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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 53 for “"chemical weathering"”.
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Chemical weathering of sulfide mineralization on Mars
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1990.
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Forsterite Dissolution Kinetics: Applications and Implications for Chemical Weathering
… earth's crust so it is not surprising that their weathering reactions dominate the chemistry of many earth surface processes. This project used forsterite as a model system to identify the important factors that affect silicate mineral dissolution rates and grain lifetimes in the weathering …
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Chemical Weathering History of Antarctica During A Late Eocene Glacial Event
… temperature, ice sheet growth, and continental weathering analyzed from ODP Site 738 sediments off the coast of East Antarctica have offered insight into the variable climate of the Paleogene 'greenhouse.' In this study, I compile evidence from fine fraction carbonate, benthic foraminifera, …
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Meteoric 10Be as a Tracer for Subglacial Chemical Weathering in East Antarctica
Subglacial chemical processes in Antarctica are potentially significant contributors to global geochemical cycles, but current understanding of their scale and nature is limited. A sequential chemical extraction procedure was developed and tested to investigate the utility of meteoric 10Be as a …
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Stable isotope and trace element fractionation and implications for chemical weathering rates
The student, Nicole Fernandez-Franzan, accepted the attached license on 2020-05-05 at 04:05.
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Catchment Structure Regulates Hydrodynamic Drivers of Chemical Weathering in Shallow Forest Soils
… and soil solution acidity are known to influence weathering rates and soil transformation processes, an integrated understanding of these factors together is still lacking. This dissertation explores the effects of subsurface flow on the mobility and distribution of dissolved organic carbon (DOC) …
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Linkages between fluid flow paths, reactive gases, and chemical weathering across a shale bedrock hillslope
… we report an integrated approach to characterize chemical weathering reactions in the vadose zone using a novel Vadose Monitoring System (VMS) installed at the Eel River CZO in combination with laboratory experiments and reactive transport modeling. The VMS allows for the direct observation of …
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The Carbon Budget of the Mekong River Basin: A Spatial and Temporal Study of Chemical Weathering
The chemical weathering of silicate rocks with carbonic acid is thought to play an important role in the consumption of atmospheric carbon dioxide (CO$_{2}$), which regulates global climate over million--year timescales. However, the climatic implications of chemical weathering of carbonate rocks …
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Weathering Regimes and Pedogenic Variability on Large Boulders, Karkevagge, Northern Scandinavia
… of the secondary clay minerals indicating that chemical weathering was occurring; (6) The soil-rock interface is presumed to be the location where most of the chemical activity concentrates, which when combined with the effects of schistocity indicates that microvariability and microenvironment …
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Oxidation of Microplastics: Evidenced by Spectroscopy, Hydrophilicity, and Heavy Metal Uptake
<p>Two weathering methods of pristine microplastics have been studied and compared to determine the best combination for the desired weathering results, chemical versus irradiation. The chemical weathering was studied using various temperatures, pH values and contact time. Irradiation studies were …
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Adsorption–Desorption Reactions in the Weathering Zone: Implications for Silicate Weathering & the Carbon Cycle
The carbonic acid-driven chemical weathering of silicate minerals removes carbon dioxide (CO2) from Earth's atmosphere. The tectonic processes of uplift, exhumation, and erosion modulate the negative feedback relationship between climate, silicate weathering rates, and atmospheric CO2 removal rates …
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Sediment chemistry as an archive of provenance and weathering in the Mekong River Basin
The chemical weathering of rocks, in particular silicate weathering, has been proposed to be an important natural carbon-removal process that regulates the Earth’s climate over millions of years. Tectonically active regions, such as the sub-Himalayan region, are considered a hotspot of silicate …
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A spatial and temporal study of the carbon cycle; the role of carbonates in buffering Earth’s climate
… between volcanic degassing rates and silicate weathering. To force environmental changes in this way, such as the CO<sub>2</sub> decline observed during the Cenozoic Period (66 Myr - present), requires either a decrease in volcanic degassing, or an increase in silicate weathering and a change …
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Investigating potential climatic cycles in glacially-influenced rhythmites of the upper Gowganda Formation using geochemical, sedimentological and spectral analyses
… rhythmites have undergone limited recycling and chemical alteration. Whole-rock δ18O values are consistent with an Archean gneiss provenance and support that chemical weathering and diagenesis were insignificant. Spectral analysis of four rhythmic couplet thickness records using the MTM Toolkit …
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RECENT RIVERINE CARBON OF THE YELLOW RIVER: FLUXES, OUTGASSING AND BURIAL
… and quantitatively investigated. Due to chemical weathering occurring in the basin, 0.628 Mt of atmospheric CO2 is consumed annually. In addition, the Yellow River basin as a whole acts as a carbon source for the atmosphere. Approximately, 1.05-4.19 Mt of CO2 is emitted into the …
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Hillslope erosion and weathering rates in Earth's most rapidly uplifting mountains
… the degree to which mountains regulate biogeochemical cycles and global climate. Landslide erosion and soil production are the principle denudation processes in high-relief terrain, but quantitative estimates of landslide erosion on spatial and temporal scales relevant to landscape evolution …
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Stratigraphy and sedimentology of the Tongue River formation (Paleocene), southeast Golden Valley County, North Dakota
… characteristics of both members indicate little chemical weathering, a short distance of transportation, and little reworking. Heavy minerals are indicative of a metamorphic source area with associated granites.</p> <p>The fauna and flora of plants, fish, reptiles, amphibians, gastropods, and …
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Distribution of hydrocarbons in a salt marsh ecosystem after an oil spill and physiological changes in marsh animals from the polluted environment
… the oil in the marsh ecosystem, 3) on changes in chemical composition of the oil with time due to physical and chemical weathering processes and biochemical degradation of hydrocarbons, 4) on the effects of oiled sediments on the population distribution, behavior, and survival of the intertidal …
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Soil weathering under mountain pine beetle killed trees, Grand County, Colorado
… of this study is to assess differences in soil weathering processes under mountain pine beetle killed trees, as compared to soil weathering under living trees. As pine beetle (Dendroctonus pondersoae) infected trees die, pine needles are shed and accumulate on the forest floor, which may lead to …
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Assessing landscape and seasonal controls on CO2 fluxes in a karst sinkhole
… and suggest that subsurface processes such as chemical weathering and cave ventilation affect the direction and magnitude of CO2 fluxes.
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