56
The Radiocarbon Method to Estimate Primary Production
a
b
H,m
e
d
Fig. 2.15. Typical depth-photosynthesis curve Ks in a
stratified basin in summer to be used for calculation of
integrated primary production Cp" for legend see text
tions (Kt Kp). The form of the K t curves is determined by the water transparency and therefore has a rather universal character (Rhode 1958; Vollenweider 1974; Fig. 2.14). Being estimated several times experimentally in a given
water body during a given season, a selection of the Kl curves thus obtained
can be used for Ks calculations at numerous other stations, by correcting the
actual extension of the euphotic zone and the surface illumination. The extension of the euphotic zone can be estimated with the aid of a submersible photometer or a Secchi disk. In the latter case, the depth of the euphotic zone will
be approximately equal to 3.3 Secchi disk transparency depths, which corresponds to 1-3% of PARS.
The Kp curves should be estimated at each station or, at least, at stations,
which differ significantly from each other in vertical profiles of chlorophyll or
in temperature profiles as indicators of stratification. In any case, Cps must be
measured at each station. At stations where Kp curves were not estimated, for
Ks calculations Kp curves can be adopted measured at neighboring stations
with similar indices of stratification. Estimations of Kp are performed by measuring relative photosynthesis rates in a series of samples taken at the stations
on the vertical profile and incubated in the deck aquarium under equal temperate illumination. Therefore the use of this method avoids in situ incubation
at each station to measure Cpt-values.
The light curves Kl can be obtained practically in several ways. One is the
experimental estimation of these curves in the basin under investigation at
several selected stations which characterize its range of water transparency. It
is also very important to estimate K t curves on bright and dull days. As an
example from our practice, during a 4-month oceanographic cruise, to determine the integrated primary production at each of the 100-150 stations
studied, the necessary light curves K t were measured at some three to five stations during the whole cruise (Sorokin 1971; 1973c). To construct the K t curve,
the corresponding K t coefficients are first estimated by experimental mea-
The Radiocarbon Method to Estimate Primary Production
a
b
H,m
e
d
Fig. 2.15. Typical depth-photosynthesis curve Ks in a
stratified basin in summer to be used for calculation of
integrated primary production Cp" for legend see text
tions (Kt Kp). The form of the K t curves is determined by the water transparency and therefore has a rather universal character (Rhode 1958; Vollenweider 1974; Fig. 2.14). Being estimated several times experimentally in a given
water body during a given season, a selection of the Kl curves thus obtained
can be used for Ks calculations at numerous other stations, by correcting the
actual extension of the euphotic zone and the surface illumination. The extension of the euphotic zone can be estimated with the aid of a submersible photometer or a Secchi disk. In the latter case, the depth of the euphotic zone will
be approximately equal to 3.3 Secchi disk transparency depths, which corresponds to 1-3% of PARS.
The Kp curves should be estimated at each station or, at least, at stations,
which differ significantly from each other in vertical profiles of chlorophyll or
in temperature profiles as indicators of stratification. In any case, Cps must be
measured at each station. At stations where Kp curves were not estimated, for
Ks calculations Kp curves can be adopted measured at neighboring stations
with similar indices of stratification. Estimations of Kp are performed by measuring relative photosynthesis rates in a series of samples taken at the stations
on the vertical profile and incubated in the deck aquarium under equal temperate illumination. Therefore the use of this method avoids in situ incubation
at each station to measure Cpt-values.
The light curves Kl can be obtained practically in several ways. One is the
experimental estimation of these curves in the basin under investigation at
several selected stations which characterize its range of water transparency. It
is also very important to estimate K t curves on bright and dull days. As an
example from our practice, during a 4-month oceanographic cruise, to determine the integrated primary production at each of the 100-150 stations
studied, the necessary light curves K t were measured at some three to five stations during the whole cruise (Sorokin 1971; 1973c). To construct the K t curve,
the corresponding K t coefficients are first estimated by experimental mea-