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UP: Fachverband Umweltphysik
UP 10: Ozeanographie
UP 10.5: Talk
Thursday, March 26, 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.