Mechanics, Materials Science & Engineering, July 2017 – ISSN 2412-5954
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Understanding the Nature of Wet Air Deposition on Rooftops in Uyo Metropolis
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Ihom A.P.1, Uko D.K. 1, Markson I.E. 1, Eleghasim O.C. 1
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1 – Department of Mechanical Engineering, University of Uyo, Uyo, PMB, Uyo, Nigeria
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a – ihom@uniuyo.edu.ng
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DOI 10.2412/mmse. provided by Seo4U.link
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Keywords: wet air, nature, pollutants, particulates, deposition, rooftops, Uyo metropolis.
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ABSTRACT. The work titled Understanding the Nature of Wet Air Deposition on Rooftops in Uyo Metropolis was Carried out by determining the extent of air pollution in four different places in Uyo metropolis. Attair 5X was used to determine the gaseous pollutants in the wet air, while filtration technique using High Volume Sampler was used to determine the suspended particulates in the air, and the concentration was calculated in mg/l over a 24hrs period. The composition of the deposition on the rooftops was analysed using EDX-X-Ray Fluorescence (EDX-XRF) and the characterization of the deposit was done using Scanning Electron Microscope (SEM). The result of the work showed that gas pollutants existed in all the four stations but were not to the level of health concern since air quality standard specifications were not exceeded. However, impact on rooftop was noted since SO3 was in the composition of the deposit on the rooftops. The suspended particulate matter exceeded air quality standard value of 200 µg/m3 in all the four stations, and so was of both health and environmental concern since it influenced the deposition on the rooftops. The SPM composition elements were also found in the composition of the deposits on the rooftops. SEM characterized the darkblack deposit on the rooftop and the micrograph showed areas of high and low deposition on the roofs. The study concluded that a better understanding of the nature of wet air deposition on rooftops in Uyo metropolis has now been established.
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Introduction. The quantity of atmospheric deposition depends on the amount and types of air pollutants emitted in the vicinity and upwind of a site [15], and the length of time between precipitation events [11]. A recent study of the Puget Sound Basin evaluated heavy metals, polycyclic hydrocarbons (PAHs), and other compounds in wet and dry atmospheric depositions. This study found that concentrations of the chemicals of concern in the highly urbanized area sampled were an order of magnitude greater than outside the urban area [17]. To differentiate between materials leaching and air deposition, recent studies have attempted to control for the contribution of air deposition, thereby evaluating the concentrations that leach from the roofing materials themselves.
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Wet and dry deposition contributes to the contaminants from commercial, residential and industrial roofs. Plate I with dark-black deposit on the rooftop is a typical building in Uyo metropolis. Contaminants associated with wet air deposition on rooftops comprise a portion of roof runoff. For example, Sabin [10] found that more than 50% of the metals in storm water runoff in Los Angeles were associated with air deposition. In a Swiss study, the ratio of the concentrations of metals in runoff compared to wet and dry atmosphere deposition ranged from as high as 27: 1 for copper to less than 1:1 for zinc depending on the roofing type and the location [16].
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© 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/
MMSE Journal. Open Access www.mmse.xyz