Barry R. Bickmore

Brigham Young University - Provo Main Campus | BYU · Department of Geological Sciences

Lakes are invaluable archives of past ecosystem changes, and this study focuses on one of the largest freshwater lakes in the western US. At 380 km², Utah Lake is the third-largest freshwater lake in the USA west of the Mississippi River. Adjacent to an urban corridor, it is an important resource for surrounding communities as well as being impacte...

The use of inorganic phosphate sources (IPS) has declined, prompting feed manufacturers to utilize other ingredients to maintain production rates. AZOMITE® (AZM) can be supplemented in diets to improve production rate, reduce motor load, and decrease electrical use of the pellet mill. AZOMITE® is composed of fine and coarse fractions, but the mecha...

Glaciers alter the geochemistry of sensitive alpine streams by exposing freshly weathered bedrock and releasing atmospherically deposited trace metals from melting ice. Changes in the timing and quantity of glacial melt also affect discharge and temperature of alpine streams. To investigate the effects of glacier meltwater on the geochemistry and h...

Atmospheric deposition to urban areas and mountain snowpack often contains a mixture of playa dust and anthropogenic aerosols, yet the relative contribution of trace elements from each source is not well understood. To evaluate dust contributions from regional playas to an urban area, we sampled playa dust sources, urban dust deposition, and snow d...

Lakes worldwide are impacted by eutrophication and harmful algal or cyanobacteria blooms (HABs) due to excessive nutrients, including legacy P released from sediments in shallow lakes. Utah Lake (northern Utah, USA) is a shallow lake with urban development primarily on the east side of the watershed, providing an opportunity to evaluate HABs in rel...

Representative XRD pattern for Utah Lake sediment showing prominent quartz and calcite peaks. This pattern is for sample 3-D collected in November 2016. The height of the mineral peaks represents the abundance of minerals present in the sample. (TIF)

Sediment total P concentrations measured after sample digestion. (XLSX)

Sediment chemistry and mineralogy. (XLSX)

Pore water chemistry. (XLSX)

Water column chemistry. (XLSX)

Sampling sites for cyanobacteria cell count data shown in Fig 6. (TIF)

Sediment sequential extraction data. (XLSX)

Groundwater resources can be impacted by contamination from geogenic and anthropogenic inputs but it can be difficult to disentangle contaminant sources. In this study, we investigated the sources and distribution of NO3 and As in Goshen Valley, UT, a semi-arid alluvial basin in the western USA that contains geothermal waters, playa soils, agricult...

Much of the world's population lives in developing countries in regions with deeply weathered soils and thick, subjacent saprolites. These areas are widespread in the tropics and compose an important component of the critical zone (CZ). The Hawaiian Islands (USA) make an excellent natural laboratory for examining the tropical CZ, where the bedrock...

The relationship between bond valence and structural energy has never been fully explored, although several predictive models have assumed some simple relationship between the two. Some of these models relate energy only to bond valence, while others also take into account other factors, such as bond character. We examined periodic trends in bond d...

The enigmatic and unexpected occurrence of coarse crystalline (gray) hematite spherules at Terra Meridiani on Mars in association with deposits of jarosite-rich sediments fueled a variety of hypotheses to explain their origin. In this study, we tested the hypothesis that freezing of aqueous hematite nanoparticle suspensions, possibly produced from...

Here we test the concept that a potential energy model (force field) based on an expansion of the bond-valence model can use molecular geometry to make a reasonable prediction of the thermodynamic energy. The backbone of the model is a non-standard choice of structural descriptors for the energy decomposition, which relates the energy to particular...

The bond-valence model has recently been expanded to include a directional component, the vectorial bond-valence sum, which is useful for characterizing non-centrosymmetric distortions involving lone-pair and second-order Jahn-Teller effects. Here we show that the bond-valence sum and vectorial bond-valence sum are equivalent to monopole and dipole...

The mean, trend and variability of net snow accumulation in firn cores are often used to validate model output, develop remote-sensing algorithms and quantify ice-sheet surface mass balance. Thus, accurately defining uncertainties associated with these in situ measurements is critical. In this study, we apply statistical simulation methods to quant...

The bond-valence model (BVM) posits an inverse relationship between bond valence (essentially bond order) and bond length, typically described by either exponential or power-law equations. To assess the value of these forms for describing a wider range of bond lengths than found in crystals, we first assume that the bond critical point density (ρb,...

The bond-valence model has, for several decades, been widely used for creating quantitative structure-activity relationships (QSARs), crystal structure modeling, and verification of proposed structures. Certain limitations of the model, such as the neglect of interactions between cations and between anions, have prevented it from being more broadly...

We originally wrote a version of this essay for use in introductory college science courses to address a number of prevalent issues with teaching the nature of science and how it relates to religion. Students commonly develop a simplistic view of science as “just the facts,” which can lead to a tendency to dismiss scientific conclusions that challe...

While simple models of the Earth’s ocean can provide useful information about the sensitivity of the climate to increasing greenhouse gases, it is important to ensure that the models are based on realistic physical processes and are evaluated with an accurate numerical methodology. In this regard, a number of computational issues are identified and...

Formation of Mars analog hematite spherules through freezing likely requires nanometric platy hematite and slow ice crystallization.

There have been a number of attempts to relate structural descriptors based on the bond-valence theory to the Brønsted acidity of (hydr)oxyacid monomers and oxide surface functional groups, via simple quantitative structure-activity relationships (QSARs). These models show some promise, but since they have been calibrated solely on monomers, it is...

Slip during large earthquakes occurs along faults that are hundreds of kilometers long, yet the dynamic weakening that drives these earthquakes is controlled by nano- to micro-scale frictional processes. We analyzed these processes along experimental faults that slipped at rates approaching seismic velocity, and which displayed intense dynamic weak...

The vectorial bond-valence model (VBVM) describes the spatial distribution of bonds to each atom in a system in terms of the vector sum of the incident bond valences. It has been applied in the past to cations not subject to electronic structure effects (e.g., lone-pair or Jahn-Teller effects) in which case the expectation is that the vector sum wi...

Typically, rock friction is measured on experimental samples that are a few cm to one m in size, while molecular-dynamic simulate friction at the nano-scale. We present here preliminary results of rock friction on tens-of-micron scale in the gap between the above scales. The analysis was conducted with the Atomic Force Microscope (AFM) instrument....

The coefficient of friction of clay minerals at the micro-scale has generally not been studied due to difficulties in obtaining measurements in a bulk-soil volume undergoing shear at such small scales. Information on friction at the micro-scale may provide insight into grain-scale processes that operate in bulk samples or in natural faults. The obj...

Here we describe a method for teaching the NOS called "Science as Storytelling", which was designed to directly confront naive realist preconceptions about the NOS and replace them with more sophisticated ideas, while retaining a moderate realist perspective. It was also designed to foster a more sophisticated understanding of the science-religion...

Gd(III) and Cm(III) sorption onto a pure aluminum hydroxide, gibbsite (α-Al(OH)3), is studied by batch experiments and time-resolved laser fluorescence spectroscopy (TRLFS). The experiments are conducted under argon atmosphere to exclude the influence of atmospheric CO2 on solution and surface speciation. Batch experiments are done in two different...

The recent controversy about the structure of liquid water pits a new model involving water molecules in relatively stable "rings-and-chains" structures against the standard model that posits water molecules in distorted tetrahedral coordination. Molecular dynamics (MD) simulations, both classical and ab initio, almost uniformly support the standar...

Cm(III) Gd(III) Gibbsite (α-Al(OH) 3) Sorption TRLFS Surface complexation Incorporation Gd(III) and Cm(III) sorption onto a pure aluminum hydroxide, gibbsite (α-Al(OH) 3), is studied by batch experiments and time-resolved laser fluorescence spectroscopy (TRLFS). The experiments are conducted under argon atmosphere to exclude the influence of atmosp...

Cm(III) Gd(III) Gibbsite (α-Al(OH) 3) Sorption TRLFS Surface complexation Incorporation Gd(III) and Cm(III) sorption onto a pure aluminum hydroxide, gibbsite (α-Al(OH) 3), is studied by batch experiments and time-resolved laser fluorescence spectroscopy (TRLFS). The experiments are conducted under argon atmosphere to exclude the influence of atmosp...

In light of recent work on the reactivity of specific sites on large (hydr)oxo-molecules and the evolution of surface topography during dissolution, we examined the ability to extract molecular-scale reaction pathways from macroscopic dissolution and surface charge measurements of powdered minerals using an approach that involved regression of mult...

Science instruction in elementary school classrooms is frequently lacking in the United States. One factor that impacts the amount and quality of science instruction is teacher attitudes toward science. The Earth Science Mini-Lesson Project is a strategic program created to help improve preservice elementary school teachers' attitudes toward scienc...

It has been shown here that the standard formulation of the MUSIC model does not deliver the molecular-scale insight into oxide surface reactions that it promises. The model does not properly divide long-range electrostatic and short-range contributions to acid-base reaction energies, and it does not treat solvation in a physically realistic manner...

In a previous contribution, we outlined a method for predicting (hydr)oxy-acid and oxide surface acidity constants based on three main factors: bond valence, Me O bond ionicity, and molecular shape. Here, electrostatics calculations and ab initio molecular dynamics simulations are used to qualitatively show that Me O bond ionicity controls the exte...

The influence of Al(OH)4− on the dissolution rate of quartz at pH 10–13 and 59–89 °C was determined using batch experiments. Al(OH)4− at concentrations below gibbsite solubility depressed the dissolution rate by as much as 85%, and this effect was greater at lower pH and higher Al(OH)4− concentration. Dissolution rates increased with increasing tem...

The Earth Science Storybook Project is being conducted with Brigham Young University's (BYU) Physical Science 110B (PS 110B) class, which is introductory geology for Elementary Education majors. Under the project, preservice elementary teachers in PS 110B are mentored by university geology faculty and geology graduate students as they author childr...

Here we use gibbsite as a model system with which to test a recently published, bond-valence method for predicting intrinsic pKa values for surface functional groups on oxides. At issue is whether the method is adequate when valence parameters for the functional groups are derived from ab initio structure optimization of surfaces terminated by vacu...

Bond-valence methods for the prediction of (hydr)oxide solution monomer and surface functional group acidity constants are examined in light of molecular structures calculated using ab initio methods. A new method is presented that is based on these calculated structures, and it is shown that previously published methods have neglected one or more...

The atomic structure of dioctahedral 2:1 phyllosilicate edge surfaces was calculated using pseudopotential planewave density functional theory. Bulk structures of pyrophyllite and ferripyrophyllite were optimized using periodic boundary conditions, after which crystal chemical methods were used to obtain initial terminations for ideal (110)- and (0...

A suite of macros for the freeware image analysis program, Image SXM, are described. These macros are designed to measure the perimeter, horizontal area, and volume of discrete features in AFM images, obtaining accurate and consistent estimates. Directions for using the software and example applications are also given. Such tools allow one to perfo...

The atomic structure of dioctahedral 2:1 phyllosilicate edge surfaces was predicted using pseudopotential planewave density functional theory calculations. Ideal (110) and (010) type neutral edge surfaces of pyrophyllite and ferripyrophyllite were considered. Bulk structures of pyrophyllite and ferripyrophyllite were optimized using periodic bounda...

Rapid and accurate determination of the surface area of three kaolinite clay standards, taking into account the complex microtopography of the particles, was achieved using atomic force microscopy images and computerized image analysis. All surface areas were determined to within 3%. Edge surface area is 18.2–30.0% of the total surface area dependi...

Caustic NaNO3 solutions containing dissolved Al were reacted with quartz sand at 89 degrees C to simulate possible reactions between leaked nuclear waste and primary subsurface minerals at the U.S. Department of Energy's Hanford site in Washington. Nitrate-cancrinite began to precipitate onto the quartz after 2-10 days, cementing the grains togethe...

The dissolution behavior of two smectite minerals, hectorite (trioctahedral) and nontronite (dioctahedral), was observed in situ, in acid solutions, using atomic force microscopy. As expected, the crystallites dissolved inward from the edges, and the basal surfaces appeared to be unreactive during the timescale of the experiments. The hectorite (01...

Christianity as a whole is a historical religion. That is, its truth claims are based on the historical reality of certain events, such as the resurrection of Jesus Christ. In addition, each Christian denomination is bound to a particular view or range of views of Christian history that tie into its reason for existence. These views range from dire...

The dissolution of individual hectorite (a trioctahedral smectite) particles has been observed at molecular scales in acidic aqueous solution with atomic force microscopy (AFM). A new sample preparation technique was used to attach nanometer-sized hectorite particles to a mica substrate. The reactive surface area of individual hectorite particles w...

Three methods were developed that allow for the imaging of any clay mineral in aqueous solutions with atomic force microscopy (AFM). The methods involve fixing the particles onto special substrates that do not complicate the imaging process, but hold the particles sufficiently so that they do not move laterally or float away during imaging. Two tec...

The public domain image analysis program NIH Image (http://rsb.info.nih.gov/nih-image) has been modified and extended to produce Image SXM (http://reg.ssci.liv.ac.uk), a program that supports many of the image file formats used by various scanning probe microscope manufacturers. This article discusses the different approaches to software customizat...

The public domain image analysis program NIH Image (http://rsb.info.nih.gov/nih-image) has been modified and extended to produce Image SXM (http://reg.ssci.liv.ac.uk), a program that supports many of the image file formats used by various SPM manufacturers. This article discusses the different approaches to software customisation and describes the...

Long-term studies in new areas of geochemical research that would not be possible without scanning probe microscopes are now well underway. Several examples are given in this chapter, including atomic force microscopy-based research that shows 1) that the rate of aqueous dissolution at specific reactive sites is slower in the presence of a thin wat...