Snowblower injuries in Vermont, 1981–1984

The Vermont Department of Health carried out two studies of snowblower injuries in Vermont during the winters of 1982–1983 and 1983–1984. The first was a case-control study in which we assessed risk factors that predisposed operators to injury during snowblower use. We found 20 persons who had been injured by snowblowers and matched 28 controls to these by neighborhood. In this study, owning a snowblower for 1 year or less and having operated a snowblower for 10 days or less in one's lifetime were significantly associated with injury. The second study was population-based. We estimated that approximately 1.5% of Vermont residents owned snowblowers during the winter of 1982–1983 and that, among snowblower owners, injuries occurred at a rate of 1.3/1,000 person-years of ownership (0.1% chance of injury).     

The future for coal in Western Europe

The past twenty years have demonstrated a striking flexibility in fuel supplies. Does this mean, now the dangers of import dependence have been demonstrated, that it will in the future be equally easy to move to a different composition of energy supplies with a larger role for indigenous coal? An examination of the factors determining interfuel substitution over the past twenty years suggests that present circumstances do not appear entirely favourable to coal revival.     

AN INTEGRATIVE APPROACH TOWARDS UNDERSTANDING ECOLOGICAL RESPONSES TO DAM REMOVAL: THE MANATAWNY CREEK STUDY1

ABSTRACT: Dam removal has been proposed as an effective method of river restoration, but few integrative studies have examined ecological responses to the removal of dams. In 1999, we initiated an interdisciplinary study to determine ecological responses to the removal of a 2 m high dam on lower Manatawny Creek in southeastern Pennsylvania. We used an integrative monitoring program to assess the physical, chemical, and biological responses to dam removal. Following removal in 2000, increased sediment transport has led to major changes in channel form in the former impoundment and downstream reaches. Water quality did not change markedly following removal, probably because of the impoundment's short hydraulic residence time (less than two hours at base flow) and infrequent temperature stratification. When the impoundment was converted to a free flowing reach, the composition of the benthic macroinvertebrate and fish assemblages in this portion of Manatawny Creek shifted dramatically from lentic to lotic taxa. Some fish species inhabiting the free flowing reach downstream from the dam were negatively affected by large scale sediment transport and habitat alteration following dam removal, but this appears to be a short term response. Based on our observations and experiences in this study, we provide a list of issues to evaluate when considering future dam removals.     

Decreased pH does not alter metamorphosis but compromises juvenile calcification of the tube worm Hydroides elegans

Using CO₂ perturbation experiments, we examined the pre- and post-settlement growth responses of a dominant biofouling tubeworm (Hydroides elegans) to a range of pH. In three different experiments, embryos were reared to, or past, metamorphosis in seawater equilibrated to CO₂ values of about 480 (control), 980, 1,480, and 2,300 μatm resulting in pH values of around 8.1 (control), 7.9, 7.7, and 7.5, respectively. These three decreased pH conditions did not affect either embryo or larval development, but both larval calcification at the time of metamorphosis and early juvenile growth were adversely affected. During the 24-h settlement assay experiment, half of the metamorphosed larvae were unable to calcify tubes at pH 7.9 while almost no tubes were calcified at pH 7.7. Decreased ability to calcify at decreased pH may indicate that these calcifying tubeworms may be one of the highly threatened species in the future ocean.     

Trace-level measurement of complex combustion effluents and residues using multidimensional gas chromatography-mass spectrometry (MDGC-MS)

The identification and quantitation of non-method-specific target analytes have greater importance with respect to EPA's current combustion strategy. The risk associated with combustion process emissions must now be characterized. EPA has recently released draft guidance on procedures for the collection of emissions data to support and augment site-specific risk assessments (SSRAs) as part of the hazardous waste incineration permitting process. This guidance includes methodology for quantifying total organic (TO) emissions as a function of compound volatility. The ultimate intent is to compare the amount of organic material identified and quantified by target analyte-specific methodologies to organic emissions quantified by the TO methodology. The greater the amount accounted for by the target analyte-specific methodologies, the less uncertainty may be associated with the SSRAs. A limitation of this approach is that the target analyte-specific methodologies do not routinely quantify compounds of low toxicological interest; nor do they target products of incomplete combustion (PICs). Thus, the analysis can miss both toxic and non-toxic compounds. As a result, it is unknown whether the uncharacterized fraction of the TO emission possesses toxic properties. The hypothesis that we propose to test is that organic emissions and organics extracted from particulate matter (PM) are more complex than standard GC-MS-based instrumentation can currently measure. This complexity can affect quantitation for toxic compounds, thereby potentially affecting risk assessments. There is a pressing need to better characterize these organic emissions from hazardous waste incinerators and PM extracts from various other combustion sources. We will demonstrate that multidimensional gas chromatography-mass spectrometry (MDGC-MS) procedures significantly improve chromatographic separation for complex environmental samples. Sequential repetitive heart-cutting MDGC, with coupled mass spectrometry will be shown to be a complete analysis technique. The ability of this technique to disengage components from complex mixtures taken from hazardous and municipal waste incinerators will be shown.     

Resuspension of sediment-associated Escherichia coli in a natural stream

In this study, a tracer bacteria was used to investigate the resuspension and persistence of sediment-associated bacteria in a small alluvial stream. The study was conducted in Swan Creek, located within the Grand River watershed of Ontario, Canada. A 1.1-m2 section of the bed was seeded with a strain of Escherichia coli resistant to nalidixic acid (E. coli NAR). The survival, transport, and redistribution of the tracer bacteria within a 1.7-km river section downstream of the source cell was assessed for a 2-mo period following the introduction of the tracer bacteria. This study has illustrated that enteric bacteria can survive in bed sediments for up 6 wk and that inactivation of the tracer bacteria resembled typical first-order decay. Critical conditions for resuspension, as well as resuspension rates, of sediment-associated bacteria were determined for several storm events. The critical shear stress for E. coli NAR resuspension in Swan Creek ranged from 1.5 to 1.7 N m(-2), which is comparable with literature values for critical shear stresses for erosion of cohesive sediments. Bacteria resuspension was primarily limited to the rising limb of storm hydrographs implying that a finite supply of sediment-associated bacteria are available for resuspension during individual storm events. The information presented in this paper will further the development of representative microbial water quality models.     

Estimating behavioral parameters in animal movement models using a state-augmented particle filter

Data on fine-scale animal movement are being collected worldwide, with the number of species being tagged and the resolution of data rapidly increasing. In this study, a general methodology is proposed to understand the patterns in these high-resolution movement time series that relate to marine animal behavior. The approach is illustrated with dive data from a northern fur seal (Callorhinus ursinus) tagged on the Pribilof Islands, Alaska, USA. We apply a state-space model composed of a movement model and corresponding high-resolution vertical movement data. The central goal is to estimate parameters of this movement model, particularly their variation on appropriate time scales, thereby providing a direct link to behavior. A particle filter with state augmentation is used to jointly estimate the movement parameters and the state. A multiple iterated filter using overlapping data segments is implemented to match the parameter time scale with the behavioral inference. The time variation in the auto-covariance function facilitates identification of a movement model, allows separation of observation and process noise, and provides for validation of results. The analysis yields fitted parameters that show distinct time-evolving changes in fur seal behavior over time, matching well what is observed in the original data set.     

Antibiotic resistome mostly relates to bacterial taxonomy along a suburban transmission chain

• The α-diversities of resistome were lower in manure and compost than in soils. • There were significant correlations between the resistome and bacterial taxonomy. • Bacterial taxonomy was the highest in explaining resistome variances. Antibiotic resistance genes comprising antibiotic resistome are of great concern due to their increase in the environment. Recent evidence of shared resistomes between soils and animal husbandry has imposed potential risks to human health. However, the correlation between a given community’s resistome and bacterial taxonomic composition is controversial. Here, a transmission chain of resistomes from swine manure to compost and compost-amended soil were analyzed in five suburban areas of Beijing, China, with unamended agricultural soils as control soils. Antibiotic resistomes and bacterial taxonomic compositions were distinct between (I) manure and compost; and (II) compost-amended and control soils. In manure, compost, and compost-amended soils, the β-diversity of the resistome and bacterial taxonomic composition was significantly correlated, while no correlation was detected in control soils. Bacterial taxonomic composition explained 36.0% of total variations of the resistome composition, much higher than environmental factors. Together, those results demonstrated that antibiotic resistome was closely related to bacterial taxonomic composition along the suburban transmission chain.