Poster

IAPSO

JPM04 - Indian Ocean Sciences

Spatial Distribution and Isotopic Signatures of Dissolved and Particulate Organic Carbon in the Western Indian Ocean

The distribution of dissolved and particulate organic carbon (DOC and POC) in marine environments plays a critical role in understanding the ocean's capacity to store and absorb atmospheric CO2. DOC represents the largest ocean carbon reservoir influencing long-term carbon storage. POC, produced by primary producers capturing atmospheric CO2 in the surface ocean, is a crucial component of the biological carbon pump and is closely linked to carbon fluxes in the water column. The tropical western Indian Ocean is a region that contains the Seychelles-Chagos Thermocline Ridge (SCTR), an open-ocean upwelling zone with relatively high productivity, and plays a crucial role in understanding the regional and global biogeochemical cycles and carbon cycle. Despite its significance, research on DOC and POC in the western Indian Ocean remains limited. In this study, we analyzed the concentration and stable carbon isotopes of DOC and POC in the western Indian Ocean in 2023 to determine the spatial distribution of organic carbon concentration and its sources. DOC and POC concentrations ranged from 851.2 to 1062.5 ug/L and 12.8 to 57.8 ug/L, respectively, showing relatively higher concentrations within the SCTR region. Stable carbon isotope of DOC and POC ranged from -25.2 to -22.2�� and -20.0 to -25.0��. This distribution suggests that organic carbon distribution and their sources were influenced by oceanic physical circulation and associated variations in productivity.