Rikastushiekan ja peittomoreenin mineraloginen ja geokemiallinen karakterisointi Rautuvaaran rikastushiekka-altaan keskiosassa

Tiivistelmä. Rikastushiekka on malminrikastuksen yhteydessä syntyvää, jätteenä pidettävää sivukiviainesta, joka läjitetään vesilietteenä loppusijoituspaikkaan, tyypillisesti rikastushiekka-altaaseen. Metallikaivostoiminnan aikana syntyneet rikastushiekat sisältävät usein merkittäviäkin määriä rikkipitoisia sulfidimineraaleja, jotka hapettuessaan voivat tuottaa happamia valumia sekä päästää haitallisia metalleja ympäristöönsä. Muun muassa näistä ympäristögeologista syistä rikastushiekoille suoritetaan karakterisointimenettelyjä. Näiden menettelyjen tarkoituksena on esimerkiksi selvittää rikastushiekkojen koostumusta rikastushiekka-altaiden jälkihoitotoimenpiteitä suunnitellessa. Tässä pro gradu -tutkielmassa suoritettiin mineraloginen ja geokemiallinen karakterisointi Rautuvaaran rikastushiekka-altaan rikastushiekalle sekä altaan jälkihoidollisena peittomateriaalina käytettävälle moreenille. Karakterisointi tehtiin osana EAKR-rahoitteista Biopeitto-projektia ja karakterisoinnin tarkoituksena oli tutkia projektin tutkimusalueen rikastushiekan ja peittomoreenin mineralogista ja geokemiallista koostumusta peilaten niitä alkuperäisiin rikastushiekkaa synnyttäneisiin malmeihin, sekä tutkia rikastushiekkojen ja moreenin raekokojakaumaa. Tutkimuksissa saatiin selville, että ulkonäöltään neljän erilaisen rikastushiekkakerroksen näytteenottohorisontti koostuu kahdesta, mineralogiselta, geokemialliselta ja raekokokoostumukseltaan täysin erilaisesta rikastushiekasta. Kolme ensimmäistä kerrosta edustavat todennäköisesti suurelta osin Saattoporan malminrikastuksessa syntynyttä rikastushiekkaa ja pohjimmainen kerros edustaa Pahtavuoman malmia. Alkuaineanalyysit paljastivat, että tiettyjen ympäristölle haitallisten aineiden, kuten arseenin pitoisuudet ovat korkeat ja peittämättöminä nämä saattavat pitkällä aikavälillä lähteä liikkeelle pidemmälle ympäristöön. Lisäksi sekundäärimineraalien kartoituksessa selvisi, että kaksi ylintä kerrosta ovat eniten muuttuneita. Muuttuneisuus ilmenee primääristen mineraalirakeiden reunoilla näkyvinä sekundäärisinä reunuksina. Reunukset olivat koostumukseltaan pääsääntöisesti Fe-oksihydroksideja, rautasulfaatteja sekä Fe-hydroksisulfaatteja.Geochemical and mineralogical characterization of tailing sand and covering till in the centre of Rautuvaara tailing sand area. Abstract. Tailing sand is gangue minerals containing mining waste which is formed during ore enrichment. This, usually sulfide minerals containing waste material is deposited as slurry in tailings pond. Sulfide minerals tend to oxidize under the conditions of earth’s surface. Oxidation of sulfides may lead to release of a metalliferous and acidic mine waters. Therefore, tailings are characterized. The purpose of the characterization procedure among other things is to investigate waste’s mineralogy and geochemistry. In this master’s thesis the mineralogical and geochemical characterization of the tailing sands and till (cover material) of the Rautuvaara tailings pond will be done. The purpose of the study was to investigate the mineralogical and geochemical composition of the diverse tailing sands deposited in Rautuvaara, located in Western Lapland, Finland. The characterization included also grain size studies and mapping of the secondary alteration of the tailings. The study has been done as part of the ERDF funded Biopeitto Project. The studies revealed that the sample horizon of four different layers contain of two mineralogically and geochemically different tailing sands. Three uppermost layers most likely represent the Saattopora gold ore and the fourth layer represents the Pahtavuoma ore. Elementary analysis revealed that some heavy metal concentrations such as arsenic concentrations in the tailings are considerably high and leaving the tailings pond uncovered could be hazardous for environment in the long run. The secondary mineral studies showed that the first and the second layer are the most altered layers. This alteration appears as the secondary rims of Fe-oxyhydroxides, iron sulfates and Fe-oxyhydroxysulfates at the edges of primary mineral grains

Teknologian hyödyntäminen kuvataidekasvatuksessa

Tiivistelmä. Kasvatustieteiden kandidaatin tutkielman aiheena on teknologian hyödyntäminen, ja sen käytön perustelu kuvataidekasvatuksessa. Pohdin myös kahden toisistaan eroavan käsitteen, teknologian ja taiteen, suhdetta toisiinsa. Mietin myös sitä, miten kaksi alaa voidaan mielekkäästi integroida toisiinsa, ja miten taiteellinen toiminta näkyy molemmissa. Kiinnostus ja motivaatio aihetta kohtaan tulee omista harrastuksista ja mielenkiinnon kohteista, joita ovat kuvataide sekä kuvankäsittely. Tutkielmassa on keskeinen hypoteesi, joka on se, että teknologiaa voidaan tuoda monipuolisesti kuvataidekasvatuksen kentälle, ja että kuvataide antaa uusia näkökulmia teknologian tarkasteluun. Tutkielmassani tarkastelen taidekasvatuksen ja teknologiakasvatuksen piirteitä, ja etsin samankaltaisuuksia ja eroavaisuuksia näiden kahden välillä. Teknologia näyttäytyy tutkielmassa teknologisina välineinä ja yhteiskunnallisina rakenteina, kun taas taide ja estetiikka näyttäytyvät inhimillisinä aistien erilaisina ulottuvuuksina, jotka tarjoavat kokemuksia, jotka tarjoavat perustan merkityksien luomiselle ja lopulta oppimiskokemuksille. Vaikka lähestynkin tutkielmassa vahvasti teknologiaa ja teknologiakasvatusta, tutkin asiaa lähtökohtaisesti taidekasvatuksellisesta ja kulttuurisesta näkökulmasta

Methane dynamics in different boreal lake types

This study explores the variability in concentrations of dissolved CH<sub>4</sub> and annual flux estimates in the pelagic zone in a statistically defined sample of 207 lakes in Finland. The lakes were situated in the boreal zone, in an area where the mean annual air temperature ranges from −2.8 to 5.9°C. We examined how lake CH<sub>4</sub> dynamics related to regional lake types assessed according to the EU water framework directive. Ten lake types were defined on the basis of water chemistry, color, and size. Lakes were sampled for dissolved CH<sub>4</sub> concentrations four times per year, at four different depths at the deepest point of each lake. We found that CH<sub>4</sub> concentrations and fluxes to the atmosphere tended to be high in nutrient rich calcareous lakes, and that the shallow lakes had the greatest surface water concentrations. Methane concentration in the hypolimnion was related to oxygen and nutrient concentrations, and to lake depth or lake area. The surface water CH<sub>4</sub> concentration was related to the depth or area of lake. Methane concentration close to the bottom can be viewed as proxy of lake status in terms of frequency of anoxia and nutrient levels. The mean pelagic CH<sub>4</sub> release from randomly selected lakes was 49 mmol m<sup>−2</sup> a<sup>−1</sup>. The sum CH<sub>4</sub> flux (storage and diffusion) correlated with lake depth, area and nutrient content, and CH<sub>4</sub> release was greatest from the shallow nutrient rich and humic lakes. Our results support earlier lake studies regarding the regulating factors and also the magnitude of global emission estimate. These results propose that in boreal region small lakes have higher CH<sub>4</sub> fluxes per unit area than larger lakes, and that the small lakes have a disproportionate significance regarding to the CH<sub>4</sub> release

Shape coexistence at the proton drip-line: First identification of excited states in 180Pb

Excited states in the extremely neutron-deficient nucleus, 180Pb, have been identified for the first time using the JUROGAM II array in conjunction with the RITU recoil separator at the Accelerator Laboratory of the University of Jyvaskyla. This study lies at the limit of what is presently achievable with in-beam spectroscopy, with an estimated cross-section of only 10 nb for the 92Mo(90Zr,2n)180Pb reaction. A continuation of the trend observed in 182Pb and 184Pb is seen, where the prolate minimum continues to rise beyond the N=104 mid-shell with respect to the spherical ground state. Beyond mean-field calculations are in reasonable correspondence with the trends deduced from experiment.Comment: 5 pages, 4 figures, submitted to Phys.Rev.

First observation of excited states in 173Hg

The neutron-deficient nucleus 173Hg has been studied following fusion-evaporation reactions. The observation of gamma rays decaying from excited states are reported for the first time and a tentative level scheme is proposed. The proposed level scheme is discussed within the context of the systematics of neighbouring neutron-deficient Hg nuclei. In addition to the gamma-ray spectroscopy, the alpha decay of this nucleus has been measured yielding superior precision to earlier measurements.Comment: 5 pages, 4 figure

Search for Fingerprints of Tetrahedral Symmetry in 156Gd^{156}Gd

Theoretical predictions suggest the presence of tetrahedral symmetry as an explanation for the vanishing intra-band E2-transitions at the bottom of the odd-spin negative parity band in $^{156}Gd$. The present study reports on experiment performed to address this phenomenon. It allowed to determine the intra-band E2 transitions and branching ratios B(E2)/B(E1) of two of the negative-parity bands in $^{156}Gd$.Comment: presented by Q.T. Doan at XLII Zakopane School of Physics: Breaking Frontiers: Submicron Structures in Physics and Biology, May 2008. 5 pages, minor corrections. To be published in the proceeding

Could continuous cover forestry be an economically and environmentally feasible management option on drained boreal peatlands?

Environmental and economic performance of forestry on drained peatlands was reviewed to consider whether continuous cover forestry (CCF) could be a feasible alternative to even-aged management (EM). CCF was regarded feasible particularly because continuously maintaining a tree stand with significant transpiration and interception capacity would decrease the need for ditch network maintenance. Managing CCF forests in such a way that the ground water levels are lower than in clear-cut EM forests but higher than in mature EM forests could decrease greenhouse gas emissions and negative water quality impacts caused both by anoxic redox reactions and oxidation and mineralization of deep peat layers. Regeneration studies indicated potential for satisfactory natural regeneration under CCF on drained peatlands. An economic advantage in CCF over EM is that fewer investments are needed to establish the forest stand and sustain its growth. Thus, even if the growth of trees in CCF forests were lower than in EM forests, CCF could at least in some peatland sites turn out to be a more profitable forest management regime. An advantage of CCF from the viewpoint of socially optimal forest management is that it plausibly reduces the negative externalities of management compared to EM. We propose that future research in drained peatland forests should focus on assessing the economic and environmental feasibility of CCF.Peer reviewe

Parkinson's disease detection from 20-step walking tests using inertial sensors of a smartphone: Machine learning approach based on an observational case-control study

Parkinson's disease (PD) is a neurodegenerative disease inducing dystrophy of the motor system. Automatic movement analysis systems have potential in improving patient care by enabling personalized and more accurate adjust of treatment. These systems utilize machine learning to classify the movement properties based on the features derived from the signals. Smartphones can provide an inexpensive measurement platform with their built-in sensors for movement assessment. This study compared three feature selection and nine classification methods for identifying PD patients from control subjects based on accelerometer and gyroscope signals measured with a smartphone during a 20-step walking test. Minimum Redundancy Maximum Relevance (mRMR) and sequential feature selection with both forward (SFS) and backward (SBS) propagation directions were used in this study. The number of selected features was narrowed down from 201 to 4-15 features by applying SFS and mRMR methods. From the methods compared in this study, the highest accuracy for individual steps was achieved with SFS (7 features) and Naive Bayes classifier (accuracy 75.3%), and the second highest accuracy with SFS (4 features) and k Nearest neighbours (accuracy 75.1%). Leave-one-subject-out cross-validation was used in the analysis. For the overall classification of each subject, which was based on the majority vote of the classified steps, k Nearest Neighbors provided the most accurate result with an accuracy of 84.5% and an error rate of 15.5%. This study shows the differences in feature selection methods and classifiers and provides generalizations for optimizing methodologies for smartphone-based monitoring of PD patients. The results are promising for further developing the analysis system for longer measurements carried out in free-living conditions

Level structure of 99Nb

The β decay of 97Sr to 97Y has been investigated using ion-guide on-line mass separation and a 10 Ge-detector array to record γ−γ coincidences to a detection limit well below that of former studies. Similarities are found in the β-decay patterns of 99Zr and of its isotone 97Sr and also in the γ-ray decay rates and branchings of the corresponding levels in their respective daughters 99Nb and 97Y. This indicates a persisting influence of the d5/2 neutron shell closure for 99Nb. The level structure of 99Nb and the β-feeding pattern are discussed in the frame of the interacting boson-fermion plus broken pair model and the microscopic quasiparticle phonon model