Sea ice core biogeochemical data collected during the 2019 SCALE Winter Cruise

Title: Biogeochemical profiles of sea ice cores sampled during the Southern oCean seAsonal Experiment (SCALE) winter cruise in 2019. Authors: Riesna R. Audh, Siobhan Johnson, Mark Hambrock, Hazel Little, Joshua Mirkin, Emmanuel Omatuku, Benjamin Hall, Tokoloho Rampai, Keith MacHutchon, Sebastian Skatulla, Sarah E. Fawcett, Marcello Vichi Data Description: Abstract Biogeochemical profiles of sea ice cores extracted from in situ sea ice floes and lifted pancakes were measured in the Atlantic sector of the Antarctic Marginal Ice Zone during the Southern oCean seAsonal Experiment (SCALE) winter cruise in 2019 (www.scale.org.za) aboard the SA Agulhas II. A total of four sea ice cores (cores) were sampled during the cruise. Two cores were collected overboard on a consolidated floe that was accessed via a personnel carrier suspended by the ship’s forward crane. Two cores were collected from a pancake that was lifted aboard the ship via a net that was attached to the ship’s aft crane and placed on the helideck for sampling. Profiles were obtained by cutting the cores using a bandsaw in a cold laboratory at -10 °C. The cores were cut into approximately 0.05 m segments, starting from the bottom of the core. These segments were allowed to melt in the dark in an insulated box. The meltwater was filtered for chlorophyll measurements (Welschmeyer, 1994) and the filtrate was analysed for oxygen isotopes (Walker and others, 2015), ammonium (Holmes et al., 1999), phosphate, nitrate, nitrite and silicate (using a SEAL AA500 segmented flow autoanalyser). These values are reported at the depth of the top of the segment in the core in μM. In order to facilitate comparison with the seawater concentrations below the ice, the in-ice nutrients (including NH4+) were salinity normalised using the equation of Fripiat and others (2017): Cnorm = CSwS Where C is the measured bulk concentration, Sw is the salinity of the seawater, and S is the corresponding measured bulk salinity of the ice segment. Although sampling of the core occurred from the bottom of the core to the top of the core, the data are reported as the top of the core (snow/ice interface) being 0 m (depth=0 m). This research has been funded by the National Research Foundation of South Africa (NRF) Cruise: VOY-038 (SCALE2019-WINTER) (URL: https://scale.org.za/) Station(s): VOY-038-MIZ3A VOY-038-MIZ1D Position(s): -58.13783 S; 0.00442 W -56.8017 S; 0.30262 E Date/Time: 2019-07-27/10:38:00 2019-07-28/09:15:00 Method(s): Overboard coring Pancake lifting via aft crane, on deck coring Parameters: Station Number (Station) Date/Time of station (Date/Time) Latitude of station (Latitude) Longitude of station (Longitude) Ice type (Ice Type) Core ID(Core), Pancake identifier A/B/C/D Oxygen isotopes (d18O) Chlorophyll (Chl-a) Ammonium (NH4) Nitrate + Nitrite (NO3+NO2) Nitrite (NO2) Phosphate (PO4) Silicate (Si) Nitrate (NO3) Salinity of the ice segment from physical cores (IceSalinity) Standard deviation of the salinity average from physical cores (IceSalinityStdev) Seawater salinity from CTD (SeawaterSalinity) Salinity normalised nitrate+nitrite (N03+N02_Avg_SalinityNormalised) Salinity normalised ammonium (NH4_SalinityNormalised) Salinity normalised nitrite (NO2_SalinityNormalised) Salinity normalised phosphate (PO4_SalinityNormalised) Salinity normalised silicate (Si_SalinityNormalised) Salinity normalised nitrate (NO3_SalinityNormalised) Keywords: sea ice cores, Antarctica, pancake ice, sea ice, biogeochemistry, winter References: Fripiat, F., Meiners, K.M., Vancoppenolle, M., Papadimitriou, S., Thomas, D.N., Ackley, S.F., Arrigo, K.R., Carnat, G., Cozzi, S., Delille, B. and Dieckmann, G.S., 2017. Macro-nutrient concentrations in Antarctic pack ice: Overall patterns and overlooked processes. Elementa: Science of the Anthropocene, 5. Holmes, R.M., Aminot, A., Kérouel, R., Hooker, B.A. and Peterson, B.J., 1999. A simple and precise method for measuring ammonium in marine and freshwater ecosystems. Canadian Journal of Fisheries and Aquatic Sciences, 56(10), pp.1801-1808. Walker, S.A., Azetsu‐Scott, K., Normandeau, C., Kelley, D.E., Friedrich, R., Newton, R., Schlosser, P., McKay, J.L., Abdi, W., Kerrigan, E. and Craig, S.E., 2016. Oxygen isotope measurements of seawater (18O/16O): A comparison of cavity ring‐down spectroscopy (CRDS) and isotope ratio mass spectrometry (IRMS). Limnology and Oceanography: Methods, 14(1), pp.31-38. Welschmeyer, N., 1994. A method for the determination of chlorophyll a in the presence of chlorophyll b and pheopigments. Limnology and Oceanography, 39, pp.1985-1992.

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