Dry Deposition of Ammonia at Environmental Concentrations on Selected Plant Species |
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| Authors: | Viney P Aneja Hugo H Rogers Edward P Stahel |
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| Institution: | 1. General Electric Company , Schenectady , New York , USA;2. National Soil Dynamics Laboratory , Auburn , Alabama , USA;3. North Carolina State University , Raleigh , North Carolina , USA |
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| Abstract: | The deposition velocity of NH3 on six plant species at environmental concentrations has been studied in a dynamic plant gas exchange reactor. The total resistance to the transport of NH3 was studied. The aerodynamic resistance was determined directly by NH3 gas absorption in aqueous solutions at environmental concentrations in a two-phase gradientless reactor modeling the transfer processes through the stomata in a leaf. The concentration of NH3 in the gas phase ranged from 50 to 1000 ppb and the temperature varied from 25 to 30°C. The results for the deposition velocity for NH3, during the day, varied from 0.3 to 1.3 cm/s. The deposition velocities at night were about one order of magnitude smaller. These results are compared with estimates from the Frdssling equation which consistently yields higher values of the same order of magnitude. To determine accurate atmospheric transport models or global budget models, a variable deposition velocity should be used to account for the diurnal and seasonal variations in the surface resistance. |
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