Tracking the export of terrestrial carbon to tropical streams and rivers
Map Library, Rm10.10, 10/F, The Jockey Club Tower, Centennial Campus, HKU
Dr Clément Duvert Research Associate, Charles Darwin University, Australia
About the Speaker:
Clément Duvert is a Research Associate at Charles Darwin University (Australia). Clem’s research interests include understanding the movement of water and carbon through the landscape. He uses isotopic techniques to evaluate the residence time of water and associated solutes in catchments and to delineate flow pathways. His current research at Charles Darwin University aims at quantifying the transport of inorganic and organic carbon from tropical savanna soils to aquifers and rivers.
There is now consensus that tropical streams and rivers contribute disproportionately to the global export of terrestrial carbon. However, observations are still lacking in the tropics, and this hinders the development of more reliable carbon budgets both at local and global scales. In this presentation I will provide an overview of the work we have been conducting in southeast Asia (Laos) and northern Australia. I will first outline the role of groundwater in transporting massive amounts of dissolved carbon to streams and rivers, where it is then processed or degassed as CO2. The localised nature of groundwater inflows makes this flux particularly challenging to measure. I will also show the importance of assessing the source(s) of dissolved inorganic carbon in rivers, since a substantial proportion of this flux may have a weathering origin, hence should not be counted as a “loss” of terrestrial carbon. Lastly, I will discuss the whole-carbon budget of a lowland savanna catchment obtained by combining eddy-covariance flux tower measurements and river monitoring. I will compare the relative effects of fire emissions and aquatic carbon export on the terrestrial carbon storage of this ecosystem.
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