f-ratio

In oceanic biogeochemistry, the f-ratio is the fraction of total primary production fuelled by nitrate (as opposed to that fuelled by other nitrogen compounds such as ammonium). This fraction is significant because it is assumed to be directly related to the sinking (export) flux of organic marine snow from the surface ocean by the biological pump. The ratio was originally defined by Richard Eppley and Bruce Peterson in one of the first papers estimating global oceanic production.