Nitrite Cycling in Warming Arctic and Subarctic Waters
Yangjun Chen, Min Chen
Abstract
Abstract The primary nitrite (NO 2 − ) maximum (PNM) is a typical feature of oceanic nitrogen (N) cycle, yet its characterization in the world ocean remains a gap. By combining the natural abundance of NO 2 − isotopes with geochemical model, we report for the first time that the formation of Arctic and subarctic PNMs is dominated by ammonia oxidation, while the oxidation of NO 2 − is the main sink. Notably, NO 2 − oxidation plays a more important role in Arctic and subarctic waters than in low‐ and mid‐latitude waters. The residence time of NO 2 − in the PNM further suggests that the NO 2 − cycle in the Arctic Ocean is more dynamic than in other marine ecosystems. Our findings provide insights into N cycle dynamics in the upper Arctic Ocean ecosystem.