Document Type

Article

Publication Date

2025

DOI

10.1021/acs.est.4c12913

Publication Title

Environmental Science & Technology

Volume

59

Issue

11

Pages

5607-5620

Abstract

The export of terrestrial organic matter (TOM) to the ocean has been traditionally viewed to be minimal or only of significance in near-coastal continental margins. The broadly accepted explanation for the widespread loss of terrestrial lignin biomarkers and apparent disappearance of the <-25‰ stable carbon isotopic signature (δ¹³C) of TOM is that TOM is almost fully degraded before reaching the open ocean. Oceanic carbon (δ¹³C value ≥ -22‰) is therefore thought to be derived primarily from algae. However, an alternative explanation for the different molecular and δ¹³C signatures in terrestrial and marine environments may be that oxidative processing transforms TOM to appear marine-like. To test this hypothesis, we subjected eight TOM samples to a strong oxidation gradient. At carbon losses typical of TOM degradation during transport and sedimentation (above 60%), the differentiators of provenance disappeared, leaving a residue that was marine-like both chemically (aliphatic- and nitrogen-rich) and isotopically (δ¹³C enrichment of 4 to 9‰). This challenges the validity of conventional two-endmember mixing models, suggesting that a much larger fraction than previously estimated of the organic matter found in the ocean may originate from terrestrial sources, impacting global models of carbon cycling and sequestration.

Rights

© 2025 The Authors.

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

Original Publication Citation

Goranov, A. I., Carter, S. J., Pearson, A., & Hatcher, P. G. (2025). Oxidation camouflages terrestrial organic matter to appear marine-like. Environmental Science & Technology, 59(11), 5607-5620. https://doi.org/10.1021/acs.est.4c12913

ORCID

0000-0002-5103-0838 (Goranov)

es4c12913_si_001.pdf (2244 kB)
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