Thesis
Effects of storm size and frequency on nitrogen retention, denitrification, and greenhouse gas production bioretention mesocosms
Washington State University
Master of Science (MS), Washington State University
2016
Handle:
https://hdl.handle.net/2376/103661
Abstract
Bioretention swales have shown wide ranging nitrogen (N) retention efficiencies, and no studies have measured denitrification or examined its importance across storm sizes and frequencies. We used experimental mesocosms to examine effects of storm size on N processing. We compared N dynamics during large storms (3.05 cm d-1 ) seen in the current climate, with those during the precipitation events expected to accompany climate change (5.08 cm d-1 ). Following an initialization storm, we tested latency periods of 1-day, 7-days, and 13-days. While storms occurring after 7-days of latency (520 ± 150 µmol N m-2 hr-1 ) had significantly higher denitrification rates than occurred during an initialization storm (13 ± 34 µmol N m-2 hr-1 ) or during a storm following 1-day of latency (-63 ± 65 µmol N m-2 hr-1 ), no significant differences in N processing were observed between storm sizes. Surprisingly, [O2] remained near saturated, and N2O emissions were practically non-existent. Mesocosms were largely a net sink for dissolved inorganic N (DIN) and a net source of dissolved organic N (DON). Denitrification was neither a dominant nor consistent pathway for N removal in bioretention swales, accounting for a maximum of 23 ± 11% of DIN removal. Nevertheless, denitrification can account for a substantial fraction of DIN removal even in soils that appear well-oxygenated. Future research should further develop N mass balances in bioretention systems and examine the role of consecutive storm events, anaerobic microsites, and denitrification between storm events
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Details
- Title
- Effects of storm size and frequency on nitrogen retention, denitrification, and greenhouse gas production bioretention mesocosms
- Creators
- Richard Albert Norton
- Contributors
- John A. Harrison (Degree Supervisor)
- 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; [Pullman, Washington] :
- Identifiers
- 99900525190301842
- Language
- English
- Resource Type
- Thesis