Seasonal variation of metal contamination of riverine sediments below a copper and sulphur mine in South-East Ireland

The discharge of acid mine drainage (AMD) from the abandoned sulphur and copper mines at Avoca (S.E. Ireland) results in the formation of ochreous deposits on the river substrate. Sediment sampling was carried out intensively during June and August, 1994 and again during March and April, 1995 to investigate seasonal variation of Fe, Cu and Zn concentration in riverine sediments of the receiving water (Avoca River). Temporal and spatial variations indicate that, apart from pH, hydrological factors play a major role in metal accumulation of highly energetic river systems. Zinc adsorption and desorption of “ochre” is chiefly regulated by pH, while Cu removal seems to be primarily by co-precipitation with iron. Basic considerations with regard to sampling techniques are discussed.