What is the largest and the second-largest carbon sinks? not including the atmosphere?

Oceans and soils

Explanation:

Carbon sink is a natural carbon reservoir which is responsible for the absorption and storage of the carbon containing chemical compounds by using physical and biological mechanisms. This process is also known as carbon sequestration, as it involves the removal of carbon dioxide from the Earth's atmosphere.

Currently, Oceans are the largest carbon sinks on Earth, followed by soils.