Browsing by Subject "stabiilit isotoopit"
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(2020)Artificial groundwater is produced in Jäniksenlinna water treatment facility in Tuusula by infiltrating surface water from the lake Päijänne to the Jäniksenlinna aquifer. The geochemical properties of the artificial groundwater vary and challenge the water purification process in the Jäniksenlinna facility. The objective of the study was to solve the geochemical quality of the water in different locations inside the aquifer area and in the different steps of the water purification process and to solve the changes in the geochemistry of the water caused by the seasonal changes. The study was put into effect by collecting 20 water samples, 16 of which were from different locations inside the aquifer area and 4 of which were from the different steps of the water purification process in the water plant. The samples were collected during the spring 2018 and repeated during the summer 2018. Each water sample was analyzed for major ions by ion chromatography, trace elements by ICP-MS method and stable isotopes of hydrogen and oxygen with the help of Picarro device. Additionally, each sample was analyzed in the field for electric conductivity, pH and temperature and in laboratory for alkalinity, pH and electric conductivity. The results from the spring and from the summer were handled separately since they differed with statistically significant levels from each other. The results were treated with statistical methods and visualized with tables, graphs, photos from the sampling points and maps. The results show that season changed the proportion of the natural and the artificial groundwater in the sampling points. However the season had no effect on the existence of the artificial groundwater in the sampling points. The proportion of the artificial groundwater was highest while the groundwater level was low, that is during the summer. The sampling points were selected with different distances to the infiltration area. However, the amount of infiltrated water did not decrease with the growing distance to the infiltration area, since the geological structures of the aquifer define the water flow inside the aquifer. The amount of artificial groundwater was lower in one sampling point closer to the infiltration area than in two sampling points further away the infiltration area. The water purification process removes the excess iron and manganese from the artificial groundwater and produces water which fulfills the standards set for the drinking water. The amount of iron and manganese in the drinking water might get even lower by conducting the water from the well 12 to the iron and manganese removal. The study covered the spring and the summer seasons, but in order to study the whole annual picture, the sampling should cover the autumn and the winter seasons as well. Flow modelling could give better picture of the formation of the artificial groundwater in Jäniksenlinna.
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(2024)In this thesis, fossilized teeth of herbivores from four sites in Western Mongolia (Altanteel, Chono-Kharyakh, Oshin-Boro-Udzyur-Ula and Khrigis Nur) are examined for their stable carbon and oxygen isotope record. The fossils date to the Late Neogene period (ca. 10-3 Ma). The aim of the thesis is to reconstruct the palaeoclimate and palaeoenvironment of Western Mongolia during the Late Neogene using the isotopic records obtained from the fossilized teeth. The enamel of fourteen teeth from Rhinoceros, Equids, and a possible Giraffid was sampled and analyzed for δ13C and δ18O-values. The analyses were conducted using well-established methods with Isotope Ratio Mass Spectrometry. The stable carbon isotopes (13C and 12C) can be used to determine, the types of plants that these animals consume. Plants can be categorized into three groups based on their photosynthesis pathways. This study focuses on the C3 -plants, typically found in moister environments, and the C4-plants, which thrive in dry conditions. Specific δ13C-values have been established for these groups: –34‰ to –24‰ for C3-plants, and –20‰ to – 9‰ for C4. The δ13C-values obtained from the teeth of herbivores can be compared to these limits, allowing evaluation of the mammals’ diets (whether they consisted of C3 or C4-plants). If C3 plants dominate the die, this would indicate a moister climate, and likely a forested environment. Conversely, the presence of C4 plants would suggest grassland areas with more arid climatic conditions. The stable oxygen record in the teeth relates to the δ18O-composition of meteoric water in the area. Analysing δ18O-values facilitates the reconstruction of the mean temperatures of the habitats and allows for a comparison of climatic factors affecting precipitation and temperature over time. The stable carbon and oxygen records are compared to reconstruct the climate and environment of Western Mongolia during the Late Neogene. The results suggest an increase in the δ13C-values over time, which indicating a shift in the animals’ diets towards a more drought-stressed C3 and C4 plant-based one. The δ18O-values, on the other hand, remain stable and do not indicate a change in temperature during the Late Neogene. Comparing both the δ13C- and δ18O- values with studies conducted in China indicates a gradual aridification in Western Mongolia and China during the Late Neogene. However, the temperatures did not change significantly, although there were most likely alternating cooler and warmer periods during the time span of 10-3 Ma.
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