What's air, water, and soils role in the carbon cycle

They are reservoirs of carbon in the carbon cycle.

Explanation:

A biogeochemical or nutrient cycle has two major components:

the reservoirs of the biogeochemical or nutrient, and the processes involved in cycling the biogeochemical or nutrient between the reservoirs.

Air is a reservoir of largely inorganic carbon (as carbon dioxide) while water and soils are reservoirs of both organic (e. g. dead decomposing organisms and hydrocarbons) and inorganic forms of carbon (e. g. carbon-containing minerals such as limestone, calcium carbonate).