Conference presentation
Drivers of dissolved CO2 and CH4 dynamics in artificial drains of a coastal floodplain following a flood.
V. M. Goldschmidt Conference, 26th (Yokohama, Japan, 26/06/2016 - 01/07/2016)
28/06/2016
Metrics
30 Record Views
Abstract
Many coastal floodplains have been artificially drained for agriculture, altering hydrological connectivity and the delivery of groundwater-derived solutes including CO2 and CH4 to surface waters. Here, we investigated the drivers of CO2 and CH4 within the artificial drains of a coastal floodplain under sugarcane plantation, and quantify the relative contribution of groundwater to CO2 and CH4 fluxes over a flood. High temporal resolution, in situ observations of dissolved CO2 and CH4, stable isotope (δ13C-CH4), and a natural groundwater tracer radon allowed us to quantify CO2, CH4 and groundwater dynamics during the rapid recession of a flood over five days. Extreme super-saturation of CO2 (25,480%) was driven largely by mass groundwater input into the drains, facilitated by the creation of a large hydraulic head between the surface water and groundwater. Groundwater input sustained the CO2 flux by delivering high carbonate alkalinity groundwater to acidic surface water, consequently transforming all groundwater-derived DIC to CO2. In contrast to CO2, groundwater was not a major driver of CH4 fluxes. Instead, the flood appeared to indirectly enhance CH4 fluxes through the delivery of organic matter substrates to the drain sediments. This resulted in large diurnal oscillations in CH4 concentrations (101,690%) driven by production and oxidation at the sediment-water interface. Our findings demonstrate how separate processes can drive the CO2 and CH4 response to a flood event in a drained coastal floodplain, and the key role groundwater has in post flood CO2 fluxes.
Details
- Title
- Drivers of dissolved CO2 and CH4 dynamics in artificial drains of a coastal floodplain following a flood.
- Creators
- Jackie R Webb - Southern Cross UniversityIsaac R Santos - Southern Cross UniversityDouglas R Tait - Southern Cross UniversityJames Sippo - Southern Cross UniversityBen McDonaldBarbara RobsonDamien T Maher - Southern Cross University
- Conference
- V. M. Goldschmidt Conference, 26th (Yokohama, Japan, 26/06/2016 - 01/07/2016)
- Identifiers
- 991012845996902368
- Academic Unit
- Faculty of Science and Engineering; National Marine Science Centre; School of Environment, Science and Engineering; Science
- Resource Type
- Conference presentation