Carbon cycle mineralization

The efficiency of the weathering of rocks in using carbonic acid produced in the carbon cycle is affected by various hydrologic, environmental, and cultural controls. The fact that the principal anion in fresh surface water worldwide almost always is bicarbonate attests to the overriding importance of this process. Exceptions are systems in which evaporite minerals are available for dissolution by groundwater or where human activities are major sources of sulfate or chloride inflow. 

Up to this point, we have focused on aqueous equilibria involving proton transfer. Now we apply the same principles to the equilibrium that exists between a solid salt and its dissolved ions in a saturated solution. We can use the equilibrium constant for the dissolution of a substance to predict the solubility of a salt and to control precipitate formation. These methods are used in the laboratory to separate and analyze mixtures of salts. They also have important practical applications in municipal wastewater treatment, the extraction of minerals from seawater, the formation and loss of bones and teeth, and the global carbon cycle. 

Goh KM, Haynes RJ (1986) Nitrogen and agronomic practice. In Haynes RJ (ed) Mineral nitrogen in the plant-soil system. Academic Press, Orlando, pp 379—468 Golchin A, Oades JM, Skjemstad JO, Clark P (1994) Soil structure and carbon cycling. Aust J Soil Res 32 1043-1068... 

This is a very sketchy depiction of the deep carbon cycle because it illustrates only the behaviors of calcium and silica. In reality, a wide variety of other cations are present in the silicate minerals, such as in the plagioclase feldspars (Table 13.2). Furthermore, not all of the limestone is converted into siUcate minerals some remains as limestone. Uplift of the limestone onto land, followed by chemical and biological weathering, is another sink for atmospheric CO2, via... 

Hayes JM (2001) fractionation of carbon and hydrogen isotopes in biosynthetic processes. In JW VaUey, DR Cole (eds,) Stable isotope geochemistry. Rev Miner Geochem 43 225-277 Hayes JM, Waldbauer JR (2006) The carbon cycle and associated redox processes through time, Phil Trans R,Soc B 361 931-950... 

Fauna also influence soil carbon cycling. Bioturbation mixes and aerates soil, physically breaks down litter, creates flow paths for water in soil, and can reduce surface litter stocks and enhance erosion (Bohlen et al., 2004). For example, along a gradient of European earthworm (Lumbricus terrestris) colonization in a deciduous forest of northern Michigan, earthworms are associated with a decrease in litter-layer thickness, apparently mixing some forest floor organic matter into the mineral soil. Thus, fauna can create spatial patterns in SOM stocks. 

To begin the discussion, we will present briefly a view of the modern carbon cycle, with emphasis on processes, fluxes, reservoirs, and the "CO2 problem". In Chapter 4 we introduced this "problem" here it is developed further. We will then investigate the rock cycle and the sedimentary cycles of those elements most intimately involved with carbon. Weathering processes and source minerals, basalt-seawater reactions, and present-day sinks and oceanic balances of Ca, Mg, and C will be emphasized. The modern cycles of organic carbon, phosphorus, nitrogen, sulfur, and strontium are presented, and in Chapter 10 linked to those of Ca, Mg, and inorganic C. In conclusion in Chapter 10, aspects of the historical geochemistry of the carbon cycle are discussed, and tied to the evolution of Earth s surface environment. 

Lomstein, B.A., Blackburn, T.H., and Henriksen, K. (1989) Aspects of nitrogen and carbon cycling in the Northern Bering shelf sediment. I. The significance of urea turnover in the mineralization of NH4+. Mar. Ecol. Prog. Ser. 57, 237-247. 

The chemoautotrophic fixation of C02 connected with this activity, only minimally contributes to the carbon cycling in most ecosystems. Notable exceptions to this include the deep-sea hydrothermal vent ecosystems, where the whole vent community is supported by the chemoautotrophic oxidation of reduced sulfur, primarily by Beggiatoa, Thiomi-cropira, and other sulfur oxidizers. In environments other than these, the generation of reduced minerals used in chemolithotrophic production is directly tied to the oxidation of photosynthetically produced organic matter. Therefore, sustainable primary production without solar energy input is unthinkable even in the case of chemolithotrophs. 

---