Funds are provided for the PIs to carry out a multi-faceted, multi-disciplinary research towards understanding sediment and organic matter fluxes in the Fly River, Papua New Guinea. The work builds on previous study by the PIs working in the lower reaches of the Fly River River to understand sediment delivery and dispersal, and in the Fly delta and offshore clinoform to understand organic matter burial in the system. The work will test three related hypotheses, all important as the stated goals of the MARGINS' source-to-sink initiative: 1) that the Fly River transports, buries and sequesters a globally significant amount of organic carbon; 1) sediment exchange processes between channels and floodplains modulate biogeochemical fluxes, and 3) partial and full channel avulsions govern sediment and carbon accumulation across the distal floodplain. Field surveys and sampling and coring of the floodplains is planned, as are lab studies and modeling efforts at three different institutions.