N2O formation by nitrite-induced (chemo)denitrification in coastal marine sediment

• Published in: Scientific reports Vol. 9; no. 1; pp. 1 - 12
• Main Authors: Otte, Julia M., Blackwell, Nia, Ruser, Reiner, Kappler, Andreas, Kleindienst, Sara, Schmidt, Caroline
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 31-07-2019; Nature Publishing Group; Nature Portfolio
• Subjects: 704/106/47; 704/47; Denitrification; Genetic transformation; Greenhouse gases; Humanities and Social Sciences; Iron; Marine sediments; Microcosms; Microorganisms; multidisciplinary; Nitrites; Nitrous oxide; Oxidation; Ozone depletion; Reductase; Science; Science (multidisciplinary); Sediments
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-019-47172-x

Nitrous oxide (N
2
O) is a potent greenhouse gas that also contributes to stratospheric ozone depletion. Besides microbial denitrification, abiotic nitrite reduction by Fe(II) (chemodenitrification) has the potential to be an important source of N
2
O. Here, using microcosms, we quantified N
2
O formation in coastal marine sediments under typical summer temperatures. Comparison between gamma-radiated and microbially-active microcosm experiments revealed that at least 15–25% of total N
2
O formation was caused by chemodenitrification, whereas 75–85% of total N
2
O was potentially produced by microbial N-transformation processes. An increase in (chemo)denitrification-based N
2
O formation and associated Fe(II) oxidation caused an upregulation of N
2
O reductase (typical
nosZ
) genes and a distinct community shift to potential Fe(III)-reducers (
Arcobacter
), Fe(II)-oxidizers (
Sulfurimonas
), and nitrate/nitrite-reducing microorganisms (
Marinobacter
). Our study suggests that chemodenitrification contributes substantially to N
2
O formation from marine sediments and significantly influences the N- and Fe-cycling microbial community.