Metal contamination in Weardale stream sediments, Northern Pennine Orefield, UK

A total of 107 samples of active stream sediment were collected at 1km intervals over the drainage network of Upper Weardale. In this area of Northern England the River Wear traverses the Northern Pennine Orefield, in which Pb-Zn-F-Ba vein mineralization has been exploited historically by hydraulic, surface and underground mining. Whereas previous regional geochemical surveys avoided potential sources of anthropogenic contamination and sampled minor tributaries, the present survey was of active sediment in the main channel of the River Wear and the major tributaries. Analysis for a range of metals has revealed widespread contamination which persists downstream. Comparisons to sediment quality guidelines indicate that significant levels of As are present in addition to the anticipated concentrations of Pb and associated metals usually present in the ore and gangue mineral assemblage.