PH SIMULATION-MODEL IN A MIXED-LAYER OF A LACUSTRINE ENVIRONMENT (THECASE OF LAKE ORTA)

Some important basic aspects of pH simulation using a comprehensive on e-dimensional (vertical) diffusive model (ORTAMOD) are presented. In p articular, considerations are made on the validation of the two critic al parameters: net alkalinity (ALNE), which represents the balance bet ween net alkalinity and mineral acidity related to external input and internal processes; and total carbon concentration (C-T) considering t he carbon related to respiration/photosynthesis processes and calculat ed from the stoichiometric Redfield elemental ratio (C:H:N:O:P). The m odel calculates the pH with an algorithm applicable to different water bodies: rain waters, lake waters at different altitudes and hydrochem ical characteristics, and river waters, proving itself to be a useful tool for understanding the theory of these analytical data. The simula tion results using ORTAMOD show the usefulness of combining measuremen ts in the field with predictive equilibrium models in order to underst and the phenomena and mechanisms governing the equilibrium ecosystem. The choice of ALNE and C-T as the individual parameters in the pH eval uation seems appropriate, but some difficulties in the correct modelli zation of the real field partial pressure of CO2 values still emerge.