Spatial and temporal variability in methane and carbon dioxide exchange at three coastal marshes along a salinity gradient in a northern Gulf of Mexico estuary

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dc.contributor Kiene, Ronald P.
dc.contributor Starr, Gregory
dc.contributor.advisor Mortazavi, Behzad
dc.contributor.author Wilson, Benjamin
dc.date.accessioned 2017-03-01T16:50:58Z
dc.date.available 2017-03-01T16:50:58Z
dc.date.issued 2013
dc.identifier.other u0015_0000001_0001367
dc.identifier.other Wilson_alatus_0004M_11656
dc.identifier.uri https://ir.ua.edu/handle/123456789/1834
dc.description Electronic Thesis or Dissertation
dc.description.abstract Carbon fluxes in tidal marshes vary spatially and temporally because of vegetation cover, subsurface biogeochemical processes, and environmental forcing. The objective of this study was to examine how ecosystem carbon exchange changes along an estuarine salinity gradient. I measured greenhouse gas fluxes, methane (CH_4) and carbon dioxide (CO_2), from three marshes along a salinity gradient (0-32 ppt) in the Mobile Bay estuary, Alabama, USA. CH_4 flux ranged from 1.2 to 2.4 mmol CH_4 m^-2 d^-1 with no significant differences across sites. Soil temperature, dissolved inorganic nitrate and nitrite, and ecosystem respiration of CO_2, not salinity, were correlated to CH_4 emissions. Midday net ecosystem exchange was greatest at the most fresh site (-4.8 ± 0.3 μmol CO_2 m^-2 s^-1), followed by the saline (-2.8 ± 1.0 μmol CO_2 m^-2 s^-1) and brackish (-1.4 ± 0.6 μmol CO_2 m^-2 s^-1) sites. However, net ecosystem exchange integrated over a diurnal time period using a shade cloth technique revealed each marsh to be a net CO_2 source to the atmosphere as a result of high ecosystem respiration with no difference across the fresh (105.5 ± 28.9 mmol CO_2 m^-2 d^-1), brackish (100.1 ± 36.5 mmol CO_2 m^-2 d^-1), and salt marsh (78.3 ± 28.6 mmol CO_2 m^-2 d^-1) sites. These findings lead to the conclusion that either the marshes are losing carbon or that they receive a subsidy of respirable carbon, possibly via tidal deposition. The extent to which sedimentation from tidal deposition contributes carbon to these ecosystems, however, remains unknown. Without such a subsidy, marshes in the study area will not be able to keep up with sea level rise.
dc.format.extent 93 p.
dc.format.medium electronic
dc.format.mimetype application/pdf
dc.language English
dc.language.iso en_US
dc.publisher University of Alabama Libraries
dc.relation.ispartof The University of Alabama Electronic Theses and Dissertations
dc.relation.ispartof The University of Alabama Libraries Digital Collections
dc.relation.hasversion born digital
dc.rights All rights reserved by the author unless otherwise indicated.
dc.subject.other Biogeochemistry
dc.subject.other Ecology
dc.subject.other Plant biology
dc.title Spatial and temporal variability in methane and carbon dioxide exchange at three coastal marshes along a salinity gradient in a northern Gulf of Mexico estuary
dc.type thesis
dc.type text
etdms.degree.department University of Alabama. Dept. of Biological Sciences
etdms.degree.discipline Biological Sciences
etdms.degree.grantor The University of Alabama
etdms.degree.level master's
etdms.degree.name M.M.S.


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