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Huang W, Ye X, Lv Z, Yao Y, Chen Y, Zhou Y, Chen J. Dual isotopic evidence of δ 15N and δ 18O for priority control of vehicle emissions in a megacity of East China: Insight from measurements in summer and winter. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 931:172918. [PMID: 38697522 DOI: 10.1016/j.scitotenv.2024.172918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2024] [Revised: 03/31/2024] [Accepted: 04/29/2024] [Indexed: 05/05/2024]
Abstract
The source apportionment and main formation pathway of nitrate aerosols in China are not yet fully understood. In this study, PM2.5 samples were collected in Shanghai in the summer and winter of 2019. Water-soluble inorganic ions and isotopic signatures of stable nitrogen (δ15N-NO3-) and stable oxygen (δ18O-NO3-) in PM2.5 were determined. The results showed that NO3- was less important in summer (NO3-/SO42- = 0.4 ± 0.8), while it became the dominant species in winter (52.1 %). The average values of δ15N-NO3- and δ18O-NO3- in summer were + 2.0 ± 6.1 ‰ and 63.3 ± 9.4 ‰ respectively, which were significantly lower than those in winter (+7.2 ± 3.4 ‰ and 88.3 ± 12.1 ‰), indicating discrepancies between NOx sources and nitrate formation pathways. Both δ15N-NO3- and δ18O-NO3- were elevated at night, demonstrating that N2O5 hydrolysis contributed to the nocturnal nitrate increase even in summer. The contribution of the OH oxidation pathway to nitrate aerosols averaged at 70.5 ± 17.0 % in summer and N2O5 hydrolysis dominated the nitrate production in winter (approximately 80 %). On average, vehicle exhaust, coal combustion, natural gas burning, and soil emission contributed 50.7 %, 21.5 %, 15.9 %, and 11.9 %, respectively, to nitrate aerosols in summer, and contributed 56.8 %, 23.9 %, 13.6 %, and 5.7 %, respectively, to nitrate production in winter. Notably, natural gas burning is a non-negligible source of nitrate aerosols in Shanghai. In contrast to an inverse correlation between δ15N-NO3- and PM2.5, the value of δ18O-NO3- was positively correlated with nitrate concentration and aerosol liquid water content (ALWC) in winter, suggesting that explosive growth of nitrate was driven by continuous accumulation of N-depleted NOx and rapid N2O5 hydrolysis under calm and humid conditions. To continuously improve air quality, priority control should be given to vehicle emissions as the dominant source of NOx and volatile organic compounds (VOCs) in Shanghai.
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Affiliation(s)
- Weijie Huang
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, Department of Environmental Science and Engineering, Fudan University, Shanghai 200438, China
| | - Xingnan Ye
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, Department of Environmental Science and Engineering, Fudan University, Shanghai 200438, China; Institute of Eco-Chongming (IEC), Chongming District, Shanghai 202162, China.
| | - Zhixiao Lv
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, Department of Environmental Science and Engineering, Fudan University, Shanghai 200438, China
| | - Yinghui Yao
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, Department of Environmental Science and Engineering, Fudan University, Shanghai 200438, China
| | - Yanan Chen
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, Department of Environmental Science and Engineering, Fudan University, Shanghai 200438, China
| | - Yuanqiao Zhou
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, Department of Environmental Science and Engineering, Fudan University, Shanghai 200438, China
| | - Jianmin Chen
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, Department of Environmental Science and Engineering, Fudan University, Shanghai 200438, China; Institute of Eco-Chongming (IEC), Chongming District, Shanghai 202162, China
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Deng M, Wang C, Yang C, Li X, Cheng H. Nitrogen and oxygen isotope characteristics, formation mechanism, and source apportionment of nitrate aerosols in Wuhan, Central China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 921:170715. [PMID: 38331296 DOI: 10.1016/j.scitotenv.2024.170715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Revised: 01/20/2024] [Accepted: 02/03/2024] [Indexed: 02/10/2024]
Abstract
Understanding the sources and formation mechanisms of nitrate in PM2.5 is important for effective and precise prevention and control of particulate matter pollution. In this study, we detected stable nitrogen and oxygen isotope signatures of NO- 3 (expressed as δ15N-NO- 3 and δ18O-NO3-) in PM2.5 samples in Wuhan, the largest city in central China. The sources and formation pathways of NO3- were quantitatively analyzed using the modified version of the Bayesian isotope mixing (MixSIR) model, and the regional transport characteristics of NO3- were analyzed using the hybrid single-particle Lagrangian integrated trajectory (HYSPLIT) model and concentration-weighted trajectory (CWT) method. The results showed that NO3- significantly contributed to the ambient PM2.5 pollution and its driving effect increased with the gradient of pollution level. The average δ15N-NO3- and δ18O-NO3- values were 4.7 ± 0.9 ‰ and 79.7 ± 2.9 ‰, respectively. δ15N-NO3- and δ18O-NO3- were more enriched in winter and increased dramatically in heavily polluted days. The reaction pathway of NO2 + OH dominated nitrate formation in summer, while the reaction pathway of N2O5+ H2O dominated in other seasons and contributed more in polluted days than clean days. The contributions of vehicle emission, coal combustion, biomass burning, biogenic soil emission, and ship emission sources to NO3- were 26.4 %, 23.4 %, 22.8 %, 15.3 %, and 12.1 %, respectively. In addition to local emissions, air mass transport from the northern China had a significant impact on particulate NO3- in Wuhan. Overall, we should pay special attention to vehicle and ship emissions and winter coal combustion emissions in future policymaking.
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Affiliation(s)
- Mengjie Deng
- School of Resource and Environmental Sciences, Wuhan University, Wuhan 430072, China
| | - Cimou Wang
- School of Resource and Environmental Sciences, Wuhan University, Wuhan 430072, China
| | - Chunmian Yang
- School of Resource and Environmental Sciences, Wuhan University, Wuhan 430072, China
| | - Xiaoxiao Li
- School of Resource and Environmental Sciences, Wuhan University, Wuhan 430072, China.
| | - Hairong Cheng
- School of Resource and Environmental Sciences, Wuhan University, Wuhan 430072, China.
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Song W, Liu XY. Source oxygen contributions of primary nitrate emitted from biomass burning. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 854:158736. [PMID: 36122720 DOI: 10.1016/j.scitotenv.2022.158736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 09/09/2022] [Accepted: 09/09/2022] [Indexed: 06/15/2023]
Abstract
Atmospheric nitrate (NO3-) produced by photochemical oxidation in the atmosphere has high oxygen isotope ratios (δ18O values). Recently, the primary NO3- emitted from combustion sources was found to have much lower δ18O values. However, it is unclear how and to what extents the low δ18O signatures were controlled by major O sources during the primary NO3- formation of combustion processes. Here, we first measured concentrations and δ18O values of NO3- from burning five biomass materials (bb-NO3- and δ18Obb-NO3-, respectively) in China. Distinctly higher concentration levels of the bb-NO3- emissions (42.1 ± 8.1 μmol m-3) than ambient NO3- suggest it is a potential source of atmospheric NO3- pollution. Much lower δ18Obb-NO3- signatures (27.6 ± 2.7 ‰) than ambient NO3- support it as a primary emission source with different O sources and formation mechanism from secondary NO3-. Isotope mass-balance modeling revealed that atmospheric O2 and the biomass O dominated the O of bb-NO3- (53 ± 7 % and 40 ± 4 %, respectively) over the aqueous vapor (7 ± 3 %). Besides, we found increasing δ18Obb-NO3- values with the biomass N contents and relatively lower δ18Obb-NO3- values for biomasses with higher carbon (C) and lower O contents, indicating that biomass C, N, and O contents may influence the source O contributions of the bb-NO3-. This work provides a novel isotope analysis on the O source contribution of the bb-NO3-, which is useful for understanding the formation mechanism of combustion-related NO3- sources and evaluating the primary NO3- emissions.
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Affiliation(s)
- Wei Song
- School of Earth System Science, Tianjin University, Tianjin 300072, China
| | - Xue-Yan Liu
- School of Earth System Science, Tianjin University, Tianjin 300072, China.
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Wang H, Lu K, Tan Z, Chen X, Liu Y, Zhang Y. Formation mechanism and control strategy for particulate nitrate in China. J Environ Sci (China) 2023; 123:476-486. [PMID: 36522007 DOI: 10.1016/j.jes.2022.09.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Revised: 09/14/2022] [Accepted: 09/14/2022] [Indexed: 06/17/2023]
Abstract
Over the past decade, fine particulate matter (PM) pollution in China has been abated significantly, benefiting from strict emission control measures, but particulate nitrate continues to rise. Here, we review the progress in particulate nitrate (pNO3-) pollution characterization, nitrate formation mechanisms, and the proposed control strategies in China. The spatial and temporal distributions of pNO3- are summarized. The current status of knowledge on the chemical mechanism is updated, and the significance of its formation pathways is assessed by various approaches such as field observation and modelling of nitrate production rate, as well as isotopic analysis. The factors impacting pNO3- formation and the corresponding pollution regulation strategies are discussed, in which the importance of atmospheric oxidation capacity and ammonia are addressed. Finally, the challenges and open questions in pNO3- pollution control in China are outlined.
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Affiliation(s)
- Haichao Wang
- School of Atmospheric Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Keding Lu
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
| | - Zhaofeng Tan
- Institute of Energy and Climate Research, IEK-8: Troposphere, Forschungszentrum Jülich GmbH, Jülich 52428, Germany
| | - Xiaorui Chen
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China
| | - Yuhan Liu
- China Institute of Atomic Energy, Beijing 100193, China
| | - Yuanhang Zhang
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
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Cheng C, Yu R, Chen Y, Yan Y, Hu G, Wang S. Quantifying the source and formation of nitrate in PM 2.5 using dual isotopes combined with Bayesian mixing model: A case study in an inland city of southeast China. CHEMOSPHERE 2022; 308:136097. [PMID: 35998735 DOI: 10.1016/j.chemosphere.2022.136097] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 08/10/2022] [Accepted: 08/15/2022] [Indexed: 06/15/2023]
Abstract
Atmospheric nitrate has been attracting increasing attention because it is one of the important components of PM2.5. Understanding the sources and formation mechanism of nitrate in PM2.5 is essential to take effective measures to prevent and control the emission of nitrogen oxides in the atmosphere and reduce the formation of haze. In this study, PM2.5 samples were collected from Ganzhou, an inland city in southeast China, during summer and winter. The concentrations of PM2.5 and NO3- were determined, and the isotopic compositions of NO3- (δ15N-NO3- and δ18O-NO3-) were analyzed in order to quantify the relative contributions of different emission sources and formation pathways of nitrate in PM2.5. The results showed that PM2.5 and NO3- concentrations were lower in summer (39.80 ± 11.10 μg·m-3 and 1.79 ± 0.70 μg·m-3) while higher in winter (69.85 ± 29.58 μg·m-3 and 10.83 ± 9.89 μg·m-3). The values of δ18O-NO3- and δ15N-NO3- ranged from 42.84‰ to 56.80‰ and from -11.17‰ to -2.08‰ in summer, while from 55.86‰ to 78.66‰ and from -10.63‰ to -1.88‰ in winter, respectively. The results of δ15N-NO3- combined with Bayesian isotope mixing model showed that the relative contributions of vehicle exhaust, soil microbial activity, biomass combustion and coal fired power plants were 59.3%, 28.5%, 8.7% and 3.4% in summer, while 65.1%, 20.1%, 10.6% and 4.1% in winter, respectively. The results of δ18O-NO3- combined with Bayesian isotope mixing model showed that the possible relative contributions of pathway 1 (P1) (NO2 + ·OH), pathway 2 (P2) (NO3 + HC) and pathway 3 (P3) (N2O5 + H2O) were 73.5%, 12.4% and 14.1% in summer, while 41.6%, 28.9% and 29.5% in winter, respectively. Moreover, P2 and P3 contributed more when NO3- concentrations were higher, suggesting that P2 and P3 were of significance to the formation of nitrate in PM2.5, especially during winter.
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Affiliation(s)
- Chen Cheng
- College of Chemical Engineering, Huaqiao University, Xiamen, 361021, China; Key Laboratory of Global Change and Marine-Atmospheric Chemistry, Third Institute of Oceanography, Ministry of Natural Resources, Xiamen, 361021, China
| | - Ruilian Yu
- College of Chemical Engineering, Huaqiao University, Xiamen, 361021, China.
| | - Yanting Chen
- Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China
| | - Yu Yan
- College of Chemical Engineering, Huaqiao University, Xiamen, 361021, China; Key Laboratory of Global Change and Marine-Atmospheric Chemistry, Third Institute of Oceanography, Ministry of Natural Resources, Xiamen, 361021, China
| | - Gongren Hu
- College of Chemical Engineering, Huaqiao University, Xiamen, 361021, China; Institute of Environmental and Ecological Engineering, Huaqiao University, Xiamen, 361021, China.
| | - Shanshan Wang
- Key Laboratory of Global Change and Marine-Atmospheric Chemistry, Third Institute of Oceanography, Ministry of Natural Resources, Xiamen, 361021, China
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Young LH, Hsiao TC, Griffith SM, Huang YH, Hsieh HG, Lin TH, Tsay SC, Lin YJ, Lai KL, Lin NH, Lin WY. Secondary inorganic aerosol chemistry and its impact on atmospheric visibility over an ammonia-rich urban area in Central Taiwan. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 312:119951. [PMID: 36002097 DOI: 10.1016/j.envpol.2022.119951] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Revised: 08/01/2022] [Accepted: 08/08/2022] [Indexed: 06/15/2023]
Abstract
This study investigated the hourly inorganic aerosol chemistry and its impact on atmospheric visibility over an urban area in Central Taiwan, by relying on measurements of aerosol light extinction, inorganic gases, and PM2.5 water-soluble ions (WSIs), and simulations from a thermodynamic equilibrium model. On average, the sulfate (SO42-), nitrate (NO3-), and ammonium (NH4+) components (SNA) contributed ∼90% of WSI concentrations, which in turn made up about 50% of the PM2.5 mass. During the entire observation period, PM2.5 and SNA concentrations, aerosol pH, aerosol liquid water content (ALWC), and sulfur and nitrogen conversion ratios all increased with decreasing visibility. In particular, the NO3- contribution to PM2.5 increased, whereas the SO42- contribution decreased, with decreasing visibility. The diurnal variations of the above parameters indicate that the interaction and likely mutual promotion between NO3- and ALWC enhanced the hygroscopicity and aqueous-phase reactions conducive for NO3- formation, thus led to severely impaired visibility. The high relative humidity (RH) at the study area (average 70.7%) was a necessary but not sole factor leading to enhanced NO3- formation, which was more directly associated with elevated ALWC and aerosol pH. Simulations from the thermodynamic model depict that the inorganic aerosol system in the study area was characterized by fully neutralized SO42- (i.e. a saturated factor in visibility reduction) and excess NH4+ amidst a NH3-rich environment. As a result, PM2.5 composition was most sensitive to gas-phase HNO3, and hence NOx, and relatively insensitive to NH3. Consequently, a reduction of NOx would result in instantaneous cuts of NO3-, PM2.5, and ALWC, and hence improved visibility. On the other hand, a substantial amount of NH3 reduction (>70%) would be required to lower the aerosol pH, driving more than 50% of the particulate phase NO3- to the gas phase, thereby making NH3 a limiting factor in shifting PM2.5 composition.
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Affiliation(s)
- Li-Hao Young
- Department of Occupational Safety and Health, China Medical University, 100, Sec. 1, Jingmao Rd., Beitun Dist., Taichung, 406040, Taiwan.
| | - Ta-Chih Hsiao
- Graduate Institute of Environmental Engineering, National Taiwan University, 1, Sec. 4, Roosevelt Rd., Taipei, 10617, Taiwan
| | - Stephen M Griffith
- Department of Atmospheric Sciences, National Central University, 300, Zhongda Rd., Zhongli Dist., Taoyuan, 320317, Taiwan
| | - Ya-Hsin Huang
- Department of Occupational Safety and Health, China Medical University, 100, Sec. 1, Jingmao Rd., Beitun Dist., Taichung, 406040, Taiwan
| | - Hao-Gang Hsieh
- Department of Occupational Safety and Health, China Medical University, 100, Sec. 1, Jingmao Rd., Beitun Dist., Taichung, 406040, Taiwan
| | - Tang-Huang Lin
- Center for Space and Remote Sensing Research, National Central University, 300, Zhongda Rd., Zhongli Dist., Taoyuan, 320317, Taiwan
| | - Si-Chee Tsay
- NASA Goddard Space Flight Center, Greenbelt, MD, 20771, USA
| | - Yu-Jung Lin
- Department of Occupational Safety and Health, China Medical University, 100, Sec. 1, Jingmao Rd., Beitun Dist., Taichung, 406040, Taiwan
| | - Kuan-Lin Lai
- Department of Occupational Safety and Health, China Medical University, 100, Sec. 1, Jingmao Rd., Beitun Dist., Taichung, 406040, Taiwan
| | - Neng-Huei Lin
- Department of Atmospheric Sciences, National Central University, 300, Zhongda Rd., Zhongli Dist., Taoyuan, 320317, Taiwan
| | - Wen-Yinn Lin
- Institute of Environmental Engineering and Management, National Taipei University of Technology, 1, Sec. 3, Chung-Hsiao E. Rd., Taipei, 106344, Taiwan
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Assessment of NO2 Purification by Urban Forests Based on the i-Tree Eco Model: Case Study in Beijing, China. FORESTS 2022. [DOI: 10.3390/f13030369] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Air quality issues caused by nitrogen dioxide (NO2) have become increasingly serious in Chinese cities in recent years. As important urban green infrastructure, urban forests can mitigate gaseous nitrogen pollution by absorbing NO2 through leaf gas exchange. This study investigated spatiotemporal variations in the NO2 removal capacity of urban forests in Beijing city from 2014–2019, based on the i-Tree Eco deposition model. The results show that the annual removal capacity of administrative districts within Beijing city ranged from 14,910 to 17,747 tons, and the largest capacity (2684 tons) was found in the Fangshan district. The annual removal rate of NO2 by urban forests in administrative districts within Beijing was estimated at between 0.50–1.60 g/m2, reaching the highest (1.47 g/m2) in the Mengtougou district. The annual average absorption of NO2 by urban forests can account for 0.14–2.60% of annual total atmospheric NO2 and potentially reduce the NO2 concentration by 0.10–0.34 µg/m3 on average. The results of a principal component analysis suggest that the distribution of urban forests in Beijing is not optimized to maximize their NO2 removal capacity, being higher in suburban areas and lower in urban areas. This study provides insights into botanical NO2 removal capacity in Beijing city to mitigate atmospheric N pollution, addressing the key role of urban forests in improving human wellbeing.
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Shi Y, Tian P, Jin Z, Hu Y, Zhang Y, Li F. Stable nitrogen isotope composition of NO x of biomass burning in China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 803:149857. [PMID: 34496345 DOI: 10.1016/j.scitotenv.2021.149857] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/25/2021] [Accepted: 08/19/2021] [Indexed: 06/13/2023]
Abstract
Owing to the local characteristics of stable nitrogen isotopes in nitrogen oxides (δ15N-NOx) emitted from biomass burning, the lack of data on δ15N-NOx values associated with biomass burning in China limits the use of this parameter in identifying and quantifying the sources of atmospheric nitrate (NO3-) and NOx. The results showed that the δ15N-NOx values of open burning and rural cooking stoves in China ranged from -3.7‰ to 3.1‰ and -11.9‰ to 1.5‰, respectively. The δ15N values of nine biomass fuel sources (δ15N-biomass) ranged from 0.1‰ to 4.1‰. Significant linear relationships between the δ15N-biomass values and δ15N-NOx values of open burning (δ15N-NOx = 1.1δ15N-biomass - 2.7; r2 = 0.63; p < 0.05) and rural cooking stoves (δ15N-NOx = 1.7δ15N-biomass - 9.8; r2 = 0.72; p < 0.01) suggested that the variations in δ15N-NOx values from biomass burning were mainly controlled by the biomass fuel source. The isotopic fractionation of nitrogen during the biomass burning process might have led to the higher δ15N-NOx values from open burning in comparison to rural cooking stoves. By combining the δ15N-NOx values of biomass burning with biomass burning emission inventory data, a model for calculating the δ15N-NOx values of biomass burning in different regions of China was established, and the estimated δ15N-NOx value of biomass burning at the national scale was -0.8 ± 1.2‰. But the limited δ15N-biomass values increase the uncertainty of model in national scale.
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Affiliation(s)
- Yasheng Shi
- College of Environment, Zhejiang University of Technology, Hangzhou 310032, China
| | - Ping Tian
- Zhejiang Zone-King Environmental Sci & Tech Co., Ltd, Hanghzou 310004, China
| | - Zanfang Jin
- College of Environment, Zhejiang University of Technology, Hangzhou 310032, China.
| | - Yuming Hu
- Zhejiang Zone-King Environmental Sci & Tech Co., Ltd, Hanghzou 310004, China
| | - Yongqi Zhang
- College of Environment, Zhejiang University of Technology, Hangzhou 310032, China
| | - Feili Li
- College of Environment, Zhejiang University of Technology, Hangzhou 310032, China
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Gu Y, Liu B, Dai Q, Zhang Y, Zhou M, Feng Y, Hopke PK. Multiply improved positive matrix factorization for source apportionment of volatile organic compounds during the COVID-19 shutdown in Tianjin, China. ENVIRONMENT INTERNATIONAL 2022; 158:106979. [PMID: 34991244 DOI: 10.1016/j.envint.2021.106979] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 10/13/2021] [Accepted: 11/10/2021] [Indexed: 06/14/2023]
Abstract
Ambient concentrations of volatile organic compounds (VOCs) vary with emission rates, meteorology, and chemistry. Conventional positive matrix factorization (PMF) loses information because of dilution variations and chemical losses. Multiply improved PMF incorporates the ventilation coefficient, and total solar radiation or oxidants to reduce the effects of dispersion and chemical loss. These methods were applied to hourly speciated VOC data from November 2019 to March 2020 including during the COVID-19 shutdown. Various comparisons were made to assess the influences of these fluctuation drivers by time of day. Dispersion normalized PMF (DN-PMF) reduced the dispersion variations. Dispersion-radiation normalized PMF (DRN-PMF) reduced the impact of chemical loss, especially at night, which was better than Dispersion-Ox normalized PMF (DON-PMF). The conditional bivariate probability function (CBPF) plots of DRN-PMF results were consist with actual source locations. The DN-PMF, DRN-PMF, and DON-PMF results were consistent between 10:00 and 15:00, suggesting dispersion was significantly more influential than photochemical reactions during these times. The DRN-PMF results indicated that the highest VOC contributors during the COVID-19 shutdown were liquefied petroleum gas (LPG) (28.8%), natural gas (25.2%), and pulverized coal boilers emissions (19.6%). Except for petrochemical-related enterprises and LPG, the contribution concentrations of all other sources decreased substantially during the COVID-19 shutdown, by 94.7%, 90.6%, and 86.8% for vehicle emissions, gasoline evaporation, and the mixed source of diesel evaporation and solvent use, respectively. Controlling the use of motor vehicles and related volatilization of diesel fuel and gasoline can be effective in controlling VOCs in the future.
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Affiliation(s)
- Yao Gu
- State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control & Tianjin Key Laboratory of Urban Transport Emission Research, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China; CMA-NKU Cooperative Laboratory for Atmospheric Environment-Health Research, Tianjin 300350, China
| | - Baoshuang Liu
- State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control & Tianjin Key Laboratory of Urban Transport Emission Research, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China; CMA-NKU Cooperative Laboratory for Atmospheric Environment-Health Research, Tianjin 300350, China.
| | - Qili Dai
- State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control & Tianjin Key Laboratory of Urban Transport Emission Research, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China; CMA-NKU Cooperative Laboratory for Atmospheric Environment-Health Research, Tianjin 300350, China
| | - Yufen Zhang
- State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control & Tianjin Key Laboratory of Urban Transport Emission Research, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China; CMA-NKU Cooperative Laboratory for Atmospheric Environment-Health Research, Tianjin 300350, China
| | - Ming Zhou
- State Key Joint Laboratory of Environment Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
| | - Yinchang Feng
- State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control & Tianjin Key Laboratory of Urban Transport Emission Research, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China; CMA-NKU Cooperative Laboratory for Atmospheric Environment-Health Research, Tianjin 300350, China
| | - Philip K Hopke
- Department of Public Health Sciences, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA; Institute for a Sustainable Environment, Clarkson University, Potsdam, NY 13699, USA
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