Denitrification in Agricultural Surface Waters: Quantifying the Effect of Environmental Parameters and Hydrologic Connectivity on Nitrate Uptake and Microbial Communities
2017-10
Loading...
View/Download File
Persistent link to this item
Statistics
View StatisticsJournal Title
Journal ISSN
Volume Title
Title
Denitrification in Agricultural Surface Waters: Quantifying the Effect of Environmental Parameters and Hydrologic Connectivity on Nitrate Uptake and Microbial Communities
Authors
Published Date
2017-10
Publisher
Type
Thesis or Dissertation
Abstract
The development of synthetic fertilizer has led to increases in crop yields and allowed for global population growth over the past century. However, this increase in available nitrogen has greatly altered the global nitrogen cycle, including increased nitrate loading to surface water and groundwater in the Midwestern United States, with negative effects on human health and aquatic ecosystems. Therefore, there is a need for effective management strategies and an understanding of the mechanisms for nitrate transport and uptake. Denitrification, the microbiological reduction of nitrate to nitrogen gas, can be viewed as a net sink for reactive nitrogen in aquatic systems. Small areas, termed hot spots, and short time periods, termed hot moments, frequently account for a large portion of denitrification. This research focuses on identifying the environmental parameters and hydrologic regimes that promote denitrification, along with determining how parameters, denitrification rates, and microbiological communities are related at multiple temporal and spatial scales. At the finest scale, a recirculating laboratory flume was used to determine the effect of turbulence and organic carbon on denitrification rates and the microbial community. An outdoor experimental stream and flow-through basin in the Outdoor StreamLab at the St. Anthony Falls Laboratory (SAFL) were used to determine the effect of short-term inundation and periodic inundation on denitrification. At the largest scale, water and sediment samples were collected over two years from a field site in an agricultural watershed in Southern Minnesota. The objectives of this research were to: (1) determine how turbulence and organic carbon affect denitrification, (2) investigate how inundation and hydrologic connectivity leads to the formation of denitrification hot spots and hot moments, (3) quantify and correlate the driving environmental parameters of microbial denitrification and the differences in these relationships for in-channel and riparian locations in an agricultural watershed, (4) develop and evaluate functional relationships between environmental parameters and denitrification rates, and (5) identify how denitrifying gene abundances, denitrification rates, and environmental parameters are related across a hydrologic gradient from channels to riparian areas.
Description
University of Minnesota Ph.D. dissertation. October 2017. Major: Civil Engineering. Advisor: Miki Hondzo. 1 computer file (PDF); xii, 190 pages.
Related to
Replaces
License
Collections
Series/Report Number
Funding information
Isbn identifier
Doi identifier
Previously Published Citation
Suggested citation
Tomasek, Abigail. (2017). Denitrification in Agricultural Surface Waters: Quantifying the Effect of Environmental Parameters and Hydrologic Connectivity on Nitrate Uptake and Microbial Communities. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/192683.
Content distributed via the University Digital Conservancy may be subject to additional license and use restrictions applied by the depositor. By using these files, users agree to the Terms of Use. Materials in the UDC may contain content that is disturbing and/or harmful. For more information, please see our statement on harmful content in digital repositories.