An evaluation of ground‐water tracers

Abstract

The ideal ground‐water tracer should correctly depict the movement of water through a porous medium without modifying the transmission characteristics of the system. Cationic materials, including radio‐isotopes and certain organic dyes, are generally unsatisfactory and anionic radio‐isotopes when used without stable carriers may be largely retained by adsorption. Chloride may be satisfactorly used where density effects can be avoided and dispersion of clays is not likely. Organic materials are subject to decomposition by soil microorganisms and hence their value as water tracers are limited. Tritium, when used as tritiated water, may exchange with soil bound water with a resulting reduction in velocity of the tracer front.