Rio Tinto estuary (Spain): 5000 years of pollution

Mining of massive sulfide deposits in southwestern Spain extending back to the Copper and Bronze Ages has resulted in the pollution of the Rio Tinto f luvial-estuarine complex, the site of Colombus' departure for the New World in 1492. Additional sources of potential pollution include the large indus trial complex at Huelva near the lower portion of the estuary. Extensive an alysis of surface sediment samples and cores has established that there are no geographic trends in the distribution of the pollutants, which include Cu, Fe, Pb, Zn, Ti, Ba, Cr, V and Co. These data have, however, demonstrate d that tidal flux within the estuary carries phosphorus and perhaps other e lements from the industrial complex at Huelva to the tidal limit of the sys tem, several kilometers upstream from the discharge site. Radiometric analy sis of short cores shows that sedimentation rates over at least the past co uple of centuries have been about 0.3 cm/year. These data and that from a s ingle deep core demonstrate that the estuary was polluted from mining activ ity long before the large-scale operations began in the late nineteenth cen tury.