TEMPERATURE AND CONDUCTANCE AS PROXIES FOR ADDED SOLUTES DURING TRACER TESTS

Halides, such as chloride, bromide, and iodide, are commonly added as non-reactive solutes during tracer tests to characterize advection, dispersion, and reactions. However, real-time measurements of temperature and conductance may be accurate proxies for added non-reactive solutes and at a fraction of the cost. The goal of this study was to determine if temperature and conductance can be accurate proxies for added non-reactive solutes. Field tracer tests were conducted in an unconfined aquifer where iodide and pentafluoro benzoate were injected into a well and monitored in several down-gradient wells. The data for the added tracers, plus real-time temperature and conductance, in groundwater were analyzed for mass recovery, mean arrival time, and dispersion. Preliminary results suggested that real-time temperature and conductance can be accurate proxies for added solutes but are dependent on the magnitude of their differences between the injection and aquifer fluids.With further development, temperature and conductance could provide a practical and cost-effective approach to characterizing non-reactive solute transport.