A thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy in Science to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, 1985 / This volume contains a record of research carried out over the past two decades into problems associated with civil engineering and mining construction materials. Although the various parts of the work were initiated as a result of problems that arose in the Witwatersrand region, the results of the research have in many cases evoked intense interest from other parts of the world. For example, the work on soluble salts in road bases has been taken up in Saudi Arabia and other desert regions, while that on the stability of waste rock dumps has been adopted as a basis for rock dump design in the United States of America. The research revolves entirely about materials, usually, waste, either produced by the mines and reused or disposed of by civil engineers; or reused to provide support by the mines · themselves. The main aim and end result of the research has been a more effective and efficient use of materials and better protection and control of the local environment. / Andrew Chakane 2021

The South African coal industry produces a large quantity of coal per annum. The rejects from various unit operations, such as spirals, consist of fine coal that joins the plants tailings dam waste. As existing high quality resources become depleted, the need to improve recovery of this fine coal grows. This project investigates the use of a teetered bed separator (TBS); a hindered settling gravity concentration device for fine coal recovery. This device has proven successful in the United Kingdom and in Australian collieries for fine coal separation in the size range between 2mm and 0.3mm. It has also been used for decades as a classifying device for silica sand and tin. The TBS operates in the size range of water-only cyclones and spiral concentrators, and could potentially be used to separate a broader size range of coal fines so as to offer a lower footprint device for the fines recovery section of a plant. Spiral concentrators cannot always be operated efficiently at a separating specific gravity of lower than 1.6; a TBS may also extend the density range for separation and thus improve recovery. The objective of this project was to gain a full understanding of the TBS from fundamental particle interaction and develop a lab scale unit, which is capable of separation to about 0.1mm at optimum conditions. This involved the development of design parameters based on the various distributor plates and flow pattern modelling. The hydrodynamics of the separator were investigated using the Eulerian-Eulerian modelling approach of commercial CFD package, Fluent 6.1. Seven distributor plates of varying aperture size and geometric arrangement were considered. Coal and shale particles, sized between 2mm and 0.038mm with a specific gravity (SG) range of 1.2 to 2.0, were separated using the laboratory scale unit. The results of both the simulations and the laboratory tests were then compared. The simulations revealed that Plate 3 was the best option for implementation. It had an even upward velocity profile compared to the other plates, with minimum wall effects and disturbances. The upward water flow rate (teeter water) was varied experimentally and the composition of the teeter bed, underflow and overflow were analysed using 1.5, 2 and Smm cubic density tracers with an SG range of 1.2-2.0. Analysis of the partition curves of the distributor plates revealed that Plate 3 had the lowest Ecart Probable (Ep) and cut- point densities. The comparison of simulated results and experimental results show that the simulator could predict the distributor plate design with the lowest Ep in practical tests. The simulator could be beneficial when optimising an industrial scale unit, by allowing prediction of improved segregation patterns and thus separation efficiency. / Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2005.

Doctor of Philosophy / Department of Agronomy / DeAnn R. Presley / The abandoned lead (Pb) and zinc (Zn) mines in the Tri-State Mining District of Kansas, Missouri, and Oklahoma have left a legacy of environmental contamination. The waste materials are highly polluted, not only with Pb and Zn, but also cadmium (Cd), which often co-occurs geologically with Zn. The District includes Galena, Kansas, where mines operated between 1876 and 1970. Because limited information exists concerning these mines, three studies were done to characterize them and to investigate a way to remediate the mine waste materials. In the first study, the physical characteristics of the mine waste materials were determined. Plots at Galena that had been established by researchers in May 2006 were sampled in November 2014, 8.5 years after they had received amendments (combinations of compost, lime, and bentonite). Water content, bulk density, infiltration rate, unsaturated hydraulic conductivity, aggregate stability, and particle size distribution were determined. The physical characteristics were highly variable, and the amendments added 8.5 years earlier had no effect on them, except the wind erodible fraction (fraction <0.84 mm in diameter) which was low on treatments that contained bentonite. Because biosolids had never been applied to the mine waste materials at Galena for remediation, an experiment was done to see their effect on plant growth and availability of heavy metals. In 2014 the plots established in 2006 were sampled and a greenhouse study was set up with sudex [Sorghum bicolor (L.) Moench x S. Sudanese (P.) Staph]. Plants grew in the mine waste materials with and without biosolids, and 110-111 days after planting the roots, shoots, and heads with grain were harvested and analyzed for heavy metals. At the same time, the mine waste materials were analyzed for heavy metals, organic carbon (C), nitrogen (N), and phosphorus (P). Plants grew better with biosolids than without biosolids, and only the plants grown with biosolids produced heads . Plants grown without biosolids were stunted and showed severe heavy metal toxicity. Organic C and P were increased in the mine waste materials after the addition of biosolids. Thus, the biosolids increased organic C and P, and they apparently made the heavy metals less available for plant uptake. Many studies have shown the importance of attic dust in documenting metal pollution from a mine. Attic dust in Galena had never been studied, so in a third experiment, 14 dust samples in Galena were collected from interiors (attics and one basement) of nine different buildings using two methods: sweeping with a brush and vacuuming. Dust samples were analyzed for heavy metals (Cd, Cu, Fe, Mn, Ni, Pb, and Zn), mineralogy using X-ray diffraction (XRD), scanning electron microscopy (SEM) in conjunction with energy dispersive spectroscopy (EDX), and particle size. Concentrations of Cu, Fe, Mn, Ni, and Zn in the dust were higher than in the mine waste materials. The results from XRD agreed with those from the SEM-EDX analysis. About 10% of each dust sample contained particulate matter (PM) with a diameter of less than 10 μm (PM₁₀), which is a health concern.

One of the main risks that exposed and unvegetated tailings pose to the environment and human health is airborne dust that may be inhaled or ingested. In the case of Pb-bearing dust, both particle size and the identity of the Pb-hosting minerals affect the degree of risk. Finer dusts (<5µm diameter) have a higher potential of being ingested deeper into the human lung causing possible tissue damage and toxic effects. We have collected size-fractionated airborne dust and near-surface pH-neutral tailings at New Calumet Mine, Quebec, Canada, a former Pb-Zn mine. Bioaccessibility describes how much of a substance can be dissolved by body fluids and become available for absorption by the body. The most bioaccessible Pb compounds are PbCO3 (cerussite), Pb3(CO3)2(OH)2 (hydrocerussite) and PbO, followed by PbSO4 (anglesite), PbS (galena) and Pb5(PO4)3Cl (pyromorphite). Airborne dust samples were collected on the tailings piles using a PIXE Cascade Impactor which separates aerosol fractions onto nine impactor stages ranging from 16µm to 0.06µm. These stages were then analyzed by PIXE to obtain elemental concentrations. Samples of non-vegetated and vegetated near-surface tailings were collected for bioaccessibility tests as well as for total metal content, grain size distribution, and Pb speciation using ESEM and synchrotron techniques. Both airborne dust and near-surface tailings samples underwent synchrotron microanalysis including microXRD for identification of microcrystalline compounds and microXRF for element mapping and metal ratio evaluation. Despite extensive oxidation of iron sulfide minerals in the near-surface tailings, galena persists as the most abundant Pb-bearing phase in the pH-neutral tailings. However, rims of cerussite and hydrocerussite forming alteration rims on galena grains have been identified throughout the tailings. In vitro bioaccessibility testing of Pb in the tailings resulted in 0-0.05% bioaccessible Pb in lung fluid and 23-69% bioaccessible Pb in the gastric fluid. / Thesis (Master, Geological Sciences & Geological Engineering) -- Queen's University, 2012-02-28 21:09:08.432

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 90-96). Also available via the Internet.

Low-grade coal, a poor source of energy, has long been regarded as waste material by the coal mining industry. Biological degradation of this coal material by ligninolytic fungal strains presents a viable strategy towards eliminating this unusable fossil fuel. To this end, a novel and patented bioprocess termed Fungcoal was developed. Fungcoal is a biological process utilised in the in situ treatment of waste coal and is based on the mutualistic relationship between the fungus Neosartorya fischeri and the graminaceous species Cynodon dactylon. The process facilitates the rapid conversion of waste coal into soil-like material that stimulates establishment of vegetation for eventual coal dump rehabilitation. While a number of in vitro studies have identified various fungal strains as efficient coal degraders, the mechanisms involved in the Fungcoal-stimulated degradation process have not been fully elucidated. Furthermore, implementation of Fungcoal at both pilot and commercial scale has not been achieved. Thus the objective of this work was to investigate Fungcoal as a bioprocess via examining the role of coal degrading fungi (CDF) and grasses as biocatalysts in coal biodegradation and for the self-cladding of waste coal dumps. Initially, waste coal degradation by N. fischeri, strain ECCN 84, was investigated, specifically focusing on the mechanisms underpinning the process. In vitro studies showed the addition of waste coal induced active fungal colonisation resulting in increased fungal biomass. Increased extracellular laccase (LAC) activity, occuring concomitantly with an increase in hyphal peroxisome proliferation, was also observed in the coal supplied fungal cultures. Analysis of the colonised waste coal revealed a time dependent reduction in the percentage weight of elemental carbon coupled with an increase in elemental oxygen. The results supported metabolism and degradation of waste coal by N. fischeri strain ECCN 84 and involvement of fungal extracellular laccase. The contribution of C. dactylon, a C4 grass species to in situ biodegradation of waste coal in the presence of coal degrading and mycorrhizal fungi (MF) was also investigated. Enhanced degradation of the waste coal into a humic soil-like material was observed within the rhizosphere. Analysis of the resultant substrate revealed an increased concentration of highly oxidised humic-like substances (HS). Fungi remained viable in the rhizosphere up to 47 weeks post-inoculation and cultivation of C. dactylon, indicating the resultant humic substance-rich rhizosphere provided an environment conducive for microbial proliferation and activity. Furthermore, humic substance enrichment of waste coal substrates supported germination and seedling emergence of several agronomic species including Zea mays (corn), Phaseolus vulgaris (bean), Pisum sativum (pea), and Spinacia oleracea (spinach). Use of various cladding materials to support coal biodegradation, by fungus-grass mutualism and rehabilitation of waste dumps was evaluated at commercial scale. While substantial physico-chemical changes were not evident in the absence of cladding or where waste coal was used as cladding material, successful establishment of grass cover and diversity was achieved within three hydrological cycles on dumps cladded with weathered coal. Work presented in this thesis successfully demonstrates the degradation of waste coal by N. fischeri. The biodegradation process included enhanced extracellular LAC activity coupled with increased 3 waste coal oxidation. Increased HS concentration of waste coal substrate supported germination and early seedling establishment of several agronomic species. At commercial scale a co-substrate in the form of carbon-rich weathered coal was essential to support fungus-grass mutualism and Fungcoal-induced rehabilitation. These findings support the developed Fungcoal concept and the underpinning rationale that the phyto-biodegradation of waste coal indeed depends on the mutualistic interactions between grass root exudates and the ligninolytic and mycorrhizal fungi. Taken together, these findings provide practical evidence of the contribution of fungi and grasses as mutualists in the biodegradation of waste coal and sustainable rehabilitation of waste coal dumps

Time-dependent behavior of natural and excavated slopes in sedimentary rocks is a subject that is poorly understood at present but that is now an important consideration in the design, operation, and reclamation of energy-extraction facilities, in part because of the environmental considerations mandated by the Surface Mining Control and Reclamation Act of 1977 (Public Law 95-87). A slide in an abandoned, unreclaimed strip mine northwest of Sheridan, Wyoming, has been analyzed as an example of a long-term slope failure in the region. This slide occurred in early 1975, some 20 years after cessation of mining. This investigation used Spencer's limiting equilibrium method and an elastic-plastic finite element method incorporating the Drucker-Prager yield criterion. This slide was found to fit the model for time-dependent failure proposed by Nelson and Thompson (1977) in which the time to failure is related to Skempton's residual factor. The Nelson-Thompson hypothesis is extended for use with the three-dimensional Drucker-Prager yield criterion. The residual factor (R) may be computed from the factors of safety with respect to peak (F(p)) and residual (Fᵣ) material properties, using either the Mohr-Coulomb or Drucker-Prager criterion, by the relationship R = [(F(p) - 1)/(F(p)-Fᵣ)] At the present time, the Spencer limiting equilibrium analysis is a more usable tool for ordinary slope design than the elastic-plastic finite element analysis because of the speed, simplicity, and ease of including the effects of ground water in the Spencer analysis.

Minerals, metals and mining are the cornerstone of technological development and play an essential role in achieving the United Nations Sustainable Development Goals. Mining, however, is not a wastefree process, with mine wastes being a source of a host of environmental problems. One of these is acid rock drainage (ARD), which forms through a complex series of acid formation (mainly via sulfide oxidation), neutralisation (primarily by carbonates) and gangue mineral dissolution reactions in waste rock and tailings storage piles. The resulting drainage waters are often acidic, highly saline and may contain elevated levels of deleterious elements. Effective ARD mitigation requires accurate ARD characterisation and prediction strategies. To date, standard guidelines recommend a suite of geochemical static (characterisation) and kinetic (prediction) tests. Characterisation tests such as acid-base accounting (ABA) and net acid generation (NAG) tests provide a quick and relatively inexpensive estimate of the "worst case" scenario for acid formation and neutralisation, while kinetic tests (commonly humidity or column leach tests) aim to predict the longterm weathering potential of waste material. The UCT biokinetic test (not currently industry standard practice) was developed to address the effect of microorganisms on ARD formation and allow for the collection of relative kinetic data on neutralisation and acidification within a shortened time period. None of these tests, however, account for the additional layer of complexity introduced by mineral texture, which describes the interrelationship of mineral grains to one another, their shapes and sizes, with some frequently studied textural parameters including mineral liberation, association, grain size distribution and particle size. Mineralogical and textural analyses are infrequently practiced in the context of ARD assessment due to the difficulty in obtaining statistically sound quantitative textural data, high costs of measurement, and standard ARD assessment protocols recommending (rather than necessitating) these assessments. An ARD assessment approach that includes static, kinetic, mineralogical and textural assessments has nonetheless been suggested by several researchers. This project assessed the dominating textural parameters on the scales of kinetic (humidity cell) test (HCT) feed material (meso-scale) and characterisation (static and UCT batch biokinetic) test (SCT) feed material (micro-scale) using four waste rock samples (A, B, C and D) from a greenstone belt gold deposit as a case study. More specifically, the study aimed to assess the role of mineralogy and texture in the ARD assessment "toolbox" and to investigate the role of coarse material sampling for ARD assessment. Data sets collected included the PSD of the micro- and meso-scale material, sample chemistry data obtained from XRF spectrometry and LECO total sulfur, bulk mineralogy data from QXRD and QEMSCAN, as well as textural and mineralogical data from QEMSCAN for sized and unsized micro- and meso-scale material. ARD-specific data sets included results of geochemical characterisation tests such as ANC and single-addition NAG tests, the UCT batch biokinetic test with and without pH control for samples C and D, as well as prediction test data from water-fed and modified humidity cell tests. The geochemical static tests performed on samples A, B, C and D classified them as PAF, PAF, uncertain and NAF, respectively. Non-pH-controlled UCT batch biokinetic tests remained circumneutral for samples B, C and D over the duration of 90 days, while for sample A the pH became acidic over time. The pH-controlled tests demonstrated a steady depletion of neutralisation potential over the first 30 days. Humidity cell test results demonstrated no acidic leachate formation for waterfed tests over 40 weeks, while modified tests showed a decreasing pH over time as the neutralisation capacity was reduced. The mineralogy was important for the interpretation of test results on both the micro-and meso-scales and was assessed in terms of both discrete minerals and reactivity groupings (Fe-Sulfide, other sulfide, dissolving (carbonate), fast weathering, intermediate weathering, slow weathering, inert and other). For sample A the mineralogy was dominated by the inert (quartz), slow weathering (magnetite, plagioclasealbite) and intermediate weathering (Fe-amphibole) categories, with lesser contributions from the FeSulfide (pyrrhotite), dissolving (calcite) and fast weathering (epidote) groups. The main groups contributing to the sample B mineralogy were the slow weathering (plagioclase-albite, magnetite, Kfeldspar), inert (quartz) and intermediate weathering (Fe-mica, chlorite) groups, followed by Fe-Sulfide (pyrite), dissolving (calcite) and fast weathering (epidote) mineral groups. Sample C mineralogy comprised predominantly inert (quartz, titanite), Fe-Sulfide (pyrrhotite), dissolving (calcite) and intermediate weathering (Fe-mica, chlorite) minerals, with lesser contributions from slow weathering (K-feldspar) and fast weathering (epidote) minerals. Sample D comprised intermediate weathering (Feamphibole, chlorite, Fe-mica) and slow weathering minerals, with lesser contributions from slow weathering (magnetite), dissolving (calcite) and Fe-Sulfide (pyrrhotite) minerals. Textural parameters (liberation and association, grain size distribution and liberation spectrum) were evaluated for the FeSulfide and dissolving minerals. On the micro-scale, a large portion of the Fe-Sulfide and dissolving minerals in the samples was found in the liberated category (50%) of the texturally significant size fractions (>1mm), which comprised predominantly locked Fe-Sulfide and dissolving minerals. Evidence of a bimodal distribution was, however, found for sample C via the liberation spectrum and grain size distribution (early liberation size of 8mm), which accounted for the larger degree of liberation observed in the >1mm size fractions, and a larger degree of liberation for the sample overall. The association of Fe-Sulfide and dissolving minerals for all samples was found to be primarily to inert, intermediate weathering and slow weathering minerals, with a larger degree of association of Fe-Sulfide to dissolving minerals observed in sample C. On the micro-scale the mineralogy helped inform the placement of the samples on the geochemical classification plot based on the Fe-Sulfide, dissolving and intermediate weathering mineral contents. For the non-pH-controlled UCT batch biokinetic test, the presence and abundance of calcite was thought to dictate the PAF/NAF nature of the test, as even relatively low amounts of calcite rendered the pH circumneutral for the duration of the test (sample B). For pH-controlled tests, however, the calcite was depleted over time, which led to a favourable acidic environment for the acidophilic bacteria used in the batch biokinetic test. For both the geochemical characterisation and the pH-controlled UCT batch biokinetic tests there was evidence to suggest the contribution of intermediate weathering (Feamphibole, Fe-mica, chlorite) and slow weathering (magnetite) minerals to the neutralisation potential in the sample. On the meso-scale the effects of mineralogy were most prominent for the modified humidity cell tests, which showed some pH fluctuations and a steady depletion of the primary neutralisation potential. The pH fluctuation after the depletion of the dissolving minerals was attributed to the dissolution of intermediate weathering minerals over the 40 weeks of the tests. These effects were not observed during the 40 weeks of the water-fed experiments. Given sufficient time for the latter test, however, it would be expected that upon the onset of acidification, similar effects of the mineralogy on the leachate quality would be observed as in the modified tests. Knowledge of the Fe-sulfide and dissolving mineral texture yielded several insights. on the micro-scale, the liberation and grain size distribution data provided an indication that a sample-customised grinding size should be established to ensure adequate "worst case" scenario determination via characterisation tests, as material with fine Fe-Sulfide or dissolving mineral grains may not be fully liberated at the recommended 75µm top size. On the meso-scale, the texture yielded insight into the circumneutral behaviour of the water-fed HCT, as most of the acid-forming minerals were contained in size fractions where the liberation was either limited or negligible, with predominant association to slow weathering, intermediate weathering and inert minerals. These findings highlighted the importance of considering mineralogy, texture and the PSD of the material for HCT result interpretation. When considering texture as a parameter for ARD assessment, the potential for sampling and mineralogical errors arose due to the coarse material size (specifically on the meso-scale) and the limitations on the number of particles that could be assessed. Quantitative mineralogy and texture data allowed for the quantitative assessment of the sampling and mineralogical errors, which were investigated through Pierre Gy's fundamental sampling error (FSE) equation, the binomial distribution approximation and the plotting of confidence intervals over the Fe-Sulfide liberation data. The results showed that although tools such as Gy's "safety line" provide a useful quick means of sampling error assessment, this approach may yield excessively large sample mass requirements for coarse material. Calculating the sampling error from the textural and mineralogical data provided a useful tool to estimate sample representativeness. Additionally, the estimation of sampling errors may help in the planning of an appropriate sampling approach, which may ultimately provide a means to relate data sets to one another across scales based on how representative samples are of one another, and therefore of the parent lot. The current study showed how mineralogy and texture are not simply "tools" in the ARD assessment "toolbox", but rather a key means for interpreting characterisation and prediction test data. Additionally, the quantitative assessment of mineralogy and texture provided the opportunity to assess the materialspecific sampling error, which, in turn, may allow for the correlation of data sets across various scales and for the planning of appropriate sampling strategies. Recommendations for future work include: the quantitative assessment of the ARDI for meso-scale material; the assessment of detailed characterisation and prediction test leachate chemistry; trace element assessment and deportment throughout UCT batch biokinetic and humidity cell testing; mineralogical and textural assessment on characterisation and prediction test residues during and after tests; an in-depth analysis of the minimal/optimal sample block/sub-sample mass required for minimal error; the assessment of samples using X-ray microcomputed tomography to assess and decrease the effects of stereological bias prevalent in 2D measurements; and the application of a similar texture and mineralogy assessment to additional waste types (such as coal wastes, or waste material containing non-Fe-bearing sulfides).

This thesis presents details of investigations into the potential for co-disposal of the two rejects from Clarence Colliery and Kable's Transport Sand Mine. Column experiments were undertaken to simulate field conditions. The experiment consisted of: 1/. creating the required co-disposal arrangement and structure in containers 2/. infiltrating water through each container and measuring the rates of infiltration and overflow 3/. measuring the chemical properties of the leachate water. Geotechnical tests of co-disposal pile stability were undertaken using a specially constructed shear box. Results of this study suggest the co-disposal of course coal washery reject from Clarence Colliery with clay tailings from Kable's Transport Sand Mine is a feasible option for managing the generation of acetic drainage. It is recommended that field trials comprise layers of coal reject and clay tailings in a 9:1 ratio. Layering the coal reject with clay tailings creates a semi-permeable barrier which acts to restrict water percolation through the reject as well as reacting with the leachate to increase the leachate pH and adsorb metals / Master of Engineering (Hons)

<p>Ensåsengruvan is a mine situated within Ljusdals municipality in central Sweden. Themine was in use from 1984 to 1991 and has since been undergoing a remediation program. Mine tailings from sulfide rich ore is a potential environmental hazard due to its tendency to cause acid waters and heavy metal leakage. Lake Ensjön is situated one kilometer from the mine area. Due to the hydrological conditions it was not expected to receive inflowing water from the mining area. A study done in 2005 showed high amounts of heavy metals in the lake.</p><p>In this study water and sediments was analyzed to confirm the results from the 2005 study. Water was sampled two times during summer 2006 from the lake and adjoining streams. Sediment samples were collected with a core sampler at ten different locations within the lake. The water and sediment samples were analyzed for heavy metal content. Sub-samples from different depths in the sediment core were extracted so that conclusions on the contamination history could be drawn. The sediments were dated trough Cs-137 analyses. The depth in the profile with the highest Cs-137 content can be dated to the time of the Chernobyl fallout (1986). After dating, relevant samples were analyzed for metal content.</p><p>The results show that Ensjön is contaminated by a local source. The surface sediments are high in copper, zinc, nickel and cadmium content. The content is high both compared to the samples from deeper in the sediment core and the surface sediments analyzed in the reference study done in 1980. The amounts of heavy metals are also high relative to the standards set by the Swedish Environmental Protection Agency. The water from the stream adjoining the lake from the mining area is high in content of the previously mentioned metals. The methods used, including sediment dating and metal analyses together with water analyses, has proven to be useful in investigating a suspected contamination from a point source.</p><p>It can be concluded that Lake Ensjön is contaminated with water from the mine waste. No other sources in the catchment area can be the source of the enriched amounts of heavy metals. Focus should in further work be put upon finding the exact source of leakage from the mining area.</p> / <p>Från Enåsengruvan i Ljusdals kommun utvanns ur sulfidmalm guld, silver och koppar under åren 1984 till 1991. Avfall från sulfidmalmsgruvor medför miljöproblem genom försurning och läckage av tungmetaller. Vanligtvis täcks avfallet med jordmassor eller vatten för att förhindra påverkan på naturen. De studier som genomfördes under prospekteringen visade på att Ensjön, som är belägen inom en kilometers avstånd från gruvområdet, inte skulle påverkas av gruvan men en provtagning under 2005 visade på höga halter av tungmetaller i sjön.</p><p>I denna studie har Ensjöns vattenkvalitet undersökts genom vatten och sedimentanalyser. Vattenprover i sjön och dess inlopp togs två gånger under sommaren 2006 och sedimentprover togs vid ett tillfälle på tio olika lokaler i sjön. En djupprofil av sedimenten analyserades för att föroreningshistoriken från innan gruvan togs i bruk till nutid skulle kunna kartläggas. För att datera sedimenten analyserades de med avseende på Cs-137. De högsta halterna av Cs-137 kan härledas till nedfallet från Tjernobylolyckan 1986. Efter datering valdes lämpliga prover ut för metallanalys.</p><p>Resultaten visar på förhöjda halter av koppar, zink, nickel och kadmium. Halterna i ytsedimenten är höga både jämfört med de halter som återfinns på större djup i sedimentprofilen, motsvarande avsättning innan gruvdriften och vad som uppmättes i referensstudien från 1980. Halterna är även höga relativt de jämförvärden som Naturvårdsverket satt upp. Vattenanalyserna visar på att vattnet i inflödet från gruvområdet innehåller höga halter av de tidigare nämnda metallerna. Metoden med Cs-137-datering och analys med avseende på metaller av sediment har visat sig fungera väl för kartläggning av en nutida förorening från en punktkälla. Tillsammans med kompletterande vattenprover ger det en bra bild av den rådande situationen.</p><p>Då resultaten visar att Ensjöns vatten är påverkat av en punktkälla och alla andra källor kan uteslutas får det anses klarlagt att sjöns vatten är påverkat av dränagevatten från gruvområdet. Fortsatta studier bör fokusera på att klarlägga den exakta källan till läckaget från gruvområdet.</p>