Carbon atmospheric concentration

For some high growth-rate biomass species, the carbon dioxide concentration in the air among the leaves of the plant often is considerably less than that in the surrounding atmosphere. Photosynthesis may be limited by the carbon dioxide concentrations under these conditions when wind velocities are low and insolation is high. 

Carbon. Most of the Earth s supply of carbon is stored in carbonate rocks in the Hthosphere. Normally the circulation rate for Hthospheric carbon is slow compared with that of carbon between the atmosphere and biosphere. The carbon cycle has received much attention in recent years as a result of research into the possible relation between increased atmospheric carbon dioxide concentration, most of which is produced by combustion of fossil fuel, and the "greenhouse effect," or global warming. Extensive research has been done on the rate at which carbon dioxide might be converted to cellulose and other photosyntheticaHy produced organic compounds by various forms of natural and cultivated plants. Estimates also have been made of the rate at which carbon dioxide is released to soil under optimum conditions by various kinds of plant cover, such as temperature-zone deciduous forests, cultivated farm crops, prairie grassland, and desert vegetation. 

The toxic effects of chloroform resemble those of carbon tetrachloride. The probable effects of exposure to various atmospheric concentrations of chloroform are summarized in Table 4 (37). 

The most serious ha2ard of repeated exposure to chloroform inhalation is injury to the Hver and kidneys. Evidence indicates that in humans, repeated exposure to atmospheric concentrations well below the odor threshold may cause such injury. Industrial experience has shown that daily exposure to concentrations below 100 ppm may result in a variety of nervous system and alimentary tract symptoms, in the absence of demonstrable evidence of injury (39). Injury to the Hver is similar to but somewhat less severe than that caused by carbon tetrachloride. Kidney injury is usually associated with but less severe than Hver injury. 

The rollback approach assumes that emissions and atmospheric concentrations are linearly related, i.e., that a given percentage reduction in emission will result in a similar percentage reduction in atmospheric concentrations. This is most likely a valid assumption for a nonreactive gas such as carbon monoxide, whose principal source is the automobile. The model is... 

Just recently (Wilde et al. 2000), half a century after the indirect demonstration, it has at last become possible to see carbon atmospheres around dislocations in steel directly, by means of atom-probe imaging (see Section 6.2.4). The maximum carbon concentration in such atmospheres was estimated at 8 2 at.% of carbon. 

Figure 2a. Carbon dioxide concentrations in the atmosphere have varied over the glacial cycles of the earth s history, with high vjues at of around 300 during the interglacial period approximately 130,000 years ago...

An important issue that remains unresolved, because of the lack of adequate quantitative data on reservoirs and fluxes, is the location of the so called "missing" carbon. Missing carbon is the carbon added to the atmosphere from the burning of fossil fuel that cannot be accounted for by the measured increase in atmospheric concentration or by diffusion into the ocean (5). 

Carbon dioxide has been measured at more that 30 stations, and an annual fluctuation of atmospheric carbon dioxide concentration was observed at all (10), However, the magnitude and timing of the fluctuations varied with geographic location (11), At Mauna Loa observatory, the concentration of atmospheric CO2... 

Bacastow, R. B. and Keeling, C. D. (1981). Atmospheric carbon dioxide concentration and the observed airborne fraction. In "Carbon Cycle Modeling" (B. Bolin, ed.), pp. 103-112. Wiley, New York. 

Until recently, the distribution of carbon among the different terrestrial spheres was stable. When humans began burning fossil fuels, however, such burning transferred carbon into the atmosphere as CO2. This has become a rapidly changing feature of the overall carbon cycle. Over the last quarter century, the atmospheric concentration of CO2 has grown by more than 10%. 

Pearson, P.N. and Palmer, M.R. (2000) Atmospheric carbon dioxide concentrations over the past 60 million years. Nature, 406, 695-699. 

Its combustion does not contribute towards increasing the net atmospheric carbon dioxide concentration, one of the major factors responsible for the greenhouse effect ... 

Problems may arise when the atmospheric concentration of greenhouse gases increases. Since the beginning of the industrial revolution, atmospheric concentrations of carbon dioxide have increased nearly 30%, methane concentrations have more than doubled, and nitrous oxide concentrations have risen by about 15%. These increases have enhanced the heat-trapping capability of the earth s atmosphere. 

Yields of plant products grown in greenhouses can increase by 20% by enriching the air inside the greenhouse with carbon dioxide. The target level for enrichment is typically a carbon dioxide concentration of 800 ppm - or about two-and-a-half times the level present in the atmosphere (Figure 16). 

A full understanding will be needed of the complex chemistry by which the atmosphere and the earth interact, including the dependence of global climate on carbon dioxide concentrations in the atmosphere. Is there a way to deal with the carbon dioxide produced by burning coal and other hydrocarbon fuels so that it causes no problem Chemical scientists will need to investigate effective ways to trap C02 that would otherwise build up in the atmosphere. Alternatively, it will be necessary to find ways to reduce the generation of carbon dioxide. As human... 

There is also interest in finding feasible and harmless ways to capture and permanently sequester carbon dioxide underground or in the oceans, thereby preventing its accumulation in the atmosphere.2 Carbon dioxide concentration in the... 

In addition to climate change, the increased atmospheric concentration of C02 is likely to have wide-spread ecological effects in various environments, since C02 is a physiologically active gas, in plants as well as animals. The acidic nature of C02 will also lead to changes in the chemistry of the ocean s surface, which is in equilibrium with the atmosphere. Once the shift in the oceanic chemical balance becomes significant, it will affect ecosystems. It has been shown, for example, that doubling C02 concentration in the atmosphere will reduce the rate of calcium carbonate deposition in coral reefs by 30-40% (Langdon et al., 2000). 

The strong increase in atmospheric concentrations of carbon dioxide [ 127] has generated considerable interest in the global carbon cycle [ 128-130]. Techniques for determining the components of the carbonate system have been refined, new techniques have been developed, or both. Among the four measurable parameters (total inorganic carbon), pH, pC02, and total alkalinity... 

Figure 6-6 also shows the variation in the partial pressure of carbon dioxide in equilibrium with the lagoon s waters. The average value of this pressure exceeds the atmospheric value, 1, so on average, carbon dioxide is evaporating from the lagoon. The evaporation rate is greatest at times of maximum alkalinity and bicarbonate concentration and minimum carbonate ion concentration. 

Carbon cpntent of reservoirs atmosphere (SJ, biosphere (Nb), mixed layer (N,J, and ocean (N0J. R is the t4C concentration of C in the reservoir and atmospheric concentration is defined as 100 percent. The I4C concentrations are corrected for isotopic fractionation to a common 8,3C = —25 per mil. K is the eddy diflusivity, and S,aC is the i3C concentration deviation from a standard. 

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