Geochemical investigations on fluvial sediments contaminated by tin-mine tailings, Cornwall, England.

Abstract

Tin-mine tailings containing high levels of Sn, Cu, Zn, Fe, Mn, As, and W are discharged into the Red River and then transported into St Ives Bay. Most of the Sn-bearing particles in the fluvial sediments are <170 mu m in size, Sn distribution being controlled by i) distance from the source of the tailings, and ii) concentration processes operating on the river bed. Suspended and saltation-transported sediments filtered from river water samples also showed high metal levels, these lying within narrow ranges in contrast to the bottom sediments. Distributions of Cu, Zn, Fe, As, and Pb in the filtered sediments are probably governed by the behaviour of their sulphides during transportation. A regional stream-sediment geochemical reconnaissance survey indicated that tin re-concentration by selective removal of light minerals had taken place in the bottom sediments after mining operations had ceased.D.J.M.