This resource from the Hawaii Ocean Time-Series provides a protocol used to determine primary productivity by 14C assimilation. It includes a brief overview of the method as well as the equation used to determine how much carbon is fixed.
This resource is referenced here: Subject
Water Column, Biology,
Biology:Microbiology:Methods of Microbiology :
: Graduate/Professional, College Upper (15-16)
Biosphere:Methods of Microbiology:
Teach the Earth:Course Topics:
phytolankton, GPP, NPP, gross primary productivity, net primary productivity, DIC, dissolved inorganic carbon