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Central Washington University

2006

Articles 1 - 10 of 10

Full-Text Articles in Physical Sciences and Mathematics

Perchlorate And Nitrate Remediation Efficiency And Microbial Diversity In A Containerized Wetland Bioreactor, Paula Krauter, Bill Daily Jr., Valerie Dibley, Holly Pinkart, Tina Legler Aug 2006

Perchlorate And Nitrate Remediation Efficiency And Microbial Diversity In A Containerized Wetland Bioreactor, Paula Krauter, Bill Daily Jr., Valerie Dibley, Holly Pinkart, Tina Legler

All Faculty Scholarship for the College of the Sciences

We have developed a method to remove perchlorate (14–27 μg/L) and nitrate (48 mg/L) from contaminated groundwater using a wetland bioreactor. The bioreactor has operated continuously in a remote field location for more than 2 yr with a stable ecosystem of indigenous organisms. This study assesses the bioreactor for long-term perchlorate and nitrate remediation by evaluating influent and effluent groundwater for oxidation-reduction conditions and nitrate and perchlorate concentrations. Total community DNA was extracted and purified from 10-g sediment samples retrieved from vertical coring of the bioreactor during winter. Analysis by denaturing gradient gel electrophoresis of short, 16S rDNA, polymerase-chain-reaction products …

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Photoreductive Dissolution Of Ferrihydrite By Methanesulfinic Acid: Evidence Of A Direct Link Between Dimethylsulfide And Iron-Bioavailability, Anne M. Johansen, Jennifer M. Key Jul 2006

Photoreductive Dissolution Of Ferrihydrite By Methanesulfinic Acid: Evidence Of A Direct Link Between Dimethylsulfide And Iron-Bioavailability, Anne M. Johansen, Jennifer M. Key

All Faculty Scholarship for the College of the Sciences

Within open‐ocean regions where excess macronutrients are present, phytoplankton growth is limited by the bioavailability of iron supplied to these areas primarily within atmospheric aerosols of crustal origin. However, processes that control the abundance of biologically accessible iron in these aerosols are largely unknown. Here we show that dissolution of ferrihydrite, a surrogate iron(oxy)hydroxide phase found in atmospheric waters, is enhanced in the presence of methanesulfinic acid (MSIA, CH3SO2H, a dimethylsulfide (DMS) oxidation intermediate) in laboratory irradiation experiments with aqueous suspensions that simulate marine aerosol particles. The increased release of soluble Fe(II) is attributed to a …

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Carrier Dynamics In Α‐Fe2o3 (0001) Thin Films And Single Crystals Probed By Femtosecond Transient Absorption And Reflectivity, Alan G. Joly, Joshua R. Williams, Scott A. Chambers, Gang Xiong, Wayne P. Hess, David M. Laman Mar 2006

Carrier Dynamics In Α‐Fe2o3 (0001) Thin Films And Single Crystals Probed By Femtosecond Transient Absorption And Reflectivity, Alan G. Joly, Joshua R. Williams, Scott A. Chambers, Gang Xiong, Wayne P. Hess, David M. Laman

All Faculty Scholarship for the College of the Sciences

Femtosecond transient reflectivity and absorption are used to measure the carrier lifetimes in α‐Fe2O3 thin films and single crystals. The results from the thin films show that initially excited hot electrons relax to the band edge within 300 fs and then recombine with holes or trap within 5 ps. The trapped electrons have a lifetime of hundreds of picoseconds. Transient reflectivity measurements from hematite (α‐Fe2O3)single crystals show similar but slightly faster dynamics leading to the conclusion that the short carrier lifetimes in these materials are due primarily to trapping to Fe d- …

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Serial Ruptures Of The San Andreas Fault, Carrizo Plain, California, Revealed By Three-Dimensional Excavations, Jing Liu-Zeng, Yann Klinger, Kerry Sieh, Charles Rubin, Gordon Seitz Feb 2006

Serial Ruptures Of The San Andreas Fault, Carrizo Plain, California, Revealed By Three-Dimensional Excavations, Jing Liu-Zeng, Yann Klinger, Kerry Sieh, Charles Rubin, Gordon Seitz

All Faculty Scholarship for the College of the Sciences

It is poorly known if fault slip repeats regularly through many earthquake cycles. Well‐documented measurements of successive slips rarely span more than three earthquake cycles. In this paper, we present evidence of six sequential offsets across the San Andreas fault at a site in the Carrizo Plain, using stream channels as piercing lines. We opened a latticework of trenches across the offset channels on both sides of the fault to expose their subsurface stratigraphy. We can correlate the channels across the fault on the basis of their elevations, shapes, stratigraphy, and ages. The three‐dimensional excavations allow us to locate accurately …

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Geochronology And Tectonic Significance Of Middle Proterozoic Granitic Orthogneiss, North Qaidam Hp/Uhp Terrane, Western China, Chris G. Mattinson, Joseph L. Wooden, Juhn G. Liou, D. K. Bird, C. L. Wu Jan 2006

Geochronology And Tectonic Significance Of Middle Proterozoic Granitic Orthogneiss, North Qaidam Hp/Uhp Terrane, Western China, Chris G. Mattinson, Joseph L. Wooden, Juhn G. Liou, D. K. Bird, C. L. Wu

All Faculty Scholarship for the College of the Sciences

Amphibolite-facies para- and orthogneisses near Dulan, in the southeast part of the North Qaidam terrane, enclose minor ultra-high pressure (UHP) eclogite and peridotite. Field relations and coesite inclusions in zircons from paragneiss suggest that felsic, mafic, and ultramafic rocks all experienced UHP metamorphism and a common amphibolite-facies retrogression. Ion microprobe U–Pb and REE analyses of zircons from two granitic orthogneisses indicate magmatic crystallization at 927 ± Ma and 921 ± 7 Ma. Zircon rims in one of these samples yield younger ages (397–618 Ma) compatible with partial zircon recrystallization during in-situ Ordovician-Silurian eclogite-facies metamorphism previously determined from eclogite and paragneiss …

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Pyritized Tube Feet In A Protasterid Ophiuroid From The Upper Ordovician Of Kentucky, U.S.A., Alexander Glass Jan 2006

Pyritized Tube Feet In A Protasterid Ophiuroid From The Upper Ordovician Of Kentucky, U.S.A., Alexander Glass

All Faculty Scholarship for the College of the Sciences

A single specimen of the protasterid ophiuroid Protasterina flexuosa from the Kope Formation (Cincinnatian, Upper Ordovician) of Kentucky exhibits three−dimensionally pyritized tube feet. This represents the first report of soft−tissue preservation in an echinoderm from the type−Cincinnatian series. The tube feet are solid and lack all internal structure. They consist of aggregated masses of small euhedral to subhedral pyrite crystals suggesting that pyritization, although decay−induced and mediated, did not necessarily replicate soft−tissues but might instead have formed inside the void−spaces left behind during the decay process. The discovery of pyritized soft−tissue as delicate as ophiuroid tube feet suggests that similar …

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Writing Projective Representations Over Subfields, Stephen P. Glasby, C. R. Leedham-Green, E. A. O'Brien Jan 2006

Writing Projective Representations Over Subfields, Stephen P. Glasby, C. R. Leedham-Green, E. A. O'Brien

All Faculty Scholarship for the College of the Sciences

Let G=〈X〉be an absolutely irreducible subgroup of GL(d, K), and let F be a proper subfield of the finite field K. We present a practical algorithm to decide constructively whether or not G is conjugate to a subgroup of GL(d, F).K×, where K× denotes the centre of GL(d, K). If the derived group of G also acts absolutely irreducibly, then the algorithm is Las Vegas and costs O(|X|d3+d2log|F|) arithmetic operations in K. This work forms part of a recognition project based on Aschbacher’s classification of maximal subgroups of GL(d, K).

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Historical Glacier And Climate Fluctuations At Mount Hood, Oregon, Karl Lillquist, Karen Walker Jan 2006

Historical Glacier And Climate Fluctuations At Mount Hood, Oregon, Karl Lillquist, Karen Walker

Geography Faculty Scholarship

Terminus fluctuations of five glaciers and the correspondence of these fluctuations to temperature and precipitation patterns were assessed at Oregon's Mount Hood over the period 1901–2001. Historical photographs, descriptions, and climate data, combined with contemporary GPS measurements and GIS analysis, revealed that each glacier experienced overall retreat, ranging from −62 m at the Newton Clark Glacier to −1102 m at the Ladd Glacier. Within this overall trend, Mount Hood's glaciers experienced two periods each of retreat and advance. Glaciers retreated between 1901 and 1946 in response to rising temperatures and declining precipitation. A mid-century cool, wet period led to glacier …

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Fluvial Response To Intra-Canyon Lava Flows, Owyhee River, Southeastern Oregon, Cooper Cooke Brossy Jan 2006

Fluvial Response To Intra-Canyon Lava Flows, Owyhee River, Southeastern Oregon, Cooper Cooke Brossy

All Master's Theses

At least six lava flows have entered the Owyhee River Canyon north of Rome, Oregon, since the Pliocene and directly impacted the Owyhee River. The effects on the river of the two youngest lava flows, the West Crater (60–80 ka) and Saddle Butte (> 60–90 ka), are readily apparent. These two lava flows entered a paleo-Owyhee Canyon several kilometers wide via three different tributary drainages. The flows dammed the Owyhee River, created lakes, and effectively confined the river to the opposite side of the valley from the flows’ entrance. Lava from these flows filled a paleo-Owyhee Canyon to depths of …

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Deciphering The Signature Of Magma Mixing: Examples From The Castle Creek Eruptive Period, Mount St. Helens, Washington, Seth Taylor Mattos Jan 2006

Deciphering The Signature Of Magma Mixing: Examples From The Castle Creek Eruptive Period, Mount St. Helens, Washington, Seth Taylor Mattos

All Master's Theses

Mount St. Helens (MSH) volcano in southwestern Washington has intermittently erupted dacitic products for the last 40,000 years. On limited occasions, the volcano has produced andesite lava flows, and during one short-lived period, basaltic lava flows. This time interval has been termed the Castle Creek eruptive period and occurred between approximately 2500 and 1700 years B.P. The Castle Creek period erupted dacite, andesite and basalt within this short span of time. Andesite and dacite eruptions dominate the first approximately 700 years of the period, and all basaltic units were erupted in approximately the last 100 years of the period. This …

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