Carbon dioxide sinks

Hesshaimer V., Heimann M., and Levin I. (1994) Radiocarbon evidence for a smaller oceanic carbon-dioxide sink than previously believed. Nature 370, 201-203. 

Oechel W. C., Hastings S. J., Vourlitis G., Jenkins M., Riechers G., and Grulke N. (1993) Recent change of arctic tundra ecosystems from a net carbon dioxide sink to a source. Nature 361, 520—523. 

Explain why balloons filled with helium rise in air but balloons Med with carbon dioxide sink. 

FIGURE 17.16 Sources of carbon dioxide emission in the United States. Note that not all of the emitted CO2 enters the atmosphere. Some of it is taken up by carbon dioxide sinks," such as the ocean. 

Carbon dioxide sinks Atmospheric increase Oceanic uptake... 

Fan, S., Gloor, M., Mahlman, J., Pacala, S., Sarmiento, ]., Takahashi, T., and Tans, P. (1998). A large terrestrial carbon sink in North America implied by atmospheric and oceanic carbon dioxide data and models. Science 282, 442-446. 

Carbon dioxide is likewise an inert material. As a result, its only known sinks are photosynthesis and solubility in seawater. The cycle of carbon dioxide through the atmosphere will be a major focal point in Chapter 11. 

Fig. 11-16 Partial pressure of CO2 in surface ocean water along the GEOSECS tracks (a) the Atlantic western basin data obtained between August 1972 and January 1973 (b) the central Pacific data along the 180° meridian from October 1973 to February 1974. The dashed line shows atmospheric CO2 for comparison. The equatorial areas of both oceans release CO2 to the atmosphere, whereas the northern North Atlantic is a strong sink for CO2. (Modified with permission from W. S. Broecker et al. (1979). Fate of fossil fuel carbon dioxide and the global carbon budget, Science 206,409 18, AAAS.)...

Randerson, J. T., Thompson, M. V., Conway, T. J., Fung, I. Y. and Field, C. B. (1997). The contribution of terrestrial sources and sinks to trends in the seasonal cycle of atmospheric carbon dioxide. Global Biogeochem. Cycles 11,535-560. 

Tans, P. P., Conway, T. J. and Nakazawa, T. (1989). Latitudinal distribution of the sources and sinks of atmospheric carbon dioxide derived from surface observations and an atmospheric transport model, /. Geophys. Res. 94, 5151-5172. 

It is estimated that photosynthesis is a sink for around 60 billion tons of carbon every year, by far the strongest mechanism for carbon dioxide removal from the atmosphere. (This removal is almost exactly balanced by the respiration of animals, which combines oxygen with hydrocarbons to produce carbon dioxide and water vapor.)... 

The amount of carbon dioxide in the atmosphere is proportional to the partial pressure. Thus if partial pressure is expressed in units of the present level, the amount will become 56 X 1015 pco2 moles, where pco2 is the partial pressure of carbon dioxide. Expressing the reservoir in units of 1015 moles and the exchange rate in 1015 moles/y, the equation for the time rate of change of carbon dioxide partial pressure, assuming no other sources or sinks, becomes... 

We take K = 113 mol kg"1 atm-1. At steady-state, which we note with the superscript pt=3 x 10-4atm, x = 10.3 x 10 3molkg 1, xrt=3.6x 10-4molkg-1. Since in this model CaC03 is the only sink of carbon dioxide, xrt = yrt at steady-state, and therefore yr=yrf=3.6 x 10 4. This is enough to estimate the weathering constant K from equation (7.4.21)... 

Resources such as biomass could provide a clean and sustainable resource for hydrogen production. As with fossil fuels, the processes that produce hydrogen gas from biomass all create carbon dioxide, but because the biomass acts as a carbon sink during the growing phase, the net carbon emission of the whole cycle is neutral. 

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