Depth to sea floor and sea ice thickness data measured at various locations around the Vestfold Hills, Davis station, East Antarctica, during the 2018-19 austral summer. Depth to sea floor and sea ice thickness measures in meters obtained using a weighted tape measure deployed through a hole (5 cm) drilled in the sea ice. Sea ice thickness was determined by snagging the weight on the underside edge of the ice hole as the tape measure was retreived.

Overview of the project and objectives: To investigate whether nitrate uptake and processes other than nitrate uptake by phytoplankton are significant and show spatial variability possibly induced by varying availability of Fe and other parameters in the region, seawater was collected from CTD (Conductivity, Temperature and Depth) and TMR (Trace Metals Rosette) casts jointly with the nutrient sampling, as well as well as sea-ice collected from Bio ice-core types on Ice Station, for analysis of nitrate d15N, d18O isotopic composition. Results have been interpreted in the light of prevailing nitrate-nutrient concentrations (Belgian team) and N-uptake regimes for the Ice Stations (new vs. regenerated production and nitrification; see Silicon, Carbon and Nitrogen in-situ incubation Metadata file). Methodology and sampling strategy: Samples for isotopic composition of nitrate were collected from the CTD rosette, TMR and Bio ice-core jointly with the nutrient sampling. Sea-ice sampling: sampling strategy follows ice stations deployment via Bio ice-core type. Most of the time we worked close to / directly on the Trace Metal site following precautions concerning TM sampling (clean suits etc.). When we worked close to the TM site, precautions were not such important because we don't need the same drastic precautions for our own sampling. We work together because we want to propose a set of data which helps to characterize the system of functioning in close relation with TM availability (for that, sampling location have to be as close as possible). All samples were filtered on 0.2 microns acrodiscs and kept at -20 degrees C till analysis in the home-based laboratory. We applied the denitrifier method elaborated by Sigman et al. (2001) and Casciotti et al. (2002). This method is based on the isotopic analysis of delta 15N and delta 18O of nitrous oxide (N2O) generated from nitrate by denitrifying bacteria lacking N2O-reductase activity. As a prerequisite the nitrate concentrations need to be known (nutrients analysis in the home lab.) as this sets sample amount provided to the denitrifier community. Briefly, sample nitrate is reduced by a strain of denitrifying bacteria (Pseudomonas aureofaciens) which transform nitrate into N2O, but lack the enzyme to produce N2. N2O is then analysed for N, O isotopic composition by IRMS (Delta V, Thermo) after elimination of CO2, volatile organic carbon and further cryogenic focusing of N2O (Mangion, 2011). Casciotti K.L., D.M.Sigman, M.G. Hastings, J.K. Bohlke and A. Hilkert, 2002. Measurement of the oxygen isotopic composition of nitrate in seawater and freshwater using the denitrifier method, Analytical Chemistry, 74 (19): 4905-4912. Mangion P., 2011. Biogeochemical consequences of sewage discharge on mangrove environments in East Africa, PhD Thesis, Vrije Universiteit Brussel, 208 pp. Sigman D.M., Casciotti K.L., Andreani M., Barford C., Galanter M. and J.K. Bohlke, 2001. A bacterial method for the nitrogen isotopic analysis of nitrate in seawater and freshwater, Analytical Chemistry, 73: 4145-4153.

Twenty-six marine and lacustrine sediment cores were taken from Windmill Islands during the 1998/99 season. They have been analysed for physical, chemical and biological parameters by a multidisciplinary team under ASAC project 1071. The download file contains 12 Excel spreadsheets of data.

Metadata record for data from ASAC Project 2534 See the link below for public details on this project. The Holocene sea-ice project brings together for the first time, records from the Antarctic continent and deep sea sediments that will allow us to calibrate three sea-ice extent surrogates, validate their use in contrast to satellite observations and explore climatic influence on the physio-ecological environment over the last 10,000 years. Taken from the 2004-2005 Progress Report: Progress Objectives: Our objective is to instigate synthesis between deep sea and continental ice core records of Antarctic sea ice variability over the Holocene (last 10,000 yrs BP). The relevance of this novel evaluation is three-fold: - To appraise for the first time the relationships between proxy sea ice predictions beyond the instrumental record from the land and sea. - To assess variability differences and similarities from the various records that can then be used to probe the dynamics of the climate/environmental system in the East Antarctic sector. - To provide insights on the ecological response sea ice plays through the Holocene. Public summary of the season progress: Basic analysis of samples from Core E27-23 have been complete except for seven new samples from near the top of the core. This includes counts of diatoms, foraminifera, ice-rafted debris, volcanic glass. A greater variety of parameters is available than expected. Dramatic downhole changes represent oceanographic changes over last 25 000 years at the site including in evidence for carbonate dissolution and water temperature. Now needs statistical analysis of diatom data, extra radiocarbon dates and integration with data from Law Dome ice-core.

This dataset is an annual reconstruction of the Interdecadal Pacific Oscillation (IPO), a decadal-scale mode of variability in the Pacific Ocean which has climate impacts across the Pacific Basin. This data is a time series spanning CE 1-2011 inclusive (ie, the Common Era). The time series is reconstructed from three primary annually-resolved proxy series from the Law Dome ice core. These three series are the log-transformed seasonal sea salt concentration for the cool season (June to November), the log-transformed seasonal sea salt concentration for the warm season (December to May) and the annual snowfall accumulation rate. The reconstruction uses a Gaussian kernel correlation reconstruction method (Roberts et al., 2019) with 2000 ensemble members, which provides a mean IPO index value for each year, as well as upper and lower quartiles. The reconstruction target time series was the observed Interdecadal Pacific Oscillation spanning 1870-2020, which had been smoothed using a Gaussian window of 13 years. This Gaussian kernel correlation reconstruction is an evolution/replacement of the method and reconstruction presented in Vance et al., (2015) to reconstruct the IPO. This is now our preferred dataset for the Law Dome IPO reconstruction, and supersedes that published by Vance et al., (2015). The time series (dataset) consists of three columns with column headings as follows: Year – where year is the year from the beginning of the Common Era, ie, ‘436.0’ means the year CE 436, and ‘2009.0’ means the year 2009. IPO (mean) – the mean of the IPO reconstruction index value Std Dev) – the standard deviation of the index value for each year.

Overview of the project and objectives: Sea-ice phytoplankton is significantly enriched in 13C (delta 13C-POC) compared to pelagic phytoplankton in adjacent open waters because of carbon limitation in the brine pockets and due to physiological properties such as the presence of Carbon Concentrating Mechanisms (CCM) and/or the uptake of bicarbonate (HCO3-). Melting of sea-ice with release of sea-ice phytoplankton occurs during the growth season, so these isotopically heavy particles, if sinking out of the surface waters, can be expected to be found deeper in the water column. One hypothesis is that the natural carbon isotopic signal of brassicasterol (phytosterol, mainly diatom indicator) in the south Antarctic Bottom Water (AABW), a water mass which is influenced by the Seasonal Ice Zone (SIZ), is enriched compared to northern deep waters signal due to an enhanced contribution of sea-ice diatoms. The objective of this dataset acquisition is to gain information on the delta 13C signal of brassicasterol in sea-ice diatoms and further estimate the contribution of sea-ice algae release in the Southern Ocean biological pump. In the course of the expedition, a second choice has been done to look at the presence of particulate barium in the sea-ice. In the open ocean, presence of particulate barium in the mesopelagic layer is an indicator of remineralisation process. The main idea is that marine snow composed of detritical organic matter (aggregates, faecal pellets, etc.) provides micro-environment favorable for precipitation of excess Barium or Baxs (total particulate Ba minus the lithogenic part; mainly constituted of barite crystals, BaSO4): is there such Baxs components in the sea-ice? Methodology and sampling strategy: Sampling strategy follows ice stations deployment via Bio ice-core type. Most of the time we worked close to / directly on the Trace Metal site following precautions concerning TM sampling (clean suits etc.). When we worked close to the TM site, precautions were not such important because we don't need the same drastic precautions for our own sampling. We work together because we want to propose a set of data which helps to characterize the system of functioning in close relation with TM availability (for that, sampling location have to be as close as possible). Ice melted from ice-core sections (see attached files for more details) is filtered on precombusted GF-F filters (0.7 microns porosity) and filters are stored at -20 degrees C. For particulate Barium sampling, same protocol but filtration on PC filters 0.4 microns, dry over night and store at ambient temperature. At home laboratory (VUB, Brussels, Belgium), sterols samples are analysed via Gas Chromatography - Mass Spectrometer (GC-MS) and Gas Chromatography-combustion column-Isotope Ratio Mass Spectrometer (GC-c-IRMS) after chemical treatment. Barium sample are analysed via Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES).

During voyage 1 of 1985, sixteen ice cores were drilled from sea ice. Details from those cores include the position they were drilled, length of the core, percentage of the core that was frazil ice, and comments on the state of the core, or observations of the ice make-up. Physical records are archived at the Australian Antarctic Division.

Overview of the project and objectives: Assessing the contribution of the different N substrates to the primary production process, such as the biogenic silica production and dissolution in the Antarctic sea-ice provides a means to understand the biogeochemical system functioning. In such a semi closed-type system, assess incorporation rates of HCO3-, NO3-, NH4+, SiOH4, BSi dissolution, nitrification, C-release in close-by ice-cores (3 ice-cores dedicated to (i) 13C-assimilation + 15NH4+ uptake rate, (ii) 13C-assimilation + 15NO3- uptake rate and nitrification, (iii) Biogenic silica production and dissolution via 30Si isotope tool) will allow improving the knowledge of system functioning. This is also closely linked to the thematic of iron availability since these experiments are done close to / on the Trace Metal site allowing us to hopefully propose a relatively complete image of biogeochemical activity and relationship with trace metals on this site. Methodology and sampling strategy: Most of the time we worked close to / directly on the Trace Metal site following precautions concerning TM sampling (clean suits etc.). When we worked close to the TM site, precautions were not such important because we don't need the same drastic precautions for our own sampling. We work together because we want to propose a set of data which helps to characterize the system of functioning in close relation with TM availability (for that, sampling location have to be as close as possible). 14C and 13C-incubation experiment intercalibration work were conducted on the Biosite (different place than TM site except for station 7) Incubation experiment samples are analyzed via (1) Elemental Analyzer - Isotope Ratio Mass Spectrometer (EA-IRMS) for carbon and nitrogen (VUB, Brussels, Belgium); (2) High Resolution Inductively Coupled Mass Spectrometer (HR-ICPMS) for silicon (RMCA, Brussels, Belgium).

This file comprises five high-resolution records of 10Be concentration in snow from Law Dome, East Antarctica: DSS0102-pit, DSS0506-pit, DSS0506-core, DSS0809-core and DSS0910-core. A single composite series is constructed from three of these records (DSS0506-core, DSS0809-core and DSS0102-pit), providing a monthly-resolved time-series of 10Be concentrations at DSS over the decade spanning 1999 to 2009. This work was done as part of AAS 2384, AAS 3064 and AAS 1172. A data update was provided by Jason Anderson on 2012-12-17.

During the Antarctic Division BIOMASS Experiment III (ADBEX III) cruise of the Nella Dan (Oct - Dec 1985), sea ice cores were drilled at 13 stations. Stratigraphy of the cores recorded, along with borehole temperatures. In addition to visual notes, photographs for each of the cores were taken - the negatives of these pictures are archived with the notes made. Physical records are archived at the Australian Antarctic Division.