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Multi-spectral nephelometer characterization of urban aerosols

MEASUREMENT 2020年第0期154卷 107471-000页

作者： Devara, P. C. S. Vijayakumar, K. Safai, P. D. Univ Haryana ACOAST Gurgaon 122413 India Univ Haryana ASEES Gurgaon 122413 India SVU Dept Phys Tirupati 517502 Andhra Pradesh India IITM Pune 411008 Maharashtra India

Latest developments in science and technology enabled the research community to device numerous methods for real-time monitoring and analysis of aerosol properties. Different types of atmospheric aerosols, originating from both natural and anthropogenic sources, interfere with both incoming and out-going solar radiation and cause changes in weather and climate. The presence of these aerosols over any location is due to a combination of local sources and long-range transport which can result in a variety of mixing (both internal and external) states, mainly because of aging and interaction among diverse types of aerosols. These aerosols directly or indirectly interact with solar radiation and influence the lifetime and albedo of clouds and hence precipitation (Intergovernmental Panel on Climate Change (IPCC), 2007). Added, through their scattering and absorption properties, aerosol particles also affect visibility, air quality (Horvath, 1995), and human health (Brunekreef and Holgate, 2002, Balakrishnan et al., 2012, Nadadur et al., 2015). (C) 2020 Elsevier Ltd. All rights reserved.

关键词： aerosols Nephelometry Scattering coefficient Visibility Asymmetry parameter Radiative forcing

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Estimating the Columnar Concentrations of Black Carbon aerosols in China Using MODIS Products

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ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020年第18期54卷 11025-11036页

作者： Bao, Fangwen Li, Ying Cheng, Tianhai Gao, Jinhui Yuan, Shuyun Southern Univ Sci & Technol Ctr Ocean & Atmospher Sci SUSTech COAST Dept Ocean Sci & Engn Shenzhen 518055 Peoples R China Southern Univ Sci & Technol Shenzhen Key Lab Marine Archaea GeoOm Shenzhen 518055 Guangdong Peoples R China Chinese Acad Sci State Key Lab Remote Sensing Sci Inst Remote Sensing & Digital Earth Beijing 100094 Peoples R China

Black carbon (BC), the strongest light-absorbing particle, is believed to play substantial roles in regional air quality and global climate change. In this study, taking advantage of the high quality of moderate resolution imaging spectroradiometer products, we developed a new algorithm to estimate the BC columnar concentrations over China by simulating the BC and non-BC aerosol mixing states in detail. The results show that our new algorithm produces a reliable estimation of BC aerosols, in which BC columnar concentrations and their related parameters (aerosol absorption and BC surface concentration) show reasonable agreements and low biases compared with ground-based measurements. The uncertainties of BC retrievals are mainly associated with the surface and aerosol assumptions used in the algorithm, ranging from -14 to 44% at higher aerosol optical depth (AOD > 0.5). The proposed algorithm can improve the capability of space-borne aerosol remote sensing by successfully distinguishing BC from other aerosols. The acquired BC columnar concentrations enable the spatial pattern of serious BC aerosol pollution over East China to be characterized, showing that it exhibits higher levels in winter. These nationwide results are beneficial for estimating BC emissions, proposing mitigation strategies for air pollution, and potentially reducing the uncertainties of climate change studies.

关键词： Redox reactions Algorithms Absorption aerosols Optical properties

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Response of Hurricane Harvey's rainfall to anthropogenic aerosols: A sensitivity study based on spectral bin microphysics with simulated aerosols

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ATMOSPHERIC RESEARCH 2020年 242卷 104965-104965页

作者： Souri, Amir H. Choi, Yunsoo Kodros, John K. Jung, Jia Shpund, Jacob Pierce, Jeffrey R. Lynn, Barry H. Khain, Alexander Chance, Kelly Univ Houston Dept Earth & Atmospher Sci Houston TX USA Harvard Smithsonian Ctr Astrophys 60 Garden St Cambridge MA 02138 USA Colorado State Univ Dept Atmospher Sci Ft Collins CO 80523 USA Hebrew Univ Jerusalem Inst Earth Sci Jerusalem Israel

A number of human-induced elements contribute to influencing the intensity of tropical cyclones and prolonging their lifetime. Not only do ocean heat content, large-scale weather patterns, and surface properties affect the amount of release of energy, but the modulation from aerosol particles on cloud properties is also present. With Hurricane Harvey (2017) fairly isolated over Texas, there was a unique opportunity to study the indirect impact of aerosols on the amount of record-breaking rainfall over the greater Houston area. Due to the non-linear processes involved in clouds microstructure, aerosol properties and the variability associated with the atmospheric environment, the quantification of the response of storms to aerosols is complex. To this end, we first reproduce Harvey using the Weather Research and Forecasting (WRF) model coupled with a 3D-var assimilation framework that incorporates satellites, radio occultation, dropsondes, and surface measurements. We then study the aerosol indirect impacts using spectral bin microphysics in conjunction with aerosol properties simulated from the Goddard Earth Observing System (GEOS)-Chem Two-Moment Aerosol Sectional (TOMAS) model leveraging online aerosol microphysics with anthropogenic emissions (SP) and without ones (SC). In the vicinity of Harvey's landfall, the number concentration of cloud condensation nuclei at 1% supersaturation using the anthropogenic emissions is found to be one order of magnitude (855 cm(-3)) larger than those simulated with only natural emissions (83 cm(-3)). We observed that a narrow plume of anthropogenic aerosols from western Texas was transported over the area at the moment when deep convection initiated, accelerating updrafts through releasing more latent heat, which in turn, resulted in an average enhancement of precipitation by 25 mm (similar to 8%) over the greater Houston area. We observed a second peak at the right tail of the distribution of differences between experiments, whic

关键词： aerosols

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²¹⁰Pb and ⁷Be as Coupled Flux and Source Tracers for aerosols in the Pacific Ocean

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GLOBAL BIOGEOCHEMICAL CYCLES 2022年第8期36卷 e2022GB007378-e2022GB007378页

作者： Wei, Ziran Cochran, J. Kirk Horowitz, Evan Fitzgerald, Patrick Heilbrun, Christina Kadko, David Stephens, Mark Marsay, Chris M. Buck, Clifton S. Landing, William M. SUNY Stony Brook Sch Marine & Atmospher Sci Stony Brook NY 11794 USA Florida Int Univ Appl Res Ctr Miami FL 33199 USA Univ Georgia Skidaway Inst Oceanog Savannah GA USA Florida State Univ Dept Earth Ocean & Atmospher Sci Tallahassee FL 32306 USA

Deposition of aerosols to the surface ocean is an important factor affecting primary production in the surface ocean. However, the sources and fluxes of aerosols and associated trace elements remain poorly defined. Aerosol Pb-210, Po-210, and Be-7 data were collected on US GEOTRACES cruise GP15 (Pacific Meridional Transect, 152 degrees W;2018). Pb-210 fluxes are low close to the Alaskan margin, increase to a maximum at similar to 43 degrees N, then decrease to lower values. There is good agreement between Pb-210 fluxes and long-term land-based fluxes during the SEAREX program (1970-1980s), as well as between GP15 and GP16 (East Pacific Zonal Transect, 12 degrees S;2013) at adjacent stations. A normalized fraction f(Be-7, Pb-210) is used to discern aerosols with upper (high f) versus lower (low f) troposphere sources. Alaskan/North Pacific aerosols show significant continental influence while equatorial/South Pacific aerosols are supplied to the marine boundary layer from the upper troposphere. Lithogenic trace elements Al and Ti show inverse correlations with f(Be-7, Pb-210), supporting a continental boundary layer provenance while anthropogenic Pb shows no clear relationship with f(Be-7, Pb-210). All but four samples have Po-210/Pb-210 activity ratios <0.2 suggesting short aerosol residence time. Among the four samples (Po-210/Pb-210 = 0.42-0.88), two suggest an upper troposphere source and longer aerosol residence time while the remaining two cannot be explained by long aerosol residence time nor a significant component of dust. We hypothesize that enrichments of Po-210 in them are linked to Po enrichments in the sea surface microlayer, possibly through Po speciation as a dissolved organic or dimethyl polonide species.

关键词： fluxes aerosols Pacific Ocean

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A 265-Nanometer High-Power Deep-UV Light-Emitting Diode Rapidly Inactivates SARS-CoV-2 aerosols

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MSPHERE 2022年第2期7卷 e0094121页

作者： Ueki, Hiroshi Ito, Mutsumi Furusawa, Yuri Yamayoshi, Seiya Inoue, Shin-ichiro Kawaoka, Yoshihiro Univ Tokyo Inst Med Sci Dept Virol Tokyo Japan Natl Ctr Global Hlth & Med Ctr Global Viral Dis Tokyo Japan Kyoto Univ Inst Frontier Life & Med Sci Lab Ultrastructural Virol Kyoto Japan Natl Inst Informat & Commun Technol NICT Adv ICT Res Inst Kobe Hyogo Japan Univ Tokyo Inst Med Sci Int Res Ctr Infect Dis Dept Special Pathogens Tokyo Japan Univ Wisconsin Sch Vet Med Dept Pathobiol Sci Madison WI 53706 USA

We developed a 265-nm high-power DUV-LED irradiation system and quantitatively demonstrated that the DUV-LED can inactivate SARS-CoV-2 in suspensions and aerosols within very short irradiation times. We also found that the inactivation effect was about nine times greater against aerosolized SARS-CoV-2 than against SARS-CoV-2 suspensions. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (COVID-19) is an acute respiratory infection transmitted by droplets, aerosols, and contact. Controlling the spread of COVID-19 and developing effective decontamination options are urgent issues for the international community. Here, we report the quantitative inactivation of SARS-CoV-2 in liquid and aerosolized samples by a state-of-the-art, high-power, AlGaN-based, single-chip compact deep-UV (DUV) light-emitting diode (LED) that produces a record continuous-wave output power of 500 mW at its peak emission wavelength of 265 nm. Using this DUV-LED, we observed a greater-than-5-log reduction in infectious SARS-CoV-2 in liquid samples within very short irradiation times (<0.4 s). When we quantified the efficacy of the 265-nm DUV-LED in inactivating SARS-CoV-2, we found that DUV-LED inactivation of aerosolized SARS-CoV-2 was approximately nine times greater than that of SARS-CoV-2 suspension. Our data demonstrate that this newly developed, compact, high-power 265-nm DUV-LED irradiation system with remarkably high inactivation efficiency for aerosolized SARS-CoV-2 could be an effective and practical tool for controlling SARS-CoV-2 spread. IMPORTANCE We developed a 265-nm high-power DUV-LED irradiation system and quantitatively demonstrated that the DUV-LED can inactivate SARS-CoV-2 in suspensions and aerosols within very short irradiation times. We also found that the inactivation effect was about nine times greater against aerosolized SARS-CoV-2 than against SARS-CoV-2 suspensions. The DUV-LED has several advantages over conventional LEDs and mercury lamps, includi

关键词： COVID-19 LED SARS-CoV-2 aerosols deep UV

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To What Extent Biomass Burning aerosols Impact South America Seasonal Climate Predictions?

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GEOPHYSICAL RESEARCH LETTERS 2020年第16期47卷 e2020GL088096-e2020GL088096页

作者： Freire, Julliana L. M. Longo, Karla M. Freitas, Saulo R. Coelho, Caio A. S. Molod, Andrea M. Marshak, Jelena da Silva, Arlindo Ribeiro, Bruno Z. Natl Inst Space Res Ctr Weather Forecast & Climate Studies Cachoeira Paulista SP Brazil Univ Space Res Assoc Columbia MD USA NASA Goddard Space Flight Ctr Greenbelt MD USA SUNY Albany Dept Atmospher & Environm Sci Albany NY 12222 USA

We applied the Goddard Earth Observing System for subseasonal to seasonal climate prediction to assess the impact of inclusion biomass burning (BB) aerosols over South America (SA) during the austral winter. We also evaluated the model sensitivity to the BB emissions prescription using no emissions, monthly climatological, and daily emissions. Each hindcast consisted of four members running from June to November of each year between 2000 and 2015. Our results indicated that interactive BB aerosols improve the seasonal climate prediction performance over SA. More realistic daily based emissions significantly further improve the performance in comparison with the climatological ones. Therefore, improvements in the BB emissions representation are urged to represent the aerosol impacts on seasonal climate prediction performance adequately. Plain Language Summary Vegetation fires severely affect tropical forest and savannah-type biomes in South America (SA) during winter in Southern Hemisphere. Biomass burning (BB) aerosols are important agents changing energy budget and clouds. This study focused on assessing whether including aerosol-radiation-cloud interaction in a climate model, particularly the contribution of BB aerosols, can provide additional information for improving seasonal climate predictions. This study has two primary outcomes. First, that including BB aerosols does improve the model's ability to predicted precipitation and near-surface temperature in SA. Second, it proved it is indeed essential to improve BB emissions representation to further elevate seasonal climate prediction performance.

关键词： aerosols

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The formation and fate of aerosols in combustion systems for SCR NOx control strategies 114

The formation and fate of aerosols in combustion systems for...

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AWMA 114th Annual Conference and Exhibition

作者： Benson, Steven A. Schulte, Ryan S. Patwardhan, Shuchita Jones, Michael L. Microbeam Technologies Inc. 4200 James Ray Drive Ste 193 Grand ForksND United States MLJ Consulting Grand ForksND United States

Lignite coals of the Northern Great Plains in North America are relatively young coals that have unique physical and chemical properties. The specific properties of concern are those that impact the application of selective catalytic reduction (SCR). Coal-fired plants use SCR to convert NOx gases into N2. An SCR catalyst is susceptible to poisoning and masking/blinding by alkali and alkaline earth containing compounds, especially when present in sub-micrometer sized particles in the diameter range of 0.1 – 0.5 µm. SCR catalyst poisoning takes place when aerosols diffuse into pores and react with the active components of the catalyst. In high temperature coal-fired cyclone boilers, the vaporization of inorganic elements and partitioning between slag and fly ash have shown to produce high levels sodium and calcium sub-micrometer particles in the fly ash. Fly ash samples at the scrubber outlet show that submicron particles of sodium and potassium are still present. These particles have the potential to interact with and penetrate low dust or tail end SCR. The analysis of North Dakota lignite shows that firing lignite can lead to macroscopic and microscopic impacts on SCR catalyst performance. At the microscopic level, the ash from lignite fills the pores in the catalyst and can completely mask the pores within 4 months of operation. This shows that significant loading of the SCR by submicron particles leads to a dramatic drop in catalytic performance. Efforts to address the impacts of alkali on the performance of SCR catalysts include modified catalyst formulation as well as regeneration of poisoned catalysts. Modified catalysts have shown success in developing resistance to alkali poisoning while acid washing has shown success in regenerating catalysts poisoned by alkalis but not alkaline earth sulfates. Additional efforts include ongoing projects that have the capability of decreasing the alkali levels in the sub-micrometer particle loading. © 2021 Proceedings of the

关键词： aerosols

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Anthropogenic aerosols Modulated 20th-Century Sahel Rainfall Variability Via Their Impacts on North Atlantic Sea Surface Temperature

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GEOPHYSICAL RESEARCH LETTERS 2022年第1期49卷 e2021GL095629-e2021GL095629页

作者： Zhang, Shipeng Stier, Philip Dagan, Guy Wang, Minghuai Univ Oxford Dept Phys Atmospher Ocean & Planetary Phys Oxford England Hebrew Univ Jerusalem Inst Earth Sci Jerusalem Israel Nanjing Univ Joint Int Res Lab Atmospher & Earth Syst Sci Nanjing Peoples R China Nanjing Univ Sch Atmospher Sci Nanjing Peoples R China

The Sahel rainfall has a close teleconnection with North Atlantic sea surface temperature (NASST) variability, which has separately been shown to be affected by aerosols. Therefore, changes in regional aerosols emission could potentially drive multidecadal Sahel rainfall variability. Here we combine ensembles of state-of-the-art global climate models (the CESM and CanESM large ensemble simulations and CMIP6 models) with observational data sets to demonstrate that anthropogenic aerosols have significantly impacted 20th-century detrended Sahel rainfall multidecadal variability through modifying NASST. We show that aerosol-induced multidecadal variations of downward solar radiative fluxes over the North Atlantic cause NASST variability during the 20th century, altering the ITCZ position and dynamically linking aerosol effects to Sahel rainfall variability. This process chain is caused by aerosol-induced changes in radiative surface fluxes rather than changes in ocean circulations. CMIP6 models further suggest that aerosol-cloud interactions modulate the inter-model uncertainty of simulated NASST and potentially the Sahel rainfall variability.

关键词： aerosols Sahel rainfall North Atlantic variability aerosol-cloud-interactions

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Diurnal Evolution of Cloud Water Responses to aerosols

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JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 2022年第10期127卷 e2021JD035091-e2021JD035091页

作者： Rahu, J. Trofimov, H. Post, P. Toll, V. Univ Tartu Inst Phys Lab Atmospher Phys Tartu Estonia

Clouds play an essential role in the global energy budget, but the impact of anthropogenic aerosols on clouds is still poorly understood. We use 15-min temporal resolution geostationary satellite data to study the temporal evolution of polluted cloud tracks detected in the European part of Russia. Previous analysis of polluted cloud tracks shows that cloud water response to aerosols is bidirectional. Here, we show that cloud water gradually increases in the afternoon for polluted clouds in some cases. Aerosol-induced cloud thickening is much more likely in the case of thin unpolluted clouds. However, on average, there is less cloud water in the polluted clouds compared to the nearby unpolluted clouds. The temporal evolution of cloud thinning is not observed, and polluted clouds are thinner than the nearby unpolluted clouds since the early morning. The physical mechanisms leading to the observed changes and the influence of retrieval bias on the detected changes need further clarification. Our findings highlight the need to research the temporal evolution of cloud responses to aerosols to estimate the aerosol radiative forcing more accurately.

关键词： aerosol-cloud interactions clouds aerosols geostationary satellite cloud water response

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Effectiveness of barrier devices, high-volume evacuators, and extraoral suction devices on reducing dental aerosols for the dental operator A pilot study

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JOURNAL OF THE AMERICAN DENTAL ASSOCIATION 2022年第4期153卷 309-+页

作者： Remington, Wayne David Ott, Brian Chandler Hartka, Thomas Ryan Univ Virginia Dept Dent Charlottesville VA 22901 USA Univ Virginia Med Ctr Dept Emergency Med Charlottesville VA USA 2547 Frays Mill Rd Ruckersville VA 22968 USA

Background. The COVID-19 pandemic has increased the importance of minimizing exposure to aerosols generated during dental procedures. The authors' objective was to measure the aerosolized particles in the breathing zone of operators using several facial protection and filtration methods. Methods. Twenty-one dentists performed maxillary anterior incisor veneer preparations using a microscope and drape and loupes with or without a face shield. In each test condition, the following 3 levels of filtration were tested: no filtration, a high-volume evacuator [HVE], and an HVE with an extraoral suction device. Measurements were made using a mass monitor attached to the operator's chest with inlet within 10 inches of the operator's face. Results. The authors found that the microscope and drape provided the lowest levels of aerosolized particles compared with loupes with or without a face shield (P < .001). There was no detectable difference in the concentration of particles between operators wearing a face shield and wearing loupes alone (P = .47). The particles in each test condition were lowered when an HVE was used (P < .001) and further lowered with an extraoral suction device. Conclusions. The findings of this study suggest that the use of a surgical microscope and bag barrier drape, HVE, and extraoral suction device result in the lowest concentration of aerosolized particles. The face shield did not appear to offer any protection from aerosolized particles. HVE and extraoral suction were effective in decreasing aerosols regardless of the type of facial protection used. Practical Implications. Dentists can reduce exposure to aerosols with a drape, HVE, and extraoral suction.

关键词： aerosols microscope CDC OSHA dental handpieces filtration SARS

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