Red Field Ratio

The Redfield ratio is the consistent atomic ratio of carbon, nitrogen and phosphorous found in marine phytoplankton and throughout the deep oceans (C:N:P = 106:16:1). When nutrients are not limiting, the molar elemental ratio C:N:P in most phytoplankton is 106:16:1

In the ocean, a large portion of the biomass is found to be nitrogen-rich plankton. Many of these plankton are consumed by other plankton biomass which have similar chemical compositions. This results in a similar N:P ratio, on average, for all the plankton throughout the world’s oceans, empirically found to average approximately 16:1. When these organisms sink into the ocean interior, their biomass is consumed by bacteria that, in aerobic conditions, oxidize the organic matter to form dissolved inorganic nutrients, mainly carbon dioxide, nitrate, and phosphate.

That the nitrate to phosphate ratio in the interior of all of the major ocean basins is highly similar is possibly due to the residence times of these elements in the ocean relative to the ocean’s circulation time.