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Title: Long-term stability of organic carbon-stimulated chromatereduction in contaminated soils, and its relation to manganese redoxstatus

Abstract

In-situ reduction of toxic Cr(V1) to less hazardous Cr(II1)is becoming a popular strategy for remediating contaminated soils.However, the long term stability of reduced Cr remains to be understood,especially given the common presence of MnfIIIJV) oxides that reoxidizeCr(II1). This 4.6 year laboratory study tracked Cr and Mn redoxtransformations in soils contaminated with Cr(V1) which were then treatedwith different amounts of organic carbon (OC). Changes in Cr and Mnoxidation states within soils were directly and nondestructively measuredusing micro X-ray absorption near edge structure spectroscopy. Chromatereduction was roughly lst-order, and the extent of reduction was enhancedwith higher OC additions. However, significant Cr(||1) reoxidationoccurred in soils exposed to the highest Cr(V1) concentrations (2,560 mgkg"'). Transient Cr(II1) reoxidation up to 420 mg kg1 was measured at 1.1years after OC treatment, followed by further reduction. Chromateconcentrations increased by 220 mg kgm1a t the end of the study (4.6years) in one soil. The causal role that Mn oxidation state had inreoxidizing Cr was supported by trends in Mn K-edge energies. Theseresults provide strong evidence for longterm dependence of soil Croxidation states on balances between OC availability and Mn redoxstatus.

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
Sponsoring Org.:
USDOE Director. Office of Science. Basic EnergySciences
OSTI Identifier:
923420
Report Number(s):
LBNL-62676
Journal ID: ISSN 0013-936X; ESTHAG; R&D Project: 468211; BnR: KC0303020; TRN: US200804%%1119
DOE Contract Number:
DE-AC02-05CH11231
Resource Type:
Journal Article
Resource Relation:
Journal Name: Environmental Science and Technology; Journal Volume: 41; Journal Issue: 12; Related Information: Journal Publication Date: 2007
Country of Publication:
United States
Language:
English
Subject:
54; ABSORPTION; AVAILABILITY; CARBON; CHROMATES; MANGANESE; OXIDES; SOILS; SPECTROSCOPY; STABILITY; TRANSFORMATIONS; TRANSIENTS; VALENCE

Citation Formats

Tokunaga, Tetsu K., Wan, Jiamin, Lanzirotti, Antonio, Sutton,Steve R., Newville, Matthew, and Rao, William. Long-term stability of organic carbon-stimulated chromatereduction in contaminated soils, and its relation to manganese redoxstatus. United States: N. p., 2007. Web. doi:10.1021/es062874c.
Tokunaga, Tetsu K., Wan, Jiamin, Lanzirotti, Antonio, Sutton,Steve R., Newville, Matthew, & Rao, William. Long-term stability of organic carbon-stimulated chromatereduction in contaminated soils, and its relation to manganese redoxstatus. United States. doi:10.1021/es062874c.
Tokunaga, Tetsu K., Wan, Jiamin, Lanzirotti, Antonio, Sutton,Steve R., Newville, Matthew, and Rao, William. Tue . "Long-term stability of organic carbon-stimulated chromatereduction in contaminated soils, and its relation to manganese redoxstatus". United States. doi:10.1021/es062874c. https://www.osti.gov/servlets/purl/923420.
@article{osti_923420,
title = {Long-term stability of organic carbon-stimulated chromatereduction in contaminated soils, and its relation to manganese redoxstatus},
author = {Tokunaga, Tetsu K. and Wan, Jiamin and Lanzirotti, Antonio and Sutton,Steve R. and Newville, Matthew and Rao, William},
abstractNote = {In-situ reduction of toxic Cr(V1) to less hazardous Cr(II1)is becoming a popular strategy for remediating contaminated soils.However, the long term stability of reduced Cr remains to be understood,especially given the common presence of MnfIIIJV) oxides that reoxidizeCr(II1). This 4.6 year laboratory study tracked Cr and Mn redoxtransformations in soils contaminated with Cr(V1) which were then treatedwith different amounts of organic carbon (OC). Changes in Cr and Mnoxidation states within soils were directly and nondestructively measuredusing micro X-ray absorption near edge structure spectroscopy. Chromatereduction was roughly lst-order, and the extent of reduction was enhancedwith higher OC additions. However, significant Cr(||1) reoxidationoccurred in soils exposed to the highest Cr(V1) concentrations (2,560 mgkg"'). Transient Cr(II1) reoxidation up to 420 mg kg1 was measured at 1.1years after OC treatment, followed by further reduction. Chromateconcentrations increased by 220 mg kgm1a t the end of the study (4.6years) in one soil. The causal role that Mn oxidation state had inreoxidizing Cr was supported by trends in Mn K-edge energies. Theseresults provide strong evidence for longterm dependence of soil Croxidation states on balances between OC availability and Mn redoxstatus.},
doi = {10.1021/es062874c},
journal = {Environmental Science and Technology},
number = 12,
volume = 41,
place = {United States},
year = {Tue Mar 13 00:00:00 EDT 2007},
month = {Tue Mar 13 00:00:00 EDT 2007}
}