Heidelberg 2015 – wissenschaftliches Programm

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UP: Fachverband Umweltphysik

UP 10: Ozeanographie

UP 10.5: Vortrag

Donnerstag, 26. März 2015, 18:15–18:30, G/gHS

Fingerprinting North Atlantic water masses near Iceland using Nd-isotopes — •Norbert Frank¹, Astrid Waldner², Paolo Montagna³, Christophe Colin⁴, and Qiong Wu⁵ — ¹Institut für Umweltphysik, INF229, Heidelberg — ²Paul Scherrer Institute, Villigen, Switzerland — ³CNR - ISMAR, Bologna, Italy — ⁴IDES, Université de Paris-Sud, Orsay, France — ⁵State Key Laboratory, Tongji University, Shanghai, China

The radiogenic ¹⁴³Nd/¹⁴⁴Nd ratio of seawater is a valuable tracer of north Atlantic circulation pathways, driven by continental runoff (freshwater and Aeolian dust), boundary exchange and advection and thus mixing patterns. A region of particular interest in the North Atlantic is the overflow across the Iceland-Scotland Ridge injecting water from the Arctic Ocean into the Iceland basin (Iceland Scotland Overflow Water). However, Iceland itself constitutes a local source for Nd due to possible leaching of young volcanic basalts adding radiogenic ¹⁴³Nd/¹⁴⁴Nd to seawater. We have conducted an intense survey of physical properties and Nd-isotope composition between Iceland and the Azores that allows to fingerprint different water masses of the North Atlantic through the ¹⁴³Nd/¹⁴⁴Nd ratio and that demonstrates the very local influence of volcanic material to the seawater Nd cycle. A first local transect is achieved from the open ocean to the outflow of the Vatnajökull glacier. Runoff influences seawater Nd in close vicinity (<40km near the outflow). A along shelf transect provide a similar observation. From Iceland to the Azores, however, water masses of the sub-tropical and sub-polar gyre are clearly distinguishable.