Bulk carbon and lignin fingerprinting of catchment sediments transported by mountain rivers in Nepal Himalayas

The Himalayan rivers yield the most significant flux of continental sediments into ocean. Organic matter (OM) transported by these provides a peek at influence diverse geological terrains, soil types, vegetation, and climate on carbon cycling within narrow boundary. We analyzed suspended bedload from four to trace their sources, elucidate fate during fluvial transport, estimate organic (OC) flux. Hence, total OC (TOC), dissolved (DOC), C:N ratios, lignin phenols were measured. Consistent with erosional intensity in rivers, sediment load input followed order: Kaligandaki > Myagdikhola Aadhikhola Tinahukhola. values Lesser Himalayas Siwalik indicate mixed biogenic sources. In contrast, high TOC C/N trans-Himalaya flowing through barren landscapes reflect erosion catchment yielding petrogenic carbon. has higher phenol concentrations than Higher Himalaya rivers. ratios degradation trans sections. This implies that only small fraction terrestrial OM deposits ocean sink. Siwaliks sequester amount bound bedload. As result, transferred lower particulate (POC) but DOC similar worldwide. Rivers transfer 90 % annual POC monsoons. Finally, although transport less other global traversing densely vegetated landscapes, sheer number implications catchments sediments.