Carbon compounds oceanic reservoirs

While radiocarbon is not nearly as valuable to this exercise as it is in the case of the ocean, it does have a role to play. More than half of the terrestrial carbon inventory is stored in soils. The humus in soils consists of a host of complex organic compounds. The evolution of storage in this reservoir will be driven by two competing impacts. Increasing planetary temperature will lead to more rapid oxidation of these humic compounds and hence will tend to drive down the planetary inventory. In contrast, increasing plant growth will lead to increased storage of new humic compounds and hence tend to drive up the inventory. 

The vast majority of carbon is found in sedimentary rocks as inorganic carbonate minerals and solid organic compounds, and in the deep interior as carbon dioxide and methane. The global carbon cycle can therefore be envisioned as the long-term transfer of deep crustal and mantle carbon to shallow crustal sediment reservoirs via the ocean/atmosphere system, where carbon is parsed into several reservoirs through reactive pathways that modify the initial carbon isotopic value of the outgassed carbon. The... 

Fig. 5.4 Oxygen in chemical reservoirs and chemical cycling numbers represents total mass of oxygen in 10 g (CO2 is almost as carbonate dissolves in ocean and O2 molecular in air), (CH20)n represents organic compounds including biomass.

A sink is a reservoir that uptakes a chemical element or compound from another part of its cycle. For example, soil and trees tend to act as natural sinks for carbon, as billions of tons of carbon each year in the form of CO2 are absorbed by oceans, soils, and trees. The EU-15 countries had agreed to cut, by 2012, 8% of the 1990 values, but the data collected in late 2006 by the European Commission predict that the values will be only 0.6% below the base year levels by 2010. Worse still, Austria, Belgium, Denmark, Ireland, Italy, Portugal, and Spain may even exceed their individual limits. 

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