Dense Nonaqueous Phase Liquids (DNAPLs)Chromium VI
Dense Nonaqueous Phase Liquids (DNAPLs)
1,4-Dioxane
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Detection and Site Characterization
Halogenated Alkenes
Cohen and Mercer (1993) identified seven chlorinated alkenes commonly found in the environment. Five are solvents or degradation products, and two are pesticides (cis-1,3-dichloropropene and trans-1,3-dichloropropene). The chlorinated ethenes are the organic contaminants most commonly found at Superfund sites. These chemicals have properties that are typical of volatile organic compounds (VOCs) and hence can be detected by most methods that detect and analyze VOCs. Methods such as vertical profiling, membrane interface probe, hydrophobic flexible membranes and dyes, and GC/MS appear in the main part of this section. Below are studies and analytical methods specific to halogenated ethenes.
| Halogenated Alkenes |
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| 1,1-Dichloroethene cis-1,2-Dichloroethene trans-1,2-Dichloroethene cis-1,3-Dichloropropene trans-1,3-Dichloropropene Tetrachloroethene Trichloroethene |
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Characterization |
Standard Laboratory Methods |
Field Screening Methods
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Diffusion Samplers for Groundwater Profiling
Although several different types of diffusion bag samplers exist, most operate on the premise of obtaining a concentration equilibrium between the water outside and the water or air inside the bag. In DNAPL investigations, they can be particularly useful in obtaining a vertical profile of the aquifer by identifying concentration gradients that in turn may be used to estimate source zone architecture. Diffusion samplers are effective for collecting both chlorinated ethenes and the dichloropropenes.
Assessment of Subsurface Chlorinated Solvent Contamination Using Tree Cores at the Front Street Site and a Former Dry Cleaning Facility at the Riverfront Superfund Site, New Haven, Missouri, 1999-2003
J.G. Schumacher, G.C. Struckhoff, and J.G. Burken.
U.S. Geological Survey Scientific Investigations Report 2004-5049, 41 pp, 2004
This report presents the results of tree-core sampling used to determine the presence and extent of chlorinated solvent contamination at two sites—the Front Street site (operable unit OU1) and the former dry cleaning facility--which are part of the overall Riverfront Superfund Site. Traditional soil and groundwater sampling at these two sites later confirmed the results from the tree-core sampling. Results obtained from the tree-core sampling were used to design and focus subsequent soil and groundwater investigations, resulting in substantial savings in time and site assessment costs.
Field Demonstration and Validation of a New Device for Measuring Water and Solute Fluxes, NASA LC-34 Site
Environmental Security Technology Certification Program (ESTCP), 172 pp, 2006
ESTCP passive flux meter (PFM) demonstration and validation projects include MTBE flux measurement at Port Hueneme, perchlorate flux at the Naval Surface Warfare Center at Indianhead, and trichloroethene (TCE) flux at NASA Launch Complex 34 at Cape Canaveral.
Real-Time and Delayed Analysis of Tree and Shrub Cores as Indicators of Subsurface Volatile Organic Compound Contamination, Durham Meadows Superfund Site, Durham, Connecticut, August 29, 2006
Vroblesky, D.A., R.E. Willey, S. Clifford, and J.J. Murphy.
U.S. Geological Survey Scientific Investigations Report 2007-5212, 12 pp, Feb 2008
The authors examined VOC concentrations in cores from trees and shrubs for use as indicators of vadose-zone contamination or potential VOC vapor intrusion into buildings. The study used real-time tree- and shrub-core analysis, which involved field heating the core samples for 5 to 10 minutes prior to field analysis, as well as delayed analysis, which involved allowing the gases in the cores to equilibrate with the headspace gas in the sample vials unheated for 1 to 2 days prior to analysis. General correspondence was found between the two approaches, indicating that preheating and field analysis of vegetation cores is a viable approach to real-time monitoring of subsurface VOCs. Thus, the methods may have application for determining the potential for vapor intrusion into buildings.
User's Guide to the Collection and Analysis of Tree Cores to Assess the Distribution of Subsurface Volatile Organic Compounds
D.A. Vroblesky.
U.S. Geological Survey Scientific Investigations Report 2008-5088, 59 pp, 2008
Method 8021B is used to determine volatile organic compounds in a variety of solid waste matrices. This method is applicable to nearly all types of samples, regardless of water content, including groundwater, aqueous sludges, caustic liquors, acid liquors, waste solvents, oily wastes, mousses, tars, fibrous wastes, polymeric emulsions, filter cakes, spent carbons, spent catalysts, soils, and sediments. If the gas chromatograph (GC) used does not employ two columns with different retention characteristics, the chemical identification will be tentative unless the site only contains the chemical of interest. The ECD detector is preferred when chlorinated chemicals are of interest.
Method 8121: Chlorinated Hydrocarbons by Gas Chromatography: Capillary Column Technique
Method 8121 describes the determination of chlorinated hydrocarbons in extracts prepared from environmental samples and RCRA wastes. It describes wide-bore open-tubular, capillary column GC procedures using both single-column/single-detector and dual-column/dual-detector approaches. If the GC does not employ two columns with different retention characteristics the chemical identification will be tentative unless the site contains only the chemical of interest.
Color-Tec® is a field-based analytical method that combines colorimetric gas detector tubes with sample purging to detect very low (to <2 µg/L) concentrations of chlorinated volatile organic halocarbons in liquid and solid samples. AQR's Color-Tec® method provides fast, low-level, economical, decision-quality data, which maximizes sampling frequency and sample coverage to locate source zones and delineate dissolve-phase contaminant plumes. Samples are analyzed by using a hand-operated vacuum pump to purge the volatile compounds from a groundwater or soil sample through the colorimetric tube, which is designed to produce a distinct color change when exposed to chlorinated compounds. The method detection limit is best with higher chlorinated compounds, such as PCE.
This method uses direct sampling ion trap mass spectrometry (DSITMS) for rapid quantitative measurement, continuous real-time monitoring, and qualitative and quantitative preliminary screening of VOCs in water, soil, soil gas, and air. DSITMS introduces sample materials directly into an ion trap mass spectrometer by means of a simple interface, such as a capillary restrictor. There is little if any sample preparation and no chromatographic separation. The response of the instrument to analytes in a sample is nearly instantaneous. In addition, the instrument is field transportable, rugged, and relatively easy to operate and maintain. Due to the absence of chromatographic separation, positive identification of analytes can be problematic in complex mixtures.
Method 8535 (Proposed): Screening Procedure for Total Volatile Organic Halides in Water
This colorimetric procedure to screen water samples for volatile halogenated organic compounds employs a commercially-available testing product. The method is not specific for any one halogenated compound.
Negative Ion Sensors for Real-Time Downhole DNAPLs Detection
G.D. Gillispie.
AFRL-ML-TY-TR-2002-4517, 107 pp, 2002
The haloprobe functions by converting halogenated molecules into water, carbon dioxide, and halogen ions. The halogen ions are counted and used to estimate the original molecule's concentration. The method does not speciate the chemicals present. This is the final report on its development.
Negative Ion Sensors for Real-Time Downhole DNAPLs Detection
Strategic Environmental Research and Development Program (SERDP), Project CU-1089, 2003
This one-page research brief describes the development and testing of a probe that contains a heated membrane interface and a sensitive, fast-responding downhole detector. All performance objectives were met, including sensor responsiveness to all common organochlorine compounds. The haloprobe functions by converting halogenated molecules into water, carbon dioxide, and halogen ions. The halogen ions are counted and used to estimate the original molecule's concentration. The method does not speciate the chemicals present.
Technology Demonstration of Sensor Applications to Direct Push Platforms and Monitoring and Operations: Technical Report for Field Test 6
P. Jarski. and R. St. Germain.
NTIS: ADA424257, 82 pp, 2004
This report describes a demonstration of the haloprobe system, which consists of a Membrane Interface Probe (MIP™, Geoprobe Systems) coupled with a halogen-specific detector. Placing the detector downhole eliminates problems associated with returning the vapors to the surface (time lag, condensation, adsorption losses in transfer lines, and dilution of analytes in transfer lines).
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Last updated on Monday, November 10, 2008