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Chu B, Zhang S, Liu J, Ma Q, He H. Significant concurrent decrease in PM 2.5 and NO 2 concentrations in China during COVID-19 epidemic. J Environ Sci (China) 2021; 99:346-353. [PMID: 33183713 PMCID: PMC7328636 DOI: 10.1016/j.jes.2020.06.031] [Citation(s) in RCA: 79] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 06/23/2020] [Accepted: 06/23/2020] [Indexed: 05/20/2023]
Abstract
The strict control measures and social lockdowns initiated to combat COVID-19 epidemic have had a notable impact on air pollutant concentrations. According to observation data obtained from the China National Environmental Monitoring Center, compared to levels in 2019, the average concentration of NO2 in early 2020 during COVID-19 epidemic has decreased by 53%, 50%, and 30% in Wuhan city, Hubei Province (Wuhan excluded), and China (Hubei excluded), respectively. Simultaneously, PM2.5 concentration has decreased by 35%, 29%, and 19% in Wuhan, Hubei (Wuhan excluded), and China (Hubei excluded), respectively. Less significant declines have also been found for SO2 and CO concentrations. We also analyzed the temporal variation and spatial distribution of air pollutant concentrations in China during COVID-19 epidemic. The decreases in PM2.5 and NO2 concentrations showed relatively consistent temporal variation and spatial distribution. These results support control of NOx to further reduce PM2.5 pollution in China. The concurrent decrease in NOx and PM2.5 concentrations resulted in an increase of O3 concentrations across China during COVID-19 epidemic, indicating that coordinated control of other pollutants is needed.
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Yao L, Fan X, Yan C, Kurtén T, Daellenbach KR, Li C, Wang Y, Guo Y, Dada L, Rissanen MP, Cai J, Tham YJ, Zha Q, Zhang S, Du W, Yu M, Zheng F, Zhou Y, Kontkanen J, Chan T, Shen J, Kujansuu JT, Kangasluoma J, Jiang J, Wang L, Worsnop DR, Petäjä T, Kerminen VM, Liu Y, Chu B, He H, Kulmala M, Bianchi F. Unprecedented Ambient Sulfur Trioxide (SO 3) Detection: Possible Formation Mechanism and Atmospheric Implications. ENVIRONMENTAL SCIENCE & TECHNOLOGY LETTERS 2020; 7:809-818. [PMID: 33195731 PMCID: PMC7659313 DOI: 10.1021/acs.estlett.0c00615] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 09/24/2020] [Accepted: 09/25/2020] [Indexed: 05/20/2023]
Abstract
Sulfur trioxide (SO3) is a crucial compound for atmospheric sulfuric acid (H2SO4) formation, acid rain formation, and other atmospheric physicochemical processes. During the daytime, SO3 is mainly produced from the photo-oxidation of SO2 by OH radicals. However, the sources of SO3 during the early morning and night, when OH radicals are scarce, are not fully understood. We report results from two field measurements in urban Beijing during winter and summer 2019, using a nitrate-CI-APi-LTOF (chemical ionization-atmospheric pressure interface-long-time-of-flight) mass spectrometer to detect atmospheric SO3 and H2SO4. Our results show the level of SO3 was higher during the winter than during the summer, with high SO3 levels observed especially during the early morning (∼05:00 to ∼08:30) and night (∼18:00 to ∼05:00 the next day). On the basis of analysis of SO2, NO x , black carbon, traffic flow, and atmospheric ions, we suggest SO3 could be formed from the catalytic oxidation of SO2 on the surface of traffic-related black carbon. This previously unidentified SO3 source results in significant H2SO4 formation in the early morning and thus promotes sub-2.5 nm particle formation. These findings will help in understanding urban SO3 and formulating policies to mitigate secondary particle formation in Chinese megacities.
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Deng C, Fu Y, Dada L, Yan C, Cai R, Yang D, Zhou Y, Yin R, Lu Y, Li X, Qiao X, Fan X, Nie W, Kontkanen J, Kangasluoma J, Chu B, Ding A, Kerminen VM, Paasonen P, Worsnop DR, Bianchi F, Liu Y, Zheng J, Wang L, Kulmala M, Jiang J. Seasonal Characteristics of New Particle Formation and Growth in Urban Beijing. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:8547-8557. [PMID: 32609510 DOI: 10.1021/acs.est.0c00808] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Understanding the atmospheric new particle formation (NPF) process within the global range is important for revealing the budget of atmospheric aerosols and their impacts. We investigated the seasonal characteristics of NPF in the urban environment of Beijing. Aerosol size distributions down to ∼1 nm and H2SO4 concentration were measured during 2018-2019. The observed formation rate of 1.5 nm particles (J1.5) is significantly higher than those in the clean environment, e.g., Hyytiälä, whereas the growth rate is not significantly different. Both J1.5 and NPF frequency in urban Beijing show a clear seasonal variation with maxima in winter and minima in summer, while the observed growth rates are generally within the same range around the year. We show that ambient temperature is a governing factor driving the seasonal variation of J1.5. In contrast, the condensation sink and the daily maximum H2SO4 concentration show no significant seasonal variation during the NPF periods. In all four seasons, condensation of H2SO4 and (H2SO4)n(amine)n clusters contributes significantly to the growth rates in the sub-3 nm size range, whereas it is less important for the observed growth rates of particles above 3 nm. Therefore, other species are always needed for the growth of larger particles.
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Wang M, Kong W, Marten R, He XC, Chen D, Pfeifer J, Heitto A, Kontkanen J, Dada L, Kürten A, Yli-Juuti T, Manninen HE, Amanatidis S, Amorim A, Baalbaki R, Baccarini A, Bell DM, Bertozzi B, Bräkling S, Brilke S, Murillo LC, Chiu R, Chu B, De Menezes LP, Duplissy J, Finkenzeller H, Carracedo LG, Granzin M, Guida R, Hansel A, Hofbauer V, Krechmer J, Lehtipalo K, Lamkaddam H, Lampimäki M, Lee CP, Makhmutov V, Marie G, Mathot S, Mauldin RL, Mentler B, Müller T, Onnela A, Partoll E, Petäjä T, Philippov M, Pospisilova V, Ranjithkumar A, Rissanen M, Rörup B, Scholz W, Shen J, Simon M, Sipilä M, Steiner G, Stolzenburg D, Tham YJ, Tomé A, Wagner AC, Wang DS, Wang Y, Weber SK, Winkler PM, Wlasits PJ, Wu Y, Xiao M, Ye Q, Zauner-Wieczorek M, Zhou X, Volkamer R, Riipinen I, Dommen J, Curtius J, Baltensperger U, Kulmala M, Worsnop DR, Kirkby J, Seinfeld JH, El-Haddad I, Flagan RC, Donahue NM. Rapid growth of new atmospheric particles by nitric acid and ammonia condensation. Nature 2020; 581:184-189. [PMID: 32405020 PMCID: PMC7334196 DOI: 10.1038/s41586-020-2270-4] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 03/17/2020] [Indexed: 11/08/2022]
Abstract
A list of authors and their affiliations appears at the end of the paper New-particle formation is a major contributor to urban smog1,2, but how it occurs in cities is often puzzling3. If the growth rates of urban particles are similar to those found in cleaner environments (1-10 nanometres per hour), then existing understanding suggests that new urban particles should be rapidly scavenged by the high concentration of pre-existing particles. Here we show, through experiments performed under atmospheric conditions in the CLOUD chamber at CERN, that below about +5 degrees Celsius, nitric acid and ammonia vapours can condense onto freshly nucleated particles as small as a few nanometres in diameter. Moreover, when it is cold enough (below -15 degrees Celsius), nitric acid and ammonia can nucleate directly through an acid-base stabilization mechanism to form ammonium nitrate particles. Given that these vapours are often one thousand times more abundant than sulfuric acid, the resulting particle growth rates can be extremely high, reaching well above 100 nanometres per hour. However, these high growth rates require the gas-particle ammonium nitrate system to be out of equilibrium in order to sustain gas-phase supersaturations. In view of the strong temperature dependence that we measure for the gas-phase supersaturations, we expect such transient conditions to occur in inhomogeneous urban settings, especially in wintertime, driven by vertical mixing and by strong local sources such as traffic. Even though rapid growth from nitric acid and ammonia condensation may last for only a few minutes, it is nonetheless fast enough to shepherd freshly nucleated particles through the smallest size range where they are most vulnerable to scavenging loss, thus greatly increasing their survival probability. We also expect nitric acid and ammonia nucleation and rapid growth to be important in the relatively clean and cold upper free troposphere, where ammonia can be convected from the continental boundary layer and nitric acid is abundant from electrical storms4,5.
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Chen T, Liu J, Liu Y, Ma Q, Ge Y, Zhong C, Jiang H, Chu B, Zhang P, Ma J, Liu P, Wang Y, Mu Y, He H. Chemical characterization of submicron aerosol in summertime Beijing: A case study in southern suburbs in 2018. CHEMOSPHERE 2020; 247:125918. [PMID: 31978659 DOI: 10.1016/j.chemosphere.2020.125918] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 12/14/2019] [Accepted: 01/13/2020] [Indexed: 06/10/2023]
Abstract
Atmospheric particulate matters have a crucial impact on climate change, visibility and human health. In this study, a detailed characteristic of summertime PM1 was real-time measured in south suburb of Beijing from 16th August to 16th September 2018. Averaged PM1 concentration of 24.1 ± 18.0 μg m-3 was observed, consisting of OM (50.8%), SO42- (16.0%), BC (13.2%), NO3- (10.2%), NH4+ (9.2%), and Cl- (0.6%). There was an accumulation mode with a peak diameter of ∼500 nm for all the species (except BC), and OM was additionally characterized by a smaller mode of <100 nm. Elemental analysis of OM showed that the diurnal variations of H/C, O/C, N/C, and S/C were correlated to the photochemical and aqueous-phase process. Four organic factors including one hydrocarbon-like (HOA) and three oxygenated (LO-OOA, SV-OOA and MO-OOA) organic aerosol factors were identified by positive matrix factorization (PMF) analysis. The contributions of these factors varied with PM1 concentration and their average values were 31%, 30%, 14%, and 25%, respectively. Contribution of HOA was RH-independent but decreased with the increasing PM1 concentration, while OOA factors were a combined result of RH and Ox (=O3+NO2), revealing the important role of photochemical and aqueous-phase process in OA evolution. The contribution of SV-OOA with the highest S/C increased significantly with RH, indicating a certain number of S-containing organics. Our results also showed that secondary OA was the dominant species, as well as increased with the pollution level, implicating VOCs and NOx should be controlled to relieve the secondary OA pollution.
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Zhang P, Chen T, Liu J, Chu B, Ma Q, Ma J, He H. Impacts of Mixed Gaseous and Particulate Pollutants on Secondary Particle Formation during Ozonolysis of Butyl Vinyl Ether. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:3909-3919. [PMID: 32108486 DOI: 10.1021/acs.est.9b07650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
To clarify how coexisting atmospheric pollutants affect secondary organic aerosol (SOA) formation, we investigated the effects of mixed gaseous pollutants (CO and SO2) and mixed organic-inorganic (MOI) particles on SOA formation during n-butyl vinyl ether (BVE) ozonolysis. Higher CO levels (90 ppm) were found to significantly change the chemical composition of SOA (prompting monomers while reducing oligomer formation) without causing much change in the overall SOA mass. Based on the positive matrix factorization (PMF) analysis, heterogeneous chemical conversions between preformed and newly formed SOA were the major pathways of SOA formation in the presence of MOI particles. Furthermore, MOI particles had an enhancing effect on SOA formation at 1% relative humidity (RH) but a negligible effect at higher RH (10 and 55%). The enhancing effect was attributed to the formation of multifunctional products resulting from high functionalization of preformed and newly formed SOA. The negligible effect observed was ascribed to the cleavage of unstable oligomers as a result of the reversible oligomerization of preformed and newly formed SOA. Even so, MOI particles could still affect the composition of newly formed SOA. These results highlight the need to account for the significant effect of mixed gaseous and particulate pollutants on both SOA constituents and their evolution.
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Wang Y, Gao W, Wang S, Song T, Gong Z, Ji D, Wang L, Liu Z, Tang G, Huo Y, Tian S, Li J, Li M, Yang Y, Chu B, Petäjä T, Kerminen VM, He H, Hao J, Kulmala M, Wang Y, Zhang Y. Contrasting trends of PM2.5 and surface-ozone concentrations in China from 2013 to 2017. Natl Sci Rev 2020; 7:1331-1339. [PMID: 34692161 PMCID: PMC8288972 DOI: 10.1093/nsr/nwaa032] [Citation(s) in RCA: 155] [Impact Index Per Article: 38.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 02/18/2020] [Accepted: 02/19/2020] [Indexed: 11/14/2022] Open
Abstract
Although much attention has been paid to investigating and controlling air pollution in China, the trends of air-pollutant concentrations on a national scale have remained unclear. Here, we quantitatively investigated the variation of air pollutants in China using long-term comprehensive data sets from 2013 to 2017, during which Chinese government made major efforts to reduce anthropogenic emission in polluted regions. Our results show a significant decreasing trend in the PM2.5 concentration in heavily polluted regions of eastern China, with an annual decrease of ∼7% compared with measurements in 2013. The measured decreased concentrations of SO2, NO2 and CO (a proxy for anthropogenic volatile organic compounds) could explain a large fraction of the decreased PM2.5 concentrations in different regions. As a consequence, the heavily polluted days decreased significantly in corresponding regions. Concentrations of organic aerosol, nitrate, sulfate, ammonium and chloride measured in urban Beijing revealed a remarkable reduction from 2013 to 2017, connecting the decreases in aerosol precursors with corresponding chemical components closely. However, surface-ozone concentrations showed increasing trends in most urban stations from 2013 to 2017, which indicates stronger photochemical pollution. The boundary-layer height in capital cities of eastern China showed no significant trends over the Beijing–Tianjin–Hebei, Yangtze River Delta and Pearl River Delta regions from 2013 to 2017, which confirmed the reduction in anthropogenic emissions. Our results demonstrated that the Chinese government was successful in the reduction of particulate matter in urban areas from 2013 to 2017, although the ozone concentration has increased significantly, suggesting a more complex mechanism of improving Chinese air quality in the future.
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Kaspar B, Thomsen G, Hsieh C, Do J, Solano S, Chu B, Barkho B, Fugere M, Kaufmann P, Foust K, Kaspar A, L'Italien J, Sproule D, Feltner D, Chung W, Burghes A, McGovern V, Hevner R, Conces M, Mendell J. O.24Biodistribution of onasemnogene abeparvovec (AVXS-101) DNA, mRNA, and SMN protein in human tissue. Neuromuscul Disord 2019. [DOI: 10.1016/j.nmd.2019.06.307] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Chen T, Chu B, Ge Y, Zhang S, Ma Q, He H, Li SM. Enhancement of aqueous sulfate formation by the coexistence of NO 2/NH 3 under high ionic strengths in aerosol water. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 252:236-244. [PMID: 31153028 DOI: 10.1016/j.envpol.2019.05.119] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 04/27/2019] [Accepted: 05/14/2019] [Indexed: 06/09/2023]
Abstract
Current air quality models usually underestimate the concentration of ambient air sulfate, but the cause of this underestimation remains unclear. One reason for the underestimation is that the sulfate formation mechanism in the models is incomplete, and does not adequately consider the impact of the synergistic effects of high concentrations of multiple pollutants on sulfate formation. In this work, the roles of gaseous NO2, NH3 and solution ionic strength in the formation of sulfate in the aqueous phase were quantitatively investigated using a glass reactor and a 30 m3 smog chamber, separately. The results showed that sulfate formation was enhanced to different degrees in the presence of gas-phase NO2, NH3 and their coexistence as solutes in both liquid solution and aerosol water. NH3 enhances the aqueous oxidation of SO2 by NO2 mainly by accelerating the uptake of SO2 through increased solubility. More importantly, we found that high ionic strength in aerosol water could significantly accelerate the aqueous oxidation of SO2, resulting in unexpectedly high S(VI) formation rates. We estimate that under severe haze conditions, heterogeneous oxidation of SO2 by NO2 on aerosols may be much shorter than that through gas phase oxidation by OH, aided by high ionic strengths in aerosols. Considering the existence of complex air pollution conditions with high concentrations of NO2, NH3 and aerosol water, as expected in typical urban and suburban settings, the sulfate formation mechanisms revealed in the present work should be incorporated into air quality models to improve the prediction of sulfate concentrations.
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Zhang P, Chen T, Liu J, Liu C, Ma J, Ma Q, Chu B, He H. Impacts of SO 2, Relative Humidity, and Seed Acidity on Secondary Organic Aerosol Formation in the Ozonolysis of Butyl Vinyl Ether. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:8845-8853. [PMID: 31298843 DOI: 10.1021/acs.est.9b02702] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Alkyl vinyl ethers are widely used as fuel additives. Despite this, their atmospheric chemistry and secondary organic aerosol (SOA) formation potentials are still not well-known under complex pollution conditions. In this work, we examined the impact of SO2, relative humidity (RH), and particle acidity on the formation and oxidation state (OSc) of SOA from butyl vinyl ether (BVE) ozonolysis. Increasing SO2 concentration produced a notable promotion of SOA formation and OSc due to the significant increase in H2SO4 particles and formation of more highly oxidized components. Increased RH in the presence of SO2 appeared to promote, suppress, and dominate the formation and OSc of SOA in the dry range (1-10%), low RH range (10-42%), and moderate RH range (42-64%), respectively. This highlights the importance of competition between H2O and SO2 in reacting with the stabilized Criegee intermediate in BVE ozonolysis at ambient RH. Increased particle acidity mainly contributed to the change in chemical composition of BVE-dominated SOA but not to SOA formation. The results presented here extend previous analysis of BVE-derived SOA and further aid our understanding of SOA formation potential of BVE ozonolysis under highly complex pollution conditions.
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Zhang S, Xing J, Sarwar G, Ge Y, He H, Duan F, Zhao Y, He K, Zhu L, Chu B. Parameterization of heterogeneous reaction of SO 2 to sulfate on dust with coexistence of NH 3 and NO 2 under different humidity conditions. ATMOSPHERIC ENVIRONMENT (OXFORD, ENGLAND : 1994) 2019; 208:133-140. [PMID: 31186616 PMCID: PMC6559380 DOI: 10.1016/j.atmosenv.2019.04.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Sulfate plays an important role in atmospheric haze in China, which has received considerable attention in recent years. Various types of parameterization methods and heterogeneous oxidation rates of SO2 have been used in previous studies. However, properly representing heterogeneous sulfate formation in air quality models remains a big challenge. In this study, we quantified the heterogeneous oxidation reaction using experimental results that approximate the haze conditions in China. Firstly, a series of experiments were conducted to investigate the heterogeneous uptake of SO2 with different relative humidity (RH) levels and the presence of NH3 and NO2 on natural dust surfaces. Then the uptake coefficients for heterogeneous oxidation of SO2 to sulfate at different RH under NH3 and NO2coexistence were parameterized based on the experimental results and implemented in the Community Multiscale Air Quality modeling system (CMAQ). Simulation results suggested that this new parameterization improved model performance by 6.6% in the simulation of wintertime sulfate concentrations for Beijing. The simulated maximum growth rate of SO4 2- during a heavy pollution period increased from 0.97 μg m-3 h-1 to 10.11 μg m-3 h-1. The heterogeneous oxidation of SO2 in the presence of NH3 contributed up to 23% of the sulfate concentration during heavy pollution periods.
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Chen T, Liu Y, Chu B, Liu C, Liu J, Ge Y, Ma Q, Ma J, He H. Differences of the oxidation process and secondary organic aerosol formation at low and high precursor concentrations. J Environ Sci (China) 2019; 79:256-263. [PMID: 30784449 DOI: 10.1016/j.jes.2018.11.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 11/15/2018] [Accepted: 11/16/2018] [Indexed: 05/16/2023]
Abstract
Current atmospheric quality models usually underestimate the level of ambient secondary organic aerosol (SOA), one of the possible reasons is that the precursors at different concentrations may undergo different oxidation processes and further affect SOA formation. Therefore, there is a need to perform more chamber studies to disclose the influence. In this work, SOA formation over a wide range of initial precursor concentrations (tens of ppb to hundreds of ppb levels) was investigated in a 30 m3 indoor smog chamber, and mainly through the analysis of multiple generations of VOCs detected from HR-ToF-PTRMS to expound the difference in the oxidation process between low and high precursor concentrations. Compared to high initial concentrations, gas-phase intermediates formed at low concentrations had a higher intensity by about one order of magnitude, and the low-volatility compounds also had a higher formation potential due to the competition between semi-volatile intermediates and precursors with oxidants. In addition, the formed SOA was more oxidized with higher f44 value (0.14 ± 0.02) and more relevant to real atmosphere than that formed at high concentrations. This work should help to deeply understand SOA formation and improve the performance of air quality models for SOA simulation.
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Ma Q, Wang L, Chu B, Ma J, He H. Contrary Role of H2O and O2 in the Kinetics of Heterogeneous Photochemical Reactions of SO2 on TiO2. J Phys Chem A 2019; 123:1311-1318. [DOI: 10.1021/acs.jpca.8b11433] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Zhang W, Tong S, Ge M, An J, Shi Z, Hou S, Xia K, Qu Y, Zhang H, Chu B, Sun Y, He H. Variations and sources of nitrous acid (HONO) during a severe pollution episode in Beijing in winter 2016. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 648:253-262. [PMID: 30118938 DOI: 10.1016/j.scitotenv.2018.08.133] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 08/06/2018] [Accepted: 08/10/2018] [Indexed: 06/08/2023]
Abstract
HONO is an important precursor of OH radical and plays a key role in atmospheric chemistry, but its source and formation mechanism remain uncertain, especially during complex atmospheric pollution processes. In this study, HONO mixing ratios were measured by a custom-made instrument during a severe pollution event from 16 to 23 December 2016, at an urban area of Beijing. The measurement was divided into three periods: I (haze), II (severe haze) and III (clean), according to the levels of PM2.5. This pollution episode was characterized by high levels of NO (75 ± 39 and 94 ± 40 ppbV during periods I and II, respectively) and HONO (up to 10.7 ppbV). During the nighttime, the average heterogeneous conversion frequency during the two haze periods were estimated to be 0.0058 and 0.0146 h-1, and it was not the important way to form HONO. Vehicle emissions contributed 52% (±16)% and 40% (±18)% to ambient HONO at nighttime during periods I and II. The contribution of homogeneous reaction of NO with OH should be reconsidered under high-NOx conditions and could be noticeable to HONO sources during this pollution event. Furthermore, HONO was positively correlated with PM2.5 during periods I and II, suggesting a potential chemical link between HONO and haze particles.
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Yang W, Ma Q, Liu Y, Ma J, Chu B, Wang L, He H. Role of NH3 in the Heterogeneous Formation of Secondary Inorganic Aerosols on Mineral Oxides. J Phys Chem A 2018; 122:6311-6320. [DOI: 10.1021/acs.jpca.8b05130] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Liu J, Chu B, Chen T, Liu C, Wang L, Bao X, He H. Secondary Organic Aerosol Formation from Ambient Air at an Urban Site in Beijing: Effects of OH Exposure and Precursor Concentrations. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:6834-6841. [PMID: 29775300 DOI: 10.1021/acs.est.7b05701] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Secondary organic aerosol (SOA) is an important component of atmospheric fine particles (PM2.5), while the key factors controlling SOA formation in ambient air remain poorly understood. In this work, the SOA formation in Beijing urban ambient air was investigated using an oxidation flow reactor (OFR) with high concentrations of OH radicals. The SOA formation potential increased significantly with the increase of ambient PM2.5 concentration during the observation. The optimum ambient exposure time, which is the aging time equivalent to atmospheric oxidation (with similar OH exposure) associated with the peak SOA formation, varied between 2 and 4 days in this study. The OA enhancement in this study was much higher than that of developed countries under different environmental conditions. The higher OA enhancement is probably due to the higher concentrations of volatile organic compounds (VOCs) in the urban air of Beijing. This might also have occurred because fragmentation did not dominate in the oxidation of OA, and did not result in negative OA enhancement on highly polluted days compared to relatively clean days with similar exposure time. These results suggested that under typical ambient conditions, high concentrations of VOC precursors might contribute to sustained organic aerosol growth and long duration haze events in Beijing.
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Ma J, Chu B, Liu J, Liu Y, Zhang H, He H. NO x promotion of SO 2 conversion to sulfate: An important mechanism for the occurrence of heavy haze during winter in Beijing. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 233:662-669. [PMID: 29121601 DOI: 10.1016/j.envpol.2017.10.103] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 10/23/2017] [Accepted: 10/25/2017] [Indexed: 06/07/2023]
Abstract
In this study, concentrations of NOx, SO2, O3 and fine particles (PM2.5) were measured at three monitoring stations in Beijing during 2015. For extreme haze episodes during 25 Nov. - 3 Dec. 2015, observation data confirmed that high concentrations of NOx promoted the conversion of SO2 to sulfate. Annual data confirmed that this is an important mechanism for the occurrence of heavy haze during winter in Beijing. Furthermore, in situ perturbation experiments in a potential aerosol mass (PAM) reactor were carried out at Shengtaizhongxin (STZX) station during both clean and polluted days. The concentrations of SO42-, NH4+, NO3- and organic aerosol were positively related to the concentration of added NO2. These results provide definitive evidence that NO2 can promote the conversion of SO2 to sulfate. At the same time, we found that NO2 can promote the formation of NH4+ and organic compounds in the aerosols. Our results illustrate that strengthened controls of nitrogen oxides is a key step in reducing the fine particles level in China.
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Tong S, Hou S, Zhang Y, Chu B, Liu Y, He H, Zhao P, Ge M. Exploring the nitrous acid (HONO) formation mechanism in winter Beijing: direct emissions and heterogeneous production in urban and suburban areas. Faraday Discuss 2017; 189:213-30. [PMID: 27081740 DOI: 10.1039/c5fd00163c] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Continuous measurements of nitrous acid (HONO) were performed from December 12 to December 22, 2015 in both urban and suburban areas of Beijing to study the formation mechanism of HONO. The measurement campaign in both sites included a clean-haze-clean transformation process. HONO concentrations showed similar variations in the two sites, while they were always higher in the urban area. Moreover, correlations of HONO with NOx, NO2, NO, PM2.5 and relative humidity (RH) were studied to explore possible HONO formation pathways, and the contributions of direct emissions, heterogeneous reactions, and homogeneous reactions were also calculated. This showed that HONO in urban and suburban areas underwent totally different formation procedures, which were affected by meteorological conditions, PM2.5 concentrations, direct emissions, homogeneous reactions and heterogeneous reactions. PM2.5 concentrations and RH would influence the NO2 conversion efficiency. Heterogeneous reactions of NO2 were more efficient in suburban areas and in clean periods while direct emissions and homogeneous reactions contributed more in urban areas and in polluted periods when the concentrations of NOx and NO were at a high level.
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Niu H, Li K, Chu B, Su W, Li J. Heterogeneous Reactions between Toluene and NO 2 on Mineral Particles under Simulated Atmospheric Conditions. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:9596-9604. [PMID: 28728409 DOI: 10.1021/acs.est.7b00194] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Heterogeneous reactions between organic and inorganic gases with aerosols are important for the study of smog occurrence and development. In this study, heterogeneous reactions between toluene and NO2 with three atmospheric mineral particles in the presence or absence of UV light were investigated. The three mineral particles were SiO2, α-Fe2O3, and BS (butlerite and szmolnokite). In a dark environment, benzaldehyde was produced on α-Fe2O3. For BS, nitrotoluene and benzaldehyde were obtained. No aromatic products were produced in the absence of NO2 in the system. In the presence of UV irradiation, benzaldehyde was detected on the SiO2 surface. Identical products were produced in the presence and absence of UV light over α-Fe2O3 and BS. UV light promoted nitrite to nitrate on mineral particles surface. On the basisi of the X-ray photoelectron spectroscopy (XPS) results, a portion of BS was reduced from Fe3+ to Fe2+ with the adsorption of toluene or the reaction with toluene and NO2. Sulfate may play a key role in the generation of nitrotoluene on BS particles. From this research, the heterogeneous reactions between organic and inorganic gases with aerosols that occur during smog events will be better understood.
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Chu B, Liggio J, Liu Y, He H, Takekawa H, Li SM, Hao J. Influence of metal-mediated aerosol-phase oxidation on secondary organic aerosol formation from the ozonolysis and OH-oxidation of α-pinene. Sci Rep 2017; 7:40311. [PMID: 28059151 PMCID: PMC5216392 DOI: 10.1038/srep40311] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 12/02/2016] [Indexed: 12/12/2022] Open
Abstract
The organic component is the most abundant fraction of atmospheric submicron particles, while the formation mechanisms of secondary organic aerosol (SOA) are not fully understood. The effects of sulfate seed aerosols on SOA formation were investigated with a series of experiments carried out using a 9 m3 smog chamber. The presence of FeSO4 or Fe2(SO4)3 seed aerosols decreased SOA yields and increased oxidation levels in both ozonolysis and OH-oxidation of α-pinene compared to that in the presence of ZnSO4 or (NH4)2SO4. These findings were explained by metal-mediated aerosol-phase oxidation of organics: reactive radicals were generated on FeSO4 or Fe2(SO4)3 seed aerosols and reacted further with the organic mass. This effect would help to explain the high O/C ratios of organics in ambient particles that thus far cannot be reproduced in laboratory and model studies. In addition, the gap in the SOA yields between experiments with different seed aerosols was more significant in OH-oxidation experiments compared to ozonolysis experiments, while the gap in estimated O/C ratios was less obvious. This may have resulted from the different chemical compositions and oxidation levels of the SOA generated in the two systems, which affect the branching ratio of functionalization and fragmentation during aerosol oxidation.
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Ge Y, Liu Y, Chu B, He H, Chen T, Wang S, Wei W, Cheng S. Ozonolysis of Trimethylamine Exchanged with Typical Ammonium Salts in the Particle Phase. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:11076-11084. [PMID: 27626464 DOI: 10.1021/acs.est.6b04375] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Alkylamines contribute to both new particle formation and brown carbon. The toxicity of particle-phase amines is of great concern in the atmospheric chemistry community. Degradation of particulate amines may lead to secondary products in the particle phase, which are associated with changes in the adverse health impacts of aerosols. In this study, O3 oxidation of particulate trimethylamine (TMA) formed via heterogeneous uptake of TMA by (NH4)2SO4, NH4HSO4, NH4NO3 and NH4Cl, was investigated with in situ attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and proton transfer reaction mass spectrometry (PTR-MS). HCOOH, HCHO, CH3N═CH2, (CH3)2NCHO, CH3NO2, CH3N(OH)CHO, CH3NHOH and H2O were identified as products on all the substrates based upon IR (one-dimensional IR and two-dimensional correlation infrared spectroscopy), quantum chemical calculation and PTR-MS results. A reaction mechanism was proposed to explain the observed products. This work demonstrates that oxidation might be a degradation pathway of particulate amines in the atmosphere. This will aid in understanding the fate of particulate amines formed by nucleation and heterogeneous uptake and their potential health impacts during atmospheric aging.
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Machin G, Chu B. High-quality blackbody sources for infrared thermometry and thermography between −40 and 1000°C. IMAGING SCIENCE JOURNAL 2016. [DOI: 10.1080/13682199.2000.11784341] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Chu B, Lu MQ, Wu MQ, Shi L, Fu LN, Gao S, Fang LJ, Xiang QQ, Bao L. [Clinical characteristics of bone disease in multiple myeloma and clinical significance of monitoring bone metabolic markers]. ZHONGHUA YI XUE ZA ZHI 2016; 96:1424-9. [PMID: 27266350 DOI: 10.3760/cma.j.issn.0376-2491.2016.18.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
OBJECTIVE To observe the clinical characteristics of bone disease in patients with multiple myeloma (MM) and the clinical significance of monitoring bone metabolic markers. METHODS The data of 178 MM cases newly diagnosed in Beijing Ji Shui Tan Hospital from January 2009 to June 2014 were reviewed to analysis the types and classification of bone disease and to observe the clinical characteristics of patients with different grades of bone disease. The levels of bone metabolic markers total procollagen type Ⅰ N-terminal peptide (tPINP) and β C-terminal telopeptide of type Ⅰ collagen (β-CTX) were monitored regularly in the two years following treatment in 66 cases. RESULTS (1) Among the 178 newly diagnosed MM cases, 167 cases complained of pain in bones on first visit, 35 cases combined with hypercalcemia, 83 cases combined with osteoporosis, 154 cases combined with osteolytic bone destruction, and 73 cases combined with pathologic fracture. The most common osteolytic location was the spine. The most common fracture sites was the spine. (2) According to bone disease grading, the 178 cases were divided into group A (bone grade 0-2, n=51) and group B(bone grade 3-4, n=127). There were no significant differences between group A and group B in gender, median age, therapeutic effect/ineffec, median overall survival, median progress-free survival, mean serum lactic dehydrogenase, mean albumin, urine light chains and serum creatinine(all P>0.05). Compared with group A, group B had lower hemoglobin level[(99.78±29.93)vs (108.84±29.30) g/L], and higher blood calcium level[(2.47±0.40)vs (2.30±0.29) mmol/L], serum β2-microglobuin level[(6.04±4.84)vs (4.12±3.97)mg/L], and bone marrow plasma cells percentage(33.30%±24.87% vs 23.51%±22.67%)(all P<0.05). (3) Before treatment, the levels of β-CTX and tPINP in patients of group B(n=47) were higher than those in group A(n=19)(median 0.78 vs 0.42 μg/L, 60.95 vs 43.47 μg/L, both P<0.05). The ratio of β-CTX /tPINP in group B was higher than that in group A (median 0.017 vs 0.012, P<0.05). After chemotherapy for 3 months, there were no differences in the level of tPINP compared with that before treatment in both group A and group B (both P>0.05), the level of β-CTX decreased significantly compared with that before treatment in both groups(median 0.16 vs 0.42 μg/L, 0.26 vs 0.78 μg/L, both P<0.05); the ratio of β-CTX /tPINP decreased significantly compared with that before treatment in both group A and in group B(median 0.008 vs 0.012, 0.011 vs 0.017, both P<0.05). There were no differences in the level of β-CTX, tPINP and β-CTX/tPINP ratio after treatment for 6 months, 1 year and 2 years compared with that after 3 months in both group A and group B (all P>0.05). (4)All patients were divided into two groups according to the therapeutic effect: effective group included patients who reach the effect of partial remission or better remission(n=48), while ineffective group included patients who did not reach the effect of partial remission(n=18). Before treatment there were no differences in the level of β-CTX, tPINP and β-CTX/tPINP ratio between the effective groupand the ineffective group (all P>0.05). After chemotherapy for 3 months, there were no differences in the level of tPINP compared with that before treatment in both effective group and ineffective group (all P>0.05), but the level of β-CTX decreased significantly compared with that before treatment both in effective group and ineffective group (median 0.24 vs 0.60 μg/L, 0.44 vs 0.95 μg/L, both P<0.05). The ratio of β-CTX /tPINP decreased significantly compared with that before treatment both in effective group and ineffective group (median 0.005 vs 0.012, 0.005 vs 0.011, both P<0.05). There were no differences in the level of β-CTX, tPINP and β-CTX/tPINP ratio after treatment for 6 months, 1 year and 2 years compared with that for 3 months both in effective group and ineffective group (all P>0.05). CONCLUSIONS Pain in bones, osteolysis and pathological fracture are the most common clinical manifestations in myeloma-related bone disease. The severity of bone disease can reflect the tumor load, but may not affect the therapeutic effect and the overall survival. The bone metabolic markers tPINP and β-CTX can be used to evaluate the severity of myeloma-related bone disease at diagnosis and to monitor the effect of treatment for bone disease.
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Espinosa-Jeffrey A, Arrazola RA, Chu B, Taniguchi A, Barajas SM, Bokhoor P, Garcia J, Feria-Velasco A, de Vellis J. Trophic factors intervention regenerates the nestin-expressing cell population in a model of perinatal excitotoxicity: Implications for perinatal brain injury and prematurity. INTEGRATIVE MOLECULAR MEDICINE 2016; 3:703-715. [PMID: 35558521 PMCID: PMC9094396 DOI: 10.15761/imm.1000228] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We previously showed that TSC1 (a combination of transferrin and IGF-1) is a potent inductor of myelinogenesis in myelin deficient rats and in demyelinated adult mice. More recently, we demonstrated that regeneration of oligodendrocyte progenitors and myelin are possible with a single dose of TSC1 in a mouse model of Premature birth. Here, using the same mouse model of perinatal white matter damage due to glutamate excitotoxicity (GME), we tested the hypothesis that regeneration of endogenous nestin-expressing neural progenitors improves the outcome of prematurity. Treatments: N-methyl-D-aspartate (NMDA), saline, NMDA+TSC1 together or NMDA followed byTSC1 3 days later, were stereotaxically delivered into the corpus callosum of P4 mouse pups. Fluorescence analysis showed an intense enrichment of nestin-expressing cells in groups injected with NMDA+TSC1 from which many were generated by proliferation. Moreover, when TSC1 was injected three days after the primary insult it was still able to reduce ventricular enlargement and extensively rescue nestin-expressing progenitors. Cells co-expressing the proliferation marker Ki67, CNPase and faint nestin label were more abundant in groups injected with MNDA+TSC1 at 35 days after injection. Stereological analysis showed that the number of nestin-expressing cells in the sub-ventricular zone correlated inversely with the volume of the ventricle. A delayed administration of TSC1 after excitotoxicity reduced ventriculomegaly but not as much as, when NMDA and TSC1 were injected simultaneously. Thus, the earliest TSC1 was administered, the more tissue was rescued as shown by reduced ventriculomegaly. Astrocytes responded to GME by upregulating the expression of estrogen receptor and this expression was attenuated in the presence of TSC1 suggesting a decreased inflammation and a lesser need for estrogen-mediated central nervous system (CNS) neuroprotection.
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Prates R, Racowsky C, Fox J, Chu B, Munne S. Simultaneous analysis of preimplantation genetic diagnosis (PGD) for fragile X syndrome (FXS) and array CGH (aCGH): advantages of selecting a PGD strategy with comprehensive diagnosis. Fertil Steril 2016. [DOI: 10.1016/j.fertnstert.2015.12.094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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