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Metal geochemistry in a mine-polluted estuarine system in Spain

Metal geochemistry in a mine-polluted estuarine system in Spain
Metal geochemistry in a mine-polluted estuarine system in Spain
The Rio Tinto and Rio Odiel drain the Iberian Pyrite Belt, an important metal-rich sulphide deposit. The rivers are highly acidic (pH 2.2–3.6) and have milli-molar SO4 and Fe concentrations and micro-molar Co, Cu, Mn and Zn concentrations. Observed dissolved metal levels were at a maximum during autumn and early winter surveys (e.g. Rio Tinto: 460–856 ? M Cu), and lower in late winter, spring and summer (121–175 ? M Cu). This variability is attributed to the production of concentrated acid mine drainage (AMD) during periods of enhanced microbial activity at higher temperatures in summer, and a subsequent run-off of the AMD into the rivers with the first rain in the autumn. Lower temperatures and dilution by winter floods resulted in a reduction of river metal concentration towards the end of the wet season. Metal distributions in the estuarine mixing zones of the Tinto and Odiel were governed by the acidity. The lack of metal transfer from the dissolved to the particulate phase in the low salinity region is attributed to the electrostatic repulsion between the metal cations and positive charges on particle surfaces, and/or to the protonation of adsorption sites at low pH. Dissolved Pb was an exception and showed marked removal in the low salinity zone at low pH (pH 2.5), due to its particle reactive nature. The gross metal fluxes from the Rio Tinto and Rio Odiel are important on a global scale, for example amounting to 8.1 and 1.6% of the estimated global riverine dissolved Zn and Cu fluxes. The fluxes of metals from the estuary contribute to enhanced dissolved metal concentrations observed in the Gulf of Cadiz.
0883-2927
1757-1771
Braungardt, C.
14dc28af-5c64-4b58-bf4a-53edd21e9456
Achterberg, E.P.
685ce961-8c45-4503-9f03-50f6561202b9
Elbaz-Poulichet, F.
89e521c6-779a-4e5e-b169-554f402d879e
Morley, N.H.
76957d0d-b0be-4220-8149-240d9030dac2
Braungardt, C.
14dc28af-5c64-4b58-bf4a-53edd21e9456
Achterberg, E.P.
685ce961-8c45-4503-9f03-50f6561202b9
Elbaz-Poulichet, F.
89e521c6-779a-4e5e-b169-554f402d879e
Morley, N.H.
76957d0d-b0be-4220-8149-240d9030dac2

Braungardt, C., Achterberg, E.P., Elbaz-Poulichet, F. and Morley, N.H. (2003) Metal geochemistry in a mine-polluted estuarine system in Spain. Applied Geochemistry, 18 (11), 1757-1771. (doi:10.1016/S0883-2927(03)00079-9).

Record type: Article

Abstract

The Rio Tinto and Rio Odiel drain the Iberian Pyrite Belt, an important metal-rich sulphide deposit. The rivers are highly acidic (pH 2.2–3.6) and have milli-molar SO4 and Fe concentrations and micro-molar Co, Cu, Mn and Zn concentrations. Observed dissolved metal levels were at a maximum during autumn and early winter surveys (e.g. Rio Tinto: 460–856 ? M Cu), and lower in late winter, spring and summer (121–175 ? M Cu). This variability is attributed to the production of concentrated acid mine drainage (AMD) during periods of enhanced microbial activity at higher temperatures in summer, and a subsequent run-off of the AMD into the rivers with the first rain in the autumn. Lower temperatures and dilution by winter floods resulted in a reduction of river metal concentration towards the end of the wet season. Metal distributions in the estuarine mixing zones of the Tinto and Odiel were governed by the acidity. The lack of metal transfer from the dissolved to the particulate phase in the low salinity region is attributed to the electrostatic repulsion between the metal cations and positive charges on particle surfaces, and/or to the protonation of adsorption sites at low pH. Dissolved Pb was an exception and showed marked removal in the low salinity zone at low pH (pH 2.5), due to its particle reactive nature. The gross metal fluxes from the Rio Tinto and Rio Odiel are important on a global scale, for example amounting to 8.1 and 1.6% of the estimated global riverine dissolved Zn and Cu fluxes. The fluxes of metals from the estuary contribute to enhanced dissolved metal concentrations observed in the Gulf of Cadiz.

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Published date: 2003

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Local EPrints ID: 1344
URI: http://eprints.soton.ac.uk/id/eprint/1344
ISSN: 0883-2927
PURE UUID: 2f5fb2c7-fb6b-4717-a570-ee7d14b4ab0b

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Date deposited: 16 Apr 2004
Last modified: 15 Mar 2024 04:43

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Contributors

Author: C. Braungardt
Author: E.P. Achterberg
Author: F. Elbaz-Poulichet
Author: N.H. Morley

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