Seasonal fluctuations in the chemistry of lime-stone springs: A possible means for characterizing carbonate aquifers

The dissolved carbonate species were analyzed in the waters of 14 carbonate springs in the Central Appalachians at 2-week intervals during water year 1967–1968. The springs were classified into diffuse-flow feeder-system types and conduit feeder-system types by hydrogeologic evidence. Comparison with the chemical parameters showed that the conduit springs were very variable in hardness throughout the year (coefficient of variation 10–24%) whereas the diffuse flow springs had a rather constant hardness (coefficient of variation \u3c5%). The variation in hardness is a better index of aquifer type than is hardness itself. Diffuse flow springs were, on the average near saturation; the conduit springs were undersaturated by factors of 2 to 5. Ca/Mg ratios were near unity for springs fed by dolomites or dolomite-related rocks; Ca/Mg ratios for limestone springs were 3–8 times higher. Aquifer systems of quite different flow mechanics can exist in the same hydrogeologic environment and can be distinguished by their chemical behavior