Starting with the work of Ben Houlton, we have collaborated with the group of Lars Hedin in the Department of Ecology and Evolutionary Biology in isotope studies of terrestrial N cycling. We have also worked on the nitrate N and O isotopes in rain, snow, and ice as tracers of reactive nitrogen sources and processing in the modern and ancient atmosphere.
References
9 Publications
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Erratum: Global nitrogen cycle: Critical enzymes, organisms, and processes for nitrogen budgets and dynamics (Chemical Reviews (2020) 120:12 (5308-5351) DOI: 10.1021/acs.chemrev.9b00613)
(Figure Presented) Figure 4. Cycle of biologically driven N transformations that occur in natural and human-influenced terrestrial and marine environments. Nitrogen (N2) fixation (step 1) and N assimilation (from ammonium, nitrate, or organic N, step 2) are anabolic processes, whereas mineralization (step 3), nitrification (steps 4−6), DNRA (steps 7,…
Global Nitrogen Cycle: Critical Enzymes, Organisms, and Processes for Nitrogen Budgets and Dynamics
Nitrogen (N) is used in many of life s fundamental biomolecules, and it is also a participant in environmental redox chemistry. Biogeochemical processes control the amount and form of N available to organisms ("fixed"N). These interacting processes result in N acting as the proximate limiting nutrient in most surface environments. Here, we review…
Nitrogen isotope fractionation by alternative nitrogenases and past ocean anoxia
Biological nitrogen fixation constitutes the main input of fixed nitrogen to Earth s ecosystems, and its isotope effect is a key parameter in isotope-based interpretations of the N cycle. The nitrogen isotopic composition (δ15N) of newly fixed N is currently believed to be∼-10/00, based on measurements of organic matter from diazotrophs using…
Analysis of nitric oxide isotopes via differential faraday rotation spectroscopy
We present real-time optical polarization subtraction for calibration of Faraday rotation spectra. Noise analysis yields minor isotope sensitivity of 3.0 ppbv·Hz-1/2 and 1.7×10-8 rad·Hz-1/2 noise-equivalent angle. Sub-permil ratiometric precision is achieved at integration times >100 s. © 2016 OSA.
Isotopic ratiometry of nitric oxide using a dual-modulation faraday rotation spectrometer
A dual-modulation Faraday rotation spectrometer is employed for isotopic ratiometry of nitric oxide (NO) converted from nitrate/nitrite. Excellent linearity of measured NO to dissolved nitrate is demonstrated. Ratiometry of IAEA-NO-3 standards indicates 3 % accuracy. © 2014 OSA.
Isotopic ratiometry of nitric oxide using a dual-modulation faraday rotation spectrometer
A dual-modulation Faraday rotation spectrometer is employed for isotopic ratiometry of nitric oxide (NO) converted from nitrate/nitrite. Excellent linearity of measured NO to dissolved nitrate is demonstrated. Ratiometry of IAEA-NO-3 standards indicates ∼3 % accuracy. © 2014 Optical Society of America.
Dissolved Organic Nitrogen Cycling in the South China Sea From an Isotopic Perspective
Dissolved organic nitrogen (DON) is the dominant form of fixed nitrogen in most low and middle latitude ocean surface waters. Here, we report measurements of DON isotopic composition (δ15N) from the west South China Sea (SCS), with the goal of providing new insight into DON cycling. The concentration of DON in the surface ocean is correlated (r =…
Nitric oxide isotopic analyzer based on a compact dual-modulation faraday rotation spectrometer
We have developed a transportable spectroscopic nitrogen isotopic analyzer. The spectrometer is based on dual-modulation Faraday rotation spectroscopy of nitric oxide isotopologues with near shot-noise limited performance and baseline-free operation. Noise analysis indicates minor isotope (15NO) detection sensitivity of 0.36 ppbv·Hz−1/2,…
In-line optical subtraction using a differential Faraday rotation spectrometer for 15NO/14NO isotopic analysis
We present a dual-modulation Faraday rotation spectrometer with in-line optical subtraction for differential measurement of nitric oxide (NO) isotopologues. In-situ sample referencing is accomplished via differential dual-cell measurements, with 3.1 ppbv/rt(Hz) (15NO) sensitivity through 15 cm optical path length. Our system operates at 1.9x…