Water mass provenance and mixing in the Fram Strait, Arctic Ocean – Multi-proxy evidence from dissolved Nd isotopes, REEs, Ba, nutrients, and δ18O

Laukert, Georgi, Frank, Martin, Hathorne, Ed, Bauch, Dorothea, Wegner, Carolyn, Cao, Zhimian, Zieringer, Moritz, Andersen, Nils and Kassens, Heidemarie (2014) Water mass provenance and mixing in the Fram Strait, Arctic Ocean – Multi-proxy evidence from dissolved Nd isotopes, REEs, Ba, nutrients, and δ18O [Poster] In: AGU Fall Meeting 2014, 15.12.-19.12.2014, San Francisco, California, USA.

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Abstract

OS51C-1004
Dissolved radiogenic Nd isotopes (εNd), rare earth element (REE), Ba, and nutrient concentrations combined with oxygen isotopes retrieved along a section between Spitsbergen and Greenland at approximately 79°N during the ARK XXVII/1 cruise in 2012 were measured to characterize the origin and mixing of the water masses in the Fram Strait.

Deep waters below 500 m are nearly constant in Nd concentration (CNd) around 16 pmol/kg and εNd signatures range from -9.5±0.2 to -10.9±0.2. The heavy REE to light REE ratio (HREE/LREE) ranges from 4 to 5. Ba concentrations range from 47 to 58 nmol/kg, increasing slightly with depth. These homogeneous signatures do not allow identification of distinct deep water masses.

The upper 500 m of the water column close to the Western Svalbard margin including the shelf is relatively warm and saline (T ≤ 5.5°C, S ≤ 35.1) and shares characteristics of Atlantic Water (AW) including low CNd (~15 pmol/kg) and relatively unradiogenic εNd signatures (-12.2±0.2). This water is also characterized by HREE/LREE around 4 and CBa around 50 nmol/kg.

Low salinity surface waters on the East Greenland shelf have unradiogenic εNd signatures similar to AW (-12.4±0.3) but in contrast to AW high CNd of up to 37 pmol/kg. At the same time the HREE/LREE ratio is relatively low (~3.5) and CBa reaches 73 nmol/kg. This suggests a significant freshwater contribution either from the McKenzie or the Lena rivers. Eastwards of these freshwater-influenced waters (at ~5°W), admixture of a Pacific component characterized by a more radiogenic εNd (-8.8±0.2) and high nutrient concentrations outcropping at surface was detected. Waters of the same origin are present on the East Greenland shelf at about 150 m depth.

Based on these data we use mass balance calculations to determine the fractions of sea ice meltwater, Eurasian run-off, North American run-off, and Arctic seawater and compare these results with our εNd and REE data.

Document Type: Conference or Workshop Item (Poster)
Keywords: Seawater; Fram Strait; Arctic Ocean
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
Related URLs:
Projects: Laptev Sea System, Transdrift
Date Deposited: 28 Aug 2014 12:48
Last Modified: 27 Feb 2015 08:32
URI: http://eprints.uni-kiel.de/id/eprint/25490

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