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Dempsey, Britton; Kam, Kitty; Rondón, Anadiuska N; Wallace, Douglas WR; Buchwald, Carolyn (2026): Nitrate concentration and nitrate stable isotopic signatures in seawater in the Labrador Sea in spring 2022 [dataset]. PANGAEA, https://doi.org/10.1594/PANGAEA.986850

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Published: 2026-02-12 • DOI registered: 2026-02-13

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Abstract:
Seawater was collected for nitrate concentration and stable isotopic analyses between May 20th and May 25th, 2022 aboard RV Celtic Explorer in an area between 58 - 59 degrees N and 49 - 50 degrees W. Nitrate concentration samples were collected from the Niskin unfiltered into 15ml centrifuge tubes and immediately frozen at -20 degrees C. After the survey, these samples were then thawed to room temperature and analyzed using standard colorimetric protocols coupled with a continuous flow nutrient analyzer at the Canada Excellence Research Chairs (CERC) laboratory at Dalhousie University. Sampling for nitrate stable isotopic measurements was conducted by filtering seawater directly from the Niskin-rosette using 0.22 µm polyethersulfone (PES) syringe filters (VWR Cat. no. 76479-018) and collected into 60 mL HDPE bottles, which were then immediately frozen upright at -20 degrees C. Isotopic analyses were prepared in duplicate using the denitrifier method (McIlvin and Casciotti, 2011; doi:10.1021/ac1028984), and analyzed using isotope ratio mass spectrometery (IRMS) on a Thermo Delta V located in the Canada Excellence Research Chairs (CERC) laboratory at Dalhousie University. Samples with detectable nitrite (>0.1 µmol/l) concentrations were first treated with sulfamic acid to remove potential interference on the 15N-NO3 pool as the denitrifier method does not discriminate between nitrate or nitrite (Granger and Sigman, 2009; doi:10.1002/rcm.4307). Isotopic analyses were referenced against USGS32, USGS34, and IAEA-NO3 reference materials.
Keyword(s):
Labrador Sea; nitrate concentration in sea water; stable nitrogen isotope (δ15N)
References:
Granger, Julie; Sigman, Daniel M (2009): Removal of nitrite with sulfamic acid for nitrate N and O isotope analysis with the denitrifier method. Rapid Communications in Mass Spectrometry, 23(23), 3753-3762, https://doi.org/10.1002/rcm.4307
McIlvin, Matthew R; Casciotti, Karen L (2011): Technical Updates to the Bacterial Method for Nitrate Isotopic Analyses. Analytical Chemistry, 83(5), 1850-1856, https://doi.org/10.1021/ac1028984
Funding:
Natural Sciences and Engineering Research Council (NSERC), grant/award no. NWA-BCP: The Northwest Atlantic Biological Carbon Pump
Ocean Frontier Institute, grant/award no. NWA-BCP: The Northwest Atlantic Biological Carbon Pump
Coverage:
Median Latitude: 58.677783 * Median Longitude: -49.290600 * South-bound Latitude: 58.483300 * West-bound Longitude: -49.610100 * North-bound Latitude: 58.816700 * East-bound Longitude: -49.110000
Date/Time Start: 2022-05-20T16:47:00 * Date/Time End: 2022-05-25T14:15:00
Minimum DEPTH, water: 5 m * Maximum DEPTH, water: 2000 m
Event(s):
CE22009_4_Day (CTD_cast_8)  * Latitude: 58.816700 * Longitude: -49.110000 * Date/Time: 2022-05-20T16:47:00 * Location: Labrador Sea * Campaign: CE22009 (BELAS-1) * Basis: Celtic Explorer * Method/Device: CTD/Rosette (CTD-RO)
CE22009_6_Day (CTD_cast_11)  * Latitude: 58.816700 * Longitude: -49.443400 * Date/Time: 2022-05-21T16:28:00 * Location: Labrador Sea * Campaign: CE22009 (BELAS-1) * Basis: Celtic Explorer * Method/Device: CTD/Rosette (CTD-RO)
CE22009_8_Day (CTD_cast_17)  * Latitude: 58.650000 * Longitude: -49.610100 * Date/Time: 2022-05-23T12:14:00 * Location: Labrador Sea * Campaign: CE22009 (BELAS-1) * Basis: Celtic Explorer * Method/Device: CTD/Rosette (CTD-RO)
Parameter(s):
#NameShort NameUnitPrincipal InvestigatorMethod/DeviceComment
1 Event labelEventBuchwald, Carolyn
2 Latitude of eventLatitudeBuchwald, Carolyn
3 Longitude of eventLongitudeBuchwald, Carolyn
4 Date/Time of eventDate/TimeBuchwald, Carolyn
5 DEPTH, waterDepth watermBuchwald, CarolynGeocode
6 Nitrate[NO3]-µmol/lWallace, Douglas WRAutomated wet chemistry analyzer, SKALAR, SAN++
7 δ15N, nitrateδ15N NO3‰ airBuchwald, CarolynDenitrifier method (McIlvin and Casciotti, 2011); measured with an isotope ratio mass spectrometer (IRMS), Thermo delta VVs. 15N of N2 in air
8 δ15N, nitrate, standard deviationδ15N NO3 std dev±Buchwald, CarolynDenitrifier method (McIlvin and Casciotti, 2011); measured with an isotope ratio mass spectrometer (IRMS), Thermo delta VVs. 15N of N2 in air
9 δ18O, nitrateδ18O NO3‰Buchwald, CarolynDenitrifier method (McIlvin and Casciotti, 2011); measured with an isotope ratio mass spectrometer (IRMS), Thermo delta VVs. 18O of Vienna standard mean ocean water (VSMOW)
10 δ18O, nitrate, standard deviationδ18O NO3 std dev±Buchwald, CarolynDenitrifier method (McIlvin and Casciotti, 2011); measured with an isotope ratio mass spectrometer (IRMS), Thermo delta VVs. 18O of Vienna standard mean ocean water (VSMOW)
License:
Creative Commons Attribution 4.0 International (CC-BY-4.0)
Status:
Curation Level: Enhanced curation (CurationLevelC)
Size:
345 data points

Data

Download dataset as tab-delimited text — use the following character encoding:

1 
Event		2 
Latitude		3 
Longitude		4 
Date/Time		5 
Depth water [m]		6 
[NO3]- [µmol/l]		7 
δ15N NO3 [‰ air]		8 
δ15N NO3 std dev [±]		9 
δ18O NO3 [‰]		10 
δ18O NO3 std dev [±]
CE22009_4_Day 58.8167-49.11002022-05-20T16:47252.229.910.038.130.09
CE22009_4_Day58.8167-49.11002022-05-20T16:47504.268.110.036.400.23
CE22009_4_Day58.8167-49.11002022-05-20T16:479012.215.530.092.790.07
CE22009_4_Day58.8167-49.11002022-05-20T16:4711013.165.150.082.900.07
CE22009_4_Day58.8167-49.11002022-05-20T16:4711013.165.020.122.590.04
CE22009_4_Day58.8167-49.11002022-05-20T16:4713013.884.780.122.430.26
CE22009_4_Day58.8167-49.11002022-05-20T16:4715014.364.810.022.230.03
CE22009_4_Day58.8167-49.11002022-05-20T16:4720014.774.780.052.240.04
CE22009_4_Day58.8167-49.11002022-05-20T16:4725014.614.750.002.470.29
CE22009_4_Day58.8167-49.11002022-05-20T16:4730014.984.780.061.970.40
CE22009_4_Day58.8167-49.11002022-05-20T16:4735015.204.720.102.230.16
CE22009_4_Day58.8167-49.11002022-05-20T16:4740015.134.840.082.230.16
CE22009_4_Day58.8167-49.11002022-05-20T16:4750015.594.790.052.000.12
CE22009_4_Day58.8167-49.11002022-05-20T16:47100015.924.790.021.890.03
CE22009_4_Day58.8167-49.11002022-05-20T16:47150016.064.620.071.810.04
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CE22009_6_Day58.8167-49.44342022-05-21T16:2812513.574.730.042.350.01
CE22009_9_Day 58.6500-49.36012022-05-22T12:2852.868.750.046.920.11
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CE22009_9_Day58.6500-49.36012022-05-22T12:2835015.324.670.142.110.00
CE22009_9_Day58.6500-49.36012022-05-22T12:2840015.024.470.042.040.00
CE22009_9_Day58.6500-49.36012022-05-22T12:2850014.964.490.012.050.00
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CE22009_9_Day58.6500-49.36012022-05-22T12:28200015.894.710.392.020.33
CE22009_8_Day 58.6500-49.61012022-05-23T12:148012.065.420.022.490.02
CE22009_8_Day58.6500-49.61012022-05-23T12:1410013.215.050.062.820.02
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CE22009_8_Day58.6500-49.61012022-05-23T12:1415014.424.770.052.090.11
CE22009_8_Day58.6500-49.61012022-05-23T12:1415014.614.850.072.180.01
CE22009_8_Day58.6500-49.61012022-05-23T12:1420014.964.740.142.270.12
CE22009_8_Day58.6500-49.61012022-05-23T12:1425015.454.550.142.200.21
CE22009_8_Day58.6500-49.61012022-05-23T12:1435015.134.840.112.140.03
CE22009_8_Day58.6500-49.61012022-05-23T12:1440015.154.610.041.830.36
CE22009_8_Day58.6500-49.61012022-05-23T12:14100016.094.760.142.030.02
CE22009_8_Day58.6500-49.61012022-05-23T12:14150016.114.710.091.820.07
CE22009_8_Day58.6500-49.61012022-05-23T12:14200016.234.640.081.790.14
CE22009_11_Day 58.6500-49.11002022-05-24T11:4052.909.260.126.590.38
CE22009_11_Day58.6500-49.11002022-05-24T11:40152.839.380.017.270.09
CE22009_11_Day58.6500-49.11002022-05-24T11:40252.999.240.058.540.14
CE22009_11_Day58.6500-49.11002022-05-24T11:4012014.234.940.152.600.31
CE22009_11_Day58.6500-49.11002022-05-24T11:4015014.644.950.082.460.12
CE22009_11_Day58.6500-49.11002022-05-24T11:4018014.724.980.042.440.15
CE22009_11_Day58.6500-49.11002022-05-24T11:4020014.824.820.132.580.14
CE22009_11_Day58.6500-49.11002022-05-24T11:40100015.584.850.191.920.19
CE22009_11_Day58.6500-49.11002022-05-24T11:40150015.704.600.212.160.15
CE22009_11_Day58.6500-49.11002022-05-24T11:40200015.944.690.112.250.23
CE22009_12_Day 58.4833-49.11002022-05-25T14:1552.359.020.037.380.08
CE22009_12_Day58.4833-49.11002022-05-25T14:15302.839.060.067.380.11
CE22009_12_Day58.4833-49.11002022-05-25T14:15708.236.360.084.200.03
CE22009_12_Day58.4833-49.11002022-05-25T14:1510513.485.090.012.270.09
CE22009_12_Day58.4833-49.11002022-05-25T14:1512514.474.930.122.170.06
CE22009_12_Day58.4833-49.11002022-05-25T14:1518015.834.800.112.160.03
CE22009_12_Day58.4833-49.11002022-05-25T14:1520015.404.880.002.110.10
CE22009_12_Day58.4833-49.11002022-05-25T14:1525015.834.660.312.040.01
CE22009_12_Day58.4833-49.11002022-05-25T14:1535016.034.840.041.970.09
CE22009_12_Day58.4833-49.11002022-05-25T14:1540015.874.740.232.120.01
CE22009_12_Day58.4833-49.11002022-05-25T14:1550015.854.820.071.990.04
CE22009_12_Day58.4833-49.11002022-05-25T14:15100016.274.740.111.940.11
CE22009_12_Day58.4833-49.11002022-05-25T14:15150016.454.620.262.070.25
CE22009_12_Day58.4833-49.11002022-05-25T14:15200016.464.810.011.890.03