Difference In CO2 Concentration Research Articles

Oomoldic Porosity Experimentally Developed in Mississippian Oolitic Limestone

ABSTRACT Secondary fabric-selective porosity has been experimentally produced in the Ste Genevieve Limestone (Upper Valmeyeran, Mississippian, Illinois). Jacketed cylindrical specimens of the limestone were placed in a specially designed triaxial apparatus that permits circulation of pore fluid (CO2-charged water) under constant pressure while subjecting the rock specimen to constant vertical pressure, lateral confining pressure, and temperature. Burial conditions of about 10,000 ft (3,050 m) were simulated by an axial pressure of 10,150 psi (70 MPa), a lateral confuting pressure of 8,700 psi (60 MPa), and a pore pressure of 5,800 psi (40 MPa). All pressures were held constant throughout the tests and the temperature was maintained at 75° F (24° C). The results obtained indicate that fabric-selective secondary porosity can be developed in carbonate rocks by circulating fluids under conditions characteristic of deep burial, i.e., after pervasive cementation and after mineralogic stability have occurred. In the tested oolitic calcarenite, secondary porosity was developed and permeability was enhanced significantly by the centripetal preferential dissolution of the microporous cortical layers of the ooids, development of pore throats at the point contacts between ooids. and, ultimately, by the removal of nuclei to produce oomoldic porosity. Differences in CO2 concentration and flow rate of the fluid and in test specimen configuration had no observable influence on the dissolution effects, only on the solution rates.

CO2 and the cephalic direct current system: studies on humans and a biophysical analysis.

ABSTRACTThe TCDC/CO, hypothesis is that slowly changing potentials, source resistances and source currents, measured between electrodes placed over specific diploic/emissary vein distributions on the scalp, largely reflect regional differences in subelectrode CO2 concentrations which are in equilibrium with subjacent cortical differences in metabolism and CO2 production. Studies on humans show that TCDC parameters do show the expected relationships with the effects of regional differences in CO2 concentration.An explicit quantitative formulation of the hypothesis is developed based on the best available measures of all essential parameters, and it in shown that this model permits the correct computation of all TCDC empirical norms under essentially all conditions of measurement. Although it now appears that MIX studies have a substantial theoretical foundation it must be emphasized that the analysis in this paper is based on normative—i.e. averaged—values and cannot yet be applied to isolated TCDC measurements on single subjects.

Measuring Photosynthesis of Attached Leaves with Air Sealed Chambers 1

Net carbon exchange (NCE) of leaves is generally measured by sealing a chamber around an intact leaf. Most chambers use a flexible gasket around the leaf or petiole to insure an air-tight seal. This paper describes a chamber based on the principle that air provides a simple, effective seal. The chamber consists of three compartments: air-seal, leaf, and reference. The leaf is inserted through an opening in the air-seal compartment and into the leaf compartment. Air is pumped through an air supply tube into the air-seal compartments. It is then drawn through the leaf compartment and simultaneously through a reference compartment. NCE is determined from the difference in CO2 concentration in these two compartments. Enough excess air must be supplied to exhaust through the leaf port and provide an air seal about the leaf. This design allows repeated leaf insertion without injury even when measurements are taken for prolonged periods of time. This air seal is the primary advantage which adds simplicity, rapidity, and flexibility to the system.

The carbon‐dioxide flux over a field of sugar beet

AbstractThe difference of CO2 concentration at two heights above a sugar beet crop was measured with a sensitive infra‐red gas analyser. The ratio of evaporation to humidity gradient and of total heat flux to wet‐bulb temperature gradient gave a transport number for calculating CO2 flux, assumed proportional to CO2 gradient and wind speed. In August and September 1958 there was often a constant upward flux at night (mean 0·05 mg cm−2 hr−1) attributed to respiration by plants and soil micro‐organisms; but during daylight, photosynthesis gave a downward flux varying with solar radiation and reaching a maximum of 0·4 mg cm−2 hr−1. From 31 July to 11 September the net downward flux of atmospheric CO2 was 158 ± 29 mg cm−2 compared with an uptake of 217 ± 38 mg cm−2 estimated from dry matter increase of sampled plants. During October there was a net upward flux of 4·9 mg cm−2 day−1 attributed to a striking increase in amount of CO2 produced in the soil.