Contamination of Chalk groundwater by chlorinated solvents : a case study of deep penetration by non-aqueous phase liquids

The transport behaviour of chlorinated solvents, both in the aqueous phase and as a dense non-aqueous phase liquid (DNAPL), in fissured microporous aquifers is reviewed. The presence of DNAPL in aquifers is especially serious as it is likely to be the main subsurface source of contamination and, given the slow rates of dissolution in groundwater, may persist for decades. However, the identification and quantification of DNAPLs in fractured aquifers present many practical problems and are often not achievable. A case study of a Chalk site which had been contaminated by chlorinated solvents demonstrated that the use of a range of techniques, including depth profiling of solvent porewater concentrations in cored boreholes, can provide clear evidence for the presence of DNAPL at depth, although DNAPL was not itself observed. Theoretical considerations and field observations confirmed that DNAPL movement is via fractures rather than through the microporous matrix

Executive Summary of the Workshop on Polarization and Beam Energy Measurements at the ILC

This note summarizes the results of the 'Workshop on Polarization and Beam Energy Measurements at the ILC', held at DESY (Zeuthen) April 9-11 2008. The topics for the workshop included (1) physics requirements, (2) polarized sources and low energy polarimetry, (3) BDS polarimeters, (4) BDS energy spectrometers, and (5) physics-based measurements of beam polarization and beam energy from collider data. Discussions focused on the current ILC baseline program as described in the Reference Design Report (RDR), which includes physics runs at beam energies between 100 and 250 GeV, as well as calibration runs on the Z-pole. Electron polarization of P{sub e{sup -}} {approx}> 80% and positron polarization of P{sub e{sup +}} {approx}> 30% are part of the baseline configuration of the machine. Energy and polarization measurements for ILC options beyond the baseline, including Z-pole running and the 1 TeV energy upgrade, were also discussed

THE EFFECT OF METHIONINE AND METHIONINE PRECURSORS ON THE GROWTH OF STREPTOCOCCUS LACTIS

During the course of a study on the amino acid requirements of a strain of Streptococcus lacti8, it was observed that the organism manifested adequate growth in the absence of added methi-onine. Further investigations with a number of strains of S. lactis revealed that all were able to manifest appreciable growth in the absence of added methionine. A detailed study using one of these strains showed that it responded favorably to the addition of amino acids previously shown to be precursors of methionine in the rat. It appeared that the organism readily synthesized methionine and that the pathway of the synthesis was strikingly similar to that established for the rat. EXPERIMENTAL METHODS The strain of S. lactis used in this study was from the departmental culture collection and was selected on the basis of its excellent growth in a synthetic medium. Throughout the experimental work the culture was carried in litmus milk and routinely transferred every seven days. The synthetic medium used was that of Henderson and Snell (1948). The modifications of this medium by Anderson and Elliker (1953) were not adopted in toto, the exception being the ascorbic level which was lowered to 20 mg per 100 ml of medium. The original medium was further modified to the extent that the citrate level of the medium was reduced to 10 mg per ml and acetate was deleted (Kizer and Speck, 1954). Each medium tested was inoculated initially from a 24 hr litmus milk culture using 0.05 per cent inoculum and incubation at 32 C for 24 hr. This was followed by two serial 24 hr subcultures in the same medium using 0.05 per cent of the previous 24 hr culture for inoculum. Cultures were tested in 2 ml of medium, and inoculatio