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Articles 571 - 600 of 1549
Full-Text Articles in Earth Sciences
Petrogenesis Of Unusual Occurrence Of Amphibole Asbestos In Mohave County, Arizona And Clark County, Nevada, Tomoyo Austin
Petrogenesis Of Unusual Occurrence Of Amphibole Asbestos In Mohave County, Arizona And Clark County, Nevada, Tomoyo Austin
UNLV Theses, Dissertations, Professional Papers, and Capstones
The term “asbestos” applies to six types of fibrous amphiboles or chrysotile with specific morphologies that are commercially mined and processed. Inhaling asbestos fibers is known to cause many negative health effects, including mesothelioma, several different cancers, various respiratory diseases and non-respiratory diseases, and fatalities. The recent years, several cases of non-occupational exposure to asbestos fibers raised an awareness of environmental exposure to naturally occurring asbestos (NOA) which refers to asbestiform minerals that fall out of the regulatory definition of asbestos.
There are two sources of NOA in the area, Wilson Ridge pluton, AZ, and Boulder City pluton, NV which …
Geochemical Analysis Of Mississippian Cherts And Devonian-Mississippian Novaculites, Southern Midcontinent Region, Julie Mary Cains
Geochemical Analysis Of Mississippian Cherts And Devonian-Mississippian Novaculites, Southern Midcontinent Region, Julie Mary Cains
Graduate Theses and Dissertations
This study uses trace elements and radiogenic isotopes (Pb, Sr, and Nd) to investigate the origin and mode of formation for the siliceous deposits in the Lower Mississippian Boone Formation and the Devonian-Mississippian Arkansas Novaculite in the southern midcontinent. Mississippi Valley-type Pb-Zn ore deposits in the Tri-State District and the Northern Arkansas District were deposited by hydrothermal fluids, and highly radiogenic Pb isotope ratios suggest a genetic relationship between the Boone Formation chert (206Pb/204Pb ~ 21.59, 207Pb/204Pb ~ 15.87, 208Pb/204Pb ~ 40.10) and the MVT ores. Due to the very low concentration of Pb in the Boone chert (~2 ppm) …
Incorporating Recent Geochemical And Isotopic Constraints In Age Dating The Waters Of Hot Springs National Park, Arkansas, Kristina Marie Raley
Incorporating Recent Geochemical And Isotopic Constraints In Age Dating The Waters Of Hot Springs National Park, Arkansas, Kristina Marie Raley
Graduate Theses and Dissertations
Mean water age for spring discharge in Hot Springs National Park was calculated as approximately 4,400 years by Bedinger et al (1978) using carbon-14. Their analysis indicated that the water was a mixture of a small portion of cold water that was less than twenty years old with a preponderance of hot water. However, this result includes some error due to Bedinger et al. using general isotopic values for soil dissolved inorganic carbon and mineral carbon instead of obtaining actual values from the study area. A more accurate age calculation for the springs has been made possible by additional geological …
Protocol Implementation Plan For Cave Water Quality Monitoring In The Northern Great Plains Network, Narrative Version 1.0, Isabel W. Ashton, Justin S. Mills, Marc Ohms, Daniel Austin, Michael Wiles, Kara Paintner-Green
Protocol Implementation Plan For Cave Water Quality Monitoring In The Northern Great Plains Network, Narrative Version 1.0, Isabel W. Ashton, Justin S. Mills, Marc Ohms, Daniel Austin, Michael Wiles, Kara Paintner-Green
United States National Park Service: Publications
Executive Summary
The Northern Great Plains Inventory and Monitoring Network includes thirteen park units located in five northern Great Plains states across six ecoregions. Two park units, Jewel Cave National Monument (JECA) and Wind Cave National Park (WICA), protect significant cave resources. These two caves are among the longest caves in the world and have an assortment of underground water resources ranging from drip sites to cave lakes. Subsurface water quantity and quality in the caves is a concern due to groundwater depletion and groundwater contamination from pesticides (aboveground applications), hydrocarbons (vehicle use and related activities), and wastewater effluent (sewage …
Spatiotemporal Variation Of Benthic Silica Fluxes In The Ngom Shelf, Byron Ebner
Spatiotemporal Variation Of Benthic Silica Fluxes In The Ngom Shelf, Byron Ebner
LSU Master's Theses
Dissolved silica (DSi), plays an important role in regulating primary productivity of silicifying organisms, such as diatoms which precipitate hard parts composed of biogenic silica (bSi) in coastal and shelf ecosystems fed by major rivers. In the Northern Gulf of Mexico (NGOM), loading of nitrogen and phosphorous have increased compared to a decline in DSi in the Mississippi River. Continued decreasing in DSi loading could lead to limited diatom growth and production or shifts in community composition, therefore, it is important understand the role of benthic fluxes in providing silica to the overlying water column as there are few regional …
Nitrogen And Phosphorus Uptake In An Urban Stream Ecosystem, Nicolette A. Sheffield
Nitrogen And Phosphorus Uptake In An Urban Stream Ecosystem, Nicolette A. Sheffield
Theses and Dissertations
Urban stream ecosystems are faced with high input levels of nitrogen (N) and phosphorus (P) from anthropogenic activities. N and P are important to plant growth and stream health; however, high levels can lead to algal blooms and eutrophication, a harmful effect to both aquatic life and water quality. Common urban sources of N and P include fertilizer, atmospheric deposition, stormwater outfall, and leaf-litter decomposition. Common urban stream features such as a flashier hydrograph, altered channel stability and morphology, increase in nutrient output (such as N and P), and heat retention, have been shown to result in an overall decrease …
Living In The World Of Manmade Chemicals: Lessons Learned From The Migrations And Collapses Of Civilizations, Satish Myneni
Living In The World Of Manmade Chemicals: Lessons Learned From The Migrations And Collapses Of Civilizations, Satish Myneni
Sustainability Seminar Series
Many of the world’s natural surface and groundwater resources are getting contaminated with an increasing number of manmade chemicals, which include farm and household insecticides, industrial pollutants, and pharmaceuticals. As the sizes of potable water bodies are decreasing steeply, it is warranted that we find economic ways to preserve, and purify the available water resources. In this presentation, a discussion on two of the naturally occurring and most widespread contaminants in the world and their human exposure, how one of these contaminants contributed possibly to a collapse of a thriving ancient civilization and the lessons one can learn from these, …
Variations Of Sedimentary Biogenic Silica In The Gulf Of Mexico During The Deepwater Horizon And Ixtoc-I Oil Spill., Jong Jin Lee
Variations Of Sedimentary Biogenic Silica In The Gulf Of Mexico During The Deepwater Horizon And Ixtoc-I Oil Spill., Jong Jin Lee
USF Tampa Graduate Theses and Dissertations
The goal of this research is to understand the impacts of the 2010 Deepwater Horizon oil spill and the 1970-1980 IXTOC-I oil spill and other anthropogenic activity (e.g. dam construction) on surface water primary productivity by measuring sedimentary biogenic silica. It is known that sedimentary biogenic silica is distinct from mineral – bound silica, therefore it has been used as a proxy record for surface water primary productivity (e.g. diatom blooms). The Deepwater Horizon oil spill resulted in a widespread Marine Oil Snow Sedimentation and Flocculent Accumulation (MOSSFA) event. The IXTOC-I oil spill was one of the largest oil spills …
Exploring Geochemical Proxies For Identifying Cryptic Sequence Boundaries In The Geologic Past Using Modern Bahamian Analogues, Evan B. Magette
Exploring Geochemical Proxies For Identifying Cryptic Sequence Boundaries In The Geologic Past Using Modern Bahamian Analogues, Evan B. Magette
LSU Master's Theses
Previous studies of carbonate diagenesis have suggested that bulk Sr concentrations and inorganic δ13C values may be a useful proxy for identifying cryptic sequence boundaries in meteorically altered limestones due to geochemical processes associated with carbonate mineral stabilization in cement precipitation in the meteoric diagenetic environment. However, it is possible that natural geochemical variation in sediments may produce geochemical shift which could be misinterpreted as a cryptic sequence boundary. To test this, the Two Pines roadcut containing a previously identified protosol on Eleuthera, Bahamas, which has been affected by vadose meteoric diagenesis was sampled for bulk geochemical analysis. …
Assessing Paleo-Coastal Caves Evolution And Sea Level Changes In Mallorca: Results From Radiometric Dating Of Speleothems, Giuseppe Lucia
Assessing Paleo-Coastal Caves Evolution And Sea Level Changes In Mallorca: Results From Radiometric Dating Of Speleothems, Giuseppe Lucia
USF Tampa Graduate Theses and Dissertations
Sea level affects the littoral morphology and structure in different ways. In coastal karst basins, dissolutional and depositional processes are strictly related to sea level variation. A great variety of karst-related geomorphological features and cave deposits exist above, below, and at sea level, and are extremely useful to study past changes of relative sea level. Within these, vadose speleothems such as flowstones and stalagmite, can document unequivocal maximum sea level constraints as well as record phreatic phases of sea level rise. Here we present a series of geochronological data from the eastern Mallorca and show the implication of relative sea …
Tree-Ring Isotopes Adjacent To Lake Superior Reveal Cold Winter Anomalies For The Great Lakes Region Of North America, Steven L. Voelker, Simon S.-Y Wang, Todd E. Dawson, John S. Roden, Christopher J. Still, Fred J. Longstaffe, Avner Ayalon
Tree-Ring Isotopes Adjacent To Lake Superior Reveal Cold Winter Anomalies For The Great Lakes Region Of North America, Steven L. Voelker, Simon S.-Y Wang, Todd E. Dawson, John S. Roden, Christopher J. Still, Fred J. Longstaffe, Avner Ayalon
Earth Sciences Publications
Tree-ring carbon isotope discrimination (Δ13C) and oxygen isotopes (δ18O) collected from white pine (Pinus strobus) trees adjacent to Lake Superior show potential to produce the first winter-specific paleoclimate reconstruction with inter-annual resolution for this region. Isotopic signatures from 1976 to 2015 were strongly linked to antecedent winter minimum temperatures (Tmin), Lake Superior peak ice cover, and regional to continental-scale atmospheric winter pressure variability including the North American Dipole. The immense thermal inertia of Lake Superior underlies the unique connection between winter conditions and tree-ring Δ13C and δ18O …
Iron Mediated Organic Preservation In A River Influenced Continental Margin, Neha Ajit Ghaisas
Iron Mediated Organic Preservation In A River Influenced Continental Margin, Neha Ajit Ghaisas
LSU Doctoral Dissertations
Continental margins such as the Mississippi river influenced Louisiana shelf (MIS), are important land-ocean interfaces where excessive water column productivity and rapid burial results in large amounts of organic carbon (OC) being sequestered in the sediments. The preservation of OC in sediments is controlled by a number of processes among which mineral-OC interactions are considered to be more important. Specifically, the interactions between sediment iron (Fe) species and OC have been shown to promote carbon preservation. However, the exact nature of preservation mechanism is not well understood and is based on limited global data, which specifically lacks estimates from large …
Cave Dripwater Isotopic Signals Related To The Altitudinal Gradient Of Mount-Lebanon: Implication For Speleothem Studies, Carole Nehme, Sophie Verheyden, Fadi H. Nader, Jocelyne Adjizian-Gerard, Dominique Genty, Kevin De Bont, Benedicte Minster, Ghada Salem, David Verstraten, Philippe Clayes
Cave Dripwater Isotopic Signals Related To The Altitudinal Gradient Of Mount-Lebanon: Implication For Speleothem Studies, Carole Nehme, Sophie Verheyden, Fadi H. Nader, Jocelyne Adjizian-Gerard, Dominique Genty, Kevin De Bont, Benedicte Minster, Ghada Salem, David Verstraten, Philippe Clayes
International Journal of Speleology
An important step in paleoclimate reconstructions based on vadose cave carbonate deposits or speleothems is to evaluate the sensitivity of the cave environment and speleothems to regional climate. Accordingly, we studied four caves, located at different altitudes along the western flank of Mount-Lebanon (Eastern Mediterranean). The objectives of this study are to identify the present-day variability in temperature, pCO2, and water isotopic composition and to assess the possible influence of the altitudinal gradient on cave drip waters and cave streams. We present here an overview of the spatial variability of rainwater based on local and regional data, and …
Multivariate Analysis Of Hydrochemical Data For Jewel Cave, Wind Cave, And Surrounding Areas, Andrew J. Long, James B. Paces, William G. Eldridge
Multivariate Analysis Of Hydrochemical Data For Jewel Cave, Wind Cave, And Surrounding Areas, Andrew J. Long, James B. Paces, William G. Eldridge
United States National Park Service: Publications
Abstract
Jewel Cave National Monument and Wind Cave National Park in South Dakota contain two of the six longest caves worldwide. These caves contain subterranean lakes that are important points of intersection between the water table of the Madison aquifer and the caves. During 2015 to 2017, several subterranean lakes were discovered in Jewel Cave, which previously was thought to be above the regional water table. The objectives of this study were to better understand the hydrology of the recently discovered subterranean lakes in Jewel Cave and to evaluate their relation or possible connection to similar lakes in Wind Cave. …
Isolution 1.0: An Isotope Evolution Model Describing The Stable Oxygen (Δ18O) And Carbon (Δ13C) Isotope Values Of Speleothems, Michael Deininger, Denis Scholz
Isolution 1.0: An Isotope Evolution Model Describing The Stable Oxygen (Δ18O) And Carbon (Δ13C) Isotope Values Of Speleothems, Michael Deininger, Denis Scholz
International Journal of Speleology
Stable oxygen and carbon isotope ratios (δ13C and δ18O) are the most applied climate and environmental proxies in speleothems allowing to infer past changes in cave drip water δ13C and δ18O related to climate and environmental variations from above the cave. However, disequilibrium isotope fractionation processes can modify δ13C and δ18O values in speleothems, which is in most cases difficult to estimate due to inter-dependencies on various cave specific parameter. To better understand the effect of these disequilibrium isotope fractionation processes proxy system models were developed in recent …
A Multi-Proxy Approach To Refining Paleotempestology Records On The Northern Gulf Of Mexico Coast, Marianne Elizabeth Dietz
A Multi-Proxy Approach To Refining Paleotempestology Records On The Northern Gulf Of Mexico Coast, Marianne Elizabeth Dietz
LSU Doctoral Dissertations
Reconstructing pre-historic hurricane activity is typically accomplished through the analysis of sandy overwash deposits identified in coastal lake settings. This method has been used successfully in many parts of the world and can extend the hurricane record thousands of years into the past. However, this approach also has its limitations. This dissertation addresses some of the limitations associated with geologic proxies used to reconstruct hurricane landfalls in the absence of historic data and tests new proxies for the identification of hurricane-derived overwash deposits. Modern storm deposits from two sites on the northern Gulf of Mexico coast are analyzed in detail …
Stable Isotopes Of Clay Minerals From Autoclave Tests Of Oil Sands: Implications For Clay Formation During Steaming Of Alberta Clearwater Oil Sands, Shaoneng He, Fred J. Longstaffe, Zhihong Zhou
Stable Isotopes Of Clay Minerals From Autoclave Tests Of Oil Sands: Implications For Clay Formation During Steaming Of Alberta Clearwater Oil Sands, Shaoneng He, Fred J. Longstaffe, Zhihong Zhou
Earth Sciences Publications
In an effort to evaluate mineral-water isotopic exchange during cyclic steam stimulation (CSS), solutions and<2 μm berthierine-dominated solids from the Clearwater Formation oil sands of Alberta, Canada were analyzed for stable isotope compositions before and after reaction in autoclaves for 1008 h at 250 °C. There was no significant change in solution δ18O and δ2H, which is consistent with the high water/mineral ratio used in the experiments. The solids showed a marked decrease in both δ18O and δ2H following the experiments. Pre-run solids have δ18O of +9.5 to +12.9‰and …2>
Reframing The Mammoth Steppe: Insights From Analysis Of Isotopic Niches, Rachel Schwartz-Narbonne, Fred J. Longstaffe, Kevin J. Karydynal, Patrick Druckenmiller, Keith A. Hobson, Christopher N. Jass, Jessica Z. Metcalfe, Grant Zazula
Reframing The Mammoth Steppe: Insights From Analysis Of Isotopic Niches, Rachel Schwartz-Narbonne, Fred J. Longstaffe, Kevin J. Karydynal, Patrick Druckenmiller, Keith A. Hobson, Christopher N. Jass, Jessica Z. Metcalfe, Grant Zazula
Earth Sciences Publications
Woolly mammoth (Mammuthus primigenius), horse (Equus spp.) and bison (Bisonspp.) coexisted with a variety of mammalian megafauna across the Pleistocene mammoth steppe e a megacontinental ecosystem that spanned northern Eurasia and northwestern North America. Previous research has suggested that highly conserved niches with minimal niche overlap allowed high levels of species diversity on the mammoth steppe. Here we evaluate previously published and some new collagen carbon and nitrogen isotope data (delta13C, delta15N) for mammoth steppe megaherbivores using Stable Isotope Bayesian Ellipses in R (SIBER) and linear regression models to determine isotopic …
Fluid-Present Anatexis Of Neoarchean Tonalite And Amphibolite In The Western Shandong Province, Chris Yakymchuk, Wenran Zhao, Yusheng Wan, Shoufa Lin, Fred Longstaffe
Fluid-Present Anatexis Of Neoarchean Tonalite And Amphibolite In The Western Shandong Province, Chris Yakymchuk, Wenran Zhao, Yusheng Wan, Shoufa Lin, Fred Longstaffe
Earth Sciences Publications
Metatonalite and amphibolite from the Taishan region of the Western Shandong Province in the North China Craton record c. 2.60 Ga fluid-present partial melting via the breakdown of biotite, plagioclase and quartz to produce peritectic hornblende and anatectic melt. Eight paired leucosome–melanosome samples from metatonalite and three paired samples from amphibolite were investigated to evaluate the composition of the melt. Hornblende, biotite and plagioclase in the leucosomes and hornblende and plagioclase in melanosomes from both rock types have similar compositions. Two leucosome samples from the metatonalite were influenced by the removal of heavy rare earth element-rich hornblende and the accumulation …
Stable Isotopic Characterization Of A Coastal Floodplain Forest Community: A Case Study For Isotopic Reconstruction Of Mesozoic Vertebrate Assemblages, Thomas M. Cullen, Fred Longstaffe, Ulrich G. Wortmann, Mark B. Goodwin, Li Huang, David C. Evans
Stable Isotopic Characterization Of A Coastal Floodplain Forest Community: A Case Study For Isotopic Reconstruction Of Mesozoic Vertebrate Assemblages, Thomas M. Cullen, Fred Longstaffe, Ulrich G. Wortmann, Mark B. Goodwin, Li Huang, David C. Evans
Earth Sciences Publications
Stable isotopes are powerful tools for elucidating ecological trends in extant vertebrate communities, though their application to Mesozoic ecosystems is complicated by a lack of extant isotope data from comparable environments/ecosystems (e.g. coastal floodplain forest environments, lacking significant C4 plant components). We sampled 20 taxa across a broad phylogenetic, body size, and physiological scope from the Atchafalaya River Basin of Louisiana as an environmental analogue to the Late Cretaceous coastal floodplains of North America. Samples were analysed for stable carbon, oxygen and nitrogen isotope compositions from bioapatite and keratin tissues to test the degree of ecological resolution that can …
Flood-Inundation Maps For The North Platte River At Scottsbluff And Gering, Nebraska, 2018, Kellan R. Strauch
Flood-Inundation Maps For The North Platte River At Scottsbluff And Gering, Nebraska, 2018, Kellan R. Strauch
United States Geological Survey: Publications
Digital flood-inundation maps for an 8.8-mile reach of the North Platte River, from 1.5 miles upstream from the Highway 92 bridge to 3 miles downstream from the Highway 71 bridge in Scottsbluff County, were created by the U.S. Geological Survey (USGS) in cooperation with the Cities of Scottsbluff and Gering, Nebraska. The flood-inundation maps, which can be accessed through the Flood Inundation Mapping (FIM) Program website at https://www.usgs.gov/mission-areas/water-resources/science/flood-inundation-mapping-fim-program?qt-science_center_objects=0#qt-science_center_objects, depict estimates of the areal extent and depth of flooding corresponding to selected water levels (stages) at the USGS streamgage on the North Platte River at Scottsbluff, Nebr. (station number 06680500). Near-real-time …
Evaluating The Iron Geochemistry Of Terrestrial Aerosol Sources To The Subarctic Pacific Ocean, Meg Yoder
Evaluating The Iron Geochemistry Of Terrestrial Aerosol Sources To The Subarctic Pacific Ocean, Meg Yoder
Honors Theses
Wind-blown dust and volcanic ash deposited in high nutrient, low chlorophyll (HNLC) regions can fertilize phytoplankton by providing iron and other trace nutrients, in turn impacting ecosystems as well as the global carbon and nitrogen cycles. The second largest HNLC region in the world is the northeastern subarctic Pacific. Aeolian transport to this region deposits lithogenic material including desert-derived dust from Asia, glacier-derived dust from Alaska and northwestern Canada, and volcanic ash from Eurasia and North America.
This research aims to assess the geochemistry of aerosol sources to the northeastern subarctic Pacific in relation to the biological availability of iron. …
Biodiversity And Distribution Of Benthic Foraminifera In Harrington Sound, Bermuda: The Effects Of Physical And Geochemical Factors On Dominant Taxa, Nam Le
Honors Theses
Harrington Sound, Bermuda, is a nearly enclosed lagoon acting as a subtropical/tropical, carbonate-rich basin in which carbonate sediments, reef patches, and carbonate-producing organisms accumulate. Here, one of the most important calcareous groups is the Foraminifera. Analyses of common benthic orders, including miliolids (Quinqueloculina and Triloculina spp.) and rotaliids (Homotrema rubrum, Elphidium spp., and Ammonia beccarii), are essential in understanding past and present environmental conditions affecting the island's coastal environment. These taxa have been studied previously; however, factors explaining their individual patterns of abundance in the Sound are not well detailed. The goal of this study is …
Provenance, Redox Conditions, And Diagenesis Of Shales In Chang 7 Member Of Upper Triassic Yanchang Formation, Ordos Basin, China, Bin Sun
Doctoral Dissertations
“This study aims to decipher provenance, redox conditions, and burial history of shales in Chang 7 Member of Upper Triassic Yanchang Formation, Ordos Basin, China. The first paper discusses the origins of single-channeled, vertical, sinuous, and calcite-bitumen-filled cracks in the shales. Results show that in early diagenesis, unconsolidated mud was expanded open by escaping gases produced during organic matter maturation under hydrothermal influences. Calcite initially filled the cracks; bitumen and pyrite came in later and occupied the cracks in various ways. Compaction occurred next and folded the calcite- and bitumen-filled cracks into sinuous shapes. The second paper uses geochemical and …
Formation Of Water-Soluble Organic Matter Through Fungal Degradation Of Lignin, Seyyedhadi Khatami, Ying Deng, Ming Tien, Patrick G. Hatcher
Formation Of Water-Soluble Organic Matter Through Fungal Degradation Of Lignin, Seyyedhadi Khatami, Ying Deng, Ming Tien, Patrick G. Hatcher
Chemistry & Biochemistry Faculty Publications
Lignin is a major component of decaying terrestrial vegetation in soils and has been reported to contribute substantially to the formation of soil carbon humus and associated water extracts of soil. To better understand this process of humification, lignin from brown-rot degraded wood is subjected to a white-rot fungus (Phanerochaete chrysosporium)whose enzymes are particularly effective in lignin degradation. This enzymatic attack was monitored by ultrahigh resolution mass spectrometry of water soluble extracts of the fungal cultures. The ensuing molecular level characterizations showed that the P. chrysosporium fungi induced aromatic ring oxidations followed by ring opening as expected. However, …
The Petrogenesis Of The No Agua High-Silica Rhyolite In The Taos Plateau Volcanic Field, Northern New Mexico, Kevin M. Voelz
The Petrogenesis Of The No Agua High-Silica Rhyolite In The Taos Plateau Volcanic Field, Northern New Mexico, Kevin M. Voelz
Graduate Research Theses & Dissertations
The Taos Plateau volcanic field (TPVF) is located in Northern New Mexico between the eastern flanks of the Tusas Mountains and west of the Sangre de Cristo range. The TPVF is dominantly composed of basaltic lava flows, olivine andesites, and two-pyroxene dacites which erupted from 5.88 to 1.03 Ma. The variety of compositions within the field owes its origin to processes such as magma mixing, fractional crystallization, and crustal assimilation based on chemical modeling. Curiously placed within this spectrum of mafic to intermediate lavas exists the singular high-silica rhyolite of the No Agua Peaks. XRF and ICP-MS analyses from this …
Carbon In The Deep Biosphere: Forms, Fates, And Biogeochemical Cycling, Susan Q. Lang, Magdalena R. Osburn, Andrew D. Steen
Carbon In The Deep Biosphere: Forms, Fates, And Biogeochemical Cycling, Susan Q. Lang, Magdalena R. Osburn, Andrew D. Steen
Faculty Publications
Building on the synthesis of carbon reservoirs in Earth's subsurface, this chapter focuses on the forms, cycling, and fate of the carbon supporting microbial life in the terrestrial and marine subsurface. As the subsurface is estimated to host a vast reservoir of life on Earth, identifying the carbon compounds that life uses for energy and growth is key to understanding ecosystem functioning in the past and at present, and also for extrapolating these findings to the search for life in the universe. This chapter highlights advances in quantifying small carbon compounds, measuring rates of carbon turnover, and the fate of …
Response Of Vegetation In Open And Partially Wooded Fens To Prescribed Burning At Seney National Wildlife Refuge, Jane E. Austin, Wesley E. Newton
Response Of Vegetation In Open And Partially Wooded Fens To Prescribed Burning At Seney National Wildlife Refuge, Jane E. Austin, Wesley E. Newton
United States Geological Survey: Publications
The health and function of northern peatlands, particularly for fens, are strongly affected by fire and hydrology. Fens are important to several avian species of conservation interest, notably the yellow rail (Coturnicops noveboracensis). Fire suppression and altered hydrology often result in woody encroachment, altering the plant community and structure. Woody encroachment and its effects on biodiversity have become an increasing concern in the conservation and management of plant communities. This study evaluated the effects of spring and summer prescribed burns on the plant community, cover, and structure in open and partially wooded fens at Seney National Wildlife Refuge, Michigan, using …
The Medicine Hat Block And The Assembly Of Laurentia: New Interpretations From Single-Grain Zircon Analyses, Blake Oswell Ladouceur
The Medicine Hat Block And The Assembly Of Laurentia: New Interpretations From Single-Grain Zircon Analyses, Blake Oswell Ladouceur
Electronic Theses and Dissertations
The Medicine Hat Block (MHB) is one of the core cratonic elements that amalgamated in the Paleoproterozoic to form Laurentia. However the role of the MHB in the formation of Laurentia is poorly constrained due to virtually all of the MHB being concealed by Proterozoic and younger supracrustal sequences limiting availability of data. The primary sources of samples from the MHB are 1) xenoliths of variable metamorphic grade including gneisses amphibolites and meta-plutonic rocks collected from Eocene volcanic rock; and 2) similar lithologies recovered from boreholes that penetrate to the MHB basement. Previous work on samples from the MHB yielded …
Variability In Groundwater Flow And Chemistry In The Houzhai Karst Basin, Guizhou Province, China, Joshua M. Barna
Variability In Groundwater Flow And Chemistry In The Houzhai Karst Basin, Guizhou Province, China, Joshua M. Barna
Theses and Dissertations--Earth and Environmental Sciences
Understanding how karst aquifers store and transmit water and contaminants is an ongoing problem in hydrogeology. Flowpath and recharge heterogeneity contribute to the complexity of these systems. This thesis explores karst-conduit connectivity and water chemistry variability in the Houzhai catchment in Guizhou province, China. Artificial tracer tests were conducted during both the monsoon and dry seasons to understand temporal variability in connectivity and water velocity between karst features. Multiple flowpaths through the catchment are activated during the monsoon season and partially abandoned during the dry season. Additionally, gradient reversals during monsoonal high-flow events and as a result of pumping can …