Document Details
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Document Type |
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Article In Journal |
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Document Title |
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Weekday/weekend differences in ambient aerosol level and chemical characteristics of water-soluble components in the city centre الإختلاف فى المستويات البيئية لتركيز الجسيمات العالقة فى الهواء والخصائص الكيميائية لمكوناتها الذائبة فى الماء بين أيام العمل وعطلات نهاية الأسبوعِ فى وسط المدينة |
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Document Language |
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English |
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Abstract |
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Weekday and weekend ambient aerosol samples were collected from the city centre of Cairo, namely "Ramsis" during the summer season of the year 2006, and have been analyzed for water-soluble ionic species. The average concentrations of the total suspended particulate matter (TSP) and their water-soluble components were higher during weekdays than on weekends, indicating that the decreased traffic density on weekends leads to a decrease in the levels of the TSP and their water-soluble ionic species. The average concentrations of the TSP were 454 µg m-3 on weekdays and 298 µg m-3 on weekends. The weekday/weekend concentration ratios were 1.52 for TSP, 1.27 for SO42-, 1.64 for Cl-, 1.54 for NO3-, 1.17 for NH4+, 1.67 for Ca2+, 1.83 for Na+, 1.75 for K+ and 1.73 for Mg2+. City centre of Cairo has high levels of the TSP and their water-soluble ionic species compared with many polluted cities in the world. Among all of the measured water-soluble components, SO42- was the most abundant species followed by Ca2+ on weekdays and weekends. The average mass ratios of NO3-/SO42- in the TSP were 0.41 on weekdays and 0.34 on weekends, suggesting that the stationary source emissions were more predominant. The NH4+/SO42- molar ratios and its relation with the concentrations of TSP and Ca2+ during the weekdays and weekends indicate that the chemical form of sulfate and ammonium in aerosol particles varies with TSP and Ca2+ levels. At high TSP and Ca2+ levels, and NH4+/SO42- molar ratios less than one, SO42- in aerosol particles may be present as CaSO4 and (NH4)2SO4.CaSO4.2H2O, whereas it is expected to be present as (NH4)2SO4, (NH4)2SO4.CaSO4.2H2O and CaSO4 at low levels of TSP and Ca2+, and NH4+/SO42- molar ratios between 1 and 2. The mean pH values of the TSP were 7.65 on weekdays and 6.97 on weekends, indicating that aerosol particles brought a large amount of crustal species, and might alleviate the tendency of acidification. The relationships between the concentrations of acidic components (NO3- and SO42-) and basic components (NH4+, Ca2+ and Mg2+) on weekdays and weekends indicate that the acidity of aerosol particles is neutralized. Ca2+ and NH4+ are the most dominant neutralization substances in Cairo atmosphere. |
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ISSN |
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7483-7493 |
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Journal Name |
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Atmospheric Environment |
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Volume |
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42 |
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Issue Number |
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0 |
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Publishing Year |
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1429 AH
2008 AD |
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Article Type |
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Article |
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Added Date |
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Monday, August 22, 2011 |
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Researchers
| ممدوح إبراهيم خضير | Khoder, Mamdouh Ibraheim | Investigator | Doctorate | Khoder_55@yahoo.com |
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| pdf | Weekday weekend differences in ambient aerosol level and che |
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