DNAPL Flow Behavior in a Contaminated Aquifer: Evaluation of Field Data

A pool of dense nonaqueous phase liquid (DNAPI.) containing TCE and other chlorinated solvents has been removed from the subsurface at Hill Air Force Base, Uthah. as part of an interim remedial action. The removal of the DNAPI. pool means that future off-site migration of dissolved contaminants in the ground water is minimized, and costs for final remedial actions are reduced. A pump-and-treat system recovered more than 23.000) gallons of DNAPI. and one million gallons of contaminated ground water from the aquifer. The efficiency of this remedial action was evaluated on the basis of extensive field and laboratory data. The behavior of DNAPI. flow in the aquifer sands was characterized by collecting core samples from two borings in the DNAPL pool and measuring relative permeabilities and DMAPI. saturation. Core Hooding results show that approximately one-third of the DNAPI. originally in the pool is not recovered by water displacement, but remains as a residual saturation held in place by capillary pressure. However, subsequent Hooding with two pore volumes of surfactant solution reduced the residual DNAPI. saturation in the sand by one order of magnitude. Analytical and numerical models for the DNAPI flow behavior at the site were developed. This is the first time that such models have been developed and applied to an actual DNAPI. pumping lest conducted in the field. Because measured permeabilities and residual saturations were used lo calibrate the models. the model predictions could be used lo provide valuable insights into the controlling mechanisms for DNAPL recovery. The data collection and modeling procedures outlined in this paper can be used lo enhance the efficiency and minimize the cost 10 clean up this and other DNAPI.-contaminated sites.     

Identification of cytochrome P450 1B-like sequences in two teleost fish species (scup, Stenotomus chrysops and plaice, Pleuronectes platessa) and in a cetacean (striped dolphin, Stenella coeruleoalba).

The cytochromes P450 (CYP) constitute a multigene family of enzymes playing a critical role in the oxidation of many endogenous and xenobiotic substrates. The CYP1 family is of particular interest in environmental toxicology because its members are dominant in the metabolism of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and aryl amines. Three members of the CYP1 family, CYP1A1, CYP1A2, and CYP1B1, have been identified in mammals. We report here on the identification and cloning of cytochrome P4501B-like sequences from two teleost fish species and a marine mammal. Sequences clustering with CYP1B1 in phylogenetic analysis were obtained from liver cDNA of scup (Stenotomus chrysops), genomic DNA of plaice (Pleuronectes platessa), and liver cDNA of striped dolphin (Stenella coeruleoalba).     

Perturbation of an electrostatic probe by a spacecraft at small speed ratios

The disturbance of an electrostatic probe, by the spacecraft carrying it, in the intermediate altitude regime from about 3000 km to the plasmapause, is discussed. Three kinds of disturbance are studied: loss of symmetry of the probe sheath due to the presence of the spacecraft; creation of potential barriers around the probe; and particle removal, or shadowing, by the spacecraft. The first of these effects is shown to be nonexistent for a spherical probe if it is operated under orbit-limited conditions. Methods are given for estimating the magnitudes of the other two effects in any given situation. The electrostatic probe experiment on the Explorer 31 spacecraft is discussed as an example.     

Sm–Nd dating of fluorite from the worldclass Montroc fluorite deposit, southern Massif Central, France

A three-point Sm–Nd isotope isochron on fluorite from the very large Montroc fluorite vein deposit (southern Massif Central, France) defines an age of 111±13 Ma. Initial _Nd of –8.6 and initial ⁸⁷Sr/⁸⁶Sr of ~0.71245 suggest an upper crustal source of the hydrothermal system, in agreement with earlier work on fluid inclusions which indicated a basinal brine origin. The mid-Cretaceous age of ~111 Ma suggests the Albian/Aptian transition as the most likely period for large-scale fluid circulation during a regional extensional tectonic event, related to the opening of the North Atlantic ocean.Editorial handling: B. Lehmann     

Le phytoplancton du lac de Neuchâtel

Résumé L'analyse du phytoplancton récolté de 1959 à 1962 montre qu'à son tour le lac de Neuchatel a atteint un degré de pollution favorisant l'implantation et l'expansion d'espèces indésirables. Le r?le que jouent actuellementAphanizomenon flos-aquae, Oscillatoria rubescens, O. prolifica, Tabellaria fenestrata, entre autres, ainsi que lesChlorophycées, a rapidement modifié la physionomie de la biocénose. L'inventaire des algues planctoniques dressé parFuhrmann en 1897/1898 fournit d'autre part un élément de comparaison mettant en évidence l'évolution survenue dans ce bassin subjurassien au cours de 65 années. Travail réalisé avec l'appui du Fonds national suisse de la Recherche.     

FFT-enhanced IHS transform method for fusing high-resolution satellite images

Existing image fusion techniques such as the intensity–hue–saturation (IHS) transform and principal components analysis (PCA) methods may not be optimal for fusing the new generation commercial high-resolution satellite images such as Ikonos and QuickBird. One problem is color distortion in the fused image, which causes visual changes as well as spectral differences between the original and fused images. In this paper, a fast Fourier transform (FFT)-enhanced IHS method is developed for fusing new generation high-resolution satellite images. This method combines a standard IHS transform with FFT filtering of both the panchromatic image and the intensity component of the original multispectral image. Ikonos and QuickBird data are used to assess the FFT-enhanced IHS transform method. Experimental results indicate that the FFT-enhanced IHS transform method may improve upon the standard IHS transform and the PCA methods in preserving spectral and spatial information.