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Line Source Carbon Dioxide Release. I. Field Experiment 1
Author(s) -
Allen L. H.,
Desjardins R. L.,
Lemon E. R.
Publication year - 1974
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1974.00021962006600050004x
Subject(s) - carbon dioxide , environmental science , atmospheric sciences , tracer , turbulence , turbulent diffusion , atmosphere (unit) , canopy , eddy covariance , chemistry , meteorology , geology , physics , botany , ecology , organic chemistry , ecosystem , nuclear physics , biology
Carbon dioxide gas was released from one northeastsouthwest line in a corn ( Zea mays L.) field during several days in August and September, 1969. CO 2 concentration profiles were measured at 15 and 45 m downwind. The purposes of the releases were: (1) to study the micrometeorological transport processes in plant canopies using CO 2 , as a tracer, and (2) to determine the micrometeorological feasibility of CO 2 enrichment under field conditions. The study showed that vertical turbulent diffusion and horizontal mass flow quickly diminished the concentration of CO 2 , downwind from the line source. High concentrations of CO 2 could be maintained in the canopy only under a stable temperature stratification of the air which reduced vertical wind fluctuations. Short‐term eddies with CO 2 concentrations in excess of 1,000 ppm were observed 30 m downwind from the release line at an analyzer height of 530 cm, but these were very infrequent. CO 2 concentration profiles showed that CO 2 tended to be turbulently diffused upward and wafted downwind, with some of the CO 2 being again transported into the canopy. Turbulent diffusion in the canopy was usually too active to maintain a high CO 2 concentration; however, this same effectiveness of turbulence assures an adequate supply of CO 2 to plant canopies under typical field conditions. This study showed, from a micrometeorological viewpoint, that CO 2 enrichment would not be practical under most natural field and crop conditions because of rapid gaseous exchange with the bulk atmosphere.