scholarly journals Ionic Surface Active Compounds in Atmospheric Aerosols

2002 ◽  
Vol 2 ◽  
pp. 1138-1146 ◽  
Author(s):  
Jariya Sukhapan ◽  
Peter Brimblecombe
Keyword(s):  
Surface Tension ◽  
Methylene Blue ◽  
Atmospheric Aerosols ◽  
Atmospheric Chemistry ◽  
Water Evaporation ◽  
Gas Transfer ◽  
Ambient Aerosols ◽  
Air Masses ◽  
Natural Surfactants ◽  
Surface Active Compounds

Surfactants in the atmosphere have several potential roles in atmospheric chemistry. They can form films on aqueous surfaces, which lowers the surface tension and possibly delays water evaporation and gaseous transportation across the aqueous interface. They can also increase the solubility of organic compounds in the aqueous phase. Recently, the decrease of surface tension in cloud growing droplets has been suggested as relevant to increases in the number of droplets of smaller size, potentially enhancing cloud albedo. Natural surfactants in the lung aid gas transfer and influence the dissolution rate of aerosol particles, so surfactants in atmospheric aerosols, once inhaled, may interact with pulmonary surfactants. Ambient aerosols were collected from the edge of Norwich, a small city in a largely agricultural region of England, and analysed for surfactants. Methylene blue, a conventional dye for detecting anionic surfactants, has been used as a colorimetric agent. The concentration of surfactants expressed as methylene blue active substances (MBAS) is in the range of 6–170 pmol m-3(air). A negative correlation with chloride aerosol indicates that these surfactants are probably not the well-known surfactants derived from marine spray. A more positive correlation with aerosol nitrate and gaseous NOxsupports an association with more polluted inland air masses. The surfactants found in aerosols seem to be relatively strong acids, compared with weaker acids such as the long-chain carboxylic acids previously proposed as atmospheric surfactants. Surfactants from the oxidation of organic materials (perhaps vegetation- or soil-derived) seem a likely source of these substances in the atmosphere.

Back to the Future: Reducing Atmospheric Particulate Matter Levels to Improve Human Health

2021 ◽  
Author(s):  
Spyros Pandis
Keyword(s):  
Particulate Matter ◽  
Atmospheric Aerosols ◽  
Atmospheric Chemistry ◽  
Control Strategy ◽  
Atmospheric Particulate Matter ◽  
Anthropogenic Emissions ◽  
The Us ◽  
Negative Impacts ◽  
Predictive Understanding ◽  
Physical And Chemical

<p>The human development of our planet has a variety of negative impacts on the composition of its atmosphere at every scale – locally, regionally, and even globally. One of these dramatic changes has been the increase in the mass concentrations of sub-micrometer particles by one to sometimes two orders of magnitude over populated areas in the Northern Hemisphere. These atmospheric aerosols can cause serious health problems, reduce visibility, contribute to acidic deposition and material damage, but are also cooling the planet by reflecting sunlight back to space. Atmospheric chemistry occurs within a fabric of complicated atmospheric dynamics and physics. This interplay often results in nonlinear and often counterintuitive changes of the system when anthropogenic emissions change. A major goal of our research has been to gain a predictive understanding of the physical and chemical processes that govern the dynamics, size, and chemical composition of atmospheric aerosols.</p><p>To illustrate the advances in the experimental techniques and theoretical tools in atmospheric aerosol science, we will go back to the beginning of the 21<sup>st</sup> century and we will revisit the design a particulate matter control strategy for the Eastern US based on the data, knowledge, and tools available at that time. We will then look at the effects of the parts of this control strategy that have been materialized and their effects on public health using the current understanding. Finally, we will look forward in ways of further improving air quality in the US and Europe.</p>

scholarly journals Stratosphere-troposphere exchange in the vicinity of a tropopause fold

2016 ◽  
Author(s):  
Christiane Hofmann ◽  
Astrid Kerkweg ◽  
Peter Hoor ◽  
Patrick Jöckel
Keyword(s):  
Atmospheric Chemistry ◽  
Climate Model ◽  
Ground Level ◽  
Global Model ◽  
Similar Process ◽  
Limited Area ◽  
Lagrangian Analysis ◽  
Air Masses ◽  
Model Instance ◽  
Lagrangian Study

Abstract. Transport of air masses from the stratosphere to the troposphere along tropopause folds can lead to peaked ozone concentrations at ground level and hereby influence the long-term trend of tropospheric ozone. To improve the understanding of responsible processes and preferred regions of exchange, transient and reversible exchange processes in the vicinity of a tropopause fold are analysed on the basis of a case study. The global and regional atmospheric chemistry model system MECO(n), which couples the limited-area atmospheric chemistry and climate model COSMO-CLM/MESSy to the global model ECHAM5/MESSy for Atmospheric Chemistry (EMAC) is applied. Using similar process parametrisations in both model instances, the system allows for very consistent, simultaneous simulations at different spatial resolutions. Simulated ozone enhancements at ground level, caused by descending stratospheric air masses, are evaluated with observational data. Because of the coarse resolution of the global model, the observed ozone enhancements are not captured by the global model instance. However, the results of the finer resolved, regional model instance coincide well with the measurements. Based on the combination of Eulerian and Lagrangian analysis methods it is shown that stratosphere-troposphere-exchange (STE) in the vicintity of the tropopause fold occurs in regions of turbulence and diabatic processes. Within the framework of a Lagrangian study the efficiency of mixing along a tropopause fold is quantified, showing that almost all (97 %) of the air masses originating in the tropopause fold are transported into the troposphere during the following two days.

scholarly journals A new approach for retrieving the UV–vis optical properties of ambient aerosols

2016 ◽  
Vol 9 (8) ◽  
pp. 3477-3490 ◽  
Author(s):  
Nir Bluvshtein ◽  
J. Michel Flores ◽  
Lior Segev ◽  
Yinon Rudich
Keyword(s):  
Optical Properties ◽  
Atmospheric Aerosols ◽  
Radiative Forcing ◽  
Complex Refractive Index ◽  
Single Scattering ◽  
Aerosol Size Distribution ◽  
Distribution Data ◽  
Ambient Aerosols ◽  
New Approach ◽  
Effective Radiative Forcing

Abstract. Atmospheric aerosols play an important part in the Earth's energy budget by scattering and absorbing incoming solar and outgoing terrestrial radiation. To quantify the effective radiative forcing due to aerosol–radiation interactions, researchers must obtain a detailed understanding of the spectrally dependent intensive and extensive optical properties of different aerosol types. Our new approach retrieves the optical coefficients and the single-scattering albedo of the total aerosol population over 300 to 650 nm wavelength, using extinction measurements from a broadband cavity-enhanced spectrometer at 315 to 345 nm and 390 to 420 nm, extinction and absorption measurements at 404 nm from a photoacoustic cell coupled to a cavity ring-down spectrometer, and scattering measurements from a three-wavelength integrating nephelometer. By combining these measurements with aerosol size distribution data, we retrieved the time- and wavelength-dependent effective complex refractive index of the aerosols. Retrieval simulations and laboratory measurements of brown carbon proxies showed low absolute errors and good agreement with expected and reported values. Finally, we implemented this new broadband method to achieve continuous spectral- and time-dependent monitoring of ambient aerosol population, including, for the first time, extinction measurements using cavity-enhanced spectrometry in the 315 to 345 nm UV range, in which significant light absorption may occur.

scholarly journals Average molecular weight of surfactants in aerosols

2007 ◽  
Vol 7 (5) ◽  
pp. 13805-13838 ◽  
Author(s):  
M. T. Latif ◽  
P. Brimblecombe
Keyword(s):  
Molecular Weight ◽  
Surface Tension ◽  
Atmospheric Aerosols ◽  
Average Molecular Weight ◽  
Molecular Size ◽  
Weight Fraction ◽  
Ozone Exposure ◽  
Before And After ◽  
Fine Mode ◽  
Active Substances

Abstract. Surfactants in atmospheric aerosols determined as methylene blue active substances (MBAS) and ethyl violet active substances (EVAS). The MBAS and EVAS concentrations can be correlated with surface tension as determined by pendant drop analysis. The effect of surface tension was more clearly indicated in fine mode aerosol extracts. The concentration of MBAS and EVAS was determined before and after ultrafiltration analysis using AMICON centrifuge tubes that define a 5000 Da (5 K Da) nominal molecular weight fraction. Overall, MBAS and to a greater extent EVAS predominates in fraction with molecular weight below 5 K Da. In case of aerosols collected in Malaysia the higher molecular fractions tended to be a more predominant. The MBAS and EVAS are correlated with yellow to brown colours in aerosol extracts. Further experiments showed possible sources of surfactants (e.g. petrol soot, diesel soot) in atmospheric aerosols to yield material having molecular size below 5 K Da except for humic acid. The concentration of surfactants from these sources increased after ozone exposure and for humic acids it also general included smaller molecular weight surfactants.

scholarly journals Ozone and carbon monoxide observations over open oceans on R/V <i>Mirai</i> from 67° S to 75° N during 2012 to 2017: Testing global chemical reanalysis in terms of Arctic processes, low ozone levels at low latitudes, and pollution transport

2019 ◽  
Author(s):  
Yugo Kanaya ◽  
Kazuyuki Miyazaki ◽  
Fumikazu Taketani ◽  
Takuma Miyakawa ◽  
Hisahiro Takashima ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Atmospheric Chemistry ◽  
Critical Evaluation ◽  
Chemical Transport ◽  
Tropospheric Chemistry ◽  
Set Covering ◽  
The Arctic ◽  
Pollution Transport ◽  
Data Set ◽  
Air Masses

Abstract. Constraints from ozone (O3) observations over oceans are needed in addition to those from terrestrial regions to fully understand global tropospheric chemistry and its impact on the climate. Here, we provide a large data set of ozone and carbon monoxide (CO) levels observed (for 11 666 and 10 681 h, respectively) over oceans. The data set is derived from observations made during 24 research cruise legs of R/V Mirai during 2012 to 2017, in the Southern, Indian, Pacific, and Arctic Oceans, covering the region from 67° S to 75° N. The data are suitable for critical evaluation of the over-ocean distribution of ozone derived from chemical transport models. We first give an overview of the statistics in the data set and highlight key features in terms of geographical distribution and air mass type. We then use the data set to evaluate ozone concentration fields from Tropospheric Chemistry Reanalysis version 2 (TCR-2), produced by assimilating a suite of satellite observations of multiple species into a chemical transport model, namely CHASER. For long-range transport of polluted air masses from continents to the oceans, during which the effects of forest fires and fossil fuel combustion were recognized, TCR-2 gave an excellent performance in reproducing the observed temporal variations and photochemical buildup of O3 when assessed from ΔO3 / ΔCO ratios. For clean marine conditions with low and stable CO concentrations, two focused analyses were performed. The first was in the Arctic (> 70° N) in September every year from 2013 to 2016; TCR-2 underpredicted O3 levels by 6.7 ppb (21 %) on average. The observed vertical profiles from O3 soundings from R/V Mirai during September 2014 had less steep vertical gradients at low altitudes (> 850 hPa) than those obtained TCR-2. This suggests the possibilities of more efficient descent of the O3-rich air from above or less efficient dry deposition on the surface than were assumed in the model. In the second analysis, over the western Pacific equatorial region (125–165° E, 10° S to 25° N), the observed O3 level frequently decreased to less than 10 ppb in comparison to that obtained with TCR-2, and also those obtained in most of the Atmospheric Chemistry Climate Model Intercomparison Project (ACCMIP) model runs for the decade from 2000. These results imply loss processes that are unaccounted for in the models. We found that the model’s positive bias positively correlated with the daytime residence times of air masses over a particular grid, namely 165–180° E and 15–30° N; an additional loss rate of 0.25 ppb h−1 in the grid best explained the gap. Halogen chemistry, which is commonly omitted from currently used models, might be active in this region and could have contributed to additional losses. Our open data set covering wide ocean regions is complementary to the Tropospheric Ozone Assessment Report data set, which basically comprises ground-based observations, and enables a fully global study of the behavior of O3.

scholarly journals Aerosol hygroscopicity at high (99 to 100%) relative humidities

2009 ◽  
Vol 9 (4) ◽  
pp. 15595-15640 ◽  
Author(s):  
C. R. Ruehl ◽  
P. Y. Chuang ◽  
A. Nenes
Keyword(s):  
Surface Tension ◽  
Inorganic Compounds ◽  
Droplet Diameter ◽  
Pure Water ◽  
Sodium Dodecyl ◽  
Bulk Solution ◽  
Active Compounds ◽  
Surface Active ◽  
Surface Active Compounds ◽  
Aerosol Hygroscopicity

Abstract. The hygroscopicity of an aerosol largely determines its influence on climate and, for smaller particles, atmospheric lifetime. While much aerosol hygroscopicity data is available at lower relative humidities (RH) and under cloud formation conditions (RH>100%), relatively little data is available at high RH (99.2 to 99.9%). We measured the size of droplets at high RH that had formed on particles composed of one of seven compounds with dry diameters between 0.1 and 0.5 μm, and calculated the hygroscopicity of these compounds. We use a parameterization of the Kelvin term, in addition to a standard parameterization (κ) of the Raoult term, to express the hygroscopicity of surface-active compounds. For inorganic compounds, hygroscopicity could reliably be predicted using water activity data and assuming a surface tension of pure water. In contrast, most organics exhibited a slight to mild increase in hygroscopicity with droplet diameter. This trend was strongest for sodium dodecyl sulfate (SDS), the most surface-active compound studied. The results suggest that partitioning of surface-active compounds away from the bulk solution, which reduces hygroscopicity, dominates any increases in hygroscopicity due to reduced surface tension. This is opposite to what is typically assumed for soluble surfactants. Furthermore, we saw no evidence that micellization limits SDS activity in micron-sized solution droplets, as observed in macroscopic solutions. These results suggest that while the high-RH hygroscopicity of inorganic compounds can be reliably predicted using readily available data, surface-activity parameters obtained from macroscopic solutions with organic solutes may be inappropriate for calculations of the hygroscopicity of micron-sized droplets.

A Future Multi-Platform Atmospheric Chemistry Measurement Campaign to Study Oxidation in Mixed Anthropogenic-Biogenic Air Masses

2021 ◽  
Author(s):  
Christopher Cantrell ◽  
Vincent Michoud ◽  
Paola Formenti ◽  
Jean-Francois Doussin ◽  
Stephanie Alhajj Moussa ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Los Angeles ◽  
Organic Compounds ◽  
Atmospheric Chemistry ◽  
Vapor Pressures ◽  
Air Masses ◽  
Measurement Campaign ◽  
Secondary Species ◽  
Volatile Organic ◽  
Urban Plumes

&lt;p&gt;It is well known that the high population density of urban regions leads to significant degradation of the quality of the air because of the emissions of pollutants that are by-products of energy production, transportation, and industry. The composition and chemistry of urban air has been studied for many decades and these studies have led to detailed understanding of the factors controlling, for example, the formation of ozone, peroxyacetyl nitrate and other secondary species. In the last 20 to 30 years, significant progress has been made in reducing emissions of volatile organic compounds (VOCs) and oxides of nitrogen (NO&lt;sub&gt;x&lt;/sub&gt;) in urban atmospheres. Substantial reductions in the abundance of secondary compounds, though, have been more elusive.&lt;/p&gt;&lt;p&gt;Research has continued to reveal more and more details of the complex processes involved in the atmospheric degradation of wide varieties of volatile organic compounds (VOCs) of anthropogenic and biospheric (BVOCs) origins. BVOCs include isoprene, monoterpenes and sesquiterpenes, and oxygenated VOCs (OVOCs, such as small alcohols). Emissions of BVOCs depend on several factors such as plant or tree species, temperature, and photosynthetically active radiation. They consist almost exclusively of unsaturated compounds with chemistry somewhat different from those of typical urban organic compound emissions. Oxidation of VOCs can lead to molecules of low volatility that are prone to uptake into the aerosol phase.&lt;/p&gt;&lt;p&gt;Recent studies conducted in megacities such as Paris, Mexico City, Los Angeles and those in China have led to significant advances in our understanding of the chemical evolution of urban plumes. However, important scientific questions remain on how mixing of anthropogenic and biogenic air masses modifies the composition of urban plumes and hence their impacts. Indeed, the proximity of cites to areas of strong biogenic emissions is not unusual. Many major cities at mid-latitudes are surrounded by forested areas.&lt;/p&gt;&lt;p&gt;ACROSS (Atmospheric ChemistRy Of the Suburban foreSt) is an integrative, innovative, multi-scale project awarded under the &amp;#8220;Make Our Planet Great Again&amp;#8221; (MOPGA) framework that seeks to definitively improve understanding of the impacts of mixing urban and biogenic air masses on the oxidation of atmospheric VOCs. The ACROSS working hypothesis is that this leads to changes in the production of oxygenated VOCs whose properties (e.g. vapor pressures) alter their importance in incorporation into SOA and their roles in production of ozone and other secondary species. Changes are also expected in the efficiency of radical recycling affecting the atmospheric oxidative capacity. Particularly important is NO&lt;sub&gt;x&lt;/sub&gt; transport to suburban biogenic environments and the resulting modification of key chemical processes.&lt;/p&gt;&lt;p&gt;A key highlight of ACROSS is an intensive, multi-platform measurement campaign in the summer of 2022. It will use instruments staged on an airborne platform, a tower in the Rambouillet Forest near Paris, and other ground sites. The data collected from this campaign will be analyzed and studied to extract information about tropospheric oxidation chemistry generally, but also changes observed in the situation of mixed urban and biogenic air masses.&lt;/p&gt;&lt;p&gt;This presentation will summarize plans for the ACROSS campaign.&lt;/p&gt;

scholarly journals Influence of Magnetic Field on Evaporation Rate and Surface Tension of Water

2018 ◽  
Vol 2 (4) ◽  
pp. 68 ◽  
Author(s):  
Emil Chibowski ◽  
Aleksandra Szcześ ◽  
Lucyna Hołysz
Keyword(s):  
Magnetic Field ◽  
Surface Tension ◽  
Hydrogen Bonds ◽  
Room Temperature ◽  
Evaporation Rate ◽  
Water Evaporation ◽  
Water Molecules ◽  
Surface Tension Data ◽  
Ring Magnet ◽  
The Magnetic Field

Using neodymium ring magnets (0.5–0.65 T), the experiments on the magnetic field (MF) effects on water evaporation rate and surface tension were performed at room temperature (22–24 °C). In accordance with the literature data, the enhanced evaporation rates were observed in the experiments conducted in a period of several days or weeks. However, the evaporated amounts of water (up to 440 mg over 150 min) in particular experiments differed. The evaporated amounts depended partially on which pole of the ring magnet was directed up. The relatively strong MF (0.65 T) caused a slight decrease in surface tension (−2.11 mN/m) which lasted longer than 60 min and the memory effect vanished slowly. The surface tension data reduced by the MF action are reported in the literature, although contrary results can be also found. The observed effects can be explained based on literature data of molecular simulations and the suggestion that MF affects the hydrogen bonds of intra- and inter-clusters of water molecules, possibly even causing breakage some of them. The Lorentz force influence is also considered. These mechanisms are discussed in the paper.

scholarly journals Triplet State Formation of Chromophoric Dissolved Organic Matter in Atmospheric Aerosols: Characteristics and Implications

2020 ◽  
Author(s):  
Qingcai Chen ◽  
Zhen Mu ◽  
Li Xu ◽  
Mamin Wang ◽  
Jin Wang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Triplet State ◽  
Atmospheric Aerosols ◽  
Formation Rate ◽  
Chromophoric Dissolved Organic Matter ◽  
Biomass Combustion ◽  
Triplet States ◽  
Ambient Aerosols ◽  
Paramagnetic Resonance

Abstract. There is chromophore dissolved organic matter (CDOM) in the atmosphere, which may form triplet-state chromophoric dissolved organic matter (3CDOM*) to further driving the formation of reactive oxygen species (ROS) under solar illumination. 3CDOM* contributes significantly to aerosol photochemistry and plays an important role in aerosol aging. We quantify the ability to form 3CDOM* and drive the formation of ROS by primary, secondary and ambient aerosols. Biomass combustion has the strongest 3CDOM* generation capacity and the weakest vehicle emission capacity. Ambient aerosol has a stronger ability to generate 3CDOM* in winter than in summer. Most of the triplet states generation conform to first-order reaction, but some of them do not due to the different quenching mechanism. The structural-activity relationship between the CDOM type and the 3CDOM* formation capacity shows that the two types of CDOM identified, which similar to the nitrogen-containing chromophores contributed 88 % to the formation of 3CDOM*. The estimated formation rate of 3CDOM* can reach ~ 100 μmol m−3 h−1 in the atmosphere in Xi'an, China, which is approximately one hundred thousand-times the hydroxyl radical (&amp;bullet;OH) production. This study verified that 3CDOM* drives at least 30 % of the singlet oxygen (1O2) and 31 % of the &amp;bullet;OH formed by aerosols using the spin trapping and electron paramagnetic resonance technique.

Fast-Atom Bombardment Mass Spectrometry in Heterogeneous Atmospheric Chemistry

2002 ◽  
Vol 8 (2) ◽  
pp. 131-138 ◽  
Author(s):  
G.B. Pronchev ◽  
I.A. Korobeinikova ◽  
A.N. Yermakov
Keyword(s):  
Mass Spectrometry ◽  
Atmospheric Aerosols ◽  
Atmospheric Chemistry ◽  
Fast Atom Bombardment ◽  
Atmospheric Water ◽  
Ferric Ions ◽  
Fab Mass Spectrometry ◽  
Essential Components ◽  
The Given ◽  
Heterogeneous Atmospheric Chemistry

The application of fast-atom bombardment (FAB) mass spectrometry to solving the problems of heterogeneous atmospheric chemistry is briefly reviewed. The method is useful in studying the state of surfaces and molecules adsorbed thereon and looks appropriate in investigations of the dynamics and mechanisms of chemical reactions occurring both on a surface and in a volume of moving particulate matter suspended in a gas. It was shown that composition of atmospheric aerosols and components dissolved in atmospheric water (clouds, fogs, mists etc.) can be determined by the FAB technique. The given method, as was found in our investigations, allows the discrimination of ferrous and ferric ions. Detection limits for concentrations of H2SO4 and Fe(II / III) ions as essential components of atmospheric water determined in model experiments are established at the level of 10−6 M.

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