The calculation of base cation release from mineral weathering in soils derived from Palaeozoic greywackes and shales in upland UK

Weathering rates for soil profiles and catchments developed on greywacke and shale parent materials have been calculated using four common methods cited in the literature (conservative element depletion, the PROFILE model, catchment input-output mass balance (budgets) and the MAGIC model). A comparison of the results suggests that for any single method the results are consistent. However, comparison between methods suggests a greater variation and systematic difference between weathering rates calculated from soil profiles compared to those calculated on a catchment basis. The reason for these differences and the implications for acidification and critical load work are discussed.