Work

Stability of the marine nitrogen cycle over the past 165 million years

Year: 2025

Type: article

Abstract: Nitrogen and phosphorus are the two macro-nutrients that limit biological productivity in the ocean. While the supply of P depends on geological processes, N is biologically supplied from an inexhaustible atmospheric source, but can be limited by micro-nutrients, especially iron. Here we present a record of N and C isotopes over the past 165 Ma in marine sediments to address feedbacks between the N-cycle and productivity. Over most of the last 165 Myr, the fixed N averaged +3.2‰, (−2 and +9‰), but higher in distal areas of the ocean due to limited vertical mixing. Using an isotope box model and a coupled climate model we show that this is caused by winds that induce upwelling changing due to continental meander. Upwelling along low latitude east-west orientated Tethyan coastlines results in low δ 15 N, while upwelling along narrow N-S coastlines as it does today, results in high δ 15 N due to denitrification.

Source: Nature Communications

DOI: 10.1038/s41467-025-63604-x

Authors: Linda V. Godfrey, Anne Willem Omta, Eli Tziperman, Xiang Li, Yongyun Hu, Paul G. Falkowski

Institutions: Rutgers, The State University of New Jersey, Case Western Reserve University, Harvard University, Peking University

Language: English

Topic: Paleontology and Stratigraphy of Fossils

Subfield: Paleontology

Field: Earth and Planetary Sciences

Domain: Physical Sciences

SDGs: Life below water, Climate action

Open Access status: gold

Estimated APC paid: $6,990