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XX Seminario Ibérico de Química Marina (SIQUIMAR 2020) - XX Iberian Seminar on Marine Chemistry, 1-3 July 2020, Barcelona.-- 2 pages.-- Samples were collected during the NextData Cruise on R/V Minerva I in June 2016, The present study aims at shedding light on the central Mediterranean Sea (MS) functioning in terms of water mass mixing and potential lithogenic sources by means of new geochemical tracers such as dissolved Nd isotopes (εNd) and Rare Earth Element (REE: La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) concentrations. Although proved to be valuable tracers of oceanographic processes, their measurements are basically lacking in the MS water column. We analyzed 9 stations around the Tyrrhenian, Ionian and Ligurian seas. Dissolved REE were measured with an Agilent 7500 ICP-MS and εNd using a Nu Plasma-III MC-ICP-MS at UB. The obtained REE do not display nutrient-like profiles, likely suggesting relatively young waters with limited accumulation of remineralized REE. Light REE (LREE: from La to Gd) present a non-conservative behavior, largely peaking at surface waters and rapidly decreasing with depth. The negative linear correlation of surface LREE enrichment with offshore distance indicates their release from lithogenic sediments of the Italian coast to the Tyrrhenian waters. In contrast to other regions, this process does not modify the εNd values. On the other side, distributions of dissolved heavy REE (HREE: Tb to Lu) and εNd exhibit a conservative behavior that can be explained by mixing of western- (MAW and WMDW) and eastern- (LIW and EMDW) originated waters. We test this hypothesis with an Optimum Multi-Parameter Analysis (OMPA) including HREE and εNd parameters. Even though the limited data set, consistent results of water mass fractions are obtained for the four main water masses although with some particularities. While LIW take on major importance when considering HREE in the model, EMDW fractions are preferentially detected with εNd. This latter finding implies a noticeable deep-water flux across the Sicily Strait into the Western Mediterranean that was not clearly evidenced before, The authors thank financial support from the OPERA Project (CTM2013-48639-C2-1-R), the CHIMERA Project (CTM2016-75411-R) and Generalitat de Catalunya (2017 SGR 315). This work has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant agreement No. 683237)

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