Fluxes and sources of particulate organic carbon in the Ganga‐Brahmaputra river system

Sources and fluxes of particulate organic carbon (OC) in the Ganga‐Brahmaputra river system were estimated from 13 C/ 12 C ratios of bedrocks, soils, bank and suspended river sediments from a Himalayan watershed (Narayani, Nepal), and the Bangladesh floodplain. In the watershed of the Narayani, OC δ 13 C values for bank and suspended sediments have similar values and narrow ranges, with a mean of about −24.2‰ at the base of the Himalayas. On the Bangladesh floodplain, bank and suspended sediments are enriched in 13 C (δ 13 C about −22.5‰) relative to those collected at the base of the Himalayas. The OC exported at the base of the Himalayan range is estimated to include about 15% from the 13…