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Martocello DE, Wankel SD. Physiological Influence of Fe and Cu Availability on Nitrogen Isotope Fractionation during Ammonia Oxidation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:421-431. [PMID: 38147309 DOI: 10.1021/acs.est.3c05964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2023]
Abstract
Microbially mediated cycling processes play central roles in regulating the speciation and availability of nitrogen, a vital nutrient with wide implications for agriculture, water quality, wastewater treatment, ecosystem health, and climate change. Ammonia oxidation, the first and rate-limiting step of nitrification, is carried out by bacteria (AOB) and archaea (AOA) that require the trace metal micronutrients copper (Cu) and iron (Fe) for growth and metabolic catalysis. While stable isotope analyses for constraining nitrogen cycling are commonly used, it is unclear whether metal availability may modulate expression of stable isotope fractionation during ammonia oxidation, by varying growth or through regulation of metabolic metalloenzymes. We present the first study examining the influence of Fe and Cu availability on the kinetic nitrogen isotope effect in ammonia oxidation (15εAO). We report a general independence of 15εAO from the growth rate in AOB, except at a low temperature (10 °C). With AOA Nitrosopumilus maritimus SCM1, however, 15εAO decreases nonlinearly at lower oxidation rates. We examine assumptions involved in the interpretation of 15εAO values and suggest these dynamics may arise from physiological constraints that push the system toward isotopic equilibrium. These results suggest important links between isotope fractionation and environmental constraints on physiology in these key N cycling microorganisms.
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Affiliation(s)
- Donald E Martocello
- Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, United States
- Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, United States
| | - Scott D Wankel
- Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, United States
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Chen Y, Chen M, Chen J, Fan L, Zheng M, Qiu Y. Dual isotopes of nitrite in the Amundsen Sea in summer. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 843:157055. [PMID: 35780884 DOI: 10.1016/j.scitotenv.2022.157055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 06/25/2022] [Accepted: 06/25/2022] [Indexed: 06/15/2023]
Abstract
Nitrite (NO2-) is a key intermediate in the nitrogen (N) cycle, and its transformation is accomplished by microbial communities. However, due to few studies on the nitrite cycle, a clear assessment of the contribution to the marine biogeochemical cycle is missing. Here, we present data on nitrogen and oxygen isotopic composition of NO2- in the Amundsen Sea in summer, and explore the biogeochemical processes that influence the NO2- cycle. Extremely low δ15NNO2 and abnormally high δ18ONO2 were found in the upper waters of the Amundsen Sea, with δ15NNO2 as low as -58.4 ‰ and δ18ONO2 as high as 44.4 ‰. Enzymatic isotopic exchange reactions between nitrate and nitrite have been proposed to be responsible for these isotopic anomalies. The mirror-symmetrical variation between δ15NNO2 and δ18ONO2 suggests that the isotopic fractionation effects of nitrogen and oxygen are opposite in isotope exchange reactions. Dual isotopes of nitrite indicate that ammonia oxidation is the main source of nitrite, thus nitrification plays an important role in the formation of primary nitrite maximum in the upper Amundsen Sea. The nitrogen and oxygen isotopic compositions of nitrite provide support for clarifying multiple processes of marine nitrogen cycle.
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Affiliation(s)
- Yangjun Chen
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
| | - Min Chen
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China.
| | - Jinxu Chen
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
| | - Lingfang Fan
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
| | - Mingfang Zheng
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
| | - Yusheng Qiu
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
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Gruber W, Magyar PM, Mitrovic I, Zeyer K, Vogel M, von Känel L, Biolley L, Werner RA, Morgenroth E, Lehmann MF, Braun D, Joss A, Mohn J. Tracing N 2O formation in full-scale wastewater treatment with natural abundance isotopes indicates control by organic substrate and process settings. WATER RESEARCH X 2022; 15:100130. [PMID: 35287381 PMCID: PMC8917317 DOI: 10.1016/j.wroa.2022.100130] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 02/25/2022] [Accepted: 02/26/2022] [Indexed: 06/14/2023]
Abstract
Nitrous oxide (N2O) dominates greenhouse gas emissions in wastewater treatment plants (WWTPs). Formation of N2O occurs during biological nitrogen removal, involves multiple microbial pathways, and is typically very dynamic. Consequently, N2O mitigation strategies require an improved understanding of nitrogen transformation pathways and their modulating controls. Analyses of the nitrogen (N) and oxygen (O) isotopic composition of N2O and its substrates at natural abundance have been shown to provide valuable information on formation and reduction pathways in laboratory settings, but have rarely been applied to full-scale WWTPs. Here we show that N-species isotope ratio measurements at natural abundance level, combined with long-term N2O monitoring, allow identification of the N2O production pathways in a full-scale plug-flow WWTP (Hofen, Switzerland). Heterotrophic denitrification appears as the main N2O production pathway under all tested process conditions (0-2 mgO2/l, high and low loading conditions), while nitrifier denitrification was less important, and more variable. N2O production by hydroxylamine oxidation was not observed. Fractional N2O elimination by reduction to dinitrogen (N2) during anoxic conditions was clearly indicated by a concomitant increase in site preference, δ18O(N2O) and δ15N(N2O). N2O reduction increased with decreasing availability of dissolved inorganic N and organic substrates, which represents the link between diurnal N2O emission dynamics and organic substrate fluctuations. Consequently, dosing ammonium-rich reject water under low-organic-substrate conditions is unfavorable, as it is very likely to cause high net N2O emissions. Our results demonstrate that monitoring of the N2O isotopic composition holds a high potential to disentangle N2O formation mechanisms in engineered systems, such as full-scale WWTP. Our study serves as a starting point for advanced campaigns in the future combining isotopic technologies in WWTP with complementary approaches, such as mathematical modeling of N2O formation or microbial assays to develop efficient N2O mitigation strategies.
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Affiliation(s)
- Wenzel Gruber
- Eawag, Swiss Federal Institute for Aquatic Science and Technology, 8600 Dübendorf, Switzerland
| | - Paul M Magyar
- Department of Environmental Sciences, Aquatic and Isotope Biogeochemistry, University of Basel, Basel 4056, Switzerland
| | - Ivan Mitrovic
- Eawag, Swiss Federal Institute for Aquatic Science and Technology, 8600 Dübendorf, Switzerland
| | - Kerstin Zeyer
- Laboratory for Air Pollution / Environmental Technology, Empa, Dübendorf 8600, Switzerland
| | - Michael Vogel
- Department of Civil, Environmental and Geomatic Engineering, ETH, Zürich 8093, Switzerland
| | - Luzia von Känel
- Department of Civil, Environmental and Geomatic Engineering, ETH, Zürich 8093, Switzerland
| | - Lucien Biolley
- Department of Civil, Environmental and Geomatic Engineering, ETH, Zürich 8093, Switzerland
| | - Roland A Werner
- Department of Environmental Systems Science, ETH, Zürich 8092, Switzerland
| | - Eberhard Morgenroth
- Eawag, Swiss Federal Institute for Aquatic Science and Technology, 8600 Dübendorf, Switzerland
| | - Moritz F Lehmann
- Department of Environmental Sciences, Aquatic and Isotope Biogeochemistry, University of Basel, Basel 4056, Switzerland
| | - Daniel Braun
- Department of Civil, Environmental and Geomatic Engineering, ETH, Zürich 8093, Switzerland
| | - Adriano Joss
- Eawag, Swiss Federal Institute for Aquatic Science and Technology, 8600 Dübendorf, Switzerland
| | - Joachim Mohn
- Laboratory for Air Pollution / Environmental Technology, Empa, Dübendorf 8600, Switzerland
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Nitrogen isotope effects can be used to diagnose N transformations in wastewater anammox systems. Sci Rep 2021; 11:7850. [PMID: 33846510 PMCID: PMC8041819 DOI: 10.1038/s41598-021-87184-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 03/22/2021] [Indexed: 11/08/2022] Open
Abstract
Anaerobic ammonium oxidation (anammox) plays an important role in aquatic systems as a sink of bioavailable nitrogen (N), and in engineered processes by removing ammonium from wastewater. The isotope effects anammox imparts in the N isotope signatures (15N/14N) of ammonium, nitrite, and nitrate can be used to estimate its role in environmental settings, to describe physiological and ecological variations in the anammox process, and possibly to optimize anammox-based wastewater treatment. We measured the stable N-isotope composition of ammonium, nitrite, and nitrate in wastewater cultivations of anammox bacteria. We find that the N isotope enrichment factor 15ε for the reduction of nitrite to N2 is consistent across all experimental conditions (13.5‰ ± 3.7‰), suggesting it reflects the composition of the anammox bacteria community. Values of 15ε for the oxidation of nitrite to nitrate (inverse isotope effect, - 16 to - 43‰) and for the reduction of ammonium to N2 (normal isotope effect, 19-32‰) are more variable, and likely controlled by experimental conditions. We argue that the variations in the isotope effects can be tied to the metabolism and physiology of anammox bacteria, and that the broad range of isotope effects observed for anammox introduces complications for analyzing N-isotope mass balances in natural systems.
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Dai S, Wen T, Cai Z, Zhang J. Dynamics of nitrite in acidic soil during extraction with potassium chloride studied using 15 N tracing. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2020; 34:e8746. [PMID: 32092188 DOI: 10.1002/rcm.8746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 01/31/2020] [Accepted: 02/10/2020] [Indexed: 06/10/2023]
Abstract
RATIONALE Nitrite is well known to be unstable, including during soil extraction with KCl (especially in acidic soils), but the source and fate of NO2 - in the short duration of the extraction process remain unclear. METHODS A series of 15 N-tracing studies explored NO2 - transformations during KCl extraction in acidic and alkaline soils. Tests considering multiple factors assessed the interactions of such factors as soil sterilization, extraction time, and pH adjustment. After addition of 15 NO2 - , 15 NH4 + , and 15 NO3 - tracers, the concentrations and isotopic compositions of N2 O, N2 , NH4 + , NO3 - , NO2 - , and dissolved organic nitrogen (DON) were measured to investigate the production and consumption of NO2 - . RESULTS Nitrite was stable in alkaline soils during KCl extraction. In contrast, changes did occur in acidic soils during KCl extraction: NO2 - declined rapidly in the first 10 min of extraction although the subsequent rate of decrease lessened as the extraction time progressed. Significant dilution of 15 NO2 - suggested high rates of NO2 - production and even higher rates of consumption. The soil's organic N was the only source of NO2 - and also its main destination. Soil sterilization showed that NO2 - processes during extraction were chemical, not microbial. The pH adjustment of acidic soil stabilized its NO2 - . CONCLUSIONS Overall, the pH adjustment of KCl solution appears favorable for investigating NO2 - dynamics. For example, this work recommends an extraction solution comprising a 4:1 mixture of 2.5 M KCl solution and pH 8.4 buffer, which was more convenient to operate than the method reported by Stevens and Laughlin.
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Affiliation(s)
- Shenyan Dai
- School of Geography, Nanjing Normal University, Nanjing, 210023, China
- State Key Laboratory Cultivation Base of Geographical Environment Evolution, Nanjing, 210023, China
| | - Teng Wen
- School of Geography, Nanjing Normal University, Nanjing, 210023, China
- Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing, 210023, China
- Key Laboratory of Virtual Geographic Environment (Nanjing Normal University), Ministry of Education, Nanjing, 210023, China
| | - Zucong Cai
- School of Geography, Nanjing Normal University, Nanjing, 210023, China
- Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing, 210023, China
- Key Laboratory of Virtual Geographic Environment (Nanjing Normal University), Ministry of Education, Nanjing, 210023, China
| | - Jinbo Zhang
- School of Geography, Nanjing Normal University, Nanjing, 210023, China
- Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing, 210023, China
- Key Laboratory of Virtual Geographic Environment (Nanjing Normal University), Ministry of Education, Nanjing, 210023, China
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