Spatial distribution of jet fuel in the vadoze zone of a heterogeneous and fractured soil.

The goal of the present work is to screen and evaluate all available data before selecting and testing remediation technologies on heterogeneous soils polluted by jet fuel. The migration pathways of non-aqueous phase liquids (NAPLs) in the subsurface relate closely with soil properties. A case study is performed on the vadoze zone of a military airport of north-west Poland contaminated by jet fuel. Soil samples are collected from various depths of two cells, and on-site and off-site chemical analyses of hydrocarbons are conducted by using Pollut Eval apparatus and GC-MS, respectively. The geological conceptual model of the site along with microscopic and hydraulic properties of the porous matrix and fractures enable us to interpret the non-uniform spatial distribution of jet fuel constituents. The total concentration of the jet fuel and its main hydrocarbon families (n-paraffins, major aromatics) over the two cells is governed by the slow preferential flow of NAPL through the porous matrix, the rapid NAPL convective flow through vertical desiccation and sub-horizontal glaciotectonic fractures, and n-paraffin biodegradation in upper layers where the rates of oxygen transfer is not limited by complexities of the pore structure. The information collected is valuable for the selection, implementation and evaluation of two in situ remediation methods.

Routine analysis of alcohol and nonylphenol polyethoxylates in wastewater and sludge using liquid chromatography-electrospray mass spectrometry.

A wide range of alcohol and nonylphenol polyethoxylates was determined by separation on a reversed-phase liquid chromatographic column, followed by electrospray ionisation-mass spectral analysis. The compounds were separated chromatographically according to their aliphatic chain length. The mass spectral analysis functioned as a second separation step during which homologues of the ethoxylates were separated according to their polyethoxylate chain length. In this manner a truly orthogonal separation was obtained. The compounds were detected as ammonium complexes. The analysis presented is capable of qualitative and quantitative determination of a large number of ethoxylates as well as their metabolites in a single run. The method was applied to many different sample types, ranging from primary and treated wastewater to sludge. Batches of 50 real samples were routinely analysed without the need for cleaning the mass spectrometer or regeneration of the column. By utilising the extracted mass chromatograms, detection limits of 1 to 10 microg/l could be obtained for individual compounds in water samples, while the detection limits were around 100 microg/kg in sludge, depending on the degree of pollution.

What makes a vibble a vibble? A developmental study of category generalization.

Young children appear to know when a novel label for a novel object is a common noun. The present study was concerned with the properties of a named object that children assume to be true of other members of the category that is specified by such a noun. Preschoolers, second graders, and college students were shown drawings of objects and given nonsense labels for those objects. They then viewed other objects that varied from the labeled ones along 4 particular attributes and were asked to decide if those other objects should also receive the same label. Preschoolers focused mostly on single attributes in making category decisions, and their choices of attributes were evenly distributed among the 4 types. Older individuals primarily exhibited multiple attribute rules. The results are discussed in terms of developmental differences in the modes of processing that are used and in the types of knowledge that are brought to bear on the word learning situation.

Dropping in and dropping out: participation motives of current and former youth gymnasts.

This study examined motives for participating in and discontinuing sport for 106 competitive, recreational, and former youth gymnasts. Similar to previous studies on participation motives in children's sport, gymnasts cited multiple reasons for their attraction to sport with the most important being competence, fitness, and challenge for the competitive gymnasts; competence, fitness, fun and situational for the recreational gymnasts; and competence, action, challenge and fun for the former gymnasts. A factor analysis was conducted and revealed seven categories of motivational factors, similar to those found by Gill et al. (1983). No support was found for a relationship between motives for gymnastic participation and reasons for attrition. The most important reasons for leaving gymnastics were having other things to do, injuries, not liking the pressure, not having enough fun, and too time consuming.