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Threshold amounts of organic carbon needed to initiate reductive dechlorination in groundwater systems

Remediation

By:
, , , ,
DOI: 10.1002/rem.21318

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Abstract

Aquifer sediment and groundwater chemistry data from 15 Department of Defense facilities located throughout the United States were collected and analyzed with the goal of estimating the amount of natural organic carbon needed to initiate reductive dechlorination in groundwater systems. Aquifer sediments were analyzed for hydroxylamine and NaOH-extractable organic carbon, yielding a probable underestimate of potentially bioavailable organic carbon (PBOC). Aquifer sediments were also analyzed for total organic carbon (TOC) using an elemental combustion analyzer, yielding a probable overestimate of bioavailable carbon. Concentrations of PBOC correlated linearly with TOC with a slope near one. However, concentrations of PBOC were consistently five to ten times lower than TOC. When mean concentrations of dissolved oxygen observed at each site were plotted versus PBOC, it showed that anoxic conditions were initiated at approximately 200 mg/kg of PBOC. Similarly, the accumulation of reductive dechlorination daughter products relative to parent compounds increased at a PBOC concentration of approximately 200 mg/kg. Concentrations of total hydrolysable amino acids (THAA) in sediments also increased at approximately 200 mg/kg, and bioassays showed that sediment CO2 production correlated positively with THAA. The results of this study provide an estimate for threshold amounts of bioavailable carbon present in aquifer sediments (approximately 200 mg/kg of PBOC; approximately 1,000 to 2,000 mg/kg of TOC) needed to support reductive dechlorination in groundwater systems.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Threshold amounts of organic carbon needed to initiate reductive dechlorination in groundwater systems
Series title:
Remediation
DOI:
10.1002/rem.21318
Volume
22
Issue:
3
Year Published:
2012
Language:
English
Publisher:
Wiley Periodicals, Inc.
Publisher location:
Hoboken, NJ
Contributing office(s):
South Carolina Water Science Center
Description:
10 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
19
Last page:
28
Number of Pages:
10
Country:
United States