Browsing by discipline "Geology"

137Cs is an artificial isotope generated by fission reactions, whose deposition times are well known both globally and locally. The 137Cs dating method measures the 137Cs activity in sediment layers from different depths, and by utilizing knowledge of the deposition moment dating accuracy can be up to one year. The prerequisites of the dating method are not only the knowledge of precise moments of deposition, but also calm sedimentation and understanding of the sediment disturbances. The best destinations for using the 137Cs dating method are deep basin sediments, where bioturbation is very low and sedimentation is calm. This study looked at the accuracy and reliability of the 137Cs dating of the bottom sediment from five different lakes. There were clear annual varves in four out of five lakes, so the sediment was not mixed and mechanical movements of 137Cs had not occurred. The most significant fall-off affecting Finland in 1986 was the Chernobyl nuclear accident and when analyzing sediment samples in 1986, it could even be traced back to a single varve. Another significant 137Cs fall-off has been the nuclear tests of the 1950s to 1960s. The 137Cs peak of these events was almost invisible compared to the 137Cs activity of 1986. Regardless of the limnological features of the lake, 1986 had also migrated downward in the analysis results. The more porous sediment was, the stronger the spread had occurred. According to the results of this study the 137Cs dating method is still usable, especially in Finland at the time of the Chernobyl nuclear accident of 1986. From 1950 to 1960, the time of nuclear testing, this method is far more uncertain in Finland, although the marker horizon is more globally distinguishable. However, downward migration of 137Cs was clearly evident even in a calm sedimentation environment, which is a major hindrance to the method. Chemical follow-up studies would be useful to clarify the causes of migration.

Äänekosken Energia Oy is planning an artificial groundwater recharge plant in Äänekoski Central Finland. Consulting company Ramboll is in charge of the water intake project that is situated at an important groundwater recharge area, Kulopalokangas. The aim of this study is to collect data from previous studies in the area, create a three-dimensional geological model of the study area's bedrock surface and sediments as well as discuss their effect on groundwater flow. Further objective is to test modelling software Leapfrog Geo and its suitability in this type of study. The study area is characterized by an esker formation that was deposited during the deglaciation of the Weichselian glaciation. This esker originates from a end moraine formation in Central Finland that formed at the rim of the continental ice sheet about 11 000 years ago. The bedrock is relatively homogenous and there are no faults. The bedrock is considerably exposed in the area and the sediment package consists of coarse sand and gravel units in the central part of the study area, whereas finer material is located at the rims and on the outside of the esker. Geological and geophysical investigations have been conducted previously within the water intake project. The data used in this study was gathered from seismic refraction surveys, drilling data and groundwater table measurements. The input data was in point data and drill hole format, and the surfaces and volumes of soil units were created subsequently. Cross sections were created to illustrate inner structures of the sediments throughout the area. The results are presented as a digital elevation map of bedrock, a groundwater map, images and cross sections of the model. They show the distribution of soil units. In addition, they provide information of the areas for artificial recharge as well as factors effecting the groundwater flow. The bedrock surface forms a NW-SE oriented depression valley that is filled with soil units. A two-meter thick unit of till is located above the bedrock and the innermost coarse gravel unit of the esker shows an elongated dome-like structure. The topmost unit is fine sand or silt at the western side of the esker, whereas the eastern side top unit is mostly composed of sand and coarse sand. Results of this study correspond with the previous studies. The three-dimensional soil model is used as a basis for a numerical groundwater flow model in the next stage of the project. The model is a simplified representation of the area and the results are absolute only at the vicinity of the observation points. The three-dimensional geological model offers more accuracy and information about subsurface geological conditions and furthermore helps to communicate between different stakeholders.

A mining facility is planned to Hannukainen, Kolari, where iron, copper and gold will be enriched. The brown-field of Rautuvaara in the Niesajoki valley is one of the options for the tailings disposal area in the environmental assessment plan. It has been used by the Rautuvaara and Saattopora mines to dispose tailings from 1962 to 1995. The target of the study was to define groundwater table and directions, hydrostratigraphical features and water qualities as well as research groundwater – surface water interactions in order to evaluate the present state and possibility for future use as a tailings disposal area. The hydraulic gradient was delineated with ArcGIS to be towards the center part of the valley and a watershed was identified in the middle part of the northern settling pond. The hydraulic pattern was simple. Mostly, the valley is covered by till, with some alternating sand, gravel and silt units. No good aquitards were identified with permeabilities calculated from grain-size analysis and slug tests. However, the hydraulic conductivity was determined to be poor or moderate (from 10^-2 to 10^-7 m s^-1) in the till units, they dominated in the area. The surrounding surface and groundwaters followed the baseline in the area for the most and were determined to be natural waters (calciumhydrogencarbonate) with Aquachem software. Contaminated (acid mine drainage) surface and groundwaters (sulphate-magnesium) were quite restricted in area, they were identified in surface waters and groundwater observation wells close by the abandoned tailings area. Some of these groundwater observation wells were evaluated to contain surface water by their oxygen and hydrogen ionic compositions, where others of the evaporated observations wells situated near a bog area. Groundwater seepage from the west coast was also concluded, which could have had a part in the AMD generation process. On the other hand, some of the wells contained enriched waters, in form of elevated trace element concentrations, however they were still Ca-HCO3 waters. This was the case for two artesian monitoring wells on the tailings area. It was concluded that the existing peat layer underneath the tailings is impermeable and leads to the assumption that mostly the contamination is restricted in area because of a separate tailings water body. The tailings waters had only very limited connection to the confined aquifer underneath. The thickness of the peat layer should be examined as well as the hydrostratigraphy of the aquifer, to prevent any future leaking risks to the groundwaters.

Five granulite xenoliths entrained in the ~600 Ma Lahtojoki kimberlite pipe in eastern Finland represent the lower crust below the suture zone between the Archaean Karelian craton and the Paleoproterozoic Svecofennian terranes. They provide direct information on the petrology of the lower cratonic crust, and the processes that controlled its evolution. Studied xenoliths comprise a dry intermediate garnet granulite, three mafic garnet granulites with amphibole contents ranging from 3–50 vol–%, and a peraluminous micaceous garnet gneiss. Granulites have granoblastic fabrics with mineral assemblage Grt – Cpx – Plg ± Amb ± Qtz ± Ilm ± Rt ± Bt, with pink garnet and green clinopyroxene. Gneiss is coarse grained with a heavily deformed and strained fabric with mineral assemblage Qzt – Bt – Grt – Sil. Mineral chemistry based TWEEQU–thermobarometry indicates equilibration of mafic granulites at ca. 800 °C and 9.5–10.5 kbar and intermediate granulite at ca 800 °C and 17.5 kbar. The pressure estimates correspond to crustal depths of 38–55 km. Equilibration temperature for garnet gneiss is ca. 700 °C – TWEEQU based pressure estimate was not possible, but based on Grt–Sil stability equilibration pressure can be constrained to ca. 4–8.5 kbar. Mineral zonation indicates slight post peak cooling and decompression of some samples. Whole-rock geochemical composition (major and trace elements) implies derivation of dry (<10 vol–% Amb) mafic granulite from a Ni-Cr fractionated basaltic melt. Enrichment in LREE and other trace elements suggests a low to moderate degree of melting of a primitive mantle source. The sample could represent a mafic underplate crystallized in situ. Amphibole and enrichment in K and Rb could indicate a later metasomatic enrichment event. The intermediate granulite is anomalous in composition compared to other Kaavi-Kuopio lower crustal xenoliths. REE composition, depletion in K, Rb, Zr, Hf, Nb, Ta, and strong enrichment in Sr and a prominent positive Eu anomaly imply that the sample represents a restitic residue after partial melting, possibly of a plagioclase cumulate protolith. The results add on to earlier xenolith studies performed in eastern Finland. Restite formation indicates that partial melting of lower crust occurred under Kaavi-Kuopio. LILE enrichment and abundant hydrous phases in many samples suggests metasomatic events, possibly coincident with the partial melting events.

Critical metals are defined as rare specialty metals (e.g. Be, Sc, Co, Ga, Ge, Nb, REEs, In, Ta) that are critical for the facilitation of the Strategic Energy Technology Plan set by the European Union. These rare metals are typically associated with highly evolved granitic ores. Trioctahedral micas are often one of the main, if not sole, hydrous ferromagnesian phases in these granite-related rare metal deposits. Since many critical metals are readily incorporated in the mica crystal structure, micas are often used as petrogenetic indicators in assessing granite melt evolution. This study is a preliminary investigation in the critical metal distribution of trioctahedral micas in Fennoscandian S-I-A type granites. Ten granite samples (6 A-type, 2 S-type, and 2 I-type samples) were selected for examination that represent three distinct areas within the Fennoscandian shield: the Paleoproterozoic Wiborg rapakivi batholith (A-type) in southeastern Finland, the Paleoproterozoic Västervik metasedimentary formation (S-type) in southeastern Sweden, and the Neoarchean Hattu schist belt (S- and I-type) in eastern Finland. Whole-rock major and trace element chemistry was determined via WD-XRF, mineral major element chemistry via WDS-EPMA, and mineral trace element chemistry via LA-ICP-MS. The A-type granites are predominantly ferroan, alkali-calcic, and metaluminous, whereas the S- and I-type granites are predominantly magnesian, calc-alkalic, and peraluminous. Trioctahedral micas in the A-type granites are characteristically annitic, whereas S- and I-type granites trend progressively towards more phlogopitic compositions. Trace element data indicates that most critical and rare metal abundances (Li, Be, B, Sc, Ga, Ge, Zr, Nb, In, Sn, Ta) tend to increase with progressing fractionation, but largely independent from granite type. Moreover, the absolute differences in abundances are often small, but distinct. However, owing to their more primitive character, I-type granites are typically less fractionated than A- and S-type granites, and thus contain lower amounts of critical and rare metals. Furthermore, it is indicated that the fractionation of the following elements may be correlated: Be & Al, Be & Sc, and In & Sc. Moreover, it is indicated that amphibole and muscovite minerals may incorporate Be, Sc, Zr, and In more readily than trioctahedral micas.

Ecometric analysis allows one to identify relationships between traits measured in organisms and conditions measured in the organisms' local environment. In developing an ecometric model, one selects phenotypic features of organisms which potentially are adaptations to local environment, aggregates measures of these features by organismal community, and quantitatively relates these to measures of the environment via statistical modeling, such that organismal traits may be used to predict environmental conditions. Once established, these models may be applied to fossil assemblages, to reconstruct local paleoenvironment using traits preserved in the fossil record. In this ecometrics case study, we addressed a number of related research questions: what bioclimatic and threshold measures of temperature and/or precipitation are most closely correlated with large, herbivorous mammal communities' mean hypsodonty (HYP) in sub-Saharan Africa? Do these correlations differ at differing spatial scales; specifically, do mammal communities in Kenya's national parks and reserves together relate differently to local environment than do communities in the Afrotropics ecoregions? Finally, what do results obtained by ecometric analysis suggest concerning organismal evolution and dispersal in sub-Saharan Africa? In pursuing answers to these questions, we also pursued the case study's primary objective: we developed and implemented a set of best practices for ecometric analysis, based on an assessment of the sensitivity of ecometric models to model-building decisions, and to uncertainty in source datasets. Ecometric analyses frequently make use of raster datasets - continuous coverages of temperature, precipitation, productivity, and other environmental properties - in characterizing local environment at study localities. Thus we primarily asked: are ecometric results dependent on raster resolution or resampling algorithm? Results of these sensitivity analyses are encouraging. Using the recommended mean resampling algorithm, change in linear regression equations with raster resolution is predictable, and not significant until very low resolutions, in which the average raster cell area is an order of magnitude or more greater than the average locality area. Moreover, using the recommended area-weighted averaging in calculating environmental observations at localities ameliorates this predicable trend in derived regressions. In working 'behind the scenes' addressing these methodological questions, we enable more informed interpretation of ecometric results, and allow future researchers to proceed to the real business of ecometrics with a vetted set of analytical methods. Moreover, in promoting better understanding of ecometric results, we promote better understanding of the complex relationships between organisms and environment, essential to understanding the biosphere's past and present, and to protecting it in the future.

Multiple anthropogenic stressors on lake ecosystems demand effective measures towards improved protection and management of water bodies. The Water Framework Directive defines a common goal for sound water management and obliges EU member countries to monitor and protect the ecological status and water quality of all relevant surface waters. However, major problems hindering the attempts for effective water management are the lack of long-term observational data on reference status and an inadequate understanding of the responses of lake ecosystems to environmental pressures. With this regard, paleolimnological techniques are invaluable as they provide means to seek for past analogies of lake-environment interactions. Long-term development in the water quality and ecological status of Lake Storträsk, located in southern Finland, was assessed using a variety of paleolimnological proxies. The aim was to determine the reference status of this dystrophic lake, and to attain holistic understanding of late Holocene environmental changes and their influences on the lake's status. The principal hypothesis of the study was that late Holocene climate changes, catchment development and contemporary human activities have affected the status of the lake leaving records in the abiotic and biotic features of the sediment deposits. A 43-cm sediment core was obtained from the lake basin and studied for its physicochemical and biological attributes. The core was dated with radiometric methods, and a time frame of ca. 4500 years was established for the sediment sequence. Loss-on-ignition and magnetic susceptibility were measured and the elemental content of the sediment was assessed by ICP-MS- and CNS-analyses. Fossil diatom assemblages were studied to reconstruct long-term development in lake-water pH. Ordination techniques and diversity indices were applied to identify temporal patterns and relationships in the bioassemblages, and Spearman's correlation coefficients were calculated to assess statistical relationships between the studied abiotic and biotic parameters. The results reveal that, whereas long-term climate changes have had the most profound impact on the water quality and ecology of Lake Storträsk, the status of the lake has also been altered by early catchment disturbances and historical human activities as well as more intensive anthropogenic disturbances after the establishment of intensive agriculture in the area. The base of the sediment core reflects the transition from the warm and dry Holocene Thermal Maximum to the cooling and increasingly humid late Holocene. After the initial phase, a more stable development took place, disrupted by possible signs of forest fires and early clearance periods in the area. From the late Middle Ages onwards, human activities within the vicinity of the lake became more intensive leaving highly distinct marks in the sediment, but were receded towards the present. Regardless of the current location of Lake Storträsk in a conservation area, and the apparent inability of the barren catchment to support any intensive agricultural practices, it is clear that human influences on the lake have been significant. The results of this study highlight the importance of long-term perspective in the assessment of lake reference conditions since lake ontogeny is often far from linear. Furthermore, this study emphasizes the importance of combining information from multiple paleolimnological proxies as they provide a more robust and holistic basis for understanding lake-environment dynamics particularly in humic boreal lakes which often respond to environmental change in distinct ways.

The Pleistocene (2588-11,2 ka) is known as the time of the ice age. The ice age ended at the beginning of the warm and more humid Holocene. Large carnivorous predators, which survived the transition, have adapted to the current new environments. The goal of this thesis was to compare the osteological changes in the large carnivores from the Pleistocene to present. The data consists Finnish Recent and Central European fossil carnivore carnassial teeth, the calcaneum and the femoral head. Body mass estimates and carnivory indexes were taken from the carnassial tooth, the calcaneal indices were used to determine environmental openness and femoral head measurements indicated locomotory category. The femoral head changes have not been tested on carnivores, so the applicability to carnivores was also tested. The wolf (Canis lupus), the wolverine (Gulo gulo) and the bear (Ursus arctos) are smaller Recently than in the Pleistocene. Wolf's diet has changed to more omnivorous, and changes in the calcaneum indicate more closed habitats. There are no significant intraspecific differences in Finnish carnivore populations between latitudes. The femoral head indices confirm the benefits of certain osteological traits in terrestrial animals (the wolf, the wolverine, the bear) compared to the traits of a more scansorial ambush predator, the lynx (Lynx lynx). The decline in the body masses from Pleistocene to Recent has been known previously. The changes in the body masses in Finland have not been made. The lack of intraspecific differences reflects constant environmental conditions throughout Finland. The differences between fossil and Recent wolf bring new insight on the matter. The more closed environments in Finland are reflected in the wolf, and differences in locomotion between species can be detected from the material.

The northern peatlands are significant sources of methane into the atmosphere. As methane (CH4) is a powerful greenhouse gas, understanding the mechanics of peatland CH4 production/consumption and the controls on CH4 emissions are vital in order to calculate global CH4 budgets. The isotopic composition of CH4 can be used as a tool to identify pathways of methanogenesis, CH4 oxidation and transport. The aim was to learn how microtopography effects CH4 emission and its δ13C values at a boreal mire complex Siikaneva, located in southern Finland. The study sites were an ombrotrophic bog and a minerotrophic fen. The hypothesis of the study was that microtopography is an integrating controlling factor of CH4 emissions and that isotopic composition of the emitted CH4 would reflect the processes beneath the peat surface. Also, it was expected that at the fen there would be more acetate fermentation which would show in the isotope results. Gas samples of emitted CH4 were drawn from hummocks, lawns and hollows using a closed chamber method to analyse CH4 flux and δ13CCH4. Pore water samples for DIC analysis were collected at the depth of 0.5 m to analyse δ13CDIC. In addition, water table levels and peat temperatures were measured at each sampled plot. All samples were collected once a month from May to August to identify changes during the growing period in 2015. The results revealed that the emissions of CH4 were the lowest from the hummocks at both sites, but the differences between fluxes from the hollows and lawns were less affected by microtopography. Water table levels and peat temperatures seem not to be the controlling factors for CH4 emissions. The isotopic composition of emitted CH4 was also mostly unaffected by microtopography. Only the hummocks at the bog had distinctively higher carbon isotope values compared to the other microsites. Unlike the CH4 flux results, the δ13CCH4 results depicted a seasonal trend during the growing period with all the microsites showing the most negative values in July. Combined to the results of the DIC analyses, it appears that the fen is characterized by more acetate fermentation, though the production pathway could not be identified unambiguously. The isotopic composition of emitted CH4 proved to be a suitable, but not sufficient application to differentiate CH4 production pathways, oxidation and transport. To better understand the processes beneath the peat surface and the effects of microtopography, CH4 flux and isotope data should be combined to multi-isotopic (CH4 and DIC) pore water samples drawn from multiple depths to demonstrate the vertical changes in the isotope composition at different layers of peat.

Tämän Pro Gradu –tutkielman tarkoituksena oli selvittää Euran Vaaniin pohjavesialueen rajojen muutostarve. Tutkimus oli osana laajempaa ympäristöministeriön ja maa –ja metsätalousministeriön hanketta, jonka tarkoituksena on luoda yhtenäinen ja selkeä ohjeistus hienoainespeitteisten akviferien pohjavesialueiden rajaamiselle. Kenttätyöt tehtiin kesällä 2011. Tutkimusmenetelminä olivat raekokoanalyysi kuiva- ja märkäseulonnalla ja hiukkasmittarilla, ionikromatografia, massaspektrometria, veden stabiilien isotooppien määritys ja rakennetulkinta. Tutkimusten perusteella Vaaniin pohjavesialueen nykyiset rajat eivät ole toimivia pohjaveden suojelun kannalta. Nykyisen pohjavesialueen ulkopuolisilta alueilta, joiden vedenjohtavuusarvot mahdollistavat pohjaveden muodostumisen, on hydraulinen yhteys harjuun. Vedenjohtavuusarvojen perusteella tutkimusalue voidaan jakaa kolmeen eri luokkaan, jotka ovat muodostumisalue (K > 10-6 ms-1), vettä osittain läpäisevä alue (10-7 < K < 10-6 ms-1) ja vettä läpäisemätön alue (K < 10-7 ms-1). Rakennetulkinnan perusteella hyvin vettä johtavat kerrokset ovat jatkuvia Vaaniin ja Euran keskustan välisellä osuudella. Harjun morfologia on vaihtelevaa eivätkä muutokset näy maanpinnalla aluilla, joilla harju on hienoainessedimenttien peittämä. Pohjaveden päävirtaussuunnat Kauttualta kohti Vaaniita ja jokilaakson reunoilta harjuun. Pohjaveden redox-oloissa tapahtuu muutos Mölsin alueen hapettavista oloista pelkistäviksi kohti Vaaniin vedenottamoa ja samanaikaisesti kemiallinen koostumus muuttuu jonkin verran. Veden stabiilien isotooppien perusteella pohjaveden osuus jokivedestä on noin 5 – 8 %. Vaaniin pohjavesialueen rajoja on tutkimusten perusteella syytä muuttaa. Ehdotetaan kahta muutosvaihtoehtoa. Ensimmäisessä pohjavesialueen rajoja siirretään itään ja länteen siten, että muodostumisalueeksi lukeutuvat moreenikumpareet ovat pohjavesialueella. Toisessa vaihtoehdossa pohjavesi- ja muodostumisalueiksi rajataan alueet, joiden vedenjohtavuusarvot mahdollistavat pohjaveden muodostumisen. Peitteisten akviferien pohjavesialueiden rajauksissa tulisi tutkimusten perusteella ottaa huomioon myös harjualueen ulkopuoliset alueet, joilta voi olla hydraulinen yhteys harjuun. Muodostumisalueen rajauksissa käytetään perusteena, että muodostumisalueeksi rajaan alue, jonka vedenjohtavuusarvo vastaa hienon hiekan vedenjohtavuutta tai on sitä suurempi. Tutkimusten perusteella määritelmää suositellaan muutettavaksi siten, että rajaksi otetaan vedenjohtavuusarvo 10-6 ms-1, koska se ei ota kantaa sedimentin laatuun.