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dc.contributor.advisorBenjamin A. S. Van Mooy.en_US
dc.contributor.authorCollins, James R. (James Robert)en_US
dc.contributor.otherWoods Hole Oceanographic Institution.en_US
dc.coverage.spatialt------ ln-----en_US
dc.date.accessioned2017-05-12T19:00:45Z
dc.date.available2017-05-12T19:00:45Z
dc.date.copyright2017en_US
dc.date.issued2017en_US
dc.identifier.urihttp://hdl.handle.net/1721.1/109053
dc.descriptionThesis: Ph. D., Joint Program in Oceanography (Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2017.en_US
dc.descriptionCataloged from PDF version of thesis.en_US
dc.descriptionIncludes bibliographical references.en_US
dc.description.abstractWhile aerobic respiration is typically invoked as the dominant mass-balance sink for organic matter in the upper ocean, many other biological and abiotic processes can degrade particulate and dissolved substrates on globally significant scales. The relative strengths of these other remineralization processes - including mechanical mechanisms such as dissolution and disaggregation of sinking particles, and abiotic processes such as photooxidation - remain poorly constrained. In this thesis, I examine the biogeochemical significance of various alternative pathways of organic matter remineralization using a combination of field experiments, modeling approaches, geochemical analyses, and a new, high-throughput lipidomics method for identification of lipid biomarkers. I first assess the relative importance of particle-attached microbial respiration compared to other processes that can degrade sinking marine particles. A hybrid methodological approach - comparison of substrate-specific respiration rates from across the North Atlantic basin with Monte Carlo-style sensitivity analyses of a simple mechanistic model - suggested sinking particle material was transferred to the water column by various biological and mechanical processes nearly 3.5 times as fast as it was directly respired, questioning the conventional assumption that direct respiration dominates remineralization. I next present and demonstrate a new lipidomics method and open-source software package for discovery and identification of molecular biomarkers for organic matter degradation in large, high-mass-accuracy HPLC-ESI-MS datasets. I use the software to unambiguously identify more than 1,100 unique lipids, oxidized lipids, and oxylipins in data from cultures of the marine diatom Phaeodactylum tricornutum that were subjected to oxidative stress. Finally, I present the results of photooxidation experiments conducted with liposomes - nonliving aggregations of lipids - in natural waters of the Southern Ocean. A broadband polychromatic apparent quantum yield (AQY) is applied to estimate rates of lipid photooxidation in surface waters of the West Antarctic Peninsula, which receive seasonally elevated doses of ultraviolet radiation as a consequence of anthropogenic ozone depletion in the stratosphere. The mean daily rate of lipid photooxidation (50 ± 11 pmol IP-DAG L⁻¹ d⁻¹, equivalent to 31 ± 7 [mu]g C m⁻³ d⁻¹) represented between 2 and 8 % of the total bacterial production observed in surface waters immediately following the retreat of the sea ice.en_US
dc.description.statementofresponsibilityby James R. Collins.en_US
dc.format.extent300 pagesen_US
dc.language.isoengen_US
dc.publisherMassachusetts Institute of Technologyen_US
dc.rightsMIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission.en_US
dc.rights.urihttp://dspace.mit.edu/handle/1721.1/7582en_US
dc.subjectJoint Program in Oceanography.en_US
dc.subjectEarth, Atmospheric, and Planetary Sciences.en_US
dc.subjectWoods Hole Oceanographic Institution.en_US
dc.subject.lcshMicroorganismsen_US
dc.subject.lcshRespirationen_US
dc.subject.lcshLiposomesen_US
dc.titleThe remineralization of marine organic matter by diverse biological and abiotic processesen_US
dc.typeThesisen_US
dc.description.degreePh. D.en_US
dc.contributor.departmentJoint Program in Oceanographyen_US
dc.contributor.departmentWoods Hole Oceanographic Institutionen_US
dc.contributor.departmentMassachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
dc.identifier.oclc986241065en_US


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