Work

Long-term nitrogen burial exceeds denitrification in global fjords

Year: 2026

Type: article

Abstract: Nitrogen (N) availability regulates primary productivity and hence directly affects global oceanic carbon sequestration. Global fjords account for up to 11% of marine carbon burial. However, N loss via sediment burial remains largely unquantified. Here, we show that global fjords are hotspots of N burial, accounting for up to 18% of oceanic N burial despite only covering 0.1% of the ocean area. Burial is the dominant N loss mechanism, exceeding microbial N loss via denitrification and anammox, which are generally considered the major N loss mechanisms. Microbial N loss dominates in anoxic fjords and appears to be a function of temperature and nutrient availability. Overall, fjords efficiently sequester excess N in sediments over long time scales. Accelerated warming will promote both N burial from increased primary production and microbial N loss from warmer temperatures, affecting N budgets in fjords and in the ocean in general.

Source: Nature Communications

DOI: 10.1038/s41467-026-71116-5