Sökning: "NATURAL SCIENCES Earth sciences Other earth sciences"
Visar resultat 26 - 30 av 2992 avhandlingar innehållade orden NATURAL SCIENCES Earth sciences Other earth sciences.
26. Mixture toxicity of pesticides and biological effects in agricultural streams : field and laboratory studies
Sammanfattning : The main objective of this thesis was to examine pesticide mixture toxicity and its effects on aquatic biota in agricultural streams. This was accomplished by (1) calculating the ΣTUs for algae and Daphnia magna and a pesticide toxicity index (PTI) based on water quality standards (WQS) for long-term monitoring data (2002-2010), (2) by performing algal inhibition tests with Pseudokirchneriella subcapitata, using both collected in situ water samples and reconstituted water spiked with field-observed pesticide mixtures, and (3) by studying seasonal changes in macroinvertebrate and diatom communities during 2008 in four agricultural streams and determine a set of community-based metrics such as species richness, diversity, ASPT, SPEAR and IPS. LÄS MER
27. Stewardship in an urban world : Civic engagement and human–nature relations in the Anthropocene
Sammanfattning : Never before have humans wielded a greater ability to alter and disrupt planetary processes. Our impact is becoming so noticeable that a new geological epoch has been proposed – the Anthropocene – in which Earth systems might no longer maintain the stable and predictable conditions of the past 12 millennia. LÄS MER
28. Freshwater methane and carbon dioxide fluxes : Spatio-temporal variability and an integrated assessment of lake and stream emissions in a catchment
Sammanfattning : Freshwater bodies such as lakes and streams release the greenhouse gases methane (CH4) and carbon dioxide (CO2) into the atmosphere. Global freshwater CH4 and CO2 emissions have been estimated to be of a similar magnitude to the global land or ocean carbon sink, and are thus significant components of global carbon budgets. LÄS MER
29. Origin of organic compounds in fluids from ultramafic-hosted hydrothermal vents of the Mid-Atlantic Ridge
Sammanfattning : Natural gas, primarily methane (CH4), is produced in substantial amounts in ultramafic-hosted hydrothermal systems. These systems could also generate oil (heavier hydrocarbons) and the first building blocks of life (prebiotic molecules). In the presence of iron bearing minerals, serpentinisation reactions generate H2. LÄS MER
30. Coal and Oil: The Dark Monarchs of Global Energy : Understanding Supply and Extraction Patterns and their Importance for Future Production
Sammanfattning : The formation of modern society has been dominated by coal and oil, and together these two fossil fuels account for nearly two thirds of all primary energy used by mankind. This makes future production a key question for future social development and this thesis attempts to answer whether it is possible to rely on an assumption of ever increasing production of coal and oil. LÄS MER
