| 1. |
- Pendrill, Florence, 1983
(författare)
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Felling Forests from Afar: Quantifying Deforestation Driven by Agricultural Expansion and International Trade
- 2019
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Deforestation is a major source of human-caused greenhouse gas emissions and the largest threat to terrestrial biodiversity. Most forest loss is due to the expansion of agricultural land use increasingly driven by international demand for food, fuel and fibre. However, there is still limited understanding of the extent to which different agricultural commodities are contributing to deforestation. It has therefore also been difficult to evaluate the role of international trade in driving deforestation. This dissertation aims at quantifying the agricultural drivers of tropical deforestation (Papers I and II) and the associated carbon emissions (Paper III). It further assesses the role of international trade, by following the agricultural commodities with embodied deforestation through international supply chains using trade models (Papers II and III). The results show that a few commodity types, primarily cattle meat and oilseed products, account for a large part of tropical deforestation. Much (26–39%) of the embodied deforestation and concomitant emissions were found to be associated with international demand (from products and services). Looking closer at the countries that import embodied deforestation, Paper II finds that many countries that are increasing their forest cover at home, import products associated with deforestation elsewhere, thereby offsetting about a third of their forest gains. Paper III finds that imports of embodied deforestation emissions for many developed countries are similar in size to their national agricultural emissions amounting, e.g., for the EU, to around 15% of the carbon footprint of an average diet. Put together, the results add to the evidence that combating deforestation can benefit from complementing domestic policies with measures that target international demand. The results also indicate that tackling deforestation and its associated impacts at the global level is probably even more challenging than at the national level, although international trade can also provide efficiency gains by optimising land use globally.
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| 2. |
- André, Hampus, 1989
(författare)
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Resource and Environmental Impacts of Resource-Efficiency Measures Applied to Electronic Products
- 2018
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Natural resources such as ecosystems, land, water and metals underpin the functioning of economies and human well-being, and are becoming increasingly scarce due to growth in population and affluence. Metals are increasingly demanded for their specific properties as modern technology develops. The dependence on metals is of growing concern due to the environmental impacts related, for example, to energy use and local impacts from mining, as well as the scarcity risks posed by socio-economic, geological and geopolitical constraints. Thus, there is a clear need to use metals and other natural resources more efficiently. The vision of a circular economy has been proposed as a way to do this, for example by improving durability, reusing, repairing and recycling. Such so-called resource-efficiency (RE) measures are commonly assumed to be environmentally beneficial, although the evidence is not plentiful. It is plausible that focusing on recirculating products and materials could shift burdens to other environmental impacts or life cycle stages. It has therefore been argued that a life cycle-based approach, such as in life cycle assessment (LCA), is useful to critically assess the environmental implications of RE measures. LCA aims to quantify the environmental impacts of products over their entire life cycles - from cradle to grave - assessing a wide range of impacts such as toxicity, climate change and metal resource use. For metal resource use, however, there are a number of perspectives as to what constitutes the actual environmental problem. These perspectives are represented in a variety of life cycle impact assessment methods (LCIA) which have previously been shown to give diverging results. Electronic products are emblematic of metal resource use challenges since they deploy a broad spectrum of scarce metals. This thesis aims to provide knowledge on the potential for RE measures to reduce the environmental impacts of electronic products, by addressing the following research questions: (1) What resource-efficiency measures result in reduced potential environmental impacts and resource use – for what types of products and under what conditions? (2) How does extended use of electronic products through design for increased technical lifetime, reuse and repair affect environmental impacts, particularly metal resource use? (3) How does the application of different LCIA methods for metal resource use influence interpretations of resource-efficiency measures applied to electronic products? This thesis builds on three appended papers which are all based on comparative assessments of resource efficiency, studied as resource use and environmental impacts per function delivered, using LCA and material flow analysis. The results indicate that extended use of electronic products through increasing technical lifetimes, reusing and repairing, is generally resource-efficient. Exceptions may occur, however, if extended use is insufficient to motivate impacts from producing more durable products or spare parts. Use extension of electronic products leads to resource efficiency in two distinct ways: through the intended use extension and by increasingly steering material flows into recycling. Further resource efficiency could be realised by combining RE measures over the entire life cycles of products. With regards to metal resource use, the choice of LCIA method can influence the interpretation of the results of RE measures for electronic products. Therefore, it is advisable to use several complementary LCIA methods to minimise the risks of overlooking potentially important resources issues. Furthermore, better understanding and transparency of such issues is valuable in order to provide more comprehensive information to decision-makers.
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| 3. |
- Khosravi, Maryam, 1975
(författare)
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Diurnal variation of stratospheric short-lived species
- 2012
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Diurnal variation of stratospheric short-lived speciesMaryam KhosraviChalmers University of TechnologyDepartment of Earth and Space SciencesAbstractThe depletion of ozone in the stratosphere has a direct impact on the amount of ultravioletradiation reaching the Earth’s surface. The ozone abundance and distributionis controlled by the photo-chemical reactions and catalytic cycles involving halogens(chlorine and bromine), odd hydrogen and odd nitrogen species as well as by atmospherictransport.An introduction to ozone related chemistry of the stratosphere and modelling ofshort-lived species using photo-chemical models is presented. A one dimensional (1D)atmospheric model is used in two distinct studies: modeling of short-lived species inthe Arctic lower stratosphere (paper I) and in the tropical mid to upper stratosphere(paper II).The first part of this thesis describes the diurnal variation of chlorine monoxide,ClO, which is the most important short-lived species controlling ozone in the polarlower stratosphere during winter and early-spring. The ClO-dimer cycle, involvingClO and its nighttime reservoir Cl2O2, contributes to about 75%of the polar ozone loss.ClO measurements from an airborne submillimeter radiometer in the Arctic twilighthave been compared with the results from a 1D photo-chemical model (MISU-1D), inorder to validate the model and to test the kinetics of the reactions controlling the partitioningof chlorine species during the course of a day. The results show that crosssections leading to faster photolysis rates of Cl2O2 match best with the ClO observations.This is consistent with the recent version of the chemical kinetics evaluation bythe Jet Propulsion Laboratory. Slower photolysis rates can not be reconciled with theobservations since active chlorine higher than the total available chlorine would be required.The model reproduces higher nighttime ClO than the observations, howeverthe nighttime ClOmodelled using recent JPL recommendations of the thermal equilibriumconstant agree within the uncertainty range of the observations. The sensitivityof the model to the assumed albedo and temperature are also tested. Neither the temperaturenor the albedo uncertainties allow us to reconcile the model with the lowerobserved nighttime ClO. Moreover, it is found that the ClO-BrO cycle decreases ClOmostly around sunrise and sunset.The second part of the thesis presents the partitioning and diurnal variation of chlorine,bromine, hydrogen, nitrogen and oxygen species in the tropics from the stratosphereto the lower mesosphere. Model results of the diurnal variation of HOCl (asone of the chlorine reservoirs), the related short-lived species ClO and HO2 and HCl(as the main chlorine reservoir) for the tropics and three altitudes (35, 45 and 55 km)are compared with measurements from five satellite instruments. The model resultsgenerally agree with the observations both in terms of the absolute values and the differencesbetween day and night.
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| 4. |
- Lee, Christina, 1992
(författare)
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A Life Cycle Approach to Environmental Sustainability in Aggregate Production Systems
- 2024
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Rock materials, such as sand, gravel, and crushed rock, serve as the foundation of our society. Known collectively as aggregates, these materials are essential for building foundations, concrete, and roads, making them the second most extracted material globally after water. Since these materials are often extracted directly from nature, responsible production is crucial to ensure long-term environmental sustainability. Meeting sustainability objectives requires comprehensive environmental reporting to fulfil Environmental, Social, and Governance (ESG) demands. In response to this need, Environmental Product Declarations (EPDs) have gained prominence in the construction sector. However, EPDs, based on Life Cycle Assessment (LCA), do not fully capture all relevant environmental aspects for aggregate extraction and production facilities, often referred to as quarries. This highlights the need for a holistic perspective when it comes to environmental management. EPDs can also cause challenges for producers who may face resource constraints, data collection difficulties, and limitations in environmental knowledge during the process of producing an EPD. Moreover, regarding EPDs solely as communication tools overlooks a value creation opportunity to identify environmental improvements in production systems. Therefore, integrating LCA with production simulations can enhance environmental management, necessitating the development of tools that simplify and support producers in this endeavour. This thesis proposes a tool structure based on the development work of an industry-specific EPD software tool, and explores its integration into environmental management practices for quarries, with the aim of improving environmental performance. By identifying potential industry-specific environmental impacts, the thesis highlights knowledge gaps and delineates the limitations of LCA tools when combined with production simulations aiming towards a more holistic perspective of environmental performance. Additionally, it offers recommendations for best practices in combining LCA tools into quarry environmental management to overcome limitations, and identifies key areas where industry improvements can be achieved.
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| 5. |
- Cai, Yiting, 1994
(författare)
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The impact of loading-induced stress variation on the seismicity of active faults
- 2023
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Surface loads such as the ocean, atmosphere, and continental water, constantly modify the stress field of the Earth’s crust. Most earthquakes occur at tectonic plate boundaries and such stress perturbations on the active faults at the plate boundaries may trigger earthquakes. Several previous studies reported that tides or hydrological loading could modulate seismicity in some areas. We elaborate on this idea and further investigate the accumulative effect of various loadings. In this work, we compute the total Coulomb stress change created by hydrological loading, atmospheric loading, and non-tidal ocean loading from 2011 to 2016 in the Kamchatka-Kuril Islands-Japan region, and then compare it to the background earthquakes in the same period. This thesis contributes to our understanding of the complex interactions between surface loading and induced seismicity, which has important implications for earthquake hazard assessment and risk mitigation.
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| 6. |
- Nylund, Amanda, 1989
(författare)
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Turbulent ship wakes and their spatiotemporal extent
- 2021
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Shipping activities occur in almost every part of the global oceans and in intensely trafficked shipping lanes there can be up to one ship passage every ten minutes. All these ships impact the marine environment in different ways through pollution or physical disturbance. This thesis is focused on the turbulent ship wake, a physical disturbance from ships and previously overlooked as an environmental impact. When a ship moves through water, the turbulence induced by the propeller and hull, will create a turbulent wake that remains and expands after the ship passage. The turbulence in the wake will govern the spread of contaminants and affect gas exchange in the wake water, physically perturb plankton, and potentially impact local biogeochemistry through increased vertical mixing. To be able to assess the environmental impact of ship-induced turbulence in areas with intense ship traffic, knowledge of the spatiotemporal extent and development of the turbulent wake is necessary. The aim of this thesis is to increase that knowledge, by conducting in situ observations of turbulent ship wakes, which can be used to estimate the spatiotemporal extent of the turbulent wake. By using a collection of methods, the thesis work has resulted in a first estimate of the spatiotemporal extent of the turbulent ship wake, based on more than 200 field observations of different real-size ships in natural conditions. The observed turbulent wakes showed large variation in their spatiotemporal extent, and further studies are needed to fully disentangle how environmental conditions and vessel specifications affect the intensity and extent of the turbulent wake. The results and experiences gained from the in situ observations, give an indication of the complexity entailed in characterising the development of the turbulent wake, and provide valuable input regarding the relevant parameters and spatiotemporal scales to include in future studies. The work of this thesis constitutes the first step in addressing the knowledge gap regarding the environmental impact of ship-induced turbulence and can be used as a road map for further studies within the field.
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| 7. |
- Diamantidis, Periklis, 1988
(författare)
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Exploring Strategies for the Combination of Multiple Space-geodetic Techniques
- 2020
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Space-geodetic techniques are based on signal acquisition from extraterrestrial radio sources that can be used to infer geodetic positioning and define Earth-fixed and inertial reference systems. These techniques, which include Very Long Baseline Interferometry (VLBI) and Global Navigation Satellite Systems (GNSS) among others, exhibit different strengths and weaknesses in recovering parameters of interest. VLBI, for example, has access to all parameters linking Earth-fixed and inertial reference systems, so-called Earth Orientation Parameters (EOP), while GNSS is superior at determining in one of the EOP, Polar Motion (PM), due to the ubiquity and global distribution of the GNSS network of permanent receivers. The combination of different space-geodetic techniques shows promise in suppressing technique-specific biases and determining parameters with greater precision. This thesis presents the principles of VLBI and GNSS, and then explores the different combination strategies that can be used in the aim of generating of high-quality space-geodetic products.
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| 8. |
- Acuña, José, 1982-
(författare)
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Improvements of U-pipe Borehole Heat Exchangers
- 2010
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The sales of Ground Source Heat Pumps in Sweden and many other countries are having a rapid growth in the last decade. Today, there are approximately 360 000 systems installed in Sweden, with a growing rate of about 30 000 installations per year. The most common way to exchange heat with the bedrock in ground source heat pump applications is circulating a secondary fluid through a Borehole Heat Exchanger (BHE), a closed loop in a vertical borehole. The fluid transports the heat from the ground to a certain heating and/or cooling application. A fluid with one degree higher or lower temperature coming out from the borehole may represent a 2-3% change in the COP of a heat pump system. It is therefore of great relevance to design cost effective and easy to install borehole heat exchangers. U-pipe BHEs consisting of two equal cylindrical pipes connected together at the borehole bottom have dominated the market for several years in spite of their relatively poor thermal performance and, still, there exist many uncertainties about how to optimize them. Although more efficient BHEs have been discussed for many years, the introduction of new designs has been practically lacking. However, the interest for innovation within this field is increasing nowadays and more effective methods for injecting or extracting heat into/from the ground (better BHEs) with smaller temperature differences between the heat secondary fluid and the surrounding bedrock must be suggested for introduction into the market.This report presents the analysis of several groundwater filled borehole heat exchangers, including standard and alternative U-pipe configurations (e.g. with spacers, grooves), as well as two coaxial designs. The study embraces measurements of borehole deviation, ground water flow, undisturbed ground temperature profile, secondary fluid and groundwater temperature variations in time, theoretical analyses with a FEM software, Distributed Thermal Response Test (DTRT), and pressure drop. Significant attention is devoted to distributed temperature measurements using optic fiber cables along the BHEs during heat extraction and heat injection from and to the ground.
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| 9. |
- Karlsson, Emma, 1980-
(författare)
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Organic geochemical investigation of sources, transport and fate of terrestrial organic matter in the southeast Laptev Sea
- 2012
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Permafrost carbon stores have been suggested to react to warming trends with increased terrestrial loading to its coastal waters. Presently, the warming has been seen to be especially high in the East Siberian Arctic and the fate of the major release of terrestrial matter to these coasts is yet to be detailed.Our work is focused on the East Siberian Shelf (ESS) – which is the largest continental shelf in the world. It receives substantial inputs of terrestrial organic matter both from the large Russian rivers and from eroding coastlines. The largest of its rivers, the Lena, discharges in Buor-Khaya Bay, which is also a hot spot for coastal erosion.Previous studies of molecular and δ¹3C and Δ¹⁴C composition of terrestrial organic matter received by Arctic coastal waters have suggested a different propensity of different terrestrial source materials towards bacterial degradation. This detailed isotopic and molecular marker survey which is the basis for this thesis reveals clearly distinguished source patterns both between surface water (POC) and sea floor (SOC) as well as with distance away from the sources. The heavy terrestrial dominance over marine/planktonic sources are clearly detected in gradients of high POC and SOC levels, as well as depleted δ13C -OC and high HMW/LMW n-alkane ratios. Furthermore, data suggests that terr-OC was substantially older yet less degraded in the surface sediment than in the surface waters. This unusual vertical degradation trend was only recently found also for the coastal and central East Siberian Sea. It seems that the riverine terr-OC component comprising mainly annual thaw layer surface soil dominates the buoyant surface water POC and is readily degraded. This is in contrast to the coastline-erosion terr-OC which is associated with minerals and therefore ballasted to the sediments where it makes up the key OC component and seems relatively protected from degradation.The study area of this work is a region with strong terrestrial influence hosting many of the important carbon cycling processes, and data reveal two important OC contributors of different origin, mineral associated coastal erosion matter and riverine borne surface soil matter. These two components may well represent different propensities to contribute to a positive feedback to climate warming by converting OC from coastal and inland permafrost into CO₂.
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| 10. |
- Sommer, Christian
(författare)
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Processes and factors governing benthic community dynamics—environmental change in the Baltic Sea
- 2019
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- As drivers of biogeochemical cycles and nutrient recycling, such as carbon turnover, the microbial community is essential in sustaining functioning ecosystems. Together with the metazoan community, the microbial community constitute the majority of all life in the benthos. Environmental change in biotic and abiotic factors may influence the dynamics of these communities, for example through a sorting or driving effect on the community structure through assembly processes. Environmental change, e.g. change in dissolved oxygen concentration, salinity and temperature, can directly or indirectly affect community composition. How, in what way, and to what extent, benthic bacterial and meiofaunal community composition in the eutrophied, brackish benthic environments, in the Baltic Sea sub-basin the Baltic Proper, respond to environmental change is understudied, both at local and seascape scale. This thesis aimed to study and understand the effects of environmental variation on the diversity and biogeographic patterns of Baltic Sea sediment bacterial and meiofaunal communities. A further aim was to understand the links between the different community levels by studying the interaction between meiofaunal- and macrofaunal communities in relation to environmental variation. Community diversity was analysed along a latitudinal transect of national environmental monitoring stations in the Baltic Proper using a framework of metapopulation and metacommunity theory. The analyses were based on environmental genomics, with high-throughput sequencing, bioinformaticsand statistics. The total community genome was analysed using phylogenetic marker gene fragments as a proxy for taxonomic diversity, to investigate diversity, community structure and dynamics. Salinity and oxygen were found to be the main abiotic environmental drivers of benthic community composition and alpha- and beta-diversity patterns. Furthermore, macrofauna-meiofauna interactions were significantly more complex in higher salinity environments. Results also showed that both enhanced environmental gradients and dispersal following a major inflow of saline and oxygenated water from the Atlantic Ocean, influenced the composition of sediment bacterial communities at the seascape scale of the Baltic Sea, as shown by a reduced beta-diversity and increased alpha-diversity, and the development of a significant distance-decay of community similarity. This study also identified strong metapopulation dynamics of the benthic sediment bacterial communities with many satellite and a few core taxa. The outcomes from this study contribute to the understanding of how environmental variation and environmental change relate to changes in Baltic Sea benthic community diversity and composition, and important factors and processes governing community dynamics.
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