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Measurements of soil and canopy exchange rates in the Amazon rain forest using Rn-222Measurements were taken of the emission of Rn-222 from Amazon forest rocks and soils and used as a tracer of ventilation of the forest canopy layer at night. It was determined that the greatest resistance to transfer of trace gases from the soil to the atmosphere lies in the soil air space. Profiles of Rn-222 and CO2 showed steepest concentration gradients in the layer between 0 and 3 m above soil surface. Aerodynamic resistances calculated for this layer from Rn-222 and CO2 varied from 1.6 to 18 s/cm, with greater resistance during the afternoon than at night. The resistance to exchange with air from the entire 41 m layer below the canopy averaged 4.8 s/cm during 13 nights of CO2 profiles. The calculated average time to flush the layer below 41 m is 5.5 hr, and it is concluded that this indicates that significant exchange occurs despite nocturnal stratification.
Document ID
Document Type
Reprint (Version printed in journal)
Trumbore, S. E.
(Lawrence Livermore National Laboratory Livermore CA, United States)
Keller, M.
(NCAR Boulder, CO, United States)
Wofsy, S. C.
(Harvard University Cambridge, MA, United States)
Da Costa, J. M.
(Vicosa, Universidade Federal, Brazil)
Date Acquired
August 14, 2013
Publication Date
September 20, 1990
Publication Information
Publication: Journal of Geophysical Research
Volume: 95
ISSN: 0148-0227
Subject Category
Environment Pollution
Accession Number
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