Using Natural Isotopes for the Environmental Tracking of a Controlled Landfill Site for Non-Hazardous Waste in Liguria, Italy

: The application of natural radioisotope and stable isotope tracing represents a novel, sensitive method for confirming the presence of environmental contamination due to leachate water from solid waste landfills. This study aimed to employ this approach to assess the efficiency of containment measures and the potential environmental impact in the vicinity of a landfill designated for non-hazardous waste disposal. We collected leachate water samples from two distinct areas: one currently active, and another exhausted. In February, May, August, and November 2022, we collected deep water samples from a nearby stream utilizing piezometers, both upstream and downstream from the facility. We examined deuterium and tritium radioisotopes via liquid scintillation, and stable isotope oxygen-18 via ratio mass spectrometry. The results revealed the presence of anthropogenic radioisotopes within the landfill, with higher concentrations in the active site. No radioisotopes or stable isotopes above the natural background were identified in any of the samples obtained from outside. The levels of tritium were found to correlate with rainfall in the samples collected inside, but not in those obtained outside. These findings provide evidence of the effectiveness of the active structural, managerial, and procedural containment measures and the absence of environmental contamination stemming from the studied site, reinforcing the value of the responsible management of non-hazardous waste and its limited impact on the surrounding environment. The reported results highlight the utility of performing radioisotope and stable isotope monitoring not only inside but also outside the landfill, and analyzing the relation via pluviometry.