To understand how climate change impacts the global carbon cycle, we need a mechanistic understanding of natural processes driving the capture, storage and release of CO2 within landscapes. Photosynthesis removes carbon from the atmosphere, and the organic carbon (OC) stored in vegetation, soils, and sediments can be eroded and subsequently transported by rivers to marine depocenters. During transport, OC can be stabilized and temporally stored in floodplains or oxidized and returned to the atmosphere as CO2. The balance of storage and release controls the floodplains net carbon budget. Recent research suggests that OC storage can exceed the CO2 release on aggradational floodplains of meandering rivers over millennia. However, direct measurements of the CO2 release from fluvial systems are rare and it remains unclear how geomorphic features, such as channel type and associated floodplain morphology as well as seasonality affect CO2 release.

This data set comprises measurements of CO2 fluxes, CO2 d13C values and source d13C values along morphological gradients and two seasons. We measured CO2 fluxes and corresponding d13C values on the catchment-scale in the Rio Bermejo foreland, northwestern Argentina, using a static, non-stationary accumulation chamber. We measured fluxes from the water surface, from sediment deposited on recently exposed riverbeds, on the overbanks, and in paleochannels, along braided and meandering river reaches, during a wet and a dry season. Our aim was to understand how regional-scale morphology and seasonality impact the CO2 fluxes in a foreland floodplain.