Multivariate Spectral Analysis Of Crism Data To Characterize The Composition Of Mawrth Vallis, 2018 Wesleyan University
Multivariate Spectral Analysis Of Crism Data To Characterize The Composition Of Mawrth Vallis, Melissa Luna
No abstract provided.
Identifying Riparian Zones Best Suited To Installation Of Saturated Buffers: A Preliminary Multi-Watershed Assessment, 2018 United States Department of Agriculture
Identifying Riparian Zones Best Suited To Installation Of Saturated Buffers: A Preliminary Multi-Watershed Assessment, M. D. Tomer, D. B. Jaynes, S. A. Porter, D. E. James, T. M. Isenhart
Thomas M. Isenhart
Saturated riparian buffers are a new type of conservation practice that divert subsurface tile drainage water from direct discharge to surface water into distribution pipes that discharge the tile water into riparian soils. This enables natural processes of biological uptake and denitrification to decrease nutrient loads that are being lost from croplands via tile drains, reducing water quality impacts from agriculture at relatively little cost. This chapter suggests and evaluates draft criteria that identify riparian zones within a watershed that are suited to installation of saturated buffers. Soils criteria, evaluated using soil survey information, include subsurface accumulations of soil organic ...
Nitrous Oxide Emissions From Riparian Forest Buffers, Warm-Season And Cool-Season Grass Filters, And Crop Fields, 2018 Iowa State University
Nitrous Oxide Emissions From Riparian Forest Buffers, Warm-Season And Cool-Season Grass Filters, And Crop Fields, D. G. Kim, Thomas M. Isenhart, Timothy B. Parkin, Richard C. Schultz, Thomas E. Loynachan, James W. Raich
Thomas M. Isenhart
Denitrification within riparian buffers may trade reduced nonpoint source pollution of surface waters for increased greenhouse gas emissions resulting from denitrification-produced nitrous oxide (N2O). However, little is known about the N2O emission within conservation buffers established for water quality improvement or of the importance of short-term N2O peak emission following rewetting dry soils and thawing frozen soils. Such estimates are important in reducing uncertainties in current Intergovernmental Panel on Climate Change (IPCC) methodologies estimating soil N2O emission which are based on N inputs. This study contrasts N2O emission from riparian buffer systems of three perennial vegetation types and an adjacent ...
Phosphorus Source--Sink Relationships Of Stream Sediments In The Rathbun Lake Watershed In Southern Iowa, Usa, 2018 Iowa State University
Phosphorus Source--Sink Relationships Of Stream Sediments In The Rathbun Lake Watershed In Southern Iowa, Usa, Najphak Hongthanat, John L. Kovar, Michael L. Thompson, James R. Russell, Thomas M. Isenhart
Thomas M. Isenhart
The surface waters of Rathbun Lake watershed in southern Iowa are impacted by agricultural sources of sediments and nutrients, including phosphorus (P). Because stream sediments often play an important role in regulating P concentrations in stream water, we investigated sediment-water column P relationships in four creeks within the watershed and then evaluated the relationship between sediment properties and indicators of the risk of P loss. Based on Mehlich-3-extractable P (17 to 68 mg kg -1) and degree of P saturation (2 to 12 %), stream bank and bed sediments at the four sites were unlikely to serve as major sources of ...
A Survey To Better Understand The Use Of The Terms “Colluvium” And “Alluvium”, 2018 Iowa State University
A Survey To Better Understand The Use Of The Terms “Colluvium” And “Alluvium”, Bradley A. Miller, Jérôme Juilleret
Bradley A. Miller
We need your help to fully understand how scientists from different backgrounds define the terms “colluvium” and “alluvium.” We ask that you contribute your perspective by taking the survey at http://goo.gl/forms/fV8RBWKjis. The closing deadline is October 31, 2016. The feedback so far has been positive, and many participants have described the experience as fun. Many commented on how the survey challenged their thinking about these sediments, causing them to more carefully consider potential gaps in their definitions for the terms and their strategies for identifying the materials. Others have expressed great interest in the results because ...
An Optical Method For Carbon Dioxide Isotopes And Mole Fractions In Small Gas Samples: Tracing Microbial Respiration From Soil, Litter, And Lignin, Steven J. Hall, Wenjuan Huang, Kenneth E. Hammel
Steven J. Hall
Carbon dioxide isotope (δ13C value) measurements enable quantification of the sources of soil microbial respiration, thus informing ecosystem C dynamics. Tunable diode lasers (TDLs) can precisely measure CO2 isotopes at low cost and high throughput, but are seldom used for small samples (≤5 mL). We developed a TDL method for CO2 mole fraction ([CO2]) and δ13C analysis of soil microcosms.
Peaks in infrared absorbance following constant volume sample injection to a carrier were used to independently measure [12CO2] and [13CO2] for subsequent calculation of δ13C values. Using parallel soil incubations receiving differing C substrates, we partitioned respiration from ...
Elevated Moisture Stimulates Carbon Loss From Mineral Soils By Releasing Protected Organic Matter, 2018 Iowa State University
Elevated Moisture Stimulates Carbon Loss From Mineral Soils By Releasing Protected Organic Matter, Wenjuan Huang, Steven J. Hall
Steven J. Hall
Moisture response functions for soil microbial carbon (C) mineralization remain a critical uncertainty for predicting ecosystem-climate feedbacks. Theory and models posit that C mineralization declines under elevated moisture and associated anaerobic conditions, leading to soil C accumulation. Yet, iron (Fe) reduction potentially releases protected C, providing an under-appreciated mechanism for C destabilization under elevated moisture. Here we incubate Mollisols from ecosystems under C3/C4 plant rotations at moisture levels at and above field capacity over 5 months. Increased moisture and anaerobiosis initially suppress soil C mineralization, consistent with theory. However, after 25 days, elevated moisture stimulates cumulative gaseous C-loss as ...
Selected Highlights In American Soil Science History From The 1980s To The Mid-2010s, 2018 Dickinson State University
Selected Highlights In American Soil Science History From The 1980s To The Mid-2010s, Eric C. Brevik, Jeffrey A. Homburg, Bradley A. Miller, Thomas E. Fenton, James A. Doolittle, Samuel J. Indorante
Bradley A. Miller
The beginning of the 20th century through the 1970s were good times for soil science in the USA, with relatively strong funding and overall growth in the profession. However, the soil science discipline in the USA hit hard times in the 1980s and 1990s. Federal funding for soil survey work began to decline as did student numbers in university programs and membership in the Soil Science Society of America (SSSA). Despite this, there were still many positive advances within soil science in the USA during these two decades. There was an increased use of geophysical instrumentation, remote sensing, geographic information ...
Scale-Dependent Linkages Between Nitrate Isotopes And Denitrification In Surface Soils: Implications For Isotope Measurements And Models, Steven J. Hall, Samantha R. Weintraub, David Bowling
Steven J. Hall
Natural abundance nitrate (NO3−) isotopes represent a powerful tool for assessing denitrification, yet the scale and context dependence of relationships between isotopes and denitrification have received little attention, especially in surface soils. We measured the NO3−isotope compositions in soil extractions and lysimeter water from a semi-arid meadow and lawn during snowmelt, along with the denitrification potential, bulk O2, and a proxy for anaerobic microsites. Denitrification potential varied by three orders of magnitude and the slope of δ18O/δ15N in soil-extracted NO3− from all samples measured 1.04 ± 0.12 (R2 = 0.64, p < 0.0001), consistent with fractionation from denitrification. However, δ15N of extracted NO3− was often lower than bulk soil δ15N (by up to 24 ‰), indicative of fractionation during nitrification that was partially overprinted by denitrification. Mean NO3− isotopes in lysimeter water differed from soil extractions by up to 19 ‰ in δ18O and 12 ‰ in δ15N, indicating distinct biogeochemical processing in relatively mobile water versus soil microsites. This implies that NO3− isotopes in streams, which are predominantly fed by mobile water, do not fully reflect terrestrial soil N cycling. Relationships between potential denitrification and δ15N of extracted NO3− showed a strong threshold effect culminating in a null relationship at high denitrification rates. Our observations of (1) competing fractionation from nitrification and denitrification in redox-heterogeneous surface soils, (2) large NO3− isotopic differences between relatively immobile and mobile water pools, (3) and the spatial dependence of δ18O/δ15N relationships suggest caution in using NO3− isotopes to infer site or watershed-scale patterns in denitrification.
Drivers And Patterns Of Iron Redox Cycling From Surface To Bedrock In A Deep Tropical Forest 1 Soil: A New Conceptual Model, Steven J. Hall, Daniel Liptzin, Heather L. Buss, Kristen Deangelis, Whendee L. Silver
Steven J. Hall
Iron (Fe) reduction and oxidation are important biogeochemical processes coupled to decomposition, nutrient cycling, and mineral weathering, but factors controlling their rates and spatial distribution with depth are poorly understood in terrestrial soils. In aquatic ecosystems, Fe reduction often occurs below a zone of oxic sediments. We tested an alternative conceptual model for Fe redox cycling in terrestrial soils using a deep humid tropical forest soil profile. We hypothesized that Fe reduction in anaerobic microsites scales with depth variation in labile C and Fe availability, as opposed to bulk oxygen (O2). We measured bulk O2 at multiple depths from 0 ...
Discovery And Geology Of The Guinness World Record Lake Copper, Lake Superior, Michigan, 2018 Michigan Technological University
Discovery And Geology Of The Guinness World Record Lake Copper, Lake Superior, Michigan, Theodore J. Bornhorst, Robert Barron
Theodore J. Bornhorst
No abstract provided.
Genuine Faculty-Mentored Research Experiences For In-Service Science Teachers: Increases In Science Knowledge, Perception, And Confidence Levels, 2018 University of Nebraska at Omaha
Genuine Faculty-Mentored Research Experiences For In-Service Science Teachers: Increases In Science Knowledge, Perception, And Confidence Levels, Christine E. Cutucache, Heather D. Leas, Neal F. Grandgenett, Kari L. Nelson, Steven N. Rodie, Robert Duncan Shuster, Chris Schaben, William E. Tapprich
Biology Faculty Publications
The overall purpose of this multifocused study was to explore how participation in genuine mentored scientific research experiences impacts in-service science teachers and the knowledge and skills needed for their own science teaching. The research experiences resulted from a partnership between the University of Nebraska at Omaha and the Omaha Public School District. This Teacher- Researcher Partnership Program facilitated opportunities in inquiry, science content, interaction with laboratory instrumentation and technologies, critical discussion of literature, and dissemination of findings for participating in-service science teacher professional development utilizing an inquiry-based theoretical framework wherein we examined science teacher preparation via inquiry-based methods in ...
Quantitative Map Literacy: A Cross Between Map Literacy And Quantitative Literacy, 2018 University of South Florida
Quantitative Map Literacy: A Cross Between Map Literacy And Quantitative Literacy, Ming Xie, H. L. Vacher, Steven Reader, Elizabeth Walton
We define quantitative map literacy (QML), a cross between map literacy and quantitative literacy (QL), as the concepts and skills required to accurately read, use, interpret, and understand the quantitative information embedded in a geospatial representation of data on a geographic background. Long used as tools in technical geographic fields, maps are now a common vehicle for communicating quantitative information to the public. As such, QML has potential to stand alongside health numeracy and financial literacy as an identifiable subdomain of transdisciplinary QL.
What concepts and skills are crucial for QML? The obvious answer is, “It depends on the type ...
Quantifying The Level Of Inquiry In A Reformed Introductory Geology Lab Course, 2017 Iowa State University
Quantifying The Level Of Inquiry In A Reformed Introductory Geology Lab Course, Elizabeth Moss, Cinzia Cervato
As part of a campus-wide effort to transform introductory science courses to be more engaging and more accurately convey the excitement of discovery in science, the curriculum of an introductory physical geology lab course was redesigned. What had been a series of “cookbook” lab activities was transformed into a sequence of activities based on scientific inquiry and cooperative learning. The first two semesters were spent developing and implementing the new lab activities, and two more semesters were spent refining them. In the second semester of each of these two phases, students enrolled in the lab completed a 15-question version of ...
Wrf Summer Extreme Daily Precipitation Over The Cordex Arctic, 2017 email@example.com
Wrf Summer Extreme Daily Precipitation Over The Cordex Arctic, Justin M. Glisan, William J. Gutowski Jr.
William J. Gutowski, Jr.
We analyze daily precipitation extremes produced by a six-member ensemble of the Pan-Arctic Weather Research and Forecasting (WRF) that simulated 19 years on the Coordinated Regional Climate Downscaling Experiment (CORDEX) Arctic domain for the Arctic summer. Attention focuses on four North American analysis regions defined using climatological records, regional weather patterns, and geographical/topographical features. We compare simulated extremes with those occurring at corresponding observing stations in the U.S. National Climate Data Center's Global Summary of the Day. Our analysis focuses on variations in features of the extremes such as magnitudes, spatial scales, and temporal regimes between regions ...
Water Vapor Layers In Storm-Fest Rawinsonde Observations, 2017 Iowa State University
Water Vapor Layers In Storm-Fest Rawinsonde Observations, John P. Iselin, William J. Gutowski Jr.
William J. Gutowski, Jr.
The STORM-FEST (Fronts Experiment Systems Test) rawinsonde data were analyzed to determine the abundance and characteristics of moist layers within the troposphere. A moist layer was defined as a local maximum in relative humidity with lower relative humidity air above and below. Moist layers under the criteria occur in over half the soundings with an average location between 600 and 500 mb and an average thickness of approximately 120 mb. The layers also appeared to be more nearly aligned with isentropic, rather than isobaric, surfaces. Compositing of relative humidity profiles with a layer at approximately the same level showed an ...
Atmospheric Water Vapor Transport In Ncep–Ncar Reanalyses: Comparison With River Discharge In The Central United States, William J. Gutowski Jr., Yibin Chen, Zekai Ötles
William J. Gutowski, Jr.
The authors extract the water transport produced by the National Centers for Environmental Prediction reanalysis for a 10-yr period, 1984–93, and compare its convergence into two river basins with an independent dataset, river discharge (streamflow). Analysis focuses on two basins in the United States, the Upper Mississippi and the Ohio–Tennessee Basins, where the relatively high density of routine upper-air observations might be expected to give the reanalysis its closest rendition of the actual water transport. Over periods of several years, water input by the atmosphere should match water output from these basins in streamflow. However, in both basins ...
Iron Isotope Fractionation During Fe(Ii) Oxidation Mediated By The Oxygen-Producing Marine Cyanobacterium Synechococcus Pcc 7002, Elizabeth S. Swanner, Timm Bayer, Wenfang Wu, Likai Hao, Martin Obst, Anneli Sundman, James Martin Byrne, F. M. Michel, I. C. Kleinhanns, A. Klapper, R. Schoenberg
Elizabeth D. Swanner
In this study, we couple iron isotope analysis to microscopic and mineralogical investigation of iron speciation during circumneutral Fe(II) oxidation and Fe(III) precipitation with photosynthetically produced oxygen. In the presence of the cyanobacterium Synechococcus PCC 7002, aqueous Fe(II) (Fe(II)aq) is oxidized and precipitated as amorphous Fe(III) oxyhydroxide minerals (iron precipitates, Feppt), with distinct isotopic fractionation (ε56Fe) values determined from fitting the δ56Fe(II)aq (1.79‰ and 2.15‰) and the δ56Feppt (2.44‰ and 2.98‰) data trends from two replicate experiments. Additional Fe(II) and Fe(III) phases were detected using microscopy ...
Perceived Risk Of Predation Affects Reproductive Life - History Traits In Gambusia Holbrooki, But Not In Heterandria Formosa, 2017 Department of Biological Sciences Florida International University, and School of Life Sciences, University of KwaZulu-Nata
Perceived Risk Of Predation Affects Reproductive Life - History Traits In Gambusia Holbrooki, But Not In Heterandria Formosa, Shomen Mukherjee, Michael R. Heithaus, Joel C. Trexler, Jayanti Ray-Mukherjee, Jeremy Vaudo
Key to predicting impacts of predation is understanding the mechanisms through which predators impact prey populations. While consumptive effects are well-known, non-consumptive predator effects (risk effects) are increasingly being recognized as important. Studies of risk effects, however, have focused largely on how trade-offs between food and safety affect fitness. Less documented, and appreciated, is the potential for predator presence to directly suppress prey reproduction and affect life-history characteristics. For the first time, we tested the effects of visual predator cues on reproduction of two prey species with different reproductive modes, lecithotrophy (i.e. embryonic development primarily fueled by yolk) and ...
Mitigating Non-Linearity In Full Waveform Inversion Using Scaled-Sobolev Norms, 2017 The University of Western Ontario
Mitigating Non-Linearity In Full Waveform Inversion Using Scaled-Sobolev Norms, Mohammad Akbar Hosain Zuberi
Electronic Thesis and Dissertation Repository
Seismic full waveform inversion (FWI) is a non-linear problem. The Born approximation provides a way to linearize FWI and obtain a gradient in a computationally efficient manner. However, this linearization is only valid if the background velocity is sufficiently known, which often is not possible in practice. There have been various attempts at solving problems associated with the non-linearity of FWI by separating the problems of background and scatterer inversion. Most of the methods, however either depend on the availability of low frequencies and large offsets in the data, or separate the spatial scales completely, which removes the scattered information ...