Regulation of respiration during juvenile development of Sepia officinalis (Mollusca: Cephalopoda)

A culture of juvenile Sepia officinalis L. was kept during summer 1985 in the aquaria of the Station Marine, Wimereux, France. During the first four months of juvenile development, oxygen consumption under increasing hypoxia was measured with a closed respirometer. The experiments revealed a high regulatory capacity of juvenile S. officinalis. The critical oxygen concentrations were calculated and their ontogenetical evolution was studied. The critical oxygen concentration increased with increasing development. A linear relationship emerged between the critical oxygen concentration and the logarithm of the wet weight [CO_c (mg O₂ l^-1)=-0.393+0.893×log₁₀(W _w )]. The decreasing regulatory capacity of growing S. officinalis is most probably related to adaptations to a changing ecological environment during development. Another possibility is a physiological change, most probably related to the shift from embryonic to adult hemocyanin.     

Quantification of the effect of fumigation on short- and long-term nitrogen mineralization and nitrification in different soils

The effect of soil fumigation on N mineralization and nitrification needs to be better quantified to optimize N fertilizer advice and predict NO(-)(3) concentrations in crops and NO(-)(3) leaching risks. Seven soils representing a range in soil texture and organic matter contents were fumigated with Cyanamid DD 95 (a mixture of 1,3-dichloropropane and 1,3-dichloropropene). After removal of the fumigant, the fumigated soils and unfumigated controls were incubated for 20 wk and N mineralization and nitrification were monitored by destructive sampling. The average short-term N mineralization rates (k(s)) were significantly larger in the fumigated than in the unfumigated soils (P = 0.025), but the differences in k(s) between fumigated and unfumigated soils could not be related to soil properties. The average long-term N mineralization rates (k(l)) were slightly larger in the fumigated soils but the difference with the unfumigated soils was not significant. Again, the differences in k(l) values could not be related to soil properties. Nitrification was inhibited completely for at least 3 wk in all soils, and an effect on nitrification could be observed up to 17 wk in one soil. An S-shaped function was fitted to the nitrification data corrected for N mineralization, and both the rate constant (gamma) and the time at which maximum nitrification was reached (t(max)) were strongly correlated to soil pH. However, since no correlations were found between the effect of fumigation on N mineralization and soil properties, taking into account the effects of fumigation in fertilizer advice and in the prediction of NO(-)(3) leaching risks will need further research.     

Techniques to Reduce the Impact of Asulam Drift from Helicopter Sprayers on Native Vegetation

Asulam is often applied from the air to control bracken. This herbicide affects other ferns and spray drift could affect their survival. This paper discusses the use of bioassays to assess drift (a) spatially around a single bracken patch, (b) downwind from sprayed areas, and (c) spatially in undulating terrain and with different vegetation cover types. The aims were to develop policies to protect sensitive habitats. It is suggested that “no-spray” buffer zones in excess of 160–180 m are needed to minimise risk. Protection of rare ferns from overstorey vegetation or from steep slopes did not occur. Although less drift was found upwind there was significant damage at the end of the helicopter runs because of errors in switching the sprayer on and off.     

Curriculum Development in Environmental Science: A Case Study on Paradigm and Institutions

/ The case of "Environment and Development" at Leiden University, the Netherlands, offers an example of developing a new environmental science curriculum in a conservative, disciplines-oriented university context. The core of this history is the long-term struggle of environmental science to evolve from the level of doing applied interdisciplinary studies and establish itself as a distinct body of knowledge with its own theory level, i.e., a discipline of its own. The struggle itself as well as its final outcome, a "bidisciplinary" curriculum in which both environmental science and one social science are expressed as disciplines (hence not environmental science as a mere "field of application") may be of value in other "classical" universities, too. KEY WORDS: Environmental science; Curriculum; Interdisciplinarity; Universities     

Preparation of activated carbons from heavy-oil fly ashes

The use of heavy oil fly ash with high ash content (45 wt.%) as a precursor for the preparation of activated carbons has been investigated. The raw fly ash and the fly ash with lower ash content, obtained by a HCl/HF washing treatment, have been pyrolyzed at 900 degrees C and then activated with CO(2) in the temperature range of 800-900 degrees C for different times. The activated carbons have been characterised as regards the surface area and the pore volume. The evolution of the porosity has been related to the burn-off degree.     

Energy from gasification of solid wastes

Gasification technology is by no means new: in the 1850s, most of the city of London was illuminated by "town gas" produced from the gasification of coal. Nowadays, gasification is the main technology for biomass conversion to energy and an attractive alternative for the thermal treatment of solid waste. The number of different uses of gas shows the flexibility of gasification and therefore allows it to be integrated with several industrial processes, as well as power generation systems. The use of a waste-biomass energy production system in a rural community is very interesting too. This paper describes the current state of gasification technology, energy recovery systems, pre-treatments and prospective in syngas use with particular attention to the different process cycles and environmental impacts of solid wastes gasification.