Physical Sciences and Mathematics Commons^™

Understanding The Impacts Of Freshwater Fluxes On The Biogeochemistry Of The Coastal Arctic: A Case Study Of Prudhoe Bay, Francesca Lingo

Dissertations and Theses

The Arctic region, undergoing significant environmental changes due to rapid warming, faces alterations in air temperatures, melting permafrost, declining sea ice, and changes in riverine inputs. These shifts have profound implications for Arctic coastal ecology and biogeochemical cycles. This study, focusing on Alaska's North Slope, explores the influence of freshwater fluxes on water optical properties, vital for accurate satellite remote sensing interpretations. Our approach combined field measurements, existing data, and satellite remote sensing retrievals to identify biogeochemical gradients and their seasonal and interannual variations. A novel finding was the unique CDOM composition in Prudhoe Bay, characterized by a lower molecular …

Effects Of Acid Deposition And Changing Climate On The Hydrochemistry And Critical Loads Of Watersheds In The Adirondack Region Of New York, Shuai Shao

Dissertations - ALL

Despite decreases in acidic deposition since the 1970s, the recovery of surface waters from acidification has been limited primarily due to the depletion of exchangeable base cations, net mineralization of organic sulfur and nitrogen and release of previously retained SO42- and NO3-, and increases in concentrations of naturally occurring organic acids from soil. The future recovery of stream chemistry from acidic deposition may be altered by projected increases in temperature and precipitation associated with a changing climate. The goals of this study were to conduct a modeling analysis of the response of soils and streams in the Adirondack Park, New …

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 …

Modeling Holocene Peatland Carbon Accumulation In North America, Qianlai Zhuang, Sirui Wang, Bailu Zhao, Filipe Aires, Catherine Prigent, Zicheng Yu, Jason K. Keller, Scott Bridgham

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Peatlands are a large carbon reservoir. Yet the quantification of their carbon stock still has a large uncertainty due to lacking observational data and well‐tested peatland biogeochemistry models. Here, a process‐based peatland model was calibrated using long‐term peat carbon accumulation data at multiple sites in North America. The model was then applied to quantify the peat carbon accumulation rates and stocks within North America over the last 12,000 years. We estimated that 85–174 Pg carbon was accumulated in North American peatlands over the study period including 0.37–0.76 Pg carbon in subtropical peatlands. During the period from 10,000 to 8,000 years …

Applications Of Reservoir Limnology Theory And Steady-State Modeling To Eutrophication Management In Beaver Lake, Arkansas, Matthew Rich

Graduate Theses and Dissertations

Reservoir limnology theory predicts that phytoplankton biomass (PB) is greatest in riverine-transition zones and least in lacustrine zones leading to an inverse pattern in water clarity. These theoretical patterns were utilized to create a statistical model of chlorophyll-a (Chl-a), an indicator of PB, and Secchi transparency (ST), an indicator of Chl-a, in Beaver Lake, Arkansas, a 12,800-ha reservoir, in order to hindcast historical conditions. Sampling for Chl-a, ST, and photic depth occurred semimonthly at 12 locations along a 78-km transect from the river inflow to the dam during the 2015 growing season. The ratio of Chl-a and ST measured at …

Soed Open Course: Seamless Modeling From Creek To Ocean On Unstructured Grids, Y. Joseph Zhang

Miscellaneous

This course explains the basic formulations used in the cross-scale SCHISM model, including the recent new developments. Hands-on tutorials will be conducted to familiarize the trainees with the basic tools useful for the modeling system. Although no formal pre-requisites are expected, trainees with prior UG model experience may find it easier to learn. Upon completion the trainees will have acquired basic knowledge on workflow in typical SCHISM simulations and be able to conduct simulations for cross-scale baroclinic processes as found in geophysical fluid dynamics (GFD)

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Toward “Optimal” Integration Of Terrestrial Biosphere Models, Christopher R. Schwalm, Deborah N. Huntzinger, Joshua B. Fisher, Anna M. Michalak, Kevin Bowman, Philippe Ciais, Robert Cook, Bassil El-Masri, Daniel Hayes, Maoyi Huang, Akihiko Ito, Atul Jain, Anthony W. King, Hiumin Lei, Junjie Liu, Chaoqun (Crystal) Lu, Jaifu Mao, Shushi Peng, Benjamin Poulter, Daniel Ricciuto, Kevin Schaefer, Xiaoying Shi, Bo Tao, Hanqin Tian, Weile Wang, Yaxing Wei, Jia Yang, Ning Zeng

Chaoqun (Crystal) Lu

Multimodel ensembles (MME) are commonplace in Earth system modeling. Here we perform MME integration using a 10-member ensemble of terrestrial biosphere models (TBMs) from the Multiscale synthesis and Terrestrial Model Intercomparison Project (MsTMIP). We contrast optimal (skill based for present-day carbon cycling) versus naïve (“one model-one vote”) integration. MsTMIP optimal and naïve mean land sink strength estimates (−1.16 versus −1.15 Pg C per annum respectively) are statistically indistinguishable. This holds also for grid cell values and extends to gross uptake, biomass, and net ecosystem productivity. TBM skill is similarly indistinguishable. The added complexity of skill-based integration does not materially change …

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 …