THE S DOMINGOS MINE - A STUDY OF HEAVY-METAL CONTAMINATION IN THE WATER COLUMN AND SEDIMENTS OF THE CHANCA RIVER BASIN BY DISCHARGE FROM AN ANCIENT CUPRIFEROUS PYRITE MINE (PORTUGAL)

The water column and the sediment in the S. Domingos Mine area and the associated drainage stream are heavily contaminated by heavy metals. The Chanca Reservoir, into which this stream flows, shows a localized area where the sediment is contaminated by heavy metals, but in general the water column does not show any contamination. Both water column and sediment quality were analysed, including determination of total heavy metal concentration as well as acid volatile sulfide (AVS) and simultaneously extracted metal (SEM). The ratio between SEM and AVS is less then 1 for almost all sampling sites, showing that the Chanca Reservoir appears to be protected in most areas with respect to both sediment and water column toxity.