Petrova, Mariia (2015) Neodymium isotopes and rare earth element distribution in the Barents Sea, Arctic Ocean. (Master thesis), Saint Petersburg State University / University of Hamburg, Saint Petersburg / Hamburg, 60 pp.

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Abstract

The Barents Sea is a key region for water mass modification in the Arctic. Interaction with atmosphere and ice, and mixing in the Barents Sea, significantly modify the water masses before they enter the Arctic Basin. In the eastern Barents Sea mixing of water masses generates dense Barents Sea Water (BSW) which inflows the Arctic Ocean to form the Arctic Intermediate Waters. BSW plays an important role in the maintenance of the Arctic halocline. To study the interannual variability and evolution of water masses passing through the Barents Sea could be useful for better understanding of the climate change in the Northern Hemisphere.
Neodymium is one of number tracers which have been used to trace the distribution and circulation of water masses within the Barents Sea. Neodymium isotopic composition (expressed as ɛNd) has been successfully applied for water mass tracing due to the residence time of Nd in the oceans being shorter than the ocean overturning time and due to independence of Nd from biological fractionation and physical processes.
This work examines the major water masses within the Barents Sea, using temperature, salinity, REE concentrations and ɛNd isotopic composition data of seawater.
Water within the Barents Sea are a mixture of the saline, warm and unradiogenic Atlantic water; fresh, warm, unradiogenic, and REE-enriched Coastal water from the Kola Peninsula; fresh, cold, and relatively radiogenic Arctic surface water; and fresh, most radiogenic in this area and depleted in LREE Ob/Yenisei River Current water in different proportion. Particle scavenging is very important processes for modification of chemical content of water masses. As a result of water mass transformation, waters in southwestern part of the sea have ɛNd=-12.9±0.2 with relatively low HREE/LREE ratio=3.20±0.30. In the central part of the sea, where the Arctic waters have a stronger influence, ɛNd is -10.6±0.2 in the surface layer, but near the bottom the Nd isotopic signature indicates presence of Atlantic water (ɛNd=-12.0±0.2). The Nd isotopic composition in the northern parts of Barents Sea is more radiogenic (ɛNd=-9.1±0.3) and a maximum of the HREE/LREE ratio is reached due to particle scavenging. In the northeastern part of the study area the most radiogenic signature (ɛNd=-8.5±0.3) was determined reflecting admixture of radiogenic Ob/Yenisei River water.

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