Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), June 2011. / "June 2011." Cataloged from PDF version of thesis. / Includes bibliographical references. / Atmospheric nitrous oxide N₂O concentrations have been rising steadily for the past century as a result of human activities. In particular, human perturbation of the nitrogen cycle has increased the N₂O production rates of the two major sources of this greenhouse gas, soil and the ocean. Nitrification, and particularly ammonia oxidation, is one of the major processes that produces N₂O in the ocean. In this thesis, a series of stable isotopic methods have been used to characterize the biogeochemical controls on N₂O production by marine nitrification as well as the natural abundance stable isotopic signatures of N₂O produced by marine nitrifiers. This thesis shows that in addition to chemical controls on N₂O production rates such as oxygen (O₂) and nitrite (NO₂- ) concentrations, there are also biological controls such as nitrifier cell abundances and coastal phytoplankton blooms that may influence N₂O production by ammonia oxidizers as well. Ammonia oxidizers can produce N₂O through two separate biochemical mechanisms that have unique isotopic signatures. Using culture-based measurements of these signatures, we conclude that one of these pathways, nitrifier-denitrification, may be a significant source of N₂O produced in the South Atlantic Ocean and possibly the global ocean. / by Caitlin Frame. / Ph.D.
| Identifer | oai:union.ndltd.org:MIT/oai:dspace.mit.edu:1721.1/68887 |
| Date | January 2011 |
| Creators | Frame, Caitlin H |
| Contributors | Karen Casciotti., Woods Hole Oceanographic Institution., Joint Program in Oceanography/Applied Ocean Science and Engineering., Massachusetts Institute of Technology. Dept. of Earth, Atmospheric, and Planetary Sciences., Woods Hole Oceanographic Institution. |
| Publisher | Massachusetts Institute of Technology |
| Source Sets | M.I.T. Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 149 p., application/pdf |
| Rights | M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission., http://dspace.mit.edu/handle/1721.1/7582 |
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