Terrestrial CO₂ Impacts

QPAC has been used to model the ecosystem impacts of naturally occurring surface fluxes of CO2, with a view to providing information on the potential impacts of CO2 geological storage systems.

For example, a study has been made of the Latera site in Italy, working in collaboration with the University of Rome. CO2 migration pathways are restricted at depth to relatively narrow near-vertical channels probably associated with the intersections of faults, above which are heterogeneous layers of alluvium and various volcanic products causing multiple vents associated with each major channel. This was modelled with the QPAC multi-phase flow module, with hydraulic conductivity values varying stochastically, and coupled to a state-of-the-art soil-plant model for the non-linear transport of carbon between different parts of the system. In particular, CO2 in the canopy atmosphere is available for uptake by plants (in this case grass and clover) and incorporation in tissues through photosynthesis.  The net effect of photosynthesis and respiration is represented in terms of plant growth.

The QPAC calculations for the pattern of CO2 venting, and the pattern of crop damage around individual vents, was broadly consistent with field observations at the site and could possibly provide an early warning of CO2 fluxes at a CO2 storage site.