Water mass transformation in the Barents Sea inferred from radiogenic neodymium isotopes, rare earth elements and stable oxygen isotopes

• Published in: Chemical geology 2019-04, Vol.511, p.416-430
• Main Authors: Laukert, Georgi, Makhotin, Mikhail, Petrova, Mariia V., Frank, Martin, Hathorne, Ed C., Bauch, Dorothea, Böning, Philipp, Kassens, Heidemarie
• Format: Article
• Language: English
• Subjects: Arctic Ocean; Barents Sea; Neodymium isotopes; Rare earth elements; Scavenging; Water masses
• ISSN: 0009-2541; 1872-6836
• DOI: 10.1016/j.chemgeo.2018.10.002

Nearly half the inflow of warm and saline Atlantic Water (AW) to the Arctic Ocean is substantially cooled and freshened in the Barents Sea, which is therefore considered a key region for water mass transformation in the Arctic Mediterranean (AM). Numerous studies have focused on this transformation and the increasing influence of AW on Arctic climate and biodiversity, yet geochemical investigations of these processes have been scarce. Using the first comprehensive data set of the distributions of dissolved radiogenic neodymium (Nd) isotopes (expressed as ɛNd), rare earth elements (REE) and stable oxygen isotope (δ18O) compositions from this region we are able to constrain the transport and transformation of AW in the Barents Sea and to investigate which processes change the chemical composition of the water masses beyond what is expected from circulation and mixing. Inflowing AW and Norwegian Coastal Water (NCW) both exhibit distinctly unradiogenic ɛNd signatures of −12.4 and −14.5, respectively, whereas cold and dense Polar Water (PW) has considerably more radiogenic ɛNd signatures reaching up to −8.1. Locally formed Barents Sea Atlantic Water (BSAW) and Barents Sea Arctic Atlantic Water (BSAAW) are encountered in the northeastern Barents Sea and have intermediate ɛNd values resulting from admixture of PW containing small amounts of riverine freshwater from the Ob (