Publication: The Mazarrón Pb–(Ag)–Zn mining district (SE Spain) as a source of heavy metal
contamination in a semiarid realm: Geochemical data from mine wastes, soils, and
stream sediments
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Publication Date
2011
Authors
Oyarzun, Roberto
Lillo Ramos, F. Javier
Esbrí, J.M.
Cubas, Paloma
Llanos, W.
Higueras, Pablo
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Elsevier Science B.V.
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Abstract
The Mazarrón epithermal ore deposits (SE Spain) formed in Miocene time in relation to the emplacement of
dacitic–rhyodacitic domes. The Pb–(Ag)–Zn ore deposits are of the high sulphidation vein and stockwork
type. There are two main mining sites: San Cristóbal–Perules (adjacent to the town of Mazarrón) and
Pedreras Viejas. The area is located in the southern realm of a Miocene marine basin surrounded by
mountains in its western, eastern and southern flanks. A main seasonal river (Rambla de las Moreras) crosses
the basin from North to South and is strongly affected by contaminated sediments from the San Cristóbal–
Perules mining site. The mine tailings are extremely rich in Pb (mean=12,400 μg g−1) and Zn
(mean=6100 μg g−1), whereas As concentrations are also very high (mean=650 μg g−1). Our geochemical
survey also covered anthropic soils, stream sediments and the so-called almagres deposits (red alum
calcines). All these environmental matrices have also very high concentrations of Pb, Zn, As, and Cd
compared to our local or world baseline concentrations. The calcines are rich in As (mean=450 μg g−1), and
the main environmental concern relates to the wrong use of these materials as agricultural soils at discrete
sites in the district. Besides, the anthropic soils of the district are very rich in Pb (mean=2550 μg g−1) and
Zn (mean=1870 μg g−1). On the other hand, the seasonal river Rambla de las Moreras receives
contaminated sediments from the San Cristóbal–Perules old mining site and mine wastes, which results in
high concentrations of As (mean=120 μg g−1), Pb (mean=2700 μg g−1) and Zn (mean=1090 μg g−1) in
the sediments. These high concentrations of dangerous contaminants in an area close to a town of 35,000
inhabitants and adjacent to significant agricultural activity may pose a risk to human health.