Laboratory and field scale evaluation of geochemical controls on groundwater transport of nitroaromatic ammunition residues
- Swiss Federal Inst. of Technology, Duebendorf (Switzerland)
- Dresdner Grundwasserforschungszentrum e.V., Dresden (Germany)
Sorption to soils and sediments of nitroaromatic explosives may be due to interactions with natural organic matter (NOM) or complex formation with clays, which strongly depends on the type of exchangeable cations, i.e., the base saturation of the clays. The authors examined the relative importance of these two processes for NAC sorption at aquifer material and evaluated the potential of decreasing or enhancing the mobility of NACs in contaminated aquifers by stimulated cation exchange. Generally, sorption on NOM of 2,4,6-trinitrotoluene (TNT) and related nitroaromatic compounds (NACs) was low compared to sorption at clays, and no evidence for specific interactions with NOM was found. Adsorbed NOM hardly affected the complex formation of NACs with clays. NAC sorption at pure clays and at aquifer material depended on the K[sup +]-saturation of these materials. Typical aquifer material containing [le]1% NOM and 3-5% clays exhibited similar sorption features than pure clay minerals, suggesting that NAC sorption to the bulk aquifer matrix was dominated by complex formation with clays. They applied these laboratory findings in a two-step field test designed to control the groundwater transport of NACs by the injection of electrolytes. 4-Nitrotoluene (4-NT) and KCI were injected into a sandy aquifer, and their groundwater transport was monitored at an extraction well. Subsequent injection of CaCl[sub 2] remobilized the previously adsorbed 4-NT due to ion exchange of Ca[sup 2+] for K[sup +] at clays present in the aquifer matrix. The susceptibility of NAC sorption to the composition of exchangeable cations at clays was confirmed for TNT and related NACs. Controlling the base saturation of the aquifer matrix by electrolyte injections thus opens new perspectives for gentle remediation of sites contaminated with nitroaromatic explosives.
- OSTI ID:
- 6299142
- Journal Information:
- Environmental Science and Technology, Vol. 33:15; ISSN 0013-936X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE
BENCH-SCALE EXPERIMENTS
ENVIRONMENTAL TRANSPORT
FIELD TESTS
GEOCHEMISTRY
GROUND WATER
NITRO COMPOUNDS
REMEDIAL ACTION
RESIDUES
TNT
WATER POLLUTION
CHEMICAL EXPLOSIVES
CHEMISTRY
EXPLOSIVES
HYDROGEN COMPOUNDS
MASS TRANSFER
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
POLLUTION
TESTING
WATER
540220* - Environment
Terrestrial- Chemicals Monitoring & Transport- (1990-)
450100 - Military Technology
Weaponry
& National Defense- Chemical Explosions & Explosives