Alison R. Keimowitz

Adjunct Associate Research Scientist
Lamont-Doherty Earth Observatory
Geochemistry
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117 Comer
61 Route 9W - P.O. Box 1000
Palisades
NY
10964-8000
US
Fax: 
(845) 365-8155
Fields of interest: 
Controls on Arsenic Mobility in Contaminated Subsurface Environments

My research has focused on controls on arsenic mobility at two Superfund sites: the Vineland Chemical Company in Vineland, New Jersey and the Winthrop landfill in Winthrop, Maine. Although these sites are very different in terms of the source of arsenic (geogenic at Winthrop and anthropogenic at Vineland) and the scale of the remediation efforts (relatively modest at Winthrop and very large at Vineland), many of the mechanisms controlling the mobility of arsenic in the subsurface and therefore controlling the effectiveness of interventions are similar.

We have demonstrated that the arsenic in the groundwater at Winthrop is not anthropogenic and is released from the sediments beneath the closed landfill. Comparison of geochemical data from an upgradient and unaffected region with a region beneath the landfill has helped demonstrate that the trigger for arsenic release is the highly reducing state of the subsurface. These reducing conditions are induced by decay of landfill wastes into organic-rich landfill leachate that percolates into the aquifer below. Observations from a nearby swamp strengthen the conclusion that naturally-occurring arsenic is mobilized by reducing conditions at this site. Arsenic's ability to be mobilized by the reducing conditions typical within sub-landfill aquifers raises the possibility that this process could be occurring at many other landfill sites across the country and around the world.

Arsenic may also be immobilized under reducing conditions, when sulfate is reduced and insoluble iron and arsenic sulfides are formed. We have conducted a series of small-scale incubations of sediment and water under different conditions to induce sulfide mineral formation. In these experiments, addition of acetate promoted the growth of sulfate-reducing bacteria, thereby permitting the conversion of sulfate to sulfide and decreasing the concentrations of dissolved arsenic. Ongoing research is examining which components of the microbial community were responsible for these geochemical changes and which solid phases served as arsenic sinks. This laboratory research is a preliminary step in investigating an innovative remediation technique for removing arsenic (and potentially other redox-sensitive metals) from groundwater.

Education
List of degrees from highest to lowest:
B.A.
Wesleyan University
1997
M.S.
Yale University
2001
Ph.D.
Columbia University
2006
Honors & Awards: 
Received doctorate "with distinction," Columbia University 2006
Outstanding Student Paper Award, AGU Fall Meeting, Hydrology Division 2005
American Water Works Association's Larson Aquatic Research Support Scholarship 2004
Selected Publications: 
Laboratory investigations of enhanced sulfate reduction as a groundwater arsenic remediation strategy, Keimowitz, A. R.; Mailloux, B. J.; Cole, P.; Stute, M.; Simpson, H. J.; Chillrud, S. N. , Environmental Science & Technology, Oct 1, Volume 41, Issue 19, p.6718-6724, (2007), Doi 10.1021/Es061957q

Naturally occurring arsenic: Mobilization at a landfill in Maine and implications for remediation, Keimowitz, A. R.; Simpson, H. J.; Stute, M.; Datta, S.; Chillrud, S. N.; Ross, J.; Tsang, M. , Applied Geochemistry, Nov, Volume 20, Issue 11, p.1985-2002, (2005), DOI 10.1016/j.apgeochem.2005.06.008

Arsenic mobilization under reducing conditions beneath a landfill in Maine., Keimowitz, A. R.; Datta, S.; Stute, M.; Simpson, H. J.; Chillrud, S. N.; Tsang, M.; Ross, J. , Abstracts of Papers of the American Chemical Society, Sep, Volume 226, p.U584-U584, (2003)

Rotational spectra of argon acetone: A two-top internally rotating complex, Kang, L.; Keimowitz, A. R.; Munrow, M. R.; Novick, S. E. , Journal of Molecular Spectroscopy, Jun, Volume 213, Issue 2, p.122-129, (2002), DOI 10.1006/jmsp.2002.8551

QSAR analysis of Delta(8)-THC analogues: Relationship of side-chain conformation to cannabinoid receptor affinity and pharmacological potency, Keimowitz, A. R.; Martin, B. R.; Razdan, R. K.; Crocker, P. J.; Mascarella, S. W.; Thomas, B. F. , Journal of Medicinal Chemistry, Jan 13, Volume 43, Issue 1, p.59-70, (2000)