Redfield ratio

The Redfield ratio or Redfield stoichiometry is the consistent atomic ratio of carbon, nitrogen and phosphorus found in marine phytoplankton and throughout the deep oceans.

The term is named for American oceanographer Alfred C. Redfield who in 1934 first described the relatively consistent ratio of nutrients in marine biomass samples collected across several voyages on board the research vessel Atlantis, and empirically found the ratio to be C:N:P = 106:16:1. While deviations from the canonical 106:16:1 ratio have been found depending on phytoplankton species and the study area, the Redfield ratio has remained an important reference to oceanographers studying nutrient limitation. More recent work looking at data accumilated since the 1970s reported the global median C:N:P to be 163:22:1; however, the ratio between these element is not only more varied in the ocean, it has also been changing through time.