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arXiv 2021年

作者： Sugimoto, Satoshi Umeno, Ken Deparment of Applied Mathematics and Physics Graduate School of Informatics Kyoto University

We study a stochastic behavior of aerosols by the non-equilibrium statistical mechanics approach using the analytical approach of the Langevin equation. We firstly show that superdiffusion can possibly occur right after the emission, which may be attributed to the physical mechanism of the outbreak of the COVID-19 pandemic. We also provide clear evidence of the least required distance to prevent infections occurred by aerosols. In particular, the required distance to prevent aerosol infections is derived to be about 42 m when we assume Cauchy distribution as an initial velocity distribution. This fact implies that due to superdiffusion the aerosol infection can occur even far away from a long distance as compared to the previous considerations. © 2021, CC0.

关键词： aerosols

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aerosols and carbonaceous and nitrogenous compounds emitted during the combustion of dead shrubs according to twigs' diameter and combustion phases

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FIRE SAFETY JOURNAL 2020年 113卷 102988-000页

作者： Barboni, T. Leonelli, L. Santoni, P-A Tihay-Felicelli, V Univ Cors CNRS UMR 6134 SPE Campus GrimaldiBP 52 F-20250 Corte France

Smoke from forest fires is hazardous to health and can result in losses of respiratory function and vision. The knowledge of the chemical constituents in such smoke is an important objective. In this study, leaves and branches and twigs of Cistus Monspeliensis were burned with a cone calorimeter and the emitted smoke was analysed by non-dispersive infrared (NDIR) spectroscopy, He-Ne laser method, Fourier-transform infrared (FTIR) spectroscopy, and automated thermal-desorption-gas-chromatography/mass-spectrometry (ATD-GC/MS). These techniques were used during various combustion phases: prior to ignition and during flaming and glowing phases. The influence of branch diameter on chemical composition was examined. Analysis of the smoke reveals the presence of CO2, H2O, CO, aerosols, CH4, NO, and other gases in smaller proportions, as well as non-methane organic compounds (NMOCs). 96% of the carbon present in the fuel was found in the emitted smoke. CO2 is the gas mainly emitted and its level is independent of the diameter of the cistus branch burned. It is mainly emitted in the flaming phase, unlike CO, which is emitted during the glowing phase. aerosols are emitted principally during the pre-ignition stage. The mass loss is higher during the flaming phase than during the glowing one because the burning occurs under well-ventilated condition. During the glowing phase, the mass loss is only due to the char oxidation. The calculation of the modified combustion efficiency confirms those operating conditions.

关键词： Smoke emission Emission factor Gases VOC Combustion phases aerosols

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Radiative Forcing and Health Impact of aerosols and Ozone in China as the Consequence of Clean Air Actions over 2012-2017

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GEOPHYSICAL RESEARCH LETTERS 2019年第21期46卷 12511-12519页

作者： Dang, Ruijun Liao, Hong Chinese Acad Sci Inst Atmospher Phys State Key Lab Atmospher Boundary Layer Phys & Atm Beijing Peoples R China Univ Chinese Acad Sci Beijing Peoples R China Nanjing Univ Informat Sci & Technol Sch Environm Sci & Engn Joint Int Res Lab Climate & Environm Change Collaborat Innovat Ctr Atmospher Environm & Equip Nanjing Jiangsu Peoples R China

We applied the chemical transport model GEOS-Chem to examine the changes in aerosols and tropospheric O-3 in China from 2012-2017 and the associated radiative forcing and health impact. Simulated surface layer concentrations and column burdens of aerosols and O-3 were evaluated by comparing with ground-based and satellite-retrieved measurements. Between 2012 and 2017, simulated annual mean concentrations of PM2.5 decreased by 21.0%, while O-3 increased by 11.9% over eastern China (20-45 degrees N, 105-122.5 degrees E). Changes in aerosols and O-3 over 2012-2017 jointly exerted a positive radiative forcing of 1.26 W/m(2) over eastern China, which was dominated by the less cooling from PM2.5 reductions (1.18 W/m(2)). The Global Exposure Mortality Model predicted 268.3 (247.3-291.6) thousand (9.6%) fewer deaths in eastern China in 2017 relative to 2012. These results suggest an appreciable health benefit and a potential warming as a consequence of clean air actions.

关键词： aerosols

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Be-7 and Pb-210 in Fallout and aerosols in 2000 - 2016 in Central Europe - Deposition Velocity and Dependence on Meteorological Parameters

SSRN

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SSRN 2021年

作者： Zalewska, Tamara Biernacik, Dawid Institute of Meteorology and Water Management National Research Institute Waszyngtona 42 Gdynia81-1342 Poland

The main aim of the research was to determine the transport and the deposition velocity of 7Be and 210Pb based on a vast database including the results of 7Be and 210Pb measurements in aerosol and fallout samples carried out at several stations located throughout Poland in the period from 1998 to 2016. The concentrations of 7Be and 210Pb in the precipitation showed an unequivocal downward trend with the seasonal changes with the maximum values in the summer period. The same relationships occurred in the case of the deposition rate, the average values of which were 0.7 cm s-1 in the case of 7Be and 0.5 cm s-1 in the case of 210Pb. A strong, statistically significant dependence of the deposition rate on the amount of dust was demonstrated, whereby a 10µg m-3 decrease in dust increases the 7Be deposition rate by 0.1 cm s-1. The reduction of the carrier particles concentrations reduces the share of dry deposition in favour of the increase in the precipitation convection share, which is much more significant for the transport of both isotopes to the surface. Research on the dependence on meteorological parameters has shown that the concentrations of 7Be in fallout and aerosol samples and 210Pb in fallout increase with increasing temperature, indicating a significant share of convection processes in isotope transport. The concentrations of 210Pb in aerosols did not show any significant statistical changes in time. Their maximum values were in the winter period, indicating an additional source of this isotope related to combustion processes in the heating season. The studies confirmed the dominant role of convective precipitation and large-scale precipitation processes in the elution of 7Be from the atmosphere by showing a strong dependence of this isotope concentration in the total precipitation on the total precipitation (r = 0.618). © 2021, The Authors. All rights reserved.

关键词： aerosols

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Development and qualification of a VH-TDMA for the study of pure aerosols

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AEROSOL SCIENCE AND TECHNOLOGY 2019年第2期53卷 120-132页

作者： Oxford, Christopher R. Rapp, Charles M. Wang, Yang Kumar, Purushottam Watson, Daniel Portelli, Julianna L. Sussman, Eric A. Dhawan, Steven Jiang, Jingkun Williams, Brent J. Washington Univ Dept Energy Environm & Chem Engn 1 Brookings DrCampus Box 1180 St Louis MO 63130 USA Brookhaven Natl Lab Environm & Climate Sci Dept Upton NY 11973 USA Indian Inst Technol Gandhinagar Discipline Chem Engn Pala 382355 Gujarat India Case Western Reserve Univ Dept Chem & Biomol Engn Cleveland OH 44106 USA Tsinghua Univ Sch Environm Beijing 100084 Peoples R China

We create and qualify a Volatility and Hygroscopicity Tandem Differential Mobility Analyzer (VH-TDMA) for the study of aerosols. This VH-TDMA measures size distributions, volatility, and hygroscopicity and includes an auxiliary conditioner that allows quick connection to other external aerosol conditioners. The differential mobility analyzers are not temperature controlled, allowing the surrounding environment to influence the measurement conditions, and this is fully accounted for when measuring aerosol volatility and hygroscopicity. For the volatility conditioner, the VH-TDMA uses a 15 m coil of tubing in an oven to evaporate aerosol samples at elevated temperatures. We measured several single component model aerosols to qualify the differential mobility particle sizer (DMPS) channel and each of the conditioners: hygroscopicity and volatility. Due to insufficient power supply calibration in this study, the TDMA channel is limited to particle sizes greater than 70 nm. The DMPS channel was able to reproduce ammonium sulfate size distributions when compared to common scanning mobility particle sizers. For hygroscopicity, the standard deviation in the measured ammonium sulfate growth factors was 0.03 over a 4-h experiment. From this data, the TDMA has an observed relative humidity error of +/- 0.6% with manufacturer reported error of +/- 1.2% relative humidity. The volatility channel reproduced the previously published saw tooth pattern of room temperature saturation vapor pressures from atomized C3-C9 diacids. The maximum percent difference in room temperature saturation vapor pressure was approximately 80%. The enthalpy of sublimation derived from the diacids increased monotonically (except for suberic acid) and resembled measurements from mass effusion techniques.

关键词： aerosols

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Evidence of precedent wind role on controlling PM1 wet scavenging of aerosols during monsoon rain events

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ATMOSPHERIC ENVIRONMENT 2019年第Mar.期201卷 265-277页

作者： Yang, L. Pandithurai, G. Chate, D. M. Rao, P. S. P. Waghmare, V Iyer, U. Indian Inst Trop Meteorol Pune Maharashtra India

The role of precedent winds over fine mode (0.05-1 mu m) aerosols during 2016 rainfall event is studied in this manuscript. Here, we show that concomitant wind actions influence over scavenging process during south-west monsoon rainfall over Mahabaleshwar at High Altitude Cloud Physics Laboratory (HACPL-17.56 degrees N, 73.4 degrees E, site altitude-1373m). During monsoon, PM1/PM10 mass ratios revealed dominance of PM1 for June, July, August, September and October as similar to 80%, 90%, 98%, 97%, and 95% respectively. Fine mode aerosols and rains associated with lower precedent wind speeds similar to 2 m/s were found to enhance the scavenging from similar to 60 to 90% based (before minus after rainfall event) on Aerosol Chemical Speciation Monitor (ACSM) mass (SO42-, NO3-) concentrations. Similarly, before rain CCN number concentration and wind speed exhibited, similar to 0.34 correlation coefficient (at 0.99% significance level) suggesting a viable decrease in CCN concentration due to increased wind speed. It was also observed that ventilation coefficients maxima values similar to 12500 m(2) /s to be negatively correlated with before rain minima Cloud Condensation Nuclei (CCN) concentrations falling down to similar to 1000 cm(-3) . Moreover, three major sources such as vehicular, thunder lightning frequency and long range transport were found to control the monthly volume weighted average concentrations of rainwater. The mass (SO42- , NO3-) concentration for the monthly volume weighted averages with relatively high rainwater concentrations of NO3- (9.02 +/- 4.71 mu g/m(3)) and SO42-(11.61 +/- 6.71 mu g/m(3)) for the month of June, with minimum of NO3-(4.11 +/- 1.16 mu g/m(3)) and SO42- (9.91 +/- 7.07 mu g/m(3)) were seen in month of July and September respectively. However, October (16.45 +/- 5.17 mu g/m(3), 8.08 +/- 3.46 mu g/m(3)) displayed an increase in both SO42- and NO3- rainwater concentration due to long range and increased local sources scavenging process

关键词： Rainwater Scavenging aerosols Monsoon PM1 Sources

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Water-Soluble Brown Carbon in Atmospheric aerosols from Godavari (Nepal), a Regional Representative of South Asia

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ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019年第7期53卷 3471-3479页

作者： Wu, Guangming Ram, Kirpa Fu, Pingqing Wang, Wan Zhang, Yanlin Liu, Xiaoyan Stone, Elizabeth A. Pradhan, Bidya Banmali Dangol, Pradeep Man Panday, Arnico K. Wan, Xin Bai, Zhipeng Kang, Shichang Zhang, Qianggong Cong, Zhiyuan Chinese Acad Sci Inst Tibetan Plateau Res Key Lab Tibetan Environm Changes & Land Surface P Beijing 100101 Peoples R China Banaras Hindu Univ Inst Environm & Sustainable Dev Varanasi 221005 Uttar Pradesh India Tianjin Univ Inst Surface Earth Syst Sci Tianjin 300072 Peoples R China Chinese Res Inst Environm Sci State Key Lab Environm Criteria & Risk Assessment Beijing 100012 Peoples R China Nanjing Univ Informat Sci & Technol Yale NUIST Ctr Atmospher Environm Nanjing 210044 Jiangsu Peoples R China Univ Iowa Dept Chem Iowa City IA 52246 USA Int Ctr Integrated Mt Dev Khumaltar 009771 Lalitpur Nepal Chinese Acad Sci Northwest Inst Ecoenvironm & Resources State Key Lab Cryospher Sci Lanzhou 730000 Gansu Peoples R China Chinese Acad Sci Ctr Excellence Tibetan Plateau Earth Sci Beijing 100101 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China

Brown carbon (BrC) has recently emerged as an important light-absorbing aerosol. This study provides interannual and seasonal variations in light absorption properties, chemical composition, and sources of water-soluble BrC (WS-BrC) based on PM10 samples collected in Godavari, Nepal, from April 2012 to May 2014. The mass absorption efficiency of WS-BrC at 365 nm (MAE(365)) shows a clear seasonal variability, with the highest MAE(365) of 1.05 +/- 0.21 m(2) g(-1) in premonsoon season and the lowest in monsoon season (0.59 +/- 0.16 m(2) g(-1)). The higher MAE(365) values in nonmonsoon seasons are associated with fresh biomass burning emissions. This is further substantiated by a strong correlation (r = 0.79, P < 0.01) between Abs(365) (light absorption coefficient at 365 nm) and levoglucosan. We found, using fluorescence techniques, that humic-like and protein-like substances are the main chromophores in WS-BrC and responsible for 80.2 +/- 4.1% and 19.8 +/- 4.1% of the total fluorescence intensity, respectively. BrC contributes to 8.78 +/- 3.74% of total light absorption over the 300-700 nm wavelength range. Considering the dominant contribution of biomass burning to BrC over Godavari, this study suggests that reduction in biomass burning emission may be a practical method for climate change mitigation in South Asia.

关键词： Redox reactions Light absorption Biomass aerosols Quantum mechanics

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The aerosols, Radiation and Clouds in Southern Africa Field Campaign in Namibia: Overview, Illustrative Observations, and Way Forward

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BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY 2019年第7期100卷 1277-1298页

作者： Formenti, Paola D'Anna, Barbara Flamant, Cyrille Mallet, Marc Piketh, Stuart John Schepanski, Kerstin Waquet, Fabien Auriol, Frederique Brogniez, Gerard Burnet, Frederic Chaboureau, Jean-Pierre Chauvigne, Aurelien Chazette, Patrick Denjean, Cyrielle Desboeufs, Karine Doussin, Jean-Francois Elguindi, Nellie Feuerstein, Stefanie Gaetani, Marco Giorio, Chiara Klopper, Danitza Mallet, Marc Daniel Nabat, Pierre Monod, Anne Solmon, Fabien Namwoonde, Andreas Chikwililwa, Chibo Mushi, Roland Welton, Ellsworth Judd Holben, Brent Univ Paris Univ Paris Est Creteil Inst Pierre Simon Lapl LISAUMR CNRS 7583 Creteil France Univ Lyon 1 IRCE LYON UMR CNRS 5256 Villeurbanne France Aix Marseille Univ CNRS 7376 LCE Marseille France Univ Paris Saclay Sorbonne Univ Inst Pierre Simon Lapl LATMOSUMR CNRS 8190 Paris France Univ Toulouse Meteo France CNRS CNRM Toulouse France North West Univ Potchefstroom South Africa TROPOS Leipzig Germany Univ Lille UMR CNRS 8518 LOA Lille France Univ Toulouse CNRS UPS LA Toulouse France CEA CNRS UVSQ LSCE Gif Sur Yvette France Univ Paris Est Creteil LISA UMR CNRS 7583 Creteil France Univ Paris Diderot Inst Pierre Simon Lapl Creteil France Univ Padua Dipartimento Sci Chim Padua Italy Univ Paris Est Creteil LISA LISA UMR CNRS 7583 Creteil France Univ Paris Diderot Inst Pierre Simon Laplace Creteil France Univ Lyon 1 IRCELYON UMR CNRS 5256 Villeurbanne France Univ Namibia Sam Nujoma Marine & Coastal Resources Res Ctr Henties Bay Namibia Gobabeb Res & Training Ctr Henties Bay Namibia NASA Goddard Space Flight Ctr Greenbelt MD USA

The Aerosol, Radiation and Clouds in southern Africa (AEROCLO-sA) project investigates the role of aerosols on the regional climate of southern Africa. This is a unique environment where natural and anthropogenic aerosols and a semipermanent and widespread stratocumulus (Sc) cloud deck are found. The project aims to understand the dynamical, chemical, and radiative processes involved in aerosol-cloud-radiation interactions over land and ocean and under various meteorological conditions. The AEROCLO-sA field campaign was conducted in August and September of 2017 over Namibia. An aircraft equipped with active and passive remote sensors and aerosol in situ probes performed a total of 30 research flight hours. In parallel, a ground-based mobile station with state-of-the-art in situ aerosol probes and remote sensing instrumentation was implemented over coastal Namibia, and complemented by ground-based and balloonborne observations of the dynamical, thermodynamical, and physical properties of the lower troposphere. The focus laid on mineral dust emitted from salty pans and ephemeral riverbeds in northern Namibia, the advection of biomass-burning aerosol plumes from Angola subsequently transported over the Atlantic Ocean, and aerosols in the marine boundary layer at the ocean-atmosphere interface. This article presents an overview of the AEROCLO-sA field campaign with results from the airborne and surface measurements. These observations provide new knowledge of the interactions of aerosols and radiation in cloudy and clear skies in connection with the atmospheric dynamics over southern Africa. They will foster new advanced climate simulations and enhance the capability of spaceborne sensors, ultimately allowing a better prediction of future climate and weather in southern Africa.

关键词： aerosols

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Water diffusion measurements of single charged aerosols using H2O/D2O isotope exchange and Raman spectroscopy in an electrodynamic balance

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PHYSICAL CHEMISTRY CHEMICAL PHYSICS 2019年第27期21卷 15062-15071页

作者： Nadler, Katherine A. Kim, Pyeongeun Huang, Dao-Ling Xiong, Wei Continetti, Robert E. Univ Calif San Diego Dept Chem & Biochem 9500 Gilman Dr La Jolla CA 92093 USA

Sea spray aerosols contain a large array of organic compounds that contribute to high viscosities at low relative humidity and temperature thereby slowing translational diffusion of water. The Stokes-Einstein equation describes how viscosity is inversely correlated with the translational diffusion coefficient of the diffusing species. However, recent studies indicate that the Stokes-Einstein equation breaks down at high viscosities achieved in the particle phase (>10(12) Pa s), underestimating the predicted water diffusion coefficient by orders of magnitude and revealing the need for directly studying the diffusion of water in single aerosols. A new method is reported for measuring the water diffusion coefficient in single suspended charged sucrose-water and citric acid (CA)-water microdroplets in the 30-60 micron diameter range. The translational water diffusion coefficient is quantified using the H2O/D2O isotope exchange technique between 26 and 54% relative humidity (RH) for sucrose and 7 and 25% RH for CA using a recently developed mobile electrodynamic balance apparatus. The results are in good agreement with the literature, particularly the Vignes-type parameterization from experiments using isotope exchange and optical tweezers. Below 15% RH, CA droplets show incomplete H2O/D2O exchange. This mobile electrodynamic balance will allow future studies of atmospherically relevant chemical systems, including field studies.

关键词： Einstein equations diffusion ELECTRODYNAMIC BALANCE aerosols Viscosity calcium Relative Humidity Optical Tweezers aerosol MOISTURE DIFFUSION diffusion coefficient Raman spectrometry ISOTOPE EXCHANGE diameter range

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Concentrations and Adsorption Isotherms for Amphiphilic Surfactants in PM1 aerosols from Different Regions of Europe

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ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019年第21期53卷 12379-12388页

作者： Gerard, Violaine Noziere, Barbara Fine, Ludovic Ferronato, Corinne Singh, Dharmendra Kumar Frossard, Amanda A. Cohen, Ronald C. Asmi, Eija Lihavainen, Heikki Kivekas, Niku Aurela, Minna Brus, David Frka, Sanja Kusan, Ana Cvitesic Univ Lyon 1 CNRS Inst Rech Catalyse & Environm Lyon IRCELYON F-69626 Villeurbanne France Univ Calif Berkeley Dept Chem Berkeley CA 94720 USA Finnish Meteorol Inst Atmospher Composit Res FIN-00101 Helsinki Finland Svalbard Integrated Arctic Earth Observing Syst N-9171 Longyearbyen Norway Rudjer Boskovic Inst Div Marine & Environm Res Zagreb 10000 Croatia Inst Sci Mat Mulhouse IS2M CNRS F-68057 Mulhouse France Univ Georgia Dept Chem Athens GA 30602 USA

Predicting the activation of submicrometer particles into cloud droplets in the atmosphere remains a challenge. The importance of surface tension, sigma (mN m(-1)), in these processes has been evidenced by several works, but information on the "surfactants" lowering sigma in actual atmospheric particles remains scarce. In this work, PM1 aerosols from urban, coastal, and remote regions of Europe (Lyon, France, Rogoznica, Croatia, and Pallas, Finland, respectively) were investigated and found to contain amphiphilic surfactants in concentrations up to 2.8 mu g m(-3) in the air and 1.3 M in the particle dry volume. In Pallas, correlations with the PM1 chemical composition showed that amphiphilic surfactants were present in the entire range of particle sizes, supporting recent works. This implied that they were present in hundreds to thousands of particles cm(-3) and not only in a few large particles, as it has been hypothesized. Their adsorption isotherms and critical micelle concentration (CMC) were also determined. The low CMC obtained (3 x 10(-5)-9 x 10(-3) M) implies that surface tension depression should be significant for all the particles containing these compounds, even at activation (growth factor similar to 10). Amphiphilic surfactants are thus likely to enhance the CCN ability of submicrometer atmospheric particles.

关键词： Surface tension Atmospheric chemistry aerosols Particulate matter Surfactants

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