Dry Deposition Velocity as an Indicator for SO2 Damage to Materials |
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Authors: | Frederick W Lipfert |
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Institution: | Environmental Consultant , Northport , New York , USA |
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Abstract: | Data from the literature on dry deposition of SO2 to various common materials in outdoor atmospheres are reviewed and presented in the context of a theoretical model. The model postulates two resistances to deposition: the aerodynamic resistance, controlled by atmospheric properties; and the surface resistance, controlled by the chemistry of the surface and its moisture layer. Since the dissolution of SO2 is sensitive to pH, buffering of the moisture layer by corrosion products is essential for SO2 deposition to continue. Thus, it is hypothesized that SO2 deposits preferentially on those surfaces that are sensitive to SO2 attack. Based on extant data, estimates of aerodynamic and surface resistances are derived from the literature and maximum "dry" deposition rates for SO2 are estimated. Such information could be used to formulate SO2 dose-response or "damage" functions for certain materials, based on short-term laboratory tests. |
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