Application of strontium isotopes for tracing landfill leachate plumes in groundwater

We are evaluating strontium isotopes as alternative tracers of landfill lea chate in groundwater. The municipal landfill studied here is located in sou theastern France. This landfill has no bottom liner, and wastes are placed directly on the ground. Based on the evaluation of chloride concentration, the plume extends a maximum of 4600 m. Strontium isotopic composition chara cterizes two sources: natural groundwater (Sr-87/Sr-86 = 0.708175) and land fill leachate contamination (Sr-87/Sr-86 = 0.708457). The evolution of mixi ng ratios obtained with strontium reveals a second source of groundwater co ntamination: fertilizers (Sr-87/Sr-86 = 0.707859). These results suggest th at isotopic signatures can be used to provide useful information on sources of groundwater contamination where conventional water quality parameters m ay yield ambiguous results.