Photosynthesis global

Boichenko, V.A., Greenbaum, E., and Seibert, M. 2004. Hydrogen production by photosynthetic microorganisms, in Photoconversion of Solar Energy Molecular to Global Photosynthesis, M.D. Archer and J. Barber, eds., Imperial College Press, London, pp. 397-452. 

In normal times the air is more oxidized than fresh volcanic rock, and also more oxidized than the sediment column, which is enriched in reduced organic matter. Before the onset of global photosynthesis this contrast with the sediment may have been very different (Walker 1987), especially if methane were abundantly released (Hayes 1994). 

Photosynthesis (Scheme 1.2) is the source of food and fossil fuel and has played an important role in the origin of life.a A fully grown beech tree assimilates about 10 m3 of C02 (contained in 4 x 104 m3 of air) on a sunny day, producing the same amount of 02 and 12 kg of carbohydrates. Globally, photosynthesis stores about 2 x 10121 of C02 in biomass per year, the equivalent of 2 x 1019kJ, most of which, however, is eventually returned to the atmosphere by reoxidation. 

The balance between P and R is responsible for regulating the concentration of 02 in the oceans and the atmosphere (27). Thus, biological processes in the sea (probably more than half of the total global photosynthesis takes place in the sea) regulate po2 and in turn the redox intensity of the interface between atmosphere and hydrosphere. 

Archer, M. D. and J. Barber (2004) Molecular to global photosynthesis. World Scientific Publ. Co., 788 pp. 

Holzwarth AR (2004) In Barber J (ed) Molecular to Global Photosynthesis. Imperial College Press, London, pp 43-115... 

Of course, the bulk of the global photosynthesis turnover goes through the chloro-plasts of green plants, with the photosynthetic reaction center entirely unrelated to rhodopsins. 

One of the most abundant marine phytoplankton is a tiny microbe called Proc/i/orococcM5. Twenty years ago, no one knew Prochlorococcus even existed, until it was discovered by Penny Chisholm and her team at MIT. Now, we know that Prochlorococcus is responsible for about one-fifth of global photosynthesis. Simply amazing With the modern tools of oceanography, genomics, and analytical chemistry, we re learning a lot about what Prochlorococcus and other marine phytoplankton need to grow and to thrive. One of those key requirements is acquisition of transition metals, such as iron and cobalt. 

In cyanobacteria and the eukaryotic photosynthetic cells of algae and higher plants, HgA is HgO, as implied earlier, and 2 A is O,. The accumulation of O, to constitute 20% of the earth s atmosphere is the direct result of eons of global oxygenic photosynthesis. 

Rate constants for a large number of atmospheric reactions have been tabulated by Baulch et al. (1982, 1984) and Atkinson and Lloyd (1984). Reactions for the atmosphere as a whole and for cases involving aquatic systems, soils, and surface systems are often parameterized by the methods of Chapter 4. That is, the rate is taken to be a linear function or a power of some limiting reactant - often the compound of interest. As an example, the global uptake of CO2 by photosynthesis is often represented in the empirical form d[C02]/df = —fc[C02] ". Rates of reactions on solid surfaces tend to be much more complicated than gas phase reactions, but have been examined in selected cases for solids suspended in air, water, or in sediments. 

Rainwater and snowmelt water are primary factors determining the very nature of the terrestrial carbon cycle, with photosynthesis acting as the primary exchange mechanism from the atmosphere. Bicarbonate is the most prevalent ion in natural surface waters (rivers and lakes), which are extremely important in the carbon cycle, accoxmting for 90% of the carbon flux between the land surface and oceans (Holmen, Chapter 11). In addition, bicarbonate is a major component of soil water and a contributor to its natural acid-base balance. The carbonate equilibrium controls the pH of most natural waters, and high concentrations of bicarbonate provide a pH buffer in many systems. Other acid-base reactions (discussed in Chapter 16), particularly in the atmosphere, also influence pH (in both natural and polluted systems) but are generally less important than the carbonate system on a global basis. 

Oxidation-reduction reactions in water are dominated by the biological processes of photosynthesis and organic matter oxidation. A very different set of oxidation reactions occurs within the gas phase of the atmosphere, often a consequence of photochemical production and destruction of ozone (O3). While such reactions are of great importance to chemistry of the atmosphere - e.g., they limit the lifetime in the atmosphere of species like CO and CH4 - the global amount of these reactions is trivial compared to the global O2 production and consumption by photosynthesis and respiration. 

If the global oxygen production caused by the small fraction of carbon fixed by photosynthesis that is buried were not balanced by an oxygen consumption term, and other processes remained the same, the O2 content of the atmosphere would roughly double in about 2 million years. This is a short time geologically, particularly because it is believed there has been... 

Algae have the ability to directly utilize sunlight and carbon dioxide for photosynthesis. Due to this activity, cyanobacteria may help to solve a global environmental problem, the greenhouse effect, which increasingly threatens mankind at the beginning of the 21st century. 

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