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Fan R, Ma Y, Cao W, Jin S, Liu B, Wang W, Li H, Gong W. New insights into black carbon light absorption enhancement: A comprehensive analysis of two differential behaviors. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 355:124175. [PMID: 38761879 DOI: 10.1016/j.envpol.2024.124175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 04/28/2024] [Accepted: 05/15/2024] [Indexed: 05/20/2024]
Abstract
High uncertainty in optical properties of black carbon (BC) involving heterogeneous chemistry has recently attracted increasing attention in the field of atmospheric climatology. To fill the gap in BC optical knowledge so as to estimate more accurate climate effects and serve the response to global warming, it is beneficial to conduct site-level studies on BC light absorption enhancement (Eabs) characteristics. Real-time surface gas and particulate pollutant observations during the summer and winter over Wuhan were utilized for the analysis of Eabs simulated by minimum R squared (MRS), considering two distinct atmospheric conditions (2015 and 2017). In general, differences in aerosol emissions led to Eabs differential behaviors. The summer average of Eabs (1.92 ± 0.55) in 2015 was higher than the winter average (1.27 ± 0.42), while the average (1.11 ± 0.20) in 2017 summer was lower than that (1.67 ± 0.69) in winter. Eabs and RBC (representing the mass ratio of non-refractory constituents to elemental carbon) constraints suggest that Eabs increased with the increase in RBC under the ambient condition enriched by secondary inorganic aerosol (SIA), with a maximum growth rate of 70.6% in 2015 summer. However, Eabs demonstrated a negative trend against RBC in 2017 winter due to the more complicated mixing state. The result arose from the opposite impact of hygroscopic SIA and absorbing OC/irregular distributed coatings on amplifying the light absorbency of BC. Furthermore, sensitivity analysis revealed a robust positive correlation (R > 0.9) between aerosol chemical compositions (including sulfate, nitrate, ammonium and secondary organic carbon), which could be significantly perturbed by only a small fraction of absorbing materials or restructuring BC through gaps filling. The above findings not only deepen the understanding of BC, but also provide useful information for the scientific decision-making in government to mitigate particulate pollution and obtain more precise BC radiative forcing.
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Affiliation(s)
- Ruonan Fan
- State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan, 430079, China
| | - Yingying Ma
- State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan, 430079, China; Hubei Luojia Laboratory, Wuhan, 430079, China.
| | - Wenxiang Cao
- Eco-Environmental Monitoring Centre of Hubei Province, Wuhan, 430072, China
| | - Shikuan Jin
- State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan, 430079, China
| | - Boming Liu
- State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan, 430079, China
| | - Weiyan Wang
- State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan, 430079, China
| | - Hui Li
- School of Electronic Information, Wuhan University, Wuhan, 430079, China
| | - Wei Gong
- School of Electronic Information, Wuhan University, Wuhan, 430079, China
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Feng T, Liu L, Zhao S. Impacts of haze and nitrogen oxide alleviation on summertime ozone formation: A modeling study over the Yangtze River Delta, China. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 335:122347. [PMID: 37562528 DOI: 10.1016/j.envpol.2023.122347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Revised: 08/02/2023] [Accepted: 08/07/2023] [Indexed: 08/12/2023]
Abstract
The strict emission control measures have profoundly changed the air pollution in the Yangtze River Delta (YRD) region, China. However, the impacts of decreasing fine particulates (PM2.5) and nitrogen oxide (NOx) on summer ozone (O3) formation still remain disputable. We perform simulations in the 2018 summer over the YRD using the WRF-Chem model that considers the aerosol radiative forcing (ARF) and HO2 heterogeneous loss on aerosol surface. The model reasonably reproduces the measured spatiotemporal surface O3 and PM2.5 concentrations and aerosol compositions. Model sensitivity experiments show that the NOx mitigation during recent years changes daytime O3 formation in summer from the transition regime to the NOx-sensitive regime in the YRD. The decreasing NOx emission generally weakens O3 formation and lowers ambient O3 levels in summer during recent years, except for some urban centers of megacities. While, the haze alleviation characterized by a decline in ambient PM2.5 concentration in the past years largely counteracts the daytime O3 decrease caused by NOx mitigation, largely contributing to the persistently high levels of summertime O3. The counteracting effect is dominantly attributed to the attenuated ARF and minorly contributed by the suppressed HO2 uptake and heterogeneous loss on aerosol surface. These results highlight that the repeated O3 pollution in the YRD is closely associated with NOx and haze alleviation and more efforts must be taken to achieve lower O3 levels.
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Affiliation(s)
- Tian Feng
- Department of Geography & Spatial Information Techniques, Ningbo University, Ningbo, Zhejiang, 315211, China; Institute of East China Sea, Ningbo University, Ningbo, Zhejiang, 315211, China.
| | - Lang Liu
- College of Meteorology and Oceanography, National University of Defense Technology, Changsha, Hunan, 410073, China
| | - Shuyu Zhao
- Ningbo Meteorological Bureau, Ningbo, Zhejiang, 315012, China
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3
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Cui Y, Li Z, Xiao Q, Ge J, Jiang W, Wang X, Wang Z, Yuan Y, Zhuang Y, Hao W, Jiang J, Meng Q, Wei X. 1,4-Naphthoquinone-coated black carbon nanoparticles up-regulation POR/FTL/IL-33 axis in THP1 cells. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 249:114381. [PMID: 36508801 DOI: 10.1016/j.ecoenv.2022.114381] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 11/28/2022] [Accepted: 11/30/2022] [Indexed: 06/17/2023]
Abstract
Black carbon (BC) is an important component of atmospheric PM 2.5 and the second largest contributor to global warming. 1,4-naphthoquinone-coated BC (1,4 NQ-BC) is a secondary particle with great research value, so we chose 1,4 NQ-BC as the research object. In our study, mitochondria and lysosomes were selected as targets to confirm whether they were impaired by 1,4 NQ-BC, label free proteomics technology, fluorescent probes, qRT-PCR and western blots were used to investigate the mechanism of 1,4 NQ-BC toxicity. We found 494 differentially expressed proteins (DEPs) in mitochondria and 86 DEPs in lysosomes using a proteomics analysis of THP1 cells after 1,4 NQ-BC exposure for 24 h. Through proteomics analysis and related experiments, we found that 1,4 NQ-BC can damage THP-1-M cells by obstructing autophagy, increasing lysosomal membrane permeability, disturbing the balance of ROS, and reducing the mitochondrial membrane potential. It is worth noting that 1,4 NQ-BC prevented the removal of FTL by inhibiting autophagy, and increased IL-33 level by POR/FTL/IL-33 axis. We first applied proteomics to study the damage mechanism of 1,4 NQ-BC on THP1 cells. Our research will enrich knowledge of the mechanism by which 1,4 NQ-BC damages human macrophages and identify important therapeutic targets and adverse outcome pathways for 1,4 NQ-BC-induced damage.
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Affiliation(s)
- Yuan Cui
- Department of Toxicology, School of Public Health, Peking University, Beijing 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing 100191, PR China
| | - Zekang Li
- Department of Toxicology, School of Public Health, Peking University, Beijing 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing 100191, PR China
| | - Qianqian Xiao
- Department of Toxicology, School of Public Health, Peking University, Beijing 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing 100191, PR China
| | - Jianhong Ge
- Department of Toxicology, School of Public Health, Peking University, Beijing 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing 100191, PR China
| | - Wanyu Jiang
- Department of Toxicology, School of Public Health, Peking University, Beijing 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing 100191, PR China
| | - Xiaoyun Wang
- Department of Toxicology, School of Public Health, Peking University, Beijing 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing 100191, PR China
| | - Zhenyu Wang
- Department of Toxicology, School of Public Health, Peking University, Beijing 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing 100191, PR China
| | - Yuese Yuan
- Department of Toxicology, School of Public Health, Peking University, Beijing 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing 100191, PR China
| | - Yimeng Zhuang
- Department of Toxicology, School of Public Health, Peking University, Beijing 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing 100191, PR China
| | - Weidong Hao
- Department of Toxicology, School of Public Health, Peking University, Beijing 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing 100191, PR China
| | - Jianjun Jiang
- Department of Toxicology, School of Public Health, Peking University, Beijing 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing 100191, PR China
| | - Qinghe Meng
- Department of Toxicology, School of Public Health, Peking University, Beijing 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing 100191, PR China
| | - Xuetao Wei
- Department of Toxicology, School of Public Health, Peking University, Beijing 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing 100191, PR China.
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Gao J, Li Y, Xie Z, Wang L, Hu B, Bao F. Which aerosol type dominate the impact of aerosols on ozone via changing photolysis rates? THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 854:158580. [PMID: 36075440 DOI: 10.1016/j.scitotenv.2022.158580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 09/01/2022] [Accepted: 09/03/2022] [Indexed: 06/15/2023]
Abstract
The impact of aerosols on ozone via influencing photolysis rates is a combined effect of absorbing aerosols (AA) and scattering aerosols (SA). However, AA and SA show different optical properties and influence photolysis rates differently, which then cause different impacts on ozone. Till now, the dominate factor is disconfirmed, which is largely due to the impact of SA on ozone not reaching to a consistent conclusion. In this study, the WRF-Chem model was implemented to simulate the air pollutants over the North China Plain (NCP). The impacts of AA and SA on ozone via influencing photolysis rates were quantitatively isolated and analyzed. Our results also demonstrated the decreasing effect of AA on ozone within planet boundary layer (PBL) which is consistent with the conclusions of previous studies. But for SA, it decreased the ozone chemical contribution (CHEM) near surface but increased which in the upper layers of PBL, that enlarge the ozone vertical gradients. In this case, more vertical exchanges of ozone would occur with the effect of vertical mixing motion of atmosphere, then the opposite CHEM variations were counteracted with each other and finally led to very slight changes in ozone within PBL. Thus, it can be summarized that AA dominate this impact of aerosols on ozone. Reducing AA could cause a general increase in ozone (ΔO3) over the NCP. Based on the aerosol levels of this case, ΔO3 would be seen over 86 % of the areas in the NCP when reducing AA by 3/4 and ΔO3 was more significant in the megacities. Our study highlights the different relationships between ozone and aerosol types, which suggests that more attentions should be paid on aerosol types, especially AA, when making the synergetic control strategy of aerosols and ozone in China.
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Affiliation(s)
- Jinhui Gao
- Plateau Atmosphere and Environment Key Laboratory of Sichuan Province, School of Atmospheric Sciences, Chengdu University of Information Technology, Chengdu, China; Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, China; Center for the Oceanic and Atmospheric Science at SUSTech (COAST), Southern University of Science and Technology, Shenzhen, China
| | - Ying Li
- Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, China; Center for the Oceanic and Atmospheric Science at SUSTech (COAST), Southern University of Science and Technology, Shenzhen, China.
| | - Zhouqing Xie
- Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei, China
| | - Lili Wang
- State Key Laboratory of Atmosphere Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
| | - Bo Hu
- State Key Laboratory of Atmosphere Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
| | - Fangwen Bao
- Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, China; Center for the Oceanic and Atmospheric Science at SUSTech (COAST), Southern University of Science and Technology, Shenzhen, China
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5
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Zhang T, Shen Z, Huang S, Lei Y, Zeng Y, Sun J, Zhang Q, Ho SSH, Xu H, Cao J. Optical properties, molecular characterizations, and oxidative potentials of different polarity levels of water-soluble organic matters in winter PM 2.5 in six China's megacities. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 853:158600. [PMID: 36089047 DOI: 10.1016/j.scitotenv.2022.158600] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 08/29/2022] [Accepted: 09/04/2022] [Indexed: 06/15/2023]
Abstract
Humic-like substances (HULIS) accounted for a great fraction of water-soluble organic matter (WSOM) in PM2.5, which efficiently absorb ultraviolet (UV) radiation and pose climate and health impacts. In this study, the molecular structure, optical properties, and oxidative potential (OP) of acid- and neutral-HULIS (denoted as HULIS-a, and HULIS-n, respectively), and high-polarity WSOM (HP-WSOM) were investigated in winter PM2.5 collected at six China's megacities. For both carbon levels and optical absorption coefficients (babs_365), HULIS-a/HULIS-n/HP-WSOM showed significant spatial differences. For each city, the carbon levels and babs_365 follow a similar order of HULIS-n > HULIS-a > HP-WSOM. Besides, the babs_365 of HULIS-n and HULIS-a showed the same order of Harbin > Beijing ≈ Wuhan > Xi'an > Guangzhou > Chengdu, while HP-WSOM exhibited an order of Wuhan > Chengdu > Xi'an > Harbin > Beijing > Guangzhou. Both HULIS-a and HULIS-n were abundant in aromatic and aliphatic compounds, whereas HP-WSOM was dominated by a carboxylic acid group. The OP (in unit of nmol H2O2 μg-1C) followed the order of HP-WSOM > HULIS-a > HULIS-n in all the cities. The OPs of HULIS-a, HULIS-n, and HP-WSOM in Harbin and Beijing were much higher than those of other cities, attributing to the high contribution from biomass burning. Highly positive correlations between reactive oxygen species (ROS) of HULIS-a and MAE365 were obtained in Chengdu, Wuhan, and Harbin, but ROS of HULIS-n had stronger correlation with MAE365 in Harbin, Chengdu, and Xi'an.
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Affiliation(s)
- Tian Zhang
- Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China; Key Lab of Aerosol Chemistry & Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China
| | - Zhenxing Shen
- Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China; Key Lab of Aerosol Chemistry & Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China.
| | - Shasha Huang
- Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Yali Lei
- Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Yaling Zeng
- Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Jian Sun
- Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Qian Zhang
- Key Laboratory of Northwest Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Steven Sai Hang Ho
- Division of Atmospheric Sciences, Desert Research Institute, Reno, NV 89512, United States
| | - Hongmei Xu
- Department of Environmental Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Junji Cao
- Key Lab of Aerosol Chemistry & Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China
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Zhang F, Peng J, Chen L, Collins D, Li Y, Jiang S, Liu J, Zhang R. The effect of black carbon aging from NO 2 oxidation of SO 2 on its morphology, optical and hygroscopic properties. ENVIRONMENTAL RESEARCH 2022; 212:113238. [PMID: 35395235 DOI: 10.1016/j.envres.2022.113238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Revised: 02/25/2022] [Accepted: 03/31/2022] [Indexed: 06/14/2023]
Abstract
Atmospheric aging of black carbon (BC) leads to changes in its physiochemical properties, exerting complex effects on environment and climate. In this study, we have conducted laboratory chamber experiments to investigate the effects of BC aging on its morphology, hygroscopicity and optical properties by exposing monodisperse fresh BC particles to ambient ubiquitous species of nitrogen dioxide (NO2), sulfur dioxide (SO2) and ammonia (NH3) in absence of UV light. We show a rapid aging from highly fractal to compacted aggregates for the monodisperse BC particles with an initial diameter of 150 nm, with decline in the dynamic shape factor (χ) from about 1.8 to nearly 1. The effective density of the monodisperse BC particles increases from ∼0.54 to 1.50 g cm-3 accordingly. The aging process leads to that the light scattering, absorption, and single scattering albedo of the monodisperse BC particles are strongly enhanced by factors of 7.0, 1.8 and 3.0 respectively. By comparing with the BC aging from other mechanisms, we reveal a critical role of the composition of the coating materials on BC in determining its light absorption enhancement. Moreover, due to strong water uptake capacity of the aged BC particles, the light absorption enhancement (Eabs) could be 40-60% higher at humid atmosphere compared with dry conditions. This BC aging process from NO2 oxidation of SO2 may occur commonly in polluted regions and thus considerably alter its effects on regional air quality and climate.
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Affiliation(s)
- Fang Zhang
- School of Civil and Environmental Engineering, Harbin Institute of Technology (Shenzhen), 518055, Shenzhen, China
| | - Jianfei Peng
- Departments of Atmospheric Sciences and Chemistry, Texas A&M University, College Station, TX, USA; Tianjin Key Laboratory of Urban Transport Emission Research, College of Environmental Science and Engineering, Nankai University, Tianjin, 300071, China
| | - Lu Chen
- College of Global Change and Earth System Science, Beijing Normal University, Beijing, 100875, China
| | - Don Collins
- Chemical and Environmental Engineering, University of California, Riverside, CA, 92521, USA
| | - Yixin Li
- Departments of Atmospheric Sciences and Chemistry, Texas A&M University, College Station, TX, USA
| | - Sihui Jiang
- College of Global Change and Earth System Science, Beijing Normal University, Beijing, 100875, China
| | - Jieyao Liu
- College of Global Change and Earth System Science, Beijing Normal University, Beijing, 100875, China
| | - Renyi Zhang
- Departments of Atmospheric Sciences and Chemistry, Texas A&M University, College Station, TX, USA.
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Wang Y, Li X, Wang Q, Zhou B, Liu S, Tian J, Hao Q, Li G, Han Y, Hang Ho SS, Cao J. Response of aerosol composition to the clean air actions in Baoji city of Fen-Wei River Basin. ENVIRONMENTAL RESEARCH 2022; 210:112936. [PMID: 35181303 DOI: 10.1016/j.envres.2022.112936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 12/27/2021] [Accepted: 02/08/2022] [Indexed: 06/14/2023]
Abstract
The implementation of air pollution control measures could alter the compositions of submicron aerosols. Identifying the changes can evaluate the atmospheric responses of the implemented control measures and provide more scientific basis for the formulation of new measures. The Fen-Wei River Basin is the most air polluted region in China, and thereby is a key area for the reduction of emissions. Only limited studies determine the changes in the chemical compositions of submicron aerosols. In this study, Baoji was selected as a representative city in the Fen-Wei River Basin. The compositions of submicron aerosols were determined between 2014 and 2019. Organic fractions were determined through an online instrument (Quadrupole Aerosol Chemical Speciation Monitor, Q-ACSM) and source recognition was performed by the Multilinear Engine (ME-2). The Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) was also employed to evaluate the contributions of emissions reduction and meteorological conditions to the changes of submicron aerosol compositions. The results indicate that the mass concentrations of submicron aerosols have been substantially decreased after implementation of air pollution control measures. This was mainly attributed to the emission reductions of sulfur dioxide (SO2) and primary organic aerosol (POA). In addition, the main components that drove the pollution episodes swapped from POA, sulfate, nitrate and less-oxidized organic (LO-OOA) in 2014 to nitrate and more-oxidized OOA (MO-OOA) in 2019. Due to the changes of chemical compositions of both precursors and secondary pollutants, the pollution control measures should be modernized to focus on the emissions of ammonia (NH3), nitrogen oxides (NOx) and volatile organic compounds (VOCs) in this region.
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Affiliation(s)
- Yichen Wang
- School of Public Policy and Administration, Northwestern Polytechnical University, Xi'an, 710129, China
| | - Xia Li
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China
| | - Qiyuan Wang
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an, 710061, China; Guanzhong Plain Ecological Environment Change and Comprehensive Treatment National Observation and Research Station, China.
| | - Bianhong Zhou
- Shaanxi Key Laboratory of Disaster Monitoring and Mechanism Simulation, College of Geography & Environment, Baoji University of Arts & Sciences, Baoji, 721013, China
| | - Suixin Liu
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China
| | - Jie Tian
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China
| | - Qiang Hao
- Future Lab, Tsinghua University, Beijing, China
| | - Guohui Li
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China
| | - Yongming Han
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an, 710061, China; Guanzhong Plain Ecological Environment Change and Comprehensive Treatment National Observation and Research Station, China
| | - Steven Sai Hang Ho
- Division of Atmospheric Sciences, Desert Research Institute, Reno, NV89512, United States
| | - Junji Cao
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an, 710061, China.
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Li X, Bei N, Wu J, Wang R, Liu S, Liu L, Jiang Q, Tie X, Molina LT, Li G. Heterogeneous HONO formation deteriorates the wintertime particulate pollution in the Guanzhong Basin, China. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 303:119157. [PMID: 35304175 DOI: 10.1016/j.envpol.2022.119157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 03/03/2022] [Accepted: 03/14/2022] [Indexed: 06/14/2023]
Abstract
Despite implementation of strict emission mitigation measures since 2013, heavy haze with high levels of secondary aerosols still frequently engulfs the Guanzhong Basin (GZB), China, during wintertime, remarkably impairing visibility and potentially causing severe health issues. Although the observed low ozone (O3) concentrations do not facilitate the photochemical formation of secondary aerosols, the measured high nitrous acid (HONO) level provides an alternate pathway in the GZB. The impact of heterogeneous HONO sources on the wintertime particulate pollution and atmospheric oxidizing capability (AOC) is evaluated in the GZB. Simulations by the Weather Research and Forecast model coupled with Chemistry (WRF-Chem) reveal that the observed high levels of nitrate and secondary organic aerosols (SOA) are reproduced when both homogeneous and heterogeneous HONO sources are considered. The heterogeneous sources (HET-sources) contribute about 98% of the near-surface HONO concentration in the GZB, increasing the hydroxyl radical (OH) and O3 concentration by 39.4% and 22.0%, respectively. The average contribution of the HET-sources to SOA, nitrate, ammonium, and sulfate in the GZB is 35.6%, 20.6%, 12.1%, and 6.0% during the particulate pollution episode, respectively, enhancing the mass concentration of fine particulate matters (PM2.5) by around 12.2%. Our results suggest that decreasing HONO level or the AOC becomes an effective pathway to alleviate the wintertime particulate pollution in the GZB.
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Affiliation(s)
- Xia Li
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Naifang Bei
- School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Jiarui Wu
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China
| | - Ruonan Wang
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China
| | - Suixin Liu
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China
| | - Lang Liu
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China
| | - Qian Jiang
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China
| | - Xuexi Tie
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China
| | - Luisa T Molina
- Molina Center for Energy and the Environment, La Jolla, CA, 92037, USA
| | - Guohui Li
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an, 710061, China.
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9
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Gao J, Li Y, Xie Z, Hu B, Wang L, Bao F, Fan S. The impact of the aerosol reduction on the worsening ozone pollution over the Beijing-Tianjin-Hebei region via influencing photolysis rates. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 821:153197. [PMID: 35063532 DOI: 10.1016/j.scitotenv.2022.153197] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/10/2022] [Accepted: 01/12/2022] [Indexed: 06/14/2023]
Abstract
Due to the implementation of the toughest-ever emission control actions across China from 2013 to present, the aerosols are decreasing annually but ozone is simultaneously increasing, especially over the Beijing-Tianjin-Hebei (BTH) region, where ozone pollution can even spread into winter. Quantifying each impact of aerosols on ozone in all seasons is urgent for the worsening ozone pollution in the improved aerosol air quality. In this study, we focused on the impact of aerosols on ozone via influencing photolysis rates. The air pollutants were simulated over the Central East China (CEC) in 2018 by using the Weather Research and Forecasting with Chemistry (WRF-Chem) model. By implementing emissions with base years of 2014 and 2018, we quantified the increase in ozone (ΔOzone_photolysis) caused by the decreasing aerosol concentrations (ΔPM2.5) by influencing photolysis rates over the BTH region in all seasons. Furthermore, combined with the ozone observations, the contribution of ΔOzone_photolysis to the total changes in ozone (ΔOzone_total) in all seasons was quantitatively discussed. Our results showed that ΔPM2.5 showed obvious seasonal variations, which PM2.5 decreased more significantly in winter and autumn than in spring and summer, although significant reductions in anthropogenic emissions were observed in all seasons. Consistent seasonal variations were also observed in ΔOzone_photolysis, and the mean increases reached 5.5 μg m-3, 2.6 μg m-3, 1.2 μg m-3, and 1.4 μg m-3 in winter, autumn, spring, spring, and summer, respectively. Compared with ΔOzone_total, ΔOzone_photolysis accounted for 36.3%, 17.2%, 3.5% and 10.6% of ΔOzone_total in winter, autumn, spring, and summer, respectively, suggesting that ΔOzone_photolysis was not the primary contributor to the current changes in ozone over the BTH region. However, the 36.3% contribution to ΔOzone_total in winter suggested that ΔOzone_photolysis is still an important contributor and should not be ignored when discussing the formation of high ozone episodes occurring in winter.
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Affiliation(s)
- Jinhui Gao
- Plateau Atmosphere and Environment Key Laboratory of Sichuan Province, School of Atmospheric Sciences, Chengdu University of Information Technology, Chengdu, China; Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, China; Center for the Oceanic and Atmospheric Science at SUSTech (COAST), Southern University of Science and Technology, Shenzhen, China
| | - Ying Li
- Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, China; Center for the Oceanic and Atmospheric Science at SUSTech (COAST), Southern University of Science and Technology, Shenzhen, China.
| | - Zhouqing Xie
- Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei, China
| | - Bo Hu
- State Key Laboratory of Atmosphere Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
| | - Lili Wang
- State Key Laboratory of Atmosphere Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
| | - Fangwen Bao
- Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, China; Center for the Oceanic and Atmospheric Science at SUSTech (COAST), Southern University of Science and Technology, Shenzhen, China
| | - Shidong Fan
- Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, China; Center for the Oceanic and Atmospheric Science at SUSTech (COAST), Southern University of Science and Technology, Shenzhen, China
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Li X, Bei N, Wu J, Liu S, Wang Q, Tian J, Liu L, Wang R, Li G. The Heavy Particulate Matter Pollution During the COVID-19 Lockdown Period in the Guanzhong Basin, China. JOURNAL OF GEOPHYSICAL RESEARCH. ATMOSPHERES : JGR 2022; 127:e2021JD036191. [PMID: 35600237 PMCID: PMC9111303 DOI: 10.1029/2021jd036191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 04/01/2022] [Accepted: 04/02/2022] [Indexed: 06/15/2023]
Abstract
Nationwide restrictions on human activities (lockdown) in China since 23 January 2020, to control the 2019 novel coronavirus disease pandemic (COVID-19), has provided an opportunity to evaluate the effect of emission mitigation on particulate matter (PM) pollution. The WRF-Chem simulations of persistent heavy PM pollution episodes from 20 January to 14 February 2020, in the Guanzhong Basin (GZB), northwest China, reveal that large-scale emission reduction of primary pollutants has not substantially improved the air quality during the COVID-19 lockdown period. Simultaneous reduction of primary precursors during the lockdown period only decreases the near-surface PM2.5 mass concentration by 11.6% (12.6 μg m-3), but increases ozone (O3) concentration by 9.2% (5.5 μg m-3) in the GZB. The primary organic aerosol and nitrate are the major contributor to the decreased PM2.5 in the GZB, with the reduction of 28.0% and 21.8%, respectively, followed by EC (10.1%) and ammonium (7.2%). The increased atmospheric oxidizing capacity by the O3 enhancement facilitates the secondary aerosol (SA) formation in the GZB, increasing secondary organic aerosol and sulphate by 6.5% and 3.3%, respectively. Furthermore, sensitivity experiments suggest that combined emission reduction of NOX and VOCs following the ratio of 1:1 is conducive to lowering the wintertime SA and O3 concentration and further alleviating the PM pollution in the GZB.
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Affiliation(s)
- Xia Li
- Key Lab of Aerosol Chemistry and Physics, SKLLQGInstitute of Earth Environment, Chinese Academy of SciencesXi'anChina
- University of the Chinese Academy of SciencesBeijingChina
| | - Naifang Bei
- School of Human Settlements and Civil EngineeringXi'an Jiaotong UniversityXi'anChina
| | - Jiarui Wu
- Key Lab of Aerosol Chemistry and Physics, SKLLQGInstitute of Earth Environment, Chinese Academy of SciencesXi'anChina
| | - Suixin Liu
- Key Lab of Aerosol Chemistry and Physics, SKLLQGInstitute of Earth Environment, Chinese Academy of SciencesXi'anChina
| | - Qiyuan Wang
- Key Lab of Aerosol Chemistry and Physics, SKLLQGInstitute of Earth Environment, Chinese Academy of SciencesXi'anChina
| | - Jie Tian
- Key Lab of Aerosol Chemistry and Physics, SKLLQGInstitute of Earth Environment, Chinese Academy of SciencesXi'anChina
| | - Lang Liu
- Key Lab of Aerosol Chemistry and Physics, SKLLQGInstitute of Earth Environment, Chinese Academy of SciencesXi'anChina
| | - Ruonan Wang
- Key Lab of Aerosol Chemistry and Physics, SKLLQGInstitute of Earth Environment, Chinese Academy of SciencesXi'anChina
- University of the Chinese Academy of SciencesBeijingChina
| | - Guohui Li
- Key Lab of Aerosol Chemistry and Physics, SKLLQGInstitute of Earth Environment, Chinese Academy of SciencesXi'anChina
- CAS Center for Excellence in Quaternary Science and Global ChangeXi'anChina
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11
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Liu Y, He G, Chu B, Ma Q, He H. Atmospheric Heterogeneous Reactions on Soot: A Review. FUNDAMENTAL RESEARCH 2022. [DOI: 10.1016/j.fmre.2022.02.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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12
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Feng T, Zhao S, Liu L, Long X, Gao C, Wu N. Nitrous acid emission from soil bacteria and related environmental effect over the North China Plain. CHEMOSPHERE 2022; 287:132034. [PMID: 34526272 DOI: 10.1016/j.chemosphere.2021.132034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 07/27/2021] [Accepted: 08/25/2021] [Indexed: 06/13/2023]
Abstract
Soil bacteria could be one of the important sources for ambient HONO. However, the HONO emission from soil bacteria over North China Plain (NCP) with vast croplands has not yet been evaluated. In this study, high-resolution simulations are created to explore the HONO emission from soil bacteria over NCP and related influences on atmospheric chemistry. Ground measurements of critical air pollutants including O3, HONO, and PM2.5 compositions are incorporated to constrain the model simulations. Results show that abundant HONO is emitted from soil bacteria over NCP during summertime and the emission rate varies dramatically for different areas (about 0.2 kg km-2 d-1 - 2.0 kg km-2 d-1). The HONO emission rate presents clear diurnal cycles with peaks of 1.5 kg km-2 d-1 in the afternoon and valleys of 0.4 kg km-2 d-1 during the early morning hours. The resulting HONO concentration ranges from 0.2 μg m-3 to 1.4 μg m-3, which predominates the total HONO concentration in ambient air, particularly in western NCP. The soil bacteria source can significantly alter the diurnal cycles of ambient HONO and OH concentrations over NCP, but only slightly change O3 and PM2.5 concentrations via participating photochemistry and secondary aerosol formations. These results highlight the pressing need for the involvement of HONO emission from soil bacteria in modeling studies regarding atmospheric chemistry, particularly in rural areas.
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Affiliation(s)
- Tian Feng
- Department of Geography & Spatial Information Techniques, Ningbo University, Ningbo, Zhejiang, 315211, China; Institute of East China Sea, Ningbo University, Ningbo, Zhejiang, 315211, China
| | - Shuyu Zhao
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, Shaanxi, 710061, China
| | - Lang Liu
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, Shaanxi, 710061, China
| | - Xin Long
- School of Environmental Science & Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China
| | - Chao Gao
- Department of Geography & Spatial Information Techniques, Ningbo University, Ningbo, Zhejiang, 315211, China.
| | - Naicheng Wu
- Department of Geography & Spatial Information Techniques, Ningbo University, Ningbo, Zhejiang, 315211, China
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13
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Zhang X, Feng T, Zhao S, Yang G, Zhang Q, Qin G, Liu L, Long X, Sun W, Gao C, Li G. Elucidating the impacts of rapid urban expansion on air quality in the Yangtze River Delta, China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 799:149426. [PMID: 34371396 DOI: 10.1016/j.scitotenv.2021.149426] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 07/29/2021] [Accepted: 07/29/2021] [Indexed: 06/13/2023]
Abstract
Urban expansion not only results in land use transformation, but also introduces extra anthropogenic emissions over the expanded urban areas, which is usually neglected in existing studies. In this study, we consider both the changes in land use categories and added anthropogenic emissions from 2001 to 2018 in the Yangtze River Delta (YRD) which we define as the city of Shanghai and the nearby provinces of Zhejiang, Jiangsu, and Anhui, China and explore the individual and combined impacts of these factors on air pollution using the WRF-Chem model. Calibrated by available observations, the model performs well (IOA (index of agreement) > 0.8) in reproducing the meteorological fields and ambient PM2.5 and O3 concentrations in September 2018. We show that the land use transformation from non-urban to urban and the introduced anthropogenic emissions over new urban areas exert opposite influences on ambient PM2.5 concentrations over YRD, particularly in the expanded urban areas, and the PM2.5 decrease due to land use changes is significantly offset by the increase due to added emissions. The response of ambient O3 concentration to these two factors is highly variable in space, which is dependent on the chemical regime of tropospheric O3 formation and influenced by the chemistry-meteorology feedback. As the total effect, strong increases in O3 concentration occur over the central areas of YRD. These results highlight that it is essential to take into account the additional anthropogenic emissions over expanded urban areas in the assessment of environmental impacts of urban expansion.
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Affiliation(s)
- Xiu Zhang
- Department of Geography & Spatial Information Techniques, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Tian Feng
- Department of Geography & Spatial Information Techniques, Ningbo University, Ningbo, Zhejiang 315211, China; Institute of East China Sea, Ningbo University, Ningbo, Zhejiang 315211, China.
| | - Shuyu Zhao
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, Shaanxi 710061, China
| | - Gang Yang
- Department of Geography & Spatial Information Techniques, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Quan Zhang
- Department of Geography & Spatial Information Techniques, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Gangri Qin
- Department of Geography & Spatial Information Techniques, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Lang Liu
- School of Public Policy and Administration, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, China
| | - Xin Long
- School of Environmental Science & Engineering, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Weiwei Sun
- Department of Geography & Spatial Information Techniques, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Chao Gao
- Department of Geography & Spatial Information Techniques, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Guohui Li
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, Shaanxi 710061, China
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14
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Li X, Bei N, Tie X, Wu J, Liu S, Wang Q, Liu L, Wang R, Li G. Local and transboundary transport contributions to the wintertime particulate pollution in the Guanzhong Basin (GZB), China: A case study. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 797:148876. [PMID: 34311358 DOI: 10.1016/j.scitotenv.2021.148876] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 07/02/2021] [Accepted: 07/02/2021] [Indexed: 06/13/2023]
Abstract
Heavy haze with high levels of fine particulate matters (PM2.5) frequently engulfs the Guanzhong Basin (GZB) in northwestern China during wintertime. Although it is an enclosed basin with a narrow opening to the east, prevailing easterly winds during heavy haze episodes have a large potential to bring air pollutants to the GZB from the two highly polluted neighboring provinces of Shanxi and Henan (SX&HN). The source-oriented WRF-Chem model simulations of a persistent and heavy haze episode that occurred in the GZB from December 6 to 21, 2016, reveal that local emissions dominate PM2.5 concentrations in the GZB, with an average near-surface PM2.5 contribution of about 56.0% during the episode. The transboundary transport of emissions from SX&HN accounts for around 22.2% of the total PM2.5 in the GZB. Furthermore, with the deterioration of the air quality in the GZB from being slightly polluted to severely polluted in terms of hourly PM2.5 concentration, transboundary transport of emissions from SX&HN plays an increasingly important role in the particulate pollution, with the average PM2.5 contribution increasing from 8.0% to 27.5%. Compared with the source-oriented method (SOM), the brute force method (BFM) overestimates the contribution of GZB local emissions and transboundary transport of emissions from SX&HN to the total PM2.5 in the GZB. In addition, the BFM-estimated NH3 contribution of transboundary transport of emissions from SX&HN is negative, indicating the limitation of the BFM in source apportionment. Our results suggest that cooperative emission mitigation strategies with neighboring provinces are beneficial for lowering the particulate pollution in the GZB, particularly under severely polluted conditions.
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Affiliation(s)
- Xia Li
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Naifang Bei
- School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Xuexi Tie
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China
| | - Jairui Wu
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an 710061, China
| | - Suixin Liu
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an 710061, China
| | - Qiyuan Wang
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an 710061, China
| | - Lang Liu
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China
| | - Ruonan Wang
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Guohui Li
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an 710061, China.
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15
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Feng T, Zhao S, Bei N, Liu S, Li G. Increasing atmospheric oxidizing capacity weakens emission mitigation effort in Beijing during autumn haze events. CHEMOSPHERE 2021; 281:130855. [PMID: 34289598 DOI: 10.1016/j.chemosphere.2021.130855] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 05/07/2021] [Accepted: 05/11/2021] [Indexed: 06/13/2023]
Abstract
Although strict mitigation measures have been implemented since 2013 in Beijing-Tianjin-Hebei (BTH), China, air pollution still frequently occurs. Observations reveal that during pollution episodes in autumn, fine particulate matter (PM2.5) concentrations have not decreased, and particularly, ozone (O3) concentrations have increased remarkably from 2013 to 2015 in Beijing. Additionally, a concurrence of O3 and particulate pollution with high secondary aerosol contributions has been observed frequently, indicating high atmospheric oxidizing capacity (AOC) during particulate pollution. The WRF-Chem model simulations show elevated O3 concentrations and high fractions of oxygenated secondary aerosols (OSA) in PM2.5 (0.53-0.73) during the severe pollution period. During daytime there exhibits an AOC-sufficient regime with the persistently high OSA fraction and an AOC-deficient regime with varied OSA fractions, separated by the O3 level of 80 μg m-3. Our results suggest that increasing AOC can considerably weaken the emission mitigation effort by enhancing the secondary aerosol formation.
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Affiliation(s)
- Tian Feng
- Department of Geography & Spatial Information Techniques, Ningbo University, Ningbo, Zhejiang, 315211, China; Institute of East China Sea, Ningbo University, Ningbo, Zhejiang, 315211, China
| | - Shuyu Zhao
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, Shaanxi, 710061, China
| | - Naifang Bei
- School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, China
| | - Suixin Liu
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, Shaanxi, 710061, China
| | - Guohui Li
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, Shaanxi, 710061, China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an, Shaanxi, 710061, China.
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16
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Lolli S, Vivone G. The role of tropospheric ozone in flagging COVID-19 pandemic transmission. BULLETIN OF ATMOSPHERIC SCIENCE AND TECHNOLOGY 2020; 1:551-555. [PMID: 38624568 PMCID: PMC7737909 DOI: 10.1007/s42865-020-00026-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 11/30/2020] [Indexed: 12/04/2022]
Abstract
COVID-19 pandemic outbreak, caused by the SARS-CoV-2 virus, affected millions of people worldwide causing hundreds of thousands of related fatalities. It is crucial to understand why the virus transmission seems to spread more easily in some regions than others. The residuals, with respect to the modeled COVID-19 per-day hospitalized patients in intensive care unit, are correlated to the meteorological and air-pollutant variables in four major metropolitan areas in Italy during a strict lockdown implemented by the Italian government, making the analysis independent from socio-economic factors. The results show that COVID-19 pandemic-related infections are slowed down by higher tropospheric ozone concentrations and eased by the atmospheric particulate. We quantitatively assessed that higher levels of tropospheric ozone, already proven effective against viruses and microbial contaminants, play a role in flagging COVID-19 pandemic transmission. Because the tropospheric ozone production is depending, among others, by air-quality and sunlight, this can explain why the virus is spreading in different ways.
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Affiliation(s)
- S. Lolli
- CNR-IMAA, Instutute of Methodologies for Environmental Analysis, 85050 Tito Scalo, PZ Italy
| | - G. Vivone
- CNR-IMAA, Instutute of Methodologies for Environmental Analysis, 85050 Tito Scalo, PZ Italy
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17
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Feng T, Zhao S, Zhang X, Wang Q, Liu L, Li G, Tie X. Increasing wintertime ozone levels and secondary aerosol formation in the Guanzhong basin, central China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 745:140961. [PMID: 32721619 DOI: 10.1016/j.scitotenv.2020.140961] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 07/09/2020] [Accepted: 07/12/2020] [Indexed: 05/16/2023]
Abstract
The observed near-surface ozone (O3) concentration has been remarkably increasing during recent years in winter in the Guanzhong basin, central China, showing a continuous enhancement of the atmospheric oxidizing capacity (AOC). The impact of such a change in the AOC on secondary aerosol formation, however, has not yet been assessed. In this study, we simulate the formation of O3 and airborne particles in the atmosphere using the WRF-Chem model, in which the AOC is calculated quantitatively, to understand the responses of secondary aerosols to the AOC increase. Meteorological observations, air pollutants including O3, NO2, SO2, CO, and PM2.5 concentrations at ambient monitoring sites, and the main compositions of submicron particulates measured using ACSM are used to constrain the model simulation. The model result shows that the population hourly and postmeridian Ox (=O3 + NO2) concentrations are good indicators for the wintertime AOC in the basin, suggested by the significantly positive correlations between them. Sensitivity experiments present that the AOC changes may exert important influences on fine particle (PM2.5) concentration with an average rate of 1.94 (μg m-3)/(106 cm-3 s-1) for Δ(PM2.5)/Δ(AOC), which is mostly caused by the mass changes in secondary organic aerosol (43%) and nitrate aerosol (40%) and less attributed to the ammonium (11%) and sulfate (6%) components.
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Affiliation(s)
- Tian Feng
- Department of Geography & Spatial Information Techniques, Ningbo University, Ningbo, Zhejiang 315211, China; Institute of East China Sea, Ningbo University, Ningbo, Zhejiang 315211, China.
| | - Shuyu Zhao
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, Shaanxi 710061, China
| | - Xiu Zhang
- Department of Geography & Spatial Information Techniques, Ningbo University, Ningbo, Zhejiang 315211, China
| | - Qiyuan Wang
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, Shaanxi 710061, China
| | - Lang Liu
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, Shaanxi 710061, China
| | - Guohui Li
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, Shaanxi 710061, China
| | - Xuexi Tie
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, Shaanxi 710061, China
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18
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Liu L, Bei N, Hu B, Wu J, Liu S, Li X, Wang R, Liu Z, Shen Z, Li G. Wintertime nitrate formation pathways in the north China plain: Importance of N 2O 5 heterogeneous hydrolysis. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 266:115287. [PMID: 32805595 DOI: 10.1016/j.envpol.2020.115287] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 07/05/2020] [Accepted: 07/21/2020] [Indexed: 06/11/2023]
Abstract
Strict emission control measures have been implemented in the North China Plain (NCP) to improve air quality since 2013. However, heavy particulate matter (PM) pollution still frequently occurs in the region especially during wintertime, and the nitrate contribution to fine PM (PM2.5) has substantially increased in recent several years. Nitrate aerosols, which are formed via nitric acid (HNO3) to balance inorganic cations in the particle phase, have become a major fraction of PM2.5 during wintertime haze events in the NCP. HNO3 is mainly produced through homogeneous (NO2+OH, NO3+VOCs) and heterogeneous pathways (N2O5 heterogeneous hydrolysis) in the atmosphere, but the contribution of the two pathways to the nitrate formation remains elusive. In this study, the Weather Research and Forecasting model with Chemistry (WRF-Chem) was applied to simulate a heavy haze episode from 16 to December 31, 2016 in the North China Plain, and the source-oriented method (SOM) and brute force method (BFM) were both used to evaluate contributions of the heterogeneous pathway to the nitrate formation. The results demonstrated that the near-surface nitrate contributions of the heterogeneous pathway were about 30.8% based on the BFM, and 51.6% based on the SOM, indicating that the BFM might be subject to underestimating importance of the heterogeneous pathway to the nitrate formation. The SOM simulations further showed that the heterogeneous pathway dominated the nighttime HNO3 production in the planetary boundary layer, with an average contribution of 83.0%. Although N2O5 was photolytically liable during daytime, the heterogeneous N2O5 hydrolysis still contributed 10.1% of HNO3, which was caused by substantial attenuation of incident solar radiation by clouds and high PM2.5 mass loading. Our study highlighted the significantly important role of N2O5 heterogeneous hydrolysis in the nitrate formation during wintertime haze days.
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Affiliation(s)
- Lang Liu
- Key Lab of Aerosol Chemistry and Physics, State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an, 710061, China
| | - Naifang Bei
- School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Bo Hu
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China
| | - Jiarui Wu
- Key Lab of Aerosol Chemistry and Physics, State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an, 710061, China
| | - Suixin Liu
- Key Lab of Aerosol Chemistry and Physics, State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an, 710061, China
| | - Xia Li
- Key Lab of Aerosol Chemistry and Physics, State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an, 710061, China
| | - Ruonan Wang
- Key Lab of Aerosol Chemistry and Physics, State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an, 710061, China
| | - Zirui Liu
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China
| | - Zhenxing Shen
- School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Guohui Li
- Key Lab of Aerosol Chemistry and Physics, State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an, 710061, China.
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Xing L, Li G, Pongpiachan S, Wang Q, Han Y, Cao J, Tipmanee D, Palakun J, Aukkaravittayapun S, Surapipith V, Poshyachinda S. Quantifying the contributions of local emissions and regional transport to elemental carbon in Thailand. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 262:114272. [PMID: 32135434 DOI: 10.1016/j.envpol.2020.114272] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 02/24/2020] [Accepted: 02/24/2020] [Indexed: 05/24/2023]
Abstract
We used the Weather Research and Forecasting Model coupled with Chemistry (WRF-Chem) to simulate elemental carbon (EC) concentrations in Thailand in 2017. The goals were to quantify the respective contributions of local emissions and regional transport outside Thailand to EC pollution in Thailand, and to identify the most effective emission control strategy for decreasing EC pollution. The simulated EC concentrations in Chiang Mai, Bangkok, and Phuket were comparable with the observation data. The correlation coefficient between the simulated and observed EC concentrations was 0.84, providing a good basis for evaluating EC sources in Thailand. The simulated mean EC concentration over the whole country was the highest (1.38 μg m-3) in spring, and the lowest (0.51 μg m-3) in summer. We conducted several sensitivity simulations to evaluate EC sources. Local emissions (including anthropogenic and biomass burning emissions) and regional transport outside Thailand contributed 81.2% and 18.8% to the annual mean EC concentrations, respectively, indicating that local sources played the dominant role for EC pollution in Thailand. Among the local sources, anthropogenic emissions (including the industry, power plant, residential, and transportation sectors) and biomass burning contributed 75.1% and 6.1% to the annual mean EC concentrations, respectively. As the anthropogenic emissions dominated the EC pollution, we performed four sensitivity simulations by reducing 30% of the emissions from each of the industry, power plant, residential, and transportation sectors in Thailand. The results indicated that controlling transportation emissions in Thailand was the most effective way in reducing the EC pollution. The 30% reduction of transportation emissions decreased the annual mean EC concentrations by 12.1%. In contrast, 30% reductions of the residential, industry, and power plant emissions caused 8.4%, 6.4%, and 4.0% decreases in the annual mean EC concentrations, respectively. The model results could potentially provide useful information for air pollution control strategies in Thailand.
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Affiliation(s)
- Li Xing
- School of Geography and Tourism, Shaanxi Normal University, Xi'an, 710119, China; Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China.
| | - Guohui Li
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China
| | - Siwatt Pongpiachan
- NIDA Center for Research & Development of Disaster Prevention & Management, School of Social and Environmental Development, National Institute of Development Administration (NIDA), 118 Moo 3, Sereethai Road, Klong-Chan, Bangkapi, Bangkok, 10240, Thailand
| | - Qiyuan Wang
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China
| | - Yongming Han
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China
| | - Junji Cao
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China
| | - Danai Tipmanee
- Faculty of Technology and Environment, Prince of Songkla University Phuket Campus 80 M.1 Kathu, Phuket, 83120, Thailand
| | - Jittree Palakun
- Faculty of Education, Valaya Alongkorn Rajabhat University Under the Royal Patronage (VRU), No. 1 Moo 20, Phaholyothin Road, Klong Luang, Pathumthani, 13180, Thailand
| | - Suparerk Aukkaravittayapun
- National Astronomical Research Institute of Thailand (Public Organization), 260 Moo 4, T. Donkaew, A. Maerim, Chiang-Mai, 50180, Thailand
| | - Vanisa Surapipith
- National Astronomical Research Institute of Thailand (Public Organization), 260 Moo 4, T. Donkaew, A. Maerim, Chiang-Mai, 50180, Thailand
| | - Saran Poshyachinda
- National Astronomical Research Institute of Thailand (Public Organization), 260 Moo 4, T. Donkaew, A. Maerim, Chiang-Mai, 50180, Thailand
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20
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Aerosol-photolysis interaction reduces particulate matter during wintertime haze events. Proc Natl Acad Sci U S A 2020; 117:9755-9761. [PMID: 32300007 DOI: 10.1073/pnas.1916775117] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Aerosol-radiation interaction (ARI) plays a significant role in the accumulation of fine particulate matter (PM2.5) by stabilizing the planetary boundary layer and thus deteriorating air quality during haze events. However, modification of photolysis by aerosol scattering or absorbing solar radiation (aerosol-photolysis interaction or API) alters the atmospheric oxidizing capacity, decreases the rate of secondary aerosol formation, and ultimately alleviates the ARI effect on PM2.5 pollution. Therefore, the synergetic effect of both ARI and API can either aggravate or even mitigate PM2.5 pollution. To test the effect, a fully coupled Weather Research and Forecasting (WRF)-Chem model has been used to simulate a heavy haze episode in North China Plain. Our results show that ARI contributes to a 7.8% increase in near-surface PM2.5 However, API suppresses secondary aerosol formation, and the combination of ARI and API results in only 4.8% net increase of PM2.5 Additionally, API increases the solar radiation reaching the surface and perturbs aerosol nucleation and activation to form cloud condensation nuclei, influencing aerosol-cloud interaction. The results suggest that API reduces PM2.5 pollution during haze events, but adds uncertainties in climate prediction.
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21
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Zhang F, Wang Y, Peng J, Chen L, Sun Y, Duan L, Ge X, Li Y, Zhao J, Liu C, Zhang X, Zhang G, Pan Y, Wang Y, Zhang AL, Ji Y, Wang G, Hu M, Molina MJ, Zhang R. An unexpected catalyst dominates formation and radiative forcing of regional haze. Proc Natl Acad Sci U S A 2020; 117:3960-3966. [PMID: 32041887 PMCID: PMC7049161 DOI: 10.1073/pnas.1919343117] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Although regional haze adversely affects human health and possibly counteracts global warming from increasing levels of greenhouse gases, the formation and radiative forcing of regional haze on climate remain uncertain. By combining field measurements, laboratory experiments, and model simulations, we show a remarkable role of black carbon (BC) particles in driving the formation and trend of regional haze. Our analysis of long-term measurements in China indicates declined frequency of heavy haze events along with significantly reduced SO2, but negligibly alleviated haze severity. Also, no improving trend exists for moderate haze events. Our complementary laboratory experiments demonstrate that SO2 oxidation is efficiently catalyzed on BC particles in the presence of NO2 and NH3, even at low SO2 and intermediate relative humidity levels. Inclusion of the BC reaction accounts for about 90-100% and 30-50% of the sulfate production during moderate and heavy haze events, respectively. Calculations using a radiative transfer model and accounting for the sulfate formation on BC yield an invariant radiative forcing of nearly zero W m-2 on the top of the atmosphere throughout haze development, indicating small net climatic cooling/warming but large surface cooling, atmospheric heating, and air stagnation. This BC catalytic chemistry facilitates haze development and explains the observed trends of regional haze in China. Our results imply that reduction of SO2 alone is insufficient in mitigating haze occurrence and highlight the necessity of accurate representation of the BC chemical and radiative properties in predicting the formation and assessing the impacts of regional haze.
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Affiliation(s)
- Fang Zhang
- College of Global Change and Earth System Science, Beijing Normal University, 100875 Beijing, China
- Department of Atmospheric Sciences, Texas A&M University, College Station, TX 77843
| | - Yuan Wang
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125
| | - Jianfei Peng
- Department of Atmospheric Sciences, Texas A&M University, College Station, TX 77843
| | - Lu Chen
- College of Global Change and Earth System Science, Beijing Normal University, 100875 Beijing, China
| | - Yele Sun
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, 100080 Beijing, China
| | - Lian Duan
- Department of Atmospheric Sciences, Texas A&M University, College Station, TX 77843
- State Environmental Protection Key Lab of Environmental Risk Assessment and Control on Chemical Processes, East China University of Science and Technology, 200237 Shanghai, China
| | - Xinlei Ge
- Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Nanjing University of Information Science and Technology, 210044 Nanjing, China
| | - Yixin Li
- Department of Chemistry, Texas A&M University, College Station, TX 77843
| | - Jiayun Zhao
- Department of Chemistry, Texas A&M University, College Station, TX 77843
| | - Chao Liu
- School of Atmospheric Physics, Nanjing University of Information Science & Technology, 210044 Nanjing, China
| | - Xiaochun Zhang
- State Key Laboratory of Severe Weather, Chinese Meteorological Administration, Chinese Academy of Meteorological Sciences, 100081 Beijing, China
- Key Laboratory of Atmospheric Chemistry, Chinese Meteorological Administration, Chinese Academy of Meteorological Sciences, 100081 Beijing, China
| | - Gen Zhang
- State Key Laboratory of Severe Weather, Chinese Meteorological Administration, Chinese Academy of Meteorological Sciences, 100081 Beijing, China
- Key Laboratory of Atmospheric Chemistry, Chinese Meteorological Administration, Chinese Academy of Meteorological Sciences, 100081 Beijing, China
| | - Yuepeng Pan
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, 100080 Beijing, China
| | - Yuesi Wang
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, 100080 Beijing, China
| | - Annie L Zhang
- Department of Chemistry, College of Natural Sciences, The University of Texas at Austin, Austin, TX 78712
| | - Yuemeng Ji
- Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, School of Environmental Science and Engineering, Institute of Environmental Health and Pollution Control, Guangdong University of Technology, 510006 Guangzhou, China
| | - Gehui Wang
- Key Laboratory of Geographic Information Science of the Ministry of Education, School of Geographic Sciences, East China Normal University, 200241 Shanghai, China
| | - Min Hu
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, 100871 Beijing, China
| | - Mario J Molina
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093
| | - Renyi Zhang
- Department of Atmospheric Sciences, Texas A&M University, College Station, TX 77843;
- Department of Chemistry, Texas A&M University, College Station, TX 77843
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Abstract
With the ground-level ozone pollution problem increasingly prominent in recent years in China, it is particularly important in basic researches on ozone contamination characteristics. In this study, 13 cities in Beijing-Tianjin-Hebei (BTH) area were examined to determine the characteristics of surface ozone (O3) from 2015 to 2018. Due to the photochemical oxidation of ozone precursors (such as nitrogen oxides and carbon monoxide) along with the presence of sunlight and characteristics of local emission sources, the O3 and oxidant (OX) concentrations showed obvious seasonal variation and daily variation. It implicated that the O3 concentrations reached the maximum during summer. The concentrations of O3 were higher at daytime than those measured at nighttime. The ozone weekend effect was estimated by the difference and deviation, which exhibited that the difference between weekday and weekend were related to the concentrations of ozone precursors and PM, vehicle emissions, and solar radiation. Moreover, the O3 concentrations decreased with the increase of other air pollutants by correlation analysis. The ozone pollution was easily formed at light and moderate polluted periods when compared to other air quality levels.
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Bao Z, Chen L, Li K, Han L, Wu X, Gao X, Azzi M, Cen K. Meteorological and chemical impacts on PM 2.5 during a haze episode in a heavily polluted basin city of eastern China. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 250:520-529. [PMID: 31026699 DOI: 10.1016/j.envpol.2019.04.045] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 03/24/2019] [Accepted: 04/08/2019] [Indexed: 06/09/2023]
Abstract
Haze formation involves many interacting factors, such as secondary aerosol formation, unfavourable synoptic conditions and regional transport. The interaction between these factors complicates scientific understanding of the mechanism behind haze formation. In this study, we investigated the factors resulting in haze events in Longyou, a city located in a basin in China. Aerosol samples of PM2.5 were collected for subsequent chemical composition analysis between 11 January and 5 February 2018. The impacts of wind on PM2.5, SO2 and NO2 concentrations were analysed. Besides, the origin of air parcels and potential sources of PM2.5 were analysed by backward trajectory, potential source contribution function (PSCF) and concentration-weighted trajectories (CWT). Among the water-soluble ions identified, NO3- had the highest concentration, with further analysis demonstrating the haze evolution was mainly driven by the reactions involving NO3- formation. The dramatic increase of nitrate is mainly due to the homogeneous reaction of nitric acid with ammonia, while sulfate is likely due to heterogeneous reactions of NO2, SO2 and NH3. The average wind speed was less than 2 m/s during the aerosol sampling period, which could be considered as a stagnant state. Pollutants emitted by industrial area located in the northeast Longyou were probably brought to observation sites by continuous wind from northeast and accumulated gradually. Air parcels originating from the northeast of Zhejiang province also had large effects on haze pollution in Longyou. Together, our results showed that rapid secondary aerosol formation and unfavourable synoptic conditions are the main factors resulting in haze pollution in Longyou.
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Affiliation(s)
- Zhier Bao
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou, 310027, China
| | - Linghong Chen
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou, 310027, China.
| | - Kangwei Li
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou, 310027, China
| | - Lixia Han
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou, 310027, China
| | - Xuecheng Wu
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou, 310027, China
| | - Xiang Gao
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou, 310027, China
| | - Merched Azzi
- CSIRO Energy, PO Box 52, North Ryde, NSW, 1670, Australia
| | - Kefa Cen
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou, 310027, China
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24
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Deng T, Wang T, Wang S, Zou Y, Yin C, Li F, Liu L, Wang N, Song L, Wu C, Wu D. Impact of typhoon periphery on high ozone and high aerosol pollution in the Pearl River Delta region. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 668:617-630. [PMID: 30856571 DOI: 10.1016/j.scitotenv.2019.02.450] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 02/09/2019] [Accepted: 02/28/2019] [Indexed: 06/09/2023]
Abstract
This paper analyzes observation data in the Pearl River Delta (PRD) region from 2012 to 2013, and explores the impact of typhoon periphery on high ozone and high aerosol pollution episodes (double high episodes). Observation analysis show that severe tropical storms to severe typhoons are mainly located in the range of 10°N-30°N, 116°E-135°E when double high episodes occur. Meanwhile, obvious high temperature, low humidity, low wind speed, high actinic flux, high aerosol optical depth (AOD), and high single scattering albedo (SSA) can be observed in double high episodes. The diurnal cycle of the PM2.5 is significant in double high episodes, and the average peak concentration in the afternoon can exceed 90 μg/m3. The diurnal cycle of PM2.5 in non-double high episodes is not significant, and the average value is about 34-39 μg/m3. The ozone peak concentration in double high episodes is 81-103 ppbv, which is about 27-40 ppbv higher than that of non-double high episodes. High correlation can be found between the aerosol and ozone diurnal cycles in double high episodes, and r2 reaches 0.76. In double high episodes, black carbon, nitrate, and sea salt decrease while sulfate, ammonium, secondary organic carbon, and total PM2.5 significantly increase in the afternoon. The growth of PM2.5 in double high episodes is mainly contributed by scattered fine particles from photochemical processes and transmission. The mechanisms that control the double high episodes in the PRD are described below. Ozone and aerosol begin to accumulate under unfavorable meteorological conditions. Via local photochemical processes and external transport, the scattered aerosol increases and leads to an increase in multiple scattering and actinic radiation, which is in turn more favorable for photochemical reaction and further increases the ozone concentration. Meanwhile, high oxidizability promotes the formation of scattered aerosol, creating positive feedback. In addition, the scattered aerosol increases backscattering, which increases the photolysis rate and ozone concentration in the middle and upper boundary layer. Meanwhile, downdraft and turbulence transports high-concentration ozone to the ground.
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Affiliation(s)
- Tao Deng
- School of Atmospheric Sciences, Nanjing University, Nanjing 210023, China; Institute of Tropical and Marine Meteorology, China Meteorological Administration, Guangzhou, China.
| | - Tijian Wang
- School of Atmospheric Sciences, Nanjing University, Nanjing 210023, China.
| | | | - Yu Zou
- Institute of Tropical and Marine Meteorology, China Meteorological Administration, Guangzhou, China
| | - Changqin Yin
- Institute of Tropical and Marine Meteorology, China Meteorological Administration, Guangzhou, China
| | - Fei Li
- Institute of Tropical and Marine Meteorology, China Meteorological Administration, Guangzhou, China
| | - Li Liu
- Institute of Tropical and Marine Meteorology, China Meteorological Administration, Guangzhou, China
| | - Nan Wang
- Institute of Tropical and Marine Meteorology, China Meteorological Administration, Guangzhou, China
| | - Lang Song
- Institute of Tropical and Marine Meteorology, China Meteorological Administration, Guangzhou, China; Institute of Mass Spectrometer and Atmospheric Environment, Jinan University, Guangzhou 510632, China
| | - Cheng Wu
- Institute of Mass Spectrometer and Atmospheric Environment, Jinan University, Guangzhou 510632, China
| | - Dui Wu
- Institute of Tropical and Marine Meteorology, China Meteorological Administration, Guangzhou, China; Institute of Mass Spectrometer and Atmospheric Environment, Jinan University, Guangzhou 510632, China
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25
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Zhu J, Chen Y, Shang J, Zhu T. Effects of air/fuel ratio and ozone aging on physicochemical properties and oxidative potential of soot particles. CHEMOSPHERE 2019; 220:883-891. [PMID: 33395809 DOI: 10.1016/j.chemosphere.2018.12.107] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Revised: 12/12/2018] [Accepted: 12/14/2018] [Indexed: 06/12/2023]
Abstract
Fuel combustion conditions and atmospheric aging processes can affect the physicochemical properties of soot particles, which further change the oxidative potential (OP) of soot. In this study, we generated two soot samples under higher and lower air/fuel ratio (A/F) conditions, and further treated them with ozone (O3) at a level similar to that in the polluted atmosphere. The physicochemical properties and OP values (measured by dithiothreitol (DTT) assay, OPDTT) of fresh and ozonised soot samples were compared to investigate the influences of A/F and O3 aging. Both A/F and O3 aging significantly affected soot physicochemical properties and OPDTT values. Lower A/F was favourable for generating soot particles containing more polycyclic aromatic hydrocarbon (PAH), water-soluble organic carbon (WSOC), and light-absorbing organics, but fewer oxygen-containing groups. After O3 aging, a decline in PAHs and increase in oxygen-containing groups and WSOC were observed in both aged soot samples. In addition, both lower A/F and O3 aging enhanced soot OPDTT values. Soot generated under lower A/F was more sensitive to O3 aging, after which there was a significantly greater change in physicochemical characteristics, in turn contributing substantially to the greater OP increase observed in low-A/F soot.
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Affiliation(s)
- Jiali Zhu
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, and Center for Environment and Health, Peking University, Beijing 100871, PR China
| | - Yueyue Chen
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, and Center for Environment and Health, Peking University, Beijing 100871, PR China
| | - Jing Shang
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, and Center for Environment and Health, Peking University, Beijing 100871, PR China.
| | - Tong Zhu
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, and Center for Environment and Health, Peking University, Beijing 100871, PR China
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26
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Feng T, Bei N, Zhao S, Wu J, Li X, Zhang T, Cao J, Zhou W, Li G. Wintertime nitrate formation during haze days in the Guanzhong basin, China: A case study. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 243:1057-1067. [PMID: 30253296 DOI: 10.1016/j.envpol.2018.09.069] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Revised: 09/11/2018] [Accepted: 09/13/2018] [Indexed: 06/08/2023]
Abstract
In this study, the formation of nitrate aerosol from 16 to 24 December 2015 in the Guanzhong basin, China is simulated using the WRF-Chem model. The predicted near-surface O3, NO2, and fine particulate matters (PM2.5) in the basin and inorganic aerosols and nitrous acid (HONO) in Xi'an are generally in good agreement with the observations. Sensitivity studies show that the heterogeneous HONO sources play an appreciable role in the nitrate formation in the basin, contributing 9.2% of nitrate mass concentrations during heavy haze days. Nitrate formation is also affected by sulfate due to their competition for ammonia, particularly in urban areas. A 50% decrease in SO2 emissions enhances the nitrate concentration by 6.2% during heavy haze days on average in the basin, and a 50% increase in SO2 emission reduces the nitrate concentration by 9.7%. The roles of HONO and sulfate competition in nitrate formation are strongly modulated by ammonia. Agricultural emissions predominate the nitrate level in the basin (93.5%), but the non-agricultural sources cannot substantially influence nitrate formation (3.7%-14.6%). Reducing agricultural emission is an effective control strategy to mitigate nitrate pollution in the basin.
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Affiliation(s)
- Tian Feng
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China; School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi, China; Xi'an Accelerator Mass Spectrometry Center, Xi'an, China
| | - Naifang Bei
- School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Shuyu Zhao
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China
| | - Jiarui Wu
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China
| | - Xia Li
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China
| | - Ting Zhang
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China
| | - Junji Cao
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China; School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Weijian Zhou
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China; Xi'an Accelerator Mass Spectrometry Center, Xi'an, China
| | - Guohui Li
- Key Lab of Aerosol Chemistry and Physics, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China.
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27
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Inverse Relations of PM2.5 and O3 in Air Compound Pollution between Cold and Hot Seasons over an Urban Area of East China. ATMOSPHERE 2017. [DOI: 10.3390/atmos8030059] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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28
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Chu H, Shang J, Jin M, Chen Y, Pan Y, Li Y, Tao X, Cheng Z, Meng Q, Li Q, Jia G, Zhu T, Hao W, Wei X. Comparison of lung damage in mice exposed to black carbon particles and 1,4-naphthoquinone coated black carbon particles. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 580:572-581. [PMID: 28034545 DOI: 10.1016/j.scitotenv.2016.11.214] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 11/30/2016] [Accepted: 11/30/2016] [Indexed: 06/06/2023]
Abstract
Black carbon (BC) is a key component of atmospheric particles and has a significant effect on human health. BC can provide reactive sites and surfaces thus absorb quinones which were primarily generated from fossil fuel combustion and/or atmospheric photochemical conversions of PAHs. Oxidation could change the characteristics of BC and increase its toxicity. The comparison of lung damage in mice exposed to BC and 1,4-NQ-coated BC (1,4NQ-BC) particles is investigated in this study. Mice which were intratracheally instilled with particles have a higher expression of IL-1β, IL-6 and IL-33 in bronchoalveolar lavage fluid (BALF). Also, the IL-6, IL-33 mRNA expression in the lung tissue of mice instilled with 1,4NQ-BC were higher than that of mice instilled with BC. The pathology results showed that the lung tissue of mice instilled with 1,4NQ-BC particles have much more inflammatory cells infiltration than that of mice treated with BC. It is believed that the MAPK and PI3K-AKT pathway might be involved in the 1,4NQ-BC particles caused lung damage. Results indicated that 1,4NQ-BC particles in the atmosphere may cause more damage to health.
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Affiliation(s)
- Hongqian Chu
- Department of Toxicology, School of Public Health, Peking University, Beijing, 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing, 100191, PR China
| | - Jing Shang
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, PR China
| | - Ming Jin
- Department of Toxicology, School of Public Health, Peking University, Beijing, 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing, 100191, PR China
| | - Yueyue Chen
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, PR China
| | - Yao Pan
- Department of Toxicology, School of Public Health, Peking University, Beijing, 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing, 100191, PR China
| | - Yuan Li
- Department of Toxicology, School of Public Health, Peking University, Beijing, 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing, 100191, PR China
| | - Xi Tao
- Department of Toxicology, School of Public Health, Peking University, Beijing, 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing, 100191, PR China
| | - Zhiyuan Cheng
- Department of Toxicology, School of Public Health, Peking University, Beijing, 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing, 100191, PR China
| | - Qinghe Meng
- Department of Toxicology, School of Public Health, Peking University, Beijing, 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing, 100191, PR China
| | - Qian Li
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, PR China; POTEN Environment Group Co., Ltd., Beijing 100082, PR China
| | - Guang Jia
- Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, Beijing 100191, PR China
| | - Tong Zhu
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, PR China
| | - Weidong Hao
- Department of Toxicology, School of Public Health, Peking University, Beijing, 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing, 100191, PR China.
| | - Xuetao Wei
- Department of Toxicology, School of Public Health, Peking University, Beijing, 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing, 100191, PR China.
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29
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Chen J, Jiang S, Liu YR, Huang T, Wang CY, Miao SK, Wang ZQ, Zhang Y, Huang W. Interaction of oxalic acid with dimethylamine and its atmospheric implications. RSC Adv 2017. [DOI: 10.1039/c6ra27945g] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Oxalic acid and dimethylamine are the most common organic acid and base in the atmosphere, and are recognized as significant precursor species in atmospheric new particle formation.
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Affiliation(s)
- Jiao Chen
- Laboratory of Atmospheric Physico-Chemistry
- Anhui Institute of Optics & Fine Mechanics
- Chinese Academy of Sciences
- Hefei
- China
| | - Shuai Jiang
- Laboratory of Atmospheric Physico-Chemistry
- Anhui Institute of Optics & Fine Mechanics
- Chinese Academy of Sciences
- Hefei
- China
| | - Yi-Rong Liu
- Laboratory of Atmospheric Physico-Chemistry
- Anhui Institute of Optics & Fine Mechanics
- Chinese Academy of Sciences
- Hefei
- China
| | - Teng Huang
- Laboratory of Atmospheric Physico-Chemistry
- Anhui Institute of Optics & Fine Mechanics
- Chinese Academy of Sciences
- Hefei
- China
| | - Chun-Yu Wang
- Laboratory of Atmospheric Physico-Chemistry
- Anhui Institute of Optics & Fine Mechanics
- Chinese Academy of Sciences
- Hefei
- China
| | - Shou-Kui Miao
- Laboratory of Atmospheric Physico-Chemistry
- Anhui Institute of Optics & Fine Mechanics
- Chinese Academy of Sciences
- Hefei
- China
| | - Zhong-Quan Wang
- Laboratory of Atmospheric Physico-Chemistry
- Anhui Institute of Optics & Fine Mechanics
- Chinese Academy of Sciences
- Hefei
- China
| | - Yang Zhang
- Laboratory of Atmospheric Physico-Chemistry
- Anhui Institute of Optics & Fine Mechanics
- Chinese Academy of Sciences
- Hefei
- China
| | - Wei Huang
- Laboratory of Atmospheric Physico-Chemistry
- Anhui Institute of Optics & Fine Mechanics
- Chinese Academy of Sciences
- Hefei
- China
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30
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Abstract
Sulfate aerosols exert profound impacts on human and ecosystem health, weather, and climate, but their formation mechanism remains uncertain. Atmospheric models consistently underpredict sulfate levels under diverse environmental conditions. From atmospheric measurements in two Chinese megacities and complementary laboratory experiments, we show that the aqueous oxidation of SO2 by NO2 is key to efficient sulfate formation but is only feasible under two atmospheric conditions: on fine aerosols with high relative humidity and NH3 neutralization or under cloud conditions. Under polluted environments, this SO2 oxidation process leads to large sulfate production rates and promotes formation of nitrate and organic matter on aqueous particles, exacerbating severe haze development. Effective haze mitigation is achievable by intervening in the sulfate formation process with enforced NH3 and NO2 control measures. In addition to explaining the polluted episodes currently occurring in China and during the 1952 London Fog, this sulfate production mechanism is widespread, and our results suggest a way to tackle this growing problem in China and much of the developing world.
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31
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Guo S, Hu M, Lin Y, Gomez-Hernandez M, Zamora ML, Peng J, Collins DR, Zhang R. OH-Initiated Oxidation of m-Xylene on Black Carbon Aging. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:8605-8612. [PMID: 27384756 DOI: 10.1021/acs.est.6b01272] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Laboratory experiments are conducted to investigate aging of size-classified black carbon (BC) particles from OH-initiated oxidation of m-xylene. The variations in the particle size, mass, effective density, morphology, optical properties, hygroscopicity, and activation as cloud condensation nuclei (CCN) are simultaneously measured by a suite of aerosol instruments, when BC particles are exposed to the oxidation products of the OH-m-xylene reactions. The BC aging is governed by the coating thickness (Δrve), which is correlated to the reaction time and initial concentrations of m-xylene and NOx. For an initial diameter of 100 nm and Δrve = 44 nm, the particle size and mass increase by a factor of 1.5 and 10.4, respectively, and the effective density increases from 0.43 to 1.45 g cm(-3) due to organic coating and collapsing of the BC core. The BC particles are fully converted from a highly fractal to nearly spherical morphology for Δrve = 30 nm. The scattering, absorption, and single scattering albedo of BC particles are enhanced accordingly with organic coating. The critical supersaturation for CCN activation is reduced to 0.1% with Δrve = 44 nm. The results imply that the oxidation of m-xylene exhibits larger impacts in modifying the BC particle properties than those for the OH-initiated oxidation of isoprene and toluene.
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Affiliation(s)
- Song Guo
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University , Beijing, 100871, China
| | - Min Hu
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University , Beijing, 100871, China
| | - Yun Lin
- Department of Atmospheric Sciences, Texas A&M University , College Station, Texas 77843, United States
| | - Mario Gomez-Hernandez
- Department of Chemistry, Texas A&M University , College Station, Texas 77843, United States
| | - Misti L Zamora
- Department of Atmospheric Sciences, Texas A&M University , College Station, Texas 77843, United States
| | - Jianfei Peng
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University , Beijing, 100871, China
| | - Donald R Collins
- Department of Atmospheric Sciences, Texas A&M University , College Station, Texas 77843, United States
| | - Renyi Zhang
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University , Beijing, 100871, China
- Department of Atmospheric Sciences, Texas A&M University , College Station, Texas 77843, United States
- Department of Chemistry, Texas A&M University , College Station, Texas 77843, United States
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32
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Sun F, Lun X, Liu X, Mo L, Li R, Zhang H, Chen J, Cao Y, Shi F, Yu X. Analysis of organic and elemental carbon in heating and non-heating periods in four locations of Beijing. ENVIRONMENTAL TECHNOLOGY 2015; 37:121-128. [PMID: 26101900 DOI: 10.1080/09593330.2015.1064170] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The concentrations of elemental carbon (EC) and organic carbon (OC) in PM2.5 atmospheric aerosol were measured at four different sites in Beijing: Beijing Olympic Forest Park (OF), Jiufeng National Forest Park (JF), Beijing Forestry University campus lawn (G), and roads near the Beijing Forestry University (S). The winter heating period concentrations were 30-45% higher than the spring non-heating period. Possible reasons for this could be the severe convective weather in spring due to the temperate monsoon, deposition of PM2.5 to plants in spring, stable atmospheric conditions in winter, and/or a greater number of sources of carbonaceous aerosols in winter. The proportion of total carbon (i.e. EC + OC) in PM2.5 in Beijing is high. The OC/EC value was 2.45 (OF) and 2.39 (JF) in winter and 1.6 (OF) and 1.43 (JF) in spring. These ratios and the high correlation of OC with EC in the winter samples indicate a strong primary source of OC. Eight carbon fractions from the four different sampling locations were analysed, and the OC1-4 values were found to vary considerably. In winter, the OC1 values from all four sites were higher than the spring values. Although there were differences at each site, the percentages of OC2, OC3, EC1-OP, and EC2 were the largest. Secondary organic carbon (SOC) formed during long-range transport from the emission sources to the monitoring sites, and the increase of OC2 and OC3 concentrations could be associated with SOC.
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Affiliation(s)
- Fengbin Sun
- a School of Soil and Water Conservation , Beijing Forestry University , Beijing 100083 , People's Republic of China
- b Zachry Department of Civil Engineering , Texas A&M University , College Station , TX 77843 , USA
| | - Xiaoxiu Lun
- c College of Environmental Science and Engineering , Beijing Forestry University , Beijing 100083 , People's Republic of China
| | - Xuhui Liu
- a School of Soil and Water Conservation , Beijing Forestry University , Beijing 100083 , People's Republic of China
| | - Li Mo
- a School of Soil and Water Conservation , Beijing Forestry University , Beijing 100083 , People's Republic of China
| | - Renna Li
- c College of Environmental Science and Engineering , Beijing Forestry University , Beijing 100083 , People's Republic of China
| | - Hongxia Zhang
- a School of Soil and Water Conservation , Beijing Forestry University , Beijing 100083 , People's Republic of China
| | - Jungang Chen
- a School of Soil and Water Conservation , Beijing Forestry University , Beijing 100083 , People's Republic of China
| | - Yingying Cao
- c College of Environmental Science and Engineering , Beijing Forestry University , Beijing 100083 , People's Republic of China
| | - Fangtian Shi
- d College of Environmental Science and Engineering , Peking University , Beijing 100871 , People's Republic of China
| | - Xinxiao Yu
- a School of Soil and Water Conservation , Beijing Forestry University , Beijing 100083 , People's Republic of China
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33
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In-Situ Aircraft Measurements of the Vertical Distribution of Black Carbon in the Lower Troposphere of Beijing, China, in the Spring and Summer Time. ATMOSPHERE 2015. [DOI: 10.3390/atmos6050713] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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34
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Zhang R, Wang G, Guo S, Zamora ML, Ying Q, Lin Y, Wang W, Hu M, Wang Y. Formation of urban fine particulate matter. Chem Rev 2015; 115:3803-55. [PMID: 25942499 DOI: 10.1021/acs.chemrev.5b00067] [Citation(s) in RCA: 472] [Impact Index Per Article: 52.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Renyi Zhang
- §State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, People's Republic of China
| | | | - Song Guo
- §State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, People's Republic of China
| | | | | | | | | | - Min Hu
- §State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, People's Republic of China
| | - Yuan Wang
- #Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91125, United States
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35
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Asian pollution climatically modulates mid-latitude cyclones following hierarchical modelling and observational analysis. Nat Commun 2015; 5:3098. [PMID: 24448316 DOI: 10.1038/ncomms4098] [Citation(s) in RCA: 129] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 12/12/2013] [Indexed: 11/08/2022] Open
Abstract
Increasing levels of anthropogenic aerosols in Asia have raised considerable concern regarding its potential impact on the global atmosphere, but the magnitude of the associated climate forcing remains to be quantified. Here, using a novel hierarchical modelling approach and observational analysis, we demonstrate modulated mid-latitude cyclones by Asian pollution over the past three decades. Regional and seasonal simulations using a cloud-resolving model show that Asian pollution invigorates winter cyclones over the northwest Pacific, increasing precipitation by 7% and net cloud radiative forcing by 1.0 W m(-2) at the top of the atmosphere and by 1.7 W m(-2) at the Earth's surface. A global climate model incorporating the diabatic heating anomalies from Asian pollution produces a 9% enhanced transient eddy meridional heat flux and reconciles a decadal variation of mid-latitude cyclones derived from the Reanalysis data. Our results unambiguously reveal a large impact of the Asian pollutant outflows on the global general circulation and climate.
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36
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Qiu C, Khalizov AF, Hogan B, Petersen EL, Zhang R. High sensitivity of diesel soot morphological and optical properties to combustion temperature in a shock tube. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:6444-6452. [PMID: 24803287 DOI: 10.1021/es405589d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Carbonaceous particles produced from combustion of fossil fuels have strong impacts on air quality and climate, yet quantitative relationships between particle characteristics and combustion conditions remain inadequately understood. We have used a shock tube to study the formation and properties of diesel combustion soot, including particle size distributions, effective density, elemental carbon (EC) mass fraction, mass-mobility scaling exponent, hygroscopicity, and light absorption and scattering. These properties are found to be strongly dependent on the combustion temperature and fuel equivalence ratio. Whereas combustion at higher temperatures (∼2000 K) yields fractal particles of a larger size and high EC content (90 wt %), at lower temperatures (∼1400 K) smaller particles of a higher organic content (up to 65 wt %) are produced. Single scattering albedo of soot particles depends largely on their organic content, increasing drastically from 0.3 to 0.8 when the particle EC mass fraction decreases from 0.9 to 0.3. The mass absorption cross-section of diesel soot increases with combustion temperature, being the highest for particles with a higher EC content. Our results reveal that combustion conditions, especially the temperature, may have significant impacts on the direct and indirect climate forcing of atmospheric soot aerosols.
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Affiliation(s)
- Chong Qiu
- Department of Chemistry & Industrial Hygiene, University of North Alabama , Florence, Alabama 35632-5049, United States
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37
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Putero D, Landi TC, Cristofanelli P, Marinoni A, Laj P, Duchi R, Calzolari F, Verza GP, Bonasoni P. Influence of open vegetation fires on black carbon and ozone variability in the southern Himalayas (NCO-P, 5079 m a.s.l.). ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2014; 184:597-604. [PMID: 24212180 DOI: 10.1016/j.envpol.2013.09.035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 09/26/2013] [Accepted: 09/27/2013] [Indexed: 06/02/2023]
Abstract
We analysed the variability of equivalent black carbon (BC) and ozone (O3) at the global WMO/GAW station Nepal Climate Observatory-Pyramid (NCO-P, 5079 m a.s.l.) in the southern Himalayas, for evaluating the possible contribution of open vegetation fires to the variability of these short-lived climate forcers/pollutants (SLCF/SLCP) in the Himalayan region. We found that 162 days (9% of the data-set) were characterised by acute pollution events with enhanced BC and O3 in respect to the climatological values. By using satellite observations (MODIS fire products and the USGS Land Use Cover Characterization) and air mass back-trajectories, we deduced that 56% of these events were likely to be affected by emissions from open fires along the Himalayas foothills, the Indian Subcontinent and the Northern Indo-Gangetic Plain. These results suggest that open fire emissions are likely to play an important role in modulating seasonal and inter-annual BC and O3 variability over south Himalayas.
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Affiliation(s)
- D Putero
- ISAC-CNR, Institute for Atmospheric Sciences and Climate, National Research Council, via Gobetti 101, 40129 Bologna, Italy
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38
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Xu W, Zhang R. A theoretical study of hydrated molecular clusters of amines and dicarboxylic acids. J Chem Phys 2013; 139:064312. [DOI: 10.1063/1.4817497] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
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39
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Khalizov AF, Lin Y, Qiu C, Guo S, Collins D, Zhang R. Role of OH-initiated oxidation of isoprene in aging of combustion soot. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:2254-2263. [PMID: 23379649 DOI: 10.1021/es3045339] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We have investigated the contribution of OH-initiated oxidation of isoprene to the atmospheric aging of combustion soot. The experiments were conducted in a fluoropolymer chamber on size-classified soot aerosols in the presence of isoprene, photolytically generated OH, and nitrogen oxides. The evolution in the mixing state of soot was monitored from simultaneous measurements of the particle size and mass, which were used to calculate the particle effective density, dynamic shape factor, mass fractal dimension, and coating thickness. When soot particles age, the increase in mass is accompanied by a decrease in particle mobility diameter and an increase in effective density. Coating material not only fills in void spaces, but also causes partial restructuring of fractal soot aggregates. For thinly coated aggregates, the single scattering albedo increases weakly because of the decreased light absorption and practically unchanged scattering. Upon humidification, coated particles absorb water, leading to an additional compaction. Aging transforms initially hydrophobic soot particles into efficient cloud condensation nuclei at a rate that increases in the presence of nitrogen oxides. Our results suggest that ubiquitous biogenic isoprene plays an important role in aging of anthropogenic soot, shortening its atmospheric lifetime and considerably altering its impacts on air quality and climate.
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Affiliation(s)
- Alexei F Khalizov
- Department of Atmospheric Sciences, Texas A&M University , College Station, Texas, 77843, United States
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40
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Abstract
Heterogeneous reactions of amines have been recently shown to play an important role in the formation and transformation of atmospheric aerosols. This perspective summarizes the latest laboratory progress in the multiphase chemistry of amines. Particular emphasis is given to the contributions of amines to new particle formation, growth of submicron particles, and alteration in the physiochemical properties of pre-existing particles, including hygroscopicity, thermostability, density, phase, and optical properties, from exposure to gaseous amines. The atmospheric implications of the multiphase reactions of amines, including the potential impact on direct and indirect climate forcing of aerosols, and future research directions are discussed.
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Affiliation(s)
- Chong Qiu
- Department of Chemistry, Texas A&M University, College Station, TX 77843, USA
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41
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Key role of organic carbon in the sunlight-enhanced atmospheric aging of soot by O2. Proc Natl Acad Sci U S A 2012; 109:21250-5. [PMID: 23236134 DOI: 10.1073/pnas.1212690110] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Soot particles are ubiquitous in the atmosphere and have important climatic and health effects. The aging processes of soot during long-range transport result in variability in its morphology, microstructure, and hygroscopic and optical properties, subsequently leading to the modification of soot's climatic and health effects. In the present study the aging process of soot by molecular O(2) under simulated sunlight irradiation is investigated. Organic carbon components on the surface of soot are found to play a key role in soot aging and are transformed into oxygen-containing organic species including quinones, ketones, aldehydes, lactones, and anhydrides. These oxygen-containing species may become adsorption centers of water and thus enhance the cloud condensation nuclei and ice nuclei activities of soot. Under irradiation of 25 mW·cm(-2), the apparent rate constants (k(1,obs)) for loss or formation of species on soot aged by 20% O(2) were larger by factors of 1.5-3.5 than those on soot aged by 100 ppb O(3). Considering the abundance of O(2) in the troposphere and its higher photoreactivity rate, the photochemical oxidation by O(2) under sunlight irradiation should be a very important aging process for soot.
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42
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Qiu C, Khalizov AF, Zhang R. Soot aging from OH-initiated oxidation of toluene. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:9464-9472. [PMID: 22853850 DOI: 10.1021/es301883y] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We have conducted laboratory experiments to investigate the impacts of secondary organic aerosol formation on soot properties from OH-initiated oxidation of toluene. Monodisperse soot particles are exposed to the oxidation products of the OH-toluene reaction in an environmental chamber, and variations in particle size, mass, organic mass faction, morphology, effective density, hygroscopicity, and optical properties are simultaneously determined by an integrated aerosol analytical system. The thickness of the organic coating, correlated to reaction time and initial reactant concentrations, is shown to largely govern the particle properties. With the development of organic coating, the soot core is changed from a highly fractal to compact form, evident from the measured effective density and dynamic shape factor. The organic coating increases the particle hygroscopicity, and further exposure of coated soot to elevated relative humidity results in a more spherical particle. The single scattering albedo and scattering and absorption cross sections are also enhanced with the organic coating. Our results suggest that the oxidation products of anthropogenic pollutants alter the composition and properties of soot particles and lead to increased particle density, hygroscopicity, and optical properties, considerably enhancing their impacts on air quality, climate forcing, and human health.
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Affiliation(s)
- Chong Qiu
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
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43
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Attenuation of ultraviolet radiation reaching the surface due to atmospheric aerosols in Guangzhou. ACTA ACUST UNITED AC 2012. [DOI: 10.1007/s11434-012-5172-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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44
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Xu W, Zhang R. Theoretical Investigation of Interaction of Dicarboxylic Acids with Common Aerosol Nucleation Precursors. J Phys Chem A 2012; 116:4539-50. [DOI: 10.1021/jp301964u] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Wen Xu
- Department of Chemistry and ‡Department of Atmospheric Sciences, Texas A&M University, College Station, Texas 77840, United States
| | - Renyi Zhang
- Department of Chemistry and ‡Department of Atmospheric Sciences, Texas A&M University, College Station, Texas 77840, United States
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45
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Qiu C, Zhang R. Physiochemical properties of alkylaminium sulfates: hygroscopicity, thermostability, and density. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:4474-4480. [PMID: 22417685 DOI: 10.1021/es3004377] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Although heterogeneous interaction of amines has been recently shown to play an important role in the formation and growth of atmospheric aerosols, little information is available on the physicochemical properties of aminium sulfates. In this study, the hygroscopicity, thermostability, and density of alkylaminium sulfates (AASs) have been measured by an integrated aerosol analytical system including a tandem differential mobility analyzer and an aerosol particle mass analyzer. AAS aerosols exhibit monotonic size growth at increasing RH without a well-defined deliquescence point. Mixing of ammonium sulfate (AS) with AASs lowers the deliquescence point corresponding to AS. Particles with AASs show comparable or higher thermostability than that of AS. The density of AASs is determined to be 1.2-1.5 g cm(-3), and an empirical model is developed to predict the density of AASs on the basis of the mole ratio of alkyl carbons to total sulfate. Our results reveal that the heterogeneous uptake of amines on sulfate particles may considerably alter the aerosol properties. In particular, the displacement reaction of alkylamines with ammonium sulfate aerosols leads to a transition from the crystalline to an amorphorous phase and an improved water uptake, considerably enhancing their direct and indirect climate forcing.
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Affiliation(s)
- Chong Qiu
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
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46
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Lal V, Khalizov AF, Lin Y, Galvan MD, Connell BT, Zhang R. Heterogeneous Reactions of Epoxides in Acidic Media. J Phys Chem A 2012; 116:6078-90. [DOI: 10.1021/jp2112704] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Vinita Lal
- Department of Atmospheric Sciences and ‡Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Alexei F. Khalizov
- Department of Atmospheric Sciences and ‡Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Yun Lin
- Department of Atmospheric Sciences and ‡Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Maria D. Galvan
- Department of Atmospheric Sciences and ‡Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Brian T. Connell
- Department of Atmospheric Sciences and ‡Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Renyi Zhang
- Department of Atmospheric Sciences and ‡Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
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47
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Zhang R, Khalizov A, Wang L, Hu M, Xu W. Nucleation and growth of nanoparticles in the atmosphere. Chem Rev 2011; 112:1957-2011. [PMID: 22044487 DOI: 10.1021/cr2001756] [Citation(s) in RCA: 469] [Impact Index Per Article: 36.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Renyi Zhang
- Department of Atmospheric Sciences and Department of Chemistry, Center for Atmospheric Chemistry and Environment, Texas A&M University, College Station, Texas 77843, USA.
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48
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Fernandes AP, Alves CA, Gonçalves C, Tarelho L, Pio C, Schimdl C, Bauer H. Emission factors from residential combustion appliances burning Portuguese biomass fuels. ACTA ACUST UNITED AC 2011; 13:3196-206. [DOI: 10.1039/c1em10500k] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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49
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Li G, Wang Y, Lee KH, Diao Y, Zhang R. Impacts of aerosols on the development and precipitation of a mesoscale squall line. ACTA ACUST UNITED AC 2009. [DOI: 10.1029/2008jd011581] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Xue H, Khalizov AF, Wang L, Zheng J, Zhang R. Effects of dicarboxylic acid coating on the optical properties of soot. Phys Chem Chem Phys 2009; 11:7869-75. [PMID: 19727494 DOI: 10.1039/b904129j] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Soot is a major component of atmospheric aerosols responsible for absorption of visible solar radiation. Internal mixing of soot with transparent materials can enhance its ability to absorb and scatter light, resulting in a larger role of soot in climate forcing. We have investigated the absorption and scattering of visible light (532 nm) by soot aerosol internally mixed with succinic and glutaric acids using a combination of a cavity ring-down spectrometer and an integrating nephelometer. The measurements were performed for flame-generated soot aerosol with well-characterized morphology and mixing state in the particle size range from 155 to 320 nm. Thin coatings of dicarboxylic acids on soot aggregates (with a mass fraction of 0.1-0.4) enhance significantly light scattering (up to 3.8 fold) and slightly light absorption (less than 1.2 fold). Cycling the coated soot aerosol through high relative humidity (humidified to 90% RH and then dried to 5% RH) promotes further increase in light absorption and scattering for soot internally mixed with glutaric acid, but not for soot mixed with succinic acid. The larger effect of glutaric acid on light absorption and scattering is caused by the irreversible restructuring of soot aggregates induced by the coating material. Our results indicate that the enhancement in the optical properties of soot by transparent coatings is strongly related to the ability of the coating materials to change the morphology of soot aggregates.
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Affiliation(s)
- Huaxin Xue
- Department of Atmospheric Sciences and Department of Chemistry, Texas A&M University, College Station, TX 77843, USA
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