how does carbon enter the hydrosphere
Lithosphere; carbon in the lithosphere is held in soil in the form of both organic and inorganic carbon (often as calcium carbonate). Carbon can leave the soil through soil respiration â which releases CO2, or by erosion â which can carry it into rivers or the ocean, where it then enters the hydrosphere. Within the Earthâs crust a large amount of carbon is stored in limestone and kerogens (the term given to organic matter held within sedimentary rocks).