Geochemistry, the key to understanding environmental chemistry

Weathering is the most mysterious but also the most mishandled process in soil chemistry modelling. The myth arose that it could never be determined, nor ever modelled. Thus it became the obvious parameter to use for tuning the models, since the real value was unknown. This is not true. New models such as SAFE and PROFILE have made possible modeling of weathering rates in the field from geochemical and geophysical properties. The weathering model in PROFILE is a reductionistic type of model, where the main mechanism is based on a set of parallel molecular mechanisms at the mineral surface. Rate coefficients in the models have been taken from laboratory studies. In field tests, the PROFILE model has performed well and is capable of predicting the weathering rate well within the range determined by other methods. PROFILE is operationally used for regional weathering rate mapping and is currently applied in 37 countries. Through feedback mechanisms in the model, the weathering rate can be used to affect biotic processes.