What is the primary environmental abiotic carbon source for the carbon cycle?

Carbon cycles throughout the planet in different forms and reservoirs. They are found underground as fossils, as living and dead organic matter, marine sediments, and atmospheric carbon dioxide. Biotic sources are forests and the dead organic matter ultimately fossilized after millions of years, while abiotic sources come from the environment or non-living things.

The primary abiotic carbon source is the carbon dioxide in the air, which is emitted through fossil fuel combustion, respiration, and decomposition.