Hydroxylamine as a Potential Indicator of Nitrification in the Open Ocean

Korth, Frederike; Kock, Annette; Arévalo‐Martínez, Damian L.; Bange, Hermann W.

doi:10.1029/2018gl080466

Cited by 14 publications

(19 citation statements)

References 59 publications

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“…2 and 3), a hybrid formation of one nitrogen atom from NH + 4 and one from NO − 2 (Eq. 4) is assumed to be taking place as found in archaeal ammo-nia oxidizers (Kozlowski et al, 2016). In incubations with 15 NO − 2 , we assume that 46 N 2 O comes from nitrifier denitrification or denitrification, which cannot be distinguished (Eq.…”

Section: Isotope Measurement and Rate Determinationmentioning

confidence: 99%

“…While hydroxylamine (NH 2 OH) was long thought to be the only obligate intermediate in AO, NO has recently been identified as an obligate intermediate for AOB (Caranto and Lancaster, 2017) and presumably AOA (Carini et al, 2018). Both intermediates are present in and around ODZs and correlated with nitrification activity (Lutterbeck et al, 2018;Korth et al, 2019). Specific details about the precursor of NO to form N 2 O in AOA remain controversial.…”

mentioning

confidence: 99%

“…Stiegelmeier et al (2014) concluded that NO is derived from NO − 2 reduction to form N 2 O, while Carini et al (2018) hypothesized that NO is derived from NH 2 OH oxidation, which can then form N 2 O. A hybrid N 2 O production mechanism in AOA has been suggested, where NO from NO − 2 reacts with NH 2 OH from NH + 4 , which is thought to be abiotic, i.e., nonenzymatic (Kozlowski et al, 2016). Abiotic N 2 O production, also known as chemodenitrification, from intermediates like NH 2 OH, NO or NO − 2 can occur under acidic conditions (Frame et al, 2017), or in the presence of reduced metals like Fe or Mn and catalyzing surfaces (Zhu-Barker et al, 2015), but the evidence of abiotic N 2 O production/chemodenitrification in ODZs is still lacking.…”

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confidence: 99%

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Regulation of nitrous oxide production in low-oxygen waters off the coast of Peru

et al. 2020

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Abstract. Oxygen-deficient zones (ODZs) are major sites of net natural nitrous oxide (N2O) production and emissions. In order to understand changes in the magnitude of N2O production in response to global change, knowledge on the individual contributions of the major microbial pathways (nitrification and denitrification) to N2O production and their regulation is needed. In the ODZ in the coastal area off Peru, the sensitivity of N2O production to oxygen and organic matter was investigated using 15N tracer experiments in combination with quantitative PCR (qPCR) and microarray analysis of total and active functional genes targeting archaeal amoA and nirS as marker genes for nitrification and denitrification, respectively. Denitrification was responsible for the highest N2O production with a mean of 8.7 nmol L−1 d−1 but up to 118±27.8 nmol L−1 d−1 just below the oxic–anoxic interface. The highest N2O production from ammonium oxidation (AO) of 0.16±0.003 nmol L−1 d−1 occurred in the upper oxycline at O2 concentrations of 10–30 µmol L−1 which coincided with the highest archaeal amoA transcripts/genes. Hybrid N2O formation (i.e., N2O with one N atom from NH4+ and the other from other substrates such as NO2-) was the dominant species, comprising 70 %–85 % of total produced N2O from NH4+, regardless of the ammonium oxidation rate or O2 concentrations. Oxygen responses of N2O production varied with substrate, but production and yields were generally highest below 10 µmol L−1 O2. Particulate organic matter additions increased N2O production by denitrification up to 5-fold, suggesting increased N2O production during times of high particulate organic matter export. High N2O yields of 2.1 % from AO were measured, but the overall contribution by AO to N2O production was still an order of magnitude lower than that of denitrification. Hence, these findings show that denitrification is the most important N2O production process in low-oxygen conditions fueled by organic carbon supply, which implies a positive feedback of the total oceanic N2O sources in response to increasing oceanic deoxygenation.

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Section: Isotope Measurement and Rate Determinationmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Regulation of nitrous oxide production in low-oxygen waters off the coast of Peru

et al. 2020

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“…While hydroxylamine (NH2OH) was long thought to be the only obligate intermediate in AO, NO has 65 recently been identified as an obligate intermediate for AOB (Caranto and Lancaster 2017) and presumably AOA (Carini et al 2018). Both intermediates are present in and around ODZs and correlated with nitrification activity (Lutterbeck et al 2018, Korth et al 2019. Specific details about the precursor of NO to form N2O in AOA remains controversial.…”

mentioning

confidence: 99%

“…Hybrid N2O production from NH4 + was independent of the rate at which N2O production took place 530 and independent of the O2 concentration and varied little (70 -86% of total N2O production) during AO. Therefore, a purely abiotic reaction outside and without the vicinity of the cell can be excluded because concentrations of potential substrates for abiotic N2O production like Fe(II), Mn, NO, NH2OH vary with depth and O2 concentration (Zhu-Barker et al 2015, Kondo and Moffet 2015, Lutterbeck et al 2018, Korth et al 2019. Hence, any 14 N which is integrated into N2O to produce a hybrid/single labelled N2O has to be passively or actively taken up by the cell 535 first (Figure 9).…”

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confidence: 99%

Regulation of nitrous oxide production in low oxygen waters off the coast of Peru

Frey¹,

Bange²,

Achterberg³

et al. 2019

Preprint

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Abstract. Oxygen deficient zones (ODZs) are major sites of net natural nitrous oxide (N2O) production and emissions. In order to understand changes in the magnitude of N2O production in response to global change, knowledge on the individual contributions of the major microbial pathways (nitrification and denitrification) to N2O production and their regulation is needed. In the ODZ in the coastal area off Peru, the sensitivity of N2O production to oxygen and organic matter was investigated using 15N-tracer experiments in combination with qPCR and microarray analysis of total and active functional genes targeting archaeal amoA and nirS as marker genes for nitrification and denitrification, respectively. Denitrification was responsible for the highest N2O production with a mean of 8.7&#8201;nmol&#8201;L&#8722;1&#8201;d&#8722;1 but up to 118&#8201;&#177;&#8201;27.8&#8201;nmol&#8201;L&#8722;1&#8201;d&#8722;1 just below the oxic-anoxic interface. Highest N2O production from ammonium oxidation (AO) of 0.16&#8201;&#177;&#8201;0.003&#8201;nmol&#8201;L&#8722;1&#8201;d&#8722;1 occurred in the upper oxycline at O2 concentrations of 10&#8211;30&#8201;&#181;mol&#8201;L&#8722;1 which coincided with highest archaeal amoA transcripts/genes. Oxygen responses of N2O production varied with substrate, but production and yields were generally highest below 10&#8201;&#181;mol&#8201;L&#8722;1&#8201;O2. Particulate organic matter additions increased N2O production by denitrification up to 5-fold suggesting increased N2O production during times of high particulate organic matter export. High N2O yields of 2.1&#8201;% from AO were measured, but the overall contribution by AO to N2O production was still an order of magnitude lower than that of denitrification. Hence, these findings show that denitrification is the most important N2O production process in low oxygen conditions fueled by organic carbon supply, which implies a positive feedback of the total oceanic N2O sources in response to increasing oceanic deoxygenation.

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Sample preservation methods for nitrous oxide concentration and isotope ratio measurements in aquatic environments

Frey,

Tang,

Ward

et al. 2024

Limnology & Ocean Methods

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The nitrogen (N) and oxygen (O) stable isotope analysis of dissolved nitrous oxide (N2O) can provide important constraints on the sources and cycling of N2O in aquatic environments. The isotopic composition of aqueous N2O, both in field (natural abundance) or experimental (15N‐labeling) samples, however, may be altered by abiotic reactions involving nitrite () or hydroxylamine (NH2OH) and microbial activity during sample storage, if samples are not adequately preserved. Here we tested five different preservatives, mercuric chloride (HgCl2), copper sulfate (CuSO4), zinc chloride (ZnCl2), hydrochloric acid (HCl) mixed with sulfamic acid (SFA), and sodium hydroxide (NaOH), for fixing natural water samples from an estuary and a lake with different concentrations over a range of different storage times for N2O analyses. ZnCl2 and CuSO4 decreased the pH, and led to abiotic N2O production from , shifting the N2O isotopic composition significantly. Removal of with a mixture of SFA and HCl did not always prevent the alteration of the original N and O isotope composition of N2O, confirming the requirement for complete removal, and underscoring the biasing effects of at very low pH, even at trace levels. At low background, HgCl2 preservation led to robust and accurate results. However, in light of its toxicity and bioaccumulation potential in food webs, this fixative should be avoided. The addition of NaOH reduced abiotic side reactions involving , and yielded the most reliable and reproducible results for N2O concentration and isotope ratio measurements across tested settings and storage times.

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Hydroxylamine as a Potential Indicator of Nitrification in the Open Ocean

Cited by 14 publications

References 59 publications

Regulation of nitrous oxide production in low-oxygen waters off the coast of Peru

Regulation of nitrous oxide production in low-oxygen waters off the coast of Peru

Regulation of nitrous oxide production in low oxygen waters off the coast of Peru

Sample preservation methods for nitrous oxide concentration and isotope ratio measurements in aquatic environments

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