Chemical condition for the appearance of a negative Ce anomaly in stream waters and groundwaters

MAYUMI SETO, TASUKU AKAGI
2008 Geochemical Journal  
Nine publications showing REE data in groundwaters and river water were examined to understand the general condition of terrestrial water where a negative Ce anomaly develops. It was found that the negative Ce anomaly only appeared when Fe, Mn and dissolved organic carbon (DOC) concentrations were low (Fe and Mn < 5 × 10 -5 mol/L and DOC < 10 mg/L). Assuming that Ce 3+ and Fe 2+ concentrations were limited by the formation of cerianite and ferrihydrite, respective redox potential (Eh) was
more » ... tial (Eh) was calculated from each of Ce 3+ and Fe 2+ concentrations. For data sets displaying Ce anomalies, the calculated Ehs (cEhs) showed a 1:1 relationship between Ce and Fe. This relationship indicates that the absolute concentration of Ce in natural water may be thermodynamically determined in situ by Eh and pH when concentrations of Fe, Mn and DOC are poor.
doi:10.2343/geochemj.42.371 fatcat:lsrhmjd4ynbebplwtf2p2zcufq