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Articles 151 - 180 of 274
Full-Text Articles in Geochemistry
A New Method For Ultra-Low Sulfate Extraction And A Pilot Study In Arid Soils, Marisela Montelongo
A New Method For Ultra-Low Sulfate Extraction And A Pilot Study In Arid Soils, Marisela Montelongo
Open Access Theses & Dissertations
Sulfur in soils is a crucial nutrient for all organisms including plants. Sulfate (SO42-), a water soluable anion, is a good source of this important element. Because of the importance of sulfur for agriculture, the use of sulfate has been well studied in temperate climate zones, and it is generally accepted that microbes play a critical role in controlling the availability of sulfate. Organically bound sulfur, such as sulfate esters and carbon-bonded sulfur, compounds that are generated and decomposed by microbes, are essential sulfur sources for plants under these conditions. For arid environments, knowledge of sulfate turnover in soils by …
Cycling Of Gypsiferous White Sands Aerosols In The Shallow Critical Zone At White Mountain, New Mexico, Patrick Richard Rea
Cycling Of Gypsiferous White Sands Aerosols In The Shallow Critical Zone At White Mountain, New Mexico, Patrick Richard Rea
Open Access Theses & Dissertations
Dry deposition significantly affects evolution of the critical zone by nutrient supply and contributing to soil genesis. Dust influx and cycling in soils are difficult to quantify because dust sources can be chemically similar to local soils. White Sands, New Mexico, emits gypsum dust with a unique chemical and isotopic signature, providing an opportunity to investigate dust deposition and its movement in soils. This study evaluated the mobility of White Sands dust particles in the critical zone at White Mountain, New Mexico, a highland 100 km downwind. Four soil profiles were collected over limestone, igneous, mixed limestone and dolostone, and …
Using Strontium Isotopes In Conjunction With Major, And Trace Elements To Identify Water/Rock Interaction In The Upper Kittitas County, Washington, James Patterson, Carey Gazis
Using Strontium Isotopes In Conjunction With Major, And Trace Elements To Identify Water/Rock Interaction In The Upper Kittitas County, Washington, James Patterson, Carey Gazis
All Master's Theses
The complex bedrock lithologies in the Upper Kittitas County provide an ideal setting for developing isotopic methodology to identify groundwater sources and track flow paths through water-rock interaction. A wide range of 87Sr/86Sr (0.7040 to 0.7068) in surface waters, springs, and groundwater from wells was found, allowing for identification of the individual signatures of lithologic units. Rock leachates from different lithology were compared to water samples to determine a general 87Sr/86Sr signature of the water-rock interaction for that lithology. The signatures identified were systematically lower than their associated waters, but similar enough to identify the expected 87Sr/86Sr of water-rock interaction …
A Complex Legacy Of Contamination In Urban Estuarine Systems, Michael A. Kruge
A Complex Legacy Of Contamination In Urban Estuarine Systems, Michael A. Kruge
Department of Earth and Environmental Studies Faculty Scholarship and Creative Works
Industrialized urban waterways have typically suffered decades of contamination, varying in source and intensity as manufacturing and transportation practices evolved. The U.S. Environmental Protection Agency designates locales with particularly severe contamination as Superfund sites. Among these, the Gowanus Canal and lower Passaic River in the New York/New Jersey harbor estuary illustrate a complex range of contamination types.
The 2.2 km Gowanus Canal, with sluggish circulation driven mostly by tides, accumulated fine-grained sediments (average thickness of 3 m) highly enriched in organic carbon (OC, mean 11 % but up to 49 %) derived from hydrocarbons, sewage, coal, char, and biomass, along …
Chlorine Demand Shows Thresholds And Hierarchy With Source Water Quality At Beaver Lake, Arkansas, Jaime M. Gile
Chlorine Demand Shows Thresholds And Hierarchy With Source Water Quality At Beaver Lake, Arkansas, Jaime M. Gile
Graduate Theses and Dissertations
This study investigated the effects of source water quality in Beaver Lake on the amount of chlorine (Cl) needed to develop decision support system to help guide chlorination practices in pre-treatment of source water. Chlorine demand assays were performed on water samples from Beaver Lake collected from the intake structure at Beaver Water District from March 2014 through August 2015, and using data from these assays, the two points of interest in this study were the Cl dose at which Cl residuals began to accumulate and the mean Cl demand occurring after that dose. Three methods of analysis were used …
Evaluating The Influences Of Karst Hydrogeology On Freshwater Harmful Algal Blooms In Kentucky Lakes, Robert T. Schaefer
Evaluating The Influences Of Karst Hydrogeology On Freshwater Harmful Algal Blooms In Kentucky Lakes, Robert T. Schaefer
Masters Theses & Specialist Projects
A problem exists in Nolin River Lake and Rough River Lake in Kentucky, due to the increasing prevalence of cyanobacterial-based harmful algal blooms (CyanoHABs) and the threats they pose to local communities. These lakes were developed as artificial reservoirs from embankment. Further complicating the issue, the lakes are located within a heavily karstified region and there exists no plan or method currently for monitoring or managing CyanoHABs in a karst region with regard to groundwater inputs to the lake systems or their tributaries. A mixture of techniques and analysis methods was used to determine the best way to monitor and …
Proportions Of Convective And Stratiform Precipitation Revealed In Water Isotope Ratios, Pradeep K. Aggarwal, Ulrike Romatschke, Luis Araguas-Araguas, Dagnachew Belachew, Fred J. Longstaffe, Peter Berg, Courtney Schumacher, Aaron Funk
Proportions Of Convective And Stratiform Precipitation Revealed In Water Isotope Ratios, Pradeep K. Aggarwal, Ulrike Romatschke, Luis Araguas-Araguas, Dagnachew Belachew, Fred J. Longstaffe, Peter Berg, Courtney Schumacher, Aaron Funk
Earth Sciences Publications
Tropical and midlatitude precipitation is fundamentally of two types, spatially-limited and high-intensity convective or widespread and lower-intensity stratiform, owing to differences in vertical air motions and microphysical processes governing rain formation. These processes are difficult to observe or model and precipitation partitioning into rain types is critical for understanding how the water cycle responds to climate changes. Here, we combine two independent data sets – convective and stratiform precipitation fractions, derived from the Tropical Rainfall Measuring Mission satellite or synoptic cloud observations, and stable isotope and tritium compositions of surface precipitation, derived from a global network – to show that …
An Investigation Of Hydrogeologic, Stratigraphic, And Structural Controls On Acer Grandidentatum Communities In A Karst Landscape, Owl Mountain Province, Fort Hood Military Installation, Texas, Melinda S. Faulkner
Electronic Theses and Dissertations
The Owl Mountain Province is located within the Fort Hood Military Installation, an approximately 880 km2 installation established in the 1940s in Bell and Coryell counties, Texas, which has undergone extensive land use changes associated with military training, maintaining much of the vegetation in early succession. This study investigates thelithologic, stratigraphic, and structural controls on the hydrologic, hydrogeologic, and geomorphologic evolution of the Owl Mountain Province as expressed by mesic vegetation communities, including Pleistocene relicts Acer grandidentatum, within karst terrains. These systems exhibit complexly overprinted speleogenetic evolutions within a dynamic groundwater regime resulting from regional climate shifts throughout the …
Agriculture Causes Nitrate Fertilization Of Remote Alpine Lakes, Elizabeth J. Hundey, Sam S.D. Russell, Fred Longstaffe, Katrina A. Moser
Agriculture Causes Nitrate Fertilization Of Remote Alpine Lakes, Elizabeth J. Hundey, Sam S.D. Russell, Fred Longstaffe, Katrina A. Moser
Earth Sciences Publications
Humans have altered Earth’s nitrogen cycle so dramatically that reactive nitrogen (Nr) has doubled. This has increased Nr in aquatic ecosystems, which can lead to reduced water quality and ecosystem health. Apportioning sources of Nr to specific ecosystems, however, continues to be challenging, despite this knowledge being critical for mitigation and protection of water resources. Here we use D17O, d18O and d15N from Uinta Mountain (Utah, USA) snow, inflow and lake nitrate in combination with a Bayesian-based stable isotope mixing model, to show that at least 70% of nitrates in aquatic systems are anthropogenic …
Processes Controlling Carbon Cycling In Antarctic Glacier Surface Ecosystems, Elizabeth A. Bagshaw, Martyn Tranter, Jemma L. Wadham, Andrew G. Fountain, A. Dubnick, S. Fitzsimons
Processes Controlling Carbon Cycling In Antarctic Glacier Surface Ecosystems, Elizabeth A. Bagshaw, Martyn Tranter, Jemma L. Wadham, Andrew G. Fountain, A. Dubnick, S. Fitzsimons
Geology Faculty Publications and Presentations
Glacier surface ecosystems, including cryoconite holes and cryolakes, are significant contributors to regional carbon cycles. Incubation experiments to determine the net production (NEP) of organic matter in cryoconite typically have durations of 6-24 hours, and produce a wide range of results, many of which indicate that the system is net heterotrophic. We employ longer term incubations to examine the temporal variation of NEP in cryoconite from the McMurdo Dry Valleys, Antarctica to examine the effect of sediment disturbance on system production, and to understand processes controlling production over the lifetimes of glacier surface ecosystems. The shorter-term incubations have durations of …
Geochemical Processes And Controls Affecting Water Quality Of The Karst Area Of Big Creek Near Mt. Judea, Arkansas, V. Brahana, J. Nix, C. Kuyper, T. Turk, F. Usrey, S. Hodges, C. Bitting, K. Ficco, E. Pollock, R. Quick, B. Thompson, J. Murdoch
Geochemical Processes And Controls Affecting Water Quality Of The Karst Area Of Big Creek Near Mt. Judea, Arkansas, V. Brahana, J. Nix, C. Kuyper, T. Turk, F. Usrey, S. Hodges, C. Bitting, K. Ficco, E. Pollock, R. Quick, B. Thompson, J. Murdoch
Journal of the Arkansas Academy of Science
Karst regions typically are considered to be vulnerable with respect to various land-use activities, owing to the intimate association of surface and groundwater and lack of contaminant attenuation provided by most karst aquifers. Inasmuch as the soluble rocks of the karst landscape can be dissolved to create large, rapid-flow zones that compete successfully with surface streams, groundwater and subsurface flow represent a much larger component of the hydrologic budget in karst regions than in areas where non-soluble rocks predominate. Karst areas typically are distinguished by being unique, but some general approaches can be applied to characterize the hydrology of the …
Using Nitrate, Chloride, Sodium, And Sulfate To Calculate Groundwater Age, Kimm Crawford, Terry Lee
Using Nitrate, Chloride, Sodium, And Sulfate To Calculate Groundwater Age, Kimm Crawford, Terry Lee
Sinkhole Conference 2015
Regression analysis is used to identify monotonic trends to assign water age using ion data from two large well water databases from southeast Minnesota (SE MN). Nitrate (NO3-N), chloride (Cl), sodium (Na), and sulfate (SO4) ions in the commonly used aquifers in SE MN can be used as groundwater tracers since they are either entirely or partly anthropogenic in their sources, their loading occurs on a regional scale, and they are almost entirely conserved. Ion concentrations over time are used to establish six trend patterns. Two patterns are unchanging (background and stable above background), and four are changing (linear up, …
Tracer Studies Conducted Nearly Two Decades Apart Elucidate Groundwater Movement Through A Karst Aquifer In The Frederick Valley Of Maryland, Keith A. White, Michael K. Cobb, Thomas Aley, Ethan Weikel
Tracer Studies Conducted Nearly Two Decades Apart Elucidate Groundwater Movement Through A Karst Aquifer In The Frederick Valley Of Maryland, Keith A. White, Michael K. Cobb, Thomas Aley, Ethan Weikel
Sinkhole Conference 2015
A pair of groundwater tracer studies at a single karst test site were completed 18 years apart. The results of these studies have provided evidence of both relatively rapid advective transport via conduits and an extreme capacity for dye storage and retardation. The tracer results, coupled with other subsurface investigation data, are used to develop a conceptual model for groundwater movement through this karst aquifer in the Frederick Valley of Maryland, as well as identify implications for remediation. Three fluorescent tracer dyes used in the initial study were detected in several background monitoring locations established for the second study conducted …
Using Bromide Tracer To Measure Uranium Diffusivity In Ground Water Sediments, Francis Michael Tee, Morris E. Jones, Megan K. Dustin, Sharon Bone, John Bargar
Using Bromide Tracer To Measure Uranium Diffusivity In Ground Water Sediments, Francis Michael Tee, Morris E. Jones, Megan K. Dustin, Sharon Bone, John Bargar
STAR Program Research Presentations
More than 129 million liters of groundwater are contaminated with uranium at Old Rifle, Colorado – a former uranium-processing site that operated until 1958. The original Department of Energy (DOE) strategy for remediation, involving natural flushing of U from the groundwater through mixing with surface water, has not proven successful. Thin pockets of silt-, clay-, and organic-rich sediments referred to as naturally reduced zones (NRZs) act both as sinks and sources of U to the aquifer, contribute to plume persistence, and appear to be diffusion limited controlled.
To better understand how the NRZs are diffusion limited controlled, a bromide tracer …
Fluxes Of Dissolved Organic Carbon During Storm Events In The Neponset River Watershed, Keith Thomas Cialino
Fluxes Of Dissolved Organic Carbon During Storm Events In The Neponset River Watershed, Keith Thomas Cialino
Graduate Doctoral Dissertations
The transport of dissolved organic carbon (DOC) and chromophoric dissolved organic matter (CDOM) from land to coastal environments strongly influences coastal ecosystems. The presence of first flush phenomena due to rainwater runoff traveling from land into waterways can greatly affect carbon fluxes to coastal areas. This research utilizes sensors, autosamplers, and standard watershed sampling in order to assess for the presence of first flush and its significance. A rainfall simulator was built in order to collect runoff on two land use types. Time series data suggest that first flush of dissolved organic carbon was present for all rainfall intensities simulated …
Geochemical Analysis Of Surface Materials Surrounding The Bautsch-Gray Mine Superfund Site Near Galena, Illinois, Ryan Plath
Geology: Student Scholarship & Creative Works
The Bautsch-Gray zinc and lead mine, near Galena, IL, was in operation from the early 1900s until closing in 1975. The mine’s tailings pile has documented elevated lead and zinc concentrations in the surface materials surrounding the site. Numerous floods have caused contaminated sediment to migrate off the mine tailings pile, across Blackjack Road and into an outwash basin, and towards Smallpox Creek. Since this site was designated an EPA priority list Superfund site in 2010, the EPA has conducted numerous remediation efforts. This study attempts to develop a better understanding of the contamination within the soils of the outwash …
Stable Isotopes As A Tool To Characterize Carbon Cycling And Develop Hydrologic Budgets In Mantled Karst Settings, Katherine Knierim
Stable Isotopes As A Tool To Characterize Carbon Cycling And Develop Hydrologic Budgets In Mantled Karst Settings, Katherine Knierim
Graduate Theses and Dissertations
Isotopes of water (δ2H/δ18O), carbon dioxide (δ13C-CO2), and dissolved inorganic carbon (δ13C-DIC) were used to explore water quality, trace carbon cycling, and quantify recharge sources through mantled karst and into Blowing Spring Cave (BSC). Of the possible sources of contamination in the BSC recharge area, septic-tank effluent was hypothesized to degrade water quality at the spring outlet of BSC because of the dominance of septic tanks for waste treatment, unsuitable topography and soil for septic-tank absorption fields, increased nitrate and chloride concentrations concomitant with increased urbanization, and increased Escherichia coli with discharge. Carbon cycling between the soil and BSC was …
Using Kriging, Cokriging, And Gis To Visualize Fe And Mn In Groundwater, Crystal Johnson
Using Kriging, Cokriging, And Gis To Visualize Fe And Mn In Groundwater, Crystal Johnson
Electronic Theses and Dissertations
For aesthetic, economic, and health-related reasons, allowable concentrations of iron (Fe) and manganese (Mn) found present in drinking water are 0.3 mg/L and 0.05 mg/L, respectively. Water samples taken from private drinking wells in the rural communities within Buncombe County, North Carolina contain amounts of these metals in concentrations higher than the suggested limits. This study focused on bedrock geology, elevation, saprolite thickness, and well depth to determine factors affecting Fe and Mn. Using ArcGIS 10.2, spatial trends in Fe and Mn concentrations ranges were visualized, and estimates of the metal concentrations were interpolated to unmonitored areas. Results from this …
On The Influence Of Ionic Strength On Radium And Strontium Sorption To Sandy Loam Soils, Brian A. Powell, Todd Miller, Daniel I. Kaplan
On The Influence Of Ionic Strength On Radium And Strontium Sorption To Sandy Loam Soils, Brian A. Powell, Todd Miller, Daniel I. Kaplan
Journal of the South Carolina Academy of Science
Models which can estimate environmental transport of radioactive contaminants in natural and engineered systems are required to 1) deploy effective remediation strategies for contaminated sites, 2) design waste repositories for future waste streams, and 3) ensure protection of human and environmental health in all cases. These models require accurate transport parameters in order to correctly predict how these contaminants will move in the subsurface. This work aimed to determine more accurately the distribution coefficients for radium and strontium sorption to Savannah River Site (SRS) soils. Radium and strontium sorption to the soils was found to be highly dependent upon ionic …
The Relationship Between Carbon Dioxide Concentration And Visitor Numbers In The Homothermic Zone Of The Balcarka Cave (Moravian Karst) During A Period Of Limited Ventilation, Marek Lang, Jiří Faimon, Camille Ek
The Relationship Between Carbon Dioxide Concentration And Visitor Numbers In The Homothermic Zone Of The Balcarka Cave (Moravian Karst) During A Period Of Limited Ventilation, Marek Lang, Jiří Faimon, Camille Ek
International Journal of Speleology
The evolution of CO2 levels with and without human presence was studied in a selected site (Gallery Chamber) of the homothermic zone of the Balcarka Cave (Moravian Karst, Czech Republic) during the fall, a period of limited ventilation. There were recognized various factors controlling the cave CO2 levels under different conditions in the exterior and interior. When visitors were absent, CO2 levels were controlled by the advective CO2 fluxes linked to cave airflows and reaching up to ~1.5x10-3 mol s-1. These fluxes exceed by orders of magnitude the exchanged diffusive fluxes (up to …
Characterization Of The Major Ions Of Coal Creek Near Cedar City, Utah, Jared Bryce Weaver, Christopher Lamb, Kim Weaver, Jason Kaiser, J. Ty Redd
Characterization Of The Major Ions Of Coal Creek Near Cedar City, Utah, Jared Bryce Weaver, Christopher Lamb, Kim Weaver, Jason Kaiser, J. Ty Redd
The Compass: Earth Science Journal of Sigma Gamma Epsilon
The major ions of Coal Creek near Cedar City, in southwest Utah, were measured to determine if there were any differences in ion concentrations in July of 2014 as compared with spring measurements of 2012 and 2013. Past analyses have shown higher ion concentrations in lower regions of Coal Creek despite the apparent lack of water input. This research is aimed to better characterize these abrupt increases in concentration and determine if these trends varied when samples were acquired in the summer vs. in the spring when sample acquisition has occurred in the past. Environmental water samples were collected at …
Pyrolysis-Gc-Ms For The Rapid Environmental Forensic Screening Of Contaminated Brownfield Soil, Azucena Lara-Gonzalo, Michael A. Kruge, I Lores, B Gutiérrez, José Luis Gallego
Pyrolysis-Gc-Ms For The Rapid Environmental Forensic Screening Of Contaminated Brownfield Soil, Azucena Lara-Gonzalo, Michael A. Kruge, I Lores, B Gutiérrez, José Luis Gallego
Department of Earth and Environmental Studies Faculty Scholarship and Creative Works
An abandoned chemical plant in Asturias (Spain) was studied using a multi-faceted molecular fingerprinting approach, demonstrating that it is possible to: (1) carefully unravel tangled evidence resulting from multiple pollution sources, and (2) recognize major contaminants largely ignored by conventional analyses. This methodology employed a battery of GC-MS analyses of liquid chromatographic fractions of soil extracts, plus the pyrolysis products of the soil extract's asphaltene fraction and the whole soil itself. In this example, coal tar distillation and the subsequent production of naphthalene, phenols and polymer resins are responsible for most of the soil contamination. Styrene, naphthalene, indene, and their …
Analytical Pyrolysis Principles And Applications To Environmental Science, Michael A. Kruge
Analytical Pyrolysis Principles And Applications To Environmental Science, Michael A. Kruge
Department of Earth and Environmental Studies Faculty Scholarship and Creative Works
Over the past half century, analytical pyrolysis has proven itself to be an effective means for the semiquantitative characterization of complex macromolecular organic substances. It has been demonstrated that instruments such as Py-FID, Py-MS, and in particular, Py-GC/MS can provide valuable geochemical insights when applied to a wide variety of problems in environmental science. The more widespread use of analytical pyrolysis methods in the evaluation of environmental pollution is recommended, because of their relatively low cost and information-rich results.
Pyrolysis is the heating of organic substances in an inert, oxygen-free atmosphere, thereby avoiding combustion. When performed on a large scale, …
Wetchimp-Wsl: Intercomparison Of Wetland Methane Emissions Models Over West Siberia, T. J. Bohn, J. R. Melton, A. Ito, T. Kleinen, R. Spahni, B. D. Stocker, B. Zhang, X. Zhu, R. Schroeder, M. V. Glagolev, S. Maksyutov, V. Brovkin, G. Chen, S. N. Denisov, A. V. Eliseev, A. Gallego-Sala, K. C. Mcdonald, M. A. Rawlins, W. J. Riley, Z. M. Subin, H. Tian, Q. Zhuang, J. O. Kaplan
Wetchimp-Wsl: Intercomparison Of Wetland Methane Emissions Models Over West Siberia, T. J. Bohn, J. R. Melton, A. Ito, T. Kleinen, R. Spahni, B. D. Stocker, B. Zhang, X. Zhu, R. Schroeder, M. V. Glagolev, S. Maksyutov, V. Brovkin, G. Chen, S. N. Denisov, A. V. Eliseev, A. Gallego-Sala, K. C. Mcdonald, M. A. Rawlins, W. J. Riley, Z. M. Subin, H. Tian, Q. Zhuang, J. O. Kaplan
Publications and Research
Wetlands are the world’s largest natural source of methane, a powerful greenhouse gas. The strong sensitivity of methane emissions to environmental factors such as soil temperature and moisture has led to concerns about potential positive feedbacks to climate change. This risk is particularly relevant at high latitudes, which have experienced pronounced warming and where thawing permafrost could potentially liberate large amounts of labile carbon over the next 100 years. However, global models disagree as to the magnitude and spatial distribution of emissions, due to uncertainties in wetland area and emissions per unit area and a scarcity of in situ observations. …
Salt And Mineral Recovery From High Salinity Waters, Osvaldo Alejandro Broesicke
Salt And Mineral Recovery From High Salinity Waters, Osvaldo Alejandro Broesicke
Open Access Theses & Dissertations
Natural salt springs in the Salt Fork Basin in Crosby County, Texas, result in the natural salt pollution of the Brazos River, rendering it unusable for most potable purposes. Previous research indicates that by intercepting the source of the pollution, water quality of the Brazos River can be greatly improved. This paper investigates and assesses two strategies for salt and mineral recovery using natural brine collected from the Salt Fork Basin, the first of which is presented in a separate work.
The research described in this paper evaluates the potential of a desulfation, soda-caustic softening, acidification/decarbonation, and evaporation process to …
Trace Element Behavior During Coal Combustion: Insights From Cadmium And Zinc Isotope Analysis, Fotios Fouskas
Trace Element Behavior During Coal Combustion: Insights From Cadmium And Zinc Isotope Analysis, Fotios Fouskas
Open Access Theses & Dissertations
Due to its low cost and abundance, coal has been pervasively used in recent decades to meet large energy demands worldwide. Coal combustion provides the dominant electrical source in the U.S and produces over 100 million tons of coal combustion products (CCPs) per year domestically. The disposal/beneficial use of CCPs has the potential to release toxic trace elements, including cadmium (Cd) and zinc (Zn), into the environment. High temperature combustion of coal changes both physical states and chemical properties of Cd and Zn compounds in CCPs. Related processes such as evaporation and condensation, can lead to mass-dependent fractionation of Cd …
The Environmental Effects Of Coal Fires, Trent Garrison
The Environmental Effects Of Coal Fires, Trent Garrison
Theses and Dissertations--Earth and Environmental Sciences
There are thousands of subterranean coal fires in the world that, because of incomplete combustion, emit a wide variety of volatile and semivolatile organic compounds to the atmosphere, water, and soil at concentrations that could pose health risks to humans and wildlife. The main goals of this study were to (1) review methods that are used to characterize physical and chemical characteristics of coal-fire sites, (2) determine relationships between gas emissions and physical and chemical characteristics of coal-fire sites, using a combination of regression and multivariate statistical methods, and (3) determine the concentrations of volatile and semivolatile organic compounds in …
Iron Sources And Dissolved-Particulate Interactions In The Seawater Of The Western Equatorial Pacific, Iron Isotope Perspectives, M. Labatut, F. Lacan, C. Pradoux, J. Chmeleff, A. Radic, J. W. Murray, F. Poitrasson, Anne M. Johansen, F. Thil
Iron Sources And Dissolved-Particulate Interactions In The Seawater Of The Western Equatorial Pacific, Iron Isotope Perspectives, M. Labatut, F. Lacan, C. Pradoux, J. Chmeleff, A. Radic, J. W. Murray, F. Poitrasson, Anne M. Johansen, F. Thil
All Faculty Scholarship for the College of the Sciences
This work presents iron isotope data in the western equatorial Pacific. Marine aerosols and top core margin sediments display a slightly heavy Fe isotopic composition (δ56Fe) of 0.33 ± 0.11‰ (2SD) and 0.14 ± 0.07‰, respectively. Samples reflecting the influence of Papua New Guinea runoff (Sepik River and Rabaul volcano water) are characterized by crustal values. In seawater, Fe is mainly supplied in the particulate form and is found with a δ56Fe between −0.49 and 0.34 ± 0.07‰. The particulate Fe seems to be brought mainly by runoff and transported across continental shelves and slopes. …
The Interaction Between Arsenic And Struvite During Coprecipitation And Adsorption Processes, Ning Ma
The Interaction Between Arsenic And Struvite During Coprecipitation And Adsorption Processes, Ning Ma
Dissertations, Theses, and Capstone Projects
The formation of struvite, MgNH4PO4*6H2O (MAP), from wastes is one of the methods that can be used to recover P from wastes efficiently. However, since there are usually toxic components in the wastes, like arsenic (As), the possibility of having toxic contaminants in MAP is a big concern. So, the interaction between As and MAP during coprecipitation (CPT) and adsorption (ADS) processes were studied at pH 8-11. MAP precipitated without As at pH 8-11 was also characterized.
During CPT process, the MAP was precipitated from a MgCl2-(NH4)2HPO4-NaCl-H2O system spiked with As at an initial pH (pHi) of 8-11. The batch …
Noble Gases Identify The Mechanisms Of Fugitive Gas Contamination In Drinking-Water Wells Overlying The Marcellus And Barnett Shales, Thomas H. Darrah, Avner Vengosh, Robert B. Jackson, Nathaniel R. R. Warner, Robert J. Poreda
Noble Gases Identify The Mechanisms Of Fugitive Gas Contamination In Drinking-Water Wells Overlying The Marcellus And Barnett Shales, Thomas H. Darrah, Avner Vengosh, Robert B. Jackson, Nathaniel R. R. Warner, Robert J. Poreda
Dartmouth Scholarship
Horizontal drilling and hydraulic fracturing have enhanced energy production but raised concerns about drinking-water contamination and other environmental impacts. Identifying the sources and mechanisms of contamination can help improve the environmental and economic sustainability of shale-gas extraction. We analyzed 113 and 20 samples from drinking-water wells overlying the Marcellus and Barnett Shales, respectively, examining hydrocarbon abundance and isotopic compositions (e.g., C2H6/CH4, δ13C-CH4) and providing, to our knowledge, the first comprehensive analyses of noble gases and their isotopes (e.g., 4He, 20Ne, 36Ar) in groundwater near shale-gas wells. We addressed two questions. (i) Are elevated levels of hydrocarbon gases in …