O2 and H2O are each the source of one O in NO−2 produced from NH3 by Nitrosomonas: 15N‐NMR evidence

Andersson, Karin; Hooper, Alan B.

doi:10.1016/0014-5793(83)80292-0

Cited by 337 publications

(177 citation statements)

References 9 publications

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“…14 and 19, Table S1). Streamwater δ 18 O NO3 values averaged −3.3‰ at baseflow (Table 1), slightly lighter than the theoretically expected value (14,26,27) of microbially produced NO 3 − at this site of 1.7 ± 0.1‰, as the combination of one oxygen atom from air (δ 18 O O2 = 23.5‰) and two from local water (δ 18 O H2O = −9.2 ± 0.2‰). This difference is likely due to well-documented kinetic isotope effects during nitrite oxidation and incorporation of water by nitrite reductase, and exchange of oxygen between NO 2 − and water during nitrification (16,(28)(29)(30) − from an event (9.1 mm) on 9 July.…”

Section: Significancementioning

confidence: 55%

“…Together, these measurements indicate that microbially produced δ 15 N NO3 could approach 7.5‰ in mineral soils or could be considerably lighter, particularly in surface soils, assumed here to range to −10‰ (14). The δ 18 O NO3 value for NO 3 − produced by microbial nitrification with no kinetic isotope effects or oxygen exchange should reflect nitrifier acquisition of two oxygen atoms from water and one from atmospheric O 2 (δ 18 O NO3-nitrification = 2/3 δ 18 O H2O + 1/3 δ 18 O O2 ) (14,26,27). The δ 18 O H2O composition of streamwater and shallow groundwater during the sampling period was −9.2 ± 0.2‰ (n = 17) and the established value for δ 18 O O2 of air is 23.5‰, yielding a value of δ 18 O NO3 of 1.7‰ ± 0.1‰.…”

Section: Methodsmentioning

confidence: 99%

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Isotopic signals of summer denitrification in a northern hardwood forested catchment

Wexler

Goodale

McGuire

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Despite decades of measurements, the nitrogen balance of temperate forest catchments remains poorly understood. Atmospheric nitrogen deposition often greatly exceeds streamwater nitrogen losses; the fate of the remaining nitrogen is highly uncertain. Gaseous losses of nitrogen to denitrification are especially poorly documented and are often ignored. Here, we provide isotopic evidence (δ 15 N NO3 and δ 18 O NO3 ) from shallow groundwater at the Hubbard Brook Experimental Forest indicating extensive denitrification during midsummer, when transient, perched patches of saturation developed in hillslopes, with poor hydrological connectivity to the stream, while streamwater showed no isotopic evidence of denitrification. During small rain events, precipitation directly contributed up to 34% of streamwater nitrate, which was otherwise produced by nitrification. Together, these measurements reveal the importance of denitrification in hydrologically disconnected patches of shallow groundwater during midsummer as largely overlooked control points for nitrogen loss from temperate forest catchments.M any forested catchments export far less nitrogen (N) in streamwater than they receive in atmospheric deposition (1, 2). The rest of the deposited N may accumulate in vegetation or soil organic matter, or be lost in gaseous form. Losses of N to denitrification, the microbial reduction of aqueous nitrate (NO 3 − ) to nitrous oxide (N 2 O, a greenhouse gas) and N 2 gas, are extremely difficult to measure due to the difficulty in directly measuring N 2 fluxes and due to the high degree of spatiotemporal variability in redox conditions and substrate sources (3). Many past studies using a range of measurements (streamwater nitrate isotopic composition, the acetylene block technique, N 2 O emissions, and mass balance calculations) have concluded that denitrification in temperate forests is highly uncertain or generally unimportant (e.g., refs. 4-8).Nitrogen budgets are particularly perplexing in the northern hardwood forests at the Hubbard Brook Experimental Forest (HBEF) in the White Mountains of New Hampshire, USA, where atmospheric deposition has supplied 6-8 kg N ha −1 ·yr −1 for half a century, a rate ∼5-10 times preindustrial levels (7-10). Accumulation of N in plant biomass ceased in the early 1990s (10, 11), while streamwater inorganic N export from catchments across the HBEF and nearby streams decreased to <1 kg N ha −1 ·yr −1 , for reasons that remain elusive (9,10,12). These N flux measurements imply increasingly important roles for N gas loss or storage in soil organic matter. However, both processes are so difficult to quantify that the fate, drivers, and consequences of the "missing" N remain unknown, at the HBEF and elsewhere (8)(9)(10)12 Table S1).Nitrate isotopic composition reflects not only NO 3 − sources but also fractionation from a range of processes (14, Table S1), including the HBEF (10, 17), have revealed little if any isotopic evidence of denitrification. SignificanceDenitrification is the most poorly under...

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Section: Significancementioning

confidence: 55%

Section: Methodsmentioning

confidence: 99%

Isotopic signals of summer denitrification in a northern hardwood forested catchment

Wexler

Goodale

McGuire

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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“…Further, in the absence of NH + 4 accumulation in these sediments, the δ 15 N NTR is equal to the source of NH + 4 being oxidized to NO − 3 , which is related to the δ 15 N of the organic matter being remineralized. The δ 18 O NTR stems from a combination of factors including the δ 18 O of the water and dissolved O 2 as well as the expression of kinetic isotope effects associated with the incorporation of O atoms from these pools Casciotti et al, 2010;Andersson and Hooper, 1983). Below, we use the model to optimize and predict these values and to explore the sensitivity of rate estimates to 15 ε DNF .…”

Section: Diffusion-reaction Modelmentioning

confidence: 99%

Nitrogen cycling in the deep sedimentary biosphere: nitrate isotopes in porewaters underlying the oligotrophic North Atlantic

et al. 2015

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Abstract. Nitrogen (N) is a key component of fundamental biomolecules. Hence, its cycling and availability are central factors governing the extent of ecosystems across the Earth. In the organic-lean sediment porewaters underlying the oligotrophic ocean, where low levels of microbial activity persist despite limited organic matter delivery from overlying water, the extent and modes of nitrogen transformations have not been widely investigated. Here we use the N and oxygen (O) isotopic composition of porewater nitrate (NO − 3 ) from a site in the oligotrophic North Atlantic (Integrated Ocean Drilling Program -IODP) to determine the extent and magnitude of microbial nitrate production (via nitrification) and consumption (via denitrification). We find that NO − 3 accumulates far above bottom seawater concentrations (∼ 21 µM) throughout the sediment column (up to ∼ 50 µM) down to the oceanic basement as deep as 90 m b.s.f. (below sea floor), reflecting the predominance of aerobic nitrification/remineralization within the deep marine sediments. Large changes in the δ 15 N and δ 18 O of nitrate, however, reveal variable influence of nitrate respiration across the three sites. We use an inverse porewater diffusion-reaction model, constrained by the N and O isotope systematics of nitrification and denitrification and the porewater NO − 3 isotopic composition, to estimate rates of nitrification and denitrification throughout the sediment column. Results indicate variability of reaction rates across and within the three boreholes that are generally consistent with the differential distribution of dissolved oxygen at this site, though not necessarily with the canonical view of how redox thresholds separate nitrate regeneration from dissimilative consumption spatially. That is, we provide stable isotopic evidence for expanded zones of co-occurring nitrification and denitrification. The isotope biogeochemical modeling also yielded estimates for the δ 15 N and δ 18 O of newly produced nitrate (δ 15 N NTR (NTR, referring to nitrification) and δ 18 O NTR ), as well as the isotope effect for denitrification ( 15 ε DNF ) (DNF, referring to denitrification), parameters with high relevance to global ocean models of N cycling. Estimated values of δ 15 N NTR were generally lower than previously reported δ 15 N values for sinking particulate organic nitrogen in this region. We suggest that these values may be, in part, related to sedimentary N 2 fixation and remineralization of the newly fixed organic N. Values of δ 18 O NTR generally ranged between −2.8 and 0.0 ‰, consistent with recent estimates based on lab cultures of nitrifying bacteria. Notably, some δ 18 O NTR values were elevated, suggesting incorporation of 18 O-enriched dissolved oxygen during nitrification, and possibly indicating a tight coupling of NH + 4 and NO − 2 oxidation in this metabolically sluggish environment. Our findings indicate that the production of organic matter by in situ autotrophy (e.g., nitrification, nitrogen fixation) supplies a large fraction of the...

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“…Corresponding to this widely spread occurrence their metabolism is flexible; they gain energy using three different pathways, one oxic and two anoxic. The mechanism of aerobic ammonia oxidation was the first pathway discovered (Rees & Nason, 1966;Hooper, 1969a;Hyman & Wood, 1985;Arciero & Hooper, 1993;Hyman & Arp, 1993;Bergmann et al, 1994;Sayavedra-Soto et al, 1994;Dua et al, 1979;Anderson & Hooper, 1983). Later, Abeliovich & Vonshak (1992) and Bock et al (1995) described a heterotrophic and hydrogen-dependent denitrification as an alternative pathway.…”

Section: Introductionmentioning

confidence: 99%

Ammonium and hydroxylamine uptake and accumulation in Nitrosomonas

et al. 2004

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Starved cells of Nitrosomonas europaea and further ammonia oxidizers were able to rapidly accumulate ammonium and hydroxylamine to an internal concentration of about 1 and 0·8 M, respectively. In kinetic studies, the uptake/accumulation rates for ammonium [3·1 mmol (g protein)−1 min−1] and hydroxylamine [4·39 mmol (g protein)−1 min−1] were determined. The uptake and accumulation process of ammonium and hydroxylamine was not coupled to ammonia or hydroxylamine oxidation and nitrite was not produced. In the presence of uncouplers the ammonium accumulation was completely inhibited, indicating an active, membrane-potential-driven transport mechanism. When the external ammonium or hydroxylamine pool was depleted, the internal ammonium and hydroxylamine was consumed within 12 h or 20 min, respectively. The binding of ammonium/ammonia was correlated with an energized membrane system, and hydroxylamine may bind to the hydroxylamine oxidoredutase.

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O₂ and H₂O are each the source of one O in NO⁻₂ produced from NH₃ by Nitrosomonas: ¹⁵N‐NMR evidence

Cited by 337 publications

References 9 publications

Isotopic signals of summer denitrification in a northern hardwood forested catchment

Isotopic signals of summer denitrification in a northern hardwood forested catchment

Nitrogen cycling in the deep sedimentary biosphere: nitrate isotopes in porewaters underlying the oligotrophic North Atlantic

Ammonium and hydroxylamine uptake and accumulation in Nitrosomonas

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