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Behavior of Chromium in Soils: II. Hexavalent Forms
Author(s) -
Bartlett R. J.,
Kimble J. M.
Publication year - 1976
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1976.00472425000500040010x
Subject(s) - chemistry , soil water , organic matter , hexavalent chromium , adsorption , environmental chemistry , manure , solubility , chromium , soil organic matter , clay minerals , mineralogy , soil science , agronomy , organic chemistry , geology , biology
Adsorption and reduction of added Cr(VI) were characterized in soils with contrasting pH's, organic matter contents, and chemical and mineralogical properties. Presence of soil organic matter brought about spontaneous reduction of Cr(VI) to Cr(III), even at pH's above neutrality. Reduction did not occur in soils very low in organic matter unless an energy source was added. Cow manure added to practically organic‐free Cecil B2 reduced Cr(IV) only after the pH had been lowered below 3 with HCl. The solubility of Cr(VI) in the presence of excess Al changed in a pattern remindful of orthophosphate. All of the soils, except a pH 7.8 Cca horizon material, adsorbed Cr(VI). Presence of orthophosphate prevented the adsorption of Cr(VI), presumably by competition for the adsorption sites. Consistent with this finding, KH 2 PO 4 was found to be the best extracting agent for Cr(VI). It was concluded that behavior of Cr(VI), if it remains in soils, is similar to that of orthophosphate. However, unlike phosphate, Cr(VI) is quickly reduced by soil organic matter. Thus, Cr(VI) added to a soil will remain mobile only if its concentration exceeds both the adsorbing and the reducing capacities of the soil.