Assessment of the efficacy of slow-release formulations of the tribenuron-methyl herbicide in field-grown spring wheat

Environmental Science and Pollution Research - The efficacy of slow-release formulations of tribenuron-methyl (TBM) embedded in the matrix of degradable poly(3-hydroxybutyrate) blended with birch...     

Festering food: chytridiomycete pathogen reduces quality of Daphnia host as a food resource

When parasitic infections are severe or highly prevalent among prey, a significant component of the predator's diet may consist of parasitized hosts. However, despite the ubiquity of parasites in most food webs, comparisons of the nutritional quality of prey as a function of infection status are largely absent. We measured the nutritional consequences of chytridiomycete infections in Daphnia, which achieve high prevalence in lake ecosystems (>80%), and tested the hypothesis that Daphnia pulicaria infected with Polycaryum laeve are diminished in food quality relative to uninfected hosts. Compared with uninfected adults, infected individuals were smaller, contained less nitrogen and phosphorus, and were lower in several important fatty acids. Infected zooplankton had significantly shorter carapace lengths (8%) and lower mass (8-20%) than uninfected individuals. Parasitized animals contained significantly less phosphorus (16-18% less by dry mass) and nitrogen (4-6% less) than did healthy individuals. Infected individuals also contained 26-34% less saturated fatty acid and 31-42% less docosahexaenoic acid, an essential fatty acid that is typically low in cladocera, but critical to fish growth. Our results suggest that naturally occurring levels of chytrid infections in D. pulicaria populations reduce the quality of food available to secondary consumers, including planktivorous fishes, with potentially important effects for lake food webs.     

Spatial variability of infaunal nematode and polychaete assemblages in two muddy subtidal habitats

Spatial variation of populations and their assemblages is an important component of many aspects of ecology, including the maintenance of species diversity. In nature, organisms are generally aggregated in patches or form gradients or other spatially related patterns. This investigation quantified the degree of spatial structure in benthic invertebrate assemblages. It examined the distribution of infaunal assemblages of different size, mobility and contrasting life-history strategies (i.e. meiofaunal nematodes and macrofaunal polychaetes) in two offshore muddy habitats in the Celtic Deep and the NW Irish Sea off the west coast of the United Kingdom. The more heterogeneous habitat in the NW Irish Sea was characterised by higher tidal stress and bottom temperature while greater water depth, mean particle diameter and organic carbon content was typical for the comparatively homogeneous environment in the Celtic Deep. In both habitats, the environmental conditions became increasingly dissimilar with separation. A total of 125 nematode and 88 polychaete species were recorded with 69% of the nematode and 49% of polychaete species present at both study sites. Occurrence frequency of species, species diversity and average similarity of assemblage composition was higher in the Celtic Deep than in the NW Irish Sea. Results from correlation analyses revealed statistically robust relationships of community similarity and sample distance. Given their small size and low mobility, nematodes were more susceptible to within-habitat physical variability than larger-sized, more mobile polychaetes. This, coupled with limits to long-distance dispersal and likely restrictions in gene flow, resulted in a significant decrease in community similarity with distance at the spatial scales sampled (i.e. within 0.1–23 km). Polychaetes, in contrast, combined a higher dispersal potential (>23 km) with a relatively high tolerance to within-habitat environmental variability and these were the most likely causes for non-significant relationships between the similarity of their assemblages and sample distance. The potential mechanisms causing the observed variation and implications of results for environmental management strategies are discussed. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Pyrolysis of plastic packaging waste: A comparison of plastic residuals from material recovery facilities with simulated plastic waste

Pyrolysis may be an alternative for the reclamation of rejected streams of waste from sorting plants where packing and packaging plastic waste is separated and classified. These rejected streams consist of many different materials (e.g., polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polyethylene terephthalate (PET), acrylonitrile butadiene styrene (ABS), aluminum, tetra-brik, and film) for which an attempt at complete separation is not technically possible or economically viable, and they are typically sent to landfills or incinerators. For this study, a simulated plastic mixture and a real waste sample from a sorting plant were pyrolyzed using a non-stirred semi-batch reactor. Red mud, a byproduct of the aluminum industry, was used as a catalyst. Despite the fact that the samples had a similar volume of material, there were noteworthy differences in the pyrolysis yields. The real waste sample resulted, after pyrolysis, in higher gas and solid yields and consequently produced less liquid. There were also significant differences noted in the compositions of the compared pyrolysis products.     

Evaluation of limits for effective flame acceleration in hydrogen mixtures

Results of experiments and data analysis on turbulent flame propagation in obstructed channels are presented. The data cover a wide range of mixtures: H₂/air, H₂/air/steam (from lean to rich) at normal and elevated initial temperatures (from 298 to 650 K) and pressures (from 1 to 3 bar); and stoichiometric H₂/O₂ mixtures diluted with N₂, Ar, He and CO₂ at normal initial conditions. The dataset chosen also covers a wide range of scales exceeding two orders of magnitude. It is shown that basic flame parameters, such as mixture expansion ratio σ, Zeldovich number β and Lewis number Le, can be used to estimate a priori a potential for effective flame acceleration for a given mixture. Critical conditions for effective flame acceleration are suggested in the form of correlations of critical expansion ratio σ^* versus dimensionless effective activation energy. On this basis, limits for effective flame acceleration for hydrogen combustibles can be estimated. Uncertainties in determination of critical σ^* values are discussed.     

Safety climate factors, group differences and safety behaviour in road construction

This study determines the factor structure of safety climate within a road construction organization using a modified version of the safety climate questionnaire (SCQ). It also investigates the relationship between safety climate and safety performance. The SCQ was administered to 192 employees from two districts and in two job categories — construction and maintenance. A behavioural observation measure of safety performance was also developed. Factor analysis derived six factors, which were similar to those obtained in an earlier study using the SCQ. Differences in the safety climate of job sub-groups were found on two of the factors. No differences between the two districts were found. No relationship was found between safety climate and the safety performance measure. While identical safety climate factors cannot apply to all organizations, some general safety climate factors may emerge. Discussion focuses upon the measurement of safety climate.     

Formation of singlet oxygen during farmorubicin oxidation.

The enhanced generation of singlet oxygen (1O2) during oxidation of farmorubicin in the Co(II) + H2O2 system was studied using chemiluminescent, fluorescent and spectrophotometic techniques. The influence of 1O2-quenchers, catalase, superoxide anion radical (O2*-) and hydroxyl radical (HO*) scavengers on the light emission was studied. The spectrophotometric determination of 1O2 was based on bleaching of p-nitrosodimethylaniline caused by an intermediate product of the reaction of 1O2 with imidazole, and was followed by monitoring the decrease in optical density at 440 nm.