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NET N2 FLUXES IN MUDDY SEDIMENTS OF GREAT PECONIC BAY: RATES, PATHWAYS & CONTROLS

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dc.contributor.advisor Aller, Robert C en_US
dc.contributor.author Waugh, Stuart en_US
dc.contributor.other Department of Marine and Atmospheric Science. en_US
dc.date.accessioned 2017-09-20T16:42:25Z
dc.date.available 2017-09-20T16:42:25Z
dc.date.issued 2015-12-01 en_US
dc.identifier.uri http://hdl.handle.net/11401/76125 en_US
dc.description 199 pg. en_US
dc.description.abstract Abstract of the Dissertation NET N2 FLUXES IN MUDDY SEDIMENTS OF GREAT PECONIC BAY: RATES, PATHWAYS & CONTROLS by Stuart Waugh Doctor of Philosophy in Marine and Atmospheric Sciences Stony Brook University 2015 Depending on its form, nitrogen (N) can exert a dominant control on marine productivity and ecosystem structure. Multiple geochemical processes are involved in redox transformations of nitrogen (N) in marine sediments. In coastal benthic environments, a number of abiotic and biological environmental factors control the extent to which these processes are relevant and therefore the outcomes of sedimentary N transformations. This dissertation seeks to quantify rates of net N remineralization in and fluxes from the un-vegetated, muddy sediments of Great Peconic Bay (GPB), NY and describe the relevance of the biogeochemical processes involved. Direct measurements of sediment – water solute fluxes (O2, N2, NH4+ & NO3-/NO2- ) were made both ex-situ and in-situ with benthic chambers; N & ΣCO2 remineralization was measured in anoxic incubations. Seasonal flux and remineralization patterns were investigated. Although GPB sediment produced net N2 (g) over each seasonal period measured, N2 fixation was found to have had a measureable impact on gross N2 fluxes especially when rates were low in spring periods. N2 production was influenced by temperature, reactive substrate availability, bio-irrigation (by Amphioplus abditus & Squilla empusa) and the presence of benthic algae. Estimates of sedimentary N remineralization were consistent with ΣCO2 production and approximated separately measured N fluxes (N2, NH4+ & NO3-/NO2-). 15N tracer experiments demonstrated denitrification was the dominant N2 production pathway and anammox contributed < 10% to net N2 production. There is evidence from previous studies denitrification is susceptible to environmental contaminants. This research investigated what impacts environmentally relevant concentrations of different classes of the commonly-used quaternary ammonium surfactant compounds (QACs) and Cu - alone and in combination- have on denitrification in GPB mud sediments. Highly adsorbent QACs were not found to impact N2 production in the fine-grained sediments of GPB but Cu was shown to often inhibit N2 production. Thus, increasing anthropogenic contaminant inputs could alter the benthic N cycle. To gain a preliminary understanding of how GPB sediments process modern-day N loadings into the GPB estuary, N2 flux estimates were compared with estimates of atmospheric and groundwater N inputs into the bay. These estimates show sedimentary N2 fluxes substantially reduce anthropogenic N loadings but do not eliminate them under some likely scenarios. en_US
dc.description.sponsorship This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree. en_US
dc.format Monograph en_US
dc.format.medium Electronic Resource en_US
dc.language.iso en_US en_US
dc.publisher The Graduate School, Stony Brook University: Stony Brook, NY. en_US
dc.subject.lcsh Chemical oceanography en_US
dc.title NET N2 FLUXES IN MUDDY SEDIMENTS OF GREAT PECONIC BAY: RATES, PATHWAYS & CONTROLS en_US
dc.type Dissertation en_US
dc.mimetype Application/PDF en_US
dc.contributor.committeemember Brownawell, Bruce en_US
dc.contributor.committeemember Cerrato, Robert en_US
dc.contributor.committeemember Mak, John en_US
dc.contributor.committeemember Giblin, Anne. en_US


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