Identify the two major zones of the ocean
environment

They are,

benthic zone or ocean floor and pelagic zone or ocean waters

Explanation:

The pelagic or ocean waters refers to the zone beyond the continental shelf and it is the zone where organisms swim or float. Organisms live and survive in this zone.

The benthic zone is the deepest part of the ocean and it is beyond the pelagic zones, some organisms live in this zone too but there are sediments or deposits in this zone of the ocean.

the answer is:

carbon dioxide