scholarly journals Organic aerosol source apportionment by offline-AMS over a full year in Marseille

2017 ◽  
Author(s):  
Carlo Bozzetti ◽  
Imad El Haddad ◽  
Dalia Salameh ◽  
Kaspar Rudolf Daellenbach ◽  
Paola Fermo ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Air Quality ◽  
Mediterranean Sea ◽  
Source Apportionment ◽  
Organic Aerosol ◽  
Aerodynamic Diameter ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Aerosol Source

Abstract. We investigated the seasonal trends of OA sources affecting the air quality of Marseille (France) which is the largest harbor of the Mediterranean Sea. This was achieved by measurements of nebulized filter extracts using an aerosol mass spectrometer (offline-AMS). PM2.5 (particulate matter with an aerodynamic diameter

scholarly journals New insights into PM<sub>2.5</sub> chemical composition and sources in two major cities in China during extreme haze events using aerosol mass spectrometry

2016 ◽  
Vol 16 (5) ◽  
pp. 3207-3225 ◽  
Author(s):  
Miriam Elser ◽  
Ru-Jin Huang ◽  
Robert Wolf ◽  
Jay G. Slowik ◽  
Qiyuan Wang ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Solution Space ◽  
Primary Sources ◽  
Aerodynamic Diameter ◽  
Data Set ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Aerosol Mass Spectrometry ◽  
Polycyclic Aromatic ◽  
On Line

Abstract. During winter 2013–2014 aerosol mass spectrometer (AMS) measurements were conducted for the first time with a novel PM2.5 (particulate matter with aerodynamic diameter  ≤ 2.5 µm) lens in two major cities of China: Xi'an and Beijing. We denote the periods with visibility below 2 km as extreme haze and refer to the rest as reference periods. During the measurements in Xi'an an extreme haze covered the city for about a week and the total non-refractory (NR)-PM2.5 mass fraction reached peak concentrations of over 1000 µg m−3. During the measurements in Beijing two extreme haze events occurred, but the temporal extent and the total concentrations reached during these events were lower than in Xi'an. Average PM2.5 concentrations of 537 ± 146 and 243 ± 47 µg m−3 (including NR species and equivalent black carbon, eBC) were recorded during the extreme haze events in Xi'an and Beijing, respectively. During the reference periods the measured average concentrations were 140 ± 99 µg m−3 in Xi'an and 75 ± 61 µg m−3 in Beijing. The relative composition of the NR-PM2.5 evolved substantially during the extreme haze periods, with increased contributions of the inorganic components (mostly sulfate and nitrate). Our results suggest that the high relative humidity present during the extreme haze events had a strong effect on the increase of sulfate mass (via aqueous phase oxidation of sulfur dioxide). Another relevant characteristic of the extreme haze is the size of the measured particles. During the extreme haze events, the AMS showed much larger particles, with a volume weighted mode at about 800 to 1000 nm, in contrast to about 400 nm during reference periods. These large particle sizes made the use of the PM2.5 inlet crucial, especially during the severe haze events, where 39 ± 5 % of the mass would have been lost in the conventional PM1 (particulate matter with aerodynamic diameter ≤ 1 µm) inlet. A novel positive matrix factorization procedure was developed to apportion the sources of organic aerosols (OA) based on their mass spectra using the multilinear engine (ME-2) controlled via the source finder (SoFi). The procedure allows for an effective exploration of the solution space, a more objective selection of the best solution and an estimation of the rotational uncertainties. Our results clearly show an increase of the oxygenated organic aerosol (OOA) mass during extreme haze events. The contribution of OOA to the total OA increased from the reference to the extreme haze periods from 16.2 ± 1.1 to 31.3 ± 1.5 % in Xi'an and from 15.7 ± 0.7 to 25.0 ± 1.2 % in Beijing. By contrast, during the reference periods the total OA mass was dominated by domestic emissions of primary aerosols from biomass burning in Xi'an (42.2 ± 1.5 % of OA) and coal combustion in Beijing (55.2 ± 1.6 % of OA). These two sources are also mostly responsible for extremely high polycyclic aromatic hydrocarbon (PAH) concentrations measured with the AMS (campaign average of 2.1 ± 2.0 µg m−3 and frequent peak concentrations above 10 µg m−3). To the best of our knowledge, this is the first data set where the simultaneous extraction of these two primary sources could be achieved in China by conducting on-line AMS measurements at two areas with contrasted emission patterns.

scholarly journals Technical note: A new approach to discriminate different black carbon sources by utilising fullerene and metals in positive matrix factorisation analysis of high-resolution soot particle aerosol mass spectrometer data

2021 ◽  
Vol 21 (13) ◽  
pp. 10763-10777
Author(s):  
Zainab Bibi ◽  
Hugh Coe ◽  
James Brooks ◽  
Paul I. Williams ◽  
Ernesto Reyes-Villegas ◽  
...  
Keyword(s):  
High Resolution ◽  
Black Carbon ◽  
Source Apportionment ◽  
Atmospheric Aerosol ◽  
Soot Particle ◽  
Organic Aerosol ◽  
Positive Matrix ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Matrix Factorisation

Abstract. Atmospheric aerosol particles are known to have detrimental effects on human health and climate. Black carbon is an important constituent of atmospheric aerosol particulate matter (PM), emitted from incomplete combustion. Source apportionment of BC is very important, to evaluate the influence of different sources. The high-resolution soot particle aerosol mass spectrometer (HR-SP-AMS) instrument uses a laser vaporiser, which allows the real-time detection and characterisation of refractory black carbon (rBC) and its internally mixed particles such as metals, coating species, and rBC subcomponents in the form of HOA + fullerene. In this case study, the soot data were collected by using HR-SP-AMS during Guy Fawkes Night on 5 November 2014. Positive matrix factorisation was applied to positively discriminate between different wood-burning and bonfire sources for the first time, which no existing black carbon source apportionment technique is currently able to do. Along with this, the use of the fullerene signals in differentiating between soot sources and the use of metals as a tracer for fireworks has also been investigated, which did not significantly contribute to the rBC concentrations. The addition of fullerene signals and successful positive matrix factorisation (PMF) application to HR-SP-AMS data apportioned rBC into more than two sources. These bonfire sources are HOA + fullerene, biomass burning organic aerosol, more oxidised oxygenated organic aerosol (MO-OOA), and non-bonfire sources such as hydrocarbon-like OA and domestic burning. The result of correlation analysis between HR-SP-AMS data and previously published Aethalometer, MAAP, and CIMS data provides an effective way of gaining insights into the relationships between the variables and provide a quantitative estimate of the source contributions to the BC budget during this period. This research study is an important demonstration of using HR-SP-AMS for the purpose of BC source apportionment.

Source apportionment of time- and size-resolved particulate matter over two sites in New Delhi & NCR

2020 ◽  
Author(s):  
Suneeti Mishra ◽  
Sachchida Tripathi ◽  
Navaneeth Thamban ◽  
Vipul Lalchandani ◽  
Varun Kumar ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Source Apportionment ◽  
Mass Spectrometer ◽  
Time Of Flight ◽  
Aerosol Mass Spectrometer ◽  
Ambient Aerosol ◽  
Atmospheric Processes ◽  
Aerosol Mass ◽  
Individual Site ◽  
Institute Of Technology

&lt;p&gt;Size resolved data of chemical species carries a lot of latent information about the sources and atmospheric processes which lead to their formation and growth. Source apportionment techniques on organic or inorganic aerosols provide a fair amount of information about the sources but this analysis only provides a partial picture owing to the complicated nature of the ambient aerosols which may contain both, organic as well as inorganic particulate matter. Traditionally, potential emission sources are distinguished by either the organic or inorganic tracers present in ambient aerosol, but recently several studies have performed PMF on both the species (Sun et al, 2012). However, it tells more about the final transformed products which could be formed from different pathways but not much about the transformation pathways. Insights about the source and the atmospheric processes involved can be derived from the analysis of size-resolved data of the ambient aerosol. PMF on Size-resolved information helps us to narrow down the possible pathways of the transformed products.&lt;/p&gt;&lt;p&gt;However, there is very limited literature available to help us understand more about size-resolved bulk particulate matter. In this manuscript, a novel approach to perform Positive Matrix Factorization (PMF) on real-time size-resolved Unit Mass Resolution (UMR) data from Aerosol Mass Spectrometer (AMS) is presented. Both size- and time-resolved PMF is performed on non-refractory particle composition (organic &amp; inorganic) on the UMR PTOF data of two sites in one of the most polluted cities in the world. The sampling through Long Time of flight mass spectrometer (LToF-AMS) was carried out at Indian Institute of Technology, Delhi which is located in Hauz Khaz area, at the heart of Delhi NCR, whereas parallel sampling through High-resolution Time of flight aerosol mass spectrometer (HR-ToF-AMS) was carried out at Manav Rachna University which is located in Faridabad within Delhi NCR at a downwind location. PMF was performed on the data by using Multi-linear Engine (ME-2) on PMF model by SoFi (Source Finder) tool. A seven-factor solution was chosen based on the factor profiles, time series, diurnals and correlation with the external factors obtained by supplementary instruments. The size-resolved spectra of the species at an individual site was studied and the difference between the sites was compared.&lt;/p&gt;

scholarly journals Characterization and source apportionment of organic aerosol using offline aerosol mass spectrometry

2016 ◽  
Vol 9 (1) ◽  
pp. 23-39 ◽  
Author(s):  
K. R. Daellenbach ◽  
C. Bozzetti ◽  
A. Křepelová ◽  
F. Canonaco ◽  
R. Wolf ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Source Apportionment ◽  
Organic Aerosol ◽  
Transmission Efficiency ◽  
Water Soluble ◽  
Spatially Resolved ◽  
Aerosol Mass ◽  
Online Measurements ◽  
Rural Sites ◽  
Pm2.5 And Pm10

Abstract. Field deployments of the Aerodyne Aerosol Mass Spectrometer (AMS) have significantly advanced real-time measurements and source apportionment of non-refractory particulate matter. However, the cost and complex maintenance requirements of the AMS make its deployment at sufficient sites to determine regional characteristics impractical. Furthermore, the negligible transmission efficiency of the AMS inlet for supermicron particles significantly limits the characterization of their chemical nature and contributing sources. In this study, we utilize the AMS to characterize the water-soluble organic fingerprint of ambient particles collected onto conventional quartz filters, which are routinely sampled at many air quality sites. The method was applied to 256 particulate matter (PM) filter samples (PM1, PM2.5, and PM10, i.e., PM with aerodynamic diameters smaller than 1, 2.5, and 10 µm, respectively), collected at 16 urban and rural sites during summer and winter. We show that the results obtained by the present technique compare well with those from co-located online measurements, e.g., AMS or Aerosol Chemical Speciation Monitor (ACSM). The bulk recoveries of organic aerosol (60–91 %) achieved using this technique, together with low detection limits (0.8 µg of organic aerosol on the analyzed filter fraction) allow its application to environmental samples. We will discuss the recovery variability of individual hydrocarbon ions, ions containing oxygen, and other ions. The performance of such data in source apportionment is assessed in comparison to ACSM data. Recoveries of organic components related to different sources as traffic, wood burning, and secondary organic aerosol are presented. This technique, while subjected to the limitations inherent to filter-based measurements (e.g., filter artifacts and limited time resolution) may be used to enhance the AMS capabilities in measuring size-fractionated, spatially resolved long-term data sets.

scholarly journals ACTRIS ACSM intercomparison – Part 2: Intercomparison of ME-2 organic source apportionment results from 15 individual, co-located aerosol mass spectrometers

2015 ◽  
Vol 8 (2) ◽  
pp. 1559-1613 ◽  
Author(s):  
R. Fröhlich ◽  
V. Crenn ◽  
A. Setyan ◽  
C. A. Belis ◽  
F. Canonaco ◽  
...  
Keyword(s):  
Source Apportionment ◽  
Organic Aerosol ◽  
Data Sets ◽  
Mass Spectrometers ◽  
Aerosol Mass Spectrometer ◽  
Average Mass ◽  
Aerosol Mass ◽  
Accuracy And Precision ◽  
The Mean ◽  
A Minor

Abstract. Chemically resolved atmospheric aerosol data sets from the largest intercomparison of the Aerodyne aerosol chemical speciation monitors (ACSM) performed to date were collected at the French atmospheric supersite SIRTA. In total 13 quadrupole ACSMs (Q-ACSM) from the European ACTRIS ACSM network, one time-of-flight ACSM (ToF-ACSM), and one high-resolution ToF aerosol mass spectrometer (AMS) were operated in parallel for about three weeks in November and December 2013. Part 1 of this study reports on the accuracy and precision of the instruments for all the measured species. In this work we report on the intercomparison of organic components and the results from factor analysis source apportionment by positive matrix factorisation (PMF) utilising the multilinear engine 2 (ME-2). Except for the organic contribution of m/z 44 to the total organics (f44), which varied by factors between 0.6 and 1.3 compared to the mean, the peaks in the organic mass spectra were similar among instruments. The m/z 44 differences in the spectra resulted in a variable f44 in the source profiles extracted by ME-2, but had only a minor influence on the extracted mass contributions of the sources. The presented source apportionment yielded four factors for all 15 instruments: hydrocarbon-like organic aerosol (HOA), cooking-related organic aerosol (COA), biomass burning-related organic aerosol (BBOA) and secondary oxygenated organic aerosol (OOA). Individual application and optimisation of the ME-2 boundary conditions (profile constraints) are discussed together with the investigation of the influence of alternative anchors (reference profiles). A comparison of the ME-2 source apportionment output of all 15 instruments resulted in relative SD from the mean between 13.7 and 22.7% of the source's average mass contribution depending on the factors (HOA: 14.3 ± 2.2%, COA: 15.0 ± 3.4%, OOA: 41.5 ± 5.7%, BBOA: 29.3 ± 5.0%). Factors which tend to be subject to minor factor mixing (in this case COA) have higher relative uncertainties than factors which are recognised more readily like the OOA. Averaged over all factors and instruments the relative first SD from the mean of a source extracted with ME-2 was 17.2%.

scholarly journals Organic aerosol components derived from 25 AMS data sets across Europe using a consistent ME-2 based source apportionment approach

2014 ◽  
Vol 14 (12) ◽  
pp. 6159-6176 ◽  
Author(s):  
M. Crippa ◽  
F. Canonaco ◽  
V. A. Lanz ◽  
M. Äijälä ◽  
J. D. Allan ◽  
...  
Keyword(s):  
Source Apportionment ◽  
Monitoring And Evaluation ◽  
Organic Aerosol ◽  
Data Sets ◽  
Time Resolved ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Ambient Data ◽  
Aerosol Sources ◽  
Different Sources

Abstract. Organic aerosols (OA) represent one of the major constituents of submicron particulate matter (PM1) and comprise a huge variety of compounds emitted by different sources. Three intensive measurement field campaigns to investigate the aerosol chemical composition all over Europe were carried out within the framework of the European Integrated Project on Aerosol Cloud Climate and Air Quality Interactions (EUCAARI) and the intensive campaigns of European Monitoring and Evaluation Programme (EMEP) during 2008 (May–June and September–October) and 2009 (February–March). In this paper we focus on the identification of the main organic aerosol sources and we define a standardized methodology to perform source apportionment using positive matrix factorization (PMF) with the multilinear engine (ME-2) on Aerodyne aerosol mass spectrometer (AMS) data. Our source apportionment procedure is tested and applied on 25 data sets accounting for two urban, several rural and remote and two high altitude sites; therefore it is likely suitable for the treatment of AMS-related ambient data sets. For most of the sites, four organic components are retrieved, improving significantly previous source apportionment results where only a separation in primary and secondary OA sources was possible. Generally, our solutions include two primary OA sources, i.e. hydrocarbon-like OA (HOA) and biomass burning OA (BBOA) and two secondary OA components, i.e. semi-volatile oxygenated OA (SV-OOA) and low-volatility oxygenated OA (LV-OOA). For specific sites cooking-related (COA) and marine-related sources (MSA) are also separated. Finally, our work provides a large overview of organic aerosol sources in Europe and an interesting set of highly time resolved data for modeling purposes.

scholarly journals Identification and quantification of organic aerosol from cooking and other sources in Barcelona using aerosol mass spectrometer data

2012 ◽  
Vol 12 (4) ◽  
pp. 1649-1665 ◽  
Author(s):  
C. Mohr ◽  
P. F. DeCarlo ◽  
M. F. Heringa ◽  
R. Chirico ◽  
J. G. Slowik ◽  
...  
Keyword(s):  
Air Quality ◽  
Mass Spectrometer ◽  
Biomass Burning ◽  
Ambient Air ◽  
Organic Aerosol ◽  
Data Matrix ◽  
High Mass ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Data Points

Abstract. PM1 (particulate matter with an aerodynamic diameter <1 μm) non-refractory components and black carbon were measured continuously together with additional air quality and atmospheric parameters at an urban background site in Barcelona, Spain, during March 2009 (campaign DAURE, Determination of the sources of atmospheric Aerosols in Urban and Rural Environments in the western Mediterranean). Positive matrix factorization (PMF) was conducted on the organic aerosol (OA) data matrix measured by an aerosol mass spectrometer, on both unit mass (UMR) and high resolution (HR) data. Five factors or sources could be identified: LV-OOA (low-volatility oxygenated OA), related to regional, aged secondary OA; SV-OOA (semi-volatile oxygenated OA), a fresher oxygenated OA; HOA (hydrocarbon-like OA, related to traffic emissions); BBOA (biomass burning OA) from domestic heating or agricultural biomass burning activities; and COA (cooking OA). LV-OOA contributed 28% to OA, SV-OOA 27%, COA 17%, HOA 16%, and BBOA 11%. The COA HR spectrum contained substantial signal from oxygenated ions (O:C: 0.21) whereas the HR HOA spectrum had almost exclusively contributions from chemically reduced ions (O:C: 0.03). If we assume that the carbon in HOA is fossil while that in COA and BBOA is modern, primary OA in Barcelona contains a surprisingly high fraction (59%) of non-fossil carbon. This paper presents a method for estimating cooking organic aerosol in ambient datasets based on the fractions of organic mass fragments at m/z 55 and 57: their data points fall into a V-shape in a scatter plot, with strongly influenced HOA data aligned to the right arm and strongly influenced COA data points aligned to the left arm. HR data show that this differentiation is mainly driven by the oxygen-containing ions C3H3O+ and C3H5O+, even though their contributions to m/z 55 and 57 are low compared to the reduced ions C4H7+ and C4H9+. A simple estimation method based on the markers m/z 55, 57, and 44 is developed here and allows for a first-order-estimation of COA in urban air. This study emphasizes the importance of cooking activities for ambient air quality and confirms the importance of chemical composition measurements with a high mass and time resolution.

scholarly journals Sources and atmospheric processing of wintertime aerosols in Seoul, Korea: Insights from real-time measurements using a high-resolution aerosol mass spectrometer

2016 ◽  
Author(s):  
Hwajin Kim ◽  
Qi Zhang ◽  
Gwi-Nam Bae ◽  
Jin Young Kim ◽  
Seung Bok Lee
Keyword(s):  
Particulate Matter ◽  
High Resolution ◽  
Real Time ◽  
Mass Spectrometer ◽  
Organic Aerosol ◽  
Meteorological Conditions ◽  
Emission Sources ◽  
Aerosol Mass Spectrometer ◽  
Atmospheric Processes ◽  
Aerosol Mass

Abstract. Highly time-resolved chemical characterization of non-refractory submicrometer particulate matter (NR-PM1) was conducted in Seoul, the capital and largest metropolis of Korea, using an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). The measurements were performed during winter, when elevated particulate matter (PM) pollution events are often observed. This is the first time that detailed real-time aerosol measurement results are reported from Seoul, Korea, which reveal valuable insights into the sources and atmospheric processes that contribute to PM pollution in this region. The average concentration of submicron aerosol (PM1 = NR - PM1 + black carbon (BC)) was 27.5 µg m−3, and the total mass was dominated by organics (44 %), followed by nitrate (24 %) and sulfate (10 %). The average atomic ratios of oxygen-to-carbon (O / C), hydrogen-to-carbon (H / C), and nitrogen-to-carbon (N / C) of organic aerosol (OA) were 0.37, 1.79, and 0.022, respectively, which gives that average organic mass-to-carbon (OM / OC) ratio of 1.67. The concentrations (2.6–90.7 µg m−3) and composition of PM1 varied dynamically during the measurement period, due to the influences of different meteorological conditions, emission sources, and air mass origins. Five distinct sources of OA were identified via positive matrix factorization (PMF) analysis of the HR-ToF-AMS data: vehicle emissions represented by a hydrocarbon like OA factor (HOA; O / C = 0.06), cooking activities represented by a cooking OA factor (COA; O / C = 0.15), wood combustion represented by a biomass burning OA factor (BBOA; O / C = 0.34), and secondary organic aerosol (SOA) represented by a semi-volatile oxygenated OA factor (SV-OOA; O / C = 0.56) and a low volatility oxygenated OA factor (LV-OOA; O / C = 0.68). On average, primary OA (POA = HOA + COA + BBOA) accounted for 59 % the OA mass whereas SV-OOA and LV-OOA contributed 15 % and 26 %, respectively. Our results indicate that air quality in Seoul during winter is influenced strongly by secondary aerosol formation with sulfate, nitrate, ammonium, SV-OOA, and LV-OOA together accounting for 64 % of the PM1 mass during this study. However, aerosol sources and composition were found to be significantly different between clean and polluted periods. During stagnant periods with low wind speed (WS) and high relative humidity (RH), PM concentration was generally high (average ± 1σ = 43.6 ± 12.4 µg m−3) with enhanced fractions of nitrate (27 %) and SV-OOA (8 %), which suggested a strong influence from local production of secondary aerosol. Low PM loading periods (12.6 ± 7.1 µg m−3) tended to occurred under higher WS and lower RH conditions and appeared to be more strongly influenced by regional air masses, as indicated by higher mass fractions of sulfate (12 %) and LV-OOA (21 %) in PM1. Overall, our results indicate that PM pollutants in urban Korea originate from complex emission sources and atmospheric processes and that their concentrations and composition are controlled by various factors including meteorological conditions, local anthropogenic emissions, and upwind sources.

scholarly journals Organic aerosol components derived from 25 AMS datasets across Europe using a newly developed ME-2 based source apportionment strategy

2013 ◽  
Vol 13 (9) ◽  
pp. 23325-23371 ◽  
Author(s):  
M. Crippa ◽  
F. Canonaco ◽  
V. A. Lanz ◽  
M. Äijälä ◽  
J. D. Allan ◽  
...  
Keyword(s):  
Source Apportionment ◽  
Organic Aerosol ◽  
Time Resolved ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Urban Rural ◽  
Multilinear Engine ◽  
Aerosol Sources ◽  
Field Campaigns ◽  
Different Sources

Abstract. Organic aerosols (OA) represent one of the major constituents of submicron particulate matter (PM1) and comprise a huge variety of compounds emitted by different sources. Three intensive measurement field campaigns to investigate the aerosol chemical composition all over Europe were carried out within the framework of EUCAARI and the intensive campaigns of EMEP during 2008 (May–June and September–October) and 2009 (February–March). In this paper we focus on the identification of the main organic aerosol sources and we propose a standardized methodology to perform source apportionment using positive matrix factorization (PMF) with the multilinear engine (ME-2) on Aerodyne aerosol mass spectrometer (AMS) data. Our source apportionment procedure is tested and applied on 25 datasets accounting for urban, rural, remote and high altitude sites and therefore it is likely suitable for the treatment of AMS-related ambient datasets. For most of the sites, four organic components are retrieved, improving significantly previous source apportionment results where only a separation in primary and secondary OA sources was possible. Our solutions include two primary OA sources, i.e. hydrocarbon-like OA (HOA) and biomass burning OA (BBOA) and two secondary OA components, i.e. semi-volatile oxygenated OA (SV-OOA) and low-volatility oxygenated OA (LV-OOA). For specific sites cooking-related (COA) and marine-related sources (MSA) are also separated. Finally, our work provides a large overview of organic aerosol sources in Europe and an interesting set of highly time resolved data for modeling evaluation purposes.

scholarly journals PM<sub>1</sub> composition and source apportionment at two sites in Delhi, India, across multiple seasons

2021 ◽  
Vol 21 (15) ◽  
pp. 11655-11667
Author(s):  
Ernesto Reyes-Villegas ◽  
Upasana Panda ◽  
Eoghan Darbyshire ◽  
James M. Cash ◽  
Rutambhara Joshi ◽  
...  
Keyword(s):  
Air Quality ◽  
Black Carbon ◽  
Source Apportionment ◽  
Organic Aerosols ◽  
Urban Environments ◽  
Significant Information ◽  
Post Monsoon ◽  
Aerosol Mass ◽  
Significant Difference ◽  
Aerosol Source

Abstract. Air pollution in urban environments has been shown to have a negative impact on air quality and human health, particularly in megacities. Over recent decades, Delhi, India, has suffered high atmospheric pollution, with significant particulate matter (PM) concentrations as a result of anthropogenic activities. Organic aerosols (OAs) are composed of thousands of different chemical species and are one of the main constituents of submicron particles. However, quantitative knowledge of OA composition, their sources and their processes in urban environments is still limited. This is important particularly in India, as Delhi is a massive, inhomogeneous conurbation, where we would expect the apportionment and concentrations to vary depending on where in Delhi the measurements/source apportionment is performed, indicating the need for multisite measurements. This study presents the first multisite analysis carried out in India over different seasons, with a focus on identifying OA sources. The measurements were taken during 2018 at two sites in Delhi, India. One site was located at the India Meteorological Department, New Delhi (ND). The other site was located at the Indira Gandhi Delhi Technical University for Women, Old Delhi (OD). Non-refractory submicron aerosol (NR-PM1) concentrations (ammonium, nitrate, sulfate, chloride and organic aerosols) of four aerosol mass spectrometers were analysed. Collocated measurements of volatile organic compounds, black carbon, NOx and CO were performed. Positive matrix factorisation (PMF) analysis was performed to separate the organic fraction, identifying a number of conventional factors: hydrocarbon-like OAs (HOAs) related to traffic emissions, biomass burning OAs (BBOAs), cooking OAs (COAs) and secondary OAs (SOAs). A composition-based estimate of PM1 is defined by combining black carbon (BC) and NR-PM1 (C-PM1= BC + NR-PM1). No significant difference was observed in C-PM1 concentrations between sites, OD (142 ± 117 µg m−3) compared to ND (123 ± 71 µg m3), from post-monsoon measurements. A wider variability was observed between seasons, where pre-monsoon and monsoon showed C-PM1 concentrations lower than 60 µg m−3. A seasonal variation in C-PM1 composition was observed; SO42- showed a high contribution over pre-monsoon and monsoon seasons, while NO3- and Cl− had a higher contribution in winter and post-monsoon. The main primary aerosol source was from traffic, which is consistent with the PMF analysis and Aethalometer model analysis. Thus, in order to reduce PM1 concentrations in Delhi through local emission controls, traffic emission control offers the greatest opportunity. PMF–aerosol mass spectrometer (AMS) mass spectra will help to improve future aerosol source apportionment studies. The information generated in this study increases our understanding of PM1 composition and OA sources in Delhi, India. Furthermore, the scientific findings provide significant information to strengthen legislation that aims to improve air quality in India.

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