<div><p>NO3-+NO2- d15N analysis was by the “denitrifier method” and followed the methods described by Sigman et al., 2001, Casciotti et al., 2002, McIlvin and Casciotti, 2011, and Weigand et al., 2016. Briefly, NO3-+NO2- was quantitatively reduced to N2O by Pseudomonas aureofaciens and Pseudomonas chlororaphis, which was then cryogenically focused and analyzed on an isotope ratio mass spectrometer. A volume of sample was added to each bacterial vial to achieve a final quantity of 10 or 20 nmols N2O, which was then purged from the vial using a helium carrier gas. The d15N of N2O in samples was calibrated with the international isotopic reference materials described in the Processing Description.</p></div>
Water column nitrate+nitrite d15N measurements
<div><p>This data set includes water column nitrate+nitrite d15N measurements. These measurements were used together with measurements of the d15N of particulate nitrogen collected in floating sediment traps that were deployed for several days to calculate the relative contribution of subsurface nitrate and nitrogen from N2 fixation for supporting export production (“d15N budgets”). The results suggest that N2 fixation supported a majority of export at Long Duration (LD) stations A and B, and a minor fraction of export at LD C. The results at LD stations A and B are unique compared to other d15N budgets from the oligotrophic regions, whereas the results from LD C are similar to prior reports from the eastern tropical South Pacific as well as the North Pacific near Hawaii. Additionally, these data are compared with other metrics of N2 fixation made on the same cruise. </p></div>
OUTPACE - water column nitrate+nitrite
<div><p>Nitrate+nitrite concentration was measured by others using colorimetric methods, and can be found at:<br /><a href="http://www.obs-vlfr.fr/proof/php/outpace/outpace.php">http://www.obs-vlfr.fr/proof/php/outpace/outpace.php</a></p>
<p>The average precision of nitrate+nitrite d15N measurements was <0.2 per mil, but with the standard deviation for duplicate analyses of each sample reported here. Samples were calibrated with IAEA N3 and USGS 34 NO3- d15N isotopic reference materials as described in McIlvin and Casciotti, 2011. </p>
<p><strong>BCO-DMO Processing Notes:</strong></p>
<ul><li>added conventional header with dataset name, PI name, version date.</li>
<li>modified parameter names to conform with BCO-DMO naming conventions.</li>
<li>re-formatted date from dd Month yyyy (day month year) to yyyymmdd.</li>
<li>appended date, latitude, and longitude to each data entry.</li>
<li>If an observation did not exist, 'nd' (no data) was inserted. </li>
</ul></div>
733237
OUTPACE - water column nitrate+nitrite
2018-04-11T15:49:07-04:00
2018-04-11T15:49:07-04:00
2023-07-07T16:10:26-04:00
urn:bcodmo:dataset:733237
Water column nitrate+nitrite d15N measurements from R/V L'Atalante in the southwest Pacific Ocean between New Caledonia and Tahiti from February to March 2015
Constraining the rates and spatial distribution of di-nitrogen (N2) fixation fluxes to the ocean informs our understanding of the environmental sensitivities of N2 fixation as well as the timescale over which the fluxes of nitrogen (N) to and from the ocean may respond to each other. Here we quantify rates of N2 fixation as well as its contribution to export production along a zonal transect in the Western Tropical South Pacific (WTSP) Ocean using N isotope (“d15N”) budgets. Comparing measurements of water column nitrate+nitrite d15N with the d15N of sinking particulate N at a western, central, and eastern station, these d15N budgets indicate high, modest, and low rates of N2 fixation at the respective stations. The results also imply that N2 fixation supports exceptionally high, i.e., >50%, of export production at the western and central stations, which are also proximal to the largest iron sources. These geochemically-based rates of N2 fixation are equal to or greater than those previously reported in the tropical North Atlantic, indicating that the WTSP Ocean has the capacity to support globally significant rates of N2 fixation, which may compensate for N removal in the oxygen deficient zones of the eastern tropical Pacific.
false
Knapp, A., McCabe, K., Grosso, O., Leblond, N., Moutin, T., Bonnet, S. (2018) Water column nitrate+nitrite d15N measurements from R/V L'Atalante in the southwest Pacific Ocean between New Caledonia and Tahiti from February to March 2015. Biological and Chemical Oceanography Data Management Office (BCO-DMO). (Version 2018-04-11) Version Date 2018-04-11 [if applicable, indicate subset used]. doi:10.1575/1912/bco-dmo.733303 [access date]
true
2018-04-11
10.1575/1912/bco-dmo.733303
false
nitrogen
Nitrate d15N
d15N budget
southwest Pacific
nitrogen fixation
2018-04-11
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