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Published April 1997 | public
Journal Article

A 120 yr record of widespread contamination from mining of the Iberian pyrite belt

Abstract

A metal-enriched seawater plume entering the western Mediterranean Sea through the Strait of Gibraltar originates 300 km to the west in the Rio Tinto estuary of southwestern Spain. Mining of Rio Tinto ore, one of the largest metal-rich sulfide deposits in the world, started well before Roman times. Contemporary Rio Tinto waters draining the region are highly acidic (pH 2.5) with dissolved cadmium, zinc, and copper concentrations 10^5–10^6 times higher than in uncontaminated surface water of the Gulf of Cadiz. Two dated sediment cores from the Spanish continental shelf show that metal inputs to the region increased with the onset of intensive mining activities during the second half of the 19th century. Although the impact of mining may have decreased over the past few decades, the Tinto river and estuary remain highly contaminated.

Additional Information

© 1997 Geological Society of America. Manuscript received September 11, 1996; Revised manuscript received January 8, 1997; Manuscript accepted January 22, 1997. We thank J. M. Martin for facilitating surface water collection off the Portuguese coast and S. N. Luoma and M. Bacon for use of their laboratories. National Science Foundation Summer Fellow A. Schmid extended the metal contamination record to Roman times. Sample collection in the Rio Tinto-Odiel was funded by the Office of Naval Research. Collection of sediment cores from the Gulf of Cadiz was funded by the Joint Committee of Science and Technology of the United States–Spain Treaty of Friendship. Lamont-Doherty Earth Observatory contribution no. 5620.

Additional details

Created:
August 22, 2023
Modified:
October 18, 2023