Thesis
Seasonal patterns and trends of carbon, nitrogen, and greenhouse gases (CO₂, CH₄, N₂O) in a semi-arid agricultural stream
Washington State University
Master of Science (MS), Washington State University
2013
Handle:
https://hdl.handle.net/2376/102632
Abstract
Small streams are sources of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) (collectively GHGs) to the atmosphere, with inland waters accounting for 25 to 79 % of terrestrial net ecosystem production (NEP) through CO2 and CH4 emissions, and ~10 % of anthropogenic N2O emissions. Few studies have co-measured these three major greenhouse gas emissions from streams, especially in human dominated systems such as in agricultural streams, making it difficult to determine the relative contribution of each GHG from small streams, and the degree to which they have similar or differing drivers. To better understand controls, and the amount of C, N and GHGs contributed from agricultural streams, CO2, CH4 and N2O concentrations and fluxes were measured along Missouri Flat Creek (MFC) located in southeastern Washington State, USA, between July 2011 and July 2012, along with nitrate (NO3 - ) and dissolved organic carbon (DOC). Between 90 to 95 % of all C and N was transported and GHGs evaded from MFC between January and May. When NO3 - -N and DOC-C mass discharges were scaled to the MFC watershed area, monthly average mass flux ranged from < 0.1 to 12 kg NO3 - -N ha-1 mo-1 , and < 0.1 to 0.7 kg DOC-C ha-1 mo-1 . Average GHG evasion fluxes ranged from -0.0015 to 2.3 g CO2-C m-2 hr-1 , 0.011 to 12 mg CH4-C m-2 hr-1 , and v -0.59 to 650 µg N2O-N m-2 hr-1 . GHG concentrations correlated with stream water temperature, dissolved oxygen (DO), pH, DOC-C, and NO3 - -N, but were highly variable between study sites along the MFC and during the study period. The source of GHGs in MFC are from terrestrial and in-stream processes. Seasonal patterns in the MFC indicate that the majority of GHGs emitted are most likely terrestrially derived. Seasonal magnitude of the origin of GHGs evaded from headwater streams may depend heavily on climate, precipitation patterns, hydrologic timing, temperature, C and N availability, biological activity, and land use. This study supports the idea that the release of CO2 and CH4 from inland waters is connected to terrestrial NEP.
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Details
- Title
- Seasonal patterns and trends of carbon, nitrogen, and greenhouse gases (CO₂, CH₄, N₂O) in a semi-arid agricultural stream
- Creators
- Leif G. Moon-Nielsen
- Contributors
- Cailin Huyck Orr (Chair)Raymond David Evans (Committee Member)Chester Kent Keller (Committee Member) - Washington State University, Environment, School of the (CAS)
- 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
- 99900525003701842
- Language
- English
- Resource Type
- Thesis