Gh. Rau et al., A MODEL OF PHOTOSYNTHETIC C-13 FRACTIONATION BY MARINE-PHYTOPLANKTON BASED ON DIFFUSIVE MOLECULAR CO2 UPTAKE, Marine ecology. Progress series, 133(1-3), 1996, pp. 275-285
A predictive model of carbon isotope fractionation (epsilon(p)) and ab
undance (delta(13)C(phyto)) is presented under circumstances where pho
tosynthesis is strictly based on CO2(aq) that passively diffuses into
marine phytoplankton cells. Similar to other recent models, the one pr
esented here is based on a formulation where the expression of intrace
llular enzymatic isotope fractionation relative to that imposed by CO2
(aq) transport is scaled by the ratio of intracellular to external [CO
2(aq)], c(i)/c(e). Unlike previous models, an explicit calculation of
c(i) is made that is dependent on c(e) as well as cell radius, cell gr
owth rate, cell membrane permeability to CO2(aq), temperature, and, to
a limited extent, pH and salinity. This allows direct scaling of c(i)
/c(e) to each of these factors, and thus a direct prediction of epsilo
n(p) and delta(13)C(phyto) responses to changes in each of these varia
bles. These responses are described, and, where possible, compared to
recent experimental and previous modeling results.