The distribution of the stable isotopes of Cu and Fe in nature is susceptible to isotope fractionation processes during the biogeochemical cycle. Since Cu and Fe are redox sensitive metals, differences in their oxidation states can lead to variations in the stable isotope composition of the aquatic species or compounds that they form. Stable isotopes of Cu and Fe have recently been used to trace metal redox cycles, nutrient pathways, metal contaminant sources and to develop isotopic biosignatures. The objective of this project was to study the geochemical processes governing the isotopic fractionation of Cu and Fe in mine impacted sites, including processes related to mineral processing. One of the key questions was to explain the role of bacteria in the variations of the isotopic composition of Cu and Fe. First, bioleaching and electroleaching of a chalcopyrite concentrate were performed. During the chalcopyrite leaching in both experiments the first release of Cu to the leachate is enriched in the heavier Cu isotope as a product of oxidative dissolution. At the later stages of leaching, the δ65Cu values for the leachate are similar to the initial material, confirming an equilibrium fractionation in a closed system. In the case of Fe isotope fractionation the dissolution of pyrite at redox potentials higher than 600mV leads to an enrichment of the heavier Fe isotope in the leachate in the bioleaching experiment, mainly regulated by the formation of secondary minerals such as jarosite. Soil bacteria were studied in three different experimental scales using pot, lysimeters and field experiments, amended with autochthonous plant growth promoting bacteria. Roots and plants from pots showed no variation in their Fe and Cu isotope composition compared to non-amended samples. However, plants growing in the amended substrates regardless of their experimental scale, showed variations in the Fe and Cu isotope composition of their roots with an increase in the heavier Cu isotope. Siderophores released either by bacteria or the plant can complexate available Cu and Fe in the soil, causing a change in the isotope fractionation of those metals. The second question is related to the biogeochemical cycle of Cu and Fe. In mine tailings the sulphide oxidation resulted in an enrichment of the lighter Cu isotope in secondary phases in the oxidized zone of the tailings compared to the original isotope composition in the unoxidised mineral. Precipitation of covellite at the oxidation front of the tailings profile resulted in a significant enrichment of the lighter Cu isotope in the bulk soil with a δ65Cu value as low as -4.35 ±0.02 ‰. Fe isotope fractionation in the Kristineberg test cell varied due to processes such as Fe(II)-Fe(III) equilibrium and precipitation of Fe-(oxy)hydroxides at the oxidation front, where δ56Fe values were higher than in the initial material. As a way to link the obtained results from this thesis, a self-restored mine site was studied. A variation towards higher δ65Cu values was seen from rocks, to water and biofilms. Cu absorption mainly by extrapolymeric substances and secondary mineral precipitation regulates the isotopic composition of the biofilm. Oxidative weathering of sulphide minerals and further precipitation of Fe-(oxy)hydroxides are considered to be the main causes for Fe isotope fractionation in this area. Summing up, this thesis provides several field studies to corroborate the data observed in the lab regarding processes that are important for the biogeochemical cycling of metals and could be further applied to the extraction of metals or for remediation purposes. / Godkänd; 2013; 20131028 (natper); Dissertation to be held in public in room E632 on Tuesday 17th of December at 10:00 am. External examiner: Dr. Dominik Weiss, Department for Earth Sciences and Engineering, Imperial College London. Chairman: Professor Björn Öhlander, Division of Geosciences and Environmental Engineering, Luleå University of Technology. --- Tillkännagivande disputation 2013-11-22 Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Nathalie Pérez Rodríguez Ämne: Tillämpad geologi/Applied Geology Avhandling: Biotic and Abiotic Isotope Fractionation of Copper and Iron. From the Lab to the Field Scale Opponent: Dr Dominik Weiss, Reader, Department of Earth Science & Engineering, Imperial College of London, UK Ordförande: Professor Björn Öhlander, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Tid: Tisdag den 17 december 2013, kl 10.00 Plats: E632, Luleå tekniska universitet

The notion of mine site reclamation is very recent compared to the history of mining. In thepast, mine sites were left as is following termination of the operations, but modern regulationsrequire anticipation of long-term contamination of the surrounding environment and return ofthe land to a sustainable use. A primary concern for mines used to extract sulphide-rich ores isthe generation of acid mine drainage (AMD), a low-pH and metal-rich solution formed whensulphidic mining wastes and mining surfaces come into contact with oxygen and water. AMDmay be responsible for the contamination of watercourses and other receiving environments fardownstream of the site. Thus, reclamation at such sites will usually involve measures intendedto prevent or mitigate its generation. Despite their relatively recent introduction, the increasingtime that has passed since the first prevention and mitigation programmes were applied at minesites, some two to three decades ago, provides an invaluable opportunity to assess their long-termeffects on the abatement of AMD.Reclamation at the Kimheden copper mine in Västerbotten, northern Sweden, involved theprogressive backfilling of two small open pits with waste rock and application of a dry cover in1996, in order to reduce the influx of atmospheric oxygen into the waste. The objective of thestudies this thesis is based upon, performed in 2009 – 2014, was to evaluate the effects of thesereclamation measures on the abatement of Cu and Zn-rich AMD and to identify potential inadequaciesin them, using geochemical, geophysical and hydrogeological methods.The results show that despite large reductions in Cu and Zn concentrations in the receivingstream following reclamation, its water quality has remained in a steady state for about a decadeand is still not considered satisfactory for discharge into the natural environment. Steady-statemoderately high concentrations in the stream, together with a relatively short turnover time forwater in contact with the waste rock, indicate that sulphide oxidation is continuing in the backfilldespite the cover. Hydrogeochemical modelling suggests that the rate of oxygen consumption bysulphide oxidation in the waste rock is higher than the expected rate of diffusion through the drycover. Substantial ingress of oxygen into the waste was also corroborated by stable isotope measurements and direct measurements of dissolved oxygen concentrations in the groundwater of the backfill. According to sulphate isotope distributions in the mine drainage, oxidation of pyrite by Fe(III) constantly rejuvenated by oxidation of Fe(II) with oxygen is suspected to be an importantprocess in the covered backfill. Potential sources of oxygen transport into the waste have been explored. Mapping of the groundwater table in one of the backfilled open pits showed that up to 40 % of the waste rock is unsaturated during baseflow, providing pathways for oxygen to enter through unsaturated fractures in the pit walls. Two sources of deterioration of the dry cover were identified during geophysical surveys: seepage of drainage water from the backfilled waste upwards into the dry cover and insufficient thickness of the cover in some areas. Geophysical and hydrogeochemical studies showed that the collection ditch constructed to divert the contaminated water to a liming treatment station fails to retain a large fraction of the drainage.Based on the results obtained, the sustainability of current approaches for AMD prevention andmitigation is discussed, and possible strategies for improving backfilling and sealing measures atsimilar sites are proposed.Keywords Acid mine drainage or acid and metalliferous drainage (AMD) or acid rock drainage(ARD); mine site reclamation; open pit; sulphidic waste rock; backfilling; dry cover; performance;unsaturated. / Godkänd; 2014; 20141016 (lucvyl); Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Lucile Villain Ämne: Tillämpad geologi/Applied Geology Avhandling: Reclamation of Acid-Generating Waste Rock by In-Pit Backfilling and Sealing - An Evaulation of the Kimheden Mine Site, Northern Sweden Opponent: Professor Bernhard Dold, University of Chile, Santiago, Chile Ordförande: Professor Lena Alakangas, Avd för geovetenskap och miljöteknik, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Tid: Fredag den 12 december 2014, kl 10.00 Plats: E632, Luleå tekniska universitet

No description available.

<p>Godkänd; 1994; 20080401 (ysko)</p>

A field filtration method for the concentration and separation of suspended particulate matter (SPM) from freshwater systems and the subsequent determination of major, minor, trace and ultra trace elements (Al, As, Ba, Be, Ca, Cd, Co, Cr, Cs, Cu, Fe, Ga, Hf, K, Mg, Mn, Mo, Na, Nb, Ni, P, Pb, Rb, S, Sb, Sc, Si, Sn, Sr, Ta, Th, Ti, Tl, U, V, W, Zn and Zr) is validated with respect to detection limits, precision, and bias. The validation comprises the whole procedure including filtration, sample digestion and instrumental analysis. The method includes two digestion procedures (microwave acid digestion and alkali fusion) in combination with inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma quadrupole mass spectrometry (ICP-QMS). Total concentrations of these 38 trace and major elements have been determined in suspended particulate matter (SPM) from lake and river water with low levels of suspended solids (<2 mg l-1 DW), and a wide range of element concentrations. The precision of the method including filtration, digestion and instrumental determination ranges between 8 and 18% RSD for most elements on a dry weight basis. Higher recovery after acid digestion is found for some elements, probably because of volatilization or retention losses in the fusion procedure. Other elements show higher recovery after fusion, which is explained by more efficient decomposition of mineral phases relative to the non-total acid digestion. Non-detectable concentrations of some elements are reported due to small differences between blank filter levels and the amounts of elements present on the filters after sampling. The calculated sums of main inorganic components, expressed as oxides, ranges between 94.0 and 98.0% ash weight. The method limits of detection range between 0.7 ng and 100 µg, as estimated from the blank filter samples. These detection limits are 3-1000 times higher compared to the corresponding instrumental limits of detection. The accuracy and bias of the overall analytical procedure was assessed from replicate analysis of certified reference materials. A better knowledge of the mechanisms of filter clogging in sampling of suspended matter is important in order to extend the applicability of the method. For the sample types investigated in this study, the amount of inorganic material in the suspended particulate matter (SPM) seems to be the most important factor controlling the maximum volume of filterable water, and Fe is presumable the most important clogging regulating parameter in the group of elements included in the inorganic matter. A critical evaluation of the instrumental capabilities of the ICP- QMS instrumentation in comparison with the sensitive double focusing sector field plasma mass spectrometry technique (ICP-SFMS) is also included. It was found that a modified microwave acid digestion procedure in combination with ICP-SFMS could replace ICP-AES determinations and fusion digestions for most of the investigated elements. Guidelines and limitations for this powerful and relatively simple and less time consuming procedure, covering most elements in one single determination, are discussed. / Godkänd; 2004; 20070126 (ysko)

The Aitik mine, near Gällivare in Sweden, is the largest copper mine in Europe with an annual production exceeding 18 Mt of ore. After processing of the ore the residual waste material, so called tailings, are deposited in a tailings pond. In addition, 15 - 25 Mt of barren waste rock is mined annually in order to provide access to the ore. The waste rock is deposited in waste rock dumps located close to the mine. The production started 1968, and very large quantities of waste have been accumulated since. A comprehensive set of strategies for management and decommissioning of the waste deposits have been developed, based on studies, investigations and tests carried out by Boliden, as well as independent consultants and universities, since the first permit regulating reclamation issues came into force 1989. During operation of the mine, the emissions to the receiving environment are limited. During a normal year, the effluent contains less than 50 kg of copper. However the internal circulation of copper is orders of magnitude larger. This fact calls for suitable decommissioning measures to prevent an increase of the emissions after closure. Moreover, by developing and implementing strict waste management routines the potential environmental impacts can be minimized and closure costs drastically reduced. As a foundation for the test work a variety of site investigations were carried out to establish the hydrogeological and geochemical conditions. Material characterization results show that some but not all waste types and categories may cause acid rock drainage (ARD). In order to reach conclusive results extensive kinetic test periods, using column and humidity cell tests, were required in combination with geochemical modelling to provide reliable results. Results of long term weathering and leaching tests on mill tailings were compared with measured weathering rates in field. The results show that weathering in field is much slower than in lab, but that there is still a potential for generation of acid leachate in the upper section of the tailings storage facility after closure. An alternative strategy was therefore developed, in which the iron sulphides will be removed from the bulk volume of the tailings during the last years of operation. The tailings depleted of sulphides would hence constitute a cover on the underlying tailings, with water saturation of the untreated tailings with higher sulphide content. The enriched sulphide product needs to be deposited separately during the last years and decommissioned using other methods, e.g. engineered cover or water cover. This can be obtained either in a selected part of the existing tailings pond where water saturation can be guaranteed, or by depositing the high sulphide tailings in the bottom of the open pit which will fill up with water after closure. Various reclamation methods for the waste rock deposits have been evaluated. Tests show that only a fraction of the tonnage is reactive, in average 20% without taking into account mixing due to practical reasons, which will increase the tonnage of contaminated rock. Therefore, procedures for selective management and deposition have been introduced for each rock type present. Existing dumps of mixed rock, when completed, will be covered with 2*0,5 m of compacted till and a topsoil of till with a content of sewage sludge or similar additive as vegetation layer. The oxygen inflow is thereby limited to 1% of the case before covering. Old dumps containing marginal ore, which were found to be the main sources of metals at the site, have been removed and processed and hence eliminated as sources of contaminant release. Large quantities of non-reactive waste rock are managed in a separate mass flow, constituting a large future source for aggregates production for construction purpose. The Aitik decommissioning project constitutes an example of how scientific methods applied to real life problems can lead to reduced potential environmental impacts, reduced liabilities, reduced closure costs as well as improved resources use - all in line with the sustainable development philosophy. / Godkänd; 2005; 20061214 (haneit)

Investigations concerning naturally occurring, mass dependent isotope fractionation of transition elements in biological materials have only been carried out during a very short period of time. Due to the lack of detailed descriptions of the analytical performance in previously reported work, the major focus of this study has therefore been to evaluate aspects of sample preparation and detection for obtaining precise and accurate isotopic ratios by multi-collector inductively coupled plasma mass spectrometry (MC- ICP-MS) using high mass-resolution. Quantitative determinations of elemental concentrations were performed by sector field ICP-MS using external calibration and internal standardization. Dissolution of whole blood and soft tissue reference materials in a micro-wave oven, or on a hot plate, using HNO3 resulted in concentrations of Zn, Fe and a host of other elements in agreement with certified values. This, together with high chemical yields of Zn and Fe (>93%) from the sample purification by anion- exchange chromatography or precipitation by NH3, limited the possibility for laboratory-induced isotope fractionation. Concentrations of the majority of potentially interfering elements were reduced to negligible levels, and most of the residual spectral interferences were resolved using medium (in the case of Zn) or high (Fe) mass-resolution settings of the MC-ICP-MS-instrument. To correct for differences in instrumental mass discrimination effects between samples and isotopic standards, concentrations were matched to within 10-20%, and Cu and Ni were employed as elemental spikes, for measurements of Zn and Fe, respectively. Almost all samples and standards were analysed in duplicate (or triplicate), and exponential correction for instrumental mass discrimination was performed by applying the exponential model. Precision at the sub-‰ level was achieved for both Zn and Fe delta-values, relative to a JMC Zn standard and an IRMM-014 Fe isotopic reference material, respectively. For the investigated reference materials, delta66/64Zn ranged from 0.07 ± 0.03‰ in human hair to 0.50 ± 0.03‰ in bovine muscle. Concerning Fe, a delta56/54Fe-value of -2.83 ± 0.06‰ was obtained for a human whole blood reference material. Variations in delta66/64Zn values, ranging from +0.56‰ in human whole blood to -0.60‰ in human hair were found, demonstrating fractionation of the Zn pool between body compartments. Where comparable isotopic determinations exist, the results were in good agreement. / Godkänd; 2004; 20070127 (ysko)

<p>Godkänd; 1998; 20070404 (ysko)</p>

Two abandoned pit lakes in northern Sweden were studied in order to improve the understanding of the geochemistry of pit lakes, Rävlidmyran Pit Lake and Udden Pit Lake. Both lakes show strong similarity with other mining lakes in terms of low pH and high metal and sulphate contents. Still, the two lakes have distinctly limnological and geochemical characteristics. Rävlidmyran Pit Lake is oligotrophic and meromictic. The lake is permanently stratified and three layers, the mixolimnion at the top, the chemocline below and the monimolimnion further below, are identifiable. Groundwater filling and stratification strongly control the elemental distributions in the lake. Most elements such as Ca, Mg, Na, K, S, Mn, Fe and Zn have lowest and constant concentration in the mixolimnion. Concentrations increase in the chemocline and keep rising in the monimolimnion. These elements show quite similar behaviour in the water with strong correlations. Groundwater is supposed to be the major source. Fe is removed from the mixolimnion due to oxidation and precipitation, but it is redissolved in the monimolimnion. Udden Pit Lake is a dimictic lake. Distinct overturning in spring and autumn occurs in the lake, during which the whole lake circulates and most of the parameters and chemical components become homogeneously distributed. The lake is thermally stratified in summer and winter. Three layers, the epilimnion at the top, the metalimnion below and the hypolimnion at depth could be identified. The thermal strata do not control the elemental distribution. During stratification, the concentrations of dissolved elements appear to be constant at most depths. Variations mainly occur in the top and bottom waters. Most elements such as Ca, Mg, Na, K, S, Mn, Cu Al and Zn have lowest concentration in the epilimnion. Concentrations increase in the metalimnion and kept constant in the hypolimnion. Fe concentration distribution reflects the changes of redox potential. High amounts of Fe2+ reaching the surface water by drainage waters from closely situated waste rock dumps cause higher dissolved Fe concentration and lower redox potential in the top water. Precipitation of dissolved Fe into suspended Fe occurs in deeper water where the redox potential is higher. In both lakes, a strong relationship between Cu and Al is found. Gibbsite is important since it controls both dissolved Al and Cu concentrations in the lake through processes of adsorption and precipitation. Otherwise scavenging processes by particles are not a significant factor controlling trace metal distributions due to the low suspended particle concentration in both lakes. Sulphate reduction was neither observed in Rävlidmyran nor in Udden, even though the oxygen concentration is poor in the deep waters. The high redox potential limits the formation of sulphides, thus precluding an important precipitation of trace metals as metal sulphides. / Godkänd; 2002; 20070222 (ysko)

Godkänd; 1999; 20070403 (ysko)