The Xiamen Symposium on Marine Environmental Sciences (XMAS 2025)

The biological carbon pump plays a pivotal role in the global carbon cycle by transporting organic carbon from the euphotic zone to the deep ocean. This process aids in lowering atmospheric [CO₂], it is critical in mitigating the impacts of global climate change. Our study tracks the production, export, and remineralization of particulate organic carbon (POC) mediated by phytoplankton, zooplankton, and bacteria in oceanic ecosystems, focusing on the seasonal and regional dynamics of organic particles across the global ocean. Using BGC-Argo float data, we identified key, but understudied, mechanisms regulating vertical POC flux, including plankton vertical migration and particle fragmentation. Here, we provide three case studies to highlight new discoveries by BGC-Argo: 1. POC dynamics in the Sargasso Sea, a typical nutrient-poor oligotrophic ocean, 2. the characteristics of mesopelagic carbon plumes in the global ocean, and 3. machine learning advancements in modeling biogeochemical parameters related to the biological carbon pump. Our findings provide observational insights into the high spatiotemporal variability and efficiency of the biological pump, with potential implications for closing the global carbon budget in ecological models and informing marine carbon dioxide removal (mCDR) strategies.

BGC-Argo, ocean observation, biological carbon pump, biogeochemical model