Biogeochemistry Commons^™

Using Emerging Methods To Investigate Stream And Groundwater Interaction At Multiple Spatial Scales, Martin Ashley Briggs

Earth & Environmental Sciences - Dissertations

Fundamentally, streams represent physical conduits of water across gradients, yet a more holistic definition reveals stream corridors support a mosaic of living communities in a blend of surface and ground waters. The physical and biogeochemical patterns these dynamic systems support affect natural habitat and water quality, directly impacting the human experience. Our understanding of stream and groundwater interactions is at a time of rapid expansion due to an increase in environmental awareness, accountability, and emerging techniques which can be used to decipher underlying controls and develop predictive relationships. Water temperature has been used as a qualitative environmental tracer during the …

Evaluation Of Electrophoretic Protein Extraction And Database-Driven Protein Identification From Marine Sediments, Eli K. Moore, Brook L. Nunn, Jessica F. Faux, David R. Goodlett, H. Rodger Harvey

OES Faculty Publications

Intact proteins comprise a major component of organic carbon and nitrogen produced globally and are likely an important fraction of organic matter in sediments and soils. Extracting the protein component from sediments and soils for mass spectral characterization and identification represents a substantial challenge given the range of products and functionalities present in the complex matrix. Multiple forms of gel electrophoresis were evaluated as a means of enhancing recovery of sedimentary protein before proteomic characterization and compared with a direct enzymatic digestion of proteins in sediments. Resulting tryptic peptides were analyzed using shotgun proteomics and tandem mass spectra were evaluated …

The Carbon Budget Impact Of Sagebrush Degradation, Andrew Connor Austreng

Boise State University Theses and Dissertations

More than 20,000 km2 of sagebrush (Artemesia spp.) ecosystems within the Great Basin have been replaced, often following wildfire, by the nonnative winter annual cheatgrass (Bromus tectorum). At a field site in the central Snake River Plain of southern Idaho, the impact of this invasion on the soil carbon (C) reservoir has been evaluated and the potential soil C benefits of bunchgrass (Agropyron cristatum) seeding was assessed. Using a large soil C dataset (n = 850), differences in total organic carbon and root biomass were quantified in immediately-adjacent sagebrush, cheatgrass, and bunchgrass communities. Statistical …

Natural And Constructed Wetlands For Ecosystem And Engineering Services In The Arid And Semi-Arid Regions, Achyut Raj Adhikari

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Las Vegas Wash (LVW) has undergone significant wetlands degradation and soil erosion over the past thirty years due to increasing flow resulting from urbanization and large rainfall events in the Las Vegas Valley Watershed. The increased flow and associated pollution load in the LVW and its adverse impact in Lake Mead have alerted stakeholders to pay a greater attention to explore alternative measures for rehabilitation of wetland ecosystems. This dissertation, using the case of changes in LVW, analyzes and describes ecological and engineering services provided by wetlands in arid and semi-arid regions and provides a knowledge base that can …

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 …

Phosphate Availability During Sediment Resuspension Events In The Great Bay Estuary, Taylor Langkau

Honors Theses and Capstones

Phosphate is an important nutrient to marine ecosystems such as the Great Bay Estuary. However, its bioavailability is limited due to its tendency to adsorb to marine sediments, especially iron oxides. This paper investigates phosphate dynamics during a simulated storm compared to calm conditions and aims to quantify the mechanisms of phosphate adsorption.

Water And Energy Balance Response Of A Riparian Wetland To The Removal Of Phragmites Australis, Phillip Mykleby

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Vegetation and climate both play integral roles in water availability, particularly for arid to semi-arid regions. Changes in these variables can lead to extreme shortages in water for regions that rely on water for crop irrigation (i.e., the Great Plains). The objective of this study is to evaluate the impacts of vegetation on water availability in the Republican River basin in central Nebraska. Decreases in streamflow have been observed in the river basin for many years and, as a result, an invasive riparian plant species (Phragmites australis) is being removed in an effort to reduce evapotranspiration and reclaim …

Permanganate Oxidizable Carbon Reflects A Processed Soil Fraction That Is Sensitive To Management, Steven W. Culman, Sieglinde S. Snapp, Mark A. Freeman, Meagan E. Schipanksi, Josh Beniston, Rattan Lal, Laurie E. Drinkwater, Alan J. Franzluebbers, Jerry D. Glover, A. Stuart Grandy, Juhwan Lee, Johan Six, Jude E. Maul, Steven B. Mirsky, John T. Spargo, Michelle M. Wander

Faculty Publications

Permanganate oxidizable C (POXC; i.e., active C) is a relatively new method that can quantify labile soil C rapidly and inexpensively. Despite limited reports of positive correlations with particulate organic C (POC), microbial biomass C (MBC), and other soil C fractions, little is known about what soil fractions POXC most closely reflects. We measured POXC across a wide range of soil types, ecosystems, and geographic areas (12 studies, 53 total sites, n = 1379) to: (i) determine the relationship between POXC and POC, MBC and soil organic C (SOC) fractions, and (ii) determine the relative sensitivity of POXC as a …

Nutrient And Fecal Microbe Assessment Of The Water Quality Of Tates Creek, Madison County, Kentucky, Walter S. Borowski, Kristopher H. Carroll

EKU Faculty and Staff Scholarship

Tates Creek is a significant tributary to the Kentucky River that has shown high levels of microbial and nutrient pollution in the past (Kentucky River Watershed Watch). We sampled the waters of Tates Creek more comprehensively by collecting stream water at 25 stations along its 13-mile length from its headwaters to the Kentucky River. Most samples were collected at the confluence of major tributaries to also access the water quality of tributary streams. Samples were collected four times between May and August 2011 during dry periods as well as immediately after a rainfall event. We measured ammonium (NH₄^{+ …}

Coupling Of Fog And Marine Microbial Content In The Near-Shore Coastal Environment, M. E. Ducker, Gregory D. O'Mullan, K. C. Weathers, A. R. Juhl, M. Uriarte

Publications and Research

Microbes in the atmosphere (microbial aerosols) play an important role in climate and provide an ecological and biogeochemical connection between oceanic, atmospheric, and terrestrial environments. However, the sources and environmental factors controlling the concentration, diversity, transport, and viability of microbial aerosols are poorly understood. This study examined culturable microbial aerosols from a coastal environment in Maine (USA) and determined the effect of onshore wind speed and fog presence on deposition rate, source, and community composition. During fog events with low onshore winds (

Sensitivity Analysis Of The Gems Soil Organic Carbon Model To Land Cover Land Use Classification Uncertainties Under Different Climate Scenarios In Senegal, Amadou M. Dieye, David P. Roy, N. P. Hanan, S. Lui, M. Hansen, A. Toure

GSCE Faculty Publications

Spatially explicit land cover land use (LCLU) change information is needed to drive biogeochemical models that simulate soil organic carbon (SOC) dynamics. Such information is increasingly being mapped using remotely sensed satellite data with classification schemes and uncertainties constrained by the sensing system, classification algorithms and land cover schemes. In this study, automated LCLU classification of multi-temporal Landsat satellite data were used to assess the sensitivity of SOC modeled by the Global Ensemble Biogeochemical Modeling System (GEMS). The GEMS was run for an area of 1560km2 in Senegal under three climate change scenarios with LCLU maps generated using different Landsat …

Chemical And Isotopic Evaluation Of Sulfur Sources And Cycling In The Pecos River, New Mexico, Usa, Fasong Yuan, Bernhard Mayer

Biological, Geological, and Environmental Faculty Publications

The use of stable isotopes in studies of watershed biogeochemical processes has increased greatly throughout the last several decades. Much of the sulfur cycling research has addressed the influence of changes in atmospheric acid deposition on sulfur dynamics in temperate ecosystems. Little is known about sulfur cycling in dryland ecosystems such as those in the American Southwest. To identify the sources and assess the cycling of sulfur in dryland ecosystems, chemical and isotopic compositions of water were measured on samples collected from the Pecos River (New Mexico, USA) during a reconnaissance survey in spring 2010. Based on the chemical and …

Exploring The Role Of Organic Matter Accumulation On Delta Evolution, Jorge Lorenzo Trueba, Vaughan Voller, Chris Paola, Robert Twilley, Azure Bevington

Department of Earth and Environmental Studies Faculty Scholarship and Creative Works

We explore the role of plant matter accumulation in the sediment column in determining the response of fluvial-deltas to base-level rise and simple subsidence profiles. Making the assumption that delta building processes operate to preserve the geometry of the delta plain, we model organic sedimentation in terms of the plant matter accumulation and accommodation (space made for sediment deposition) rates. A spatial integration of the organic sedimentation, added to the known river sediment input, leads to a model of delta evolution that estimates the fraction of organic sediments preserved in the delta. The model predicts that the maximum organic fraction …

Diversity, Distribution, And Expression Of Diazotroph Nifh Genes In Oxygen-Deficient Waters Of The Arabian Sea, Amal Jayakumar, Mamoon M. D. Al-Rshadat, Bess B. Ward, Margaret R. Mulholland

OES Faculty Publications

The Arabian Sea oxygen minimum zone (OMZ), the largest suboxic region in the world's oceans, is responsible for up to half of the global mesopelagic fixed nitrogen ( N ) loss from the ocean via denitrification and anammox. Dinitrogen (N₂) fixation is usually attributed to cyanobacteria in the surface ocean. Model prediction and physiological inhibition of N₂ fixation by oxygen, however, suggest that N₂ fixation should be enhanced near the oxygen-deficient zone (ODZ) of the Arabian Sea. N₂ fixation and cyanobacterial nifH genes (the gene encoding dinitrogenase reductase) have been reported in surface waters overlying …

Controls On Dissolved Cobalt In Surface Waters Of The Sargasso Sea: Comparisons With Iron And Aluminum, R. U. Shelley, Peter N. Sedwick, T. S. Bibby, P. Cabedo-Sanz, T. M. Church, R. J. Johnson, A. I. Macey, C. M. Marsay, E. R. Sholkovitz, S. J. Ussher, P. J. Worsfold, M. C. Lohan

OES Faculty Publications

Dissolved cobalt (dCo), iron (dFe) and aluminum (dAl) were determined in water column samples along a meridional transect (∼31°N to 24°N) south of Bermuda in June 2008. A general north-to-south increase in surface concentrations of dFe (0.3-1.6 nM) and dAl (14-42 nM) was observed, suggesting that aerosol deposition is a significant source of dFe and dAl, whereas no clear trend was observed. for near-surface dCo concentrations. Shipboard aerosol samples indicate fractional solubility values of 8-100% for aerosol Co, which are significantly higher than corresponding estimates of the solubility of aerosol Fe (0.44-45%). Hydrographic observations and analysis of time series rain …

H2/Ch4 Ratios Cannot Reliably Distinguish Abiotic Vs. Biotic Methane In Natural Hydrothermal Systems, Susan Q. Lang, G. L. Früh-Green, D. S. Kelley, M. D. Lilley, G. Proskurowski, E. P. Reeves

Faculty Publications

No abstract provided.

Implications Of Decade Time Scale Arctic Plant Community Change On Ecosystem Function, Mark Jason Lara

Open Access Theses & Dissertations

Almost half the global soil organic carbon pool is found in northern high latitudes. The majority of this soil carbon is stored in a greenhouse inert state within permafrost. As pronounced warming of high northern latitudes ensues, there is a strong likelihood that this substantial soil organic carbon pool will be mobilized to the atmosphere where it is likely to positively enhance greenhouse warming. Modeling studies suggest this positive feedback could alter future climate states of the Arctic and the globe, and affect how humans may need to adapt to climate change. Accordingly, understanding the patterns and controls and the …

The Impact Of Decadal Land Cover Change On The Global Warming Potential Of Beringian Arctic Tundra, David Hwei-Len Lin

Open Access Theses & Dissertations

Arctic terrestrial ecosystems play an important role in the global carbon cycle. If arctic warming continues to rise as projected, large amounts of soil carbon stored in these ecosystems could be released to the atmosphere as carbon dioxide or methane and positively enhance greenhouse warming. Thus, improving understanding of the likely future state and fate of arctic soil carbon, and the carbon uptake potential of arctic terrestrial ecosystems are well recognized research priorities.

At the pan-arctic scale, decadal increases in NDVI (Normalized Difference Vegetation Index), an index of vegetation productivity, have been observed from satellite imagery, indicating a general greening …

Landscape-Level Controls On Dissolved Carbon Flux From Diverse Catchments Of The Circumboreal, Suzanne E. Tank, Karen E. Frey, Robert G. Striegl, Peter A. Raymond, Robert M. Holmes, James W. Mcclelland, Bruce J. Peterson

Geography

While much of the dissolved organic carbon (DOC) within rivers is destined for mineralization to CO2, a substantial fraction of riverine bicarbonate (HCO3-) flux represents a CO2 sink, as a result of weathering processes that sequester CO2 as HCO 3-. We explored landscape-level controls on DOC and HCO3- flux in subcatchments of the boreal, with a specific focus on the effect of permafrost on riverine dissolved C flux. To do this, we undertook a multivariate analysis that partitioned the variance attributable to known, key regulators of dissolved C flux (runoff, lithology, and vegetation) prior to examining the effect of permafrost, …

New Science, Synthesis, Scholarship, And Strategic Vision For Society, David R. Foster, Emery Boose, Elizabeth A. Colburn, Elizabeth E. Crone, Aaron M. Ellison, Clarisse Hart, Kathy Fallon Lambert, David A. Orwig, Julie Pallant, Pamela M. Snow, Kristina A. Stinson, Dianna L. Doucette, Paul R. Moorcroft, Andrew D. Richardson, J. William Munger, Adrien C. Finzi, Lucy Hutyra, Anne Short, Brian Donahue, Christopher A. Williams, William V. Sobczak, W. Wyatt Oswald, Edward K. Faison, Jerry M. Melillo, Jonathan R. Thompson, Jeffrey L. Blanchard, Elizabeth S. Chilton, Kristen M. Deangelis, Stephen Destefano, David B. Kittredge, Serita D. Frey, Scott V. Ollinger, Eric A. Davidson

Faculty Publications

Harvard Forest LTER (HFR) is a two decade-strong, integrated research and educational program investigating responses of forest dynamics to natural and human disturbances and environmental changes over broad spatial and temporal scales. HFR engages >30 researchers, >200 graduate and undergraduate students, and dozens of institutions in research into fundamental and applied ecological questions of national and international relevance. Through LTER I–IV, HFR has added historical perspectives, expanded its scope to the New England region, integrated social, biological, and physical sciences, and developed education and outreach programs for K-12, undergraduate, and graduate students, along with managers, decision-makers, and media professionals.

Variability In Hydrology And Ecosystem Properties And Their Role In Regulating Soil Organic Matter Stability In Wetlands Of West-Central Florida, Sharon Jean Feit

USF Tampa Graduate Theses and Dissertations

Soil organic matter (SOM) provides many ecosystem services that are necessary for continued ecosystem function. The accumulation of SOM in an ecosystem is a function of its persistence time which can range from days to thousands of years. Ecosystem properties including dominant vegetation type, soil texture, and soil moisture in various habitats can regulate the persistence time of SOM.

Wetlands, because of their associated ecosystem properties, promote SOM accumulation, but little has been done to determine the ecosystem properties that regulate its persistence over time. In west-central Florida, urbanization and increased water demands have suppressed water tables in isolated wetland …

Nitrogen Retention And Denitrification In Reservoirs, Erin Grantz

Graduate Theses and Dissertations

Studies coupling direct measurements of micro-scale nitrogen (N) cycle processes with ecosystem-scale flux estimates are needed to determine N retention hotspots within river networks, where up to 50% of terrestrial loading to aquatic systems is retained. This study examined the role of denitrification, a microbially-mediated reactive N removal pathway, in ecosystem-scale N retention in 3 small (< 1 km2), shallow flood-control reservoirs. Annual reservoir N retention was estimated through mass balance modeling of system inputs and outputs. Annual denitrification rates were estimated by combining multiple measurements of seasonal, habitat-specific dinitrogen gas (N2) fluxes. Annual reservoir N retention ranged from 14 - 19 g m-2 in the reservoirs, while reactive N removal through denitrification was 13 - 25 g m-2. Denitrification efficiency, or the portion of the retained N load that was denitrified, was high relative to other lentic systems and was > 100% at 2 sites. Previous lentic denitrification studies may have underestimated denitrification efficiency by not considering water column denitrification, which was 50% of total denitrification at one study reservoir. However, not all potential inputs, most importantly biological N2 fixation, were included in this …

Nutrient And Fecal Microbe Assessment Of The Water Quality Of Tates Creek, Madison County, Kentucky, Krisopher H. Carroll, Walter S. Borowski

EKU Faculty and Staff Scholarship

Tates Creek is a significant tributary to the Kentucky River that has shown high levels of microbial and nutrient pollution. We sampled the waters of Tates Creek comprehensively by occupying 25 stations along its 13-mile length, collecting stream water at the confluence of major tributaries from its headwaters to the Kentucky River. Samples were collected four times between May and August 2011 during dry periods as well as immediately after rainfall events.

We measured ammonium (NH₄⁺), nitrate (NO₃^-) and phosphate (PO₄^-) concentrations using colorimetry. Microbial samples were measured for total coliform …

Quantification Of Nitrate Sources And Sinks Using A Water Quality Network In Morro Bay Estuary, California, Johanna Nadia Jean Weston

Master's Theses

Using an instrumented water quality network in Morro Bay Estuary, California from 2007 to 2010 (15 min sampling frequency), this study addressed the two objectives of constructing a nitrate budget and assessing the influence of sampling frequency on water quality parameters. These two objectives led to the submission of an original report of research (Appendix A) and a note (Appendix B) to peer-reviewed journals.

The first objective was to characterize the high spatial and temporal variation in physical parameters and nitrate concentrations and to construct a nitrate budget quantifying sources and sinks of nitrate from the ocean, streams, and groundwater, …

Effect Of Reworking And Bioturbation On Sedimentary Reactive Iron Within A Microtidal Estuary, Amy Kathleen Pitts

OES Theses and Dissertations

Mixed redox conditions in sediments due to physical reworking may allow for enhanced remineralization of refractory organic matter due to Fe(III) redox cycling. In part this may occur because easily reducible iron oxides can be used by heterotrophic bacteria to remineralize the organic carbon. This phenomena has been observed in bioturbated sediments and in areas where physical factors (such as strong bottom currents) constantly rework the sediments. To specifically determine the effects of physical reworking and bioturbation on concentrations of easily reducible iron oxides, reactive iron concentrations were measured in surface sediments taken from two contrasting sites in the York …

Stromatolitic Knobs In Storrs Lake, San Salvador, Bahamas: Insights Into Organomineralization, Alexandre J. Fowler

Master's Theses

Storrs Lake, a hypersaline lake on the east coast of San Salvador Island, Bahamas, contains well-developed microbial mats, some of which have developed calcified structures called microbialites. Many of these microbialites are laminated, and therefore classified as stromatolites. This study focuses on small stromatolitic knobs located in the southern portion of Storrs lake, which are still actively forming, to gain insights into the early stages of stromatolite formation. These knobs appear to be forming as the result of in situ micritic precipitation mediated by both photosynthetic and heterotrophic microbial metabolisms. By comparing these small stromatolitic knobs to larger stromatolitic heads …

Biological Effects On Serpentinite Weathering, Mary H. Evert, Julie Baumeister, Elisabeth Hausrath

Undergraduate Research Opportunities Program (UROP)

Serpentinites, perhaps more than any other rock type, control the composition and evolution of the development of the surrounding ecosystems. The bulk chemistry of serpentinite rocks, high in Mg and trace elements, and low in nutrients such as Ca, K, P, and N, causes an extreme and stressful environment for ecosystems. However, the role that those serpentine ecosystems play in development of serpentine soils has not been examined.

Due to the unusual chemistry of serpentine soils, serpentine ecosystems have deeper and better-developed root systems than other ecosystems. The rhizosphere of serpentine systems, documented to produce abundant organic acids and siderophores, …

Relationships Between Snow Pack, Soil Moisture, And Forest Greenness: Implications For Smap, Jordan Anderson, Noah Molotch, Bin Guan

STAR Program Research Presentations

Snowpack in the arid/semi-arid western United States is a critical element of the hydrologic cycle as water is stored in the winter and released in the spring and summer. The warmer seasons rely heavily on this water source for various purposes including economic (farming), environmental and recreational demands. Moderate Imaging Spectroradiometer (MODIS) sensors were used in this project to measure seasonal variability in global vegetation phenology and productivity. MODIS data was used to calculate Normalized Difference Vegetation Index (NDVI) to estimate net primary production of subalpine forests in the Sierra Nevada mountain range. Preliminary results indicate that variability in forest …

No-Net-Loss Not Met For Nutrient Function In Freshwater Marshes: Recommendations For Wetland Mitigation Policies, Katie Hossler, Virginie Bouchard, M. Siobhan Fennessy, Serita D. Frey, Evelyn Anemaet, Ellen Herbert

Faculty Publications

Wetlands provide many important services throughout the world, with an estimated economic value that, in comparison to other ecosystems, far exceeds their relatively small global extent. In recognition of their importance, both national and international regulations exist to protect the world's remaining wetlands. Of growing interest is the “no-net-loss” policy which permits unavoidable destruction of wetlands if compensated by restoration of degraded wetlands or creation of new wetlands. The fundamental assumption of no-net-loss is that wetlands can be created which function equivalently to natural wetlands. One integral function that wetlands perform is cycling of carbon, nitrogen and phosphorus. Here we …

Evaluation Of The Carbon Budgets In The Forested And Agricultural Soils Of The Semi-Arid Mogollon-Datil Highlands And Rio Grande Basin, Ryan Reeves^, Lixin Jin*

COURI Symposium Abstracts, Summer 2011

No abstract provided.