Thesis
Estimation of the Contribution of Biological Nitrogen Fixation to the Nitrogen Budget in a Freshwater Lake
Washington State University
Master of Science (MS), Washington State University
2023
DOI:
https://doi.org/10.7273/000005357
Abstract
Nitrogen (N) is an essential nutrient for all organisms. A lack of N can limit primary production, but an excess of N can cause harmful algal blooms and consequences to freshwater quality. Freshwater environments contain N fixing organisms whose contribution to the N cycle through organic inputs remains unclear because their N fixation rates and controls are understudied. Without knowing how much N comes into the freshwater ecosystem from fixation, it is difficult to fully understand food webs, N cycling and difficult to manage nutrient pollution. This research addressed the question of how much N fixation contributes to the N budget of a freshwater lake in northeast Washington State. We measured N fixation rates in cyanobacteria and sediment bacteria using a 15N2 tracer method during an in-lab incubation. No correlation was found between N fixation rates and the environment’s temperature, dissolved oxygen (mg/L), percent dissolved oxygen, pH, conductivity, nor total N and total phosphorus (P) water concentrations. However, a slight positive relationship between N:P rates in the water’s surface and N fixation was observed. Although the rates we measured were extremely low, we still found that the contribution of N from lake diazotrophs was similar to that of N inputs coming from allochthonous sources during autumn, suggesting that N fixation is seasonally important.
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Details
- Title
- Estimation of the Contribution of Biological Nitrogen Fixation to the Nitrogen Budget in a Freshwater Lake
- Creators
- Riley Ann Baxter
- Contributors
- Sarah S. Roley (Advisor)Barry C. Moore (Committee Member)Gretchen Rollwagen-Bollens (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Environment, School of the (CAHNRS)
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Number of pages
- 51
- Identifiers
- 99901031240201842
- Language
- English
- Resource Type
- Thesis