Coastal subsystems tend to release CO_2 to the atmosphere simply because of the contrasting elemental stoichiometry (the ratio of carbon to nitrogen, C:N) of terrestrial organic matter (TOM) decomposition and aquatic primary production. TOM carried to the coast by rivers typically has a high C:N (30:1 to 60:1) (Box Fig., left), whereas organic matter produced by algae such as phytoplankton in coastal systems has C:N near 7:1 (Box Fig., right).
展开▼
