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OAS accession Detail for 0277949
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| accessions_id: | 0277949 | archive |
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| Title: | Nitrate+nitrite and nitrate-only d15N from R/V S.A. Agulhas II cruises VOY016 and VOY019 in the Southern Ocean south of Africa during 2015-2016 (NCEI Accession 0277949) |
| Abstract: | This dataset contains biological, chemical, optical, and physical data collected on R/V S.A. Agulhas II during cruises VOY016 and VOY019 in the Indian Ocean and South Atlantic Ocean from 2015-07-26 to 2016-05-09. These data include Nitrate, dN15_NO3, density, depth, dissolved Oxygen, fluorescence, mixed layer depth, nitrate plus nitrite, salinity calculated from CTD primary sensors, water pressure, and water temperature. The instruments used to collect these data include CTD Sea-Bird, Isotope-ratio Mass Spectrometer, and Niskin bottle. These data were collected by Daniel M. Sigman of Princeton University as part of the "Understanding the nitrogen isotopes of planktonic foraminifera: A modern Sargasso Sea study (N Isotopes Foraminifera)" project. The Biological and Chemical Oceanography Data Management Office (BCO-DMO) submitted these data to NCEI on 2020-03-13. The following is the text of the dataset description provided by BCO-DMO: Nitrate+nitrite and nitrate-only δ15N from the Southern Ocean south of Africa Dataset Description: Nitrate+nitrite and nitrate-only δ15N from the Southern Ocean south of Africa. The dataset includes hydrocast (depth-profile) and underway (surface; intake at 7 m depth) data. The former is accompanied by hydrographic data obtained during the CTD cast. |
| Date received: | 20200313 |
| Start date: | 20150726 |
| End date: | 20160509 |
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| West boundary: | 0 |
| East boundary: | 38.499 |
| North boundary: | -39.411 |
| South boundary: | -54 |
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| Submitting institution: | Biological and Chemical Oceanography Data Management Office |
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| Supplementary information: | Acquisition Description: Seawater samples were collected aboard the R/V S.A. Agulhas II (from CTD Niskin bottles and the underway intake) and immediately frozen at −20°C until analysis. Hydrographic data for each profile station were acquired from a conductivity-temperature depth (CTD) sensor mounted on the Niskin bottle rosette. An aliquot of each seawater sample was treated with sulfamic acid to remove nitrite (Granger & Sigman, 2009). Both nitrate+nitrite and nitrate-only samples were measured for concentration by chemiluminescence (Braman & Hendrix, 1989) and isotope composition using the denitrifier method (Sigman et al., 2001). Briefly, sample nitrate or nitrate+nitrite is converted to N₂O gas by denitrifying bacteria and measured for N isotope composition by GC-IRMS with an on-line N₂O extraction and purification system (Sigman et al., 2001; Casciotti et al., 2002; Weigand et al., 2016). The pooled standard deviations (1σ) of replicate denitrifier measurements was 0.09‰ for nitrate+nitrite δ¹⁵N and 0.06‰ for nitrate-only δ¹⁵N. Hydrographic profiles were acquired by a Sea-Bird conductivity-temperature depth sensor during each cast. The isotopic composition of N₂O was measured at Princeton University by GC-IRMS using a Thermo MAT 253 mass spectrometer with a purpose-built on-line N₂O extraction and purification system. See methods section of Smart et al. (2020) for more detail. |
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| Metadata version: | 1 |
| Keydate: | 2023-05-06 04:29:34+00 |
| Editdate: | 2023-05-06 04:30:14+00 |