pH simulation model in a mixed layer of a lacustrine environment (the case of Lake Orta)

Some important basic aspects of pH simulation using a comprehensive one-dimensional (vertical) diffusive model (ORTAMOD) are presented. In particular, considerations are made on the validation of the two critical parameters: net alkalinity (ALNE), which represents the balance between net alkalinity and mineral acidity related to external input and internal processes; and total carbon concentration (CT) considering the carbon related to respiration/photosynthesis processes and calculated from the stoichiometric Redfield elemental ratio (C:H:N:O:P). The model calculates the pH with an algorithm applicable to different water bodies: rain waters, lake waters at different altitudes and hydrochemical characteristics, and river waters, proving itself to be a useful tool for understanding the theory of these analytical data. The simulation results using ORTAMOD show the usefulness of combining measurements in the field with predictive equilibrium models in order to understand the phenomena and mechanisms governing the equilibrium ecosystem. The choice of ALNE and CT as the individual parameters in the pH evaluation seems appropriate, but some difficulties in the correct modellization of the real field partial pressure of CO2 values still emerge.