Stable isotope measurements from a cold polar desert and marine oxygen deficient zone reveal clues about the global nitrogen cycle
Abstract/Contents
- Abstract
- The global nitrogen (N) cycle is closely linked to the carbon cycle. Accordingly, it has been proposed that changes in the N cycle could have played a role in climatic shifts on glacial-interglacial timescales, although these feedbacks are still not well understood. Modern natural and anthropogenic forcings are currently pushing the N cycle out of balance, it is therefore increasingly important to obtain a better understanding of the processes that comprise the modern N cycle. One pressing question surrounding the global N cycle is the source(s) of N2O, a known greenhouse gas. While most N2O is thought to be produced biologically, some studies have presented evidence for abiotic sources, which could alter our current understanding of N2O fluxes to the atmosphere. I present stable isotope measurements of NO2-, NO3-, NH4+, and N2O from the McMurdo Dry Valleys, Antarctica, in an attempt to constrain possible sources of N2O in cold, arid environments. Another problem in the global N cycle concerns the imbalance between sources and sinks of N in the marine environment. Specifically, previous studies have suggested that bioavailable forms of N are being removed faster than they are being supplied, which could thus reduce the ability of marine phytoplankton to take up CO2 from the atmosphere. Much of this N removal occurs in marine oxygen deficient zones (ODZs), where anaerobic bacteria and archaea convert bioavailable NO3- and NO2- to N2, a form of N that cannot be utilized by most organisms. However, recent studies have provided strong evidence for internal recycling between NO3- and NO2- in ODZs, which results in no bioavailable N removal. In order to explore these and other questions surrounding the marine N cycle, I present stable isotope measurements of NO2-, NO3-, and N2 from the ODZ in the eastern tropical south Pacific, which are used to examine the fate of bioavailable N in the marine environment. I also the consider the importance water masses in driving stable isotope distributions. Together these findings suggest that 1) a substantial fraction of bioavailable N is indeed recycled rather removed, which may render current estimates of fixed N removal too high, and 2) physical processes can efficiently transport locally generated isotopic signals across the greater Pacific basin, and thus need to be taken in to account. My hope is that these results enhance our understanding of the global N cycle, and, in turn, yield some additional clues into potential feedbacks with the larger earth system.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2016 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Peters, Brian |
|---|---|
| Associated with | Stanford University, Department of Environmental Earth System Science. |
| Primary advisor | Casciotti, Karen Lynn, 1974- |
| Thesis advisor | Casciotti, Karen Lynn, 1974- |
| Thesis advisor | Arrigo, Kevin R |
| Thesis advisor | Thomas, Leif N |
| Advisor | Arrigo, Kevin R |
| Advisor | Thomas, Leif N |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Brian Peters. |
|---|---|
| Note | Submitted to the Department of Environmental Earth System Science. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2016. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2016 by Brian David Peters
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
Also listed in
Loading usage metrics...