A possible source of error in the 14C method of measuring primary productivity: Limnology and Oceanography

A relationship, not due to self-absorption, has been shown between volume filtered and apparent specific activity of plankton, in which the latter decreases with increasing volume filtered. This decrease is attributed to an increased damage to phytoplankton during vacuum filtration as the volume filtered and consequently the filtration time were increased, Carbon fixation rates calculated from uptake of 14C were lower than rates determined by the On method (gross fixation) unless they were corrected for loss of “C during filtration. The corrected values were similar to those obtained by the Or method