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Articles 1 - 14 of 14
Full-Text Articles in Biogeochemistry
High Algal Biomass Is Decoupled From Metabolism In The Gallatin River, Cora Mae Steinbach
High Algal Biomass Is Decoupled From Metabolism In The Gallatin River, Cora Mae Steinbach
Graduate Student Theses, Dissertations, & Professional Papers
Assessing eutrophication in rivers is difficult compared to lakes and coastal waters, because most algal biomass occurs on the riverbed and flows interact and co-vary with production (Biggs and Close, 1989; Bernhardt et al., 2018). Riverine eutrophication is typically assessed using algal biomass and water column nutrients (U.S. Environmental Protection Agency, 2000), but biomass is highly variable and labor-intensive to measure, while nutrient concentrations often underestimate enrichment due to rapid biological uptake (Dodds and Smith, 2016). Reach-scale river metabolism can help evaluate long-term functional change in rivers recovering from nutrient enrichment (Arroita et al., 2019; Jankowski et al., 2021; Diamond …
Beaver Dam Analogs (Bdas) Alter Carbon Pools, Fluxes, And Concentrations Of Intermountain Headwater Streams, Hilary Schultz
Beaver Dam Analogs (Bdas) Alter Carbon Pools, Fluxes, And Concentrations Of Intermountain Headwater Streams, Hilary Schultz
Graduate Student Theses, Dissertations, & Professional Papers
Beaver dam analogs (BDAs) have emerged as a climate adaptation and restoration strategy for water resource management in the drought-prone Western U.S., yet the focus has been on their influence on water quantity, overlooking effects on broader ecological components. By increasing water residence time and facilitating sediment retention, BDAs have the potential to influence carbon pools, fluxes, and concentrations. To examine the influence of BDAs on instream and riparian organic C and trace gases, we studied three intermountain headwater streams restored with BDAs two years after restoration during the summer of 2021. We found that there were subtle differences in …
Combined Effects Of Temperature And Heavy Metals On The Performance Of The Giant Salmonfly., James Frakes, Amanda Andreas, Benjamin P. Colman, Aurthur Woods
Combined Effects Of Temperature And Heavy Metals On The Performance Of The Giant Salmonfly., James Frakes, Amanda Andreas, Benjamin P. Colman, Aurthur Woods
Graduate Student Theses, Dissertations, & Professional Papers
In many freshwater ecosystems, communities of aquatic insects are facing the combined stresses of warmer waters due to climate change and increased exposure to heavy metal toxicants. Although each stressor may threaten aquatic insects independently, they also likely interact in important ways to affect insect physiology and performance. Here we investigate this potential interaction using two populations of aquatic nymphs of the giant salmonfly, Pteronarcys californica, collected from adjacent rivers in Montana: naïve individuals from Rock Creek, a relatively pristine stream, and individuals from the Upper Clark Fork River, which has a history of heavy metal pollution and higher …
Nitrogen Dynamics And Transport Along Flowpaths In A Rural Wetland-Stream Complex, Colton Kyro
Nitrogen Dynamics And Transport Along Flowpaths In A Rural Wetland-Stream Complex, Colton Kyro
Graduate Student Theses, Dissertations, & Professional Papers
Human activities have doubled the rate of nitrogen inputs onto the landscape resulting in elevated nitrogen concentrations in our streams. Anthropogenically applied nitrogen is largely transported to stream networks via groundwater movement. Groundwater discharge occurs in distinct points along a stream but whose influences can often persist far beyond that area due to insufficient biogeochemical removal of imported nitrogen potentially causing alterations in community structure and precipitating large algae blooms. To understand the factors governing nitrogen abundance in a historical polluted stream, I used a mass-balance approach to quantify groundwater-surface water interaction and the magnitude of groundwater nitrogen input and …
Modeling Stromatolite Formation With Diffusion-Limited Aggregation, Laura E. Stevens
Modeling Stromatolite Formation With Diffusion-Limited Aggregation, Laura E. Stevens
Graduate Student Theses, Dissertations, & Professional Papers
Stromatolites, microbialites, and other microbially induced sedimentary structures exist in the rock record as far back as 3.6 billion years ago and continue to form in the present day. Better characterizing these structures and better understanding how they form is crucial in distinguishing these biosignatures from similar, abiotic structures, which can help us to understand the conditions of early Earth and early Mars. To that end, I have modified DLA 3D EXT, an open-source stromatolite modeling program, to more closely reflect the process of microbial trapping-and-binding by filamentous microbes in a calcite-precipitating hot spring system. This modified program includes a …
Using Satellite Observations Of Soil Moisture To Improve Modeling Of Terrestrial Water Cycles, Colin W. Brust
Using Satellite Observations Of Soil Moisture To Improve Modeling Of Terrestrial Water Cycles, Colin W. Brust
Graduate Student Theses, Dissertations, & Professional Papers
Terrestrial evapotranspiration (ET) describes the flux of water from the Earth’s surface to the atmosphere, calculated as the sum of evaporation from soil and leaf surfaces, and transpiration through plant stomata. ET is the largest terrestrial water flux, returning over half of the precipitation that falls on land back to the atmosphere, annually. Additionally, ET plays a key role in Earth’s carbon, water, and energy cycles, linking them together via the movement of water and CO2 through plant stomata. Because of its important role in these Earth system processes, it is essential that existing methods of measuring and modeling …
Understanding And Measuring Net Positive Business Strategies, Luke Ruffner Robinson
Understanding And Measuring Net Positive Business Strategies, Luke Ruffner Robinson
Graduate Student Theses, Dissertations, & Professional Papers
Despite their attempts to mitigate ecological impacts through sustainability initiatives, businesses are a major cause of the world's ecological problems. Some progressive businesses are attempting to move beyond “net zero” in terms of achieving neutral environmental impacts and instead are now pursuing a goal of net positive. Net positive refers to the idea that business activities could contribute value-added benefits to earth’s ecological systems, for example, by using technologies that sequester and store carbon. However, except for a handful of high-profile corporate case studies, little is known about how companies are developing their strategies to become net positive and …
Spatiotemporal Dynamics Of Nitrogen And Carbon Biogeochemistry In A Wetland-Stream Sequence, Patrick E. Hurley
Spatiotemporal Dynamics Of Nitrogen And Carbon Biogeochemistry In A Wetland-Stream Sequence, Patrick E. Hurley
Graduate Student Theses, Dissertations, & Professional Papers
Studies of aquatic ecosystems often segregate streams from the influential ponds, lakes, and wetland zones that act as important transitions between terrestrial and fluvial systems. Across the aquatic landscape, these zones interact to form linked ecosystems that function as discrete nutrient processing domains, shifting biogeochemical signals due to spatial and temporal variability in hydrologic and biologic controls. Using a mass-balance approach, we profiled nutrient dynamics along a 23-km wetland-stream sequence over three seasons. Hydrologic, morphologic, and biologic conditions, as well as landscape attributes, were quantified to determine potential controls on biogeochemical cycling in a tributary of the Upper Clark Fork …
Colloidal And Truly Dissolved Metal(Loid)S In Wastewater Lagoons And Their Removal With Floating Treatment Wetlands, Lauren Sullivan
Colloidal And Truly Dissolved Metal(Loid)S In Wastewater Lagoons And Their Removal With Floating Treatment Wetlands, Lauren Sullivan
Graduate Student Theses, Dissertations, & Professional Papers
Climate change is predicted to cause continuing declines in late-season streamflow, thus increasing the relative contribution of wastewater effluent to surface water flows. Wastewater effluent represents a critical point source of metal and metalloid contamination to aquatic ecosystems and wastewater lagoons are the most common wastewater treatment system in the rural United States. Although the fraction of total wastewater metals and metalloids in "dissolved" forms (defined here asnm) likely drives the potential for negative effects on receiving waters, this broad operational definition lumps truly dissolved solutes (nm) with small colloids and nanomaterials (1-450 nm; hereafter colloids). This size distinction may …
Synthesis Of Satellite Microwave Observations For Monitoring Global Land-Atmosphere Co2 Exchange, Lucas Alan Jones
Synthesis Of Satellite Microwave Observations For Monitoring Global Land-Atmosphere Co2 Exchange, Lucas Alan Jones
Graduate Student Theses, Dissertations, & Professional Papers
This dissertation describes the estimation, error quantification, and incorporation of land surface information from microwave satellite remote sensing for modeling global ecosystem land-atmosphere net CO2 exchange. Retrieval algorithms were developed for estimating soil moisture, surface water, surface temperature, and vegetation phenology from microwave imagery timeseries. Soil moisture retrievals were merged with model-based soil moisture estimates and incorporated into a light-use efficiency model for vegetation productivity coupled to a soil decomposition model. Results, including state and uncertainty estimates, were evaluated with a global eddy covariance flux tower network and other independent global model- and remote-sensing based products.
Is Atmospheric Phosphorus Pollution Altering Global Alpine Lake Stoichiometry?, Janice Brahney, Natalie Mahowald, Daniel S. Ward, Ashley P. Ballantyne, Jason C. Neff
Is Atmospheric Phosphorus Pollution Altering Global Alpine Lake Stoichiometry?, Janice Brahney, Natalie Mahowald, Daniel S. Ward, Ashley P. Ballantyne, Jason C. Neff
Ecosystem and Conservation Sciences Faculty Publications
Anthropogenic activities have significantly altered atmospheric chemistry and changed the global mobility of key macro-nutrients. Here we show that contemporary global patterns in nitrogen (N) and phosphorus (P) emissions drive large hemispheric variation in precipitation chemistry. These global patterns of nutrient emission and deposition (N:P) are in turn closely reflected in the water chemistry of naturally oligotrophic lake (r2 = 0.81, p < 0.0001). Observed increases in anthropogenic N deposition play a role in nutrient concentrations (r2 = 0.02, p < 0.05); however, atmospheric deposition of P appears to be major contributor to this pattern (r2 = 0.65, p < 0.0001). Atmospheric simulations indicate a global increase in P deposition by 1.4 times the pre-industrial rate largely due to increased dust and biomass burning emissions. Although changes in the mass flux of global P deposition are smaller than for N, the impacts on primary productivity may be greater because, on average, one unit of increased P deposition has 16 times the influence of one unit of N deposition. These stoichiometric considerations, combined with the evidence presented here, suggest that increases in P deposition may be a major driver of alpine Lake trophic status, particularly in the Southern Hemisphere. These results underscore the need for the broader scientific community to consider the impact of atmospheric phosphorus deposition on the water quality of naturally oligotrophic lakes.
Analysing The Spatio-Temporal Impacts Of The 2003 And 2010 Extreme Heatwaves On Plant Productivity In Europe, A. Bastos, C. M. Trigo, R. M. Trigo, Steven W. Running
Analysing The Spatio-Temporal Impacts Of The 2003 And 2010 Extreme Heatwaves On Plant Productivity In Europe, A. Bastos, C. M. Trigo, R. M. Trigo, Steven W. Running
Ecosystem and Conservation Sciences Faculty Publications
In the last decade, Europe has been stricken by two outstanding heatwaves, the 2003 event in western Europe and the 2010 episode over Russia. Both events were characterized by record-breaking temperatures and widespread socioeconomic impacts, including significant increments on human mortality, decreases in crop yields and in hydroelectric production. Previous works have shown that an extreme climatic event does not always imply an extreme response by ecosystems. This work attempts to assess how extreme was the vegetation response to the heatwaves during 2003 and 2010 in Europe, in order to quantify the impacts of the two events on carbon fluxes …
Climate-Mediated Nitrogen And Carbon Dynamics In A Tropical Watershed, Ashley P. Ballantyne, P. A. Baker, S. C. Fritz, B. Poulter
Climate-Mediated Nitrogen And Carbon Dynamics In A Tropical Watershed, Ashley P. Ballantyne, P. A. Baker, S. C. Fritz, B. Poulter
Ecosystem and Conservation Sciences Faculty Publications
Climate variability affects the capacity of the biosphere to assimilate and store important elements, such as nitrogen and carbon. Here we present biogeochemical evidence from the sediments of tropical Lake Titicaca indicating that large hydrologic changes in response to global glacial cycles during the Quaternary were accompanied by major shifts in ecosystem state. During prolonged glacial intervals, lake level was high and the lake was in a stable nitrogen-limited state. In contrast, during warm dry interglacials lake level fell and rates of nitrogen concentrations increased by a factor of 4–12, resulting in a fivefold to 24-fold increase in organic carbon …
Apparent Seasonal Cycle In Isotopic Discrimination Of Carbon In The Atmosphere And Biosphere Due To Vapor Pressure Deficit, Ashley P. Ballantyne, J. B. Miller, P. P. Tans
Apparent Seasonal Cycle In Isotopic Discrimination Of Carbon In The Atmosphere And Biosphere Due To Vapor Pressure Deficit, Ashley P. Ballantyne, J. B. Miller, P. P. Tans
Ecosystem and Conservation Sciences Faculty Publications
We explore seasonal variability in isotopic fractionation by analyzing observational data from the atmosphere and the biosphere, as well as simulated data from a global model. Using simulated values of atmospheric CO2 and its carbon isotopic composition, we evaluated different methods for specifying background concentrations when calculating the isotopic signature of source CO2 (δs) to the atmosphere. Based on this evaluation, we determined that free troposphere measurements should be used when available as a background reference when calculating δs from boundary layer observations. We then estimate the seasonal distribution of δs from monthly …