Productivity Modeling Analysis
The Algenol Productivity Model (Legere, 2017; Chance and Roessler, 2019) is used to analyze these indoor PBR experiment results, and determine if a set of photosynthetic parameters can be developed to adequately represent all experimental results. A representative model parameter set for the productivity model is derived from the PE data sets with [\(\alpha\), Ek, R0] = [0.061 fixed C/photon, 240 µE m-2 s-1, 0.1 µmol C mgChl.a-1 min-1] at 30 °C providing a reasonable representation of the entire data base. The R0 value at the reference 30 °C temperature was taken as 0.1 µmol C mgChl.a-1 min-1consistent with conclusions from outdoor experiments on a carbon basis (Legere 2017; Chance and Roessler, 2019) and recognizing that R0’ determinations from PE curves will show an irradiance-related enhancement (Falkowski and Raven, 2007). To model temperature effects, Ek is set as a function of temperature (activation energy 60 kJ mol-1 ), and the respiration rate (R0) was modeled as a function of temperature (activation energy as 27 kJ mol-1), with the activation energy estimates being consistent with previous studies (Legere, 2017). Table 4 gives a summary of the model parameter values. Comparison between the modeled and experimental productivities are shown in Figure 7. The model results are in good in agreement with experiment results for all cases considered here. Even at 35 °C, where clear changes in pigmentation are seen, the agreement is satisfactory. For example, with temperature increased from 20 °C to 30 °C, the biomass productivity increases by 28% (experimental) and 26% (productivity model). At higher light intensities >>Ek, an increase of 100%, or Q10 = 2, would be expected. Good agreement between biomass productivities for the small, L scale, experiments reported here and the large, 24000 L scale, outdoor experiments (Chance and Roessler 2019) was noted earlier. This consistency can be extended to the PE experiments (mL scale) where the derived photosynthetic parameters are in good agreement with those employed for model representations of large scale outdoor experiments (Chance and Roessler, 2019; Supplementary Material).