The application of Sr isotopes to catchment studies: The Plynlimon upland catchment of Central Wales

摘要

The determination of specific flowpaths and the formulation of process-oriented models for upland catchment systems has proved difficult. This is largely due to the heterogeneous nature of catchments and the necessary limitations of bulked parameter models. Strontium isotopes were used as a natural tracer to calculate weathering rates and help determine flowpaths in two upland forested sub-catchments of the River Severn (Afon Hafren and Afon Hore) at Plynlimon in Central Wales. Weathering rates in the Afon Hafren catchment for Sr and Ca calculated using Sr isotopes were similar to those derived from mass balance studies, except for Sr in the Afon Hore which differed significantly. The reasons for this are not yet clear. Strontium isotope ratios for different input sources and compartments within the catchment show large variations and help to identify potential flowpaths. The role of groundwater in streamflow generation is considered important during both baseflow and stormflow.