Ammonium inhibition of nitrate uptake by phytoplankton: A new relation based on similarity and hyperbolicity

Abstract

A theoretical formulation based on the properties of similarity and hyperbolicity is given for ammonium inhibition of nitrate uptake by phytoplankton. It leads to a new kinetic relation for ammonium inhibition, which is found to represent the data of nitrogen kinetics experiments of McCarthy et al. in the northwest Indian Ocean more accurately than the earlier relations of Wroblewski and O'Neill et al. Analysis of the ƒ-ratio (new production/the sum of new and regenerated production) implied by the three relations shows that there is a qualitative difference among the three. The relation of Wroblewski tends to underestimate the new production, while that of O'Neill et al. tends to overestimate it.