Chemical analysis is an essential step to establish the nature of minerals (Newman, 1987). The techniques used in rock and mineral analyses are generally valid for the analyses of clays. Additional information from other analytical techniques, which are mentioned here, is needed for accurate interpretation of the chemical analysis results of major elements (Gabis, 1979). In traditional chemical analyses, the aim is to obtain accurate analyses for all elements present in the sample, in such a way that the sum of elements expressed as oxides, including hydration and structural water, approaches the sample weight as closely as possible.

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Amendments with organic and industrial wastes stimulate soil formation in mine tailings as revealed by micromorphology Zanuzzi, A.; Arocena, J.M.; van Mourik, J.M.; Faz Cano, A. General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Mine tailings are inhospitable to plants and soil organisms, because of low pH and poor soil organic matter contents. Vegetation establishment requires a soil system capable of supporting the nutrient and water requirements of plants and associated organisms. The objective of this study was to understand the influence of added organic and industrial wastes to the formation of soils in degraded landscapes left behind by past mining activities. Specifically, we stimulated the build up of soil organic matter (SOM) and the accumulation of calcite in mine tailing deposits. We amended field experimental plots with pig manure (PM), sewage sludge (SS) in combination with blanket application of marble wastes (MW). Soil samples were collected for physical and chemical analyses, two years after the addition of industrial wastes. Three years after amendments, we took undisturbed samples for micromorphological analysis. Soil pH increased from 2.7 to 7.4 due to dissolution of calcite from MW amendment. The acidity in tailings and low rainfall in the study area precipitated the secondary calcite as infillings within the 0-4 cm layer. Total organic carbon (TOC) increased from 0.86 to 2.5 g TOC kg − 1 soil after 24 months since the application of amendments. The build up of SOM resulted to stable SOM-calcite complex as dense incomplete infillings mixed with secondary calcite, and cappings on calcite particles from MW addition. These SOM cappings provide water and nutrient to support initial seedling establishment in mine tailings. We attribute the granular structure of amended materials to soil organisms (e.g., earthworm activity) involved in the decomposition of plant materials. We suggest that any organic matter amendments to acidic mine tailing deposits must be combined with calcium carbonate-rich materials to accelerate the build up of SOM to accelerate the establishment of functional ecosystem characterized by, among others, the presence of healthy soils with granular microstructure.

Mine tailing ponds are environmental hazards because of high susceptibility to leaching and erosion by water and wind. Vegetation establishment is an effective technique to reclaim tailing ponds but requires knowledge of the spatial relationship between the structural composition and physical and chemical properties of soils. In this study we have demonstrated the use of electrical resistivity imaging (ERI), combined with soil chemical analyses, to determine the structural and chemical composition of mine tailing ponds to assess efficient measures of environmental protection. We used a Syscal R1 resistivity meter to generate twoand three-dimensional (2-D/3-D) ERI images from El Lirio and Brunita mine tailing ponds. Soil samples were collected at 1-m intervals to a depth of 15 m, and were analyzed for pH, electrical conductivity and cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn) contents. Results show that materials in the ponds can be classified into three categories: fine tailings -low ER (,8 Vm), coarse waste rock -intermediate ER (8-150 V-m), and bedrock -high ER (.150 V-m). Our interpretation of the 2-D/3-D ERI images with respect to the historical depositions of materials in the ponds show that at El Lirio, decant water outlet was initially at the center and advanced to the east of the tailing pond as the mining activities progressed. At Brunita, the intermediate ER values on the west side of the pond marked the deposition of coarse waste rock materials released during a pond breakage in 1972. The ERI helped us image the spatial distribution of tailings and its qualitative spatial correlation with chemical properties (i.e., pH, EC, metals content). Low ER values are related to high amounts of Zn, Pb, Cu and Cd. These qualitative relationships underlie the usefulness of the combined geophysical and soil chemical approaches to improve our understanding of the properties of mine tailing ponds in the Sierra Minera (and other parts of the world).