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Radon as a natural tracer of gas transport through trees
Author(s) -
Megonigal J. Patrick,
Brewer Paul E.,
Knee Karen L.
Publication year - 2020
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.16292
Subject(s) - soil gas , tracer , transpiration , environmental science , atmosphere (unit) , soil water , trace gas , radon , sink (geography) , atmospheric sciences , soil science , hydrology (agriculture) , environmental chemistry , chemistry , geology , physics , meteorology , photosynthesis , geography , quantum mechanics , biochemistry , cartography , geotechnical engineering , nuclear physics
Summary Trees are sources, sinks, and conduits for gas exchange between the atmosphere and soil, and effectively link these terrestrial realms in a soil–plant–atmosphere continuum. We demonstrated that naturally produced radon‐222 ( 222 Rn) gas has the potential to disentangle the biotic and physical processes that regulate gas transfer between soils or plants and the atmosphere in field settings where exogenous tracer applications are challenging. Patterns in stem radon emissions across tree species, seasons, and diurnal periods suggest that plant transport of soil gases is controlled by plant hydraulics, whether by diffusion or mass flow via transpiration. We establish for the first time that trees emit soil gases during the night when transpiration rates are negligible, suggesting that axial diffusion is an important and understudied mechanism of plant and soil gas transmission.