Conference presentation
Mangrove porewater exchange across a latitudinal gradient
V. M. Goldschmidt Conference, 26th (Yokohama, Japan, 26/06/2016 - 01/07/2016)
30/06/2016
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Abstract
We combined observations of the natural tracers radon (222Rn) and radium (223Ra, 224Ra and 226Ra) with hydrodynamic models across a broad latitudinal gradient to estimate porewater exchange rates in mangroves. Porewater exchange ranged from 2.1 to 35.5 cm day-1 from temperate to tropical regions. Using the different tracers 222Rn, 223Ra and 224Ra, the calculated mass balance porewater exchange rates over the entire gradient averaged 16.8 ± 5.1, 11.4 ± 4.4, and 14.1 ± 4.7 cm tidalcycle-1, respectively. We hypothesize that the difference in porewater exchange estimates is potentially due to the overestimation of wind and current evasion rates when the 222Rn mass balance model is applied to mangroves and the longer decay rate of 224Ra. Analysis of sediment permeability characteristics indicated that the difference in porewater exchange rates can be attributed to crab burrow number and morphology. If upscaled to global weighted mangrove area, porewater exchange in mangroves would recirculate the entire volume of water overlying the continental shelf in 157 to 260 years using 222Rn and 224 Ra respectively, and is equivalent to between 20% and 33% of global annual river discharge to the oceans. Because biogeochemical processes in mangroves are largely dependent on porewater exchange, these large exchange rates have major implications for coastal nutrient, carbon, and greenhouse gas cycling in tropical marine systems.
Details
- Title
- Mangrove porewater exchange across a latitudinal gradient
- Creators
- Douglas R Tait - Southern Cross UniversityDamien T Maher - Southern Cross UniversityPaul A Macklin - Southern Cross UniversityIsaac R Santos - Southern Cross University
- Conference
- V. M. Goldschmidt Conference, 26th (Yokohama, Japan, 26/06/2016 - 01/07/2016)
- Identifiers
- 991012845997102368
- Academic Unit
- Faculty of Science and Engineering; National Marine Science Centre; School of Environment, Science and Engineering; Science
- Resource Type
- Conference presentation