Although great strides have been made towards understanding REE geochemical behavior in marine environment, considerably less effort has been directed towards the studies of geochemical behavior of REEs in natural terrestrial waters. This monograph, therefore, first develops an easily employed predictive tool for REE complexation with both inorganic and organic ligands in natural water using a well known metal-organic matter speciation code (Humic Ion-Binding Model V). Then, this monograph studies the concentrations, fractionation patterns, and speciation of REEs along groundwater ...