Fossil fuels deposits

The richest fossil fuel deposits are thought to occur at times when the earth was much warmer and contained much more C02 than today. 

The crust is the largest carbon reservoir in the crustal-ocean-atmosphere factory (8 x 10 Pg C including the sediments). Most of this carbon is in the form of inorganic minerals, predominantly limestone, with the rest being organic matter, predominantly contained in shale and secondarily in fossil fuel deposits (coal, oil, and natural gas). The oceanic reservoir (4 X lO" Pg C) and the terrestrial reservoir (2 to 3 x 10 Pg C) are both far smaller than the crustal reservoir. The smallest reservoir is found in the atmospheric, primarily as CO2 (preindustrial 6 x 10 Pg C, now 8 x 10 Pg C and rising). The flux estimates in Figure 25.1 have been constrained by an assumption that the preindustrial atmospheric and oceanic reservoirs were in steady state over intermediate time scales (millennia). 

Fossil fuel deposits are not distributed evenly throughout the world. For instance, 65 percent of the world s recoverable petroleum deposits are in the Middle East, along with 34 percent of recoverable natural gas deposits. North America is relatively poor in petroleum and natural gas but has a bit more than one-fourth of the world s supply of coal. 

The transition elements are useful tracers in many geological systems. They are industrially important and form economic ores, especially in hydrothermal systems where they are often present as sulfide minerals. Cd, Hg, Zn, and Pb are persistent industrial pollutants and determination of low levels of these elements in ores and fossil fuels is critical as processing of ores or burning of fuels may concentrate and release toxic elements. The concentration of such toxic trace elements may affect the economic value of an ore or fossil fuel deposit significantly. 

Despite the fact that they are chemically identical, it is possible to analytically identify bio-based plastics apart from identical fossil fuel-based plastics. Carbon dioxide in air has two isotopic forms of carbon, CO and CO, in equilibrium with each other, and plastics derived from plant sources will therefore have both these isotopes. Any isotopic carbon in fossil fuel deposits, however, had long decayed over the millions of years since their formation (half-life of C is 5730 years) into C and fossil fuels, and plastics made from them do not have significant levels of Burning a sample of plastic and measuring the ratio in the CO using liquid scintillation counting or isotope-ratio mass spectrometry therefore provide a test as to the origin of the plastic (ASTM D 6866). 

Fossil Fuels Deposits within the Earth s crust of either solid (coal), liquid (oil), or gaseous (natural gas) hydrocarbons produced through the natural decomposition of organic material (plants and animals) over many millions of years. These deposits contain high amounts of carbon, which can be burned with oxygen to provide heat and energy. 

Currently Aere is about 15 times as much carbon locked into fossil fuel deposits as there is present in the atmosphere. These deposits were caused by past imbalances in the carbon cycle. The burning of coal and oil since the Industrial Revolution has released much carbon, measurably changing man s environment. 

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