Environmental impact of two successive chemical treatments in a small shallow eutrophied lake: Part I. Case of aluminium sulphate

This paper deals with the efficiency and effects of addition of aluminium sulphate on soft water quality of a shallow eutrophic lake. Almost all the controlled variables improved with treatment, especially nutrient concentrations such as soluble reactive phosphorus (SRP) and transparency. However, aluminium sulphate was not added in sufficient quantity to reduce the total phosphorus content. SRP concentration was significantly reduced in the short term. Moreover, external loading of phosphorus was high and not taken into account by the in-lake treatments. Finally, resuspension of sediment (polymictic lake) removed the alum hydroxide layer on the sediment surface, which reduced treatment effectiveness. No significant pH decrease was noted following alum addition. According to bibliographical toxicological data, monomeric aluminium content does not show any toxic effect on aquatic fauna and flora. In spite of low SRP in the water column, the treatment did not prevent appearance of Microcystis sp. colony (> 10 colony per ml) approximately 30 days after alum application.     

Miscanthus × Giganteus straw and pellets as sustainable fuels and raw material for activated carbon

Miscanthus × Giganteus is an excellent candidate for energy cultivation. Here we report, for the first time, the results of the pyrolysis of Miscanthus × Giganteus straw or pellets both in tubular reactor (3–6 g) and in rotary kiln (10–30 g). At 400–600°C the fractions obtained from both reactors are: solid 16–25 (wt.%); liquids 25–40; water 15–20 and gases 15–50. GC-MS analyses of pyrolysis liquids reveal the occurrence of phenolic derivatives and ethanol from lignin, furanic and linear oxygenated compounds from cellulose and hemicellulose. Finally the chars produced by the pyrolysis of M×G pellets in rotary kiln present good calorific values close to 29,000 J/g. Additionally, activated carbons with a BET surface area as high as 800–900 m²/g are produced from pellets. These results indicate that chars have a good potential either for energy production, e.g. briquetting, or as adsorbents precursors.     

Patterns of animal diversity in different forms of tree cover in agricultural landscapes.

As tropical regions are converted to agriculture, conservation of biodiversity will depend not only on the maintenance of protected forest areas, but also on the scope for conservation within the agricultural matrix in which they are embedded. Tree cover typically retained in agricultural landscapes in the neotropics may provide resources and habitats for animals, but little is known about the extent to which it contributes to conservation of animal species. Here, we explore the animal diversity associated with different forms of tree cover for birds, bats, butterflies, and dung beetles in a pastoral landscape in Nicaragua. We measured species richness and abundance of these four animal taxa in riparian and secondary forest, forest fallows, live fences, and pastures with high and low tree cover. We recorded over 20,000 individuals of 189 species including 14 endangered bird species. Mean abundance and species richness of birds and bats, but not dung beetles or butterflies, were significantly different among forms of tree cover. Species richness of bats and birds was positively correlated with tree species richness. While the greatest numbers of bird species were associated with riparian and secondary forest, forest fallows, and pastures with >15% tree cover, the greatest numbers of bat species were found in live fences and riparian forest. Species assemblages of all animal taxa were different among tree cover types, so that maintaining a diversity of forms of tree cover led to conservation of more animal species in the landscape as a whole. Overall, the findings indicate that retaining tree cover within agricultural landscapes can help conserve animal diversity, but that conservation efforts need to target forms of tree cover that conserve the taxa that are of interest locally. Preventing the degradation of remaining forest fragments is a priority, but encouraging farmers to maintain tree cover in pastures and along boundaries may also make an important contribution to animal conservation.     

Is the contribution of bacteria to terrestrial carbon budget greatly underestimated?

Some commonly found species of soil bacteria use low molecular weight organic acids as their sole source of carbon and energy. This study shows that acids such as citrate and oxalate (produced in large amounts by fungi and plants) can rapidly be consumed by these bacteria. Two strains, Ralstonia eutropha and Xanthobacter autotrophicus, were cultured on acetate- and citrate-rich media. The resulting CO₂ and/or HCO₃^- reacted with calcium ions to precipitate two polymorphs of calcium carbonate (CaCO₃), calcite and vaterite, depending on the quantity of slime produced by the strains. This production of primary calcium carbonate crystals by oxalate- and citrate-degrading bacteria from soil organic carbon sources highlights the existence of an important and underestimated potential carbon sink.     

Prenatal diagnosis of trisomy 10 p in a twin pregnancy

A twin pregnancy with trisomy 10 p due to a paternal 10;12 translocation is reported. The prenatal diagnosis steps followed in twin pregnancies are reviewed and the concordant features of trisomy 10 p seen in both fetuses confirm previous reports on the clinical features of this chromosomal defect.     

A pre/post evaluation of fatigue,stress and vigilance amongst commercially licensed truck drivers performing a prolonged driving task

Purpose. The main purpose of this research study was to evaluate changes in fatigue, stress and vigilance amongst commercially licensed truck drivers involved in a prolonged driving task. The secondary purpose was to determine whether a new ergonomic seat could help reduce both physical and cognitive fatigue during a prolonged driving task. Two different truck seats were evaluated: an industrial standard seat and a new truck seat prototype. Methods. Twenty male truck drivers were recruited to attend two testing sessions, on two separate days, with each session randomized for seat design. During each session, participants performed two 10-min simulated driving tasks. Between simulated sessions, participants drove a long-haul truck for 90 min. Fatigue and stress were quantified using a series of questionnaires whereas vigilance was measured using a standardized computer test. Results. Seat interactions had a significant effect on fatigue patterns. Conclusion. The new ergonomic seat design holds potential in improving road safety and vehicle accidents due to fatigue-related accidents.     

A quantum cascade laser infrared spectrometer for CO2 stable isotope analysis: Field implementation at a hydrocarbon contaminated site under bio-remediation

Real-time methods to monitor stable isotope ratios of CO_2 are needed to identify biogeochemical origins of CO_2 emissions from the soil–air interface. An isotope ratio infra-red spectrometer(IRIS) has been developed to measure CO_2 mixing ratio with δ~13C isotopic signature, in addition to mixing ratios of other greenhouse gases(CH_4, N2_O). The original aspects of the instrument as well as its precision and accuracy for the determination of the isotopic signature δ~13C of CO_2 are discussed. A first application to biodegradation of hydrocarbons is presented, tested on a hydrocarbon contaminated site under aerobic bio-treatment. CO_2 flux measurements using closed chamber method is combined with the determination of the isotopic signature δ~13C of the CO_2 emission to propose a non-intrusive method to monitor in situ biodegradation of hydrocarbons. In the contaminated area, high CO_2 emissions have been measured with an isotopic signature δ~13C suggesting that CO_2 comes from petroleum hydrocarbon biodegradation.This first field implementation shows that rapid and accurate measurement of isotopic signature of CO_2 emissions is particularly useful in assessing the contribution of contaminant degradation to the measured CO_2 efflux and is promising as a monitoring tool for aerobic bio-treatment.     

ESTIMATION OF THE HIEC1 LOSS PARAMETERS FOR ROUTING THE PROBABLE MAXIMUM FLOOD1

ABSTRACT: Twenty storm events were used to select design values of the HEC1 loss parameters STRTL and CNSTL in order to route the probable maximum flood, PMF, through the Englewood watershed, Ohio. The parameter STRTL represents the initial volume of water lost due to interception and incomplete saturation of the soil prior to the storm. The parameter CNSTL represents a continuous loss rate and depends only on the watershed. When optimized from each storm event, STRTL varied between 0.0 and 3.4 inches with an average of 1.0 inch; CNSTL varied between 0.02 and 0.26 inch/hour, and it followed a normal probability distribution with a mean of about 0.1 inch/hour. The absence of correlation between optimum CNSTL values and each of total rainfall, total loss, and runoff duration supported the selection of the mean CNSTL as a design value. PMF routing through the Englewood watershed revealed that the PMF at the outlet is not sensitive to STRTL, but highly affected by CNSTL variations. The insensitivity to STRTL was due to the presence of a dam at the outlet of the watershed that caused the buildup of water in the watershed, thereby masking the storage effect of STRTL. The peak PMF increased by about 27 percent when the design CNSTL was decreased to 0.05 inch! hour, and decreased by about 18 percent when the design CNSTL was increased to 0.15 inch/hour.