Anthropogenic Gadolinium and Other Emerging Contaminants in the Southern North Sea and the Elbe, Ems and Weser Estuaries

In the last decades, many trace elements that were hitherto only used as geochemical proxies gained societal and economic importance due to their increasing use in high-technology applications including medicine and renewable energies. The increasing application of such metals results in a tremendously growing and unconstrained input from anthropogenic sources into the environment. Knowledge of the environmental behavior and the toxicity of these compounds are for many of these elements still in their infancy. The minute concentrations in the natural environment and complex matrices pose additional analytical challenges.

This contribution presents results on the anthropogenic and geogenic inputs of gadolinium, a major component in MRI contrast agents, and other emerging contaminants into the southern North Sea from the Elbe, Ems and Weser estuaries. The water samples were collected during research cruise M169 “TRAM” (“Tracing geogenic and anthropogenic critical high-technology metals in the southern North Sea”) with R/V Meteor.

Using Seafast-QQQ-ICPMS, we provide evidence for the widespread anthropogenic input/distribution of the wastewater-derived contaminant Gd in the southern North Sea, including the Wadden Sea World Heritage. Complementary ultrafiltration and DGT passive sampling data show that the anthropogenic Gd exclusively occurs in the truly dissolved element pool (< 1KDa) of the discharged river waters and is bound in a highly stable, inert complex that is not bioavailable. Our results corroborate the notion that the Gd-based contrast agents used during MRI scans may pass wastewater treatment plants unhindered and show a very conservative behavior during estuarine mixing, enabling its transport to the open sea.