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  • 1.
    Andrén, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Science.
    Development of the Laitaure Delta, Swedish Lappland: A Study of Growth, Distributary Forms and Processes1994Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Deltaic processes were studied on the Laitaure delta. Specific aims were to: analyse forms and processes in distributaries with regard to hydraulic geometry relationships; investigate the distribution of water into different distributaries; analyse the morphological development of the delta; and quantify the advance of the delta front. Further, a brief study was made of the bottom sediments in Lake Laitaure.

    It was concluded that distributaries may be distinguished by at-a-station hydraulic geometry relationships, depending on their state of activity and their location in the delta, i.e. distance to the delta front.

    Differences in activity between distributaries were also shown by the “delta” (analogous to downstream) hydraulic geometry relationships. Large similarities in “delta” hydraulic geometry were found between the Laitaure delta and the Volga and Danube deltas (cf. Mikhailov, 1970).

    It was found that the discharge in a distributary is linearly related to the total discharge in Rapaälven, and that the main distributary system may, inter alia, be distinguished from the other systems by its: (1) higher rate of increase in discharge with total discharge;  (2) decreasing proportion of the total discharge as this increases. Threshold discharges, i.e. the total water discharge in Rapaälven below which a channel has zero discharge, were determined for the “secondary” distributaries.

    The temporal variation in flow distribution is indicated by, for example, changes in the rate of deltaic advance at different mouths and aggradation of channel beds within distributary systems that have experienced reduced flows. It is concluded that the flow distribution is an important factor to be considered in studies of river deltas.

    The delta is growing by about 0.38 km2/year, equivalent to an advance of the delta front by approx. 4.5 m/year. Disintegration of vegetation is abundant all over the delta except for the distal parts. However, the proportion of delta lake area has decreased and the proportion of vegetated area has increased due to miniature delta formation, and deltaic growth.

    X-ray radiographs of sediment cores sampled in different parts of Laitaure, reveal annually laminated deposits, for which the variations in temporal and spatial sedimentation rates were investigated.

  • 2.
    Cajas, Margarita
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Science.
    Genesis and Diagenesis of the Phosphatic Hardground of the Holm Dal Formation (Late Middle Cambrian), North Greenland1997Licentiate thesis, monograph (Other academic)
    Abstract [en]

    The phosphatic hardground of the Holm Dal Formation (late Middle Cambrian) of North Greenland is composed of two parts: one basal with abundant allochthonous material and an upper part without an allochthonous component. It was formed by release of phosphate, by bacterial degradation, from organic matter which accumulated in lime mudstones on which the hardground developed.

    Following its release to pore water, the phosphate precipitated as apatite forming the hardground, in which cyanobacterial assemblages fossilized. Echinoderm holdfasts are a conspicuous feature of the hardground.

    REE analysis and the well preserved cyanobacterial fossils point towards an early diagenesis. The same REE analysis and the existence of bitumen in the samples, indicate dysaerobic conditions during the formation of the hardground.

    Isotopes analysis (143Nd and 144Nd) underline the marine biogenic character of the apatite.

  • 3.
    Edström, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Science.
    Syre-18-halt hos markvatten extraherat genom centrifugering och destillering av jordprover1993Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In hydrological studies it is often necessary to know the flow pathways and residence time of soil water. The oxygen isotope 18O can be used as a conservative hydrological tracer to help determine water´s movement. To extract soil water from soil samples for 18O analysis, a distillation method is often used. An easier and faster method for extracting soil water is high speed centrifugation. All soil water, however, is not extracted from a soil sample by this method. It is therefore possible that the water extracted by centrifugation does not have an 18O content that is representative of the soil water. In this study, the 18O values of water extracted by distillation and centrifugation are compared. Soil water was extracted from undisturbed soil samples and from oven-dried soil samples saturated with water of a known 18O content. The extractions were done both by centrifugation at different speeds followed by distillation and by distillation only. All of the samples were then oven-dried. The differences in 18O content between water extracted by centrifugation at different speeds were small. The 18O content in the water extracted by distillation was, with one exception, more depleted in 18O than the water extracted by centrifugation. From the oven-drying it was seen that the distillations did not succeed in extracting all soil water. This might be a reason for the depletion in 18O content of the water extracted by distillation. Due to incomplete distillation, this study was not able to determine how well the 18O content in water extracted by centrifugation represents the water bound most strongly to the soil. For characterizing the 18O content in the least bound soil water, however, centrifugation is not only faster, but also less prone to error than distillation.

  • 4.
    Ekblom, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Science.
    Syrgastäring, fosforläckage och bakteriehalt i sediment från Stockholms innerskärgård1995Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    During autumn 1994 an investigation-sequence was started by Stockholm Vatten AB where oxygen demand and PO4-P-leakage were analysed of sediments from few lakes in the drainage area of Stockholm. As a contribution to the investigation-sequence the oxygen demand and the PO4-P-leakage of homogenised sediments at 13 locations in the archipelago of Stockholm were analysed during spring 1995 in this report, using a new method. Parallel to these analyses there was a test of the reproducibility of the analysis-device, determination of bacterial biomass and potential activity of denitrified bacteria in sediments from each sample location. The results indicate that the oxygen demand is dependent on type of the bottom the sample were taken and on the organic content of the sediments. The magnitude of the PO4-P-leakage seems also to be dependent on the type of the bottom as well as the physical conditions that characterise the location. The reproducibility of the new analysis-device seems to be relatively good for measurements of both O2- and PO4-P-concentrations in water above the sediments. The coefficient of variation was low at O2-saturation where the oxygen demand were measured, i.e. O2-saturation ≥50%. In the same manner, the coefficient of variation was low at PO4-P-concentrations above 100 µg/l. The bacterial biomass varied between 0,48 and 2,66 mg/g DS, with the lowest concentrations in the inner parts of the test-area and the highest concentrations in the outer. The result of the potential activity of denitrified bacteria showed an irregular pattern in the test-area.

  • 5.
    Göransson, Elisabet
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Science.
    Organiska horisontens kemi som en indikator på in- och utströmningsförhållanden i skogsmark1995Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A thorough understanding of soil water and groundwater flow is necessary to understand the transport of elements in forest soils. The National Forest Soil and Vegetation Survey has no possibilities to determine groundwater flow using total potential measurements in the sampling plots. In the present work an alternative approach using soil chemistry to classify the extent of recharge and discharge conditions in the sampling plots was used. A multivariate model was created to classify groundwater regime in a forested hillslope south of Tärnsjö in the northern part of Uppland, Sweden. The model was based on principal component analysis (PCA) of different variables in solid organic matter in the organic horizon in the soil. The chemical variables used were pH(H2O), pH(BaCl2), total C, N and S in organic matter, the percentage of Al3+, H+, Ca2+, Mg2+, K+, Na+ in the exchange complex, the effective CEC and the percentage of organic matter in the soil samples. PCA indicated that; (1) samples from the recharge area were characterised by low pH, low Na+ and relatively high K+ levels, (2) the unsaturated discharge zone was characterised by high levels of exchangeable Al3+ and (3) the nearly saturated discharge area was characterised by high Na+, Ca2+ and Mg2+ levels, higher pH and higher amounts of N and S in the organic matter. This study indicated that groundwater regime in a forested hillslope is of major importance in determining the chemical status of the organic matter in the organic horizon. It was possible to use information obtained from soil chemical analysis to determine the extent of recharge or discharge at the points where the soil samples were taken. The PCA model used in this work gives guidelines for the construction of a general model for classification of groundwater regimes.

  • 6.
    Jaedicke, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Science.
    Lake Evaporation Estimation by Isotope, Energy Balance and Bulk Aerodynamic Methods1997Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Lake evaporation from a shallow lake in central Sweden has been estimated using three independent methods from measurements during summer 1995. The applied isotope method is a combination of the water and isotope mass balance. Its main feature is that inflows need not to be measured. Only knowledge of their isotopic content is sufficient. For calculations by the bulk aerodynamic method a computer program was applied, which takes into account the different conditions of stratification. The energy balance of the lake was determined by using the short and long wave radiation, heat storage and advective heat energy. Measurements were done on a small island and at a mast in the middle of the lake. Evaporation estimated by all the methods varied from -1.1 to 5.0 mm/d during the summer months 1995. Values estimated by the energy balance method agreed well with those from the bulk aerodynamic method. Evaporation estimates from the isotope method a showed fairly good agreement with the two other methods, excepting a few periods. It was found that both the isotope as well as the energy balance method are sensitive to errors in lake volume. Both methods carry some uncertainty due to their dependence on water balance components, some of which are difficult to determine. The bulk aerodynamic method is independent of the water balance of the lake. A good accuracy can be achieved using only four variables i.e. wind speed, relative humidity, skin and air temperature.

  • 7.
    Kjerrström, Jessica
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Science.
    Grundvattennivåns samband med lufttemperatur och nederbörd i Sverige1997Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Faced with possible climatic changes and a possible greenhouse effect the importance to study the connection between climate and groundwater level grows. The hypothesis that the groundwater level in Sweden has a climatic connection regarding precipitation and air temperature was therefore tested. Groundwater stations, mainly situated either in gravel or sand and choosen from "Grundvattennätet", was divided into classes based on their patterns of variation over time. The groundwater levels were studied regarding trends. The hypothesis was tested in two steps. First statistically through linear correlation for the whole year, summer and winter season in nine areas in order to prove the existence of a connection. Next simulations with HBV light were made in order to show if a possible connection could be explained on physical basis. The result in the statistical analysis showed on a connection between groundwater level and temperature respectively precipitation where the temperature connection was weaker. Model simulations using HBV light showed a physical connection between groundwater level and climate.

  • 8.
    Lindahl, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Science.
    Modellering av avdunstning utgående från markfuktighetsmätningar i moränmark1996Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A one-dimensional SVAT-model (Soil-Vegetation-Atmosphere) was used to simulate evaporation and estimate the critical soil water potential where the reduction of the water uptake begins. This was done in a mixed pine and spruce forest in the north of Uppland, Sweden for the period 1 May to 31 October 1994. This period was unusually warm and dry and gave a unique chance to study the water uptake and the drought. Driving variables to the model were daily meteorological data and soil physical properties. The model was calibrated with TDR- (Time-Domain Reflectometry), tensiometer and ground water level measurements from the site for the same period. The critical water potential was estimated to -100 hPa and appeared to be a sensitive parameter in the model. The reduction of the water uptake began at the end of June. The surface resistance was calculated from the leaf area index and the Lohammar equation. The soil physical properties were shown to be significantly affecting the results of the simulation. The determination of these properties was uncertain because of the problems to measure in an inhomogenous till soil. The model simulations agreed generally well with the soil moisture measurements in some layers but a good agreement for all layers was not possible to obtain.

  • 9.
    Ljungberg, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Science.
    Evaluation of stimulated reductivedechlorination in situ of chlorinatedsolvents at a site in Huddinge: using principal component analysis, partialleast square regression and degradation2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The method of using stimulated reductive dechlorination when remediating sites contaminated with chlorinated solvents is not unusual, but not many studies have been done on the overall process outside of a controlled environment. In order to investigate the process, principal component analysis (PCA) and partial least square (PLS) regression was used to identify the most important parameters for the degradation of the chlorinated solvents. The most important parameter for all chlorinated compounds turned out to be oxygen, with levels of degradation products increasing with decreasing levels of dissolved oxygen. Dissolved oxygen was deemed the most important variable to measure during a control program on the site.

    The degradation dynamics of the process were investigated to examine the behaviour of the chlorinated solvents and their degradation products. The degradation products of the main contaminant TCE were found in all observation points, which indicates an ongoing reductive dechlorination all over the site. A large amount of the mother product, TCE, was found in two observation points, which were believed to be situated close to the sources of the TCE contamination. Over the observation period of 2,5 years the levels of TCE in the source areas decreased significantly to below the remediation goal. However, the levels of TCE increased in another observation point further downstream, with concentrations still increasing at the end of this study. The levels in this point were lower than those measured initially in the source area, but still much higher than the accepted values. Possible reasons for this appearance of TCE could be an isolated sheet of contaminants being pushed into the observation point from a nearby location or transport of the contaminants from the source area in units of higher conductivity such as sand lenses or fractures in the clayey soil.

  • 10.
    Möne, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Science.
    Glacial lake deposits in Kerlingarfjöll, Central Iceland1997Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The extent of glacial lake sediments found north of the Kerlingarfjöll mountains in central Iceland has been determined and their formation in an ice dammed lake is suggested. The damming ice moved from an ice divide in the south-east highlands and was divided into two ice lobes by the Kerlingarfjöll mountains. In an early stage the lake was dammed between the two ice lobes but as they retreated the glacial lake was enlarged in the eastern part where it in the later stage was dammed by topography. The ice dammed lake was almost filled with sediments before it drained to the west when the western ice lobe retreated. The ice dammed lake was contemporaneous with the Hvítárvatn ice dammed lake which was dammed between the western ice lobe and the hills below the Langjökull glacier.

  • 11.
    Nyberg, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Science.
    Adsorption av cesium på krossad granit - en faktor inför slutförvaret av kärnbränsle1997Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Over the last few years, a model that simulates the transport of radionuclides in fractured rock has been developed at the Department of Earth Sciences/Sedimentology, Uppsala University, Sweden. The aim has been to predict the outcome of a possible leak from deposits of nuclear waste fuel in deep bedrock. The adsorption of cesium ions at the fractures is an important part of the transport mechanism. This study has attempted to explore the adsorption kinetics of cesium ions at the surface of granite particles. A certain amount of cesium was mixed with synthetic groundwater along with different fractions and amounts of clean granite particles. The concentration of cesium in the liquid was frequently measured in order to estimate the change in cesium adsorption with time. The measurements were carried out until an equilibrium between adsorbed and solute ions was achieved. Depending on the size of the particles, the adsorption was characterized by either a one- or a two step kinetics. The reason for this was that larger particles contain micro fractures which affect the adsorption curve. The results were evaluated from the estimated values of the distribution coefficient kd and the reactivity coefficient kr. A model that evaluates the available surface of the rock gave very good results for the kd-values with a R2-value above 0.99. The fitting of kr was not by near equally good (R2 ≈ 0.36), and this is assumed to depend on an incorrect expression of the net adsorption G.

  • 12.
    Persson, Karl
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Science.
    Vattenkraftsmagasins påverkan på koltransporten; simulering av kolbudget och mätning av sjösediment i Tjaktjajaure1997Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The climatic delegation of the Swedish Parliament gave in 1996 Vattenfall Utveckling AB the mission to examine the Swedish hydroelectric-powers influence on global warming. The reason for this were science reports which had indicated that hydroelectric plants in some cases are significant sources for generating greenhouse gases. A work to examine the carbon transport in the Luleå river has therefore been initiated. This report is a start-up of the work and here one of Sweden´s largest hydroelectric plants (Tjaktjajaure) is to be studied. The research has been done through construction of a computer model for simulation of the carbon budget and measurement of the lake sediment. The point of this project was meant to find the dynamics of the system with the model and that has shown to be possible. It was observed that the relation between different lake-bottom types did not change if model constants varied. Sensitivity analysis indicated that no conclusions of the size magnitude of the processes could be made in the model without further studies. Small variations in model constants resulted in large variations in gas transport and sedimentation. The sediment measurement was meant to show the size magnitude of carbon sedimentation. Cesium analysis were used to date the sediment; and analysis of water content and loss on ignition were used to calculate the content of carbon in the sediment. However, the dating method did not work out well, and that is why the size magnitude of sedimentation could not be found. The content of carbon in the sediment was relatively constant in the lake, between 100 and 150 g/ m2cm. It was also observed that the lake had small areas with soft sediments, but these areas contained a large magnitude of material.

  • 13.
    Widén, Britta
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Science.
    Nitrification and denitrification in seagrass communities in Chwaka bay, Zanzibar1996Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As a response to the environmental degradation of many coastal areas in east Africa research have been initiated aiming towards the understanding of the coastal ecosystems and the interactions between them. The sediment of three seagrass communities were investigated with regard to nitrification, denitrification, pore water nutrient content, organic content and physical character. The aim was to estimate the magnitude and importance of nitrification and denitrification and correlate those to any difference in organic load. Total organic carbon and total nitrogen decreased while C:N ratio increased with distance from the mangroves indicating a larger organic load closer to the mangroves. There was however no significant difference between the sites regarding ammonium and nitrate + nitrite concentrations in the porewater; nor regarding denitrification. Recalculated to ambient nitrate concentrations denitrification was less than 157 nmol N m-2h-1. No trend could be seen for nitrification either. Nitrification ranged from 0-12.0 µmol N m-2h-1, but the method used may underestimate the rates. Denitrification, and especially nitrification rates, varied considerably within each site indicating an extremely patchy environment. Considering that nutrient regeneration rates in tropical environments are usually high, nitrification and denitrification seemed to be minor pathways in the nitrogen cycle irrespective of organic load. The study also suggests that nitrification and denitrification may be of less importance in Chwaka bay compared to other areas studied.

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