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 Title: Dry deposition of sulfate and nitrate to soybeans and corn Author(s): Dolske, Donald Arden Doctoral Committee Chair(s): Banwart, Wayne L. Department / Program: Crop Sciences Discipline: Crop Sciences Degree Granting Institution: University of Illinois at Urbana-Champaign Degree: Ph.D. Genre: Dissertation Subject(s): Agriculture, Agronomy Biology, Ecology Abstract: Dry deposition contributes a substantial part, perhaps one-third to one-half, of the total mass loadings of acidic pollutants and acid precursors to agricultural systems. However, because of the relative intractability of measurement of dry deposition fluxes, little work has been done to directly quantify these inputs of pollutants. Foliar surface sampling methods were developed and shown to be a practical and fairly precise means of monitoring the accumulation of dry-deposited SO$\sbsp{4}{2-}$ and NO$\sbsp{3}{-}$ on plant surfaces. Leaching of these ions from plant tissue was shown to be negligible; however, uptake by plants (e.g., stomatal gas exchange of SO$\sb2$ or HNO$\sb3$ and assimilation of surface accumulations of SO$\sbsp{4}{2-}$ and NO$\sbsp{3}{-}$) is not accounted for by the sampling method. The sulfur and nitrogen fluxes measured using the method thus underestimate the actual mass transfer from the atmosphere to the leaf. The significance of dry deposition to modification of the chemical microenvironment upon leaf surfaces appears to be a factor of 3 to 20 greater than that of wet deposition alone. This is due to the cyclic reactivation of accumulated materials by dew and light rains, which dissolve and mobilize, but do not remove, the pollutant deposit from the plant surface. Therefore, while dry deposition of SO$\sb2$ and SO$\sbsp{4}{2-}$ containing particles may contribute only half of the total mass of airborne sulfur inputs to crop systems, the exposure of plant surface tissue to pollutants can be dominated by the dry deposited material. Depending upon the nature of the particles deposited, the pH of water arriving at the leaf surface, e.g. acid rain, can be significantly altered. Changes in leaf surface chemistry may contribute to possible response mechanisms such as reduction of cuticular integrity, cellular injury and death, enhanced leaching of primary and secondary metabolites, and changes in pathogen infection efficiency. Issue Date: 1989 Type: Text Language: English URI: http://hdl.handle.net/2142/20084 Rights Information: Copyright 1989 Dolske, Donald Arden Date Available in IDEALS: 2011-05-07 Identifier in Online Catalog: AAI8916239 OCLC Identifier: (UMI)AAI8916239
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