Characteristics of gas–phase nitric acid and ammonium–nitrate– sulfate aerosol, and their gas–phase precursors in a suburban area in Cairo, Egypt

Hassan, Salwa K.; El–Abssawy, Ahmed A.; Khoder, Mamdouh I.

doi:10.5094/apr.2013.012

Cited by 31 publications

(19 citation statements)

References 94 publications

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“…The average concentration of NH + 4 in PM 2.5 was higher than that observed at the rural or urban sites in the NCP (Meng et al, 2011), the YRD (Meng et al, 2014), Beijing , Guangzhou (Hu et al, 2008), and Hong Kong (Yao et al, 2006) in China, and is comparable to that at the urban site in India (Behera and Sharma, 2010). The average concentration of SO 2− 4 in PM 2.5 was higher than that at rural sites in the NCP (Meng et al, 2011) and YRD (Meng et al, 2014) in China, but was lower than that observed at rural sites in Guangzhou (Hu et al, 2008) in China as well as urban sites in India (Behera and Sharma, 2010) and Egypt (Hassan et al, 2013). The average concentration of NO − 3 in PM 2.5 was higher than that observed at the rural sites in the YRD and Guangzhou (Hu et al, 2008) in China and lower than that at urban sites in India (Behera and Sharma, 2010) and Pakistan (Biswas et al, 2008).…”

Section: Overview Of Concentration Levels Of Measured Speciesmentioning

confidence: 81%

“…Because of a series of emission reduction measures implemented in recent years, SO 2 levels have decreased markedly in the NCP . The average concentration of NO x was higher than that at the Shangdianzi (Meng et al, 2011) and Lin'an (Meng et al, 2014) regional background stations in the NCP and YRD region of China, which might be due to emissions from agricultural activities and motor vehicle sources (Lei and Wuebbles, 2013;Liu et al, 2013) in the NCP, but it was lower than those at urban sites in India (Behera and Sharma, 2010) and Egypt (Hassan et al, 2013).…”

Section: Overview Of Concentration Levels Of Measured Speciesmentioning

confidence: 83%

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Role of ambient ammonia in particulate ammonium formation at a rural site in the North China Plain

et al. 2018

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Abstract. The real-time measurements of NH 3 and trace gases were conducted, in conjunction with semi-continuous measurements of water-soluble ions in PM 2.5 at a rural site in the North China Plain (NCP) from May to September 2013 in order to better understand chemical characteristics of ammonia and the impact of secondary ammonium aerosols on formation in the NCP. Extremely high NH 3 and NH + 4 concentrations were observed after a precipitation event within 7-10 days following urea application. Elevated NH 3 levels coincided with elevated NH + 4 , indicating that NH 3 likely influenced particulate ammonium mass. For the sampling period, the average conversion / oxidation ratios for NH + 4 (NHR), SO 2− 4 (SOR), and NO − 3 (NOR) were estimated to be 0.30, 0.64, and 0.24, respectively. The increased NH 3 concentrations, mainly from agricultural activities and regional transport, coincided with the prevailing meteorological conditions. The high NH 3 level with NHR of about 0.30 indicates that the emission of NH 3 in the NCP is much higher than needed for aerosol acid neutralisation, and NH 3 plays an important role in the formation of secondary aerosols as a key neutraliser. The hourly data obtained were used to investigate gas-aerosol partitioning characteristics using the thermody-

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Section: Overview Of Concentration Levels Of Measured Speciesmentioning

confidence: 81%

Section: Overview Of Concentration Levels Of Measured Speciesmentioning

confidence: 83%

Role of ambient ammonia in particulate ammonium formation at a rural site in the North China Plain

et al. 2018

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“…Gas-phase chemical reactions that form secondary pollutants are also temperature dependent. Higher (lower) air temperatures in general lead to higher (lower) photolysis reaction rates and atmospheric oxidation rates, which enhance the production of tropospheric O 3 , secondary inorganic aerosols (e.g., nitrate, sulfate, and ammonium aerosols) and SOA (Aw and Kleeman, 2003;Hassan et al, 2013). In addition, concentrations of semi-volatile compounds are affected by equilibrium vapor pressure under various temperature conditions (Pankow, 1997;Ackermann et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

Effects of urbanization on regional meteorology and air quality in Southern California

Zhang

Sailor

et al. 2019

Atmos. Chem. Phys.

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Urbanization has a profound influence on regional meteorology and air quality in megapolitan Southern California. The influence of urbanization on meteorology is driven by changes in land surface physical properties and land surface processes. These changes in meteorology in turn influence air quality by changing temperature-dependent chemical reactions and emissions, gas-particle phase partitioning, and ventilation of pollutants. In this study we characterize the influence of land surface changes via historical urbanization from before human settlement to the present day on meteorology and air quality in Southern California using the Weather Research and Forecasting Model coupled to chemistry and the single-layer urban canopy model (WRF-UCM-Chem). We assume identical anthropogenic emissions for the simulations carried out and thus focus on the effect of changes in land surface physical properties and land surface processes on air quality. Historical urbanization has led to daytime air temperature decreases of up to 1.4 K and evening temperature increases of up to 1.7 K. Ventilation of air in the LA basin has decreased up to 36.6 % during daytime and increased up to 27.0 % during nighttime. These changes in meteorology are mainly attributable to higher evaporative fluxes and thermal inertia of soil from irrigation and increased surface roughness and thermal inertia from buildings. Changes in ventilation drive changes in hourly NO x concentrations with increases of up to 2.7 ppb during daytime and decreases of up to 4.7 ppb at night. Hourly O 3 concentrations decrease by up to 0.94 ppb in the morning and increase by up to 5.6 ppb at other times of day. Changes in O 3 concentrations are driven by the competing effects of changes in ventilation and precursor NO x concentrations. PM 2.5 concentrations show slight increases during the day and decreases of up to 2.5 µg m −3 at night. Process drivers for changes in PM 2.5 include modifications to atmospheric ventilation and temperature, which impact gas-particle phase partitioning for semi-volatile compounds and chemical reactions. Understanding process drivers related to how land surface changes effect regional meteorology and air quality is crucial for decision-making on urban planning in megapolitan Southern California to achieve regional climate adaptation and air quality improvements.Published by Copernicus Publications on behalf of the European Geosciences Union.

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“…The oxidation process of almost all sulfur compounds (including reduced sulphur species) are initiated by OH (Finlayson-Pitts and Pitts, 2000; Hassan et al, 2013). In general low SO 2 amounts are observed in summer (due to high OH productivity) compared to high amounts in winter (less OH productivity).…”

Section: Seasonal Variationmentioning

confidence: 99%

Spatio-Temporal Analyses of Atmospheric Sulfur Dioxide Column Densities over Pakistan by Using SCIAMACHY Data

Khartak

Khokhar

Yasmtn

2014

Aerosol Air Qual. Res.

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This paper presents the results of atmospheric Sulfur dioxide (SO 2 ) column densities obtained from satellite observation over Pakistan during the time period of 2004-2012. The level-2 data product of the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) instrument on-board ENVISAT-1 is used. SO 2 column densities are retrieved by applying differential optical absorption spectroscopy (DOAS) technique. The spatio-temporal distribution of SO 2 column densities along with the seasonal variation over main cities and regions of Pakistan are discussed. The Nabro volcano eruption in the year 2011 caused high SO 2 levels over East Africa, the Middle East and South and Southeast Asia. Satellite images exhibited several episodes of volcanic SO 2 column densities transported to Pakistan. The temporal trend in SO 2 column densities was calculated, and the significance of the data set was tested with statistical analysis. An overall increase of about 70% (8.7% per year) in SO 2 column densities over Pakistan during the time period of 2004-2012 has been calculated. This study presents the first spatial and temporal analyses of SO 2 column densities over Pakistan by using satellite observation.

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Characteristics of gas–phase nitric acid and ammonium–nitrate– sulfate aerosol, and their gas–phase precursors in a suburban area in Cairo, Egypt

Cited by 31 publications

References 94 publications

Role of ambient ammonia in particulate ammonium formation at a rural site in the North China Plain

Role of ambient ammonia in particulate ammonium formation at a rural site in the North China Plain

Effects of urbanization on regional meteorology and air quality in Southern California

Spatio-Temporal Analyses of Atmospheric Sulfur Dioxide Column Densities over Pakistan by Using SCIAMACHY Data

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