Hydrological conceptual model characterisation of an abandoned mine site in semiarid climate. The Sierra de Cartagena-La Unión (SE Spain)
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Universidad de Barcelona
Materia
Fractured aquifer Open-pit and underground mining Sierra de Cartagena-La Unión Acid mine drainage Semi-arid zone hydrology
Date
2010Referencia bibliográfica
Robles-Arenas, V.M.; Candela, L. Hydrological conceptual model characterisation of an abandoned mine site in semiarid climate. The Sierra de Cartagena-La Unión (SE Spain). Geologica Acta, 8(3): 235-248 (2010). [http://hdl.handle.net/10481/33462]
Sponsorship
The authors would like to thank the Ministry of Science and Innovation (project CGL2007-66861-C04) and the Seneca Foundation of Spain (project PB/44/FS/2002) for the financial support.Abstract
A comprehensive study at Sierra de Cartagena-La Unión (SE Spain) abandoned mine site was carried out to characterise
the regime and water quality of the groundwater system after the mine closure. The system consists of
five geologic fractured blocks belonging to the Alpujarride and Nevado-Filabride complexes. The aquifer units
are composed of limestone and dolostone materials. Recharge is mainly controlled by the N-130 fault system,
man-made induced fractures, open-pits and underground workings. Discharge is indicated from open pit lakes
by the proximal dome-shaped groundwater level contours. Aquifer natural recharge, assessed by fracture density
maps and chloride mass balance, provided consistent results. The water hydrochemical facies show a marked
sulphate concentration and acidic pH (average pH of 2.53-6.30). A maximum concentration of 4,100 mg/L of Zn
and 40,000 mg/L of sulphate was observed in open-pit lakes. Springs present the lowest residence time and are
low mineralised with an average pH of 7.6. Geochemical modelling based on the PHREEQCI code indicates water
undersaturation with respect to almost all related mineral species and anoxic conditions prevail in the system.
Although an adequate understanding of the regional system is provided, a further detailed hydrochemical study is
necessary to assess the undergoing geochemical changes.