Unexpectedly high degree of anammox and DNRA in seagrass sediments: Description and application of a revised isotope pairing technique

Salk, Kateri R.; Erler, Dirk V.; Eyre, Bradley D.; Carlson-Perret, Natasha L.; Ostrom, Nathaniel E.

doi:10.1016/j.gca.2017.05.012

Cited by 52 publications

(43 citation statements)

References 68 publications

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“…The IPT has gone through several iterations since its initial development due to the discovery of new processes and their potential co‐occurrence (Risgaard‐Petersen et al ; Trimmer et al ; Song et al , ; Salk et al ). The basis of the IPT is that the addition of labeled 15 NO 3 − to the overlying water and its subsequent diffusion into the NO 3 − ‐reducing zone can be used to trace the production of 15 N‐N 2 gas ( 30 N 2 , 29 N 2 ) despite a high atmospheric 14 N‐N 2 ( 28 N 2 ) background as well as other 15 N‐labeled end products ( 45 N 2 O, 46 N 2 O, 15 NH 4 + ).…”

Section: Evolution Of the Whole‐core Iptmentioning

confidence: 99%

“…Calculations have therefore been further revised for slurries (Song et al ) and whole‐core experiments (Song et al ; Salk et al ). In addition to N 2 , the isotopic composition of NH 4 + (Song et al , ; Salk et al ) and of N 2 O (Salk et al ) are measured throughout incubations to enable differentiation between coupled anammox‐DNRA and canonical anammox.…”

Section: Evolution Of the Whole‐core Iptmentioning

confidence: 99%

“…In the most recent iterations of the whole‐core IPT, the contribution of three co‐occurring NO 3 − ‐reducing processes (denitrification, anammox, DNRA) can be determined. These modifications require additional samples to determine the fraction and progressive accumulation of 15 NH 4 + in the total NH 4 + pool (through 15 NO 3 − reduction via DNRA) within the NO 3 − ‐reducing zone of whole‐core incubations and in parallel slurry incubations (Song et al ; Salk et al ). Increasing observations of co‐occurring NO 3 − ‐reducing processes demonstrate further that we lack some understanding of the controlling factors of when these processes occur together.…”

Section: Evolution Of the Whole‐core Iptmentioning

confidence: 99%

“…These two incubation types are discussed in greater detail in "General use of whole-core IPT" section. For the purpose of this review, we herein refer to IPT (Nielsen 1992), r-IPT , and other revised/updated calculations (e.g., Song et al 2016;Salk et al 2017) collectively as "IPT." The determination of DNRA through experimental 15 NO 3 − addition has been carried out for many years (Koike and Hattori 1978;Sørensen 1978;Jørgensen 1989;Binnerup et al 1992).…”

Section: Evolution Of the Whole-core Iptmentioning

confidence: 99%

“…The calculation of rates using the IPT relies on the central assumption that denitrification is the only N 2 ‐producing processes, and specific relationships between 15 N and 14 N distribution both in NO 3 − in the NO 3 − ‐reducing zone and in the resulting 15 N‐N 2 species (discussed in “Evolution of the whole‐core IPT” section of this manuscript). Since its original development, the whole‐core IPT, along with its assumptions and associated calculations have been revised on several occasions to account for the presence of anammox as an additional N 2 ‐producing process (Risgaard‐Petersen et al ; Trimmer et al ) and the co‐occurrence of denitrification, anammox, and DNRA at some locations (Song et al ; Salk et al ). The application of the IPT across a wide range of environments has added substantially to our understanding of how the N cycle is controlled in aquatic environments.…”

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confidence: 99%

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Application of the isotope pairing technique in sediments: Use, challenges, and new directions

Robertson

Bartoli

Brüchert

et al. 2019

Limnology & Ocean Methods

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Determining accurate rates of benthic nitrogen (N) removal and retention pathways from diverse environments is critical to our understanding of process distribution and constructing reliable N budgets and models. The whole‐core 15N isotope pairing technique (IPT) is one of the most widely used methods to determine rates of benthic nitrate‐reducing processes and has provided valuable information on processes and factors controlling N removal and retention in aquatic systems. While the whole core IPT has been employed in a range of environments, a number of methodological and environmental factors may lead to the generation of inaccurate data and are important to acknowledge for those applying the method. In this review, we summarize the current state of the whole core IPT and highlight some of the important steps and considerations when employing the technique. We discuss environmental parameters which can pose issues to the application of the IPT and may lead to experimental artifacts, several of which are of particular importance in environments heavily impacted by eutrophication. Finally, we highlight the advances in the use of the whole‐core IPT in combination with other methods, discuss new potential areas of consideration and encourage careful and considered use of the whole‐core IPT. With the recognition of potential issues and proper use, the whole‐core IPT will undoubtedly continue to develop, improve our understanding of benthic N cycling and allow more reliable budgets and predictions to be made.

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Section: Evolution Of the Whole‐core Iptmentioning

confidence: 99%

Section: Evolution Of the Whole‐core Iptmentioning

confidence: 99%

Section: Evolution Of the Whole‐core Iptmentioning

confidence: 99%

Section: Evolution Of the Whole-core Iptmentioning

confidence: 99%

mentioning

confidence: 99%

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Application of the isotope pairing technique in sediments: Use, challenges, and new directions

Robertson

Bartoli

Brüchert

et al. 2019

Limnology & Ocean Methods

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Denitrification, anammox, and dissimilatory nitrate reduction to ammonium across a mosaic of estuarine benthic habitats

Chen

Erler

Hipsey

et al. 2020

Limnology & Oceanography

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Estuaries play a key role in moderating the flow of nitrogen (N) to marine ecosystems. However, the magnitude of this N removal can vary dramatically both within and between estuaries due to the benthic habitats present. Here, we compare denitrification, coupled nitrification–denitrification, anammox, and dissimilatory nitrate reduction to ammonium (DNRA) across a mosaic of benthic habitats in the subtropical Noosa River Estuary, Australia. Using 15N tracer techniques and passive pore‐water samplers, we show that coupled nitrification–denitrification was the dominant pathway for N2 production across all habitats, with higher rates in vegetated habitats (10–70 μmol N m−2 h−1) compared to bare sediments (0.9–2 μmol N m−2 h−1). Unusual pore‐water profiles in the macroalgal sediments suggest the presence of sulfur‐driven anoxic nitrification of NH4+ to NO3− and N2. A benthic N budget showed that combined denitrification and coupled nitrification–denitrification accounted approximately 96% of the N2 production, while DNRA accounted for 9% of total NO3− reduction pathways in the Noosa River Estuary. The macroalgae habitat contributed 76% of total N removal via N2 production and 65% of N retention via DNRA, despite accounting for only 25% of the total surface area. We show a strong relationship between seagrass and macroalgae area and N2 production (r2 = 0.8; p < 0.01), and as such, the capacity to mitigate reactive N loads in estuaries may decrease with the large‐scale loss of seagrass and other vegetated habitats.

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Hierarchy of factors controls denitrification rates in temperate intermittently closed and open coastal lakes/lagoons (ICOLLS)

et al. 2019

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Unexpectedly high degree of anammox and DNRA in seagrass sediments: Description and application of a revised isotope pairing technique

Cited by 52 publications

References 68 publications

Application of the isotope pairing technique in sediments: Use, challenges, and new directions

Application of the isotope pairing technique in sediments: Use, challenges, and new directions

Denitrification, anammox, and dissimilatory nitrate reduction to ammonium across a mosaic of estuarine benthic habitats

Hierarchy of factors controls denitrification rates in temperate intermittently closed and open coastal lakes/lagoons (ICOLLS)

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