%0 Journal Article
%T Growth of Photosynthetic Biofilms and Fe, Pb, Cu, and Zn Speciation in Unsaturated Columns with Calcareous Mine Tailings from Arid Zones
%A J. V. Garc¨Şa-Meza
%A M. I. Contreras-Aganza
%A J. Castro-Larragoitia
%A R. H. Lara
%J Applied and Environmental Soil Science
%D 2011
%I Hindawi Publishing Corporation
%R 10.1155/2011/732984
%X Mine tailing remediation aims to reduce the rate of sulfide mineral oxidation. Earlier studies showed that photosynthetic biofilms may act as a physical barrier against oxygen diffusion. Currently, a long-term assay (6 months) is required to evaluate the solid phase redistribution of the Pb, Fe, Cu, and Zn originally present in historic and calcareous mine tailing samples (in our case from a semiarid region in North-Central Mexico). The presence of biofilms may provide chemical gradients and physical conditions that shift the proportion of Fe, Cu, and Zn originally associated with oxides to carbonates and organic matter/sulfide fractions. 1. Introduction The oxidation and dissolution of sulfide minerals (SMs) present in mine tailings (vr. gr. pyrite (FeS2), arsenopyrite (FeAsS), galena (PbS), sphalerite (ZnS), chalcopyrite (CuFeS2)) can produce acidic metal-rich waters known as acid mine drainage (AMD) within tailing deposits and at the receptors (soil and water sediments). Mine tailing remediation aims to reduce the rate of SM oxidation by avoiding or reducing contact between the SM and the oxidant agents such as atmospheric or dissolved oxygen (O2) or ferric ions (Fe(III)). It has been proposed that water coverage could be used to reduce O2 diffusion into tailing dams [1¨C3]. Other types of covering such as multilayer covers have also been proposed, and this consists of a profile of well structured layers (surface, drainage, moisture, retaining, and support layers) with different hydrogeological properties. Ideally, the surface layer must support vegetation and retain moisture. Bussi¨¨re et al. [2] indicated that multiple covers with capillary barrier effects are useful for low-sulfide tailing from a wet or temperate climate region. However, designing efficient covers with different capillary barrier effects can be difficult because of variable climatic conditions and layer geometry as well as the complex behavior of unsaturated materials [4]. Furthermore, the multilayer cover might need considerable quantities of covering material. If sufficient cover material is not available in the vicinity of the tailing impoundments, then the material needs to be removed and transported to the site resulting in a significant increase in cost and the alteration of other environments. Therefore, the barrier of choice depends mainly on climate, geology, mineralogy, and economic factors. For abandoned mine tailing dams, the former is of special concern as no mining company assumes any responsibility for the remediation action. Garc¨Şa-Meza [5] showed that photosynthetic
%U http://www.hindawi.com/journals/aess/2011/732984/