Sangeetha Pulapaka
0

All life is based on the element carbon. Carbon is the major chemical constituent of most organic matter, from fossil fuels to the complex molecules that control genetic reproduction in organisms. Yet by weight, carbon is not one of the most abundant elements within the Earth's crust. In fact, the lithosphere is only 0.032% carbon by weight. In comparison, oxygen and silicon respectively make up 45.2% and 29.4% of the Earth's surface rocks.

Carbon is stored on our planet in the following major sinks

  1. As organic  living and dead organisms found in the biosphere;
  2. As the gas carbon dioxde in the atmosphere
  3. As organic matter in soils  
  4. In the lithiosphere as fossil fuels and sedimentary rock deposits such as limestone, dolomite  and chalk
  5. In the oceans as dissolved atmospheric carbon dioxide and as shells in marine organisms.




Carbon dioxide enters the waters of the ocean by simple diffusion. Once dissolved in seawater, the carbon dioxide can remain as is or can be converted into carbonate (CO3-2) or bicarbonate (HCO3-). Certain forms of sea life biologically fix bicarbonate with calcium (Ca+2) to produce calcium carbonate(CaCO3). This substance is used to produce shells and other body parts by organisms such as coral, clams, oysters, some protozoa, and some algae. When these organisms die, their shells and body parts sink to the ocean floor where they accumulate as carbonate-rich deposits. After long periods of time, these deposits are physically and chemically altered into sedimentary rocks. Ocean deposits are by far the biggest sink of carbon on the planet.



Sangeetha Pulapaka
0
Hi RAB, did you want to include a subtext for this question?