Can Chromatography Occur in Nature?

Adsorption of calcium and magnesium on a sandstone from a bicarbonate solution has been demonstrated. On elution with water saturated with carbon dioxide, the magnesium passes off first. The chromatographic separation of magnesium from calcium can thus occur under conditions which can prevail in nature. We ask: Does chromatography play a part in geochemistry? More specifically we ask: Can calcium and magnesium be separated by the chromatographic process on sandstone? Eyen more specifically: Can such a separation be demonstrated in the laboratory on a natural sandstone under conditions which can occur in nature? The answers to all three questions appear to be yes. For the demonstration we selected sandstone from the Chugwater and Tensleep formations of north central Wyoming. A 1 Department of Chemistry, Iowa State Univexsity, Ames, Iowa 1 Kemp and Diehl: Can Chromatography Occur in Nature? Published by UNI ScholarWorks, 1965 1965] SEPARATION OF MAGNESIUM FROM CALCIUM 151 solution containing calcium and magnesium bicarbonates was passed through the sandstone and the adsorbed calcium and magnesium eluted with water containing dissolved carbon dioxide. Suitable chemical analyses were made to show that calcium and magnesium were adsorbed and subsequently eluted and that differences exist in the behavior of calcium and magnesium during adsorption and elution, that calcium is the more firmly held to the sandstone. Greatest success was achieved with crushed Tensleep sandstone. Given an extended time to accomod~te the slow percolation of water through the uncrushed sandstone, quite conceivably the same behavior and separation could occur under circumstances which may very easily prevail in nature.