Rare Earth Elements and neodymium isotopes as tracers in the Mediterranean Sea

Garcia-Solsona and co-workers (2020, see reference below) analysed 9 seawater stations around the central Mediterranean Sea (MS) to clarify the relative importance of external sources, vertical (biogeochemical) processes and lateral water mass transport in controlling Rare Earth Elements (REE) and neodymium isotopic composition (εNd) distributions.

Their results clearly identify the influence of continental input from the western Italian coast to the Tyrrhenian surface waters, marked by a negative correlation of surface light REE enrichment with offshore distance.

Contrastingly, a reasonable conservative behaviour of heavy REE and εNd is observed in the Central MS. This contrast induces a decoupling of [Nd] and εNd in all water masses of the central MS below the thermocline.  

The conservativity of heavy REE and εNd as water mass mixing tracers was successfully established using an Optimum Multi-Parameter Analysis (OMPA) and confirming that the distributions of heavy REE and εNd signals are determined by mixing of the water masses present in the region: Modified Atlantic Water (MAW), Levantine Intermediate Water (LIW), Eastern Mediterranean Deep Water (EMDW) and Western Mediterranean Deep Water (WMDW). From their results, authors further suggest that εNd helps traditional oceanographic tracers in better defining the intrusion of EMDW through the Strait of Sicily to the western Mediterranean basin.

HiRes
Figures: The bottom figure is a map of the Central Mediterranean Sea with sampled stations in coloured dots. The dashed green line indicates the NW-SE section used to display the eNd values represented in the figure above. Changes in eNd values may be ascribed to the presence of different water masses; for example, a tongue of radiogenic LIW is clearly delineated from its eastern origin to the western basin.

Reference:

Garcia-Solsona, E., Pena, L. D., Paredes, E., Pérez-Asensio, J. N., Quirós-Collazos, L., Lirer, F., & Cacho, I. (2020). Rare earth elements and Nd isotopes as tracers of modern ocean circulation in the central Mediterranean Sea. Progress in Oceanography, 185, 102340. DOI: https://doi.org/10.1016/J.POCEAN.2020.102340

Latest highlights

Substantial trace metal input from the 2022 Hunga Tonga-Hunga Ha’apai eruption into the South Pacific Ocean

Zhang and co-workers investigate the impact of the 2022 eruption on the biogeochemistry of the South Pacific Gyre.

Lead isotopes, reversible scavenging and ventilation processes in the South Atlantic Ocean

Olivelli and co-authors present seawater lead concentrations and lead isotopes for 10 depth profiles collected in the South Atlantic Ocean.

Iron limitation also affects the twilight zone

Li and co-workers established the distribution and uptake of siderophores along the Pacific meridional section (GP15 GEOTRACES cruise)…

Long distance dissolved iron transport in the North-East Pacific revealed by multiple tracers and an ocean circulation model

Sieber and co-authors have made extensive use of the multi-tracer approach, coupled to an oceanic circulation model…

Rechercher