The purpose of this study is to use dissolved Rare Earth Elements (dREE) and Nd isotopes (εNd) in sea water to better understand water-mass exchange and pathways in the Central Mediterranean (CM) Sea. We have analyzed 9 hydrographic stations around the Tyrrhenian Sea, Strait of Sicily and Ionian Sea (NextData2016 Cruise). Pre-concentrated and purified dREE were measured with an Agilent 7500 quadrupole ICP-MS while Nd isotopes (εNd) were determined using a Nu Plasma III Multicollector ICP-MS. In general, dREE abundances in the CM are similar to the western Mediterranean [1] but clearly lower than in the eastern basin [2] pointing to an eastward enrichment of Atlantic Waters, as for other trace metals. In addition, inflowing Atlantic Waters (εNd≈-10) become more radiogenic within its circulation (εNdup to -6). Light REE (LREE) present highest concentrations at surface waters, probably indicating lithogenic inputs. This is specially marked at the station closest to the continental margin with LREE enrichments relative to the other stations of 20-50%, with no significant εNd modification. Far from continental margins and below the surface, well-developed oceanic dREE patterns are found displaying negative cerium anomalies (Ce*=0.20-0.30) and enrichment of Heavy REE (HREE) demonstrating that water mass mixing governs the REE distribution below the permanent thermocline. Levantine Intermediate Waters (LIW) can be traced through a substantial HREE peak and distinctive radiogenic neodymium signature (εNd=-6.4). This is coherent with older waters enhanced with conservative HREE. Concerning εNd, the radiogenic imprint of LIW is in accordance with either the influence of partially dissolved Nile river particles [2] or the rock signature in the LIW formation zone [3]. Finally, both dHREE and εNd can be used to distinguish deep water masses: EMDW present εNd≈-6.7 and WMDW show εNdof -8.5, with the first being 13% more enriched in dHREE than the later

We authors thank financial support from the Italian Project of Strategic Interest NEXTDATA (http://www.nextdataproject.it) “A national system for recovery, storage, accessibility and dissemination of environmental and climatic data from mountain and marine areas” and from the OPERA Project (CTM2013-48639-C2-1-R) and Generalitat de Catalunya-Grups de Recerca Consolidats (2017 SGR 315). This work has been partially funded by the European Commission through an ERC Consolidator Grant to I. Cacho (TIMED; ID: 683237). Support from the Spanish Government for a post-doctoral fellowship to E. G-S. (FPDI-2013-15660) is also recognized. L.P. acknowledges support from the Ramón y Cajal program (MINECO, Spain). J.N.P-A. has been funded by a Postdoctoral fellowship Beatriu de Pinós (Generalitat de Catalunya, Marie Curie-COFUND actions)

VI Simposio Internacional de Ciencias del Mar - VI International Symposium of Marine Sciences (ISMS 2018), 20- 22 June 2018, Vigo.-- 2 pages

Peer Reviewed