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Browsing Publications by Department "1Inproyen Consulting SL"
  • Publication
    Calidad ambiental de suelos y aguas de la Mina Fé: Situación inicial y alternativas de recuperación
    (Universia, 2020-03-15)
    ARAN FERREIRO, DIEGO
    ;
    Verde J.R.
    ;
    Antelo J.
    ;
    Macías F.
    Mining activity leads to several environmental impacts. After the closure, the realization of a holistic evaluation of the main ecosystem components and their environmental risks is essential in order to define and manage a sustainable rehabilitation program specific to the current environmental situation. The objective of this work was to evaluate the chemical quality of the soils and runoff waters of the uranium mine, Fé mine (Saelices el Chico, Spain), in order to establish a diagnosis of the existing environmental problems and potential recovery actions to apply. Soils located within the mining area and natural soils from adjacent areas were sampled, classified according to the World Reference Base and analysed for their physico-chemical properties. Moreover, runoff water samples were collected for chemical and thermodynamic evaluation as well as, in the dry period, salt efflorescences from surface materials for chemical and mineralogical analysis. The natural soils (classified as Lithic, Haplic and Skeletic Leptosols, Leptic and Haplic Cambisols, Plinthic Acrisols, and Haplic and Gleyic Fluvisols) have low fertility (evaluated by concentration of nutrients and organic matter) and a strong erosive tendency which, together with the climatic conditions of the area, lead to a poor vegetation cover development. These soils are very incipient and are only located in areas where there is a permanent vegetation cover. Most of the mine soils are developed on different mixtures of host rock and sulfide-rich wastes, being classified as Sulfidic or Salic Spolic Technosols, depending on their specific properties and/or conditions. These mixtures of materials diminish the negative effect of the mine wastes, since the total concentrations of potentially toxic elements are similar (except for Pb) between mine and natural soils. However, these mine soils present a high environmental risk due to the generation of leachates with hyper-acid (pH ≈ 2.8), hyper-oxidant (Eh ≈ 759 mV) and hyper-conductor (EC ≈ 12.8 dS m-1) characteristics and with potentially high toxic elements (e.g. Al, Fe and Mn) and sulfates (22.9-33.9 g L-1). In the dry period, the ascension of the soil solution rich in elements contributes to the formation of evaporitic salts on the materials which were mainly identified as Al and Mg sulfates (epsomite and halotrichite). These solid phases are only temporary sinks of sulfate and metals, since they are re-dissolved with rain, releasing the elements to the environment. Moreover, the low fertility and cation exchange capacity, high acidity, stoniness and salinity of the mine soils limit the natural colonization and vegetative development. Considering the environmental risk and characteristics/conditions of the mine soils, the recovery process of the Fé mine should focus, mainly, on the sulfide oxidation minimization and fertility improvement in order to promote the establishment of a biodiverse plant cover as well as pedogenetic and biogeochemical processes.