Towards a cost-efficient method to apply anthropogenic gadolinium as a pseudo-natural tracer in monitoring waste water-derived xenobiotics in tap water

Anthropogenic Gd in the aquatic environment originates from very stable water-soluble Gd complexes used as contrast agents in magnetic resonance imaging (MRI). These contrast agents cannot be removed in waste water treatment plants and are released into surface waters with their clearwater discharge. Since the first discovery of anthropogenic Gd in tap water in Berlin in 1995, a strong increase was observed until 2012, mainly in the city’s western districts. For a follow-up study in 2021, we sampled these sites again to monitor evolving anthropogenic Gd levels in tap water over the past decade.

We adapted a method for automated preconcentration of seawater samples with low REY concentrations using a seaFAST system to the analysis of tap water. Comparing the results of this new protocol to those derived via the established manual method, we demonstrate the excellent agreement between these two approaches.

The general trend of strongly increasing anthropogenic Gd anomalies observed between 2009 and 2012 continued until 2021, closely following the increase of the number of MRI scans performed in Berlin. While the general spatial distribution confirms earlier observations of much stronger anthropogenic positive Gd anomalies in western than eastern districts, several eastern districts where no anthropogenic Gd had been observed in the past, now also show pronounced positive Gd anomalies, revealing the presence of waste water-derived xenobiotics in the tap water.

Using automated preconcentration for REY analysis in tap water, the microcontaminant Gd may now be applied as a reliable and cost-efficient pseudo-natural tracer for waste water-derived substances.