<div><p><strong>Sampling and Analytical Procedures:</strong><br />
Duplicate water column samples were collected by Niskin or GoFlo rosette on one of the following types of casts:</p>
<p>'CTD',<br />
'TMC' (Trace Metal Clean), or<br />
'TWO' (small classical CTD with 12 x Niskin bottles) cast.</p>
<p>Nitrogen isotopic analysis (d15N of NO3-+NO2-) 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).</p>
<p>Briefly, NO3-+NO2- was quantitatively reduced to N2O by <em>Pseudomonas aureofaciens</em>, 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 nanomoles N2O, which was then purged from the vial using a helium carrier gas. The d15N of N2O in samples was calibrated with international isotopic reference materials.</p>
<p><strong>Calibration:</strong><br />
NO3-+NO2- d15N analyses were calibrated with IAEA N3 and USGS 34 NO3- d15N isotopic reference materials as described in McIlvin and Casciotti, 2011.</p>
<p><strong>Precision:</strong><br />
The average precision of NO3-+NO2- d15N measurements was <u><</u>0.2 per mil.</p></div>
TONGA NO3 d15N
TONGA nitrate plus nitrite isotopes
<div><p><strong>BCO-DMO Processing:<br />
Version 1:</strong><br />
- Added a column for Vessel<br />
- Combined date and time columns to format of yyyy-mm-dd hh:mm:ss<br />
- Modified parameter (column) names to conform with BCO-DMO naming conventions. The only allowed characters are A-Z,a-z,0-9, and underscores. No spaces, hyphens, commas, parentheses, or Greek letters.</p>
<p><strong>Version 2:</strong><br />
- Created ISO 8601 date-time field;<br />
- Renamed fields to comply with BCO-DMO naming conventions.</p>
<p><strong>Version History:</strong><br />
- version 1 (date 2022-02-24) - contains only data from 2019 cruise.<br />
- version 2 (date 2023-04-03) - contains data from 2019 and 2020 cruises.</p></div>
869963
TONGA nitrate plus nitrite isotopes
2022-02-18T15:32:28-05:00
2022-02-18T15:32:28-05:00
2023-04-04T15:13:46-04:00
urn:bcodmo:dataset:869963
Water column nitrate plus nitrite d15N measurements from seawater collected in November 2019 and November 2020 in the Western Tropical South Pacific
Here we present nitrate plus nitrite isotopic data from the TONGA research cruises to the Western Tropical South Pacific in 2019 and a reoccupation in 2020. These data were collected along a transect focusing on the impacts on biological productivity and the biological carbon pump from shallow hydrothermal sources of trace elements. Notably, these data show that the subsurface nitrate plus nitrite isotopes were low, 2 to 3 per mil, in the vicinity of the hydrothermal vents. While subsurface nitrate plus nitrite isotopes were low higher, 4 to 7 per mil, at stations further from the vents.
false
Knapp, A. N., Forrer, H. J. (2023) Water column nitrate plus nitrite d15N measurements from seawater collected in November 2019 and November 2020 in the Western Tropical South Pacific. Biological and Chemical Oceanography Data Management Office (BCO-DMO). (Version 2) Version Date 2023-04-03 [if applicable, indicate subset used]. doi:10.26008/1912/bco-dmo.869963.2 [access date]
true
2
10.26008/1912/bco-dmo.869963.2
false
Nitrate d15N
d15N budget
nitrogen fixation
Western Tropical South Pacific
NO3 d15N
N2 fixation
2023-04-03
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869963
http://lod.bco-dmo.org/id/dataset/869963
2019-11-05 - 2020-11-04
2019-11-05
2019-11-05
---05
308
--11
2019
2020-11-04
2020-11-04
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OSPREY
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