Incorporation of metalliferous sediments from historic mining into river floodplains

Rivers and their floodplains are dynamic systems, sediments are continually added to floodplain surfaces, while erosion and scour may remove sediments to be added to floodplains further downstream. When mining sediments were introduced into some catchments in Britain as ore deposits were exploited, river channels and floodplains were grossly polluted with metals. The legacy of this uncontrolled release of contaminants is apparent still, and contemporary channel deposits are enriched in metals. While the floodplains acted as a buffer to the dispersal of metals straight through the catchment, metals are still being released hundreds of years later as the floodplains are eroded and this secondary pollution of the river is a long-term problem.By studying a range of mining catchments, the effects of key variables on heavy metal dispersal in the fluvial environment can be assessed. As no single catchment displays the whole array of possible situations, a mosaic of case studies from several areas provides a good representation of potential conditions.