaceous aerosols in Chongqing during winter, PM2.5 samples were collected from January 2021 to February 2021 in the urban areas of Wanzhou (WZ), Yubei (YB), and Shuangqiao (SQ). The results showed that the average mass concentrations of PM2.5, OC, and EC in SQ were (72.6 ±33.3), (18.2 ±8.2), and (4.4 ±1.7) μg·m-3, respectively, higher than those in WZ[(67.2 ±30.3), (17.2 ±7.4), and (5.1 ±2.4) μg·m-3] and YB[(63.4 ±25.7), (15.4 ±6.3), and (4.2 ±1.9) μg·m-3]. Compared with that during the clear period, the concentration and fraction of EC in total carbon increased by 103.0% and 8.1%, respectively, in WZ compared to that in other areas during pollution period, whereas the OC/EC ratio was decreased significantly (-10.5%), indicating that the primary emission of carbonaceous aerosols increased significantly during the pollution period. The average mass concentrations of secondary organic carbon (SOC) in SQ and YB were (7.7 ±4.8) μg·m-3 and (6.9 ±2.8) μg·m-3 significantly higher, respectively, than that in WZ[(4.5 ±1.9) μg·m-3] during the campaign. This indicated that the secondary transformation had a greater influence on the carbonaceous aerosols in SQ and YB than that in WZ. Furthermore, in contrast to that in WZ, the ratios of SOC/OC were increased with the increase in PM2.5 concentrations, and significant correlations between SOC concentration and aerosol water content, NO2 concentration, and the value of NOR were observed in SQ and YB (P < 0.01), indicating that the increasing of carbonaceous aerosol concentrations might be mainly driven by the SOC with -NO2 groups produced by aqueous chemical reactions during winter in SQ and YB. The positive definite matrix factor (PMF) results in these urban areas showed that the contribution of biomass/coal combustion source in WZ (47.4%) was significantly higher than that in YB (34.2%) and SQ (38.1%), whereas the gasoline motor vehicle emission and secondary transformation impacts were more significant in YB. The results of the concentration weighted trajectory (CWT) showed that the potential sources of carbonaceous aerosols were mainly the local and northeastern parts of these urban areas (such as Changshou).

Seasonal Trends and source Apportionment of Carbonaceous Aerosols in PM10 at Central Delhi, India

Seasonal Trends and source Apportionment of Carbonaceous Aerosols in PM10 at Central Delhi, India

Emission Characteristics of Organic Carbon and Elemental Carbon in PM10 and PM2.5 from Vehicle Exhaust and Civil Combustion Fuels

To study the emission characteristics of carbonaceous aerosol in particulate matter emitted from vehicle exhaust and main civil combustion fuels, organic carbon (OC) and elemental carbon (EC) in PM10 and PM2.5 samples from vehicle sources (gasoline vehicles, light duty diesel vehicles, and heavy duty diesel vehicles), civil coal (chunk coal and briquette coal), and biomass fuels (wheat straw, wood plank, and grape branches) were collected and analyzed by using a multifunctional portable dilution channel sampler and the Model 5L-NDIR OC/EC analyzer. The results showed that there were significant differences in the proportion of carbonaceous aerosols in PM10 and PM2.5from different emission sources. The proportions of total carbon (TC) in PM10 and PM2.5 of different emission sources were 40.8%-68.5% and 30.5%-70.9%, respectively, and the OC/EC were 1.49-31.56 and 1.90-87.57, respectively. The carbon components produced by different emission sources were dominated by OC, and the OC/TC values in PM10 and PM2.5 were 56.3%-97.0% and 65.0%-98.7%, respectively. The proportions of OC in carbonaceous aerosols in PM10and PM2.5 were in the descending order of:briquette coal>chunk coal>gasoline vehicle>wood plank>wheat straw>light duty diesel vehicle>heavy duty diesel vehicle and briquette coal>gasoline car>grape branches>chunk coal>light duty diesel vehicle>heavy duty diesel vehicle, respectively. The main components of carbonaceous aerosols in PM10 and PM2.5 emitted from the various emission sources were different, and source apportionment of carbonaceous aerosols could be accurately distinguished by their ingredient composition profiles.

Is biomass burning always a dominant contributor of fine aerosols in upper northern Thailand?

Biomass burning (BB) is an important contributor to the air pollution in Southeast Asia (SEA), but the emission sources remain great uncertainty. In this study, PM2.5 samples were collected from an urban (Chiang Mai University, CMU) and a rural (Nong Tao village, NT) site in Chiang Mai, Thailand from February to April (high BB season, HBB) and from June to September (low BB season, LBB) in 2018. Source apportionment of carbonaceous aerosols was carried out by Latin Hypercube Sampling (LHS) method incorporating the radiocarbon (14C) and organic markers (e.g., dehydrated sugars, aromatic acids, etc.). Thereby, carbonaceous aerosols were divided into the fossil-derived elemental carbon (ECf), BB-derived EC (ECbb), fossil-derived primary and secondary organic carbon (POCf, SOCf), BB-derived OC (OCbb) and the remaining OC (OCnf, other). The fractions of ECbb generally prevailed over ECf throughout the year. OCbb was the dominant contributor to total carbon with a clear seasonal trend (65.5±5.8% at CMU and 79.9±7.6% at NT in HBB, and 39.1±7.9% and 42.8±4.6% in LBB). The distribution of POCf showed a spatial difference with a higher contribution at CMU, while SOCf displayed a temporal variation with a greater fraction in LBB. OCnf, other was originated from biogenic secondary aerosols, cooking emissions and bioaerosols as resolved by the principal component analysis with multiple liner regression model. The OCnf, other contributed within a narrow range of 6.6%-14.4%, despite 34.9±7.9% at NT in LBB. Our results highlight the dominance of BB-derived fractions in carbonaceous aerosols in HBB, and call the attention to the higher production of SOC in LBB.

Carbonaceous aerosols in Lvliang, China: seasonal variation, spatial distribution and source apportionment

Environmental context Lvliang, one of the main cities on the Fenwei Plain, is a key atmospheric pollution prevention area in China. Identification of sources of aerosols is essential to improving environmental air quality in this region. The quantitative source apportionment of carbonaceous aerosols performed in this study provides a better understanding of their sources and implications for climate and air-quality management policies in the Fenwei plain. Rationale Organic carbon (OC) and elemental carbon (EC) are major components of fine particulate matter (PM2.5), and they are of concern due to their significant impacts on human health and climate. Methodology PM2.5 samples were collected daily during four consecutive seasons from 2018 to 2019. This paper highlights the seasonal variations, sources and transport characteristics of carbonaceous aerosol in Lvliang, China. Results The OC and EC concentrations exhibited strong seasonal variations, with the highest in winter, mainly due to high pollution caused by winter heating in northern cities, and secondary OC (SOC) contribution. The average OC/EC ratio (1.72) in Lvliang was lower than those in most regions in China, further indicating that this region was greatly affected by primary source emissions. The highest SOC/OC ratio in summer (25.3%) was due to the positive correlation between SOC and temperature. Through the positive matrix factorisation (PMF) model, four sources of carbonaceous aerosols were identified: vehicle emissions (31.26%), coal combustion (30.83%), biomass combustion (24.36%) and dust emissions (13.55%). Potential source contribution function (PSCF) results indicated that in addition to the impact of local emissions, coal emissions from Ningxia and Shaanxi, motor vehicle emissions and biomass from Inner Mongolia and Ningxia and dust from Shaanxi and Henan Provinces were the major contributors to pollution. Discussion These data provide key information for formulating emission reduction policies and improving air quality on the Fenwei Plain and highlights the urgent need for inter-regional prevention and control measures for the cities in Lvliang.

A year-long study on PM2.5 and its carbonaceous components over eastern Himalaya in India: Contributions of local and transported fossil fuel and biomass burning during premonsoon

A year-long (March 2019–February 2020) study on the characterization of fine mode carbonaceous aerosols has been conducted over a high altitude urban atmosphere, Darjeeling (27.01°N, 88.15°E, 2200 m asl) in eastern Himalaya. The fine mode aerosol (PM2.5; 41.7 ± 23.7 μgm−3), total carbonaceous aerosols (TCA; 19.8 ± 7.7 μgm−3), organic carbon (OC; 8.0 ± 3.9 μgm−3) and elemental carbon (EC; 2.0 ± 0.9 μgm−3) exhibited similar seasonal variability with the highest abundance during winter followed by premonsoon, postmonsoon and minimum in monsoon. The OC:EC varied over a range of 2.8–19.4 whereas the secondary organic carbon ranged between 1.9 and 17.1 μgm−3 respectively. Higher PM2.5 associated with higher winds and elevated mixing layer depth suggest a strong influence of regional and long-range transport. In addition to the usual morning and evening rush-hour peaks, the impact of low land plain regions driven by up-slope valley winds was observed for the carbonaceous components. A novel approach has been taken to find out the individual contributions from the local and transported fossil fuel, biomass burning, and biogenic sources to OC and EC during premonsoon. We observed that the local fossil fuel (43%) contributions dominated over the biomass burning (39%) for EC whereas the contributions of local biomass burning and the local fossil fuel were same (46%) for OC. EC exhibited a higher contribution (18%) from the regional/long-range transport compared to OC (8%). IGP and Nepal were found to be the maximum contributing long distant source regions for the carbonaceous aerosol loading over eastern Himalaya. Such individual source apportionment of carbonaceous aerosols over eastern Himalaya makes the study unique and first-ever of its kind and immensely helpful for building robust mitigation action plans.

Carbonaceous aerosol source apportionment and assessment of transport-related pollution

Diesel vehicles are one of many sources of black carbon (BC) emissions in Europe; nevertheless, due to recent changes in fuel composition towards renewable fuel such as biodiesel, advances in engine design and pollution control technology, BC and organic carbon (OC) emissions may worsen air quality and encourage global warming. As there are no regulatory terms on BC mass concentration levels, assessment of pollution sources is crucial for air quality improvement policies and mitigation of climate change. BC mass concentration and aerosol optical absorption were derived using 7-wavelenght Aethalometer during 3 measurement campaigns in 2014, 2017, and 2020. BC source apportionment analysis was performed using 18 combinations of absorption Ångström exponent (AAE) values for assessing BC to fossil fuel combustion and biomass burning. The choice of the most suitable AAE combination (0.9 and 2.2, respectively) was supported by organic aerosol (OA) source apportionment results. AAE value for transport exhaust emission (0.95) from locally available diesel fuel was established using (CI) 1.9 TDI engine with different engine torque regimes and 7-wavelenght Aethalometer. Statistically and experimentally obtained values were compared and showed great agreement. Subsequently, a statistically obtained AAEtr value was used for BC source apportionment and long-term analysis. A significant increase in the contribution of transport-related BC contribution was observed between years 2014 and 2020 (from 51% to 65%) which was associated with a boost in the use of diesel vehicles (by 83.9% of diesel passenger cars comparing 2014 and 2020) and growing diesel fuel consumption. These findings underline the diesel transport-induced problem for local air quality together with its impact on atmospheric radiative balance and raise concerns for public health.

Source apportionment of carbonaceous aerosols using hourly data and implications for reducing PM2.5 in the Pearl River Delta region of South China

Ambient fine particulate matter (PM2.5) levels in South China have been decreasing in the past decade, but the decreasing rates differed between its major chemical components, e.g., with much small rates for carbonaceous aerosols than for secondary inorganic aerosols. To investigate the sources of carbonaceous aerosols in this region, a comprehensive campaign was carried out in urban Guangzhou in the winter of 2019–2020 using a combination of various instruments. Data generated from this campaign include hourly total carbon (TC), black carbon (BC), criteria air pollutants and meteorological parameters, 4-hourly particle-bound elements, and chemically-resolved daily PM2.5. Similar diurnal patterns were observed for TC, CO and NO2, suggesting TC was very likely related to vehicle exhaust emission. Secondary organic carbon (SOC) estimated using the Minimum R squared (MRS) method accounted for 35 ± 17% of OC, indicating strong atmospheric oxidation capacity. Four major source factors for carbonaceous aerosols were identified by positive matrix factorization (PMF) model, including coal combustion, traffic emissions, soil dust and ship emissions, which accounted for 37 ± 23%, 39 ± 23%, 14 ± 10% and 10 ± 13%, respectively, of TC mass concentration, 38 ± 24%, 38 ± 23%, 14 ± 10% and 10 ± 12%, respectively, of OC mass concentration, and 29 ± 21%, 43 ± 22%, 14 ± 11% and 14 ± 15%, respectively, of EC mass concentration. Among these sources, traffic emission was the most important one, suggesting the necessity for promoting clean energy vehicles and relieving urban traffic congestion.

Seasonal observation and source apportionment of carbonaceous aerosol from forested rural site (Lithuania)

In this work, we conducted a study of the stable carbon isotope ratios of total carbon (δ13CTC) for submicron aerosol particles (<1 μm) that were collected year round (2014) at a hemiboreal forest site in Lithuania. Higher δ13CTC values characterised the seasonal variation in δ13CTC during the cold season (average −26.9 ± 0.7‰) with lower values observed during the warm season (−27.6 ± 0.6‰). The total carbon (TC) concentration was below 8 μg/m3 during the one-year measurement period. There was one pollution event in autumn when concentrations reached up to 14.8 μg/m3. In addition to the offline analysis of the filter samples, the online measurements of aerosol physical and chemical properties were conducted from 15 May to September 27, 2014 by operating the Aethalometer AE-31 and a quadrupole-type Aerosol Chemical Speciation Monitor (ACSM). Source apportionment was conducted by analysing the ACSM mass spectra using Positive Matrix Factorisation (PMF). Three main factors were derived, pointing to primary emissions from biomass burning along with the secondary formation of less and more oxygenated organic aerosol of biogenic origin. A comparative analysis of δ13CTC with organic carbon (OC), elemental carbon (EC), and organic markers justified two dominant sources (biomass burning and fossil fuel combustion) of aerosol particles at the hemiboreal forest site during the cold season.

Source apportionment of carbonaceous aerosols in diverse atmospheric environments of China by dual-carbon isotope method

Carbonaceous aerosols are major components in PM2.5 of both polluted and clean atmosphere. Accurate source apportionment of carbonaceous aerosols may support effective PM2.5 control. Dual-carbon isotope method (14C and 13C) was adopted to identify the contribution of three main air pollution sources biogenic and biomass (fbb), liquid fossil (fliq.fossil) and coal (fcoal). The aerosol samples were collected at three types of sites with distinctly different degree of air pollution: urban, rural and regional background. The seasonal variation of source apportionment of the carbonaceous aerosols in urban Beijing was discussed. Modern biogenic and biomass made an absolute dominance of 92.9 ± 0.5% contribution to the carbonaceous aerosols at the background site Mt. Yulong due to long-range transport from Southeast Asia. The three main sources contributed jointly to the atmospheric carbonaceous aerosols at the rural site Wangdu and the urban site Beijing. The biogenic and biomass source was the major contribution in summer (47.0 ± 0.3%) and autumn (49.3 ± 0.3%) of Beijing, while coal source increased from summer (26.8 ± 13.8%) to autumn (34.7 ± 11.5%). Heating significantly increased the coal source to the dominant contribution (47.0 ± 16.9%) in winter of Beijing. Separate day and night time coal contributions were used to evaluate the two origins of coal combustion: industrial use vs. residential use. The results of source apportionment for carbonaceous aerosols provide scientific support for the prevention and control of air pollution.

Seasonal variations and source apportionment of carbonaceous aerosol in PM2.5 from a coal mining city in the North China Plain

Handan is one of the most polluted coal mining cities in the North China Plain (NCP). There is a lack of research on the pollution characteristics and sources of carbonaceous components in PM2.5 in Handan city. Atmospheric PM2.5 samples were collected from Handan City during 2018 and the organic carbon (OC) and elemental carbon (EC) in PM2.5 were analyzed with a carbon analyzer. The annual average mass concentrations of PM2.5 and total carbon (TC = OC + EC) in Handan were (101.88 ± 79.01) μg/m3 and (28.03 ± 23.28) μg/m3, respectively. The annual average ratio of TC/PM2.5 was (28.29% ± 7.95%), indicating that carbonaceous components made a major contribution to PM2.5. The seasonal variations of OC and EC concentrations in PM2.5 were consistent with PM2.5, which was higher in winter and lower in summer. The annual average OC/EC ratio was (10.33 ± 5.83), and the (OC/EC)min ratio for each season was greater than 2, suggesting that there was probably secondary organic carbon (SOC) formation all around the year. The correlations between OC and EC during spring and winter were much more significant than during summer and autumn, which indicated that the sources of OC and EC in summer and autumn were more complex. Principal component analysis (PCA) displayed that the main sources of carbonaceous components in PM2.5 were coal combustion emission, road dust and vehicle exhaust, which may be related to coal-fired power generation and steelmaking, and coal transportation in Handan city. The potential source contribution function (PSCF) analysis demonstrated that PM2.5 and carbonaceous components in Handan city were significantly influenced by both local emissions and regional transport during the observation period.

Characterization and sources of fine carbonaceous aerosol in winter over a megacity on Indo-Gangetic plain

The characteristics and sources of carbonaceous aerosol (CA) was studied during winter in the lower atmosphere of Kolkata, a megacity situated in the lower Indo-Gangetic plain region. The city air was laden with typically high EC (15.4 ± 9.4 μg/m3) and OC (32.2 ± 17.8 μg/m3) in winter. NASA's MERRA-2 reanalysis aerosol products underestimated PM2.5, EC, and OC with a mean bias of 41.0 ± 56.8 μg/m3, 10.1 ± 9.3 μg/m3, and 10.8 ± 18.2 μg/m3, respectively. The EC/BC ratio for the atmosphere of Kolkata was estimated to be 1.03 ± 0.50. Levoglucosan was estimated in PM2.5 as a biomass burning tracer (266.9 ± 189.5 ng/m3). Source apportionment of CA using the tracer method indicated 43% of CA (19% of total PM2.5) was of secondary origin. 49% of total CA (21% of PM2.5) was from fossil fuel combustion, consisting of 23% of EC and 26% OC. Biomass burning contributed to 8% of CA and 3% of PM2.5. The diel trend of EC indicated equivalent primary emission throughout the day except being significantly high in the morning time during rush hours of traffic and increased residential combustion. Despite lower dispersion, OC formation was much higher during sunlight, indicating extensive secondary organic aerosol formation.

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

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.

Application of the ECT9 protocol for radiocarbon-based source apportionment of carbonaceous aerosols

Abstract. Carbonaceous aerosol is mainly composed of organic carbon (OC) and elemental carbon (EC). Both OC and EC originate from a variety of emission sources. Radiocarbon (14C) analysis can be used to apportion bulk aerosol, OC, and EC into their sources. However, such analyses require the physical separation of OC and EC. Here, we apply of ECT9 protocol to physically isolate OC and EC for 14C analysis and evaluate its effectiveness. Several reference materials are selected, including two pure OC (fossil “adipic acid” and contemporary “sucrose”), two pure EC (fossil “regal black” and “C1150”), and three complex materials containing contemporary and/or fossil OC and EC (“rice char”, NIST urban dust standards “SRM1649a” and “SRM8785”, i.e., fine fraction of resuspended SRM1649a on filters). The pure materials were measured for their OC, EC, and total carbon (TC) mass fractions and corresponding carbon isotopes to evaluate the uncertainty of the procedure. The average accuracy of TC mass, determined via volumetric injection of a sucrose solution, was approximately 5 %. Ratios of EC/TC and OC/TC were highly reproducible, with analytical precisions better than 2 % for all reference materials, ranging in size from 20 to 100 µg C. Consensus values were reached for all pure reference materials for both δ13C and fraction modern (F14C), with an uncertainty of &lt; 0.3 ‰ and approximately 5 %, respectively. The procedure introduced 1.3 ± 0.6 µg of extraneous carbon, an amount compatible to that of the Swiss_4S protocol. In addition, OC and EC were isolated from mixtures of pure contemporary OC (sucrose) with pure fossil EC (regal black) and fossil OC (adipic acid) with contemporary EC (rice char EC) to evaluate the effectiveness of OC and EC separation. Consensus F14C values were reached for all OC (∼ 5–30 µg) and EC (∼ 10–60 µg) fractions with an uncertainty of ∼ 5 % on average. We found that the ECT9 protocol efficiently isolates OC or EC from complex mixtures. Based on δ13C measurements, the average contribution of charred OC to EC is likely less than 3 % when the OC loading amount is less than 30 µg C. Charring was further assessed by evaluating thermograms of various materials, including aerosol samples collected in the Arctic and from tailpipes of gasoline or diesel engines. These data demonstrate that the ECT9 method effectively removes pyrolyzed OC. Thus, the ECT9 protocol, initially developed for concentration and stable isotope measurements of OC and EC, is suitable for 14C-based apportionment studies, including µg C-sized samples from arctic environments.

Characterization and source apportionment of carbonaceous aerosols in fine particles at urban and suburban atmospheres of Ankara, Turkey.

In order to find the spatial distribution characteristics of elemental (EC) and organic (OC) carbon in fine particles, daily PM2.5 aerosol samples were collected at two different stations, between July 2014 and September 2015 in Ankara, Turkey. Concentrations of OC ranged from 2.1 to 42 μg m-3 at urban station. These concentrations were higher than those obtained for suburban station whose values ranged from 1.3 to 15 μg m-3. Concentrations of EC ranged from 0.7 to 4.9 μg m-3 at the urban station. As in OC case, the corresponding levels were higher than those measured for suburban station. The associated EC levels ranged from 0.1 to 3.4 μg m-3 for the suburban station. Daily changes in the levels of EC were larger than the OC levels. OC/EC ratios were lower with lower monthly variability in summer and higher with lower monthly variability in winter at the urban site. Medium and weak correlations were obtained between EC and OC in the winter and summer seasons, respectively, at both stations. Secondary organic carbon (SOC) was an important component of OC in PM2.5 at the urban and suburban sites. The winter SOC level was higher than the summer SOC level at the urban site but slightly lower than the summer SOC level at the suburban site. Total carbon was apportioned using factor analysis for the eight carbon fraction data (OC1, OC2, OC3, OC4, EC1, EC2, EC3, and OP). The main sources of pollutants in the urban and suburban settings were from vehicular emissions, biomass and coal combustions, and road dust.

Analysis of Absorption Characteristics and Source Apportionment of Carbonaceous Aerosol in Arid Region of Western India

The present work analyses the equivalent Black Carbon (EBC) data obtained using Aethalometer (AE-33) located at India Meteorological Department, Jodhpur, Rajasthan during the year 2016. The annual mean EBC concentration is 5.76 µg m−3 and the monthly mean concentration is maximum (12.12 µg m−3) in January and minimum (1.27 µg m−3) in December. The seasonal mean of wind speeds are 1.94, 2.02, 1.34, 1.02 m s−1 and the calm percentages are 7, 5.7, 28.7, 25.7% during pre-monsoon (MAM), monsoon (JJAS), post-monsoon (ON) and winter (DJF), respectively. The night time EBC concentrations are more than the day time concentrations due to the shallowness of the boundary layer and local anthropogenic activities. The Concentrated Weighted Trajectories (CWT) are calculated using back trajectories ending at 100 m above ground level at Jodhpur station using National Centre for Medium Range Weather Forecast (NCMRWF) Global Forecast System (GFS) based reanalysis T574 data. The CWT, directional source region analysis reveals the effect of long-range transport in the winter season with a 60% of probability of source regions from the W, NW direction of observational site. Source apportionment also carried out by assuming alpha (at 470-, 950-nm wavelengths) close to 1 for anthropogenic emissions and alpha close to 2 for biomass burning aerosols. The monthly mean biomass burning concentration is found maximum (2.58 µg m−3) in November and minimum (0.22 µg m−3) in July.

Source apportionment of carbonaceous aerosols during haze days in Shanghai based on dual carbon isotopes

We present dual carbon isotope constrained (δ13C and Δ14C) source apportionment of organic carbon and elemental carbon in fine particulate matter (PM2.5) for five districts of Shanghai during the winter of 2013. The results show that spatial variations of the three source (biomass, liquid fossil fuel, and coal) apportionment of carbonaceous aerosol among different districts were evident. Overall, coal combustion, liquid fossil fuel combustion and biomass burning are the most important carbonaceous aerosols source in Pudong, Xuhui and Chongming, respectively. The results suggest that environmental protection policies should vary according to the functional areas of different sources in the same city.