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Cui Y, Chen K, Zhang H, Lin YH, Bahreini R. Chemical Composition and Optical Properties of Secondary Organic Aerosol from Photooxidation of Volatile Organic Compound Mixtures. ACS ES&T AIR 2024; 1:247-258. [PMID: 38633205 PMCID: PMC11019549 DOI: 10.1021/acsestair.3c00041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 02/14/2024] [Accepted: 02/14/2024] [Indexed: 04/19/2024]
Abstract
The chemical and optical properties of secondary organic aerosols (SOA) have been widely studied through environmental chamber experiments, and some of the results have been parametrized in atmospheric models to help understand their radiative effects and climate influence. While most chamber studies investigate the aerosol formed from a single volatile organic compound (VOC), the potential interactions between reactive intermediates derived from VOC mixtures are not well understood. In this study, we investigated the SOA formed from pure and mixtures of anthropogenic (phenol and 1-methylnaphthalene) and/or biogenic (longifolene) VOCs using continuous-flow, high-NOx photooxidation chamber experiments to better mimic ambient conditions. SOA optical properties, including single scattering albedo (SSA), mass absorption coefficient (MAC), and refractive index (RI) at 375 nm, and chemical composition, including the formation of oxygenated organic compounds, organic-nitrogen compounds (including organonitrates and nitro-organics), and the molecular structure of the major chromophores, were explored. Additionally, the imaginary refractive index values of SOA in the multi-VOC system were predicted using a linear-combination assumption and compared with the measured values. When two VOCs were oxidized simultaneously, we found evidence for changes in SOA chemical composition compared to SOA formed from single-VOC systems, and this change led to nonlinear effects on SOA optical properties. The nonlinear effects were found to vary between different systems.
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Affiliation(s)
- Yumeng Cui
- Department
of Environmental Sciences, University of
California, Riverside, Riverside, California 92521, United States
| | - Kunpeng Chen
- Department
of Environmental Sciences, University of
California, Riverside, Riverside, California 92521, United States
| | - Haofei Zhang
- Department
of Chemistry, University of California,
Riverside, Riverside, California 92521, United States
| | - Ying-Hsuan Lin
- Department
of Environmental Sciences, University of
California, Riverside, Riverside, California 92521, United States
| | - Roya Bahreini
- Department
of Environmental Sciences, University of
California, Riverside, Riverside, California 92521, United States
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2
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Lan Y, Zhou L, Liu S, Wan R, Wang N, Chen D, Li Y, Jiang Y, Rao Z, Jiang W, Song D, Tan Q, Yang F. Light absorption enhancement of black carbon and its impact factors during winter in a megacity of the Sichuan Basin, China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 918:170374. [PMID: 38307267 DOI: 10.1016/j.scitotenv.2024.170374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Revised: 01/07/2024] [Accepted: 01/21/2024] [Indexed: 02/04/2024]
Abstract
Carbonaceous aerosols play a vital role in global climate patterns due to their potent light absorption capabilities. However, the light absorption enhancement effect (Eabs) of black carbon (BC) is still subject to great uncertainties due to factors such as the mixing state, coating material, and particle size distribution. In this study, fine particulate matter (PM2.5) samples were collected in Chengdu, a megacity in the Sichuan Basin, during the winter of 2020 and 2021. The chemical components of PM2.5 and the light absorption properties of BC were investigated. The results revealed that secondary inorganic aerosols and carbonaceous aerosols were the dominant components in PM2.5. Additionally, the aerosol filter filtration-dissolution (AFD) treatment could improve the accuracy of measuring elemental carbon (EC) through thermal/optical analysis. During winter in Chengdu, the absorption enhancement values of BC ranged between 1.56 and 2.27, depending on the absorption wavelength and the mixing state of BC and non-BC materials. The presence of internally mixed BC and non-BC materials significantly contributed to Eabs, accounting for an average of 68 % at 405 nm and 100 % at 635 nm. The thickness of the BC coating influenced Eabs, displaying an increasing-then-decreasing trend. This trend was primarily attributed to the hygroscopic growth and dehydration shrinkage of particulate matter. Nitrate, as the major component of BC coating, played a crucial role in the lensing effect and exhibited fast growth during variation in Eabs. By combining the results from PMF, we identified the secondary formation and vehicle emission as the primary contributors to Eabs. Consequently, this study can provide valuable insights into the optical parameters, which are essential for assessing the environmental quality, improving regional atmospheric conditions, and formulating effective air pollution control strategies.
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Affiliation(s)
- Yuting Lan
- College of Architecture and Environment, Sichuan University, Chengdu 610065, China; College of Carbon Neutrality Future Technology, Sichuan University, Chengdu 610065, China; Sichuan University Yibin Park, Yibin Institute of Industrial Technology, Yibin 644600, China
| | - Li Zhou
- College of Architecture and Environment, Sichuan University, Chengdu 610065, China; College of Carbon Neutrality Future Technology, Sichuan University, Chengdu 610065, China; Sichuan University Yibin Park, Yibin Institute of Industrial Technology, Yibin 644600, China.
| | - Song Liu
- College of Architecture and Environment, Sichuan University, Chengdu 610065, China; College of Carbon Neutrality Future Technology, Sichuan University, Chengdu 610065, China; Sichuan University Yibin Park, Yibin Institute of Industrial Technology, Yibin 644600, China
| | - Ruilin Wan
- College of Architecture and Environment, Sichuan University, Chengdu 610065, China; College of Carbon Neutrality Future Technology, Sichuan University, Chengdu 610065, China; Sichuan University Yibin Park, Yibin Institute of Industrial Technology, Yibin 644600, China
| | - Ning Wang
- College of Architecture and Environment, Sichuan University, Chengdu 610065, China; College of Carbon Neutrality Future Technology, Sichuan University, Chengdu 610065, China; Sichuan University Yibin Park, Yibin Institute of Industrial Technology, Yibin 644600, China
| | - Dongyang Chen
- College of Architecture and Environment, Sichuan University, Chengdu 610065, China; College of Carbon Neutrality Future Technology, Sichuan University, Chengdu 610065, China; Sichuan University Yibin Park, Yibin Institute of Industrial Technology, Yibin 644600, China
| | - Yi Li
- College of Architecture and Environment, Sichuan University, Chengdu 610065, China; College of Carbon Neutrality Future Technology, Sichuan University, Chengdu 610065, China; Sichuan University Yibin Park, Yibin Institute of Industrial Technology, Yibin 644600, China
| | - Yan Jiang
- Sichuan Ecological Environment Monitoring Center, Chengdu 610091, China
| | - Zhihan Rao
- College of Architecture and Environment, Sichuan University, Chengdu 610065, China; College of Carbon Neutrality Future Technology, Sichuan University, Chengdu 610065, China; Sichuan University Yibin Park, Yibin Institute of Industrial Technology, Yibin 644600, China; Sichuan Ecological Environment Monitoring Center, Chengdu 610091, China
| | - Wanting Jiang
- Chengdu Academy of Environmental Sciences, Chengdu 610072, China
| | - Danlin Song
- Chengdu Academy of Environmental Sciences, Chengdu 610072, China
| | - Qinwen Tan
- Chengdu Academy of Environmental Sciences, Chengdu 610072, China
| | - Fumo Yang
- College of Architecture and Environment, Sichuan University, Chengdu 610065, China; College of Carbon Neutrality Future Technology, Sichuan University, Chengdu 610065, China; Sichuan University Yibin Park, Yibin Institute of Industrial Technology, Yibin 644600, China
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3
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Zhang Z, Cheng Y, Liang L, Liu J. The Measurement of Atmospheric Black Carbon: A Review. TOXICS 2023; 11:975. [PMID: 38133376 PMCID: PMC10748019 DOI: 10.3390/toxics11120975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 11/16/2023] [Accepted: 11/28/2023] [Indexed: 12/23/2023]
Abstract
Black Carbon (BC), the second-largest contributor to global warming, has detrimental effects on human health and the environment. However, the accurate quantification of BC poses a significant challenge, impeding the comprehensive assessment of its impacts. Therefore, this paper aims to critically review three quantitative methods for measuring BC: Thermal Optical Analysis (TOA), the Optical Method, and Laser-Induced Incandescence (LII). The determination principles, available commercial instruments, sources of deviation, and correction approaches associated with these techniques are systematically discussed. By synthesizing and comparing the quantitative results reported in previous studies, this paper aims to elucidate the underlying relationships and fundamental disparities among Elemental Carbon (EC), Equivalent Black Carbon (eBC), and Refractory Black Carbon (rBC). Finally, based on the current advancements in BC quantification, recommendations are proposed to guide future research directions.
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Affiliation(s)
- Zhiqing Zhang
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China; (Z.Z.); (Y.C.)
| | - Yuan Cheng
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China; (Z.Z.); (Y.C.)
| | - Linlin Liang
- State Key Laboratory of Severe Weather & Key Laboratory for Atmospheric Chemistry, Chinese Academy of Meteorological Sciences, Beijing 100081, China
| | - Jiumeng Liu
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China; (Z.Z.); (Y.C.)
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4
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Sun J, Xie C, Xu W, Chen C, Ma N, Xu W, Lei L, Li Z, He Y, Qiu Y, Wang Q, Pan X, Su H, Cheng Y, Wu C, Fu P, Wang Z, Sun Y. Light absorption of black carbon and brown carbon in winter in North China Plain: comparisons between urban and rural sites. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 770:144821. [PMID: 33736402 DOI: 10.1016/j.scitotenv.2020.144821] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 12/20/2020] [Accepted: 12/23/2020] [Indexed: 05/19/2023]
Abstract
The light absorption black carbon (BC) and brown carbon (BrC) are two important sources of uncertainties in radiative forcing estimate. Here we investigated the light absorption enhancement (Eabs) of BC due to coated materials at an urban (Beijing) and a rural site (Gucheng) in North China Plain (NCP) in winter 2019 by using a photoacoustic extinctiometer coupled with a thermodenuder. Our results showed that the average (±1σ) Eabs was 1.32 (±0.15) at the rural site, which was slightly higher than that at the urban site (1.24 ± 0.15). The dependence of Eabs on coating materials was found to be relatively limited at both sites. However, Eabs presented considerable increases as a function of relative humidity below 70%. Further analysis showed that Eabs during non-heating period in Beijing was mainly caused by secondary components, while it was dominantly contributed by enhanced primary emissions in heating season at both sites. In particular, aerosol particles mixed with coal combustion emissions had a large impact on Eabs (>1.40), while the fresh traffic emissions and freshly oxidized secondary OA (SOA) had limited Eabs (1.00-1.23). Although highly aged or aqueous-phase processed SOA coated on BC showed the largest Eabs, their contributions to the bulk absorption enhancement were generally small. We also quantified the absorption of BrC and source contributions. The results showed the BrC absorption at the rural site was nearly twice that of urban site, yet absorption Ångström exponents were similar. Multiple linear regression analysis highlighted the major sources of BrC being coal combustion emissions and photochemical SOA at both sites with additional biomass burning at the rural site. Overall, our results demonstrated the relatively limited winter light absorption enhancement of BC in different chemical environments in NCP, which needs be considered in regional climate models to improve BC radiative forcing estimates.
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Affiliation(s)
- Jiaxing Sun
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China; College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Conghui Xie
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China; College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Weiqi Xu
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
| | - Chun Chen
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China; College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Nan Ma
- Institute for Environmental and Climate Research, Jinan University, Guangzhou 511443, China
| | - Wanyun Xu
- State Key Laboratory of Severe Weather & Key Laboratory for Atmospheric Chemistry, Institute of Atmospheric Composition, Chinese Academy of Meteorological Sciences, Beijing 100081, China
| | - Lu Lei
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China; College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhijie Li
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China; College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yao He
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China; College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yanmei Qiu
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China; College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qingqing Wang
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
| | - Xiaole Pan
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
| | - Hang Su
- Multiphase Chemistry Department, Max Planck Institute for Chemistry, Mainz 55128, Germany
| | - Yafang Cheng
- Minerva Research Group, Max Planck Institute for Chemistry, Mainz 55128, Germany
| | - Cheng Wu
- Institute of Mass Spectrometer and Atmospheric Environment, Jinan University, Guangzhou, China
| | - Pingqing Fu
- Institute of Surface-Earth System Science, Tianjin University, Tianjin 300072, China
| | - Zifa Wang
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China; College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China; Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China
| | - Yele Sun
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China; College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China; Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
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5
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Kong X, Salvador CM, Carlsson S, Pathak R, Davidsson KO, Le Breton M, Gaita SM, Mitra K, Hallquist ÅM, Hallquist M, Pettersson JBC. Molecular characterization and optical properties of primary emissions from a residential wood burning boiler. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 754:142143. [PMID: 32898781 DOI: 10.1016/j.scitotenv.2020.142143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 08/25/2020] [Accepted: 08/31/2020] [Indexed: 06/11/2023]
Abstract
Modern small-scale biomass burners have been recognized as an important renewable energy source because of the economic and environmental advantages of biomass over fossil fuels. However, the characteristics of their gas and particulate emissions remain incompletely understood, and there is substantial uncertainty concerning their health and climate impacts. Here, we present online measurements conducted during the operation of a residential wood-burning boiler. The measured parameters include gas and particle concentrations, optical absorption and chemical characteristics of gases and particles. Positive matrix factorization was performed to analyze data from a high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) equipped with a filter inlet for gases and aerosols (FIGAERO). Six factors were identified and interpreted. Three factors were related to the chemical composition of the fuel representing lignin pyrolysis products, cellulose/hemicellulose pyrolysis products, and nitrogen-containing organics, while three factor were related to the physical characteristics of the emitted compounds: volatile compounds, semi-volatile compounds, and filter-derived compounds. An ordinal analysis was performed based on the factor fractions to identify the most influential masses in each factor, and by deconvoluting high-resolution mass spectra fingerprint molecules for each factor were identified. Results from the factor analysis were linked to the optical properties of the emissions, and lignin and cellulose/hemicellulose pyrolysis products appeared to be the most important sources of brown carbon under the tested burning conditions. It is concluded that the emissions from the complex combustion process can be described by a limited set of physically meaningful factors, which will help to rationalize subsequent transformation and tracing of emissions in the atmosphere and associated impacts on health and climate.
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Affiliation(s)
- Xiangrui Kong
- Department of Chemistry and Molecular Biology, Atmospheric Science, University of Gothenburg, SE-412 96 Gothenburg, Sweden.
| | - Christian Mark Salvador
- Department of Chemistry and Molecular Biology, Atmospheric Science, University of Gothenburg, SE-412 96 Gothenburg, Sweden
| | | | - Ravikant Pathak
- Department of Chemistry and Molecular Biology, Atmospheric Science, University of Gothenburg, SE-412 96 Gothenburg, Sweden
| | | | - Michael Le Breton
- Department of Chemistry and Molecular Biology, Atmospheric Science, University of Gothenburg, SE-412 96 Gothenburg, Sweden
| | - Samuel Mwaniki Gaita
- Department of Chemistry and Molecular Biology, Atmospheric Science, University of Gothenburg, SE-412 96 Gothenburg, Sweden
| | - Kalyan Mitra
- Department of Chemistry and Molecular Biology, Atmospheric Science, University of Gothenburg, SE-412 96 Gothenburg, Sweden
| | - Åsa M Hallquist
- IVL Swedish Environmental Research Institute, Gothenburg, Sweden
| | - Mattias Hallquist
- Department of Chemistry and Molecular Biology, Atmospheric Science, University of Gothenburg, SE-412 96 Gothenburg, Sweden
| | - Jan B C Pettersson
- Department of Chemistry and Molecular Biology, Atmospheric Science, University of Gothenburg, SE-412 96 Gothenburg, Sweden.
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6
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June N, Wang X, Chen LWA, Chow JC, Watson JG, Wang X, Henderson BH, Zheng Y, Mao J. Spatial and temporal variability of brown carbon in United States: implications for direct radiative effects. GEOPHYSICAL RESEARCH LETTERS 2020; 47:10.1029/2020gl090332. [PMID: 34381286 PMCID: PMC8353956 DOI: 10.1029/2020gl090332] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 10/28/2020] [Indexed: 06/12/2023]
Abstract
A newly developed dataset from the Interagency Monitoring of PROtected Visual Environments (IMPROVE) observation network, combined with a 3-D chemical transport model, is used to evaluate the spatial and temporal variability of brown carbon (BrC) in the United States. The model with BrC emitted from biomass burning and biofuel emissions agrees with the seasonal and spatial variability of BrC planetary boundary layer (PBL) absorption aerosol optical depth (AAOD) observations within a factor of 2. The model without whitening, the tendency for absorption to decrease with aerosol aging, overestimates the observed BrC PBL AAOD, and does not reflect the measured BrC PBL AAOD spatial variability. The model shows higher absorption direct radiative effects (DRE) from BrC at northern high latitudes than at mid-latitudes in spring and summer, due to boreal fire emissions, long whitening lifetimes and high surface albedos. These findings highlight the need to study BrC over the Arctic region.
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Affiliation(s)
- Nicole June
- Department of Chemistry and Biochemistry and Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK, USA
| | - Xuan Wang
- School of Energy and Environment, City University of Hong Kong, Hong Kong SAR, China
| | - L.-W. Antony Chen
- Department of Environmental and Operational Health, University of Nevada, Las Vegas, NV, USA
| | - Judith C. Chow
- Division of Atmospheric Sciences, Desert Research Institute, Reno, NV, USA
| | - John G. Watson
- Division of Atmospheric Sciences, Desert Research Institute, Reno, NV, USA
| | - Xiaoliang Wang
- Division of Atmospheric Sciences, Desert Research Institute, Reno, NV, USA
| | - Barron H. Henderson
- Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
| | - Yiqi Zheng
- Department of Chemistry and Biochemistry and Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK, USA
| | - Jingqiu Mao
- Department of Chemistry and Biochemistry and Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK, USA
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7
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Soleimanian E, Mousavi A, Taghvaee S, Shafer MM, Sioutas C. Impact of secondary and primary particulate matter (PM) sources on the enhanced light absorption by brown carbon (BrC) particles in central Los Angeles. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 705:135902. [PMID: 31837867 DOI: 10.1016/j.scitotenv.2019.135902] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 11/15/2019] [Accepted: 12/01/2019] [Indexed: 05/23/2023]
Abstract
In this study, we investigated aerosol chemical composition, spectral properties of aerosol extracts, and source contributions to the aerosol light-absorbing brown carbon (BrC) in central Los Angeles from July 2018 to March 2019, during warm and cold seasons. Spectrophotometric measurements (water and methanol extracts; 200 < λ < 1100) and chemical analyses were performed on collected particulate matter (PM), and relationships of BrC light absorption (Abs365) to source tracer chemical species were evaluated. Mass absorption efficiency (MAE) of both water and methanol extracted solutions exhibited an increasing trend from warm period to cold season, with an annual average value of 0.61 ± 0.22 m2.g-1 and 1.38 ± 0.89 m2.g-1, respectively. Principal component analysis (PCA) were coupled with multiple linear regression (MLR) to identify and quantify sources of BrC light absorption in each of the seasons. Our finding documented fossil fuel combustion as the dominant source of BrC light absorption during warm season, with relative contribution of 38% to total BrC light absorption, followed by (secondary organic aerosol) SOA (30%) and biomass burning (12%). In contrast, biomass burning was the major source of BrC during the cold season (53%), while fossil fuel combustion and SOA contributed to 18% and 12% of BrC, respectively. Significantly higher contribution of biomass burning to BrC during the cold season suggested that residential heating activities (wood burning) play a major role in increased BrC concentrations. Previously collected Aethalometer model data documented fossil fuel combustion as the dominant contributing source to >90% of BC throughout the year. Finally, the solar radiation absorption ratio of BrC to elemental carbon (EC) in the ultraviolet range (300-400 nm) was maximum during the cold season with the annual corresponding values of 13-25% and 17-29% for water- and methanol-soluble BrC, respectively; which provides further evidence of the important effect of BrC light absorption on atmospheric radiative balance.
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Affiliation(s)
- Ehsan Soleimanian
- University of Southern California, Department of Civil and Environmental Engineering, Los Angeles, CA, USA.
| | - Amirhosein Mousavi
- University of Southern California, Department of Civil and Environmental Engineering, Los Angeles, CA, USA.
| | - Sina Taghvaee
- University of Southern California, Department of Civil and Environmental Engineering, Los Angeles, CA, USA.
| | - Martin M Shafer
- University of Wisconsin-Madison, Wisconsin State Laboratory of Hygiene, Madison, WI, USA.
| | - Constantinos Sioutas
- University of Southern California, Department of Civil and Environmental Engineering, Los Angeles, CA, USA.
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8
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Huang M, Ivey C, Hu Y, Holmes HA, Strickland MJ. Source apportionment of primary and secondary PM 2.5: Associations with pediatric respiratory disease emergency department visits in the U.S. State of Georgia. ENVIRONMENT INTERNATIONAL 2019; 133:105167. [PMID: 31634664 DOI: 10.1016/j.envint.2019.105167] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 09/03/2019] [Accepted: 09/06/2019] [Indexed: 06/10/2023]
Abstract
We developed a hybrid chemical transport model and receptor model (CTM-RM) to conduct source apportionment of both primary and secondary PM2.5 (particulate matter ≤2.5 μm in diameter) at 36 km resolution throughout the U.S. State of Georgia for the years 2005 and 2007. This novel source apportionment model enabled us to estimate and compare associations of short-term changes in 12 PM2.5 source concentrations (agriculture, biogenic, coal, dust, fuel oil, metals, natural gas, non-road mobile diesel, non-road mobile gasoline, on-road mobile diesel, on-road mobile gasoline, and all other sources) with emergency department (ED) visits for pediatric respiratory diseases. ED visits for asthma (N = 49,651), pneumonia (N = 25,558), and acute upper respiratory infections (acute URI, N = 235,343) among patients aged ≤18 years were obtained from patient claims records. Using a case-crossover study, we estimated odds ratios per interquartile range (IQR) increase for 3-day moving average PM2.5 source concentrations using conditional logistic regression, matching on day-of-week, month, and year, and adjusting for average temperature, humidity, and holidays. We fit both single-source and multi-source models. We observed positive associations between several PM2.5 sources and ED visits for asthma, pneumonia, and acute URI. For example, for asthma, per IQR increase in the source contribution in the single-source model, odds ratios were 1.022 (95% CI: 1.013, 1.031) for dust; 1.050 (95% CI: 1.036, 1.063) for metals, and 1.091 (95% CI: 1.064, 1.119) for natural gas. These sources comprised 5.7%, 2.2%, and 6.3% of total PM2.5 mass, respectively. PM2.5 from metals and natural gas were positively associated with all three respiratory outcomes. In addition, non-road mobile diesel was positively associated with pneumonia and acute URI.
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Affiliation(s)
- Mengjiao Huang
- School of Community Health Sciences, University of Nevada, Reno, NV, USA.
| | - Cesunica Ivey
- Department of Chemical and Environmental Engineering, University of California, Riverside, CA, USA.
| | - Yongtao Hu
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA, USA.
| | - Heather A Holmes
- Atmospheric Sciences Program, Department of Physics, University of Nevada, Reno, NV, USA.
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9
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Xie M, Chen X, Holder AL, Hays MD, Lewandowski M, Offenberg JH, Kleindienst TE, Jaoui M, Hannigan MP. Light absorption of organic carbon and its sources at a southeastern U.S. location in summer. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 244:38-46. [PMID: 30321710 PMCID: PMC6697000 DOI: 10.1016/j.envpol.2018.09.125] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 09/24/2018] [Accepted: 09/25/2018] [Indexed: 05/28/2023]
Abstract
Light-absorbing organic carbon (OC), also referred to as "brown carbon" (BrC), has been intensively investigated in atmospheres impacted by biomass burning. However, other BrC sources (e.g., secondary formation in the atmosphere) are rarely studied in ambient aerosols. In the current work, forty-five PM2.5 filter samples were collected in Research Triangle Park (RTP), NC, USA from June 1st to July 15th, 2013. The bulk carbonaceous components, including OC, elemental carbon (EC), water soluble OC (WSOC), and an array of organic molecular markers were measured; an ultraviolet/visible spectrometer was used to measure the light absorption of methanol extractable OC and WSOC. The average light absorption per OC and WSOC mass of PM2.5 samples in summer RTP are 0.36 ± 0.16 m2 gC-1 and 0.29 ± 0.13 m2 gC-1, respectively, lower than the ambient aerosol samples impacted by biomass burning and/or fossil fuel combustion (0.7-1.6 m2 gC-1) from other places. Less than 1% of the aqueous extracts absorption is attributed to the light-absorbing chromophores (nitroaromatic compounds) identified in this work. To identify the major sources of BrC absorption in RTP in the summer, Positive Matrix Factorization (PMF) was applied to a dataset containing optical properties and chemical compositions of carbonaceous components in PM2.5. The results suggest that the formation of biogenic secondary organic aerosol (SOA) containing organosulfates is an important BrC source, contributing up to half of the BrC absorption in RTP during the summertime.
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Affiliation(s)
- Mingjie Xie
- Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, School of Environmental Science and Engineering, Nanjing University of Information Science & Technology, 219 Ningliu Road, Nanjing, 210044, China; State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, China; Oak Ridge Institute for Science and Education (ORISE), Office of Research and Development, U.S. Environmental Protection Agency, 109 T.W. Alexander Drive, Research Triangle Park, NC, 27711, USA; National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 109 T.W. Alexander Drive, Research Triangle Park, NC, 27711, USA.
| | - Xi Chen
- National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 109 T.W. Alexander Drive, Research Triangle Park, NC, 27711, USA
| | - Amara L Holder
- National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 109 T.W. Alexander Drive, Research Triangle Park, NC, 27711, USA
| | - Michael D Hays
- National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 109 T.W. Alexander Drive, Research Triangle Park, NC, 27711, USA
| | - Michael Lewandowski
- National Exposure Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 109 T.W. Alexander Drive, Research Triangle Park, NC, 27711, USA
| | - John H Offenberg
- National Exposure Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 109 T.W. Alexander Drive, Research Triangle Park, NC, 27711, USA
| | - Tadeusz E Kleindienst
- National Exposure Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 109 T.W. Alexander Drive, Research Triangle Park, NC, 27711, USA
| | - Mohammed Jaoui
- National Exposure Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 109 T.W. Alexander Drive, Research Triangle Park, NC, 27711, USA
| | - Michael P Hannigan
- Department of Mechanical Engineering, University of Colorado, Boulder, CO, 80309, USA
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10
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Xie M, Shen G, Holder AL, Hays MD, Jetter JJ. Light absorption of organic carbon emitted from burning wood, charcoal, and kerosene in household cookstoves. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 240:60-67. [PMID: 29729570 PMCID: PMC6715134 DOI: 10.1016/j.envpol.2018.04.085] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 03/25/2018] [Accepted: 04/19/2018] [Indexed: 06/08/2023]
Abstract
Household cookstove emissions are an important source of carbonaceous aerosols globally. The light-absorbing organic carbon (OC), also termed brown carbon (BrC), from cookstove emissions can impact the Earth's radiative balance, but is rarely investigated. In this work, PM2.5 filter samples were collected during combustion experiments with red oak wood, charcoal, and kerosene in a variety of cookstoves mainly at two water boiling test phases (cold start CS, hot start HS). Samples were extracted in methanol and extracts were examined using spectrophotometry. The mass absorption coefficients (MACλ, m2 g-1) at five wavelengths (365, 400, 450, 500, and 550 nm) were mostly inter-correlated and were used as a measurement proxy for BrC. The MAC365 for red oak combustion during the CS phase correlated strongly to the elemental carbon (EC)/OC mass ratio, indicating a dependency of BrC absorption on burn conditions. The emissions from cookstoves burning red oak have an average MACλ 2-6 times greater than those burning charcoal and kerosene, and around 3-4 times greater than that from biomass burning measured in previous studies. These results suggest that residential cookstove emissions could contribute largely to ambient BrC, and the simulation of BrC radiative forcing in climate models for biofuel combustion in cookstoves should be treated specifically and separated from open biomass burning.
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Affiliation(s)
- Mingjie Xie
- Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, School of Environmental Science and Engineering, Nanjing University of Information Science & Technology, 219 Ningliu Road, Nanjing, 210044, China; State Key Laboratory of Pollution Control and Resource Reuse, Nanjing University, Nanjing, 210023, China; Oak Ridge Institute for Science and Education (ORISE), Office of Research and Development, U.S. Environmental Protection Agency, 109 T.W. Alexander Drive, Research Triangle Park, NC 27711, USA; National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 109 T.W. Alexander Drive, Research Triangle Park, NC 27711, USA.
| | - Guofeng Shen
- Oak Ridge Institute for Science and Education (ORISE), Office of Research and Development, U.S. Environmental Protection Agency, 109 T.W. Alexander Drive, Research Triangle Park, NC 27711, USA; National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 109 T.W. Alexander Drive, Research Triangle Park, NC 27711, USA
| | - Amara L Holder
- National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 109 T.W. Alexander Drive, Research Triangle Park, NC 27711, USA
| | - Michael D Hays
- National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 109 T.W. Alexander Drive, Research Triangle Park, NC 27711, USA
| | - James J Jetter
- National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 109 T.W. Alexander Drive, Research Triangle Park, NC 27711, USA
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11
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Kelly JT, Parworth CL, Zhang Q, Miller DJ, Sun K, Zondlo MA, Baker KR, Wisthaler A, Nowak JB, Pusede SE, Cohen RC, Weinheimer AJ, Beyersdorf AJ, Tonnesen GS, Bash JO, Valin LC, Crawford JH, Fried A, Walega JG. Modeling NH 4NO 3 Over the San Joaquin Valley During the 2013 DISCOVER-AQ Campaign. JOURNAL OF GEOPHYSICAL RESEARCH. ATMOSPHERES : JGR 2018; 123:4727-4745. [PMID: 30245954 PMCID: PMC6145493 DOI: 10.1029/2018jd028290] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Accepted: 04/12/2018] [Indexed: 05/06/2023]
Abstract
The San Joaquin Valley (SJV) of California experiences high concentrations of particulate matter NH4NO3 during episodes of meteorological stagnation in winter. A rich data set of observations related to NH4NO3 formation was acquired during multiple periods of elevated NH4NO3 during the Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) field campaign in SJV in January and February 2013. Here NH4NO3 is simulated during the SJV DISCOVER-AQ study period with the Community Multiscale Air Quality (CMAQ) model, diagnostic model evaluation is performed using the DISCOVER-AQ data set, and integrated reaction rate analysis is used to quantify HNO3 production rates. Simulated NO3- generally agrees well with routine monitoring of 24-hr average NO3-, but comparisons with hourly average NO3- measurements in Fresno revealed differences at higher time resolution. Predictions of gas-particle partitioning of total nitrate (HNO3 + NO3-) and NHx (NH3 + NH4+) generally agree well with measurements in Fresno, although partitioning of total nitrate to HNO3 is sometimes overestimated at low relative humidity in afternoon. Gas-particle partitioning results indicate that NH4NO3 formation is limited by HNO3 availability in both the model and ambient. NH3 mixing ratios are underestimated, particularly in areas with large agricultural activity, and additional work on the spatial allocation of NH3 emissions is warranted. During a period of elevated NH4NO3, the model predicted that the OH + NO2 pathway contributed 46% to total HNO3production in SJV and the N2O5 heterogeneous hydrolysis pathway contributed 54%. The relative importance of the OH + NO2 pathway for HNO3 production is predicted to increase as NOx emissions decrease.
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Affiliation(s)
- James T Kelly
- Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency, RTP, NC, USA
| | - Caroline L Parworth
- Ames Research Center, National Aeronautics and Space Administration, Moffett Field, CA, USA
| | - Qi Zhang
- Department of Environmental Toxicology, University of California, Davis, CA, USA
- Agricultural and Environmental Chemistry Graduate Group, University of California, Davis, CA, USA
| | | | - Kang Sun
- Atomic and Molecular Physics Division, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, USA
| | - Mark A Zondlo
- Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ, USA
| | - Kirk R Baker
- Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency, RTP, NC, USA
| | - Armin Wisthaler
- Institute for Ion Physics and Applied Physics, University of Innsbruck, Innsbruck, Austria
| | - John B Nowak
- Langley Research Center, National Aeronautics and Space Administration, Hampton, VA, USA
| | - Sally E Pusede
- Department of Environmental Sciences, University of Virginia, Charlottesville, VA, USA
| | - Ronald C Cohen
- Department of Earth and Planetary Sciences, University of California at Berkeley, Berkeley, CA, USA
| | | | - Andreas J Beyersdorf
- Department of Chemistry and Biochemistry, California State University, San Bernardino, CA, USA
| | - Gail S Tonnesen
- Region 8, U.S. Environmental Protection Agency, Denver, CO, USA
| | - Jesse O Bash
- Office of Research and Development, U.S. Environmental Protection Agency, RTP, NC, USA
| | - Luke C Valin
- Office of Research and Development, U.S. Environmental Protection Agency, RTP, NC, USA
| | - James H Crawford
- Langley Research Center, National Aeronautics and Space Administration, Hampton, VA, USA
| | - Alan Fried
- Institute of Arctic and Alpine Research, University of Colorado Boulder, Boulder, CO, USA
| | - James G Walega
- Institute of Arctic and Alpine Research, University of Colorado Boulder, Boulder, CO, USA
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12
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Prabhakar G, Parworth C, Zhang X, Kim H, Young D, Beyersdorf AJ, Ziemba LD, Nowak JB, Bertram TH, Faloona IC, Zhang Q, Cappa CD. Observational assessment of the role of nocturnal residual-layer chemistry in determining daytime surface particulate nitrate concentrations. ATMOSPHERIC CHEMISTRY AND PHYSICS 2017; 17:14747-14770. [PMID: 32704248 PMCID: PMC7376613 DOI: 10.5194/acp-17-14747-2017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
This study discusses an analysis of combined airborne and ground observations of particulate nitrate (NO3 - (p)) concentrations made during the wintertime DISCOVER-AQ study at one of the most polluted cities in the United States, Fresno, CA in the San Joaquin Valley (SJV) and focuses on development of understanding of the various processes that impact surface nitrate concentrations during pollution events. The results provide an explicit case-study illustration of how nighttime chemistry can influence daytime surface-level NO3 - (p) concentrations, complementing previous studies in the SJV. The observations exemplify the critical role that nocturnal chemical production of NO3 - (p) aloft in the residual layer (RL) can play in determining daytime surface-level NO3 - (p) concentrations. Further, they indicate that nocturnal production of NO3 - (p) in the RL, along with daytime photochemical production, can contribute substantially to the build-up and sustaining of severe pollution episodes. The exceptionally shallow nocturnal boundary layer heights characteristic of wintertime pollution events in the SJV intensifies the importance of nocturnal production aloft in the residual layer to daytime surface concentrations. The observations also demonstrate that dynamics within the RL can influence the early-morning vertical distribution of NO3 - (p), despite low wintertime wind speeds. This overnight reshaping of the vertical distribution above the city plays an important role in determining the net impact of nocturnal chemical production on local and regional surface-level NO3 - (p) concentrations. Entrainment of clean free tropospheric air into the boundary layer in the afternoon is identified as an important process that reduces surface-level NO3 - (p) and limits build-up during pollution episodes. The influence of dry deposition of HNO3 gas to the surface on daytime particulate nitrate concentrations is important but limited by an excess of ammonia in the region, which leads to only a small fraction of nitrate existing in the gas-phase even during the warmer daytime. However, in late afternoon, when diminishing solar heating leads to a rapid fall in the mixed boundary layer height, the impact of surface deposition is temporarily enhanced and can lead to a substantial decline in surface-level particulate nitrate concentrations; this enhanced deposition is quickly arrested by a decrease in surface temperature, which drops the gas-phase fraction to near zero. The overall importance of enhanced late afternoon gas-phase loss to the multiday build-up of pollution events is limited by the very shallow nocturnal boundary layer. The case study here demonstrates that mixing down of NO3 - (p) from the RL can contribute a majority of the surface-level NO3 - (p) in the morning (here, ~80%), and a strong influence can persist into the afternoon even when photochemical production is maximum. The particular day-to-day contribution of aloft nocturnal NO3 - (p) production to surface concentrations will depend on prevailing chemical and meteorological conditions. Although specific to the SJV, the observations and conceptual framework further developed here provide general insights into the evolution of pollution episodes in wintertime environments.
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Affiliation(s)
- Gouri Prabhakar
- Department of Civil and Environmental Engineering, University of California, Davis, CA, USA
| | - Caroline Parworth
- Department of Environmental Toxicology, University of California, Davis, CA, USA
| | - Xiaolu Zhang
- Department of Civil and Environmental Engineering, University of California, Davis, CA, USA
| | - Hwajin Kim
- Department of Environmental Toxicology, University of California, Davis, CA, USA
- Now at: Center for Environment, Health and Welfare Research, Korea Institute of Science and Technology, Seoul, South Korea
| | - Dominique Young
- Department of Environmental Toxicology, University of California, Davis, CA, USA
- Now at: Air Quality Research Center, University of California, Davis, California, USA
| | - Andreas J. Beyersdorf
- NASA Langley Research Center, Hampton, Virginia, USA
- Now at: Department of Chemistry, California State University, San Bernardino, CA, USA
| | | | - John B. Nowak
- NASA Langley Research Center, Hampton, Virginia, USA
| | | | - Ian C. Faloona
- Department of Land, Air and Water Resources, University of California, Davis, CA, USA
| | - Qi Zhang
- Department of Environmental Toxicology, University of California, Davis, CA, USA
| | - Christopher D. Cappa
- Department of Civil and Environmental Engineering, University of California, Davis, CA, USA
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13
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Xie M, Chen X, Hays MD, Lewandowski M, Offenberg J, Kleindienst TE, Holder AL. Light Absorption of Secondary Organic Aerosol: Composition and Contribution of Nitroaromatic Compounds. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:11607-11616. [PMID: 28930472 PMCID: PMC7372712 DOI: 10.1021/acs.est.7b03263] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Secondary organic aerosol (SOA) can affect the atmospheric radiation balance through absorbing light at shorter visible and UV wavelengths. However, the composition and optical properties of light-absorbing SOA is poorly understood. In this work, SOA filter samples were collected during individual chamber experiments conducted with three biogenic and eight aromatic volatile organic compound (VOC) precursors in the presence of NOX and H2O2. Compared with the SOA generated using the aromatic precursors, biogenic SOA generally exhibits negligible light absorption above 350 nm; the aromatic SOA generated in the presence of NOX shows stronger light absorption than that generated with H2O2. Fifteen nitroaromatic compound (NAC) chemical formulas were identified and quantified in SOA samples. Their contributions to the light absorption of sample extracts were also estimated. On average, the m-cresol/NOX SOA sample has the highest mass contribution from NACs (10.4 ± 6.74%, w/w), followed by naphthalene/NOX (6.41 ± 2.08%) and benzene/NOX (5.81 ± 3.82%) SOA. The average contributions of NACs to total light absorption were at least two times greater than their average mass contributions at 365 and 400 nm, revealing the potential use of chromophoric NACs as brown carbon (BrC) tracers in source apportionment and air quality modeling studies.
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Affiliation(s)
- Mingjie Xie
- School of Environmental Science and Engineering, Nanjing University of Information Science & Technology , Nanjing 210044, China
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14
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Light-absorbing organic carbon from prescribed and laboratory biomass burning and gasoline vehicle emissions. Sci Rep 2017; 7:7318. [PMID: 28779152 PMCID: PMC5544734 DOI: 10.1038/s41598-017-06981-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 06/20/2017] [Indexed: 11/08/2022] Open
Abstract
Light-absorbing organic carbon (OC), also termed brown carbon (BrC), from laboratory-based biomass burning (BB) has been studied intensively to understand the contribution of BB to radiative forcing. However, relatively few measurements have been conducted on field-based BB and even fewer measurements have examined BrC from anthropogenic combustion sources like motor vehicle emissions. In this work, the light absorption of methanol-extractable OC from prescribed and laboratory BB and gasoline vehicle emissions was examined using spectrophotometry. The light absorption of methanol extracts showed a strong wavelength dependence for both BB and gasoline vehicle emissions. The mass absorption coefficients at 365 nm (MAC365, m2 g-1C) - used as a measurement proxy for BrC - were significantly correlated (p < 0.05) to the elemental carbon (EC)/OC ratios when examined by each BB fuel type. No significant correlation was observed when pooling fuels, indicating that both burn conditions and fuel types may impact BB BrC characteristics. The average MAC365 of gasoline vehicle emission samples is 0.62 ± 0.76 m2 g-1C, which is similar in magnitude to the BB samples (1.27 ± 0.76 m2 g-1C). These results suggest that in addition to BB, gasoline vehicle emissions may also be an important BrC source in urban areas.
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15
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Shamjad PM, Tripathi SN, Thamban NM, Vreeland H. Refractive Index and Absorption Attribution of Highly Absorbing Brown Carbon Aerosols from an Urban Indian City-Kanpur. Sci Rep 2016; 6:37735. [PMID: 27883083 PMCID: PMC5121896 DOI: 10.1038/srep37735] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 10/31/2016] [Indexed: 11/09/2022] Open
Abstract
Atmospheric aerosols influence Earth's radiative balance, having both warming and cooling effects. Though many aerosols reflect radiation, carbonaceous aerosols such as black carbon and certain organic carbon species known as brown carbon have the potential to warm the atmosphere by absorbing light. Black carbon absorbs light over the entire solar spectrum whereas brown carbon absorbs near-UV wavelengths and, to a lesser extent, visible light. In developing countries, such as India, where combustion sources are prolific, the influence of brown carbon on absorption may be significant. In order to better characterize brown carbon, we present experimental and modeled absorption properties of submicron aerosols measured in an urban Indian city (Kanpur). Brown carbon here is found to be fivefold more absorbing at 365 nm wavelength compared to previous studies. Results suggest ~30% of total absorption in Kanpur is attributed to brown carbon, with primary organic aerosols contributing more than secondary organics. We report the spectral brown carbon refractive indices along with an experimentally constrained estimate of the influence of aerosol mixing state on absorption. We conclude that brown carbon in Kanpur is highly absorbing in nature and that the mixing state plays an important role in light absorption from volatile species.
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Affiliation(s)
- P. M. Shamjad
- Department of Civil Engineering, Indian Institute of Technology-Kanpur, Kanpur, India
| | - S. N. Tripathi
- Department of Civil Engineering, Indian Institute of Technology-Kanpur, Kanpur, India
- Centre for Environmental Science and Engineering, Indian Institute of Technology-Kanpur, Kanpur, India
| | - Navaneeth M. Thamban
- Department of Civil Engineering, Indian Institute of Technology-Kanpur, Kanpur, India
| | - Heidi Vreeland
- Department of Civil and Environmental Engineering, Duke University, North Carolina, USA
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