Dense Nonaqueous Phase Liquids (DNAPLs)Chromium VI
Dense Nonaqueous Phase Liquids (DNAPLs)
1,4-Dioxane
Mercury
MTBE
Perchlorate
POPs
PCBs
TCE
Other Contaminants
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Detection and Site Characterization
Tracers
Radon-222 as Natural Tracer for Monitoring the Remediation of NAPL Contamination in the Subsurface: Cost and Performance Report
Environmental Security Technology Certification Program, ESTCP Project ER-9916, 71 pp, 2008
This report describes the use of naturally occurring radon-222 as a partitioning tracer for locating and quantifying residual or pooled NAPL (e.g., chlorinated solvent) contamination in the subsurface and for monitoring changes in NAPL quantities resulting from remediation activities. The method is based on measuring radon in ground-water samples from existing monitoring wells. Two methods of using radon were evaluated at Dover National Test Site: a static method that involves the monitoring of NAPL concentrations in ground-water samples collected spatially and temporally at a site, and a dynamic method using single well push-pull tests. The most cost-effective use of the method is for monitoring the progress of NAPL contamination using the static method where ground-water samples are periodically collected and changes in radon concentration are monitored at a specific location over time.
Abstracts of Journal Articles
Influence of Residual Surfactants on DNAPL Characterization Using Partitioning Tracers
Cho, Jaehyun and Michael D. Annable (Univ. of Florida, Gainesville); P. Suresh C. Rao (Purdue Univ., West Lafayette, IN). Journal of Contaminant Hydrology, Vol 72 Nos 1-4, p 67-83, Aug 2004
Via the partitioning tracer technique, researchers examined in batch and column experiments the magnitude of artifacts introduced in estimating DNAPL content when residual surfactants used for in situ flushing are present. Batch equilibrium tests using residual surfactants ranging from 0.05 to 0.5 wt.% showed that as the surfactant concentrations increased, the tracer partition coefficients decreased linearly for sodium hexadecyl diphenyl oxide disulfonate (DowFax 8390), increased linearly for polyoxyethylene (10) oleyl ether (Brij 97), and decreased slightly or exhibited no observable trend for sodium dihexyl sulfosuccinate (AMA 80). Results from column tests using clean sand with residual DowFax 8390 and tetrachloroethene (PCE) were consistent with those of batch tests. In the presence of DowFax 8390 (less than 0.5 wt.%), the PCE saturations were underestimated by up to 20%. Adsorbed surfactants on a loamy sand with positively charged oxides showed false indications of PCE saturation based on partitioning tracers in the absence of PCE. Soil without surfactant (background soil) gave a false PCE saturation of 0.0004, while soil contacted by AMA 80, Brij 97, and DowFax 8390 presented false PCE saturations of 0.0024, 0.043, and 0.23, respectively.
Practical Applications of Tracers in Environmental Hydrogeology and Groundwater Remediation
Divine, Craig E., ARCADIS, Highlands Ranch, CO. Geological Society of America 2004 Denver Annual Meeting (November 7-10, 2004), Abstracts with Programs, Vol 36 No 5, p 395, 2004
Applied tracers have been widely used to characterize groundwater flowpaths and estimate velocities, particularly in karst regions. Advances in chemical measurement technology have led to a significant increase in the diversity of constituents used as tracers, permitted quantification of significantly lower tracer breakthrough concentrations, and made high-frequency sampling economically feasible. Consequently, the practical (i.e., non-research) use of tracers in environmental hydrogeology and groundwater remediation is quickly increasing. For example, the spatial distribution of basic aquifer information can be inexpensively obtained using simple single-well tracer tests. Conservative and reactive tracers can greatly aid in the design and evaluation of enhanced bioremediation strategies by providing a reliable way to measure in situ contaminant decay, electron acceptor/donor utilization rates, and zones of influence. The long-term application of tracers can used to evaluate hydraulic capture and demonstrate containment. For some high-priority sites, phase-partitioning tracers can be used to quantify subsurface volume of nonaqueous phase liquid (NAPL) in support of targeted NAPL-zone remediation activities. This presentation contains several case studies and discussions of other potential practical applications of tracers in environmental hydrogeology and groundwater remediation.
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Last updated on Thursday, July 24, 2008