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://oceanrep.geomar.de/id/eprint/25490

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