Ammonium stability and nitrogen isotope fractionations for –NH3(aq)–NH3(gas) systems at 20–70°C and pH of 2–13: Applications to habitability and nitrogen cycling in low-temperature hydrothermal systems

Li, Long; Lollar, Barbara Sherwood; Li, Hong; Wortmann, Ulrich G.; Lacrampe-Couloume, Georges

doi:10.1016/j.gca.2012.01.040

Cited by 135 publications

(77 citation statements)

References 69 publications

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“…By analogy with the nitrogen isotope effect of ammonia assimilation (51,52) ⌺NH 3 ), the pH of the medium was 8.0 Ϯ 0.1 at 70°C. The fraction of NH 3 to ⌺NH 3 was then calculated to be 43% Ϯ 5% (from equation 9), and the 15 ⌬ ⌺NH3 Ϫ NH3 value in the medium was calculated to be 19‰ Ϯ 2‰ using Ϫ34‰ for the isotopic equilibrium between ammonia and ammonium at 70°C (39). In contrast, the pH of the medium was 8.2 to 8.6 at 70°C during the batch culture experiments (20 to 150 M ⌺NH 3 ).…”

Section: Discussionmentioning

confidence: 99%

Nitrogen and Oxygen Isotope Effects of Ammonia Oxidation by Thermophilic Thaumarchaeota from a Geothermal Water Stream

Nishizawa

Sakai

Konno

et al. 2016

Appl Environ Microbiol

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Ammonia oxidation regulates the balance of reduced and oxidized nitrogen pools in nature. Although ammonia-oxidizing archaea have been recently recognized to often outnumber ammonia-oxidizing bacteria in various environments, the contribution of ammonia-oxidizing archaea is still uncertain due to difficulties in the in situ quantification of ammonia oxidation activity. Nitrogen and oxygen isotope ratios of nitrite (␦ 15 N NO2؊ and ␦ 18 O NO2؊ , respectively) are geochemical tracers for evaluating the sources and the in situ rate of nitrite turnover determined from the activities of nitrification and denitrification; however, the isotope ratios of nitrite from archaeal ammonia oxidation have been characterized only for a few marine species. We first report the isotope effects of ammonia oxidation at 70°C by thermophilic Thaumarchaeota populations composed almost entirely of "Candidatus Nitrosocaldus." The nitrogen isotope effect of ammonia oxidation varied with ambient pH (25‰ to 32‰) and strongly suggests the oxidation of ammonia, not ammonium. The ␦ 18 O value of nitrite produced from ammonia oxidation varied with the ␦ 18 O value of water in the medium but was lower than the isotopic equilibrium value in water. Because experiments have shown that the half-life of abiotic oxygen isotope exchange between nitrite and water is longer than 33 h at 70°C and pH >6.6, the rate of ammonia oxidation by thermophilic Thaumarchaeota could be estimated using ␦ 18 O NO2؊ in geothermal environments, where the biological nitrite turnover is likely faster than 33 h. This study extended the range of application of nitrite isotopes as a geochemical clock of the ammonia oxidation activity to high-temperature environments. IMPORTANCEBecause ammonia oxidation is generally the rate-limiting step in nitrification that regulates the balance of reduced and oxidized nitrogen pools in nature, it is important to understand the biological and environmental factors underlying the regulation of the rate of ammonia oxidation. The discovery of ammonia-oxidizing archaea (AOA) in marine and terrestrial environments has transformed the concept that ammonia oxidation is operated only by bacterial species, suggesting that AOA play a significant role in the global nitrogen cycle. However, the archaeal contribution to ammonia oxidation in the global biosphere is not yet completely understood. This study successfully identified key factors controlling nitrogen and oxygen isotopic ratios of nitrite produced from thermophilic Thaumarchaeota and elucidated the applicability and its limit of nitrite isotopes as a geochemical clock of ammonia oxidation rate in nature. Oxygen isotope analysis in this study also provided new biochemical information on archaeal ammonia oxidation.

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Section: Discussionmentioning

confidence: 99%

Nitrogen and Oxygen Isotope Effects of Ammonia Oxidation by Thermophilic Thaumarchaeota from a Geothermal Water Stream

Nishizawa

Sakai

Konno

et al. 2016

Appl Environ Microbiol

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“…At standard conditions, dissolved NH 4 + dissociates to NH 3 with a pKa of 9.25 (i.e. at pH 9.25, both species exist at equal abundances), and NH 3 can be lost by volatilization with a fractionation of -45‰ (Li et al, 2012). The residual heavy NH 4 + can be preserved in biomass.…”

Section: Nh 3 Volatilizationmentioning

confidence: 99%

The evolution of Earth's biogeochemical nitrogen cycle

Stüeken

Kipp

Koehler

et al. 2016

Earth-Science Reviews

312

287

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Nitrogen is an essential nutrient for all life on Earth and it acts as a major control on biological productivity in the modern ocean. Accurate reconstructions of the evolution of life over the course of the last four billion years therefore demand a better understanding of nitrogen bioavailability and speciation through time. The biogeochemical nitrogen cycle has evidently been closely tied to the redox state of the ocean and atmosphere. Multiple lines of evidence indicate that the Earth"s surface has passed in a non-linear fashion from an anoxic state in the Hadean to an oxic state in the later Phanerozoic. It is therefore likely that the nitrogen cycle has changed markedly over time, with potentially severe implications for the productivity and evolution of the biosphere. Here we compile nitrogen isotope data from the literature and review our current understanding of the evolution of the nitrogen cycle, with particular emphasis on the Precambrian. Combined with recent work on redox conditions, trace metal availability, sulfur and iron cycling on the early Earth, we then use the nitrogen isotope record as a platform to test existing and new hypotheses about biogeochemical pathways that may have controlled nitrogen availability through time. Among other things, we conclude that (a) abiotic nitrogen sources were likely insufficient to sustain a large biosphere, thus favoring an early origin of biological N 2 fixation, (b) evidence of nitrate in the Neoarchean and Paleoproterozoic confirm current views of increasing surface oxygen levels at those times, (c) abundant ferrous iron and sulfide in the midPrecambrian ocean may have affected the speciation and size of the fixed nitrogen reservoir, and (d) nitrate availability alone was not a major driver of eukaryotic evolution.

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“…Xiao and Liu (2002) reported the isotope enrichment factor (ε) was about +7.8‰ in summer in Guiyang. The ε was calculated to be +5.0‰ by Moore (1977), +7.6‰, +15.3‰, +15.7‰ by Urey (1947), Scalan (1958), Hanschmann (1981) and Li et al (2012). These indicated that 15 NH 3 was preferentially dissolved in rain by exchange reactions.…”

Section: Results Of Rayleigh Modelmentioning

confidence: 96%

“…Rain drops absorb atmospheric gaseous ammonia by three processes (Fig. S1): process 1 is diffusion, which shows kinetic effect because a greater diffusion velocity of lighter isotope is expected by the kinetic energy equation; process 2 tends to have NH 3(gas) /NH 3(aq) and NH 3(gas) /NH 4 + (aq) equilibrium, which has a ε value range between +20‰ and +27‰ in NH 3(gas) /NH 4 + (aq) equilibrium system and between +5‰ and 15.7‰ in NH 3(gas) /NH 3(aq) equilibrium system (Urey, 1947;Scalan, 1958;Moore, 1977;Hanschmann, 1981;Högberg, 1997;Tozer, 2006;Li et al, 2012). But the isotope fractionation in NH 3(gas) /NH 4 + (aq) equilibrium system is not important at less than pH 7 (Moore, 1977); and process 3 is ionization equilibrium and absorption process, which has small or negligible fractionation (Delwiche and Steyn, 1970;Högberg, 1997).…”

Section: Discussionmentioning

confidence: 99%

“…In general, the diffusion rates are faster than droplet removal rates and hence equilibrium must be established and the diffusion process should be relatively unimportant (Moore, 1977). The combined isotopic effect of these factors is often large (Moore, 1977;Urey, 1947;Scalan, 1958;Hanschmann, 1981;Högberg, 1997;Li et al, 2012). ε controlled by exchange reactions between gaseous NH 3 and NH 3 /NH 4 + in rainfall drops may be controlled by meteorological factors, such as temperature, relatively humidity and pH (Högberg, 1997;Li et al, 2012;Schoonen and Xu, 2001;Xiao et al, 2012), which affect the rate of gaseous-liquid equilibrium (Lewis and Whitman, 1924).…”

Section: Discussionmentioning

confidence: 99%

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