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RESEARCH ARTICLE
Contents Vol 3(3)

Comparative Analysis of Soluble Phosphate Amendments for the Remediation of Heavy Metal Contaminants: Effect on Sediment Hydraulic Conductivity

Dawn M. Wellman A B , Jonathan P. Icenhower A and Antoinette T. Owen A
+ Author Affiliations
- Author Affiliations

A Pacific Northwest National Laboratory, 902 Battelle Blvd, PO Box 999, MS K6-81, Richland, WA 99352, USA.

B Corresponding author. Email: dawn.wellman@pnl.gov

Environmental Chemistry 3(3) 219-224 https://doi.org/10.1071/EN05023
Submitted: 15 April 2005  Accepted: 28 April 2006   Published: 10 July 2006

Environmental Context. The contamination of surface and subsurface geologic media by heavy metals and radionuclides is a significant problem within the United States Department of Energy complex as a result of past nuclear operations. Water-soluble phosphate compounds provide a means to inject phosphorus into subsurface contaminant plumes, to precipitate metal ions from solution. However, phosphate phases can form within the sedimentary pore structure to block a fraction of the pore space and inhibit further remediation of the contaminant plume. A series of tests have been conducted to evaluate changes in sedimentary pore structure during the application of several proposed phosphate remediation amendments.

Abstract. A series of conventional, saturated column experiments have been conducted to evaluate the effect of utilizing in situ, soluble, phosphate amendments for subsurface metal remediation on sediment hydraulic conductivity. Experiments have been conducted under mildly alkaline and calcareous conditions representative of conditions commonly encountered at sites across the arid western United States, which have been used in weapons and fuel production and display significant subsurface contamination. Results indicate that the displacement of a single pore volume of either sodium monophosphate or phytic acid amendments causes approximately a 30% decrease in the hydraulic conductivity of the sediment. Long-chain polyphosphate amendments afford no measurable reduction in hydraulic conductivity. These results demonstrate (1) the efficacy of long-chain polyphosphate amendments for subsurface metal sequestration; and (2) the necessity of conducting dynamic experiments to evaluate the effects of subsurface remediation.

Keywords. : geochemistry — hydraulic conductivity — sediments — water treatment — XMT [X-ray microtomography]


Acknowledgements

This work was conducted at Pacific Northwest National Laboratory operated by Battelle for the U.S. Department of Energy under Contract DE-AC05-76RL01830.


References


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