, 1996, Majchrowski, 2001 and Woźniak and Dera, 2007). The relationship between the number of quanta and the energy of the light absorbed by phytoplankton pigments is given by the so-called quantum equivalent of light energy X, which is equal to the ratio of the number of quanta absorbed to the sum of their energies. By taking this equivalent X into account, we can calculate the energy efficiencies of fluorescence Rfl and ATM/ATR phosphorylation rfl on the basis of the corresponding quantum yields of this process Φfl and qfl, using the equations given in Table 1 (lines 1, 2). For these calculations, we take the value of X that we calculated for the

light absorbed by all phytoplankton pigments 1. using the equations from the earlier comprehensive light-photosynthesis model ( Woźniak et al. 2003). The vertical distributions of X in sea waters of different trophic types and at different depths

in the upper water layers, of thicknesses from 1 to 2 times the depth of the euphotic zone, are given in Figure 2. From the characteristics of the variability of X it becomes clear that the energy efficiencies of chlorophyll Epigenetics inhibitor a fluorescence (Rfl and rfl) are usually somewhat lower than the quantum yields of this process (Φfl and qfl), especially in oligotrophic, mesotrophic and weakly eutrophic basins. Again, the energy efficiencies of photosynthesis (Rph and rph) are usually some four times smaller than the corresponding quantum yields of the process (Φph and qph). This is because a minimum of eight quanta from all the light quanta absorbed by PSP molecules (together with the chlorophyll a molecules at the photosynthetic reaction centres) are required to close off the cycle of endoenergetic chemical

reactions in photosynthesis leading to the assimilation of one atom of carbon, even though not BCKDHA all of the energy of these eight quanta is utilized in these reactions ( Govindjee, 1975 and Najafpour, 2012). The energy equivalent of organic carbon kep contained in various organic substances may fluctuate within quite wide limits, depending on the type of substance involved. For substances photosynthesized by phytoplankton this equivalent kep ≈ 40 kJ g− 1 ( Koblentz Mischke et al. 1985). This calculation shows that for one atom of carbon to be assimilated, that is, for it to be bound in an organic form, the energy contained in two quanta of light from the visible spectrum is more than sufficient. The resulting relationships between the energy efficiencies (Rph and rph) and quantum yields (Φph and qph) of the photosynthesis of phytoplankton in the sea are given in Table 1, lines 2 and 4. Likewise, the efficiencies of the conversion of pigment molecule excitation energy into heat (in the radiationless and nonphotochemical dissipation of this energy) RH and rH differ from the quantum yields of these processes ΦH and qH.