Fluvial Organic Carbon Composition Regulated by Seasonal Variability in Lowland River Migration and Water Discharge

Identifying drivers of seasonal variations in fluvial particulate organic carbon (POC) composition can aid sediment provenance and biogeochemical cycling studies. We evaluate changes POC the Río Bermejo, Argentina, a lowland river running ?1,270 km without tributaries. Weekly concentration isotopic from 2016 to 2018 show that during wet season, increased lateral channel migration generates an influx 13C-enriched 14C-enriched floodplain-sourced material, overprinting 13C-depleted 14C-depleted headwater signature is observed dry season. These findings demonstrate how morphodynamics drive variability rivers, may modulate preserved sedimentary archives.