You are here:
IN-SITU REMEDIATION OF CHROMIUM-CONTAMINATED SOILS AND SEDIMENTS USING SODIUM DITHIONITE
Citation:
Paul*, C J., F A. Khan*, AND R W. Puls*. IN-SITU REMEDIATION OF CHROMIUM-CONTAMINATED SOILS AND SEDIMENTS USING SODIUM DITHIONITE. GWPC Annual Forum, Reno, NV, 09/22-26/2001.
Description:
Soil cores were collected from beneath an old chrome plating shop at the USCG Support Center near Elizabeth City, NC in order to determine the extent of chromium contamination in the soils and ground water. Selective extractions were used to assess the chemical speciation and distribution of the chromium on the soils and its mobilization potential. Laboratory studies were also conducted to evaluate three liquid reductants (sodium dithionite, 1-ascorbic acid, and free hydroxylamine) to determine their ability to detoxify and immobilize chromate in situ. Sodium dithionite proved to be the most effective at reducing Cr(VI) to Cr(III) with the least side effects. In July 1999, a field scale pilot study was conducted using sodium dithionite to evaluate the effectiveness of reducing Cr(VI) in situ at the site. Results showed aqueous chromate concentrations decreased from up to 5 mg/L to <0.01 mg/L in all wells within the one meter cylindrical zone of influence of the test. Cr(VI) reduction was still seen at 48 weeks post-injection, indicating that long-term reduction was occurring. Analyses of post-injection sediment cores indicated that non-mobile reduced structural iron within the silicate minerals present in the treated sediments may contribute to long-term remediation of Cr(VI).