Does diel biogeochemical cycling in the surface ocean influences cloud formation?

durch Theresa Barthelmeß (BI/MB)

Donnerstag 06.03.2025, 10:00 → 11:30 Europe/Berlin

8A-002 - Hörsaal Ostufer / Lecture Hall East (GEOMAR - Standort Ostufer / GEOMAR - East Shore)

It is well known that the diel light cycle in the surface ocean influences phytoplankton production as well as associated bacterial degradation. However, the diel release of fresh and dissolved organic material remains largely unexplored. During our Sea2Cloud voyage in the Southern Pacific Ocean we found that a relevant amount of total organic carbon (TOC) is released and cycled during the day. Dissolved combined carbohydrates (DCCHO) but also dissolved amino acids (DAA) contributed to this diel turnover and decoupled times of highest concentration in surface waters suggested divergent source dynamics. The diel turnover has implications for ecosystem services as it impacts nutrient cycling and the microbial carbon pump. Tentatively, we found evidence that this so far unnoticed diel cycling of fresh and dissolved products may even influence climate dynamics. Secondary aerosols are important components initiating cloud formation above the Southern hemisphere oceans. Our ambient and in-situ atmospheric measurements during the Sea2Cloud expedition revealed night-time secondary aerosol mass formation, which was based on nitrogen-containing precursor species and synchronized with the peak and successive fate of DAA concentration. Environmental stressors, such as viral lysis, may trigger cellular pathways of damage control by producing relevant aerosol precursor species. During the FB2 seminar, we will explore potential microbial links between small-scale biogeochemical cycling in the surface ocean and the observed aerosol formation.