This is one of the biogeochemical cycles; it has both a sedimentary and gaseous phase, enters biological cycles through photosynthesis, and is the largest contributor to acid rain and smog.

The answer is; Carbon Cycle

Carbon exists in the atmosphere as carbon dioxide. It is incorporated into the biosphere through photosynthesis where it is converted to carbohydrates. When carbon-based compounds are burned in air, carbon dioxide is produced and when it moves with precipitation, it causes acid rain (carbonic acid).