Papers by Keyword: Iberian Pyrite Belt

Abstract: Cueva de la Mora and Guadiana are two acidic mine pit lake in the Iberian Pyrite Belt (south-west Spain) that exhibit depth-related stratification, which is in turn reflected in the bacterial community population the different layers. Here we describe the microbial communities present in samples of sediments located close to the surface and deep within the lakes, which show interesting contrasts to planktonic communities.

Abstract: Abstract. In mining areas in which sulfur-containing ores are exposed, the oxidation of sulfides leads to the formation of acidic mine drainage (AMD) waters. Both traditional and molecular microbial studies have shown that chemolithotrophic sulfur- and iron-oxidizing bacteria are responsible for this activity. The Iberian Pyrite Belt (IPB), located in southwestern Spain represents one of the world’s largest accumulations of mine wastes and AMD waters. Mineralogical and textural characteristics of the IPB ores favor the oxidation and dissolution of pyrite and the subsequent formation of AMD waters. Acidic pit lakes in the IPB are a hotspot for this activity. These pit lakes are former open pit mines where ores have been exposed leading the formation of AMD waters. At present, there are more than 25 of these pit lakes between the provinces of Huelva and Seville (SW Spain). This work reports the physical properties, hydrogeochemical characteristics, and microbial diversity of two pit lakes located in the IPB Nuestra Señora del Carmen (NSC), and Concepción (CN). Both pit lakes are acid (pH 2-4) and showed chemical and thermal stratification with well defined chemoclines. One particular characteristic of NSC is that it has developed a chemocline very close to the surface (2 m depth). Microbial community composition of the water column was analyzed by 16S and 18S rRNA gene cloning and sequencing. The microorganisms detected in NSC are characteristic of acid mine drainage (AMD), including iron oxidizing bacteria (Leptospirillum) and facultative iron reducing bacteria and archaea (Acidithiobacillus ferrooxidans, Actinobacteria, Acidimicrobiales, Ferroplasma) detected in the bottom layer. Diversity in CN was higher than in NSC. Microorganisms known from AMD systems (Acidiphilium, Acidobacteria and Ferrovum) and microorganisms never reported from AMD systems were both identified.

Abstract: The microbiology and geochemistry of two pit lakes at former metal mines (Cueva de la Mora and Guadiana) located in the Iberian Pyrite Belt in Spain were investigated. Both lakes are meromictic, with more acidic and oxidized mixolimnion zones overlying anoxic monimolimnion zones, and transitional chemoclines with characteristic sharp pH and redox potential gradients. Stratification in the pit lakes was reflected in the size and diversity of the microbial communities in the different zones, with the chemocline of Cueva de la Mora pit lake and the hypolimnion (the lower layer of the mixolimnion) in the Guadiana pit lake containing the most complex and abundant microbial communities. Acidophiles that oxidize and reduce both iron and sulfur co-exist within the chemocline/hypolimnion zones, implying that biogeochemical cycling of these two elements is most intense within these layers of the pit lakes. Novel species of bacteria were detected using molecular techniques and, in some cases, isolated and partially characterized. The latter included a novel acidophilic iron-reducing gammaproteobacterium (Acidibacter ferrireducens)

Abstract: A 1.2 km long effluent from La Zarza-Perrunal mine (Iberian Pyritic Belt, IPB) was characterized and compared with Río Tinto. In La Zarza effluent microbial oxidation of ferrous iron is responsible for the drastic increase in ferric iron, from a ratio of Fe(III)/Fetotal of 0.11 at the origin, up to 0.99 downstream. Prokaryotic and eukaryotic diversity throughout the effluent were determined. Bacteria related to the sulfur cycle as well as iron-reducing bacteria were mainly detected near the anoxic origin. Iron-oxidizing microorganisms increased along the course of the effluent following an increase in the oxygen content in the water column. Eukaryotic diversity varied drastically along the effluent. Rio Tinto (92 km length) is a natural extreme acidic environment with a rather constant acidic pH (mean pH value 2.3) and a high concentration of heavy metals. The Tinto ecosystem is under the control of iron [1]. The geomicrobiological comparisons of both habitats were performed to unravel some basic questions of biohydrometallurgical interest.

Abstract: Rio Tinto (Iberian Pyritic Belt, SW Spain) is a natural extreme acidic environment with a rather constant acidic pH (mean pH value 2.3) and a high concentration of heavy metals. The Tinto ecosystem is under the control of iron. The geomicrobiological characterization of Río Tinto has unravelled some basic questions of biohydrometallurgical interest. The methodologies developed for this study were applied successfully to monitor different bioleaching processes of the BioMinE project.