Oceanic islands in the western Pacific export ∼35% of particulate organic carbon (OC) to the world ocean, but composition and age of OC varies dramatically among and within the islands. Understanding island-wide variation in sources and controls on the sedimentary OC in a series of rivers is therefore essential to assess the role of oceanic islands on the global carbon cycle. Stable and radioactive carbon isotopic compositions of sedimentary OC in 17 rivers across Taiwan indicate various proportions of biospheric OC derived from soil overlain by C3 and C4 vegetation and petrogenic OC from sedimentary and metamorphic rocks. Higher fractions of biospheric OC occur in sediments of northwestern rivers, while petrogenic OC is dominant in southern river sediments. Vegetation type, lithological setting, and sediment yield in river basins largely control island-wide OC compositions in river sediments. Considerable differences in export fluxes of biospheric and petrogenic OC based on different provenance proxies exist for individual rivers, highlighting the need for additional radiocarbon measurement (with high sample frequency) to better understand the role of oceanic islands in the global carbon cycle.
All Science Journal Classification (ASJC) codes
- Geochemistry and Petrology
- Earth and Planetary Sciences (miscellaneous)
- Space and Planetary Science