Carbon (C) is a chemical element that, when burned with oxygen (O 2), combines to make carbon dioxide (CO 2). It is found in all organic materials whether alive or dead. Carbon is released as CO 2 when we burn fossil fuels such as coal, oil and gas. It is also produced when animals and plants use oxygen to release energy from food or when they die. Most of our atmosphere is made up of nitrogen (78 per cent by volume) and oxygen (21 per cent by volume).
http://www.forestry.gov.uk/forestry/infd-7m8fa6
Some estimates say it's even more than half! However, phytoplankton are not the only source of oxygen. Phytoplankton produce oxygen through photosynthesis. Photosynthesis is the process that plants use to produce their own food. During photosynthesis plants use the energy from the sun to convert carbon dioxide from the air into sugar molecules. When they do this they consume water and also carbon dioxide, and they produce oxygen.
http://scienceline.ucsb.edu/getkey.php?key=359
Like many other sources of carbon, charcoal can be used for the production of various syngas compositions; i.e., various CO + H 2 + CO 2 + N 2 mixtures. The syngas is typically used as fuel, including automotive propulsion, or as a chemical feedstock.
https://en.wikipedia.org/wiki/Charcoal
Movie: carbon sequestration. Trees use energy from sunlight to convert CO2 from the air into sugars. This is the process of photosynthesis. These sugars fuel tree growth and wood production. When trees die most of the stored carbon is returned to the atmosphere, although some of it may be locked up in the soil.
http://www.forestry.gov.uk/forestry/infd-7m8fa6
Carbon Moves between Sources and Sinks. One important aspect of the carbon cycle is the speed with which carbon moves from a carbon source to a carbon sink and then back again. Some living things grow and decompose more quickly than others.
http://teeic.indianaffairs.gov/er/carbon/carboninfo/cycle/
Activated charcoal is available without a prescription, so it is used for a variety of health-related applications. For example, it is often used to reduce discomfort (and embarrassment) due to excessive gas (commonly known as a fart or flatulence) in the digestive tract.
https://en.wikipedia.org/wiki/Charcoal
Charcoal was also used historically as a source of carbon black by grinding it up. In this form charcoal was important to early chemists and was a constituent of formulas for mixtures such as black powder.
https://en.wikipedia.org/wiki/Charcoal
During photosynthesis (photo = light, synthesis = to make), energy from sunlight is captured with special light-absorbing chemicals (called pigments) and this captured energy is used to make living tissue from the carbon molecules in carbon dioxide gas. Oxygen is released almost as a waste product.
http://scienceline.ucsb.edu/getkey.php?key=359
Historically, production of wood charcoal in locations where there is an abundance of wood dates back to a very ancient period, and generally consists of piling billets of wood on their ends so as to form a conical pile, openings being left at the bottom to admit air, with a central shaft to serve as a flue.
https://en.wikipedia.org/wiki/Charcoal
Charcoal is usually produced by slow pyrolysis, the heating of wood or other substances in the absence of oxygen (see char and biochar).
https://en.wikipedia.org/wiki/Charcoal
what is source of the carbon used in making a tree
Carbon dioxide is used in making a tree. Carbon dioxide gas is the source of the carbon used in making a tree.