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Abstract:
The data has been collected during the monitoring cruise (NPI, Transekttokt) in Kong Håkon VII Hav from 2021 until today. The sampling covers a transect from the ice shelf across the shelf break into the deep ocean at approximately 6° East but also includes other opportunistic stations in the area. The samples were collected using a 12-Niksin-bottle SBE32 carousel water sampler equipped with CTD (conductivity-temperature-depth; SBE91+ system).
TT21: Transekttokt 2021 from December 31, 2020 to January 14, 2021 on cargo vessel CV Malik Arctica
Standard depths:
- POC/PON & chlorophyll: 100, 75, 50, Chl-a max, 25, 10 m
- Nutrients: bottom, 3000, 2000, 1500, 1000, 750, 500, 250, 150, 100, 75, 50, Chl-a max, 25, 10 m
Measured variables include:
Inorganic nutrients (nitrate, nitrite, phosphate, silicate & ammonium)
- Ammonium (NH4+) [mmol/m3]
- Nitrite (NO2-) [mmol/m3]
- Nitrate (NO3-) [mmol/m3]
- Phosphate (PO43-) [mmol/m3]
- Silicate (SiO44-) [mmol/m3]
Ratio of stable oxygen isotopes in seawater (δ18O)
- δ18O [‰]
Chlorophyll a & phaeopigments
- Chl a [mg/m3]
- Phaeopigment [mg/m3]
Particulate organic carbon and nitrogen (POC / PON)
Concentration in gram per volume:
- PON [µg/L]
- POC [µg/L]
Concentration in mol per volume:
- PON [µmol/L]
- POC [µmol/L] NB: µmol/l = mmol/m3 (1l = 0 0.001m3 & 1µmol = 0.001mmol)
Methods
Method nutrients
Samples for the analysis of macronutrients (nitrate, nitrite, ammonium, phosphate, and silicic acid) were fixed with 200 µL of chloroform and refrigerated at 4 °C (for analysis at Vrije Universiteit) or sterile filtered (0.2 µm) and stored –20 °C in the dark (for analysis at UiT). Samples from 2021 were analysis at the Vrije Universiteit, Brussels, Belgium using a QuAAtro Autoanalyzer and the spectrophotometric method described by Grasshof et al. (1983). Samples from 2022 onward were analysed at UiT The Arctic University of Norway. At UiT macronutrient concentrations were measured in triplicate using a QuAAtro39 Continuous Segmented Flow Analyzer (Seal Analytics, Germany) and standard colorimetric methods (e.g., Hydes et al., 2010 ) using the protocols No. Q-068-05 Rev. 12 for nitrate (NO3; detection limit = 0.02 µmol L-1), No. Q-068-05 Rev. 12 for nitrite (NO2; detection limit = 0.07 µmol L-1), No. Q-064-05 Rev. 8 for phosphate (PO4; detection limit = 0.01 µmol L-1), and No. Q-066-05 Rev. 5 for silicate (dSi; detection limit = 0.07 µmol L-1). Analysis of macronutrient concentration data was done using the AACE software (SEAL Analytical, Germany). Reference standards of nutrient concentrations in seawater (Ocean Scientific International, LTD., United Kingdom) were used to verify instrument calibration.
Method ratio of stable oxygen isotopes in seawater (δ18O)
Samples for δ18O were stored at 4 °C in the dark until measurement with a Perspective (Nu Instrument, Ametek) isotope ratio mass spectrometer coupled to a Gas Bench system in the AMGC laboratory at the Vrije Universiteit, Brussels, Belgium (Epstein and Mayeda, 1953; Harmon, 1961). All samples for δ18O were standardized against V-SMOW, and the standard deviation of the δ18O analyses was 0.1‰.
Method Chlorophyll a
Samples for Chlorophyll a were filtered through 0.7 µm GF/F filters (GE Healthcare, Little Chalfont, UK) under low vacuum pressure (approximately −30 kPa), extracted with 100% methanol for approximately 24 hours, and stored at 4 °C in dark conditions (Holm-Hansen and Riemann, 1978). The pigment concentration, including phaeopigments, was measured with a Turner Trilogy Fluorometer (Turner Design, Inc.), which had been calibrated with Chl a standards from Turner Designs (Sunnyvale, California) prior to the cruise following the JGOFS protocol 35 (Knap et al., 1996).
Method particulate organic carbon (POC) and nitrogen (PON)
Samples for POC and PON analyses were filtered through pre-combusted 25mm Whatman 0.7 µm GF/F filters (GE Healthcare, Little Chalfont, UK) under low vacuum pressure (approximately −30 kPa; Moran et al., 1999). Samples for POC and PON were stored at −20 °C during shipment, then prepared for analysis by drying at 60 °C and acidifying in fuming hydrochloric acid. POC and PON concentrations were measured with a coupled element analyzer mass spectrometer (Europa Scientific, ANCA-MS 20-20 15N/13C) at the Tvärminne Zoological Station, Finland. All readings were blank-corrected.
Data structure:
The data is following Darwin Core nomenclature as far as possible but also includes variables that aren’t supported by Darwin Core.
Header name index
Event parameters
- expedition: cruise number for C/V Silver Arctic, C/V Malik Arctica or another vessel
- eventDate: the date-time when an event occurred, using ISO 8601-1:2019 format (2020-07-27T07:16:03.446Z).
- locationID: station name
- decimalLongitude: geographic latitude (in decimal degrees, using the spatial reference system given in geodetic datum)
- decimalLatitude: geographic longitude (in decimal degrees, using the spatial reference system given in geodeticDatum)
- bottomDepthInMeters: bottom depth in meters
- gearType: the gear used to take the sample e.g. MultiNet 200 µm
- maximumDepthInMeters: sampling depth
- fieldNumber: human-readable sample ID (e.g. ZNUT-001)eventRemarks: comments or remarks about the event (free text field)
- sampleRemark: info about the sample
Result parameters
Nutrients
- fieldNumber: sample ID
- NO2 [mmol/m3]
- NO3 [mmol/m3]
- NH4 [mmol/m3]
- PO4 [mmol/m3]
- Si [mmol/m3]
δ18O
- fieldNumber: sample ID
- δ18O [‰]
Chlorophyll
- fieldNumber: sample ID
- Chlorophyll a [mg/m3]
POC/PON
- fieldNumber: sample ID
- PON [µg/L]
- POC [µg/L]
- analyseRemark
References
- Epstein, S, Mayeda, T. 1953. Varation of O18 content of waters from natural sources. Geochimica et Cosmochimica Acta 4(5):213–224. doi: 10.1016/0016-7037(53)90051-9.
- Grasshoff, K. (1965), On the Automatic Determination of Phosphate, Silicate and Fluoride in Seawater. ICES Hydrographic Committee Report No. 129.
- Harmon, C. 1961. Isotopic variations in meteoric waters. Science 133(3465): 1702–1703. doi: 10.1126/science.133.3465.1702.
- Holm-Hansen, O, Riemann, B. (1978). Chlorophyll a Determination: Improvements in Methodology. Oikos 30(3): 438–447. doi:10.2307/3543338.
- Knap, A., Michaels, A., Close, A., Ducklow, H. & Dickson A. (1996), Measurement of Chlorophyll a and Phaeopigments by fluorometric analysis. JGOFS report 19: 118-122.
- Moran, SB, Charette, MA, Pike, SM, Wicklund, CA. (1999). Differences in seawater particulate organic carbon concentration in samples collected using small- and large-volume methods: the importance of DOC adsportion to the filter blank. Marine Chemistry 67(1–2): 33–42. doi: 10.1016/S0304-4203(99)00047-X.