Nonpyrogenic "Black" Nitrogen Likely Plays a Major Yet Underrecognized Role in the Global Nitrogen Cycle

Authors

• João Vitor dos Santos, Old Dominion UniversityFollow
• Aleksandar I. Goranov, Old Dominion UniversityFollow
• Kyle M. Lambert, Old Dominion UniversityFollow
• Theodoro da Rosa Salles, State University of Campinas, Brazil
• Susan J. Carter, Harvard University
• Ann Pearson, Harvard University
• Patrick G. Hatcher, Old Dominion UniversityFollow

Document Type

Article

Publication Date

2026

DOI

10.1021/acs.est.5c15974

Publication Title

Environmental Science & Technology

Volume

60

Issue

15

Pages

11486-11499

Abstract

Condensed aromatic nitrogen (ConAN) is commonly found in soil and aquatic environments. ConAN is broadly viewed by the biogeochemistry community as a combustion-derived product leading to its frequent designation as pyrogenic “black” nitrogen. Here, we provide evidence that ConAN can also form through nonpyrogenic pathways. In an experiment simulating biomass oxidation, pine wood boards assembled with iron nails were exposed to 12 years of natural environmental conditions. Nitrogen concentrations increased from 0.2 to 1.2 wt % with increasing proximity to the nail. Ultrahigh resolution mass spectrometry showed enrichment of nitrogen-containing compounds within the lignin and condensed aromatic domains. X-ray spectroscopic characterization revealed the development of C–N bonds and formation of pyridinic and pyrrolic nitrogen moieties. We propose plausible nonpyrogenic formation mechanisms for ConAN and perform back-of-the-envelope calculations suggesting that biomass oxidation yields a nonpyrogenic ConAN flux to soils of 3–63 Tg-N yr^–¹. These findings demonstrate that ConAN can form under fire-free environmental conditions, highlighting nonpyrogenic ConAN as an underrecognized but potentially major component of the global nitrogen cycle. More broadly, this study reveals a previously ignored pathway for the long-term incorporation of nitrogen into refractory “stable” organic matter in soils and other environments.

Rights

© 2026 The Authors.

This publication is licensed under a Creative Commons Attribution 4.0 International (CC BY 4.0) License.

Original Publication Citation

Dos Santos, J. V., Goranov, A. I., Lambert, K. M., da Rosa Salles, T., Carter, S. J., Pearson, A., & Hatcher, P. G. (2026). Nonpyrogenic "black" nitrogen likely plays a major yet underrecognized role in the global nitrogen cycle. Environmental Science & Technology, 60(15), 11486-11499. https://doi.org/10.1021/acs.est.5c15974

ORCID

0000-0002-5103-0838 (Goranov), 0000-0002-8230-2840 (Lambert)

Repository Citation

Vitor dos Santos, João; Goranov, Aleksandar I.; Lambert, Kyle M.; Rosa Salles, Theodoro da; Carter, Susan J.; Pearson, Ann; and Hatcher, Patrick G., "Nonpyrogenic "Black" Nitrogen Likely Plays a Major Yet Underrecognized Role in the Global Nitrogen Cycle" (2026). Chemistry & Biochemistry Faculty Publications. 390.
https://digitalcommons.odu.edu/chemistry_fac_pubs/390