What question did this study set out to answer?

To develop and validate a bacterial denitrification method for measuring the oxygen isotopic composition (18O/16O) of nitrate in both seawater and freshwater.

September 7, 2002Analytical Chemistry

Measurement of the Oxygen Isotopic Composition of Nitrate in Seawater and Freshwater Using the Denitrifier Method

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Authors

KCKaren L. CasciottiStanford University DSDaniel M. SigmanUniversity of Massachusetts Dartmouth MHMeredith G. HastingsPlanetary Science Institute

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Implication

Experimental study demonstrates accurate measurement of nitrate oxygen isotopes in seawater, highlighting a high-sensitivity bacterial method with minimal water exchange.

Key Points

To develop and validate a bacterial denitrification method for measuring the oxygen isotopic composition (18O/16O) of nitrate in both seawater and freshwater.
Converted dissolved nitrate samples into nitrous oxide (N2O) gas using cultured denitrifying bacteria (Pseudomonas aureofaciens).
Tested oxygen atom exchange during the conversion process using 18O-labeled water and evaluated oxygen isotopic fractionation.
Calibrated measured 18O/16O ratios using isotopic reference materials to correct for batch-specific fractionation and exchange effects.
Oxygen atom exchange with water contributed less than 10%, and frequently less than 3%, of oxygen atoms in the N2O analyte.
Oxygen isotope fractionation and oxygen exchange remained consistent within analytical batches, allowing successful correction using standard reference materials.
Achieved detection sensitivity down to 10 nmol and 1 µM nitrate with no interference from other dissolved solutes.

Cite This Study

Casciotti et al. (2002) studied this question.

synapsesocial.com/papers/69dab427615cc0c8eaa3d081 https://doi.org/10.1021/ac020113w

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Implication

Experimental study demonstrates accurate measurement of nitrate oxygen isotopes in seawater, highlighting a high-sensitivity bacterial method with minimal water exchange.

Measurement of the Oxygen Isotopic Composition of Nitrate in Seawater and Freshwater Using the Denitrifier Method

Discussion

Member takes

Implication

Key Points

Cite This Study

Measurement of the Oxygen Isotopic Composition of Nitrate in Seawater and Freshwater Using the Denitrifier Method

Discussion

Member takes

Implication

Key Points

Cite This Study

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