Geochemistry Commons^™

Geochemical Analysis And Heat-Treatment Of Natural Sapphires From Madagascar And Tanzania In Oxidizing And Reducing Conditions, Lukas Karuza, Dr. Michael B. Wolf, Brian Konecke Phd

Geology: Student Scholarship & Creative Works

Natural or synthetic sapphires can be heat-treated to improve the clarity by removing “silk” (inclusions) and to change color by introducing color-inducing elements (i.e., chromophores) into the lattice structure or changing their valency. Due to these reasons, sapphires can be heat-treated to increase their monetary value. Twenty natural blue (C1), 20 green (C2), and 20 clear (C3) sapphires from Madagascar and Tanzania were heat-treated in a muffle furnace in oxidizing and reducing conditions, from 1200 to 1600℃, for 10-hour soak time. In total, 5 experiments were conducted in which soak time remained constant: experiment 1 was performed at 1200℃, exp. …

Trends In Streamflow And Precipitation For Selected Sites In The Elkhorn River Basin And In Streamflow In The Salt Creek And Platte River Basins, Nebraska, 1961–2011, Benjamin J. Dietsch, Kellan R. Strauch

United States Geological Survey: Publications

To better understand the streamflow trends at the streamgages in the Elkhorn River Basin in Nebraska, the U.S. Geological Survey (USGS) in cooperation with the Lower Elkhorn Natural Resources District further investigated streamflow trends at the eight streamgages on the Elkhorn River, Salt Creek, and the Lower Platte River that indicated a positive trend in streamflow characteristics and analyzed precipitation trends in the four basins upstream from the Elkhorn River Basin streamgages. An analysis of four streamgages in the Elkhorn River Basin, one streamgage in Salt Creek Basin, and three streamgages in the Lower Platte River Basin that had previously …

Modeling Escherichia Coli In The Missouri River Near Omaha, Nebraska, 2012–16, Brenda K. Densmore, Brent M. Hall, Matthew T. Moser

United States Geological Survey: Publications

The city of Omaha, Nebraska, has a combined sewer system in some areas of the city. In Omaha, Nebr., a moderate amount of rainfall will lead to the combination of stormwater and untreated sewage or wastewater being discharged directly into the Missouri River and Papillion Creek and is called a combined sewer overflow (CSO) event. In 2009, the city of Omaha began the implementation of their Long Term Control Plan (LTCP) to mitigate the effects of CSOs on the Missouri River and Papillion Creek. As part of the LTCP, the city partnered with the U.S. Geological Survey (USGS) in 2012 …

Annotated Bibliography Of Scientific Research On Greater Sage-Grouse Published From 2015 To 2019, Sarah K. Carter, Robert S. Arkle, Heidi L. Bencin, Benjamin R. Harms, Daniel J. Manier, Aaron N. Johnston, Susan L. Phillips, Steven E. Hanser, Zachary H. Bowen

United States Geological Survey: Publications

The greater sage-grouse (Centrocercus urophasianus; hereafter GRSG) has been a focus of scientific investigation and management action for the past two decades. The 2015 U.S. Fish and Wildlife Service listing determination of “not warranted” was in part due to a large-scale collaborative effort to develop strategies to conserve GRSG populations and their habitat and to reduce threats to both. New scientific information augments existing knowledge and can help inform updates or modifications to existing plans for managing GRSG and sagebrush ecosystems. However, the sheer number of scientific publications can be a challenge for managers tasked with evaluating and …

Groundwater Availability Of The Northern High Plains Aquifer In Colorado, Kansas, Nebraska, South Dakota, And Wyoming, Steven M. Peterson, Jonathan P. Traylor, Moussa Guira

United States Geological Survey: Publications

The Northern High Plains aquifer underlies about 93,000 square miles of Colorado, Kansas, Nebraska, South Dakota, and Wyoming and is the largest subregion of the nationally important High Plains aquifer. Irrigation, primarily using groundwater, has supported agricultural production since before 1940, resulting in nearly $50 billion in sales in 2012. In 2010, the High Plains aquifer had the largest groundwater withdrawals of any major aquifer system in the United States.Nearly one-half of those withdrawals were from the Northern High Plains aquifer, which has little hydrologic interaction with parts of the aquifer farther south. Land-surface elevation ranges from more than 7,400 …

Biotic And Abiotic Factors Influencing Arsenic Biogeochemistry And Toxicity In Fluvial Ecosystems: A Review, Laura Barral-Fraga, María Teresa Barral, Keeley L. Macneill, Diego Martiñá-Prieto, Soizic Morin, María Carolina Rodríguez-Castro, Baigal-Amar Tuulaikhuu, Helena Guasch

School of Natural Resources: Faculty Publications

This review is focused on the biogeochemistry of arsenic in freshwaters and, especially, on the key role that benthic microalgae and prokaryotic communities from biofilms play together in through speciation, distribution, and cycling. These microorganisms incorporate the dominant iAs (inorganic arsenic) form and may transform it to other arsenic forms through metabolic or detoxifying processes. These transformations have a big impact on the environmental behavior of arsenic because different chemical forms exhibit differences in mobility and toxicity. Moreover, exposure to toxicants may alter the physiology and structure of biofilms, leading to changes in ecosystem function and trophic relations. In this …

Lunar Magnetic Field Models From Lunar Prospector And Selene/Kaguya Along‐Track Magnetic Field Gradients, Dhananjay Ravat, M. E. Purucker, N. Olsen

Earth and Environmental Sciences Faculty Publications

We use L1‐norm model regularization of |Br | component at the surface on magnetic monopoles bases and along‐track magnetic field differences alone (without vector observations) to derive high quality global magnetic field models at the surface of the Moon. The practical advantages to this strategy are the following: monopoles are more stable at closer spacing in comparison to dipoles, improving spatial resolution; L1‐norm model regularization leads to sparse models which may be appropriate for the Moon which has regions of localized magnetic field features; and along‐track differences reduce the need for ad‐hoc external field noise reduction strategies. We examine also …

Crustal Composition And Moho Variations Of The Central And Eastern United States: Improving Resolution And Geologic Interpretation Of Earthscope Usarray Seismic Images Using Gravity, H. L. Zhang, Dhananjay Ravat, A. R. Lowry

Earth and Environmental Sciences Faculty Publications

EarthScope's USArray Transportable Array has shortcomings for the purpose of interpreting geologic features of wavelengths less than the Transportable Array station spacing, but these can be overcome by using higher spatial resolution gravity data. In this study, we exploit USArray receiver functions to reduce nonuniqueness in the interpretation of gravity anomalies. We model gravity anomalies from previously derived density variations of sedimentary basins, crustal V p /V s variation, Moho variation, and upper mantle density variation derived from body wave imaging informed by surface wave tomography to estimate V p/V s. Although average densities and density contrasts for these seismic …

History Of Natural And Anthropogenic Activities In Lake Izabal, Eastern Guatemala: Using Geochemical Evidence To Record Recent Contamination, Elisandra Hernandez

Doctoral Dissertations

”Water is essential for human subsistence. Stable freshwater supplies are needed as a source of food, drinking water, for transportation, recreation and economic development. Despite their recognized importance, anthropogenic activities have altered freshwater ecosystems around the world. Lake Izabal is the habitat for diverse aquatic species of flora and fauna, some of which are endemic and endangered. Its importance notwithstanding, anthropogenic activities developed in Lake Izabal’s catchment in recent years have compromised its status. This study used paleolimnological techniques to link past and recent anthropogenic activities such as mining operations and recent tilapia aquaculture. Relative abundances and concentrations of Pb, …

Cobalt Partitioning And Solubility In Low-Temperature Carbonate-Hydrothermal Systems, Seth Kurtis Coursey

Graduate Research Theses & Dissertations

Cobalt mineralization has been documented in low temperature Mississippi Valley-type (MVT) deposits in southeast Missouri. Lead and zinc are the most economically important metals in these deposits and are contained within galena (PbS) and sphalerite (ZnS), respectively. Cobalt is also mined in some of the deposits with cobalt-bearing ores, e.g., siegenite ((Ni,Co)3S4) and fletcherite (Cu,(Ni,Co)2S4), occurring stratigraphically below main-stage galena and sphalerite. The hydrothermal fluids responsible for cobalt mineralization are thought to be chemically distinct from the predominant MVT ore-bearing fluids and represent a distinct mineralizing event. Cobalt is likely transported as CoCl2 in hydrothermal fluids and sourced from structures …

Isotopic And Geochemical Tracers Of Groundwater Flow In The Shivwits Plateau, Grand Canyon National Park, Jonathan W. Wilson

Theses and Dissertations--Earth and Environmental Sciences

As the impacts of global climate change on water resources continue to become more apparent, proper understanding and management of groundwater resources will be needed as supplies become more strained. Traditional methods of characterizing groundwater systems are time-intensive, costly, and can be difficult to complete in remote areas. Using ambient geochemical tracers from discrete sampling could aid in characterizing spring systems through determining flow paths, recharge areas, and carbon cycling. However, using discrete seasonal samples to understand the hydrogeology of complex, mixed-lithology aquifers has not been extensively examined. Here we explore using δ¹³C of dissolved organic carbon (DOC), …

“The Tale Of 3,000 Zircons”: An Investigation Of Grenville Sedimentation In Amazonia Using U/Pb Detrital Zircon Geochronology, Felicia R. Harris

Theses and Dissertations--Earth and Environmental Sciences

The continental collision between Laurentia and Amazonia that generated Rodinia and the Grenville Orogen is proposed to be one of the largest, hottest and longest-lived orogens in Earth history. Subsequent erosion and weathering led to a mountain range’s worth of sediment recycled into clastic systems across North America, otherwise known as the “Great Grenville Sedimentation Event”. The Sunsas orogeny in Amazonia is correlative to the Grenville in North America and is proposed to be the result of final Rodinian collision at 1200-1000 Ma. Despite the connection between the two ranges and the robust sedimentary record in North America, little work …

Altitude Of The Potentiometric Surface In The Mississippi River Valley Alluvial Aquifer, Spring 2018, Virginia L. Mcguire, Ronald C. Seanor, William H. Asquith, Anna M. Nottmeier, David C. Smith, Roland W. Tollett, Wade H. Kress, Kellan R. Strauch

United States Geological Survey: Publications

The Mississippi River Valley alluvial (MRVA) aquifer is an important surficial aquifer in the Mississippi Alluvial Plain (MAP) area. The aquifer is generally considered to be an unconfined aquifer (fig. 1; Clark and others, 2011), and withdrawals are primarily used for irrigation (Maupin and Barber, 2005). These groundwater withdrawals have resulted in substantial areas of water-level decline in parts of the aquifer. Concerns about water-level declines and the sustainability of the MRVA aquifer have prompted the U.S. Geological Survey (USGS), as part of the USGS Water Availability and Use Science Program and with assistance from other Federal, State, and local …

Water Quality Of Groundwater Used For Public Supply In Principal Aquifers Of The Western United States, Celia C. Rosencrans, Marylynn Musgrove

United States Geological Survey: Publications

Groundwater provides nearly half of the Nation’s drinking water. As the Nation’s population grows, the importance of (and need for) high-quality drinking-water supplies increases. As part of a national-scale effort to assess groundwater quality in principal aquifers (PAs) that supply most of the groundwater used for public supply, the U.S. Geological Survey National Water-Quality Assessment (NAWQA) Project staff sampled six principal aquifers in the western United States between 2013 and 2017: (1) the Basin and Range carbonate-rock aquifers, (2) Basin and Range basin-fill aquifers, (3) Rio Grande aquifer system, (4) High Plains aquifer, (5) Colorado Plateaus aquifers, and (6) Columbia …

Estimated Groundwater Withdrawals From Principal Aquifers In The United States, 2015, John K. Lovelace, Martha G. Nielsen, Amy L. Read, Chid J. Murphy, Molly A. Maupin

United States Geological Survey: Publications

In 2015, about 84,600 million gallons per day (Mgal/d) of groundwater were withdrawn in the United States for various uses including public supply, self-supplied domestic, industrial, mining, thermoelectric power, aquaculture, livestock, and irrigation. Of this total, about 94 percent (79,200 Mgal/d) was withdrawn from principal aquifers, which are defined as regionally extensive aquifers or aquifer systems that have the potential to be used as sources of water of suitable quality and quantity to meet various needs. The remaining 6 percent (5,400 Mgal/d) was withdrawn from other, nonprincipal aquifers in the United States. Sixty-six principal aquifers belonging to 5 major lithologic …

Physical And Chemical Properties Of Clastic Sediments From Two Caves In The Northern Karst Region Of Puerto Rico, Autum R. Downey

Graduate Theses, Dissertations, and Problem Reports (ETD)

Geochemical properties and organic characteristics are essential to understanding the general depositional dynamics of a cave. Most work on clastic cave sediments focuses on physical properties of sediments. Little work has been done on bulk organic matter and geochemical properties.

This project reports physical and geochemical characterization of cave sediments from two caves in the northern karst region of Puerto Rico: El Tallonal Cave and Cueva Clara. Core and grab samples were collected and analyzed for particle size, total organic carbon, total nitrogen, organic matter characteristics using fluorescence spectroscopy, and major and minor elements using X-ray fluorescence (XRF). The sediments …

Investigating Effects Of Carbonate Minerals On Shale- Hydraulic Fracturing Fluid Interactions In The Marcellus Shale, Brennan Matthew Ferguson

Graduate Theses, Dissertations, and Problem Reports (ETD)

Natural gas extracted from tight shale formations, such as the Marcellus Shale, represent an important and developing front in energy exploration. By fracturing these formations using pressurized fracturing fluid, previously unobtainable hydrocarbon reserves may be tapped. While pursuing this resource hydraulic fracturing operations leave chemically complex fluids in the shale formation for at least two weeks. This provides a substantial opportunity for the hydraulic fracturing fluid (HFF) to react with the shale formation at reservoir temperature and pressure. In this study, we investigated the effects of the carbonates on shale-HFF reactions with a focus on the Marcellus Shale. We determined …

Reconstructing Hydrologic Conditions And Metals Supplied By The Peace River To The Peace-Athabasca Delta, Jelle André Faber

Theses and Dissertations (Comprehensive)

The Peace-Athabasca Delta (PAD) in northern Alberta, Canada, is recognized internationally for its ecological, historical, and cultural significance. The delta is mostly within Wood Buffalo National Park, a UNESCO World Heritage Site, and is a Ramsar Wetland of International Importance. The construction of the WAC Bennett Dam (1967) and the Site C Dam (ongoing, 2024) on the Peace River, and expansion of the Alberta Oil Sands industry along the Athabasca River have raised concerns over water quantity and quality in the delta. When industry operations began, effective monitoring had not been implemented. Consequently, pre-industrial reference conditions are unknown and can …

Mineral Compositions Of Meteorite Samples Alha 77005, Nwa 7397, Nwa 5480, And Ausson: Implications For Geodynamic Processes On Their Parent Bodies And Meteorite Reclassification, Kaylin Agnata Tunnell

Masters Theses

“This study investigates the major, minor, and trace element compositions of minerals from a series of meteorites which represent different stages of planetary evolution including two sample from Mars (ALHA 77005 and NWA 7397), one sample from Vesta (NWA 5480), and one ordinary chondrite (Ausson). The goal of this study is to investigate if petrogenetic tracers commonly employed to understand terrestrial samples can also be applied to extraterrestrial samples. The data presented here show that mineral trace element data allow for novel insight into the magmatic history of meteorite samples. For example, V/Sc and Fe/Mn ratios in olivine provide insight …

A Multi-Method Investigation Of The Modern Sedimentation And Late Holocene Paleolimnology Of June Lake (Mono County, Ca), And A Survey-Based Analysis Of Ninth Graders’ Attitudes Towards Geology, Eva Lyon

Theses and Dissertations--Earth and Environmental Sciences

Three distinct manuscripts comprise this dissertation. The first analyzes the modern sedimentary basin of June Lake, a small glacial lake in the eastern Sierra Nevada of California (USA) using a number of data sets, including bathymetry, surface sediment composition, and seismic stratigraphy. The seismic survey revealed sublacustrine morphological features that suggest the basin originated due to ice scour, as well as four acoustically distinct stratigraphic units that reflect the history of sedimentation following glacial scouring. Corroborating the seismic record, sediment cores from the youngest unit are composed of hemipelagically deposited, organic-rich, laminated diatomaceous oozes alternating with coarse tephra beds. The …