A World Tour of Nitrite: Revealing the Ocean’s Invisible Chemistry

Nitrite is a fleeting but revealing chemical intermediate that traces the balance between microbial production and consumption of nitrogen within the ocean’s oxygen-deficient zones and the productive sunlit layer. Using newly reanalyzed UV-spectral data from the global Biogeochemical-Argo (BGC-Argo) float array, we can now observe nitrite - and maybe thiosulfate, an intermediate of the sulfur cycle that emerges when oxygen is absent - across vast regions and seasons, revealing signals previously invisible to scientists. This talk will take a world tour through these nitrite seascapes, from the Eastern Tropical Pacific to the Arabian Sea and the productive Equator, showing how nitrite dynamics expose microbial regime imbalances, the coupling between nitrogen and carbon cycles, and links to mesoscale physical features. I will conclude with perspectives on next-generation strategies and approaches that can extend this new chemical vision globally, offering a path toward real-time observation of the ocean’s invisible biogeochemical transformations.