Exchange rates of O₂ and CO₂ between an algal culture and atmosphere

The mechanism of CO₂ and O₂ exchange between atmosphere and an algal mini-pond was examined by monitoring, with a novel microcomputer based system, pH, dissolved oxygen, turbidity, light intensity and temperature. The microcomputer based system was also used to monitor on-line the net oxygen production rate (OPR) and the gas exchange processes. The measured data support the assumption that the gas exchange is driven by the gradient of the partial pressure of the gases across the imaginary boundary layer (z layer). An analytical model based on this assumption was simulated by a computer and compared with the experimental data. The photosynthetic activity of a blue-green alga (Spirulina platensis) mini-pond as it is influenced by the CO₂ concentration in the growth medium is discussed. The overall photosynthetic process was studied by comparing the experimental data with a mathematical model, evaluating the effectiveness of alternative carbon sources.