A comparison of solute concentrations of streams draining different rock types in two areas of upland Britain

To determine how widely applicable were the findings from a long running catchment study in mid Wales, eight upland streams in northern England were sampled. The streams were selected to ensure that their catchments were entirely underlain by one of three rock types which contrasted with the rock types of the Welsh catchments. Water was collected at approximately five week intervals over a period of 16 months. Samples from both areas were analysed for 13 ions, including the major nutrients, using the same laboratory methods. pH and Dissolved Total Organic Carbon were also determined. Concentrations of a number of ions were low compared with more intensively managed land but some seasonal trends were identified. Association between streams, in terms of solute concentration, was examined using Principal Component Analysis. Component values were related to physical characteristics of the catchments and it was concluded that of the physical characteristics examined, rock type had the greatest influence on stream water chemistry. It is recornended therefore that rock chemistry be taken into account when applying the findings from the Welsh study to other catchments.