Spatial and temporal heterogeneity of methane and carbon dioxide production and flux in a temperate tidal salt marsh
| Author(s) | Bothfeld, Frances | |
| Date Accessioned | 2016-05-20T12:53:11Z | |
| Date Available | 2016-05-20T12:53:11Z | |
| Publication Date | 2016 | |
| Abstract | Salt marshes naturally contribute CO2 and CH4 greenhouse gas fluxes to the atmosphere. These fluxes are governed by biogeochemical processes in sediments that are sensitive to local conditions (e.g., temperature, water table fluctuations), which can result in spatial heterogeneity of production and flux in an ecosystem. Therefore, it is critical to understand the driving forces behind CO2 and CH4 production and consumption in order to produce accurate estimates of CH4 and CO2 contributions to the atmosphere from salt marshes and to understand how it might change with the advent of environmental stressors. In this study, we evaluated the temporal and spatial heterogeneity of biogeochemical cycling of redox-sensitive parameters and CO2 and CH4 production and flux in a tidal salt marsh. Two subsites within the marsh with different hydrological regimes were monitored over a one-year period for changes in CO2 and CH4 flux to the atmosphere and pore-water chemistry at discrete depths to 90 cm. Additionally, we more intensely monitored CO 2 and CH4 production with depth and hydrological dynamics at these subsites over one summer month. We found that the subsite proximal to the tidal channel (“near channel subsite”) had larger water table elevation fluctuations that resulted in variable, but relatively high, redox values and led to higher CO2 and typically lower CH 4 fluxes compared to the subsite farther from the tidal channel (“interior subsite”), which experienced a higher water table elevation, more inundation, lower redox values, and lower CO2 fluxes. The spatial heterogeneity of inundation due to hydrologic factors likely led to differences in dominant soil respiration processes at the two subsites (e.g., aerobic respiration vs. Fe(III) reduction vs. SO42- reduction), which affects the production and flux of CO2 and CH4 to the atmosphere. Moreover, the production of these gases with depth revealed a large pool of stored CO2 and CH4 gases that has the potential to efflux during land-use change. The interplay of hydrology and sediment biogeochemistry and their effect on spatial heterogeneity in a salt marsh should be considered when attempting to understand the current levels and future dynamics of CO2 and CH4 fluxes from salt marshes. | en_US |
| Advisor | Seyfferth, Angelia | |
| Degree | M.S. | |
| Program | University of Delaware, Program in Water Science and Policy | |
| Unique Identifier | 950004877 | |
| URL | http://udspace.udel.edu/handle/19716/17733 | |
| Publisher | University of Delaware | en_US |
| URI | http://search.proquest.com/docview/1776481154?accountid=10457 | |
| dc.subject.lcsh | Salt marshes -- Delaware. | |
| dc.subject.lcsh | Methane -- Delaware. | |
| dc.subject.lcsh | Carbon dioxide -- Delaware. | |
| Title | Spatial and temporal heterogeneity of methane and carbon dioxide production and flux in a temperate tidal salt marsh | en_US |
| Type | Thesis | en_US |