Resumen de Geoavailability of Ni, Cu, Zn, As, Cd, and Pb in the Sierra de Cartagena- La Unión (SE Spain)
Resumen de la tesis:
The aim of this thesis was to contribute to the interpretation of the geogenic and anthropogenic factors, at local (hydrographic basin) and regional levels, that control the geoavailability (solubility and mobility) of Ni, Cu, Zn, As, Cd, and Pb in the Sierra Minera de Cartagena ¿ La Unión, as well as to evaluate the influence of the abandoned mining landscape on the Campo de Cartagena and Mar Menor lagoon. The study period extended from 2003 to 2012.
Across the large plain of 1600 km2 that forms the Campo de Cartagena, 15 weather stations were monitored to collect 920 rainwater samples. In addition, 179 surface runoff water samples were gathered in 13 ephemeral watercourses, 127 springwater samples in 5 springs, 16 seawater samples in 8 wadi outlets, 15 efflorescent sulfate salts, 7 types of mine wastes, and 23 types of parent materials. The assessment of such variety of specimens helped to understand the mechanisms that make Ni, Cu, Zn, As, Cd, and Pb geoavailable in the Sierra Minera of Cartagena ¿ La Unión. For this purpose, these trace elements were studied in the geological context, taking into account their geochemical cycles, the different types of mining and metallurgical wastes present in the derelict mining site, and the sphere of influence to the bordering areas.
The results have confirmed that geoavailability of trace metals in the Sierra Minera is governed by physico-chemical weathering of mining and metallurgical wastes, as well as by the oxidation of metallic sulfides associated to the Pb-Zn ores. Regarding the transport, dispersion, and deposition mechanisms of Ni, Cu, Zn, As, Cd, and Pb, the geoavailable trace-metal mass balance for Mar Menor lagoon disclosed that aeolian erosion transfered 81% of the overall input of metal pollutants coming from the Sierra Minera, groundwater input contributed 16%, and watershed stream input only represented 3%. This proved that scattering of those trace elements is NOT controlled by continental water bodies (surface runoff and groundwater).
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