This thesis examines the bioleaching of six different Canadian nickel sulphide ores at pH levels above what is generally considered optimum (~ 2). The majority of work discussed in this thesis was conducted with a low-grade metamorphosed ultramafic nickel sulphide ore from Manitoba, Canada (Ore 3), which is not currently exploitable with conventional technologies. The ore contains 21% magnesium and 0.3% nickel. Nickel is the only significant metal value, and is present primarily as pentlandite. A substantial fraction of the magnesium is present as the serpentine mineral lizardite, making processing difficult with conventional pyro- and biohydrometallurgical techniques. The work with this ore has two equally important objectives: to minimize magnesium mobilization and to obtain an acceptable level of nickel extraction. Batch stirred-tank bioleaching experiments were conducted with finely ground ore ( 147 µm) with temperature and pH control. The first phase of experimentation examined the effect of pH (2 to 6) at 30 °C, and the second phase examined all combinations of three pH levels (3, 4 and 5) and five temperatures (5, 15, 22.5, 30, and 45 °C).

There is an increasing concern over the safety of engineered nanoparticles (ENPs) to humans and the environment. It is important that the environmental risks of these particles to be tested under research and regulatory schemes, e.g. Nano Risks to the environment & Human Health (NanoReTox) under Seventh Framework Programme (FP7) in EU. Due to their unique properties and the fact that their detection and characterization in complex matrices is challenging, classic analytical methods and test approaches for assessing environmental risk may not be appropriate for ENPs. In this paper I present the challenges associated with ENPs exposure to the estuarine environment and the testing of a chosen ENPs to generate data on ecotoxicity in the test estuarine organisms for further consideration of risk assessment of marine environment. Careful consideration was given to the selection of the test materials (benthic organisms Nereis diversicolor and Scrobicularia plana), the test system and the test exposure conditions (CdS ENPs and aqueous CdS added to filtered natural seawater with a concentration of 10 µg L-1). Evaluation of the exposure effects was carried out by behavioral tests (burrowing kinetics and feeding rate) and biochemical responses (quantification of biomarkers). Multispecies Freshwater Biomonitor®  (MFB) tests and GST analysis results show significant differences in between control group and CdS NPs exposure one, indicating that CdS NPs are potential to cause sublethal effects in test organisms. Our knowledge in environmental risk assessment of ENPs is still limited. Coordinated research is required to gain a better understanding of the factors and processes affecting ENP fate and effects in the environment as well as to develop more usable, robust and sensitive methods for characterization and detection of ENPs in environmental systems. / NanoReTox, FP7 NMP Work Programme

No description available.

In the north of Sweden lots of the soil is naturally contaminated by acid sulfate. When soil gets in contact with oxygen an oxidation process begins which releases elements that may be harmful to the surroundings. When the Botniabanan was built, soil had to be transported from the railroad area to deposit sites. This study was made to investigate the suspicions a landowner had regarding if his estate had been contaminated sulphide soil soil during the building of the Botniabanan. To do that four pits were dug in the area where the soil had been deposited. Then the soil was analyzed to see the content of sulfate, iron, organic matters and water. When the results was compared to other studies it showed that the content of sulfate and organic matters was to low to classify the soil as an acid sulfate soil.

Darbe analizuojami ZnS ploni sluoksniai, gauti vakuuminio garinimo būdu. Tyrimai atliekami skenuojančio zondo mikroskopijos metodu. Ištirta plonų sluoksnių paviršiaus struktūra ir įvertintas gamybos metodo kokybiškumas. Išmatavus srovių priklausomybes nuo įtampų, esant skirtingoms bandinio temperatūroms, sudarytos voltamperines charakteristikos (VACh), tokiu būdu nustatytas ZnS plėvelės laidumo mechanizmas. Įvertinta aktyvacijos energija (lygi 0,64 eV). Nustatyta, kad srovę tiriamoje struktūroje sąlygoja elektronų tuneliniai šuoliai iš paviršinių puslaidininkio būsenų dalyvaujant fononams. Remiantis gautais duomenimis galima teigti, kad vakuuminio garinimo metodu gauti ZnS sluoksniai pasižymi dideliais paviršiaus netolygumais. / The paper analyzes the ZnS thin films obtained by vacuum evaporation. Research carried out by scanning probe microscopy. The structure of thin layers surface is investigated and the quality of the production method is assessed. Measuring the voltage dependence of currents at different sample temperatures concluded voltage characteristics (VACh), thus the conduction mechanism of ZnS films was determined. Estimated thermal activation energy is 0.64 eV. It was found that the electrical current of the investigated structure is determined by tunneled electron jumps from the semiconductor surface states in the presence of phonons. Experiments results show that the ZnS layers produced by vacuum evaporation method are characterized by large surface irregularities.

The Bien Venue massive sulphide deposit is associated with a felsic volcanic succession developed in the north-eastern part of the Barberton Greenstone Belt, Eastern Transvaal. The deposit is situated 8km east-north-east of Louw's Creek between the Lily Syncline to the south and the Stentor Pluton to the north. The stratigraphy of the Onverwacht, Fig Tree and Moodies Groups in the vicinity of the deposit is poorly documented, and the exact stratigraphic position of the host felsic volcanics is not known. They are tentatively correlated with the felsic volcanics from the Theespruit Formation, Onverwacht Group. The felsic volcanics have undergone low-grade greenschist facies metamorphism and occur as quartz-sericite schists. Detailed petrography enables sub-division of the volcanic succession into distinct units. A lapilli metatuff unit hosts the base metal and precious metal mineralisation. The sulphides are best developed in the upper part of this unit, together with intercalated barite-rich horizons and cherts. A series of structural events have modified the attitude of the lithological units and disrupted the continuity of the orebody. The orebody comprises stratabound lenses of massive to semi-massive and often banded sulphides, as well as disseminated sulphide mineralisation. The dominant base metal mineralogy consists of pyrite, sphalerite, chalcopyrite, galena and tennantite. Native silver and various copper-silver sulphides are also associated with the base metal sulphides. A vertical zonation of the mineralisation exists, from pyrite-chalcopyrite-rich ore in the footwall, to pyrite - chalcopyrite-sphalerite-galena-barite-rich ore towards the hanging wall. Geochemical studies indicate that the Bien Venue lithologies are rhyolitic to rhyodacitic in composition and show a calc-alkaline affinity. The mobility of some elements at Bien Venue has been clearly demonstrated. This is believed to be associated with hydrothermal alteration that has led to SiO2 and MgO enrichment, as well as K2O depletion, in the wall rocks of the deposit. The geological setting and nature of the mineralisation at Bien Venue suggest that it is an example of a volcanogenic exhalative sulphide deposit. In terms of the classification scheme suggested by Hutchinson (1973, 1980), Bien Venue would best be described as a Primitive type deposit that contains barite. / Thesis (M.Sc.)-University of Natal, 1990

No description available.

Research goal and objective. To investigate the possibilities of the use of mineral raw materials of local origin for the purification of biogas produced from sewage sludge, by-products and waste and to assess the environmental benefits of the use of biogas in the transport sector. The properties of by-products and waste generated in Lithuania as well as the possibilities of their use in the production of biogas from sewage sludge have been assessed. The potential and properties of local mineral raw materials suitable for the purification of biogas have been assessed. The process of the removal of hydrogen sulphide and carbon dioxide from biogas using natural sorbents has been investigated. It was found that large dolomite resources available in Lithuania allow using this natural raw material for biogas purification because sorbent solutions and suspensions of dolomite powder effectively remove hydrogen sulphide and absorb carbon dioxide from biogas sufficiently quickly. A principal biogas purification technology was developed on the basis of the performed assessment of the process kinetic calculations. Engine perfomance tests were carried out using a mixture of biogas and mineral diesel fuel and exhaust gas emissions were assessed. / Darbo tikslas – ištirti gamtinių sorbentų (vietinės kilmės mineralinių žaliavų) panaudojimo biodujų, pagamintų iš nuotekų dumblo, šalutinių produktų ir atliekų, valymui galimybes bei įvertinti biodujų panaudojimo transporto sektoriuje aplinkosauginę naudą. Įvertintos Lietuvoje susidarančių šalutinių produktų ir atliekų savybės bei panaudojimo biodujų gamyboje iš nuotekų dumblo galimybės. Įvertintos vietinės kilmės mineralinių žaliavų, tinkančių biodujų valymui, potencialas ir savybės. Ištirtas biodujų valymo nuo sieros vandenilio ir anglies dioksido procesas, naudojant gamtinius sorbentus. Nustatyta, kad Lietuvoje eantys dideli dolomito ištekliai leidžia panaudoti šią natūralią žaliavą biodujų valymui, nes absorbciniai tirpalai iš dolomito miltelių efektyviai pašalina sieros vandenilį ir pakankamai gerai sugeria anglies dioksidą. Remiantis atliktu proceso kinetinių skaičiavimų įvertinimu buvo parengta principinė biodujų valymo technologija. Atlikti stendiniai variklio bandymai naudojant biodujų ir mineralinio dyzelino mišinį bei įvertintos deginių emisijos.

Research goal and objective. To investigate the possibilities of the use of mineral raw materials of local origin for the purification of biogas produced from sewage sludge, by-products and waste and to assess the environmental benefits of the use of biogas in the transport sector. The properties of by-products and waste generated in Lithuania as well as the possibilities of their use in the production of biogas from sewage sludge have been assessed. The potential and properties of local mineral raw materials suitable for the purification of biogas have been assessed. The process of the removal of hydrogen sulphide and carbon dioxide from biogas using natural sorbents has been investigated. It was found that large dolomite resources available in Lithuania allow using this natural raw material for biogas purification because sorbent solutions and suspensions of dolomite powder effectively remove hydrogen sulphide and absorb carbon dioxide from biogas sufficiently quickly. A principal biogas purification technology was developed on the basis of the performed assessment of the process kinetic calculations. Engine perfomance tests were carried out using a mixture of biogas and mineral diesel fuel and exhaust gas emissions were assessed. / Darbo tikslas – ištirti gamtinių sorbentų (vietinės kilmės mineralinių žaliavų) panaudojimo biodujų, pagamintų iš nuotekų dumblo, šalutinių produktų ir atliekų, valymui galimybes bei įvertinti biodujų panaudojimo transporto sektoriuje aplinkosauginę naudą. Įvertintos Lietuvoje susidarančių šalutinių produktų ir atliekų savybės bei panaudojimo biodujų gamyboje iš nuotekų dumblo galimybės. Įvertintos vietinės kilmės mineralinių žaliavų, tinkančių biodujų valymui, potencialas ir savybės. Ištirtas biodujų valymo nuo sieros vandenilio ir anglies dioksido procesas, naudojant gamtinius sorbentus. Nustatyta, kad Lietuvoje eantys dideli dolomito ištekliai leidžia panaudoti šią natūralią žaliavą biodujų valymui, nes absorbciniai tirpalai iš dolomito miltelių efektyviai pašalina sieros vandenilį ir pakankamai gerai sugeria anglies dioksidą. Remiantis atliktu proceso kinetinių skaičiavimų įvertinimu buvo parengta principinė biodujų valymo technologija. Atlikti stendiniai variklio bandymai naudojant biodujų ir mineralinio dyzelino mišinį bei įvertintos deginių emisijos.

The five discrete, but related studies presented in this thesis investigate several aspects of the physiology and biochemistry of whole animals, perfused and isolated tissues from fishes and other vertebrates. Important fundamental questions about tissue metabolism and energy supply and utilisation in relation to oxygen supply, in addition to applied questions relating to commercial harvesting and post-mortem muscle physiology were addressed. Oxyconformance of oxygen consumption (VO2) at low oxygen delivery rates was shown using an isolated, perfused salmon tail preparation, composed primarily of skeletal muscle. Addition of pig red blood cells to the perfusing solution at a haematocrit of 5 or 10%, increasing the capacitance, resulted in oxyregulation of VO2 by the tail tissues. Below c.60 ml O2.kg-1.h-1 of oxygen delivery, VO2 was delivery dependent. Above this value additional oxygen delivery did not increase VO2 of resting muscle above c.35 ml O2 kg-1.h-1. The preparation was validated by measuring mitochondrial activity using MTT and blood flow distribution to the red and white muscle using fluorescent microspheres. Evidence of both O2-independence of VO2 in the vasculature and strict O2-dependence of VO2 in striated muscles of fishes and a mammal is presented using isolated vascular tissue and an in vitro tissue slice model. VO2 by vessels from rat, salmon and hagfish showed varying degrees of independence between PO2s of 15-95 mmHg in vitro (1 mmHg = 0.133 kPa). Above and below these values, VO2 was highly PO2-dependent. VO2 by cardiac and skeletal muscles from rat, salmon, snapper and hagfish were shown to relate linearly to PO2 between zero and 125 mmHg. VO2 in these tissues was highly dependent on tissue type (cardiac, red and white muscle) which correlated with haem protein concentration. The increase in VO2 in muscle slice mitochondria uncoupled with FCCP and DNP ruled out diffusion-limitation as a constraint on VO2. Mitochondrial activity was constant over time and reoxygenation of the Ringer bathing the tissues after the initial run down in PO2 resulted in VO2 rates that were unchanged from the starting values, demonstrating that the tissues remained viable over time. ATP turnover in red muscle was significantly increased at 100 mmHg relative to 30 mmHg, and increased in both treatments from values at the start. Our data suggest that ATP supply and ATP demand were reduced in conjunction with falling PO2. The effects of hydrogen sulphide (H2S) (derived from Na2S) and isoeugenol exposure on activity, VO2 and ventilation frequency (Vf) in a teleost fish are reported. In the H2S treatment group (200 μM Na2S) both resting VO2 and Vf decreased after 30 minutes of exposure, concurrent with narcosis and a loss of equilibrium. These events corresponded with a significant fall in VO2 (33%) and Vf (20%) by 15 minutes, both declining further to a nadir of 40% of resting values at 30 minutes. After flushing, VO2 increased to resting levels, with Vf remaining significantly depressed until 30 minutes of recovery. Recovery was accompanied by regained mobility and equilibrium and significantly increased VO2 and Vf. Isoeugenol anaesthetised fish (0.011 g.L-1) reached stage 4-5 of anaesthesia accompanied by significant decreases in VO2 (45%) and Vf (25%) at 25 minutes, both parameters declining further to around 64% and 38% respectively by 35 minutes. Similar to H2S exposed fish, VO2 increased to resting values after flushing, followed by a significant rise in VO2. Likewise, Vf had risen to resting values post-flushing, subsequently increasing significantly during recovery. Overall, VO2 in relation to resting rate was reduced in the isoeugenol treated animals, while in H2S treated fish, exposure there was increased oxygen usage, possibly associated with a toxic effect. H2S significantly reduced cytochrome c oxidase activity in muscle and gill tissue in vitro between 69-79% at 20 μM and 77-97% at 200 μM Na2S, while isoeugenol had no effect on activity in any tissue. Calorimetric and biochemical profiles of anoxic, post-mortem white muscle from Chinook salmon subjected to rested and exhausted harvesting regimens at their acclimation temperature (10°C) are reported. Prior to harvest rested animals were anaesthetised with 0.012 g.L-1 isoeugenol without disturbance. The muscle of these animals had a high metabolic rate at the time of death, at around 400 μW.g-1, which declined rapidly over the first 12 hours to15 μW.g-1. Exhausted animals were forced to swim and were crowded before capture, resulting in an initial heat output of <10 μW.g-1. Heat output was significantly greater in the rested group at the time of death and for 7 hours post-mortem. In both groups there was an exothermic event, occurring between 4 and 6 hours post-mortem amounting to a rise of around 35 μW.g-1. A one-phase exponential decay model appropriately described the net heat output of the rested profile minus the exhausted data. Rested animals had significantly higher initial cut surface pH (7.5 vs 6.7), tissue glycogen (16 vs 2 μmol.g-1), creatine phosphate (18 vs 0.1 μmol.g-1), ATP (6 vs 3.5 μmol.g-1) and potential energy (30 vs 7 μmol.g-1) than the exhausted group, which had significantly elevated tissue concentrations of lactate (43 vs 18 μmol.g-1) and glucose (5 vs 2 μmol.g-1). Potential energy in the form of ATP, glycogen and creatine phosphate remained elevated for an extended period post-mortem in rested animals while catabolites further down the chain such as inosine, hypoxanthine and uric acid accumulated at similar rates in both groups. We examined the relationship between exogenous and endogenous H2S and oxygen partial pressure in isolated hagfish and lamprey vessels that exhibit profound hypoxic vasoconstriction (HVC). In myography studies, H2S (Na2S) dose-dependently constricted dorsal aortas (DA) and efferent branchial arteries but did not affect ventral aortas or afferent branchial arteries, which was similar to the effects produced by hypoxia. Sensitivity of H2S-mediated contraction in hagfish and lamprey DA was enhanced by hypoxia. HVC in hagfish DA was enhanced by the H2S precursor cysteine and inhibited by amino-oxyacetate (AOA), an inhibitor of the H2S-synthesising enzyme, cystathionine β-synthase, and unaffected by propargyl glycine, an inhibitor of cystathionine λ-lyase. Oxygen consumption (MO2) of hagfish DA was constant between a PO2 of 15 and 115•mmHg, decreased when PO2 <15•mmHg, and increased if PO2 exceeded 115•mmHg. 10 μmol.l-1 H2S increased and concentrations above 100 μmol.l-1 H2S decreased MO2. Consistent with the effects on HVC, cysteine increased and AOA and hydroxylamine, an inhibitor of pyridoxyl 5’-phosphate-dependent enzymes, decreased MO2. These data show that H2S is a monophasic vasoconstrictor of specific cyclostome vessels and because hagfish lack vascular NO, and vascular sensitivity to H2S was enhanced at low PO2, it is unlikely that H2S contractions are mediated by either an H2S-NO interaction or an oxidation product of H2S. These experiments provide additional support for the hypothesis that the metabolism of H2S is involved in oxygen sensing/signal transduction in vertebrate vascular smooth muscle. Together the findings of this thesis contribute to the understanding of oxygen utilisation and energetics in relation to oxygen supply in a number of tissues. These data further our understanding of respiratory physiology and may have practical applications in the seafood industry.