Diurnal and seasonal variations in the carbon dioxide concentration of the lower atmosphere in the coastal plain of Israel

Enoch, H. Z.

doi:10.1016/0002-1571(77)90033-4

Cited by 6 publications

(2 citation statements)

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“…the severity of the error introduced by this assumption. Also, neither Businger ( 1963) nor Acock and A cock ( 1989) accounted for fluctuating ambient [C0 2 ) outside the chamber, which could be a serious limitation considering that the tim~ recommended by Acock and Acock ( 1989) for making the determinations is just before dawn when r~spiration is steady, but also when ambient C0 2 concentrations are quite variable (Allen, 1968(Allen, , 1971Enoch, 1977;Kimball et al, 1984), exc~pt possibly in winter.…”

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confidence: 99%

“…Kimball et al (1984), for example, showed that the standard deviation in observations of[C0 2 ] in a cotton field was ab<;mt 150 ~-tmol mol-1 at night compared to 75 ~-tm~l mol-1 dunng daytime. On a calm night in the Coastal Plam of Israel, the graph of Enoch (1977) shows changes of 100 ~-tmol mol-1 within 1 h. Allen (1971) showed how [C0 2 ] in a com (Zea mays) field can increase from about 300 to 450 ~-tmol mol-1 or more under calm conditions at night, and that under these conditions it is very sensitive to slight increases in wind speed. The data of Allen ( 1968) sh<;>w th~t usually the change in concentration from one 15-mm penod to the next was less than 10 ~-tmol mol-1 , but changes greater than 30 were not uncommon.…”

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Exact Equations for Calculating Air Leakage Rates from Plant Growth Chambers

Kimball¹

1990

Agronomy Journal

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The rates of leakage of CO2 from plant assimilation chambers must be known in order to correct measurements of net photosynthesis and respiration for this unwanted but omnipresent source of error. Similarly, in order to precisely calculate heating or cooling requirements for plant growth structures, air leakage or “infiltration” must be known. The objective of this paper is to derive theoretically exact equations for calculating such leakage rates from measurements of CO2 concentration [CO2]. The needed equations were derived from the solution of a basic differential CO2 balance equation. The procedure presumes the determination will be done when plant CO2 exchange is steady, a condition most nearly satisfied by respiration near the end of the night. The equation had two unknowns, respiration and leakage rate. From measurements before and after a CO2 perturbation, it was possible to derive sets of two equations with two unknowns, which were then solved for the respiration and leakage rates. In contrast to prior work, the new equations are theoretically exact, and they can account for changes in ambient [CO2] during the measurement periods and also for differing rates of CO2 injection before and after the perturbation. Moreover, these theoretically exact equations are no more complex than the prior approximate equations for a couple of practical cases. Calculations for three specific cases showed the approximation used in the prior equations introduced errors of 0.8, 5.5, and 1.6%. Thus, using these equations derived in this paper should permit more accurate calculations of leakage rate and ultimately, therefore, more accurate determinations of gas exchange rates from plants in assimilation chambers as well as of the heating or cooling requirements of the chambers themselves.

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confidence: 99%