CO2 release

When the steam is condensed, any CO2 released in the boiler re-dissolves in the condensate, making it slightly acidic and corrosive. Normally, boiler feedwater is softened and the boiler water pH is raised by addition of... 

Stuiver, M. and Quay, P. D. (1981). Atmospheric C changes resulting from fossil fuel CO2 release and cosmic ray flux variability. Earth Planet. Sci. Lett. 53, 349-362. 

Kerrick, D.M. and Caldeira, K. (1993) Paleoatmospheric consequences of CO2 released during early Cenozoic regional metamorphism in the Tethyan orogen. Chem. Geol., 108, 205-230. 

Soil contributes to a greater extent to total carbon storage than do above-ground vegetation in most forests (Johnson and Curtis 2001). The total amount of soil organic carbon (SOC) in the upper meter of soil is about 1500 x 1015 g C (Eswaran et al. 1993 Batjes 1996), and the global atmospheric pool of CO2 is about 750 x 1015 g C (Harden et al. 1992). The CO2 emission from soil into atmosphere is about 68.0-76.5 1015 g C per year, and this is more than 10 times the CO2 released from fossil fuel combustion (Raich and Potter 1995). Variations in SOC pools and SOM turnover rates, therefore, exert substantial impacts on the carbon cycles of terrestrial ecosystems in terms of carbon sequestration in soil and CO2 emission from soil. 

Uronic acids and pectic material have partly or mainly been dissolved and removed from commercial boards on pressurized refining. On heating wood they will contribute considerably to CO2 release (33). Organic acids such as formic and acetic acid are also split off from side chains of wood polymers. 

There are two factors of personnel hazard from a CO2 release ... 

Soil. When radio-labeled 4-aminopyridine was incubated in moist soils (50%) under aerobic conditions at 30 °C, the amount of CO2 released from an acidic loam (pH 4.1) and an alkaline, loamy sand (pH 7.8) was 0.4 and 50%, respectively (Starr and Cunningham, 1975). 

Carbon dioxide gas is an asphyxiant, a potent respiratory stimulant, and both a stimulant and depressant of the central nervous system. Fatalities have occurred after people have entered enclosures where air has been largely displaced by CO2. Therefore, fixed, automatic CO2 systems require a time delay pre-evacuation alarm period (often 30 seconds), warning signs, and an alarm signal incorporated into the system design to allow sufficient time for personnel evacuation prior to CO2 release. Verification of the oxygen level must be made prior to reentry. 

The respiratory quotient (RQ), which is the ratio of volume of O2 absorbed per hour to volume of CO2 released per hour, should ideally be 1 when the O2 supply is not limiting. It has been reported that the CO2 to O2 ratio value is approximately 0.8 during the early period of storage and 1.3 when sprout growth started (Burton, 1989 Gottschalk and Ezhekiel, 2006 Isherwood and Burton, 1975). 

Because of the large volume of CO2 released during the neutralization of propionic acid, care should be taken that the propionic acid is quenched before the reaction mixture is sealed and shaken inside a separatory funnel. 

The impact of humankind on the carbon cycle, evident in Figure 9.1, stems mainly from the release of CO2 to the atmosphere by fossil fuel burning and likely land use practices, such as deforestation and cultivation. Fossil fuel burning resulted in 1984 in the release of 444 x 1012 moles C to the atmosphere, or about 5% of the total CO2 released by natural processes of respiration and decay. Because of the small size of the atmospheric CO2 reservoir, this release can have a substantial effect on the CO2 concentration of the atmosphere. 

Figure 9.11. Rates of industrial CO2 emissions to the atmosphere (A) and cumulative CO2 release (B) for various future energy scenarios. (After US/USSR Workshop, 1981.)...

In Figure 9.21 all of the carbon eventually used in weathering of minerals by CC>2-charged soil water is shown as entering the atmosphere. The difference between the flux of CO2 owing to precipitation of carbonate minerals in the ocean and the total CO2 released from the ocean is that CO2 used to weather silicate minerals on land, and agrees with the calculations of riverine source materials made earlier in this chapter, in which it was shown that 30% of the HCC>3 in river water comes from weathering of silicate minerals. 

This increase in atmospheric CO2 concentration for the past 200 years is primarily a result of the increased flux of carbon gases (CO2, CO, CH4) to the atmosphere from the land because of the burning of fossil fuels and deforestation and cultivation practices of society. It is likely that land use fluxes were more important than fossil fuel sources in the 19th and early 20th century, but during much of the latter century fossil fuel CO2 releases appear to have been greater than... 

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