Nitrogen and oxygen isotopomeric constraints on the origins and sea‐to‐air flux of N<sub>2</sub>O in the oligotrophic subtropical North Pacific gyre

Popp, Brian N.; Westley, Marian B.; Toyoda, Sakae; Miwa, Tatsuya; Dore, John E.; Yoshida, Naohiro; Rust, Terri M.; Sansone, Francis J.; Russ, Mary E.; Ostrom, Nathaniel E.; Ostrom, Peggy H.

doi:10.1029/2001gb001806

Cited by 135 publications

(197 citation statements)

References 63 publications

(104 reference statements)

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“…As this is a diffusion-driven process, it is mass dependent and given the difference in bond energy required for breakage of the N-O bond a slight effect on SP is expected. This is also in line with the kinetic isotope effect theory which suggest a small offset towards higher α and therefore higher SP (Popp et al, 2002;Tilsner et al, 2003;Wrage et al, 2004;Well and Flessa, 2008).…”

Section: Discussionsupporting

confidence: 91%

“…According to kinetic isotope theory, the cleavage of N 2 O is expected to fractionate in favor of the 15 N α molecule, due to a stronger 15 N−O bond compared to the 14 N−O (Popp et al, 2002), diffusion into the cell (Tilsner et al, 2003), and enzymatic reduction . N 2 O reduction during bacterial denitrification is therefore expected to lead to an increase in SP.…”

Section: Introductionmentioning

confidence: 99%

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Continuous measurements of nitrous oxide isotopomers during incubation experiments

et al. 2018

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Abstract. Nitrous oxide (N 2 O) is an important and strong greenhouse gas in the atmosphere. It is produced by microbes during nitrification and denitrification in terrestrial and aquatic ecosystems. The main sinks for N 2 O are turnover by denitrification and photolysis and photo-oxidation in the stratosphere. In the linear N=N=O molecule 15 N substitution is possible in two distinct positions: central and terminal. The respective molecules, 14 N 15 N 16 O and 15 N 14 N 16 O, are called isotopomers. It has been demonstrated that N 2 O produced by nitrifying or denitrifying microbes exhibits a different relative abundance of the isotopomers. Therefore, measurements of the site preference (difference in the abundance of the two isotopomers) in N 2 O can be used to determine the source of N 2 O, i.e., nitrification or denitrification. Recent instrument development allows for continuous positiondependent δ 15 N measurements at N 2 O concentrations relevant for studies of atmospheric chemistry. We present results from continuous incubation experiments with denitrifying bacteria, Pseudomonas fluorescens (producing and reducing N 2 O) and Pseudomonas chlororaphis (only producing N 2 O). The continuous measurements of N 2 O isotopomers reveals the transient isotope exchange among KNO 3 , N 2 O, and N 2 . We find bulk isotopic fractionation of −5.01 ‰ ± 1.20 for P. chlororaphis, in line with previous results for production from denitrification. For P. fluorescens, the bulk isotopic fractionation during production of N 2 O is −52.21 ‰ ± 9.28 and 8.77 ‰ ± 4.49 during N 2 O reduction.The site preference (SP) isotopic fractionation for P. chlororaphis is −3.42 ‰ ± 1.69. For P. fluorescens, the calculations result in SP isotopic fractionation values of 5.73 ‰ ± 5.26 during production of N 2 O and 2.41 ‰ ± 3.04 during reduction of N 2 O. In summary, we implemented continuous measurements of N 2 O isotopomers during incubation of denitrifying bacteria and believe that similar experiments will lead to a better understanding of denitrifying bacteria and N 2 O turnover in soils and sediments and ultimately hands-on knowledge on the biotic mechanisms behind greenhouse gas exchange of the globe.

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Section: Discussionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Continuous measurements of nitrous oxide isotopomers during incubation experiments

et al. 2018

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“…Surprisingly, the d 15 N bulk -N 2 O values of a marine AOA strain CN25 were positive (8.7%) (Santoro et al, 2011), which differed significantly from the ideal isotope fractionation effect and from those of the soil AOA strains. These values were similar to those from surface oceans and the troposphere (5% to 10%) (Kim and Craig, 1993;Rahn and Wahlen, 2000;Popp et al, 2002). Strain AR was also from a marine environment but its d 15 N bulk value (-12.91%) was similar to those of the soil AOA strains and marine AOB (Frame and Casciotti, 2010 Only 10% of the ammonia (0.1 mM) was oxidized in this condition, possibly because of high sensitivity to the accumulated nitrite.…”

Section: Aoa Strainssupporting

confidence: 58%

Isotopic signatures of N2O produced by ammonia-oxidizing archaea from soils

Well²,

et al. 2013

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N 2 O gas is involved in global warming and ozone depletion. The major sources of N 2 O are soil microbial processes. Anthropogenic inputs into the nitrogen cycle have exacerbated these microbial processes, including nitrification. Ammonia-oxidizing archaea (AOA) are major members of the pool of soil ammonia-oxidizing microorganisms. This study investigated the isotopic signatures of N 2 O produced by soil AOA and associated N 2 O production processes. All five AOA strains (I.1a, I.1a-associated and I.1b clades of Thaumarchaeota) from soil produced N 2 O and their yields were comparable to those of ammonia-oxidizing bacteria (AOB). The levels of site preference (SP), d 15 N bulk and d 18 O -N 2 O of soil AOA strains were 13-30%, À 13 to À 35% and 22-36%, respectively, and strains MY1-3 and other soil AOA strains had distinct isotopic signatures. A 15 N-NH 4 þ -labeling experiment indicated that N 2 O originated from two different production pathways (that is, ammonia oxidation and nitrifier denitrification), which suggests that the isotopic signatures of N 2 O from AOA may be attributable to the relative contributions of these two processes. The highest N 2 O production yield and lowest site preference of acidophilic strain CS may be related to enhanced nitrifier denitrification for detoxifying nitrite. Previously, it was not possible to detect N 2 O from soil AOA because of similarities between its isotopic signatures and those from AOB. Given the predominance of AOA over AOB in most soils, a significant proportion of the total N 2 O emissions from soil nitrification may be attributable to AOA.

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“…N 2 O is subsequently stripped from the vial, cryofocused (Sansone et al, 1997) and introduced into the carrier stream of a Finnigan MAT252 mass spectrometer through an online gas chromatographic front end. N 2 O is thereby separated from residual CO 2 and its d 15 N value determined from masses 44, 45 and 46 as described previously (Dore et al, 1998;Popp et al, 2002). Uptake of 15 N into particulate matter was not measured and rates were not corrected for isotope dilution due to NH 4 þ turnover; that is, oxidation rates were calculated based on the accumulation of 15 N in the NO 3 À plus NO 2 À pool relative to the initial 15 N-labeled NH 4 þ pool without further adjustment.…”

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confidence: 99%

Molecular and biogeochemical evidence for ammonia oxidation by marine Crenarchaeota in the Gulf of California

2008

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Nitrification plays an important role in marine biogeochemistry, yet efforts to link this process to the microorganisms that mediate it are surprisingly limited. In particular, ammonia oxidation is the first and rate-limiting step of nitrification, yet ammonia oxidation rates and the abundance of ammoniaoxidizing bacteria (AOB) have rarely been measured in tandem. Ammonia oxidation rates have not been directly quantified in conjunction with ammonia-oxidizing archaea (AOA), although mounting evidence indicates that marine Crenarchaeota are capable of ammonia oxidation, and they are among the most abundant microbial groups in the ocean. Here, we have directly quantified ammonia oxidation rates by 15 N labeling, and AOA and AOB abundances by quantitative PCR analysis of ammonia monooxygenase subunit A (amoA) genes, in the Gulf of California. Based on markedly different archaeal amoA sequence types in the upper water column (60 m) and oxygen minimum zone (OMZ; 450 m), novel amoA PCR primers were designed to specifically target and quantify 'shallow' (group A) and 'deep' (group B) clades. These primers recovered extensive variability with depth. Within the OMZ, AOA were most abundant where nitrification may be coupled to denitrification. In the upper water column, group A tracked variations in nitrogen biogeochemistry with depth and between basins, whereas AOB were present in relatively low numbers or undetectable. Overall, 15 NH 4 þ oxidation rates were remarkably well correlated with AOA group A amoA gene copies (r 2 ¼ 0.90, Po0.001), and with 16S rRNA gene copies from marine Crenarchaeota (r 2 ¼ 0.85, Po0.005). These findings represent compelling evidence for an archaeal role in oceanic nitrification.

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Nitrogen and oxygen isotopomeric constraints on the origins and sea‐to‐air flux of N₂O in the oligotrophic subtropical North Pacific gyre

Abstract: [1] Although the oceans are a significant source of the greenhouse gas nitrous oxide (N 2 O) to the atmosphere, the magnitude and characteristics of this source are poorly constrained. We present here stable isotope and isotopomer (intramolecular distribution of 15

Cited by 135 publications

References 63 publications

Continuous measurements of nitrous oxide isotopomers during incubation experiments

Continuous measurements of nitrous oxide isotopomers during incubation experiments

Isotopic signatures of N2O produced by ammonia-oxidizing archaea from soils

Molecular and biogeochemical evidence for ammonia oxidation by marine Crenarchaeota in the Gulf of California

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Nitrogen and oxygen isotopomeric constraints on the origins and sea‐to‐air flux of N2O in the oligotrophic subtropical North Pacific gyre

Abstract: [1] Although the oceans are a significant source of the greenhouse gas nitrous oxide (N 2 O) to the atmosphere, the magnitude and characteristics of this source are poorly constrained. We present here stable isotope and isotopomer (intramolecular distribution of 15

Cited by 135 publications

References 63 publications

Continuous measurements of nitrous oxide isotopomers during incubation experiments

Continuous measurements of nitrous oxide isotopomers during incubation experiments

Isotopic signatures of N2O produced by ammonia-oxidizing archaea from soils

Molecular and biogeochemical evidence for ammonia oxidation by marine Crenarchaeota in the Gulf of California

Contact Info

Product

Resources

About

Nitrogen and oxygen isotopomeric constraints on the origins and sea‐to‐air flux of N₂O in the oligotrophic subtropical North Pacific gyre