Sources and characteristics of light-absorbing fine particulates over Delhi through the synergy of real-time optical and chemical measurements

Singh, Atinderpal; Rastogi, Neeraj; Kumar, Varun; Slowik, Jay G.; Satish, Rangu; Lalchandani, Vipul; Thamban, Navaneeth M.; Rai, Pragati; Bhattu, Deepika; Vats, Pawan; Ganguly, Dilip; Tripathi, Sachchida Nand; Prévôt, Andrê S. H.

doi:10.1016/j.atmosenv.2021.118338

Cited by 25 publications

(21 citation statements)

References 65 publications

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“…As observed by Lalchandani et al at the IITDelhi site during the study period of mid-January to mid-March 2018, the fractional contributions from traffic emissions and biomass burning emissions were ~67.5% and ~32.5% of the total BC concentration, respectively, whereas at the IITMDelhi site, for the same study period, the contribution fractions of traffic emissions and biomass burning emissions were ~55.7% and ~44.3%, respectively [10]. Singh et al discussed that so far, BC was considered the only light-absorbing aerosol, and OC was considered to be a light-scattering aerosol [15]. Recent studies reported that a fraction of organic aerosols also absorbed light in the near-UV to the visible region, and thus such fraction of organic aerosols was categorized as brown carbon (BrC) [34].…”

Section: Source Apportionment Of Bcmentioning

confidence: 98%

“…The common period in all these studies was between mid-January andmid-March of 2018, which is considered the late winter period. Most importantly, all these studies investigated the chemical composition and source apportionment of fine particulate matter, carbonaceous aerosols, elements in aerosols, and gaseous volatile organic compounds (VOCs) [10][11][12][13][14][15]. More specifically, Tobler et al and Lalchandani et al studied the highly time-resolved chemical characterization of fine particulate matter and source apportionment of organic aerosols and black carbon [10,11].…”

Section: Introductionmentioning

confidence: 99%

“…Rai et al worked on the quantification, chemical composition, and source apportionment of highly time-resolved elements in PM 10 and PM 2.5 (with an aggregate mass of particles with aerodynamic diameter less or equal to 10 µm and 2.5 µm, respectively) [12]. Temporal and spatial variability of carbonaceous species in PM 2.5 was studied by Bhowmik et al using filter sampling at five sites on the Indo-Gangetic Plain (IGP) and their offline analysis [14]; and very recently, characteristics and sources of light-absorbing fine particulates were examined by Singh et al [15]. Rastogi et al, in 2021, reported on the diurnal variability in the entire spectra (300 to 600 nm) of watersoluble brown carbon (WS-BrC), which revealed many interesting features of WS-BrC [16].…”

Section: Introductionmentioning

confidence: 99%

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Air Pollution in New Delhi during Late Winter: An Overview of a Group of Campaign Studies Focusing on Composition and Sources

et al. 2021

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In recent times, a significant number of studies on the composition and sources of fine particulate matters and volatile organic compounds have been carried out over Delhi, either initiated by or in association with the researchers from the Indian Institute of Technology Kanpur (IIT Kanpur), in collaboration with researchers from within and outside India. All these studies utilized highly time-resolved, campaign-mode observations made with state-of-the-art instrumentation during the late winter months (mid-January to March) of 2018. Individually, each of these studies were rigorous in nature, containing explicit detailing about different types of ambient air pollutants in Delhi such as organic aerosols, inorganic elements, metals, carbonaceous aerosols, and volatile organic compounds. This study consolidates the extremely useful knowledge on source attribution of these air pollutants in the Delhi National Capital Region currently contained in these fragmented studies, which is vital to further enhancing our understanding of composition, characteristics, and sources of air pollutants over Delhi, as well as to designing appropriate mitigation measures tailored to local specifics.

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Section: Source Apportionment Of Bcmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Air Pollution in New Delhi during Late Winter: An Overview of a Group of Campaign Studies Focusing on Composition and Sources

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“…The vast majority of studies dealing with carbonaceous aerosols, chemical composition, and radiative effects of black carbon (BC) and brown carbon (BrC) in India have been performed over the IGP region (e.g., Delhi [22][23][24], Agra [25], Patiala [10,26], Kanpur [5,27], and Varanasi [28,29]). These studies have enhanced the current knowledge on the chemical composition, sources, seasonality, mixing processes, and radiative impacts of size-segregated aerosols.…”

Section: Introductionmentioning

confidence: 99%

Chemical Composition and Source Apportionment of Total Suspended Particulate in the Central Himalayan Region

et al. 2021

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The present study analyzes data from total suspended particulate (TSP) samples collected during 3 years (2005–2008) at Nainital, central Himalayas, India and analyzed for carbonaceous aerosols (organic carbon (OC) and elemental carbon (EC)) and inorganic species, focusing on the assessment of primary and secondary organic carbon contributions (POC, SOC, respectively) and on source apportionment by positive matrix factorization (PMF). An average TSP concentration of 69.6 ± 51.8 µg m−3 was found, exhibiting a pre-monsoon (March–May) maximum (92.9 ± 48.5 µg m−3) due to dust transport and forest fires and a monsoon (June–August) minimum due to atmospheric washout, while carbonaceous aerosols and inorganic species expressed a similar seasonality. The mean OC/EC ratio (8.0 ± 3.3) and the good correlations between OC, EC, and nss-K+ suggested that biomass burning (BB) was one of the major contributing factors to aerosols in Nainital. Using the EC tracer method, along with several approaches for the determination of the (OC/EC)pri ratio, the estimated SOC component accounted for ~25% (19.3–29.7%). Furthermore, TSP source apportionment via PMF allowed for a better understanding of the aerosol sources in the Central Himalayan region. The key aerosol sources over Nainital were BB (27%), secondary sulfate (20%), secondary nitrate (9%), mineral dust (34%), and long-range transported mixed marine aerosol (10%). The potential source contribution function (PSCF) and concentration weighted trajectory (CWT) analyses were also used to identify the probable regional source areas of resolved aerosol sources. The main source regions for aerosols in Nainital were the plains in northwest India and Pakistan, polluted cities like Delhi, the Thar Desert, and the Arabian Sea area. The outcomes of the present study are expected to elucidate the atmospheric chemistry, emission source origins, and transport pathways of aerosols over the central Himalayan region.

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“…CC BY 4.0 License. that used high time resolution methods (HR-ToF-AMS, Q-ACSM, Xact) for characterization and source apportionment of coarse and fine particulate matters (Gani et al, 2019;Lalchandani et al, 2021;Rai et al, 2020Rai et al, , 2021Singh et al, 2021;Tobler et al, 2020). Online and offline measurements both have their advantages and limitations.…”

Section: Introductionmentioning

confidence: 99%

Inter-comparison of online and offline methods for measuring ambient heavy and trace elements and water-soluble inorganic ions (NO3−, SO42−, NH4+ and Cl−) in PM2.5 over a heavily polluted megacity, D

Bhowmik

Shukla

Lalchandani

et al. 2021

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Abstract. Characterizing the chemical composition of ambient particulate matter (PM) provides valuable information on the concentration of secondary species, toxic metals and assists in the validation of abatement techniques. The chemical components of PM can be measured by sampling on filters and analysing them in the laboratory or using real-time measurements of the species. It is important for the accuracy of the PM monitoring networks that measurements from the offline and online methods are comparable and biases are known. The concentrations of water-soluble inorganic ions (NO3−, SO42−, NH4+ and Cl−) in PM2.5 measured from the 24 hrs filter samples using ion chromatography (IC) were compared with the online measurements of inorganics from aerosol mass spectrometer (AMS) with a frequency of 2 mins. Also, the concentrations of heavy and trace elements determined from the 24 hrs filter samples using inductively coupled plasma mass spectroscopy (ICP-MS) were compared with the online measurements of half-hourly heavy and trace metal’s concentrations from Xact 625i ambient metal mass monitor. The comparison was performed over two seasons (summer and winter) characterized by their different metrological conditions at IITD and during winter at IITMD, two sites located in Delhi, NCR, India, one of the heavily polluted urban areas in the world. Collocated deployments of the instruments helped to quantify the differences between online and offline measurements and evaluate the possible reasons for positive and negative biases. The slopes for SO42− and NH4+ were closer to 1:1 line during winter and decreased during summer at both sites. The higher concentrations on the filters were due to the formation of particulate (NH4)2SO4. Filter-based NO3− measurements were lower than online NO3− during summer at IITD and winter at IITMD due to the volatile nature of NO3− from the filter substrate. Offline measured Cl− was consistently higher than AMS derived Cl− during summer and winter at both sites. Based on their comparability characteristics, elements were grouped under 3 categories. The online element data were highly correlated (R2 > 0.8) with the offline measurements for Al, K, Ca, Ti, Zn, Mn, Fe, Ba, and Pb during summer at IITD and winter at both the sites. The higher correlation coefficient demonstrated the precision of the measurements of these elements by both Xact 625i and ICP-MS. Some of these elements showed higher Xact 625i elemental concentrations than ICP-MS measurements by an average of 10–40 % depending on the season and site. The reasons for the differences in the concentration of the elements could be the distance between two inlets for the two methods, line interference between two elements in Xact measurements, sampling strategy, variable concentrations of elements in blank filters and digestion protocol for ICP measurements.

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Sources and characteristics of light-absorbing fine particulates over Delhi through the synergy of real-time optical and chemical measurements

Cited by 25 publications

References 65 publications

Air Pollution in New Delhi during Late Winter: An Overview of a Group of Campaign Studies Focusing on Composition and Sources

Air Pollution in New Delhi during Late Winter: An Overview of a Group of Campaign Studies Focusing on Composition and Sources

Chemical Composition and Source Apportionment of Total Suspended Particulate in the Central Himalayan Region

Inter-comparison of online and offline methods for measuring ambient heavy and trace elements and water-soluble inorganic ions (NO<sub>3</sub><sup>−</sup>, SO<sub>4</sub><sup>2−</sup>, NH<sub>4</sub><sup>+</sup> and Cl<sup>−</sup>) in PM<sub>2.5</sub> over a heavily polluted megacity, D

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