Basak, Chandranath; Pahnke, Katharina; Frank, Martin; Lamy, Frank; Gersonde, Rainer (2014): Neodymium isotopic characterization of Ross Sea Bottom Water and its advection through the southern South Pacific, POLARSTERN cruise ANT-XXVI/2. PANGAEA, https://doi.org/10.1594/PANGAEA.834728, Supplement to: Basak, C et al. (2015): Neodymium isotopic characterization of Ross Sea Bottom Water and its advection through the southern South Pacific. Earth and Planetary Science Letters, 419, 211-221, https://doi.org/10.1016/j.epsl.2015.03.011
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Since the inception of the international GEOTRACES program, studies investigating the distribution of trace elements and their isotopes in the global ocean have significantly increased. In spite of this large-scale effort, the distribution of neodymium isotopes (143Nd/144Nd) and concentrations ([Nd]) in the high latitude south Pacific is still understudied. Here we report dissolved Nd isotopes and concentrations from 11 vertical water column profiles from the south Pacific between South America and New Zealand. Results suggest that Ross Sea Bottom Water (RSBW) is represented by an epsilon-Nd value of ~ -7, and is thus more radiogenic than Circumpolar Deep Water (epsilon-Nd ~ -8). RSBW and its characteristic epsilon-Nd signature can be traced far into the SE Pacific until progressive mixing with ambient Lower Circumpolar Deep water (LCDW) dilutes this signal north of the Antarctic Polar Front (APF). The SW-NE trending Pacific-Antarctic Ridge restricts the advection of RSBW into the SW Pacific, where bottom water density, salinity, and epsilon-Nd values of -9 indicate the presence of bottom waters of an origin different from the Ross Sea.
Neodymium concentrations show low surface concentrations and a linear increase with depth north of the Polar Front. South of the APF, surface [Nd] is high and increases with depth but remains almost constant below ~1000 m. This vertical and spatial [Nd] pattern follows the southward shoaling density surfaces of the Southern Ocean frontal system and hence suggests supply of Nd to the upper ocean through upwelling of Nd-rich deep water. Low particle abundance dominated by reduced opal production and seasonal sea ice cover likely contributes to the maintenance of the high upper ocean [Nd] south of the APF.
The reported data highlights the use of Nd isotopes as a water mass tracer in the Southern Ocean, with the potential for paleocenaographic reconstructions, and contributes to an improved understanding of Nd biogeochemistry.
Median Latitude: -58.533804 * Median Longitude: -142.152626 * South-bound Latitude: -68.729670 * West-bound Longitude: 177.147680 * North-bound Latitude: -45.757020 * East-bound Longitude: -80.086450
Date/Time Start: 2009-11-29T23:44:00 * Date/Time End: 2010-01-22T19:41:00
Minimum DEPTH, water: 10.5 m * Maximum DEPTH, water: 5162.0 m
PS75/034-3 * Latitude: -54.368520 * Longitude: -80.086450 * Date/Time: 2009-11-29T23:44:00 * Elevation: -4436.0 m * Location: South Pacific Ocean * Campaign: ANT-XXVI/2 (PS75 BIPOMAC) * Basis: Polarstern * Method/Device: CTD/Rosette (CTD-RO) * Comment: to bottom, fluorometer failed
PS75/044-1 * Latitude: -56.086470 * Longitude: -96.775980 * Date/Time: 2009-12-06T05:11:00 * Elevation: -5013.0 m * Location: South Pacific Ocean * Campaign: ANT-XXVI/2 (PS75 BIPOMAC) * Basis: Polarstern * Method/Device: CTD/Rosette (CTD-RO) * Comment: to bottom
|#||Name||Short Name||Unit||Principal Investigator||Method/Device||Comment|
|1||Event label||Event||Basak, Chandranath|
|2||Date/Time of event||Date/Time||Basak, Chandranath|
|3||Latitude of event||Latitude||Basak, Chandranath|
|4||Longitude of event||Longitude||Basak, Chandranath|
|5||DEPTH, water||Depth water||m||Basak, Chandranath||Geocode|
|7||Temperature, water, potential||Tpot||°C||Gersonde, Rainer||Calculated|
|8||Density, sigma-theta (0)||Sigma-theta||kg/m3||Basak, Chandranath||Calculated|
|9||Neutral density||gamma n||kg/m3||Basak, Chandranath||Calculated|
|10||Neodymium 143/Neodymium 144||143Nd/144Nd||Basak, Chandranath||see reference(s)|
|11||Neodymium 143/Neodymium 144, error||143Nd/144Nd e||±||Basak, Chandranath||see reference(s)||internal error, 2 sigma|
|12||ε-Neodymium||ε-Nd||Basak, Chandranath||see reference(s)|
|13||ε-Neodymium, standard deviation||ε-Nd std dev||±||Basak, Chandranath||see reference(s)||2 sigma|
|14||ε-Neodymium, error||ε-Nd e||±||Basak, Chandranath||see reference(s)||reported error|
|15||Neodymium, dissolved||Nd diss||pmol/kg||Basak, Chandranath||see reference(s)|
|16||Neodymium, dissolved, standard error||Nd diss std e||±||Basak, Chandranath||see reference(s)||absolute standard error|
|17||Comment||Comment||Basak, Chandranath||see reference(s)||mass spectrometer used|
771 data points