At the surface, there is a balance between destruction
(output) and production (input) of these gases. For example,
nitrogen is removed from the atmosphere primarily by bio-
logical processes that involve soil bacteria. In addition, nitro-
gen is taken from the air by tiny ocean-dwelling plankton that
convert it into nutrients that help fortify the ocean’s food
chain. It is returned to the atmosphere mainly through the
decaying of plant and animal matter.