Dissolved silicon in a North Wales catchment of high relief

Abstract

Concentrations of dissolved silicon and nitrogen in the Afon Anafon, a river draining the mountainous region of North Wales, were monitored over an annual cycle. As a result of the high relief the silicon concentration in the baseflow was diluted by surface flow and interflow. This led to low silicon concentrations in the river water (maximum 1540 μg l−1, minimum < 100 μg l−1) an inverse relationship between silicon concentration and discharge and a low removal rate of silicon by dissolution from the catchment (0.07 mg SiO2 cm−2 yr−1). Nitrate concentrations, in contrast, showed a typical seasonal variation and were less affected by variations in the discharge.