Work

Diazotrophs: An Overlooked Sink of N 2 O

Year: 2025

Type: article

Abstract: The ocean is the second‐largest source of greenhouse gas nitrous oxide (O). However, its role as an O sink is severely overlooked. O fixation by diazotrophs has lately been proposed as a new pathway of O consumption. We investigated diazotrophic O consumption and examined the anthropogenic influence on O dynamics in the coastal northeastern Arabian Sea, a hotspot of O emissions. Our findings reveal that relatively unperturbed waters, unlike anthropogenically perturbed waters, are a modest net O sink (98 29 saturation), contrary to previous reports. O fixation remains active in anthropogenically perturbed waters in contrast to fixation. We additionally provide evidence that the absence of control incubations leads to incorrect fixation rate estimates, further implying that oceanic dark carbon fixation rates might be overestimated. We suggest that O fixation not only directly sequesters O but may correspond to 0.3 Tg C of global ocean net primary production.

Source: Geophysical Research Letters

DOI: 10.1029/2024gl114117

Authors: Himanshu Saxena, Shreya Mehta, Sipai Nazirahmed, Jitender Kumar, Sanjeev Kumar, Arvind Singh

Institutions: Physical Research Laboratory, University of Bologna, Indian Institute of Technology Gandhinagar, Gujarat University

Language: English

Topic: Marine and coastal ecosystems

Subfield: Oceanography

Field: Earth and Planetary Sciences

Domain: Physical Sciences

SDGs: Climate action, Life below water

Open Access status: gold

Estimated APC paid: $3,190