Plumes Focus Area

PFA Plumes Focus Area. National Technology Needs Assessment. Review Draft, U.S. Department of Energy, May 17, 1996. 

Successfiil inq>lemeiitation of such an approach would considerably reduce both the time and cost of in situ biotreatment. Pretceating groundwaters with sonication techniques would form VOCs that could be removed effectively by either bioremediation technologies or a dual vapor extraction technique (developed by Stanford University under the VOC-Arid Program, now part of Plumes Focus Area). Sonication could also be coupled widi technologies aimed at mobilizing dense nonaqueous phase liquids (DNAPLs) in the subsur ce, such as surfactant floodii. ... 

In consultation widi DOE and the Plumes Focus Area, representative target VOCs and SVOCs were determined. Potential VOCs and SVOCs present at various DOE facilities include TCE, trichloroediane (TCA), 1,2-ethylene dibromide (EDB), CCU, CHCI3, vinyl chloride (VC), 1,1- chloroethylene (DCE), 1,1,2,2-tetrachloroetfaylene (PCE), and polychlorinated b henyls (PCBs). After determination of the target compounds, the subsequent tasks focused on the integrated in-well sonication/in-well vapor str ing, and biodegradation system. 

Containment Plumes-Containment and Remediation-Focus Area, DOE/EM-0248, National Technical Information Services, Springfield, VA. 

Plumes and Landfills Stabilization Focus Areas. Progress Report, U. S. Department of Energy, Winter, 1996. 

The method or methods employed to remediate an aquifer vary, depending on the type, degree, and extent of contamination. Where pollution is shallow and dispersed over a small area, the sediments can sometimes be dug up and transported to a landfill designed especially to isolate the contaminants. Permeable reaction barriers can be installed to intercept a contaminant plume and strip pollutants from it, if the plume is shallow and narrowly focused. 

In particular, the study of plumes of molecules released in water from a submerged source has been the focus of substantial research. The migration of the molecules from within or from the surface of a submerged, buried munition is similar to the case of munitions buried in the ground. Following that release there is little similarity. Almost no work has been done to date to examine the processes that affect the molecules released from an object buried in the seabed. This may form a fruitful area for research. 

The sample aerosol is transferred to the plasma where it is desolvated, vaporised, atomised and excited and/or ionised by the plasma. The atoms and ions emit their characteristic rays which are dispersed as monochromatic rays using a monochromator. To do this, the radiation emitted from the area selected at a given height of the plasma plume is focused on the monochromator s inlet slit. 

When a powerful la.ser pulse is focused on a 5- to 30-pm spot on a sample surface, a small amount of the solid is vaporized regardless of whether it is a conductor. The resulting plume is made up of atoms, ions, and molecules. In the microprobe, the contents of the plume arc excited by a spark between a pair of small electrodes located immediately above the surface of the sample. The re.sulting radiation is then focused on a suitable monochromator-detection system. With this type of source, it has been possible to determine the trace element composition of single blood cells and tiny inclusion areas in alloys. The laser can be scanned across a surface to obtain a spatially resolved representation of surface composition. 

Principles and Characteristics Laser ablation is conceptually very simple, but mechanistically complicated. The process involves coupling of the photon energy of a laser pulse (typically about 20-30 ns wide, with an energy of 1-10 Jcm ) into the surface of a solid, resulting in evaporation and ejection of various species from the surface (the so-called plume ) within 10 to 10 s. The first experiments were carried out in 1962 [32]. When focused to a small area, a laser beam provides enormous power densities and electromagnetic fields. The plume , presumably a plasma, is accompanied by shock waves and electrical breakdown. The ejected material may eventually be deposited as a thin film. It is possible, by suitable selection of laser power and focus, to ablate a range of plastic materials in a controlled manner. For some matrices the polymer melts and diffuses away from the centre of the ablation site, leading to the forma-... 

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