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

Abstract

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 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.

Evaluation of water quality in surface water and shallow groundwater: a case study of a rare earth mining area in southern Jiangxi Province, China

“…The negative Ce anomalies are expected to be highly controlled by the redox conditions. The negative Ce anomaly only occurred when Fe, Mn, and dissolved organic carbon (DOC) concentrations were low (Fe and Mn<5×10 −5 and DOC<10 mol L −1 ) (Seto and Akagi 2008). When Ce was exposed to high redox potential (Eh) conditions, part of the Ce(III) was likely to be oxidized to Ce(IV).…”

Geochemistry of REE, Zr and Hf in a wide range of pH and water composition: The Nevado del Ruiz volcano-hydrothermal system (Colombia)

“…Cerium and Europium differ from the other REE for being redox sensitive elements. Cerium is removed from waters during neutralization as CeO 2 and/or from precipitation of Fe, Mn and Al oxyhydroxides in river waters and marine environment (Goldstein and Jacobsen, 1988;Elderfield et al, 1990;Seto and Tsaku, 2008). The Ce and Eu anomalies vary with pH (Fig.…”

Zirconium–hafnium and rare earth element signatures discriminating the effect of atmospheric fallout from hydrothermal input in volcanic lake water

“…Cerium is sensitive to redox changes and easily removed from solution as CeO 2 and/or by adsorption onto Mn-and Fe-oxyhydroxide under oxidizing conditions (Bau, 1999;Seto and Tsaku, 2008;Bau and Koschinsky, 2009 and references therein). A strong positive Ce anomaly was found in the lake water, quite different from the hydrothermal waters.…”