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dc.contributor.authorManning, Cara C.  Concept link
dc.date.accessioned2016-12-13T19:33:35Z
dc.date.available2016-12-13T19:33:35Z
dc.date.issued2017-02
dc.identifier.urihttps://hdl.handle.net/1912/8589
dc.descriptionSubmitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2017en_US
dc.description.abstractIn this thesis, I use coastal measurements of dissolved O2 and inert gases to provide insight into the chemical, biological, and physical processes that impact the oceanic cycles of carbon and dissolved gases. Dissolved O2 concentration and triple isotopic composition trace net and gross biological productivity. The saturation states of inert gases trace physical processes, such as air-water gas exchange, temperature change, and mixing, that affect all gases. First, I developed a field-deployable system that measures Ne, Ar, Kr, and Xe gas ratios in water. It has precision and accuracy of 1 % or better, enables near-continuous measurements, and has much lower cost compared to existing laboratory-based methods. The system will increase the scientific community’s access to use dissolved noble gases as environmental tracers. Second, I measured O2 and five noble gases during a cruise in Monterey Bay, California. I developed a vertical model and found that accurately parameterizing bubble-mediated gas exchange was necessary to accurately simulate the He and Ne measurements. I present the first comparison of multiple gas tracer, incubation, and sediment trap-based productivity estimates in the coastal ocean. Net community production estimated from 15NO –3 uptake and O2/Ar gave equivalent results at steady state. Underway O2/Ar measurements revealed submesoscale variability that was not apparent from daily incubations. Third, I quantified productivity by O2 mass balance and air-water gas exchange by dual tracer (3He/SF6) release during ice melt in the Bras d’Or Lakes, a Canadian estuary. The gas transfer velocity at >90% ice cover was 6% of the rate for nearly ice-free conditions. Rates of volumetric gross primary production were similar when the estuary was completely ice-covered and ice-free, and the ecosystem was on average net autotrophic during ice melt and net heterotrophic following ice melt. I present a method for incorporating the isotopic composition of H2O into the O2 isotope-based productivity calculations, which increases the estimated gross primary production in this study by 46–97%. In summary, I describe a new noble gas analysis system and apply O2 and inert gas observations in new ways to study chemical, biological, and physical processes in coastal waters.en_US
dc.description.sponsorshipResearch and studies have been supported by funding from the National Science Foundation (NSF) through grants OCE-8608400 and PLR- 1304406 (to RHR Stanley) and OCE-1129644 (to DP Nicholson), the WHOI Arctic Research Initiative (funds to RHR Stanley and B Loose), a WHOI Innovative Technology grant (to RHR Stanley), the WHOI Coastal Ocean Institute (Student Research Fund to CC Manning), the WHOI Academic Programs Office (including an Ocean Ventures Fund grant to CC Manning), and the Houghton Fund at MIT. I received scholarships from the National Sciences and Engineering Research Council of Canada (NSERC) and the Canadian Meteorological and Oceanographic Society (CMOS).en_US
dc.language.isoen_USen_US
dc.publisherMassachusetts Institute of Technology and Woods Hole Oceanographic Institutionen_US
dc.relation.ispartofseriesWHOI Thesesen_US
dc.subjectGases
dc.subjectChemical oceanography
dc.titleInsight into chemical, biological, and physical processes in coastal waters from dissolved oxygen and inert gas tracersen_US
dc.typeThesisen_US
dc.identifier.doi10.1575/1912/8589
dc.subject.vesselWestern Flyer (Ship) Cruiseen_US  Concept link


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