Physical Sciences and Mathematics Commons^™

Dissolution-Driven Propulsion Of Floating Solids, Martin Chaigne, Michael Berhanu, Arshad Kudrolli

Physics

We show that unconstrained asymmetric dissolving solids floating in a fluid can move rectilinearly as a result of attached density currents which occur along their inclined surfaces. Solids in the form of boats composed of centimeter-scale sugar and salt slabs attached to a buoy are observed to move rapidly in water with speeds up to 5 mm/s determined by the inclination angle and orientation of the dissolving surfaces. While symmetric boats drift slowly, asymmetric boats are observed to accelerate rapidly along a line before reaching a terminal velocity when their drag matches the thrust generated by dissolution. By visualizing the …

Late Afternoon Seasonal Transition To Dissolution In A Coral Reef: An Early Warning Of A Net Dissolving Ecosystem?, Laura Stoltenberg, Kai G. Schulz, Coulson A. Lantz, Tyler Cyronak, Bradley D. Eyre

Marine & Environmental Sciences Faculty Articles

There are concerns that reefs will transition from net calcifying to net dissolving in the near future due to decreasing calcification and increasing dissolution rates. Here we present in situ rates of net ecosystem calcification (NEC) and net ecosystem production (NEP) on a coral reef flat using a slack-water approach. Up until dusk, the reef was net calcifying in most months but shifted to net dissolution in austral summer, coinciding with high respiration rates and a lower aragonite saturation state (Ω_arag). The estimated sediment contribution to NEC ranged from 8 – 21 % during the day and 45 …

Using Carbon Isotope Fractionation To Constrain The Extent Of Methane Dissolution Into The Water Column Surrounding A Natural Hydrocarbon Gas Seep In The Northern Gulf Of Mexico, M. Leonte, B. Wang, Scott A. Socolofsky, John A. Breier, John D. Kessler

School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations

A gas bubble seep located in the northern Gulf of Mexico was investigated over several days to determine whether changes in the stable carbon isotopic ratio of methane can be used as a tracer for methane dissolution through the water column. Gas bubble and water samples were collected at the seafloor and throughout the water column for isotopic ratio analysis of methane. Our results show that changes in methane isotopic ratios are consistent with laboratory experiments that measured the isotopic fractionation from methane dissolution. A Rayleigh isotope model was applied to the isotope data to determine the fraction of methane …

Salt Dissolution And Surface Subsidence In Central Kansas: A Seismic Investigation Of The Anthropogenic And Natural Origin Models, Neil Lennart Anderson, Alex A. Martinez, John F. Hopkins, Timothy R. Carr

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Gradual subsidence in the Punkin Center study area, northeast Reno County, Kansas, has resulted in ponding of surface waters, abandonment of at least one oil well, and damage to county roads. Because the Punkin Center area is within the Burrton oil field and is underlain by the Hutchinson Salt Member, surface subsidence historically has been attributed to salt dissolution of anthropogenic origin. Subsidence that occurred significant distances from any known well sites has been attributed to unrecorded abandoned wells or complex asymmetric patterns of salt dissolution that originated at a drillhole.

To ascertain the validity of the widely accepted anthropogenic …

Mercury Sulfide Dissolution In Environmental Conditions: Thermodynamic And Kinetic Approaches, Ping Jiang

FIU Electronic Theses and Dissertations

Mercury (Hg) is a global contaminant of ecosystems and human health risk, with complicated biogeochemical processes. Mercury sulfide (HgS) dissolution has been suggested as a key process in Hg cycling, as it could potentially increase the pool of inorganic Hg (iHg) for the production of methylmercury (MeHg). Despite previous sporadic observations of enhanced HgS dissolution under certain conditions, much remains unclear on mechanisms of HgS dissolution. The objective of my research was to advance the mechanistic understanding of HgS dissolution, concerning re-adsorption of released Hg, effects of thiol-ligands, and Hg speciation.

Considering the lack of feasible techniques to differentiate dissolution …

Antagonistic Effects Of Ocean Acidification And Rising Sea Surface Temperature On The Dissolution Of Coral Reef Carbonate Sediments, Daniel Trnovsky, Laura Stoltenberg, Tyler Cyronak, Bradley D. Eyre

Marine & Environmental Sciences Faculty Articles

Increasing atmospheric CO₂ is raising sea surface temperature (SST) and increasing seawater CO₂ concentrations, resulting in a lower oceanic pH (ocean acidification; OA), which is expected to reduce the accretion of coral reef ecosystems. Although sediments comprise most of the calcium carbonate (CaCO₃) within coral reefs, no in situ studies have looked at the combined effects of increased SST and OA on the dissolution of coral reef CaCO₃ sediments. In situ benthic chamber incubations were used to measure dissolution rates in permeable CaCO₃ sands under future OA and SST scenarios in a coral reef …

Comparing Chemistry And Census-Based Estimates Of Net Ecosystem Calcification On A Rim Reef In Bermuda, Travis A. Courtney, Andreas J. Andersson, Nicholas R. Bates, Andrew R. Collins, Tyler Cyronak, Samantha J. De Putron, Bradley D. Eyre, Rebecca Garley, Eric J. Hochberg, Rodney Johnson, Sylvia Musielewicz, Tim J. Noyes, Christopher L. Sabine, Adrienne J. Sutton, Jessy Toncin, Aline Tribollet

Marine & Environmental Sciences Faculty Articles

Coral reef net ecosystem calcification (NEC) has decreased for many Caribbean reefs over recent decades primarily due to changes in benthic community composition. Chemistry-based approaches to calculate NEC utilize the drawdown of seawater total alkalinity (TA) combined with residence time to calculate an instantaneous measurement of NEC. Census-based approaches combine annual growth rates with benthic cover and reef structural complexity to estimate NEC occurring over annual timescales. Here, NEC was calculated for Hog Reef in Bermuda using both chemistry and census-based NEC techniques to compare the mass-balance generated by the two methods and identify the dominant biocalcifiers at Hog Reef. …

Effects Of Elevated Pco2 And Irradiance On Growth, Photosynthesis And Calcification In Halimeda Discoidea, K. E. Peach, M. S. Koch, Patricia Blackwelder

Marine & Environmental Sciences Faculty Articles

Ocean acidification (OA) effects on photophysiology and calcification were examined in Halimeda discoidea, a calcifying macroalga that produces tropical reef sediments. Photosynthetic parameters, including maximum photosynthetic rate (P_max), photosynthetic efficiency (α) and compensating irradiance (I_c) were determined in short-term assays on live thalli after a 10 d exposure to 4 levels of CO₂ partial pressures (pCO₂; 491, 653, 982 and 1201 µatm) under saturating (300 µmol photons m^-2 s^-1) and sub-saturating (90 µmol photons m^-2 s^-1) irradiance in an aquaria study. Morphology …

Magnetic Mineral Diagenesis In The River‐Dominated Inner Shelf Of The East China Sea, China, Can Ge, Weiguo Zhang, Chenyin Dong, Yan Dong, Jinyan Liu, Nguyen Thi Thu Hien, Huan Feng, Lizhong Yu

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

The inner shelf of the East China Sea is a river-dominated margin characterized by fine-grained mud deposits and a rapid sedimentation rate. Three short sediment cores (similar to 2.7m in length) were examined to characterize spatial variations in magnetic mineral diagenesis. The sediment cores were analyzed for sedimentation rates, magnetic properties, particle size distribution, organic carbon, and total sulfur content. The two more proximal cores with higher sedimentation rates (similar to 2.2cm/yr and similar to 0.96cm/yr) do not exhibit obvious effects of reductive dissolution of magnetite with increasing depth, which is consistent with their lower total sulfur content. The offshore …

Dependence Of Ice-Core Relative Trace-Element Concentration On Acidification, Bess G. Koffman, Michael J. Handley, Erich C. Osterberg, Mark L. Wells, Karl J. Kreutz

Dartmouth Scholarship

To assess the role of methodological differences on measured trace-element concentrations in ice cores, we developed an experiment to test the effects of acidification strength and time on dust dissolution using snow samples collected in West Antarctica and Alaska. We leached Antarctic samples for 3 months at room temperature using nitric acid at concentrations of 0.1, 1.0 and 10.0% (v/v). At selected intervals (20 min, 24 hours, 5 days, 14 days, 28 days, 56 days, 91 days) we analyzed 23 trace elements using inductively coupled plasma mass spectrometry. Concentrations of lithogenic elements scaled with acid strength and increased by 100–1380% …

The Impact Of Changing Surface Ocean Conditions On The Dissolution Of Aerosol Iron, Matthew P. Fishwick, Peter N. Sedwick, Maeve C. Lohan, Paul J. Worsfold, Kristen N. Buck, Thomas M. Church, Simon J. Ussher

OES Faculty Publications

The proportion of aerosol iron (Fe) that dissolves in seawater varies greatly and is dependent on aerosol composition and the physicochemical conditions of seawater, which may change depending on location or be altered by global environmental change. Aerosol and surface seawater samples were collected in the Sargasso Sea and used to investigate the impact of these changing conditions on aerosol Fe dissolution in seawater. Our data show that seawater temperature, pH, and oxygen concentration, within the range of current and projected future values, had no significant effect on the dissolution of aerosol Fe. However, the source and composition of aerosols …

High-Resolution Magnetic Susceptibility Measurements For Investigating Magnetic Mineral Formation During Microbial Mediated Iron Reduction, Estella A. Atekwana, Farag M. Mewafy, Gamal Z. Abdel Aal, D. Dale Werkema, Andre Revil, Lee D. Slater

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Disimilatory iron-reducing bacteria play an important role in the reduction of Fe(hydr)oxides and the production of secondary solid-iron mineral phases that can have magnetic properties. Magnetic susceptibility can therefore play an important role in identifying zones where microbial-mediated iron reduction is occurring. We investigated the magnetic susceptibility variations in a hydrocarbon-contaminated aquifer where methanogenesis and iron reduction are the main biogeochemical processes. Our objectives are to (1) determine the variability of magnetic susceptibility, (2) determine the hydrobiogeochemical controls on the magnetic susceptibility variability, and (3) evaluate the use of magnetic susceptibility as a viable technique for identifying zones where the …

Permeable Coral Reef Sediment Dissolution Driven By Elevated Pco2 And Pore Water Advection, Tyler Cyronak, Isaac R. Santos, Bradley D. Eyre

Marine & Environmental Sciences Faculty Articles

Ocean acidification (OA) is expected to drive the transition of coral reef ecosystems from net calcium carbonate (CaCO₃) precipitating to net dissolving within the next century. Although permeable sediments represent the largest reservoir of CaCO₃ in coral reefs, the dissolution of shallow CaCO₃ sands under future pCO₂ levels has not been measured under natural conditions. In situ, advective chamber incubations under elevated pCO₂ (~800 µatm) shifted the sediments from net precipitating to net dissolving. Pore water advection more than doubled dissolution rates (1.10 g CaCO₃ m⁻² d⁻¹) when compared to …

An Analysis Of Drug Dissolution In Vivo, David Mcdonnell

Doctoral

The testing of drug dissolution rates from solid dosage forms is a very important area of research within the pharmaceutical industry. The ability to produce drugs with a given dissolution rate will lead to improved performance in the treatment of patients and will be of economic benefit to the pharmaceutical industry. However, dissolution testing in laboratories, aimed at reflecting in-vivo conditions, can be both time consuming and costly. Currently, most simulations of drug dissolution take place in standardized USP (United States Pharmaceutical) apparatuses. A number of these apparatuses exist, and it is the aim of this thesis to analyse drug …

Inverse Modeling Of Btex Dissolution And Biodegradation At The Bemidji, Mn Crude-Oil Spill Site, Hedeff I. Essaid, Isabelle M. Cozzarelli, Robert P. Eganhouse, William N. Herkelrath, Barbara A. Bekins, Geoffrey N. Delin, Win Butler

United States Geological Survey: Staff Publications

The U.S. Geological Survey (USGS) solute transport and biodegradation code BIOMOC was used in conjunction with the USGS universal inverse modeling code UCODE to quantify field-scale hydrocarbon dissolution and biodegradation at the USGS Toxic Substances Hydrology Program crude-oil spill research site located near Bemidji, MN. This inverse modeling effort used the extensive historical data compiled at the Bemidji site from 1986 to 1997 and incorporated a multicomponent transport and biodegradation model. Inverse modeling was successful when coupled transport and degradation processes were incorporated into the model and a single dissolution rate coefficient was used for all BTEX components. Assuming a …

Experimental Diatom Dissolution And The Quantification Of Microfossil Preservation In Sediments, D. B. Ryves, S. Juggins, Sherilyn C. Fritz, R. W. Battarbee

Department of Earth and Atmospheric Sciences: Faculty Publications

Four laboratory experiments on fresh, modern diatoms collected from lakes in the Northern Great Plains of North America were carried out to assess the effects of dissolution on diatom abundance and composition. Marked differences in mean dissolution susceptibility exist between species, despite sometimes significant intra- specific variation between heterovalves. Twenty-four taxa were ranked according to susceptibility to dissolution using an exponential decay model of valve abundance. This dissolution ranking was used to derive two weighted indices of sample preservation. A third index (F) was based on a simple binary classification of valve morphology into dissolved and pristine categories, …

Measurements Of Salinity In The Coastal Ocean: A Review Of Requirements And Technologies, Catherine Woody, Eddie Shih, Jerry Miller, Thomas Royer, Larry P. Atkinson, Richard S. Moody

CCPO Publications

Salinity, a measure of the dissolved salts in seawater, is a fundamental property of seawater and basic to understanding biological and physical processes in coastal waters. In the open ocean long term salinity measurements are identified as necessary to understand global climate studies, hydrological cycle, and circulation. In the coastal oceans, information on salinity is critical to understanding biological effects on ecosystem function such as disease, nursery grounds, or harmful algal blooms and on physical processes such as freshwater runoff estuarine mixing, and coastal currents. While the importance of salinity is recognized, little attention has been given to making routine …

Concentrations And Isotope Ratios Of Dissolved Inorganic Carbon In Denitrifying Environments, C. Nascimento, Eliot A. Atekwana, R. V. Krishnamurthy

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

We measured the concentration and isotope ratio of dissolved inorganic carbon (DIC) in groundwater associated with denitrification (C_org + NO₃^- = CO₂ + N₂) in an agriculturally impacted site in southwestern Michigan. Samples with the lowest nitrate levels also had low dissolved oxygen content and were more depleted in δ¹³C than background groundwater. All the samples had DIC concentrations in excess of titratable alkalinity. The magnitude of this DIC in excess of alkalinity correlated with a decreasing δ¹³C attesting to the presence of CO₂ derived from organic carbon. Carbon …

An Overview Of Some Of The Large Scale Mechanisms Of Salt Dissolution In Western Canada, Neil Lennart Anderson, Ralph W. Knapp

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Well log and seismic data indicate that the bedded rock salts of the Devonian Prairie Formation were widely distributed and uniformly deposited in the Lloydminster area, Western Canada; however, as a result of extensive leaching, the distribution of these salts is not now what it once was. The Lloydminster area is now bisected by the north-south trending main dissolutional edge of the Prairie salt. Thick salt (up to 150 m) is preserved to the west of this edge; to the east the salt is mostly absent. The paper presents an overview of the envisioned principal mechanisms of salt dissolution. The …

Westhazel General Petroleums Pool: Case History Of A Salt- Dissolution Trap In West-Central Saskatchewan, Canada, Neil Lennart Anderson, Dale A. Cederwall

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

The Westhazel General Petroleums (GP) Pool of west-central Saskatchewan, Canada, produces from the GP member of the Lower Cretaceous Mannville Group. This reservoir is structurally closed across the updip, eastern dissolutional edge of the underlying Middle Devonian rock salt of the Leofnard Member, Prairie Formation. The leaching of these salts occurred in post-Mannville time in the Westhazel area and caused the regional southwest dip of the General Petroleums member to be locally reversed.The Westhazel GP Pool, from a geophysical perspective, is characteristic of many of the shallow Lower Cretaceous pools situated along the dissolutional edge of the Prairie salt. The …

Transport Modeling – Technical And Legal Issues, Adrian Brown

Uncovering the Hidden Resource: Groundwater Law, Hydrology, and Policy in the 1990s (Summer Conference, June 15-17)

27 pages.

Contains footnotes.

A Seismic Analysis Of Black Creek And Wabumun Salt Collapse Features, Western Canadian Sedimentary Basin, Neil Lennart Anderson, Robert James Sidford Brown

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

These salt remnants and their associated collapse features are often associated with structural or stratigraphic traps. As a result of the relationships between dissolution and hydrocarbon entrapment, the distribution (areal extent and thickness) of these salt remnants is of significant interest to the explorationist. Seismic information about the thickness and the extent of these salts should be used together with well log control to generate subsurface distribution maps. These maps will facilitate both the delineation of prospective structural and stratigraphic play fairways and the determination of the timing of salt dissolution. In addition, an appreciation of regional salt distribution will …