Toward process-based modeling of geochemical soil formation across diverse landforms: A new mathematical framework

We present a mathematical model that integrates geochemical and geomorphic processes responsible for soils' elemental and mineralogical evolution on diverse landforms: eroding to depositional to level grounds. This new model combines a hillslope sediment mass balance and a soil geochemical mass balance. We model soils as the sum of a physically disturbed zone (PDZ) and the underlying physically undisturbed but chemically altered zone (CAZ). The model considers processes including the production of PDZ, weathering front propagation, mineral-specific dissolution, colloidal translocation, and colluvial transport. Thus this study serves to (1) review preexisting models of pedogenic processes and to (2) offer a framework to integrate the geochemical and geomorphic processes active in soils. We further discuss the implications of our model in (1) scaling chemical weathering reactions from mineral grains to pedons to soil catenas, (2) understanding the emergence of geochemical soil catenas, and (3) coupling physical and chemical weathering processes.