Strontium Isotope as Tracers of Groundwater Contamination

Groundwater flowing under a municipal solid waste landfill has been studied to identify potential contamination phenomenon and to test strontium isotopic composition as a natural tracer of contamination. The study was carried on in June 2014 in central Italy. Five selected boreholes were selected and analysed according to their location related to the site. Samples taken from boreholes placed upward to the site were considered as uncontaminated groundwater. One borehole located downward from the site and with major contaminant values has been considered as potentially contaminated end-member. Sr isotope results show that samples located upward from the site present lower Sr concentration and highest Sr isotopic values, which reflects weathered bedrock, while borehole located downward from the site show lowest Sr values and 87Sr/86Sr ratio, probably due to pollution by landfill leachate. The mixing calculation highlights the possible mixing phenomenon for the other samples located downward from the site.