Evidence of nitrate-based nighttime atmospheric nucleation driven by marine microorganisms in the South Pacific

Guillaume Chamba (1) , Matti Rissanen (2) , Theresa Barthelmeß , Alfonso Saiz-Lopez , Clémence Rose (1) , Siddharth Iyer (2) , Alexia Saint-Macary , Manon Rocco (1) , Karl Safi , Stacy Deppeler (3) , Neill Barr (3) , Mike Harvey (3) , Anja Engel (4) , Erin Dunne , Cliff S Law (3, 5) , Karine Sellegri (1)

1 LaMP - Laboratoire de Météorologie Physique
2 University of Tampere [Finland]
3 NIWA - National Institute of Water and Atmospheric Research [Wellington]
4 GEOMAR - Helmholtz Centre for Ocean Research [Kiel]
5 University of Otago [Dunedin, Nouvelle-Zélande]

Our understanding of ocean–cloud interactions and their effect on climate lacks insight into a key pathway: do biogenic marine emissions form new particles in the open ocean atmosphere? Using measurements collected in ship-borne air–sea interface tanks deployed in the Southwestern Pacific Ocean, we identified new particle formation (NPF) during nighttime that was related to plankton community composition. We show that nitrate ions are the only species for which abundance could support NPF rates in our semicontrolled experiments. Nitrate ions also prevailed in the natural pristine marine atmosphere and were elevated under higher sub-10 nm particle concentrations. We hypothesize that these nucleation events were fueled by complex, short-term biogeochemical cycling involving the microbial loop. These findings suggest a new perspective with a previously unidentified role of nitrate of marine biogeochemical origin in aerosol nucleation.

Mots clés: nucleation; marine atmosphere; marine aerosols; nitrate

Domaines: Océan, Atmosphère

Guillaume Chamba, Matti Rissanen, Theresa Barthelmeß, Alfonso Saiz-Lopez, Clémence Rose, et al.. Evidence of nitrate-based nighttime atmospheric nucleation driven by marine microorganisms in the South Pacific. Proceedings of the National Academy of Sciences of the United States of America, 2023, 120 (48), pp.e2308696120. ⟨10.1073/pnas.2308696120⟩. ⟨hal-04701058⟩