Physical Sciences and Mathematics Commons^™

Geophysical And Hydrological Evaluation Of Two Bog Complexes In A Northern Peatland: Implications For The Distribution Of Biogenic Gases At The Basin Scale, Xavier Comas, Lee Slater, Andrew S. Reeve

Earth Science Faculty Scholarship

Ground penetrating radar (GPR) was used to determine peat basin geometry and the spatial distribution of free-phase biogenic gasses in two separate units of a northern peatland (Central and Southern Unit of Caribou Bog, Maine). The Central Unit is characterized by a deep basin structure (15 m maximum depth) and a raised (eccentric) bog topographic profile (up to 2 m topographic variation). Here numerous regions of electromagnetic (EM) wave scattering are considered diagnostic of the presence of extensive free-phase biogenic gas. In contrast, the Southern Unit is shallower (8 m maximum depth) and has a slightly convex upwards bog profile …

Icesat Measurements Reveal Complex Pattern Of Elevation Changes On Siple Coast Ice Streams, Antarctica, B. Csatho, Y. Ahn, T. Yoon, C. J. Van Der Veen, S. Vogel, Gordon S. Hamilton, D. Morse, B. Smith, V. Blue Spikes

Earth Science Faculty Scholarship

We compare ICESat data (2003-2004) to airborne laser altimetry data (1997-98 and 1999-2000) to monitor surface changes over portions of Van der Veen (VdVIS), Whillans (WIS) and Kamb ice streams (KIS) in the Ross Embayment of the West Antarctic Ice Sheet. The spatial pattern of detected surface changes is generally consistent with earlier observations. However, important changes have occurred during the past decade. For example, areas on the VdVIS and WIS, where large thinning was detected by the airborne surveys, are now closer to being in balance. The upper trunk of KIS continues to build up with thickening rates reaching …

Minerva 2005, The Honors College

Minerva

This issue of Minerva includes an article on the development of HON 170: Currents & Contexts; a discussion of the Honors College's "Last Lecture Series;" a reflection on the legacy of former Honors Program Director, Robert Thomson; and an article on the visual art found around the Honors College complex.

A Microreactor System For Measuring Size Selectivity In Porous Wo3 Sensor Materials, Meng Lu

Electronic Theses and Dissertations

Our interest in studying reactions catalyzed by high surface area W0₃ powders is based on their potential application as the active material in sensors for low level (ppb) detection of flammable or toxic gases. A series of porous W0₃ powders with both meso- and micro-porosity have been synthesized by Waghe and Tripp. Preliminary results of the response of sensors fabricated from these materials indicated the possibility of size selectivity on the molecular scale. To provide support for the hypothesis of size selectivity and understand the reaction kinetics of alcohols over the new porous W0₃ powders for sensor …

Collaborative Research: Toward Environmental Genomics: Can We Estimate Bacterial Diversity In The Ocean?, Daniel L. Distel

University of Maine Office of Research Administration: Grant Reports

Environmental genomics, wherein the total genomic diversity of a natural community may be sampled and analyzed in an ecological context, remains an elusive goal. This is due, at least in part, to (I) a lack of reliable estimates of total community diversity and (II) a lack of information regarding the exact phylogenetic, genomic and ecological units measured by commonly used diversity estimators. Although ribosomal RNA approaches have provided the first steps towards diversity estimation, and are widely used as a proxy for unique bacterial types in natural populations, the genomic unit a ribotype measures remains largely unexplored. It is generally …

Paleoclimate From Mount Everest Ice Cores, Paul Mayewski

University of Maine Office of Research Administration: Grant Reports

The primary goal of this research is to analyze three ice cores collected by a joint Chinese-US team of researchers in the spring of 2001. At that time, a 117-meter ice core was recovered from the East Rongbuk (ERC) glacier at 6500 meters above sea level. In addition to these analyses, the researchers will participate in a joint Chinese-US expedition to the region to retrieve modern day glaciological and meteorological data to aid in the interpretation of the ice core data.

Based on local accumulation rates and layer thinning estimates, the new 117-meter ERC core likely represents at least several …

Theoretical Derivation Of The Depth Average Of Remotely Sensed Optical Parameters, J. Ronald V. Zaneveld, Andrew H. Barnard, Emmanuel Boss

Marine Sciences Faculty Scholarship

The dependence of the reflectance at the surface on the vertical structure of optical parameters is derived from first principles. It is shown that the depth dependence is a function of the derivative of the round trip attenuation of the downwelling and backscattered light. Previously the depth dependence was usually modeled as being dependent on the round trip attenuation. Using the new relationship one can calculate the contribution of the mixed layer to the overall reflectance at the surface. This allows one to determine whether or not to ignore the vertical structure at greater depth. It is shown that the …

Lake-Level Influences On Chironomid-Based Reconstructions Of Paleotemperature, Ann Dieffenbacher-Krall

University of Maine Office of Research Administration: Grant Reports

This award is for support of a study to determine the influence of lake-level changes on chironomid-based temperature estimates. A transect of cores from within each of two lakes in northern Maine will be examined for evidence of past water levels. Chironomid analysis will be performed on cores from both lakes. Geologic/chronologic evidence of Younger Dryas-age ice readvance in northern Maine will provide the data necessary to apply a well-developed glaciological model to determine the range of temperature and precipitation that could possibly have prevailed during this period. Chironomid estimates of temperature will be reconciled with the temperature range derived …

Workshop On U.S.-Hungarian Research Collaboration To Address It Challenges For 21st Century Society, Anthony Stefanidis

University of Maine Office of Research Administration: Grant Reports

This collaborative grant workshop lays a foundation for building joint US-Hungarian research projects. The proposed set of activities is an outgrowth of ongoing discussions between NSF program managers and Hungarian Research Scientists visiting NSF in the Fall of 2002. These discussions culminated in Hungarian researchers attending and participating in the annual meeting of digital government PI's and their government agency partners in May 2003 (dgo2003). Two US researchers who organized an International Digital Government Research Collaborations panel at dgo2003, in discussion with the Hungarian participants, accepted an invitation by the Hungarians to organize a small group of US researchers to …

Aquaculture-Based Calibration Of The M.Edulis Isotope Paleothermometer, Karl J. Kreutz, Harold Borns, Douglas Introne, Bruce Barber, Sven Funder

University of Maine Office of Research Administration: Grant Reports

Oxygen isotopic analysis of marine carbonate shells (δ¹⁸O_c) is a standard paleoceanographic technique used to document the chronology of seawater temperature change. Shell δ¹⁸O_c depends not only upon seawater temperature, but also upon the isotopic composition of the seawater (δ¹⁸O_w; related to salinity) and any species-specific fractionation that occurs during biomineralization. In the past, the interpretation of shell δ¹⁸O_c has been based upon theoretical studies of chemical equilibrium and kinetics, or laboratory experiments involving the inorganic precipitation of CaCO₃ from solution. Other methods have employed …

Acquisition Of A High Resolution Icp-Ms For Environmental Research And Training In Maine, Karl J. Kreutz

University of Maine Office of Research Administration: Grant Reports

This award provides support to significantly enhance the elemental and isotopic analysis capabilities at the University of Maine through the acquisition of a high resolution inductively coupled plasma mass spectrometer (HR-ICP-MS). The HR-ICP-MS will enable environmental scientists and students at UMaine, as well as other educational institutions and state agencies, to substantially broaden their interdisciplinary research interests far beyond the current possibilities. Specifically, a state-of-the-art HR-ICP-MS will enable the PIs to: 1) Dramatically expand our element concentration and element ratio analysis capabilities in aqueous matrices. Existing UMaine research strengths in Quaternary science, environmental geochemistry, and marine biogeochemistry rely upon accurate …

Us Itase Glaciochemistry, Paul Mayewski

University of Maine Office of Research Administration: Grant Reports

The UMaine Continuous ice core Melter (UMCoM) system is a modified Wagenbach-style continuous melter system (Rothlisberger et al., 2000) with three important differences. First, we have constructed the melthead as two separate pieces, a base and a melter plate, so that it can be easily dismantled and cleaned between melting sessions. Second, the melter plate in contact with the ice is composed of pure nickel (>99.9% Ni) so that trace element measurements can be made from the meltwater stream. Third, in contrast to ice core melter systems in which the meltwater is directly channeled to online instruments for continuous …

Collaborative Research: Integrated Geophysical And Hydrogeologic Study Of A Large Maine Peatland, Andrew S. Reeve

University of Maine Office of Research Administration: Grant Reports

Solute transport controls vegetation and water chemistry gradients in peatlands. Dispersive mixing and advective transport in peat will be measured in laboratory column experiments and in a natural gradient tracer test in a peatland to determine the relative importance of these processes. We will assess the retardation of solutes by matrix diffusion and the applicability of a dual-domain model. Electrical geophysical methods, verified through direct measurements, will be used to track tracer migration.

An extensive geophysical and hydrogeologic characterization of the peatland will map variability in peat depth across the basin and identify stratigraphy. Ground-penetrating radar and resistivity/induced polarization imaging …

Implications Of Spatial Autocorrelation And Dispersal For The Modeling Of Species Distributions, Volker Bahn

Electronic Theses and Dissertations

Modeling the geographical distributions of wildlife species is important for ecology and conservation biology. Spatial autocorrelation in species distributions poses a problem for distribution modeling because it invalidates the assumption of independence among sample locations. I explored the prevalence and causes of spatial autocorrelation in data from the Breeding Bird Survey, covering the conterminous United States, using Regression Trees, Conditional Autoregressive Regressions (CAR), and the partitioning of variance. I also constructed a simulation model to investigate dispersal as a process contributing to spatial autocorrelation, and attempted to verify the connection between dispersal and spatial autocorrelation in species' distributions in empirical …

Glacial History Of The Amundsen Sea Shelf, Thomas B. Kellogg, Daniel Belknap, Davida Kellogg, Terence Hughes

University of Maine Office of Research Administration: Grant Reports

This award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, supports a marine geological investigation of the Amundsen Sea region toward a better understanding of the deglaciation history of the West Antarctic Ice Sheet (WAIS). The WAIS may be inherently unstable because it is the last marine-based ice sheet in the world. Unlike other embayments in West Antarctica, major ice streams draining into the Amundsen Sea from the interior of the WAIS lack buttressing ice shelves. Mass balance data for the distal portions of these ice streams (Pine Island and Thwaites glaciers) appear to …

Barry Saltzman And The Theory Of Climate, Kirk A. Maasch, R. J. Oglesby, A. Fournier

Earth Science Faculty Scholarship

Barry Saltzman was a giant in the fields of meteorology and climate science. A leading figure in the study of weather and climate for over 40 yr, he has frequently been referred to as the "father of modern climate theory." Ahead of his time in many ways, Saltzman made significant contributions to our understanding of the general circulation and spectral energetics budget of the atmosphere, as well as climate change across a wide spectrum of time scales. In his endeavor to develop a unified theory of how the climate system works, lie played a role in the development of energy …

Climatic And Lithogenic Controls On Soil Organic Matter-Mineral Associations, Rota Wagai

Electronic Theses and Dissertations

Interactions of organic matter (OM) with soil mineral phases strongly affect the storage and dynamics of soil OM as well as other ecosystem processes. This study examined aspects of organo-mineral associations in soils at different scales. First, I assessed the potential controls of climate and parent rock type on organo-mineral associations using two sets of undisturbed tropical forest soils developed on two contrasting rocks along an altitudinal gradient in Borneo, Southeast Asia. Density fractionations showed that OM stored in surface mineral soils partitioned towards plant detritus fraction under cooler climates on both rock types. Thus climate exerted stronger control on …

Hierarchies For Event-Based Modeling Of Geographic Phenomena, Rui Zhang

Electronic Theses and Dissertations

Modeling the dynamic aspect, or change, of geographic phenomena is essential to explain the evolution of geographic entities and predict their future. Event-based modelling, describing the occurrences rather than states of geographic phenomena, gives an explicit treatment of such change, but currently does not have the support of the mechanisms to enable the shifts among different granularities of events. To account for different tasks, a hierarchical representation of the event space at different granularities is needed.

This thesis presents an event-based model; a general framework for representing events based on precondition and postcondition using Allen's temporal interval logic. It captures …

Spatial Variability In Biogenic Gas Accumulations In Peat Soils Is Revealed By Ground Penetrating Radar (Gpr), Xavier Comas, Lee Slater, Andrew S. Reeve

Earth Science Faculty Scholarship

We performed surface and borehole ground penetrating radar (GPR) tests, together with moisture probe measurements and direct gas sampling to detect areas of biogenic gas accumulation in a northern peatland. The main findings are: (1) shadow zones (signal scattering) observed in surface GPR correlate with areas of elevated CH4 and CO2 concentration; (2) high velocities in zero offset profiles and lower water content inferred from moisture probes correlate with surface GPR shadow zones; (3) zero offset profiles depict depth variable gas accumulation from 0-10% by volume; (4) strong reflectors may represent confining layers restricting upward gas migration. Our results have …

Improving Performance Characteristics Of Hyphenated Preconcentrator Gc Fourier Transform Ion Cyclotron Resonance Mass Spectrometry: A "Gold Standard" For Sensor Development, Touradj Solouski

University of Maine Office of Research Administration: Grant Reports

Professor Touradj Solouki of the University of Maine at Orono is supported by the Analytical and Surface Chemistry Program to investigate cryofocusing of analytes in an Electrospray Ionization Fourier Transform Ion Cyclotron Resonance (ESI-FT-ICR) mass spectrometer. To overcome sensitivity problems of FT-ICR, Professor Solouki has added a pre-concentration (PC) gas chromatograph (GC) step to his setup. The goal of this Small Grant for Exploratory Research is to add an additional device: a cryofocuser after the GC. This is predicted to improve the detection limit by two orders of magnitude, and mass resolving power by a factor of 5-10. The PI …

Reply To Comment By Doran Et Al. On "El Nino Suppresses Antarctic Warming", Nancy A.N. Bertler, Peter J. Barrett, Paul Andrew Mayewski, Ryan L. Fogt, Karl J. Kreutz, James Shulmeister

Earth Science Faculty Scholarship

No abstract provided.

Expansion And Renovation Of The Darling Marine Center Library, Kevin Eckelbarger

University of Maine Office of Research Administration: Grant Reports

This award provides partial funding for expansion and modernization of the library at The Darling Marine Center. The library currently contains more marine-related holdings than any other library in Maine, and is an important resource for researchers and students interested in the biology of the Gulf of Maine and the Maine coast. Because of current space limitations, a third of the library's holdings are stored in other buildings and attic spaces. The library is not wheelchair accessible, has no significant study space, and provides only limited access to electronic databases. The proposed changes include: 1) construction of a 1,500 sq. …

U.S.-Russia Cooperative Research: Designing Gold(I) Complexes For New Materials, Alice E. Bruce, Mitchell Bruce, Dmitri Lemenosvsii, Victor Dyadchenko,

University of Maine Office of Research Administration: Grant Reports

This award in International Programs and the Inorganic, Bioinorganic, and Organometallic Chemistry Program supports collaborative research by Dr. Alice E. Bruce of the University of Maine and Dr. Dmitri Lemenovskii of Moscow State University (Russia). The goal of the project is to design gold complexes that will be useful in new materials, such as liquid crystals. Organogold compounds containing rod-shaped molecules will be synthesized and structurally characterized. Lattice effects in liquid and solid phases formed from the compounds will be studied. Both groups are experienced in the synthetic aspects of the research, but will take advantage of the University of …

Collaborative Research: Coupled Atmosphere-Ocean Model Study Of Wintertime Air-Sea Interaction Off The East Coast Of North America, Huijie Xue

University of Maine Office of Research Administration: Grant Reports

In this project, the PIs will continue their investigation of wintertime air-sea interaction processes off the east coast of North America, emphasizing the Gulf Stream (GS) region east of Cape Hatteras and the coastal region in the Middle Atlantic Bight (MAB). Analyses of model results will include temporal and spatial variation of the air-sea exchanges of heat, moisture and momentum, evolution of the oceanic mixed layer and the marine atmospheric boundary layer during storm passage, and momentum, heat and potential vorticity balances in the ocean

Controls On The Basal Water Pressure In Subglacial Channels Near The Margin Of The Greenland Ice Sheet, Andreas P. Ahlstrøm, Johan J. Mohr, Niels Reeh, Erik Lintz Christensen, Roger Hooke

Earth Science Faculty Scholarship

Assuming a channelized drainage system in steady state, we investigate the influence of enhanced surface melting on the water pressure in subglacial channels, compared to that of changes in conduit geometry, ice rheology and catchment variations. The analysis is carried out for a specific part of the western Greenland ice-sheet margin between 66 degrees N and 66 degrees 30' N using new high-resolution digital elevation models of the subglacial topography and the ice-sheet surface, based on an airborne ice-penetrating radar survey in 2003 and satellite repeat-track interferometric synthetic aperture radar analysis of European Remote-sensing Satellite 1 and 2 (ERS-1/-2) imagery, …

Increasing Silicon Concentrations In Bohemian Forest Lakes, J. Veselý, V. Majer, J. Kopácek, J. Safanda, Stephen A. Norton

Earth Science Faculty Scholarship

Long-term trends of dissolved silicon (Si) concentrations in five glacial lakes in the Bohemian Forest, Czech Republic, recovering from acidification show higher mobility of Si from the soil to surface waters despite lower atmospheric deposition of acids. Si increased by 0.95 to 1.95 mu mol yr(-1) (36 to 51%) from 1986-2004 and with increasing pH. A change in soil solution conditions because of a sharp decrease in acidic deposition has led to marked decline in Al mobility and to considerable decreases in dissolved Al, especially Al3+. The increase in Si may be related to: (1) unblocking of the inhibitory effect …

Lgm Summer Climate On The Southern Margin Of The Laurentide Ice Sheet: Wet Or Dry?, David H. Bromwich, E. Richard Toracinta, Robert J. Oglesby, James L. Fastook, Terence J. Hughes

Earth Science Faculty Scholarship

Regional climate simulations are conducted using the Polar fifth-generation Pennsylvania State University (PSU)-NCAR Mesoscale Model (MM5) with a 60-km horizontal resolution domain over North America to explore the summer climate of the Last Glacial Maximum (LGM: 21 000 calendar years ago), when much of the continent was covered by the Laurentide Ice Sheet (LIS). Output from a tailored NCAR Community Climate Model version 3 (CCM3) simulation of the LGM climate is used to provide the initial and lateral boundary conditions for Polar MM5. LGM boundary conditions include continental ice sheets, appropriate orbital forcing, reduced CO2 concentration, paleovegetation, modified sea surface …

Stratigraphic Variation Within Polar Firn Caused By Differential Accumulation And Ice Flow: Interpretation Of A 400 Mhz Short-Pulse Radar Profile From West Antarctica, Steven A. Arcone, Vandy Blue Spikes, Gordon S. Hamilton

Earth Science Faculty Scholarship

We investigate causes of the stratigraphic variation revealed in a 177 km, 400 MHz short-pulse radar profile of firn from West Antarctica. The profile covers 56 m depth, and its direction was close to those of the ice flow and mean wind. The average, near-surface accumulation rates calculated from the time delays of one radar horizon consistently show minima on leeward slopes and maxima on windward slopes, confirming an earlier study based on stake observations. The stratigraphic variation includes up to 30 m depth variation in individual horizons over tens of km, fold limbs that become progressively steeper with depth, …

Stable-Isotope Time Series And Precipitation Origin From Firn-Core And Snow Samples, Altai Glaciers, Siberia, Vladimir B. Aizen, Elena M. Aizen, Koji Fujita, Stanislav A. Nikitin, Karl J. Kreutz, L. Nozomu Takeuchi

Earth Science Faculty Scholarship

In the summers of 2001 and 2002, glacio-climatological research was performed at 4110-4120 m a.s.l. on the Belukha snow/firn plateau, Siberian Altai. Hundreds of samples from snow pits and a 21 m snow/firn core were collected to establish the annual/seasonal/monthly depth-accumulation scale, based on stable-isotope records, stratigraphic analyses and meteorological and synoptic data. The fluctuations of water stable-isotope records show well-preserved seasonal variations. The delta(18)O and delta D relationships in precipitation, snow pits and the snow/firn core have the same slope to the covariance as that of the global meteoric water line. The origins of precipitation nourishing the Belukha plateau …

A New Velocity Map For Byrd Glacier, East Antarctica, From Sequential Aster Satellite Imagery, Leigh Stearns, Gordon Hamilton

Earth Science Faculty Scholarship

New ice-velocity measurements are obtained for the main trunk of Byrd Glacier, East Antarctica, using recently acquired Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) imagery. The velocities are derived from the application of a cross-correlation technique to sequential images acquired in 2000 and 2001. Images were co-registered and ortho-rectified with the aid of a digital elevation model (DEM) generated from ASTER stereo imagery. This paper outlines the process of DEM generation, image co-registration and correction, and the application of the cross-correlation technique to obtain ice velocities. Comparison of the new velocity map with earlier measurements of velocity from 1978 …