资源环境科技发展态势分析平台

Identifying drivers of seasonal variations in fluvial particulate organic carbon (POC) composition can aid sediment provenance and biogeochemical cycling studies. We evaluate seasonal changes in POC composition in the Río Bermejo, Argentina, a lowland river running ∼1270 km without tributaries. Weekly POC concentration and isotopic composition from 2016-2018 show that during the wet season, increased lateral channel migration generates an influx of ¹³C- and ¹⁴C-enriched floodplain-sourced material, overprinting the ¹³C- and ¹⁴C-depleted headwater-signature that is observed during the dry season. These findings demonstrate how channel morphodynamics can drive variability of POC composition in lowland rivers, and may modulate the composition of POC preserved in sedimentary archives.