Hydrochemical variations and contaminant load in the Rio Tinto (Spain) during flood events

Canovas, C. R., Hubbard, C. G., Olias, M., Nieto, J. M., Black, S. ORCID: https://orcid.org/0000-0003-1396-4821 and Coleman, M. L. (2008) Hydrochemical variations and contaminant load in the Rio Tinto (Spain) during flood events. Journal of Hydrology, 350 (1-2). pp. 25-40. ISSN 0022-1694 doi: 10.1016/j.jhydrol.2007.11.022

Abstract/Summary

The aim of this work is to study the hydrochemical variations during flood events in the Rio Tinto, SW Spain. Three separate rainfall/flood events were monitored in October 2004 following the dry season. In general, concentrations markedly increased following the first event (Fe from 99 to 1130 mg/L; Q(max) = 0.78 m(3)/s) while dissolved loads peaked in the second event (Fe = 7.5 kg/s, Cu = 0.83 kg/s, Zn = 0.82 kg/s; Q(max) = 77 m(3)/s) and discharge in the third event (Q(max) = 127 m(3)/s). This pattern reflects a progressive depletion of metals and sulphate stored in the dry summer as soluble evaporitic salt minerals and concentrated pore fluids, with dilution by freshwater becoming increasingly dominant as the month progressed. Variations in relative concentrations were attributed to oxyhydroxysulphate Fe precipitation, to relative changes in the sources of acid mine drainage (e.g. salt minerals, mine tunnels, spoil heaps etc.) and to differences in the rainfall distributions along the catchment. The contaminant load carried by the river during October 2004 was enormous, totalling some 770 t of Fe, 420 t of Al, 100 t of Cu, 100 t of Zn and 71 t of Mn. This represents the largest recorded example of this flush-out process in an acid mine drainage setting. Approximately 1000 times more water and 1408 200 times more dissolved elements were carried by the river during October 2004 than during the dry, low-flow conditions of September 2004, highlighting the key role of flood Events in the annual pollutant transport budget of semi-arid and and systems and the need to monitor these events in detail in order to accurately quantify pollutant transport. (c) 2007 Elsevier B.V. All rights reserved.

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Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/3346
Item Type	Article
Divisions	Science > School of Archaeology, Geography and Environmental Science > Department of Archaeology Science > School of Archaeology, Geography and Environmental Science > Scientific Archaeology
Uncontrolled Keywords	AMD Rio Tinto metal load flood events ACID-MINE DRAINAGE IBERIAN PYRITE BELT TRACE-METAL ENRICHMENTS SOUTH-WEST SPAIN SOUTHWESTERN SPAIN SULFATE MINERALS ESTUARINE SYSTEM IRON-MOUNTAIN SW SPAIN RIVER
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