Chemical characterization of fine particulate matter, and source apportionment of organic aerosol at three sites in New Delhi, India

Author(s):  
Sachchida Tripathi ◽  
Vipul Lalchandani ◽  
Varun Kumar ◽  
Anna Tobler ◽  
Navaneeth Thamban ◽  
...  

<p>Atmospheric particulate matter has adverse effects on human health, and causes over 4 million deaths per year globally. New Delhi was ranked as world’s most polluted megacity with annual average PM<sub>2.5</sub> concentration of ~140 ug.m<sup>-3</sup>. Thus, real time chemical characterization of fine particulate matter and identification of its sources is important for developing cost effective mitigation policies.</p><p>Highly time resolved real-time chemical composition of PM<sub>2.5</sub> was measured using Long-Time of Flight-Aerosol Mass Spectrometer (L-ToF-AMS) at Indian Institute of Technology Delhi and Time of Flight-Aerosol Chemical Speciation Monitor (ToF-ACSM) at Indian Institute of Tropical Meteorology, Delhi, and PM<sub>1 </sub>using High Resolution-Time of Flight-Aerosol Mass Spectrometer (HR-ToF-AMS) at Manav Rachna International University, Faridabad, Haryana located ~40 km downwind of Delhi during Jan-March, 2018. Black carbon concentration was measured using Aethalometer at all three sites. Unit mass resolution (UMR) and high resolution (HR) data analysis were performed on AMS and ACSM mass spectra to calculate organics, nitrate, sulfate and chloride concentrations. Positive Matrix Factorization (PMF) (Paatero and Tapper, 1994) of organic mass spectra was performed by applying multilinear engine (ME-2) algorithm using Sofi (Source finder) for identifying sources of OA.</p>

2009 ◽  
Vol 9 (11) ◽  
pp. 3709-3720 ◽  
Author(s):  
M. Dall'Osto ◽  
R. M. Harrison ◽  
H. Coe ◽  
P. I. Williams ◽  
J. D. Allan

Abstract. Nitrate aerosols make a very major contribution to PM2.5 and PM10 in western Europe, but their sources and pathways have not been fully elucidated. An Aerosol Time-of-Flight Mass Spectrometer (ATOFMS) and a Compact Time of Flight Aerosol Mass Spectrometer (C-ToF-AMS) were deployed in an urban background location in London, UK, collecting data as part of the REPARTEE-I experiment. During REPARTEE-I, daily PM10 concentrations ranged up to 43.6 μg m−3, with hourly nitrate concentrations (measured by AMS) of up to 5.3 μg m−3. The application of the ART-2a neural network algorithm to the ATOFMS data characterised the nitrate particles as occurring in two distinct clusters (i.e. particle types). The first (33.6% of particles by number) appeared to be locally produced in urban locations during nighttime, whilst the second (22.8% of particles by number) was regionally transported from continental Europe. Nitrate in locally produced aerosol was present mainly in particles smaller than 300 nm, whilst the regional nitrate presented a coarser mode, peaking at 600 nm. In both aerosol types, nitrate was found to be internally mixed with sulphate, ammonium, elemental and organic carbon. Nitrate in regional aerosol appeared to be more volatile than that locally formed. During daytime, a core of the regionally transported nitrate aerosol particle type composed of organic carbon and sulphate was detected.


2017 ◽  
Vol 17 (4) ◽  
pp. 2573-2592 ◽  
Author(s):  
Zhaolian Ye ◽  
Jiashu Liu ◽  
Aijun Gu ◽  
Feifei Feng ◽  
Yuhai Liu ◽  
...  

Abstract. Knowledge of aerosol chemistry in densely populated regions is critical for effective reduction of air pollution, while such studies have not been conducted in Changzhou, an important manufacturing base and populated city in the Yangtze River Delta (YRD), China. This work, for the first time, performed a thorough chemical characterization on the fine particulate matter (PM2.5) samples, collected during July 2015 to April 2016 across four seasons in this city. A suite of analytical techniques was employed to measure the organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), water-soluble inorganic ions (WSIIs), trace elements, and polycyclic aromatic hydrocarbons (PAHs) in PM2.5; in particular, an Aerodyne soot particle aerosol mass spectrometer (SP-AMS) was deployed to probe the chemical properties of water-soluble organic aerosol (WSOA). The average PM2.5 concentration was found to be 108.3 µg m−3, and all identified species were able to reconstruct ∼ 80 % of the PM2.5 mass. The WSIIs occupied about half of the PM2.5 mass (∼ 52.1 %), with SO42−, NO3−, and NH4+ as the major ions. On average, nitrate concentrations dominated over sulfate (mass ratio of 1.21), indicating that traffic emissions were more important than stationary sources. OC and EC correlated well with each other and the highest OC ∕ EC ratio (5.16) occurred in winter, suggesting complex OC sources likely including both secondary and primary ones. Concentrations of eight trace elements (Mn, Zn, Al, B, Cr, Cu, Fe, Pb) can contribute up to ∼ 5.0 % of PM2.5 during winter. PAH concentrations were also high in winter (140.25 ng m−3), which were predominated by median/high molecular weight PAHs with five and six rings. The organic matter including both water-soluble and water-insoluble species occupied ∼ 21.5 % of the PM2.5 mass. SP-AMS determined that the WSOA had average atomic oxygen-to-carbon (O ∕ C), hydrogen-to-carbon (H ∕ C), nitrogen-to-carbon (N ∕ C), and organic matter-to-organic carbon (OM ∕ OC) ratios of 0.54, 1.69, 0.11, and 1.99, respectively. Source apportionment of WSOA further identified two secondary OA (SOA) factors (a less oxidized and a more oxidized oxygenated OA) and two primary OA (POA) factors (a nitrogen-enriched hydrocarbon-like traffic OA and a local primary OA likely including species from cooking, coal combustion, etc.). On average, the POA contribution outweighed SOA (55 % vs. 45 %), indicating the important role of local anthropogenic emissions in the aerosol pollution in Changzhou. Our measurement also shows the abundance of organic nitrogen species in WSOA, and the source analyses suggest these species are likely associated with traffic emissions, which warrants more investigations on PM samples from other locations.


2008 ◽  
Vol 8 (6) ◽  
pp. 19457-19486
Author(s):  
M. Dall'Osto ◽  
R. M. Harrison ◽  
H. Coe ◽  
P. I. Williams ◽  
J. D. Allan

Abstract. Nitrate aerosols make a very major contribution to PM2.5 and PM10 in western Europe, but their sources and pathways have not been fully elucidated. An Aerosol Time-Of-Flight Mass Spectrometer (ATOFMS) and a Compact Time of Flight Aerosol Mass Spectrometer (C-ToF-AMS) were deployed in an urban background location in London, UK, collecting data as part of the REPARTEE-I experiment. During REPARTEE-I, daily PM10 concentrations ranged up to 43.6 µg m−3, with hourly nitrate concentrations (measured by AMS) of up to 5.3 µg m−3. The application of the ART-2a neural network algorithm to the ATOFMS data characterised the nitrate particles as occurring in two distinct clusters (i.e. particle types). The first (33.6% of particles by number) appeared to be locally produced in urban locations during nighttime, whilst the second (22.8% of particles by number) was regionally transported from continental Europe. Nitrate in locally produced aerosol was present mainly in particles smaller than 300 nm, whilst the regional nitrate presented a coarser mode, peaking at 600 nm. In both aerosol types, nitrate was found to be internally mixed with sulphate, ammonium, elemental and organic carbon. Nitrate in regional aerosol appeared to be more volatile than that locally formed. During daytime, a core of the regionally transported nitrate aerosol particle type composed of organic carbon and sulphate was detected.


2020 ◽  
Vol 30 (2) ◽  
Author(s):  
Rirhandzu J. Novela ◽  
Wilson M. Gitari ◽  
Hector Chikoore ◽  
Peter Molnar ◽  
Rabelani Mudzielwana ◽  
...  

This paper presents a chemical characterization of fine particulate matter in air masses passing through Thohoyandou and further determines their sources. Fine particulate matter (PM2.5) was collected and quantified using gravimetric method. X-ray fluorescence, Smoke stain reflectometer, Optical Transmissometer and Scanning Electron Microscopy- Energy Dispersive X-Ray Spectroscopy were used to determine the chemical and morphological composition of the particulate matter. The source apportionment was done using principal component analysis while the HYSPLIT model was used to depict the long-range transport clusters. The mean of concentrations of PM2.5, soot, black carbon and UVPM were 10.9 μg/m3, 0.69x10-5 m-1, 1.22 μg/m3 and 1.40 μg/m3, respectively. A total of 24 elements were detected in the PM2.5 with Pd, Sn, Sb, Mg, Al and Si being the dominant elements. SEM-EDS have shown the presence of irregular, flat and spherical particles which is associated with crustal material and industrial emissions. Source apportionment analysis revealed six major sources of PM2.5 in Thohoyandou namely, crustal materials, industrial emissions, vehicular emissions, urban emissions, fossil fuel combustion and fugitive-Pd. Air parcels that pass-through Thohoyandou were clustered into four. The major pathways were from the SW Indian Ocean, Atlantic Ocean and inland trajectories. Clusters from the ocean are associated with low concentration, while inland clusters are associated with high concentration of PM2.5. The PM2.5 occasionally exceeds the WHO daily guideline in Thohoyandou and the sources of PM2.5 extend beyond the borders. This study recommends that further studies need to be carried out to assess the health impacts of PM2.5 in Thohoyandou.


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