Rare Earth Elements are less and less natural tracers in the ocean

This verdict is well illustrated by the recent study of Rodrigo Pedreira (2018, see reference below) off the North East Brazilian coast. His Rare Earth Elements (REE) data reveal marked positive Gadolinium (Gd) anomaly which reflects the release of Gd in hospital and domestic effluents. Indeed, this element is used as contrasting agent in magnetic resonance imaging (MRI) to enhance clarity of diagnosis. The authors estimated that between 700 and 2000 g Gd d-1 are discharged into Tropical and South Atlantic waters due to submarine outfalls. While the Gd complex behaves conservatively and can be used as a new tracer for sewage discharges from submarine outfalls in ocean waters, it is also clear that high technology wastes are distorting the use of REE as “natural” tracers.

 GEOTRACES Highlights Opcao2 HR

Figure: Sampling took place (a) off the northeastern coast of Brazil, whereas discharges of submarine outfalls located along the coast of Brazil (a insert) were used to estimate order-of-magnitude emissions of anthropogenic Gd to the Atlantic Ocean. A plume of Gd anomalies (Gdsn/Gdsn*) can be clearly identified for surface waters (b). Positive Gd anthropogenic anomalies are observed in shale (PAAS)-normalized REE patterns (c) for surface waters (S) in most stations in the proximity of submarine outfalls (ERVS and EBVS). Click here to view the figure larger.


Pedreira, R. M. A., Pahnke, K., Böning, P., & Hatje, V. (2018). Tracking hospital effluent-derived gadolinium in Atlantic coastal waters off Brazil. Water Research, 145, 62–72. DOI : http://doi.org/10.1016/j.watres.2018.08.005

Latest highlights

Science Highlights

A new proxy for ocean iron bioavailability

The approach established and verified in this study, opens a new way for determining dissolved iron bioavailability in samples across the ocean.


Science Highlights

Scavenging differentiates the distribution of cadmium, nickel, zinc and copper in the North Pacific Ocean

Zheng and co-authors observed sectional distributions of cadmium, nickel, zinc, and copper in the North Pacific Ocean during three GEOTRACES related cruises…


Science Highlights

Surprising conservativity of trace metals along a costal embayment salinity gradient

Chen and co-workers analyzed an array of trace metals together with Rare Earth Elements in a salinity gradient in the Jinhae Bay, the largest semi-enclosed bay in South Korea…


Science Highlights

Measuring actinium-227 by mass spectrometry is feasible, sensitive and reliable!

Levier and co-authors have developed a new protocol measurement of the dissolved actinium in seawater.