O2 deficit

Medbo, J.I., Mohn, A.-C.,Tabata, I., Bahr, R., Vaage, 0., Sejersted,O.M. (1988). Anaerobic capacity determined by maximal accumulated O2 deficit. J. Appl. Physiol. 64, 50-60. 

Hanson, A.D. Jacobsen, J.V. (1984). Control of lactate dehydrogenase, lactate glycolysis and a-amylase of O2 deficit in barley aleurone layers. Plant Physiology, 75, 566-72. 

The amount of O2 deficit due to organic matter respiration in a water sample can be estimated by knowing the temperature, salinity, and O2 concentrations. The difference between the O2 calculated to be at equilibrium, [0 ], and the measured O2 value is called the apparent oxygen utilization or AOU ... 

The rate of O2 reaeration (the third term in Eq. 2.62) is proportional both to the O2 deficit, which is the difference between the saturated O2 concentration and the actual O2 concentration, and to the reaeration coefficient. The reaeration coefficient for oxygen equals the gas exchange velocity (the piston velocity) for oxygen divided by average stream depth (Section 2.3.2) thus, the gas exchange velocity equals the product of the reaeration coefficient and depth. Total flux [M/T] of atmospheric O2 into the control volume by reaeration is thus... 

In Amazon floodplain lakes, daily water column respiration usualiy exceeds planktonic gross photosynthesis, and dissolved oxygen is usually undersaturated (Melack and Fisher 1983). Wissmar et al. (1981) and Richey et al. (1988) found Amazon flood-plain lakes to be consistently undersaturated in O2 and supersaturated in CO2. The deficit of oxygen in these systems is a consequence of high respiration to production ratios. 

A second method used to calculate nitrate deficit takes advantage of the semiconservative water-mass tracer NO (Broecker, 1974). StoichiometricaUy, every mole of O2 respired wiU remineralize approximately 1/9 of a mole of NOJ so that NO, defined as... 

Figure 14.8 Vertical profiles of properties at 19°N, 67°E in the Arabian Sea (all data except for N2 collected onTN039 cruise of US JGOFS on 1-2/10/1994). (A) O2 (circles) and NOs (triangles) (B) N2O (circles) and N02 (triangles) (C) NOs deficit according to Codispoti et al. (2001) (dots connected by the solid line), N according to Gruber and Sarmiento (2002) (small filled triangles connected by the dashed line), and excess N2 calculated from the N2/Ar ratio (larger unconnected symbols - crosses for data collected on two different cruises from this site and triangles for those from other stations also located within the denitrification zone).

The concept of trapping a contaminant in low concentration by adsorption with periodic regeneration of the adsorbent-catalyst has been applied commercially by Toyota for NOx-trap catalysts used in converting NOx in diesel or lean burn engine emissions, for example, for reduction of NOx in the presence of O2 [63]. The catalyst acts as absorbent of NOx (in the form of surface nitrate-like species) in the presence of O2 (lean conditions), but a periodic switch of the air to fuel ratio to rich conditions (deficit of O2 with respect to stoichiometry for the complete oxidation of CO and hydrocarbons present in the car emissions to CO2) leads to regeneration by reducing trapped NOx to N2. 

Under equilibrium conditions the electrical conductivity of many oxide phases, e.g., CugO, FeO, CoO, NiO, or ZnO at elevated temperatures is a function of the oxygen partial pressure in the ambient gas phase 12). The oxygen partial pressure determines the metal excess or deficit in the metal oxide and thereby the concentration of electrical carriers especially excess electrons and electron holes. Thus, after proper calibration, the steady-state oxygen activity ao(st) may be deduced from measurements of the conductance of a metal oxide foil used as catalyst while an oxygen transfer reaction, e.g., CO2 + H2 = CO -)- HjO or 2N2O = 2N2 + O2 proceeds at the surface of the metal oxide 13). 

The dissociation energy of chemical compounds is in the order of 10 to 100 eV. Of course, such a compound can be expected to decompose if bombarded with keV ions. Part of the volatile products thus arising are pumped away with the sputtering gas so that the growing film shows a deficit of these components. This is why stoichiometric compound films as oxides, nitrides, sulphides, etc. usually can only be prepared by sputtering by the addition of small amounts of O2, N2, H2S, etc., to the sputtering gas, hence in a form of reactive sputtering which replaces the losses. 

Aminotriazole (2mM) was applied through the transpiration stream of excised pea seedlings held in a water-jacketed glass cuvette. Rates of net CO2 assimilation (A) and transpiration (E) were measured by conventional gas exchange techniques under different CO2 and O2 concentrations, with or without PGA added to the transpiration stream. Photosynthetic photon flux density (PPFD) was maintained at 500 /nmol m s temperature at 24 2°C and atmospheric vapour deficit at 1 kPa. Results were normalized to steady state assimilation rates prior to commencement of treatment. 

The O2 content displays substantial fluctuations (deficit to supersatu-... 

In the case of oxygen-depleted streams, such as typically occur downstream of wastewater outfalls, the flux of O2 is from the atmosphere into the streams. In a stream with steady, uniform flow and no sources or sinks of oxygen other than the atmosphere, an oxygen deficit decays exponentially with downstream travel time. The classic Streeter-Phelps model, discussed in Section 2.5, considers not only dissolution of O2 into a stream but also simultaneous O2 consumption due to microbial degradation of organic waste within the stream. By tradition, the reaeration coefficient in Streeter-Phelps modeling is designated fCoj. 

A certain lake becomes thermally stratified on May 15. The hypolimnion averages 4 m thick. Thereafter, O2 in the hypolimnion begins to decrease at a rate of 0.1 ppm/day. (This is called the hypolimnetic oxygen deficit, and it is commonly used as an index of a lake s biological productivity.) When bottles of the hypolimnetic water are incubated under temperature and light mimicking natural conditions, the daily O2 decrease in the bottles is 0.07 ppm and the rate of decrease seems to be constant for several days. 

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