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Izhar S, Gupta T, Qadri AM, Panday AK. Wintertime chemical characteristics of aerosol and their role in light extinction during clear and polluted days in rural Indo Gangetic plain. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 282:117034. [PMID: 33839614 DOI: 10.1016/j.envpol.2021.117034] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 03/23/2021] [Accepted: 03/27/2021] [Indexed: 06/12/2023]
Abstract
This paper reports the chemical and light extinction characteristics of fine aerosol (PM2.5) during the winter period (2017-18) at Lumbini, Nepal, a rural site on the Indo Gangetic Plains. A modified IMPROVE algorithm was employed to reconstruct light extinction by chemical constituents of aerosol. The fine aerosol levels impacted visibility adversely during daytime, but during nighttime visibility was controlled by fog droplets rather than by aerosols. The PM2.5 chemical constituents showed varying characteristics during clear and polluted days. The average NO3-/SO42- concentration ratio was 0.57 during clear and 1.36 and polluted days, signifying a change in secondary inorganics and formation processes mainly due to decreasing photochemical production and due to increased partitioning of nitrate particles at a lower temperature. The increased secondary organics contribution and the higher OM/OC ratio (2.2) during polluted days showed the vital role of aqueous processing and biomass burning emissions in determining the concentration of organics. Total light extinction was 2.3 times higher on polluted days compared to clear days, while the PM2.5 mass concentration was 1.5 times higher. This variation in mass and extinction order signifies that various chemical components in fine particles have a more considerable impact on light extinction. On clear days we found that carbonaceous particles (OM and EC) made a major contribution to light extinction. In contrast, the extinction contribution by secondary inorganic (especially NH4NO3) increased significantly during polluted days, with hygroscopic growth and enhanced scattering efficiency at higher RH conditions playing a major role. The comparison between clear and polluted days altogether suggests that regulating the nitrate sources can help significantly in improving the visibility levels and restrict fog haze development during wintertime in rural IGP.
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Affiliation(s)
- Saifi Izhar
- Department of Civil Engineering, Indian Institute of Technology Kanpur, India; International Centre for Integrated Mountain Development (ICIMOD), Khumaltar, Lalitpur, Nepal.
| | - Tarun Gupta
- Department of Civil Engineering, Indian Institute of Technology Kanpur, India; Centre of Environmental Science and Engineering, Indian Institute of Technology Kanpur, India
| | - Adnan Mateen Qadri
- Department of Civil Engineering, Indian Institute of Technology Kanpur, India
| | - Arnico K Panday
- Ullens Education Foundation, Lalitpur, Nepal; International Centre for Integrated Mountain Development (ICIMOD), Khumaltar, Lalitpur, Nepal
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Zhou W, Xu W, Kim H, Zhang Q, Fu P, Worsnop DR, Sun Y. A review of aerosol chemistry in Asia: insights from aerosol mass spectrometer measurements. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2020; 22:1616-1653. [PMID: 32672265 DOI: 10.1039/d0em00212g] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Anthropogenic emissions in Asia have significantly increased during the last two decades; as a result, the induced air pollution and its influences on radiative forcing and public health are becoming increasingly prominent. The Aerodyne Aerosol Mass Spectrometer (AMS) has been widely deployed in Asia for real-time characterization of aerosol chemistry. In this paper, we review the AMS measurements in Asia, mainly in China, Korea, Japan, and India since 2001 and summarize the key results and findings. The mass concentrations of non-refractory submicron aerosol species (NR-PM1) showed large spatial distributions with high mass loadings occurring in India and north and northwest China (60.2-81.3 μg m-3), whereas much lower values were observed in Korea, Japan, Singapore and regional background sites (7.5-15.1 μg m-3). Aerosol composition varied largely in different regions, but was overall dominated by organic aerosols (OA, 32-75%), especially in south and southeast Asia due to the impact of biomass burning. While sulfate and nitrate showed comparable contributions in urban and suburban regions in north China, sulfate dominated inorganic aerosols in south China, Japan and regional background sites. Positive matrix factorization analysis identified multiple OA factors from different sources and processes in different atmospheric environments, e.g., biomass burning OA in south and southeast Asia and agricultural seasons in China, cooking OA in urban areas, and coal combustion in north China. However, secondary OA (SOA) was a ubiquitous and dominant aerosol component in all regions, accounting for 43-78% of OA. The formation of different SOA subtypes associated with photochemical production or aqueous-phase/fog processing was widely investigated. The roles of primary emissions, secondary production, regional transport, and meteorology on severe haze episodes, and different chemical responses of primary and secondary aerosol species to source emission changes and meteorology were also demonstrated. Finally, future prospects of AMS studies on long-term and aircraft measurements, water-soluble OA, the link of OA volatility, oxidation levels, and phase state were discussed.
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Affiliation(s)
- Wei Zhou
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, 100029 Beijing, China.
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Mandariya AK, Tripathi SN, Gupta T, Mishra G. Wintertime hygroscopic growth factors (HGFs) of accumulation mode particles and their linkage to chemical composition in a heavily polluted urban atmosphere of Kanpur at the Centre of IGP, India: Impact of ambient relative humidity. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 704:135363. [PMID: 31837851 DOI: 10.1016/j.scitotenv.2019.135363] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 10/14/2019] [Accepted: 11/01/2019] [Indexed: 06/10/2023]
Abstract
This study reported results of the wintertime simultaneous measurements of hygroscopic growth factors (HGFs) and particle-phase chemical composition of accumulation mode particles using a self-assembled Hygroscopic Tandem Differential Mobility Analyzer (H-TDMA) and an Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS), respectively at a heavily polluted urban atmosphere of Kanpur, situated in the center of IGP in India. HGFs at 85% relative humidity (RH) and the size-resolved composition of ambient aerosol particles (dry electrical mobility diameters of 100 and 150 nm) were investigated. HGF_85% was found to increase with particle size. The relative mass fraction of organic aerosol (OA) and NH4NO3 are probably the major contributors to the fluctuation of the HGF_85% for both particle sizes. The HGF_85% of accumulation mode particles were observed to increase from the minimum value observed during the morning until its maximum afternoon value. This study reported two maximum (early morning and afternoon time) and two minimum values (morning and evening time) of HGF_85%s. As a consequence, the main reasons for this incremental behavior were, increase in the ratio of inorganic to OA and oxidation level, f44 (m/z44/OA) of the OA within the particle phase. In context to the effect of ambient RH, this study reported two distinct variations of mean HGF_85% as the function of ambient RH. The positive linear relationship at low RH (LRH, RH ≤ 50%) was clearly associated with low OA loading, relatively higher substantial temperature, and wind speed. We also observed increment in f44, and effective density indicating aging of aerosol. However, HGF_85% was found to inversely decline as a function of RH at higher RH (HRH, RH > 50%) conditions, which clearly reflect the more significant contribution of primary OA and lower oxidation level of OA. Our results show the declining trend in size-resolved effective density at HRH conditions, confirming the above conclusions.
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Affiliation(s)
| | - S N Tripathi
- Department of Civil Engineering, Indian Institute of Technology, Kanpur, India; Centre for Environmental Science and Engineering, CESE, IIT Kanpur, India.
| | - Tarun Gupta
- Department of Civil Engineering, Indian Institute of Technology, Kanpur, India; Centre for Environmental Science and Engineering, CESE, IIT Kanpur, India
| | - Gaurav Mishra
- Nuclear Engineering and Technology Programme, Department of Mechanical Engineering, IIT Kanpur, India
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Chakraborty A, Mandariya AK, Chakraborti R, Gupta T, Tripathi SN. Realtime chemical characterization of post monsoon organic aerosols in a polluted urban city: Sources, composition, and comparison with other seasons. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 232:310-321. [PMID: 28974342 DOI: 10.1016/j.envpol.2017.09.079] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2017] [Revised: 08/10/2017] [Accepted: 09/25/2017] [Indexed: 06/07/2023]
Abstract
Real time chemical characterization of non-refractory submicron aerosols (NR-PM1) was carried out during post monsoon (September-October) via Aerosol Mass Spectrometer (AMS) at a polluted urban location of Kanpur, India. Organic aerosol (OA) was found to be the dominant species with 58% contribution to total NR-PM1 mass, followed by sulfate (16%). Overall, OA was highly oxidized (average O/C = 0.66) with the dominance of oxidized OAs (60% of total OA) as revealed by source apportionment. Oxidized nature of OA was also supported by very high OC/EC ratios (average = 8.2) obtained from simultaneous offline filter sampling. High and low OA loading periods have very dramatic effects on OA composition and oxidation. OA O/C ratios during lower OA loading periods were on average 30% higher than the same from high loading periods with significant changes in types and relative contribution from oxidized OAs (OOA). Comparison of OA sources and chemistry among post monsoon and other seasons revealed significant differences. Characteristics of primary OAs remain very similar, but features of OOAs showed substantial changes from one season to another. Winter had lowest OOA contribution to total OA but similar overall O/C ratios as other seasons. This reveals that processing of primary OAs, local atmospheric chemistry, and regional contributions can significantly alter OA characteristics from one season to another. This study provides interesting insights into the seasonal variations of OA sources and evolution in a very polluted and complex environment.
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Affiliation(s)
| | | | | | - Tarun Gupta
- Department of Civil Engineering, Indian Institute of Technology, Kanpur, India; Centre of Environmental Science and Engineering, CESE, IIT Kanpur, India.
| | - S N Tripathi
- Department of Civil Engineering, Indian Institute of Technology, Kanpur, India; Centre of Environmental Science and Engineering, CESE, IIT Kanpur, India.
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Chakraborty A, Rajeev P, Rajput P, Gupta T. Water soluble organic aerosols in indo gangetic plain (IGP): Insights from aerosol mass spectrometry. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 599-600:1573-1582. [PMID: 28535589 DOI: 10.1016/j.scitotenv.2017.05.142] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 04/16/2017] [Accepted: 05/16/2017] [Indexed: 06/07/2023]
Abstract
Filter samples collected during winter of 2015-16 from two polluted urban locations (Allahabad and Kanpur) residing within Indo-Gangetic plain (IGP) showed high levels of water-soluble organic aerosols (WSOA). Total organic aerosols (OA) in submicron fraction, measured at Kanpur in real time via Aerosol Mass Spectrometer also showed substantially high concentration levels. WSOA to OA contribution in Kanpur was found to be very high (around 55%) indicating significant contributions from secondary OA (SOA). On average, WSOA oxidation ratio (O/C) was found to be higher (15-20%) in Kanpur than at Allahabad. WSOA from Allahabad was found to be following a much shallower slope (-0.38) in Van Krevelen diagram (H/C vs O/C plot) than Kanpur (-0.58). These differences suggest different composition and chemistry of WSOA at these two different locations. O/C ratios of WSOA were found to be much higher (~40%) than that of OA and independent of WSOA loading. Higher OA loadings were found to be associated with less oxidized primary OAs (POA) and culminated into lower WSOA/OA ratios. The presence of organo sulfate in filter samples from both locations indicate a significant amount of aqueous processing of organics. Concentrations and characteristics of water insoluble OA (WIOA) in Kanpur revealed that although they are present in significant quantity, their oxidation levels are much (almost 3 times) lower than that of WSOA. This finding indicates that less oxidized OAs are less soluble in line with the conventional wisdom. This study provides the first insight into oxidation levels and evolution of WSOA from India and also explores the interplay between WSOA and OA characteristics based on AMS measurements.
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Affiliation(s)
| | - Pradhi Rajeev
- Department of Civil Engineering, Indian Institute of Technology Kanpur, India
| | - Prashant Rajput
- Department of Civil Engineering, Indian Institute of Technology Kanpur, India
| | - Tarun Gupta
- Department of Civil Engineering, Indian Institute of Technology Kanpur, India; Centre for Environmental Science and Engineering, Indian Institute of Technology Kanpur, India.
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Satish R, Shamjad P, Thamban N, Tripathi S, Rastogi N. Temporal Characteristics of Brown Carbon over the Central Indo-Gangetic Plain. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:6765-6772. [PMID: 28520413 DOI: 10.1021/acs.est.7b00734] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Recent global models estimate that light absorption by brown carbon (BrC) in several regions of the world is ∼30-70% of that due to black carbon (BC). It is, therefore, important to understand its sources and characteristics on temporal and spatial scales. In this study, we conducted semicontinuous measurements of water-soluble organic carbon (WSOC) and BrC using particle-into-liquid sampler coupled with a liquid waveguide capillary cell and total organic carbon analyzer (PILS-LWCC-TOC) over Kanpur (26.5°N, 80.3°E, 142 m amsl) during a winter season (December 2015 to February 2016). In addition, mass concentrations of organic and inorganic aerosol and BC were also measured. Diurnal variability in the absorption coefficient of BrC at 365 nm (babs_365) showed higher values (35 ± 21 Mm-1) during late evening to early morning hours and was attributed to primary emissions from biomass burning (BB) and fossil fuel burning (FFB). The babs_365 reduced by more than 80% as the day progressed, which was ascribed to photo bleaching/volatilization of BrC and/or due to rising boundary layer height. Further, diurnal variability in the ratios of babs_405/babs_365 and babs_420/babs_365 suggests that the BrC composition was not uniform throughout a day. WSOC exhibited a strong correlation with babs_365 (slope = 1.22 ± 0.007, r2 = 0.70, n = 13 265, intercept = -0.69 ± 0.17), suggesting the presence of a significant but variable fraction of chromophores. Mass absorption efficiency (MAE) values of WSOC ranged from 0.003 to 5.26 m2 g-1 (1.16 ± 0.60) during the study period. Moderate correlation (r2 = 0.50, slope = 1.58 ± 0.019, n = 6471) of babs_365 was observed with the semivolatile oxygenated organic aerosols (SV-OOA) fraction of BB resolved from positive matrix factorization (PMF) analysis of organic mass spectral data obtained from a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). The low-volatility OOA (LV-OOA) fraction of BB had a similar correlation to babs_365 (r2 = 0.54, slope = 0.38 ± 0.004, n = 6471) but appears to have a smaller contribution to the absorption.
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Affiliation(s)
- Rangu Satish
- Geosciences Division, Physical Research Laboratory , Ahmedabad 380009, India
| | - Puthukkadan Shamjad
- Department of Civil Engineering and Centre for Environmental Science and Engineering, Indian Institute of Technology-Kanpur , Kanpur 208016, India
| | - Navaneeth Thamban
- Department of Civil Engineering and Centre for Environmental Science and Engineering, Indian Institute of Technology-Kanpur , Kanpur 208016, India
| | - Sachchida Tripathi
- Department of Civil Engineering and Centre for Environmental Science and Engineering, Indian Institute of Technology-Kanpur , Kanpur 208016, India
| | - Neeraj Rastogi
- Geosciences Division, Physical Research Laboratory , Ahmedabad 380009, India
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