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Updated: Jan 8, 2026

Estimating Sediment Denitrification Rates Using Cores and N2O Microsensors

Estimating Sediment Denitrification Rates Using Cores and N2O Microsensors

Published on: December 6, 2018

貧栄養の有光層海洋におけるN2O生成への尿素駆動型硝化の寄与

Ting Gu^1,2, Zhuo Chen^1,2, David A Hutchins³

¹Research Centre for Indian Ocean Ecosystem, Tianjin University of Science and Technology, Tianjin 300457, China.

The ISME journal

|December 22, 2025

Abstract:

Urea is an important alternative nitrogen source to ammonium for nitrification in oligotrophic oceans, yet its role in substrate-driven nitrous oxide (N2O) production remains poorly constrained. Here, we combined N2O isotopomer profiling, 15N-tracer incubations, and metagenomics to quantify and mechanistically resolve substrate-specific archaeal nitrification in the western tropical Pacific euphotic zone. Isotopomer-based mixing and fractionation model indicated that archaeal nitrification accounted for 69.6 ± 14.1% of microbial sources of N2O in oxygenated epipelagic waters. Depth-integrated urea-driven nitrification contributed 14-41% of total nitrification and 21-39% of nitrification-derived N2O, with contributions regulated by substrate proportions. Acidification experiments showed that pH decline inhibited ammonium-driven nitrification (median 21.9%) and enhanced urea oxidation (median 61.9%), whereas N2O production increased for both substrates (median 35.9% and 38.0%). In addition, experimental acidification induced opposite shifts in hybrid versus double-labelled N2O, suggesting pH-driven shifts N-intermediate chemistry and intracellular partitioning. Metagenomic results support the globally widespread urea-type AOA. Together, these results indicate that urea-driven nitrification constitutes a non-negligible, substrate-dependent source of N2O in oligotrophic euphotic zones. We recommend that Earth-system N-cycle models represent urea and ammonium oxidation as distinct pathways with pH-sensitive yields to improve projections of marine nitrification and N2O fluxes under acidification.

キーワード:

アンモニア酸化古細菌同位体トレーシング硝化亜酸化窒素海洋酸性化尿素酸化

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Measurement of the Potential Rates of Dissimilatory Nitrate Reduction to Ammonium Based on 14NH4+/15NH4+ Analyses via Sequential Conversion to N2O

Measurement of the Potential Rates of Dissimilatory Nitrate Reduction to Ammonium Based on 14NH4+/15NH4+ Analyses via Sequential Conversion to N2O

Published on: October 7, 2020

The Benthic Exchange of O2, N2 and Dissolved Nutrients Using Small Core Incubations

The Benthic Exchange of O2, N2 and Dissolved Nutrients Using Small Core Incubations

Published on: August 3, 2016

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Inorganic Nitrogen Assimilation

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