Isotopic evidence for seasonality of microbial internal nitrogen cycles in a temperate forested catchment with heavy snowfall

Hattori, Shohei; Palma, Yoshio Nuñez; Itoh, Yuko; Kawasaki, Moeko; Fujihara, Yoichi; Takase, Keiji; Yoshida, Naohiro

doi:10.1016/j.scitotenv.2019.06.507

Cited by 25 publications

(34 citation statements)

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“…Although the NFARM intact core direct measurements are an improvement of previous methods involving inhibitors or disturbed soils (Groffman et al., 2006), there are concerns about the disturbance of plant:soil interactions, and holding times with this method (Wang, Pan, et al., 2020). There will be a strong need for independent evaluation of denitrification estimates produced from sensors and models, either with detailed mass balances or future development of alternative time and area‐integrated methods, perhaps with flux towers and/or isotopes (Hattori et al., 2019; Yu et al., 2019).…”

Section: Discussionmentioning

confidence: 99%

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Drivers of Hot Spots and Hot Moments of Denitrification in Agricultural Systems

et al. 2021

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Section: Discussionmentioning

confidence: 99%

“…There will be a strong need for independent evaluation of denitrification estimates produced from sensors and models, either with detailed mass balances or future development of alternative time and area-integrated methods, perhaps with flux towers and/or isotopes (Hattori et al, 2019;Yu et al, 2019).…”

Section: Discussionmentioning

confidence: 99%

Drivers of Hot Spots and Hot Moments of Denitrification in Agricultural Systems

et al. 2021

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“…However, a negative relationship (r = −0.99, n = 3) is found in our water samples (Table 1). We further estimate δ 15 N and δ 18 O values of nonatmospheric nitrate following the isotopic mass balance of Hattori et al (2019), which is similar to the estimation for Δ 17 O outlined above:…”

Section: 1029/2019jd031878mentioning

confidence: 99%

A Complete Isotope (δ¹⁵N, δ¹⁸O, Δ¹⁷O) Investigation of Atmospherically Deposited Nitrate in Glacial‐Hydrologic Systems Across the Third Pole Region

et al. 2020

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The Himalayas and Tibetan Plateau, identified as the Third Pole (TP), is a unique region because of its insertion into global environmental and climatic changes. Deposition of atmospheric nitrate in this region is one of the most important sources of reactive nitrogen to glacial-hydrologic system and ecosystems. The isotopic composition of atmospherically deposited nitrate preserved in ice bodies plays a central role in delineating environmental and climatic changes, present, and past. Here, we provide an overview of the complete isotopic compositions (δ 15 N, δ 18 O, and Δ 17 O) of nitrate in aerosol, snow, ice, and water samples (n = 46) collected across the Southern, Southeastern, Central, and Northern TP to constrain complex nitrogen cycles of the atmosphere, cryosphere, hydrosphere, and, potentially, the biosphere. A large variability of snow nitrate isotopic compositions is observed across the TP at different spatial scales (from a single glacier to the entire plateau), likely due to the complex landscape and relevant physical and chemical processes across the TP. Large nitrate Δ 17 O values are observed in water samples collected from the Mt. Everest region, highlighting the considerable fraction (up to 45%) of atmospheric nitrate to the nitrate load in this Himalayan hydrologic system. Our work reveals the complex chemical, depositional, and postdepositional processes over the TP that are greater than previously thought and identifies further comprehensive investigations, which entail using nitrate isotopic compositions as an identifier for nitrate source apportionment in various ecosystems and understanding past atmospheric and climatic conditions in this region. The Himalayas and Tibetan Plateau hosts the largest number of glaciers (>36,000) on the planet outside of polar regions with thousands of lakes and is referred to as the Third Pole (TP) (Yao et al., 2012). This massive water reservoir within this pristine region sustains the water supply and food security for billions of people in ©2020. American Geophysical Union. All Rights Reserved.

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“…2b), from −1.9 ‰ to +7.7 ‰ for δ 18 O (Fig. and 2d), the values are typical for stream nitrate eluted from temperate forested catchments (Hattori et al, 2019;Huang et al, 2020;Nakagawa et al, 2013Nakagawa et al, , 2018Riha et al, 2014;Sabo et al, 2016;Tsunogai et al, 2014Tsunogai et al, , 2016. On the other hand, the data recorded on 2019/1/31 exceeded the 2σ variation range of the whole δ 18 O and Δ 17 O data.…”

Section: Variation During the Routine Observationmentioning

confidence: 77%

Tracing the source of nitrate enriched in a forested stream during storm events

Ding

Tsunogai

Nakagawa

et al. 2022

Preprint

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Abstract. To clarify the source of nitrate increased during storm events in temperate forested streams, we monitored temporal variation in the concentrations and stable isotopic compositions including Δ17O of stream nitrate in a forested catchment (KJ catchment, Japan) during three storm events I, II, and III. The stream showed significant temporal variation in nitrate concentration, from 24.7 µM to 122.6 µM, from 28.7 µM to 134.1 µM, and from 46.6 µM to 114.5 µM during the storm events I, II, and III, respectively. On the other hand, the isotopic compositions (δ15N, δ18O, and Δ17O) of stream nitrate showed a decrease in accordance with the increase in the stream nitrate concentration, from +2.5 ‰ to −0.1 ‰, from +3.0 ‰ to −0.5 ‰, and from +3.5 ‰ to −0.1 ‰ for δ15N, from +3.1 ‰ to −3.4 ‰, from +2.9 ‰ to −2.5 ‰, and from +2.1 ‰ to −2.3 ‰ for δ18O, and from +1.6 ‰ to +0.3 ‰, from +1.4 ‰ to +0.3 ‰, and from +1.2 ‰ to +0.5 ‰ for Δ17O during the storm events I, II, and III, respectively. Besides, we found strong linear relationships between the isotopic compositions (δ15N, δ18O, and Δ17O) of stream nitrate and the reciprocal of stream nitrate concentrations during each storm event, implying that the temporal variation in the stream nitrate can be explained by simple mixing between two distinctive endmembers of nitrate having different isotopic compositions. Furthermore, we found that both concentrations and the isotopic compositions of soil nitrate obtained in the riparian zone of the stream were plotted on the nitrate-enriched extension of the linear relationship. We conclude that the soil nitrate in the riparian zone was responsible for the increase in stream nitrate during the storm events. In addition, we found that the concentration of unprocessed atmospheric nitrate in the stream was stable at 1.6 ± 0.4 µM, 1.8 ± 0.4 µM, and 2.1 ± 0.4 µM during the storm events I, II, and III, respectively, irrespective to the significant variations in the total nitrate concentration. We conclude that the storm events have little impacts on the concentration of unprocessed atmospheric nitrate in the stream and thus the annual export flux of unprocessed atmospheric nitrate relative to the annual deposition flux can be a robust index to evaluate nitrogen saturation in forested catchments, irrespective to the variation in the number of storm events and/or the variation in the elapsed time from storm events to sampling.

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Isotopic evidence for seasonality of microbial internal nitrogen cycles in a temperate forested catchment with heavy snowfall

Cited by 25 publications

References 50 publications

Drivers of Hot Spots and Hot Moments of Denitrification in Agricultural Systems

Drivers of Hot Spots and Hot Moments of Denitrification in Agricultural Systems

A Complete Isotope (δ¹⁵N, δ¹⁸O, Δ¹⁷O) Investigation of Atmospherically Deposited Nitrate in Glacial‐Hydrologic Systems Across the Third Pole Region

Tracing the source of nitrate enriched in a forested stream during storm events

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Isotopic evidence for seasonality of microbial internal nitrogen cycles in a temperate forested catchment with heavy snowfall

Cited by 25 publications

References 50 publications

Drivers of Hot Spots and Hot Moments of Denitrification in Agricultural Systems

Drivers of Hot Spots and Hot Moments of Denitrification in Agricultural Systems

A Complete Isotope (δ15N, δ18O, Δ17O) Investigation of Atmospherically Deposited Nitrate in Glacial‐Hydrologic Systems Across the Third Pole Region

Tracing the source of nitrate enriched in a forested stream during storm events

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A Complete Isotope (δ¹⁵N, δ¹⁸O, Δ¹⁷O) Investigation of Atmospherically Deposited Nitrate in Glacial‐Hydrologic Systems Across the Third Pole Region