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Articles 1 - 13 of 13
Full-Text Articles in Biogeochemistry
Temperature And Hydrologic Context Influence Methane Variability In A Low-Salinity Marsh, Zoie Brauser
Temperature And Hydrologic Context Influence Methane Variability In A Low-Salinity Marsh, Zoie Brauser
Dissertations and Theses
Coastal wetlands are biogeochemical hotspots that capture and transform carbon and nutrients. Wetland restoration is increasingly used as a climate mitigation strategy because of wetlands' capacity to sequester large amounts of carbon. However, low-salinity tidal marshes exhibit high variability in methane (CH4) emissions, which could partially offset carbon sequestration under certain conditions. Understanding the drivers of CH4 variability is crucial for restoration and conservation work. This project uses an observational research approach to assess the relationships between environmental factors and carbon dioxide (CO2) and CH4 soil gas fluxes in a restored low-salinity tidal marsh …
Remediating History: A Review Of Restoration For Creeks Polluted From Historical Mining Sites, With The Red Boy Mine As A Primary Case Study, Kara Atiyeh
University Honors Theses
I conducted a literature review to examine the key aspects of restoring watersheds affected by pollution from historical mining. This review is then applied to a case study discussion of the Red Boy Mine and Clear Creek remediation project in Granite, Oregon. The goal of this discussion is to explore how an analysis of site conditions along with current literature on management practices can help guide these projects. Thousands of abandoned hard rock mines remain throughout the country, and many pose serious environmental health effects. Heavy metals like cadmium, nickel, and copper are brought to the surface from mining activity, …
The Discovery Of Diverse Picophytoplankton Populations In The Columbia And Willamette Rivers Using Flow Cytometry, Kylee M. Lamberson
The Discovery Of Diverse Picophytoplankton Populations In The Columbia And Willamette Rivers Using Flow Cytometry, Kylee M. Lamberson
Chemistry Undergraduate Departmental Honors Theses
As important primary producers, picophytoplankton determine the flow of carbon and energy in aquatic ecosystems. Picocyanobacteria are one picophytoplankton group known to be dominant in oceans and lakes, but they are still poorly understood in river systems. This project examined picophytoplankton communities in two distinct river systems: the Columbia and Willamette Rivers in Portland, Oregon. I aimed to characterize and quantify the picophytoplankton populations in the context of the environmental conditions of the two rivers. I used flow cytometry to detect cells based on their relative size and pigment fluorescence. I sampled nearly weekly for ten months to capture population …
Inverse Modeling Of Atmospheric Ch4 And Δ13C-Ch4 Measurements From Surface Observation Sites To Understand Trends In Global Methane Emissions Over More Than Three Decades, Sayantani Karmakar
Inverse Modeling Of Atmospheric Ch4 And Δ13C-Ch4 Measurements From Surface Observation Sites To Understand Trends In Global Methane Emissions Over More Than Three Decades, Sayantani Karmakar
Dissertations and Theses
Methane (CH4) is the second most important greenhouse gas with a radiative forcing of 0.97 W/m2 including both direct and indirect effects and a global warming potential of 28 over a 100-year time horizon. Unlike CO2 whose rate of growth in the atmosphere has remained positive and increased in recent decades, the behavior of atmospheric methane is considerably more complex and is much less understood on account of the spatiotemporal variability of its emissions which include biogenic (e.g., wetlands, ruminants, rice agriculture), thermogenic (fossil fuels), and pyrogenic (i.e., biomass burning) sources. After sustained growth during most …
Scenes From The Swale: Investigating Spatial And Temporal Dimensions Of Nitrogen Cycling In Urban Stormwater Bioretention Facilities, Erin Nicole Looper
Scenes From The Swale: Investigating Spatial And Temporal Dimensions Of Nitrogen Cycling In Urban Stormwater Bioretention Facilities, Erin Nicole Looper
Dissertations and Theses
Urban development is transforming landscapes at unprecedented rates. Human activities and landscape modifications associated with urbanization extensively increase hydrologic demands and modify natural hydrologic systems; consequently, population growth occurring in urban areas increases pressure on water resources. Urban aquatic ecosystems are vulnerable to impacts associated with increased connectivity with urban surfaces and hydrologic changes that initiate long-term changes in receiving waterbodies. Nitrogen (N) loading from urban and suburban catchments to receiving surface waters can lead to impairment of aquatic ecosystems and is a concern in many cities with water quality issues. To improve urban water quality, cities are increasingly adopting …
Searching For Biogeochemical Hot Spots In Three Dimensions: Soil C And N Cycling In Hydropedologic Settings In A Northern Hardwood Forest, Jennifer L. Morse, S F. Werner, Cody P. Gillin, Christine L. Goodale, Scott W. Bailey, Kevin J. Mcguire, Peter M. Groffman
Searching For Biogeochemical Hot Spots In Three Dimensions: Soil C And N Cycling In Hydropedologic Settings In A Northern Hardwood Forest, Jennifer L. Morse, S F. Werner, Cody P. Gillin, Christine L. Goodale, Scott W. Bailey, Kevin J. Mcguire, Peter M. Groffman
Environmental Science and Management Faculty Publications and Presentations
Understanding and predicting the extent, location, and function of biogeochemical hot spots at the watershed scale is a frontier in environmental science. We applied a hydropedologic approach to identify (1) biogeochemical differences among morphologically distinct hydropedologic settings and (2) hot spots of microbial carbon (C) and nitrogen (N) cycling activity in a northern hardwood forest in Hubbard Brook Experimental Forest, New Hampshire, USA. We assessed variables related to C and N cycling in spodic hydropedologic settings (typical podzols, bimodal podzols, and Bh podzols) and groundwater seeps during August 2010. We found that soil horizons (Oi/Oe, Oa/A, and B) differed significantly …
Microbial Biogeochemistry Of Boiling Springs Lake: A Physically Dynamic, Oligotrophic, Low-P H Geothermal Ecosystem, Patricia Lynne Siering, Gordon V. Wolfe, Mark S. Wilson, A. N. Yip, Cynthia M. Carey, Colin D. Wardman, Russell Scott Shapiro, Kenneth M. Stedman, Jennifer E. Kyle, Tong Yuan, Joy D. Van Nostrand, Zhili He, Jizhong Zhou
Microbial Biogeochemistry Of Boiling Springs Lake: A Physically Dynamic, Oligotrophic, Low-P H Geothermal Ecosystem, Patricia Lynne Siering, Gordon V. Wolfe, Mark S. Wilson, A. N. Yip, Cynthia M. Carey, Colin D. Wardman, Russell Scott Shapiro, Kenneth M. Stedman, Jennifer E. Kyle, Tong Yuan, Joy D. Van Nostrand, Zhili He, Jizhong Zhou
Biology Faculty Publications and Presentations
Boiling Springs Lake (BSL) in Lassen Volcanic National Park, California, is North America's largest hot spring, but little is known about the physical, chemical, and biological features of the system. Using a remotely operated vessel, we characterized the bathymetry and near-surface temperatures at sub-meter resolution. The majority of the 1.2 ha, pH 2.2 lake is 10 m deep and 50-52 [degrees]C, but temperatures reach 93 [degrees]C locally. We extracted DNA from water and sediments collected from warm (52 [degrees]C) and hot (73-83 [degrees]C) sites separated by 180 m. Gene clone libraries and functional gene microarray (GeoChip 3.0) were used to …
An Individual-Based Process Model To Simulate Landscape-Scale Forest Ecosystem Dynamics, Rupert Seidi, Werner Rammer, Robert M. Scheller, Thomas A. Spies
An Individual-Based Process Model To Simulate Landscape-Scale Forest Ecosystem Dynamics, Rupert Seidi, Werner Rammer, Robert M. Scheller, Thomas A. Spies
Environmental Science and Management Faculty Publications and Presentations
Forest ecosystem dynamics emerges from nonlinear interactions between adaptive biotic agents (i.e., individual trees) and their relationship with a spatially and temporally heterogeneous abiotic environment. Understanding and predicting the dynamics resulting from these complex interactions is crucial for the sustainable stewardship of ecosystems, particularly in the context of rapidly changing environmental conditions. Here we present iLand (the individual-based forest landscape and disturbance model), a novel approach to simulating forest dynamics as an emergent property of environmental drivers, ecosystem processes and dynamic interactions across scales. Our specific objectives were (i) to describe the model, in particular its novel approach to simulate …
Phosphorus Export From A Restored Wetland Ecosystem In Response To Natural And Experimental Hydrologic Fluctuations, Marcelo Ardón, Shaena Montanari, Jennifer L. Morse, Martin W. Doyle, Emily S. Bernhardt
Phosphorus Export From A Restored Wetland Ecosystem In Response To Natural And Experimental Hydrologic Fluctuations, Marcelo Ardón, Shaena Montanari, Jennifer L. Morse, Martin W. Doyle, Emily S. Bernhardt
Environmental Science and Management Faculty Publications and Presentations
Wetland restoration is a commonly used approach to reduce nutrient loading to freshwater and coastal ecosystems, with many wetland restoration efforts occurring in former agricultural fields. Restored wetlands are expected to be effective at retaining or removing both nitrogen and phosphorus (P), yet restoring wetland hydrology to former agricultural fields can lead to the release of legacy fertilizer P. Here, we examined P cycling and export following rewetting of the Timberlake Restoration Project, a 440 ha restored riverine wetland complex in the coastal plain of North Carolina. We also compared P cycling within the restored wetland to two minimally disturbed …
Virus Silicification Under Simulated Hot Spring Conditions, James R. Laidler, Kenneth M. Stedman
Virus Silicification Under Simulated Hot Spring Conditions, James R. Laidler, Kenneth M. Stedman
Biology Faculty Publications and Presentations
Silicification of organisms in silica-depositing environments can impact both their ecology and their presence in the fossil record. Although microbes have been silicified under laboratory and environmental conditions, viruses have not. Bacteriophage T4 was successfully silicified under laboratory conditions that closely simulated those found in silica-depositing hot springs. Virus morphology was maintained, and a clear elemental signature of phosphorus was detected by energy-dispersive X-ray spectrophotometry (EDS).
Environmental Controls On The Landscape-Scale Biogeography Of Stream Bacterial Communities, Noah Fierer, Jennifer L. Morse, Sean T. Berthrong, Emily S. Bernhardt, Robert B. Jackson
Environmental Controls On The Landscape-Scale Biogeography Of Stream Bacterial Communities, Noah Fierer, Jennifer L. Morse, Sean T. Berthrong, Emily S. Bernhardt, Robert B. Jackson
Environmental Science and Management Faculty Publications and Presentations
We determined the biogeographical distributions of stream bacteria and the biogeochemical factors that best explained heterogeneity for 23 locations within the Hubbard Brook watershed, a 3000-ha forested watershed in New Hampshire, USA. Our goal was to assess the factor, or set of factors, responsible for generating the biogeographical patterns exhibited by microorganisms at the landscape scale. We used DNA fingerprinting to characterize bacteria inhabiting fine benthic organic matter (FBOM) because of their important influence on stream nutrient dynamics. Across the watershed, streams of similar pH had similar FBOM bacterial communities. Streamwater pH was the single variable most strongly correlated with …
Snow-Patch Influence On Soil Biogeochemical Processes And Invertebrate Distribution In The Mcmurdo Dry Valleys, Antarctica, Michael N. Gooseff, John E. Barrett, Peter T. Doran, Andrew G. Fountain, W. Berry Lyons, Andrew N. Parsons, Dorota L. Porazinska, Ross A. Virginia, Diana H. Wall
Snow-Patch Influence On Soil Biogeochemical Processes And Invertebrate Distribution In The Mcmurdo Dry Valleys, Antarctica, Michael N. Gooseff, John E. Barrett, Peter T. Doran, Andrew G. Fountain, W. Berry Lyons, Andrew N. Parsons, Dorota L. Porazinska, Ross A. Virginia, Diana H. Wall
Geography Faculty Publications and Presentations
The McMurdo Dry Valleys is the largest of the ice-free areas in Antarctica. Precipitation events in excess of 1 cm of snow accumulation are rare. During the winter, snow is transported by strong katabatic winds blowing from the polar plateau, and deposited into the lee of topographic features (e.g., stream channels and other topographic depressions). At the start of the austral summer (early October), as much as 10% of the valley soils may be covered by distributed snow patches. Because liquid water is the primary driver of biological, physical, and chemical processes in this polar desert, quantifying fluxes of water …
Indicators Of Nutrient Limited Plankton Growth In Lakes Near Mount Saint Helens, Washington, Kurt Davis Carpenter
Indicators Of Nutrient Limited Plankton Growth In Lakes Near Mount Saint Helens, Washington, Kurt Davis Carpenter
Dissertations and Theses
Several lakes located in the blast zone of the 1980 eruption of Mount St. Helens were studied to determine if the plankton in the lakes were limited in their growth by nitrogen or phosphorus availability. Long term nutrient enrichment experiments were performed on lake water from five lakes and measures of chlorophyll-a, carbon fixation, and nutrient uptake were used to evaluate the extent of limitation. Nutrient concentrations, ratios, and uptake from 14 lakes provided additional evidence for limitation by nitrogen and/or phosphorus. The physical, chemical, and biological characteristics of the lakes were also examined to monitor the return of these …