Determination of the dialdehyde glyoxal in workroom air-development of personal sampling methodology

The dialdehyde glyoxal (ethanedial) is an increasingly used industrial chemical with potential occupational health risks. This study describes the development of a personal sampling methodology for the determination of glyoxal in workroom air. Among the compounds evaluated as derivatizing agents; N-methyl-4-hydrazino-7-nitrobenzofurazan (MNBDH), 1,2-phenylenediamine (OPDA), 1-dimethylaminonaphthalene-5-sulfonylhydrazine (dansylhydrazine, DNSH) and 2,4-dinitrophenylhydrazine (DNPH), DNPH was the only reagent that was suitable. Several different samplers were evaluated for sampling efficiency of glyoxal in workroom air using DNPH as derivatizing agent; in-house DNPH coated silica particles packed in two different types of glass tubes, impingers containing acidified DNPH solution, filter cassettes containing glass fibre filters coated with DNPH, a commercially available solid phase cartridge sampler originally developed for formaldehyde sampling (Waters Sep-Pak DNPH-silica cartridge), and the commercially available SKC UMEx 100 passive sampler originally developed for formaldehyde sampling. Aldehyde atmospheres for sampler evaluation were generated with an in-house made vapour atmosphere generator coupled to a sampling unit, with the possibility of parallel sampling. The resulting glyoxal-DNPH derivative was determined using both LC-UV and LC-APCI-MS with negative ionization. By far, the highest recovery of glyoxal was obtained employing one of the in-house DNPH coated silica samplers (93%, RSD = 3.6%, n = 12).     

Changing roles of propagule, climate, and land use during extralimital colonization of a rose chafer beetle

Regardless of their ecosystem functions, some insects are threatened when facing environmental changes and disturbances, while others become extremely successful. It is crucial for successful conservation to differentiate factors supporting species’ current distributions from those triggering range dynamics. Here, we studied the sudden extralimital colonization of the rose chafer beetle, Oxythyrea funesta, in the Czech Republic. Specifically, we depicted the range expansion using accumulated historical records of first known occurrences and then explained the colonization events using five transformed indices depicting changes in local propagule pressure (LPP), climate, land use, elevation, and landscape structure. The slow occupancy increase of O. funesta before 1990 changed to a phase of rapid occupancy increase after 1990, driven not only by changes in the environment (climate and land use) but also by the spatial accumulation of LPP. Climate was also found to play a significant role but only during the niche-filling stage before 1990, while land use became important during the phase of rapid expansion after 1990. Inland waters (e.g., riparian corridors) also contributed substantially to the spread in the Czech Republic. Our method of using spatially transformed variables to explain the colonization events provides a novel way of detecting factors triggering range dynamics. The results highlight the importance of LPP in driving sudden occupancy increase of extralimital species and recommend the use of LPP as an important predictor for modeling range dynamics.     

Economics: Theory versus Practice in Wildlife Management

One of the most controversial issues in wildlife management in North America is the trend towards the commercialization of wildlife. The sale of hunting privileges and game ranching are forms of wildlife commercialization that have not been unanimously accepted, and widely opposing views exist on the merits and drawbacks of the use of economic incentives for the management of wild animals. In this essay the use of economics is explored from a theoretical "free market" perspective and from a more practical point of view. The issue of market failure is addressed and potential solutions are offered, such as tax incentives and government farm programs. Also the question of when market-oriented solutions are applicable to wildlife is discussed. We conclude that polarization of the issue is counterproductive and that some of the more innovative solutions to current wildlife management problems can be found between the opposite extremes of public ownership and the profit-motivated incentives offered by the market.     

Influences of aggregative behaviour on space occupation in the spider Zygiella x-notata (Clerck)

Summary The distribution of the spider Zygiella x-notata was examined using field populations of adult females occupying the outside frames of windows. The structure of the populations was aggregative, and the distribution of individuals on the window frames and the size of the webs were density dependent. Also, the sizes of the webs of neighbouring spiders on the same window alternated. This spatial organization involves interactions between neighbours. If one spider out of two is removed, and if all the webs are destroyed, remaining spiders that previously had small webs significantly increase the size of their construction. In contrast, individuals that previously had large webs do not modify the size of their construction. This shows that individuals of Z. x-notata respond to the presence of neighbours. The influence of intraspecific interactions in such a population is discussed.     

A note on environmental risk and the rate of discount: Comment

The sign of the adjustment to the riskless discount rate for environmental risk depends on whether the price of avoiding the consequences of the externality is seen as reducing expected net benefits or increasing expected costs. The conclusion is that the risk adjustment is positive when the externality is defined as reducing expected net benefits.     

The air speed of migrating birds and its relationship to the wind

Summary This paper deals with the flight speeds of migrating birds observed by radar over a Swiss Alpine pass. The distributions of air speeds for different classes of birds and the influence of the wind on air speeds were investigated. Our findings differ greatly from observations of bird migration over the North Atlantic Ocean and the North American continent. Our data reveal: (1) that the air speeds of the bulk of migrating birds were in the range of 8–18 m/s and that the amount of slow flyers (air speed below 5 m/s) was less than 5%; (2) that there was an obvious influence of the wind on air speeds and, moreover, the data showed a distinctly variable compensatory behavior among different bird classes; (3) that the wind component in the direction of the bird's heading was a better predictor for air speed than the wind direction. Although we do not speculate about possibilities and mechanisms of wind detection, a simple argument shows how birds could estimate wind directions if they do use the moving surface as a reference system.     

The use of composite sampling in contaminated sites—a case study

Simulated composite sampling was carried out using data from a contaminated site. The values obtained by composite sampling were compared with the results obtained using discrete (individual) samples. It is appropriate to use a modified investigation level (MIL) when using composite samples. The MIL is lower than the standard investigation level, (IL). Various MILs were considered in this study. Too low an MIL will indicate that some composite samples require further investigation, when none of the discrete samples comprising the composite would have exceeded the IL. Too high an MIL will result in some discrete samples that exceed the IL being missed. A suggested MIL is IL/ where n is the number of discrete samples in the composite sample. This MIL was found to give few false negatives but many fewer false positives than the IL/n rule. Although this MIL was effective on the test data it could be site specific. Some local areas of high concentration may be missed with composite samples if a lower investigation level is used. These however do not make a large contribution to the health risk because they will have a contaminant level only slightly higher than the IL, and the neighboring samples must have a low concentration of the contaminant. The increased risk due this cause may be more than offset by the higher sampling density made possible through the economies of composite sampling When composite sampling is used as the first phase of an adaptive cluster-sampling scheme, it must be augmented by additional samples to delineate the contaminated area to be cleaned up. Composite sampling can also be effectively used in a clean up unit technique, where a clean up unit is represented by one or more composite samples. Suggestions are given for when composite sampling can be used effectively.     

Cystic fibrosis prenatal diagnosis: Confirmation of an equivocal microvillar enzyme result by direct analysis of the common gene mutation

A child was tentatively diagnosed as having cystic fibrosis, based on neonatal presentation with severe gastrointestinal complications; the diagnosis was not confirmed biochemically and no tissues were available for DNA analysis. The mother presented in her subsequent pregnancy, and microvillar enzyme analysis of cell-free amniotic fluid at both 18 and 20 weeks gestation gave equivocal results. The pregnancy was terminated voluntarily because of a trend towards abnormal enzyme assay results on the second amniocentesis. Retrospectively, fetal tissues were found to be homozygous for the most common mutation of the cystic fibrosis gene (AF₅₀₈), which confirmed the prenatal assessment and suggested that the first infant of the couple was probably also affected by the disease.