Laboratory investigations of enhanced sulfate reduction as a groundwater arsenic remediation strategy

Publication Type  Journal Article
Year of Publication  2007
Authors  Keimowitz, A. R.; Mailloux, B. J.; Cole, P.; Stute, M.; Simpson, H. J.; Chillrud, S. N.
Journal Title  Environmental Science & Technology
Volume  41
Issue  19
Pages  6718-6724
Journal Date  Oct 1
ISBN Number  0013-936X
Accession Number  ISI:000249840600018
Key Words  bangladesh groundwater; reducing conditions; natural-waters; fe release; iron; sulfide; speciation; sediments; sorption; precipitation

Landfills have the potential to mobilize arsenic via induction of reducing conditions in groundwater and subsequent desorption from or dissolution of arsenic-bearing iron phases. Laboratory incubation experiments were conducted with materials from a landfill where such processes are occurring. These experiments explored the potential for induced sulfate reduction to immobilize dissolved arsenic in situ. The native microbial community at this site reduced sulfate in the presence of added acetate. Acetate respiration and sulfate reduction were observed concurrent with dissolved iron concentrations initially increasing from 0.6 mu M (0.03 mg L-1) to a maximum of 111 mu M (6.1 mg L-1) and subsequently decreasing to 0.74 mu M (0.04 mg L-1). Dissolved arsenic concentrations initially covaried with iron but subsequently increased again as sulfide accumulated, consistent with the formation of soluble thioarsenite complexes. Dissolved arsenic concentrations subsequently decreased again from a maximum of 2 mu M (148 mu g L-1) to 0.3 mu M (22 mu g L-1), consistent with formation of sulfide mineral phases or increased arsenic sorption at higher pH values. Disequilibrium processes may also explain this second arsenic peak. The maximum iron and arsenic concentrations observed in the lab represent conditions most equivalent to the in situ conditions. These findings indicate that enhanced sulfate reduction merits further study as a potential in situ groundwater arsenic remediation strategy at landfills and other sites with elevated arsenic in reducing groundwater.


215WVTimes Cited:0Cited References Count:44

URL  <Go to ISI>://000249840600018
DOI  Doi 10.1021/Es061957q