Relation between Gd anomalies and perfluorinated compounds in surface and ground waters: case study of the Romagna area (Italy)

Perfluorinated compounds (PFAS) are bioaccumulative and biologically harmful substances. They enter the environment as a consequence of the incorrect disposal of effluents coming from wastewater treatment plants, not always... [ view full abstract ]

Perfluorinated compounds (PFAS) are bioaccumulative and biologically harmful substances. They enter the environment as a consequence of the incorrect disposal of effluents coming from wastewater treatment plants, not always efficient in removing such microcontaminants. Gadolinium, one of the rare earth elements group used as contrast agent in magnetic resonance imaging, is a good conservative tracer of wastewater effluents, being stable in aquatic systems once released in the environment. This study aims to assess the degree of contamination by PFAS on the main river bodies and confined aquifers of the Romagna area (Italy), using Gd as tracer. Samples taken at the entrance and exit of two drinking water treatment plants were also analysed. PFAS detection was carried out with LC-MS/MS technique. Among the analysed PFAS, only PFOA reports concentrations above the detection limit in approximately 50% of total samples. Rivers on the northern part of the study area show an anthropogenic enrichment of Gd relative to its geogenic concentration, with values up to 10 times higher than the geogenic expected value. The southern portion of the area, as well as samples coming from confined aquifers, do not show any Gd anomaly. PFOA displays a similar distribution pattern, with higher values concentrated in the final stretch of the northern rivers, in proximity of hospital and wastewater treatment plants. The statistically significant correlation (α=0.05) between the two compounds demonstrates a similar input in the aquatic environment. The two drinking water treatment plants are not completely efficient in removing PFOA from contaminated waters.