SEASONAL CHANGES IN HYDROLOGY DRIVE LARGE, RAPID FLUXES OF CO2 FROM STREAMS IN WET-DRY TROPICS

Warm temperatures and high terrestrial productivity cause tropical streams to be hotspots for greenhouse gas (GHG) cycling. The wet-dry tropics of Australia display intense seasonal variability of precipitation with potentially high influence on stream GHG exports. However, our understanding of seasonal GHG dynamics in tropical streams is limited by scarce time series data, particularly in headwater streams. To better understand the magnitude and fate of GHG exports from streams in highly seasonal tropical climates, we used a combination of time series data and spatial sampling to quantify the exports of CO₂ downstream and to the atmosphere at a daily timescale. Additionally, we explore the main drives for CO₂ export. We find that export of CO₂ is largely transport–rather than source–limited, with the majority  of CO₂ export occurring during the three wettest months of the year. Additionally, a majority of CO₂ that enters the system is emitted to the atmosphere, rather than transported downstream. This work highlights the need to account for the observed temporal variability of GHG exports in tropical systems, which in turn require sampling designs that can capture these dynamics.  

Presentation Preference: Oral

Primary Presenter: Adam Rexroade, Charles Darwin University (rexroadea@gmail.com)

Authors:

Marcus Wallin, Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences  (marcus.wallin@slu.se)

Francesco Ulloa-Cedamanos, Research Institute for Environment and Livelihoods, Charels Darwin University  (francesco.ulloacedamanos@cdu.edu.au)

Clément Duvert, Research Institute for Environment and Livelihoods, Charels Darwin University  (clem.duvert@cdu.edu.au)