Document Type

Technical Report

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Dew, chemistry, flux, atomspheric chemistry, Northwest Arkansas


From July, 1989 to July 1990 a total of 98 dews and 9 frosts were collected at the University of Arkansas Agricultural Experiment Station, Fayetteville. The total water flux from dews and frosts per year is less than 2% of that from rains. Acid and nutrient fluxes are also much lower in dew. In the following series of ions the number in parenthesis gives the % of the yearly flux of the ion in dew compared to rain for an average year: H+ (0.08), Ca2+ (23), Mg2+(9), K+(20), Na+(5), NH+(12), Cl-(7), S02/4-(5) and N0-/3 (6). A typical dew has a pH of 6.25 compared to 4.9 for the average rain, and is thus much less acidic. Acetate and formate ions in the April-June period were, in equivalents, higher in dew than in the rain and equal to about one half of the nitrate-sulfate total. The steps governing dew composition are indicated to be (1) nucleation on dry-deposition solids identified as illite, kaolinite, quartz, feldspar, calcite, and dolomite (2) dissolving the soluble portion of the dry deposition by dew water and (3) dissolving of gaseous NH3, acetic, and formic acids into the dew solution.

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