Conference presentation
Drivers of high pCO2 and CH4 concentrations and evasion rates in mangrove dominated estuaries.
ASLO Aquatic Sciences Meeting (Honolulu, USA, 26/02/2017 - 03/03/2017)
02/03/2017
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Abstract
Mangrove estuaries are in the dynamic interface between rivers and the ocean and play an important role in coastal carbon budgets. However, greenhouse gas sources and sinks in mangroves are not well quantified due to high spatial and temporal variability and limited data availability. This study compares two pristine and one anthropogenically impacted mangrove system in tropical north Queensland, Australia. pCO2 and CH4 concentrations and carbon stable isotopic composition were measured over two tidal cycles in the wet and dry season using Cavity-Ring-Down Spectroscopy. Overall, we found a large range of pCO2 (387 to 13,031 µatm), CH4 (6 to 1,069 nM), δ13C-CO2 (-8.78 to -21.68 ‰) and δ13C-CH4 (-22.54 to -67.35 ‰) between the mangrove systems and between low and high tides due to differences in porewater exchange, riverine inputs of terrestrial carbon, and in situ biological processes. The impacted mangrove system showed on average higher CH4 concentrations compared to the pristine mangroves, although we observed high concentrations of CH4 at low tide during the wet season in one of the pristine mangrove creeks. We further discuss CO2 and CH4 water to atmosphere fluxes and related uncertainties with using gas transfer velocities (k) from different empirical models. Average estuary wide evasion rates of CO2 (53 to 455 mmol m-2 d-1) and CH4 (0.09 to 0.85 mmol m-2 d-1) were at the high end compared to previous measurements in mangrove waters. The particularly high CH4 flux rates suggest that mangrove waters may be a stronger atmospheric CH4 source to the atmosphere than previously thought.
Details
- Title
- Drivers of high pCO2 and CH4 concentrations and evasion rates in mangrove dominated estuaries.
- Creators
- Judith A Rosentreter - Southern Cross UniversityDamien T Maher - Southern Cross UniversityRachel H Murray - Southern Cross UniversityDirk Erler - Southern Cross UniversityBradley D Eyre - Southern Cross University
- Conference
- ASLO Aquatic Sciences Meeting (Honolulu, USA, 26/02/2017 - 03/03/2017)
- Identifiers
- 991012845997502368
- Academic Unit
- Faculty of Science and Engineering; Centre for Coastal Biogeochemistry; School of Environment, Science and Engineering; Science
- Resource Type
- Conference presentation