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603 KiB

Open AccessArticle

Characterization of Fine Particulate Matter Emitted from the Resuspension of Road and Pavement Dust in the Metropolitan Area of São Paulo, Brazil

by Ivan Gregorio Hetem and Maria De Fatima Andrade

Atmosphere 2016, 7(3), 31; https://doi.org/10.3390/atmos7030031 - 23 Feb 2016

Cited by 40 | Viewed by 6522

Abstract

Many studies have been performed in order to characterize the sources of airborne particles in the Metropolitan Area of São Paulo (MASP), in Brazil. Those studies have been based on receptor modeling and most of the uncertainties in their results are related to [...] Read more.

Many studies have been performed in order to characterize the sources of airborne particles in the Metropolitan Area of São Paulo (MASP), in Brazil. Those studies have been based on receptor modeling and most of the uncertainties in their results are related to the emission profile of the resuspended road dust particles. In this study, we analyzed the composition of resuspended road dust particles in different environments: local streets, paved roads inside traffic tunnels, and high traffic streets. We analyzed the samples to quantify the concentrations of trace elements and black carbon. On the basis of that analysis, we developed emission profiles of the resuspended road dust that are representative of the different types of urban pavement in the MASP. This study is important given the international efforts in improving emissions factors with local characteristics, mainly in South America and other regions for which there is a lack of related information. This work presents emission profiles derived from resuspended road dust samples that are representative of the different types of urban pavement in the Metropolitan Area of São Paulo. Full article

(This article belongs to the Special Issue Atmospheric Composition Observations)

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4739 KiB

Open AccessArticle

Decreasing Aerosol Loading in the North American Monsoon Region

by Aishwarya Raman, Avelino F. Arellano and Armin Sorooshian

Atmosphere 2016, 7(2), 24; https://doi.org/10.3390/atmos7020024 - 5 Feb 2016

Cited by 10 | Viewed by 5594

Abstract

We examine the spatio-temporal variability of aerosol loading in the recent decade (2005–2014) over the North American Monsoon (NAM) region. Emerging patterns are characterized using aerosol optical depth (AOD) retrievals from the NASA Terra/Moderate Resolution Imaging Spectroradiometer (MODIS) instrument along with a suite [...] Read more.

We examine the spatio-temporal variability of aerosol loading in the recent decade (2005–2014) over the North American Monsoon (NAM) region. Emerging patterns are characterized using aerosol optical depth (AOD) retrievals from the NASA Terra/Moderate Resolution Imaging Spectroradiometer (MODIS) instrument along with a suite of satellite retrievals of atmospheric and land-surface properties. We selected 20 aerosol hotspots and classified them into fire, anthropogenic, dust, and NAM alley clusters based on the dominant driver influencing aerosol variability. We then analyzed multivariate statistics of associated anomalies during pre-, monsoon, and post-monsoon periods. Our results show a decrease in aerosol loading for the entire NAM region, confirming previous reports of a declining AOD trend over the continental United States. This is evident during pre-monsoon and monsoon for fire and anthropogenic clusters, which are associated with a decrease in the lower and upper quartile of fire counts and carbon monoxide, respectively. The overall pattern is obfuscated in the NAM alley, especially during monsoon and post-monsoon seasons. While the NAM alley is mostly affected by monsoon precipitation, the frequent occurrence of dust storms in the area modulates this trend. We find that aerosol loading in the dust cluster is associated with observed vegetation index and has only slightly decreased in the recent decade. Full article

(This article belongs to the Special Issue Atmospheric Composition Observations)

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6441 KiB

Open AccessArticle

Windblown Dust Deposition Forecasting and Spread of Contamination around Mine Tailings

by Michael Stovern, Héctor Guzmán, Kyle P. Rine, Omar Felix, Matthew King, Wendell P. Ela, Eric A. Betterton and Avelino Eduardo Sáez

Atmosphere 2016, 7(2), 16; https://doi.org/10.3390/atmos7020016 - 28 Jan 2016

Cited by 29 | Viewed by 6898

Abstract

Wind erosion, transport and deposition of windblown dust from anthropogenic sources, such as mine tailings impoundments, can have significant effects on the surrounding environment. The lack of vegetation and the vertical protrusion of the mine tailings above the neighboring terrain make the tailings [...] Read more.

Wind erosion, transport and deposition of windblown dust from anthropogenic sources, such as mine tailings impoundments, can have significant effects on the surrounding environment. The lack of vegetation and the vertical protrusion of the mine tailings above the neighboring terrain make the tailings susceptible to wind erosion. Modeling the erosion, transport and deposition of particulate matter from mine tailings is a challenge for many reasons, including heterogeneity of the soil surface, vegetative canopy coverage, dynamic meteorological conditions and topographic influences. In this work, a previously developed Deposition Forecasting Model (DFM) that is specifically designed to model the transport of particulate matter from mine tailings impoundments is verified using dust collection and topsoil measurements. The DFM is initialized using data from an operational Weather Research and Forecasting (WRF) model. The forecast deposition patterns are compared to dust collected by inverted-disc samplers and determined through gravimetric, chemical composition and lead isotopic analysis. The DFM is capable of predicting dust deposition patterns from the tailings impoundment to the surrounding area. The methodology and approach employed in this work can be generalized to other contaminated sites from which dust transport to the local environment can be assessed as a potential route for human exposure. Full article

(This article belongs to the Special Issue Atmospheric Composition Observations)

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1340 KiB

Open AccessArticle

Frequency and Character of Extreme Aerosol Events in the Southwestern United States: A Case Study Analysis in Arizona

by David H. Lopez, Michael R. Rabbani, Ewan Crosbie, Aishwarya Raman, Avelino F. Arellano and Armin Sorooshian

Atmosphere 2016, 7(1), 1; https://doi.org/10.3390/atmos7010001 - 23 Dec 2015

Cited by 26 | Viewed by 6197

Abstract

This study uses more than a decade’s worth of data across Arizona to characterize the spatiotemporal distribution, frequency, and source of extreme aerosol events, defined as when the concentration of a species on a particular day exceeds that of the average plus two [...] Read more.

This study uses more than a decade’s worth of data across Arizona to characterize the spatiotemporal distribution, frequency, and source of extreme aerosol events, defined as when the concentration of a species on a particular day exceeds that of the average plus two standard deviations for that given month. Depending on which of eight sites studied, between 5% and 7% of the total days exhibited an extreme aerosol event due to either extreme levels of PM₁₀, PM_2.5, and/or fine soil. Grand Canyon exhibited the most extreme event days (120, i.e., 7% of its total days). Fine soil is the pollutant type that most frequently impacted multiple sites at once at an extreme level. PM_10, PM_2.5, fine soil, non-Asian dust, and Elemental Carbon extreme events occurred most frequently in August. Nearly all Asian dust extreme events occurred between March and June. Extreme Elemental Carbon events have decreased as a function of time with statistical significance, while other pollutant categories did not show any significant change. Extreme events were most frequent for the various pollutant categories on either Wednesday or Thursday, but there was no statistically significant difference in the number of events on any particular day or on weekends versus weekdays. Full article

(This article belongs to the Special Issue Atmospheric Composition Observations)

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4610 KiB

Open AccessArticle

Effect of Nearby Forest Fires on Ground Level Ozone Concentrations in Santiago, Chile

by María A. Rubio, Eduardo Lissi, Ernesto Gramsch and René D. Garreaud

Atmosphere 2015, 6(12), 1926-1938; https://doi.org/10.3390/atmos6121838 - 17 Dec 2015

Cited by 18 | Viewed by 7469

Abstract

On 4 and 8 January 2014, at the height of the austral summer, intense wildfires in forests and dry pastures occurred in the Melipilla sector, located about 70 km to the southwest of Santiago, the Chilean capital, affecting more than 6 million inhabitants. [...] Read more.

On 4 and 8 January 2014, at the height of the austral summer, intense wildfires in forests and dry pastures occurred in the Melipilla sector, located about 70 km to the southwest of Santiago, the Chilean capital, affecting more than 6 million inhabitants. Low level winds transported the forest fire plume towards Santiago causing a striking decrease in visibility and a marked increase in the concentration of both primary (PM₁₀ and CO) and secondary (Ozone) pollutants in the urban atmosphere. In particular, ozone maximum concentrations in the Santiago basin reached hourly averages well above 80 ppb, the national air quality standard. This ozone increase took place at the three sampling sites considered in the present study. These large values can be explained in terms of high NOx concentrations and NO₂/NO ratios in biomass burning emissions. Full article

(This article belongs to the Special Issue Atmospheric Composition Observations)

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6536 KiB

Open AccessArticle

The Influence of Sandstorms and Long-Range Transport on Polycyclic Aromatic Hydrocarbons (PAHs) in PM_2.5 in the High-Altitude Atmosphere of Southern China

by Minmin Yang, Yan Wang, Qiang Liu, Aijun Ding and Yuhua Li

Atmosphere 2015, 6(11), 1633-1651; https://doi.org/10.3390/atmos6111633 - 30 Oct 2015

Cited by 16 | Viewed by 6732

Abstract

PM_2.5 (Particulate Matter 2.5) samples were collected at Mount Heng and analyzed for polycyclic aromatic hydrocarbons (PAHs). During sampling, a sandstorm from northern China struck Mount Heng and resulted in a mean PM_2.5 concentration of 150.61 μg/m³, which greatly [...] Read more.

PM_2.5 (Particulate Matter 2.5) samples were collected at Mount Heng and analyzed for polycyclic aromatic hydrocarbons (PAHs). During sampling, a sandstorm from northern China struck Mount Heng and resulted in a mean PM_2.5 concentration of 150.61 μg/m³, which greatly exceeded the concentration measured under normal conditions (no sandstorm: 58.50 μg/m³). The average mass of PAHs in PM_2.5 was 30.70 μg/g, which was much lower than in the non-sandstorm samples (80.80 μg/g). Therefore, the sandstorm increased particle levels but decreased PAH concentrations due to dilution and turbulence. During the sandstorm, the concentrations of 4- and 5-ring PAHs were below their detection limits, and 6-ring PAHs were the most abundant. Under normal conditions, the concentrations of 2-, 3- and 6-ring PAHs were higher, and 4- and 5-ring PAHs were lower relative to the other sampling sites. In general, the PAH contamination was low to medium at Mount Heng. Higher LMW (low molecular weight) concentrations were primarily linked to meteorological conditions, and higher HMW (high molecular weight) concentrations primarily resulted from long-range transport. Analysis of diagnostic ratios indicated that PM_2.5 PAHs had been emitted during the combustion of coal, wood or petroleum. The transport characteristics and origins of the PAHs were investigated using backwards Lagrangian particle dispersion modeling. Under normal conditions, the “footprint” retroplumes and potential source contributions of PAHs for the highest and lowest concentrations indicated that local sources had little effect. In contrast, long-range transport played a vital role in the levels of PM_2.5 and PAHs in the high-altitude atmosphere. Full article

(This article belongs to the Special Issue Atmospheric Composition Observations)

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1028 KiB

Open AccessArticle

CCN Properties of Organic Aerosol Collected Below and within Marine Stratocumulus Clouds near Monterey, California

by Akua Asa-Awuku, Armin Sorooshian, Richard C. Flagan, John H. Seinfeld and Athanasios Nenes

Atmosphere 2015, 6(11), 1590-1607; https://doi.org/10.3390/atmos6111590 - 28 Oct 2015

Cited by 8 | Viewed by 5899

Abstract

The composition of aerosol from cloud droplets differs from that below cloud. Its implications for the Cloud Condensation Nuclei (CCN) activity are the focus of this study. Water-soluble organic matter from below cloud, and cloud droplet residuals off the coast of Monterey, California [...] Read more.

The composition of aerosol from cloud droplets differs from that below cloud. Its implications for the Cloud Condensation Nuclei (CCN) activity are the focus of this study. Water-soluble organic matter from below cloud, and cloud droplet residuals off the coast of Monterey, California were collected; offline chemical composition, CCN activity and surface tension measurements coupled with Köhler Theory Analysis are used to infer the molar volume and surfactant characteristics of organics in both samples. Based on the surface tension depression of the samples, it is unlikely that the aerosol contains strong surfactants. The activation kinetics for all samples examined are consistent with rapid (NH₄)₂SO₄ calibration aerosol. This is consistent with our current understanding of droplet kinetics for ambient CCN. However, the carbonaceous material in cloud drop residuals is far more hygroscopic than in sub-cloud aerosol, suggestive of the impact of cloud chemistry on the hygroscopic properties of organic matter. Full article

(This article belongs to the Special Issue Atmospheric Composition Observations)

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533 KiB

Open AccessArticle

Inland Concentrations of Cl₂ and ClNO₂ in Southeast Texas Suggest Chlorine Chemistry Significantly Contributes to Atmospheric Reactivity

by Cameron B. Faxon, Jeffrey K. Bean and Lea Hildebrandt Ruiz

Atmosphere 2015, 6(10), 1487-1506; https://doi.org/10.3390/atmos6101487 - 14 Oct 2015

Cited by 58 | Viewed by 9200

Abstract

Measurements of molecular chlorine (Cl₂), nitryl chloride (ClNO₂), and dinitrogen pentoxide (N₂O₅) were taken as part of the DISCOVER-AQ Texas 2013 campaign with a High Resolution Time-of-Flight Chemical Ionization Mass Spectrometer (HR-ToF-CIMS) using iodide (I-) [...] Read more.

Measurements of molecular chlorine (Cl₂), nitryl chloride (ClNO₂), and dinitrogen pentoxide (N₂O₅) were taken as part of the DISCOVER-AQ Texas 2013 campaign with a High Resolution Time-of-Flight Chemical Ionization Mass Spectrometer (HR-ToF-CIMS) using iodide (I-) as a reagent ion. ClNO₂ concentrations exceeding 50 ppt were regularly detected with peak concentrations typically occurring between 7:00 a.m. and 10:00 am. Hourly averaged Cl₂ concentrations peaked daily between 3:00 p.m. and 4:00 p.m., with a 29-day average of 0.9 ± 0.3 (1σ) ppt. A day-time Cl₂ source of up to 35 ppt∙h⁻¹ is required to explain these observations, corresponding to a maximum chlorine radical (Cl^•) production rate of 70 ppt∙h⁻¹. Modeling of the Cl₂ source suggests that it can enhance daily maximum O₃ and RO₂^•concentrations by 8%–10% and 28%–50%, respectively. Modeling of observed ClNO₂ assuming a well-mixed nocturnal boundary layer indicates O₃ and RO₂^• enhancements of up to 2.1% and 38%, respectively, with a maximum impact in the early morning. These enhancements affect the formation of secondary organic aerosol and compliance with air quality standards for ozone and particulate matter. Full article

(This article belongs to the Special Issue Atmospheric Composition Observations)

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551 KiB

Open AccessArticle

Analysis of PAHs Associated with Particulate Matter PM_2.5 in Two Places at the City of Cuernavaca, Morelos, México

by Hugo Saldarriaga-Noreña, Rebecca López-Márquez, Mario Murillo-Tovar, Leonel Hernández-Mena, Efrén Ospina-Noreña, Enrique Sánchez-Salinas, Stefan Waliszewski and Silvia Montiel-Palma

Atmosphere 2015, 6(9), 1259-1270; https://doi.org/10.3390/atmos6091259 - 25 Aug 2015

Cited by 16 | Viewed by 5269

Abstract

This study was carried out between January and February 2013, at two sites in the city of Cuernavaca, México, using low-volume equipment. Fifteen Polycyclic aromatic hydrocarbons (PAHs), were identified by gas chromatography coupled with mass spectrometry. The total average concentration observed for PAHs [...] Read more.

This study was carried out between January and February 2013, at two sites in the city of Cuernavaca, México, using low-volume equipment. Fifteen Polycyclic aromatic hydrocarbons (PAHs), were identified by gas chromatography coupled with mass spectrometry. The total average concentration observed for PAHs was 24.0 ng·m⁻³, with the high molecular weight compounds being the most abundant. The estimated equivalent concentration for Benzo (a) P (BaPE) was 4.05 ng·m⁻³. Diagnostic ratios together with the principal components analysis (PCA) allowed for establishing coal burning and vehicle emissions as being the main sources of these compounds in the area. The PAHs used to calculate this index account for 51% of the 15 PAHs identified, which probably involves a risk to the exposed population. Full article

(This article belongs to the Special Issue Atmospheric Composition Observations)

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5310 KiB

Open AccessArticle

Characteristics of PM₁₀ and PM_2.5 at Mount Wutai Buddhism Scenic Spot, Shanxi, China

by Zhihui Wu, Fenwu Liu and Wenhua Fan

Atmosphere 2015, 6(8), 1195-1210; https://doi.org/10.3390/atmos6081195 - 18 Aug 2015

Cited by 16 | Viewed by 9211

Abstract

A survey was conducted to effectively investigate the characteristics of airborne particulate pollutants PM₁₀ and PM_2.5during the peak tourist season at Mount Wutai Buddhism scenic spot, Shanxi, China. Characteristics of the PM₁₀ and PM_2.5 in Wu Ye Temple [...] Read more.

A survey was conducted to effectively investigate the characteristics of airborne particulate pollutants PM₁₀ and PM_2.5during the peak tourist season at Mount Wutai Buddhism scenic spot, Shanxi, China. Characteristics of the PM₁₀ and PM_2.5 in Wu Ye Temple (core incense burners), Manjusri Temple (a traffic hub), Yang Bai Lin Village (a residential district), and Nan Shan Temple (located in a primitive forest district), were determined. The results showed that the PM₁₀ concentration was more than 1.01–1.14 times higher than the threshold (50 μg/m³) of World Health Organization Air Quality Guidelines (2005), and the PM_2.5 concentration was 1.75–2.70 times higher than the above standard (25 μg/m³). Particle size analysis indicated that the distribution of fine particulate matter in Wu Ye Temple ranged from 0 to 3.30 μm. In other sampling points, the fine particulate was mainly distributed in the range of 0–5.90 μm. The particulates in Wu Ye Temple were mainly characterized by spherical, rod-like, and irregular soot aggregates (PM₁₀) and spherical particles of dust (PM_2.5). Manjusri Temple and Yang Bai Lin Village predominantly exhibited irregular soil mineral particulate matter (PM₁₀), and amorphous ultrafine soot particulate matter (PM_2.5). Full article

(This article belongs to the Special Issue Atmospheric Composition Observations)

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3195 KiB

Open AccessArticle

Study of Black Sand Particles from Sand Dunes in Badr, Saudi Arabia Using Electron Microscopy

by Haider Abbas Khwaja, Omar Siraj Aburizaiza, Daniel L. Hershey, Azhar Siddique, David A. Guerrieri P. E., Jahan Zeb, Mohammad Abbass, Donald R. Blake, Mirza Mozammel Hussain, Abdullah Jameel Aburiziza, Malissa A. Kramer and Isobel J. Simpson

Atmosphere 2015, 6(8), 1175-1194; https://doi.org/10.3390/atmos6081175 - 17 Aug 2015

Cited by 4 | Viewed by 11647

Abstract

Particulate air pollution is a health concern. This study determines the microscopic make-up of different varieties of sand particles collected at a sand dune site in Badr, Saudi Arabia in 2012. Three categories of sand were studied: black sand, white sand, and volcanic [...] Read more.

Particulate air pollution is a health concern. This study determines the microscopic make-up of different varieties of sand particles collected at a sand dune site in Badr, Saudi Arabia in 2012. Three categories of sand were studied: black sand, white sand, and volcanic sand. The study used multiple high resolution electron microscopies to study the morphologies, emission source types, size, and elemental composition of the particles, and to evaluate the presence of surface “coatings or contaminants” deposited or transported by the black sand particles. White sand was comprised of natural coarse particles linked to wind-blown releases from crustal surfaces, weathering of igneous/metamorphic rock sources, and volcanic activities. Black sand particles exhibited different morphologies and microstructures (surface roughness) compared with the white sand and volcanic sand. Morphological Scanning Electron Microscopy (SEM) and Laser Scanning Microscopy (LSM) analyses revealed that the black sand contained fine and ultrafine particles (50 to 500 nm ranges) and was strongly magnetic, indicating the mineral magnetite or elemental iron. Aqueous extracts of black sands were acidic (pH = 5.0). Fe, C, O, Ti, Si, V, and S dominated the composition of black sand. Results suggest that carbon and other contaminant fine particles were produced by fossil-fuel combustion and industrial emissions in heavily industrialized areas of Haifa and Yanbu, and transported as cloud condensation nuclei to Douf Mountain. The suite of techniques used in this study has yielded an in-depth characterization of sand particles. Such information will be needed in future environmental, toxicological, epidemiological, and source apportionment studies. Full article

(This article belongs to the Special Issue Atmospheric Composition Observations)

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713 KiB

Open AccessArticle

The Impact of Selected Parameters on Visibility: First Results from a Long-Term Campaign in Warsaw, Poland

by Grzegorz Majewski, Wioletta Rogula-Kozłowska, Piotr O. Czechowski, Artur Badyda and Andrzej Brandyk

Atmosphere 2015, 6(8), 1154-1174; https://doi.org/10.3390/atmos6081154 - 12 Aug 2015

Cited by 35 | Viewed by 8073

Abstract

The aim of this study was to investigate how atmospheric air pollutants and meteorological conditions affected atmospheric visibility in the largest Polish agglomeration. The correlation analysis, principal component analysis (PCA) and generalized regression models (GRMs) were used to accomplish this objective. The meteorological [...] Read more.

The aim of this study was to investigate how atmospheric air pollutants and meteorological conditions affected atmospheric visibility in the largest Polish agglomeration. The correlation analysis, principal component analysis (PCA) and generalized regression models (GRMs) were used to accomplish this objective. The meteorological parameters (temperature, relative humidity, precipitation, wind speed and insolation) and concentrations of the air pollutants (PM₁₀, SO₂, NO₂, CO and O₃) were recorded in 2004–2013. The data came from the Ursynów-SGGW, MzWarszUrsynów and Okęcie monitoring stations, located in the south of Warsaw (Poland). It was shown that the PM₁₀ concentration was the most important parameter affecting the visibility in Warsaw. The concentration, and indirectly the visibility, was mainly affected by the pollutant emission from the flat/building heating (combustion of various fuels). It changed intensively during the research period. There were also periods in which this emission type did not have a great influence on the pollutant concentrations (mainly PM₁₀) and visibility. In such seasons, the research revealed the influence of the traffic emission and secondary aerosol formation processes on the visibility. Full article

(This article belongs to the Special Issue Atmospheric Composition Observations)

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2362 KiB

Open AccessArticle

Airborne Aerosol in Situ Measurements during TCAP: A Closure Study of Total Scattering

by Evgueni Kassianov, Larry K. Berg, Mikhail Pekour, James Barnard, Duli Chand, Connor Flynn, Mikhail Ovchinnikov, Arthur Sedlacek, Beat Schmid, John Shilling, Jason Tomlinson and Jerome Fast

Atmosphere 2015, 6(8), 1069-1101; https://doi.org/10.3390/atmos6081069 - 31 Jul 2015

Cited by 15 | Viewed by 8037

Abstract

We present a framework for calculating the total scattering of both non-absorbing and absorbing aerosol at ambient conditions from aircraft data. Our framework is developed emphasizing the explicit use of chemical composition data for estimating the complex refractive index (RI) of particles, and [...] Read more.

We present a framework for calculating the total scattering of both non-absorbing and absorbing aerosol at ambient conditions from aircraft data. Our framework is developed emphasizing the explicit use of chemical composition data for estimating the complex refractive index (RI) of particles, and thus obtaining improved ambient size spectra derived from Optical Particle Counter (OPC) measurements. The feasibility of our framework for improved calculations of total scattering is demonstrated using three types of data collected by the U.S. Department of Energy’s (DOE) aircraft during the Two-Column Aerosol Project (TCAP). Namely, these data types are: (1) size distributions measured by a suite of OPC’s; (2) chemical composition data measured by an Aerosol Mass Spectrometer and a Single Particle Soot Photometer; and (3) the dry total scattering coefficient measured by a integrating nephelometer and scattering enhancement factor measured with a humidification system. We demonstrate that good agreement (~10%) between the observed and calculated scattering can be obtained under ambient conditions (RH < 80%) by applying chemical composition data for the RI-based correction of the OPC-derived size spectra. We also demonstrate that ignoring the RI-based correction or using non-representative RI values can cause a substantial underestimation (~40%) or overestimation (~35%) of the calculated scattering, respectively. Full article

(This article belongs to the Special Issue Atmospheric Composition Observations)

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847 KiB

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Chemical Composition of Water Soluble Inorganic Species in Precipitation at Shihwa Basin, Korea

by Seung-Myung Park, Beom-Keun Seo, Gangwoong Lee, Sung-Hyun Kahng and Yu Woon Jang

Atmosphere 2015, 6(6), 732-750; https://doi.org/10.3390/atmos6060732 - 25 May 2015

Cited by 38 | Viewed by 6729

Abstract

Weekly rain samples were collected in coastal areas of the Shihwa Basin (Korea) from June 2000 to November 2007. The study region includes industrial, rural, and agricultural areas. Wet precipitation was analyzed for conductivity, pH, Cl⁻, NO₃⁻, SO [...] Read more.

Weekly rain samples were collected in coastal areas of the Shihwa Basin (Korea) from June 2000 to November 2007. The study region includes industrial, rural, and agricultural areas. Wet precipitation was analyzed for conductivity, pH, Cl⁻, NO₃⁻, SO₄²⁻, Na⁺, K⁺, Mg²⁺, NH₄⁺, and Ca²⁺. The major components of precipitation in the Shihwa Basin were NH₄⁺, volume-weighted mean (VWM) of 44.6 µeq∙L⁻¹, representing 43% of all cations, and SO₄²⁻, with the highest concentration among the anions (55%) at all stations. The pH ranged from 3.4 to 7.7 with a VMM of 4.84. H⁺ was weakly but positively correlated with SO₄²⁻ (r = 0.39, p < 0.001) and NO₃⁻ (r = 0.38, p < 0.001). About 66% of the acidity was neutralized by NH₄⁺ and Ca²⁺. The Cl⁻/Na⁺ ratio of the precipitation was 37% higher than seawater Cl⁻/Na⁺. The high SO₄²⁻/NO₃⁻ ratio of 2.3 is attributed to the influence of the surrounding industrial sources. Results from positive matrix factorization showed that the precipitation chemistry in Shihwa Basin was influenced by secondary nitrate and sulfate (41% ± 1.1%), followed by sea salt and Asian dust, contributing 23% ± 3.9% and 17% ± 0.2%, respectively. In this study, the annual trends of SO₄²⁻ and NO₃⁻ (p < 0.05) increased, different from the trends in some locations, due to the influence of the expanding power generating facilities located in the upwind area. The increasing trends of SO₄²⁻ and NO₃⁻ in the study region have important implications for reducing air pollution in accordance with national energy policy. Full article

(This article belongs to the Special Issue Atmospheric Composition Observations)

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1247 KiB

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The Possible Role of Penning Ionization Processes in Planetary Atmospheres

by Stefano Falcinelli, Fernando Pirani and Franco Vecchiocattivi

Atmosphere 2015, 6(3), 299-317; https://doi.org/10.3390/atmos6030299 - 11 Mar 2015

Cited by 54 | Viewed by 7611

Abstract

In this paper we suggest Penning ionization as an important route of formation for ionic species in upper planetary atmospheres. Our goal is to provide relevant tools to researchers working on kinetic models of atmospheric interest, in order to include Penning ionizations in [...] Read more.

In this paper we suggest Penning ionization as an important route of formation for ionic species in upper planetary atmospheres. Our goal is to provide relevant tools to researchers working on kinetic models of atmospheric interest, in order to include Penning ionizations in their calculations as fast processes promoting reactions that cannot be neglected. Ions are extremely important for the transmission of radio and satellite signals, and they govern the chemistry of planetary ionospheres. Molecular ions have also been detected in comet tails. In this paper recent experimental results concerning production of simple ionic species of atmospheric interest are presented and discussed. Such results concern the formation of free ions in collisional ionization of H₂O, H₂S, and NH₃ induced by highly excited species (Penning ionization) as metastable noble gas atoms. The effect of Penning ionization still has not been considered in the modeling of terrestrial and extraterrestrial objects so far, even, though metastable helium is formed by radiative recombination of He⁺ ions with electrons. Because helium is the second most abundant element of the universe, Penning ionization of atomic or molecular species by He^*(2³S₁) is plausibly an active route of ionization in relatively dense environments exposed to cosmic rays. Full article

(This article belongs to the Special Issue Atmospheric Composition Observations)

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