Experimentelle Untersuchungen zur Ökologie der marinen Kieselalge Thalassiosira rotula. II. Der Einfluß des Salzgehaltes

The effects of salinity (8 to 38‰) on the marine plankton diatom Thalassiosira rotula Meunier were investigated with respect to different temperature and light conditions. Two ecological aspects were examined separately: (1) the effect of various salinities, constant over a long period, was studied using well adapted cultures; (2) mixing processes were simulated by transferring cell chains from water of 33.9 or 20‰ S into lower salinities, as well as from 33.9 into 38‰ S. At 12° and 17°C, growth occurred at salinities from 12 to 38‰. In cold water (6°C), T. rotula did not grow below 16‰ S. Generation time was not influenced by salinities within the tolerance range if adapted cultures were grown under optimal illumination (1000 lux, light-dark cycle of 14:10 h; 12°C) or temperature (17°C; 2000 lux, light-dark cycle of 14:10 h). With increasing illumination or decreasing temperature, the other factors remaining constant, maximum growth rates were obtained with a salinity range of 20 to 32‰. Various salinities affected division rates most obviously if cultures were grown under continuous illumination; the optimum for cell division then ranged from 24 to 28‰ S only. Using adapted cultures again, the effect of different salinities on final cell yield is presumably more intense than their influence on generation time. T. rotula responded to sudden salinity changes only if transferred from water of 20‰ S into lower concentrations and from 33.9 into 38‰ S. Particularly at 12 and 38‰ S, growth rate and colony size (cells per chain) were reduced during the first few days. Increase of generation time and decrease of chain size occur coincidentally. The influence of different salinities on the occurrence of T. rotula in the sea is discussed in conjunction with experimental results on other ecological factors, and the present results are compared with the few available data obtained in nature by other authors. Accordingly, in the sea, a salinity range of 20 to 33‰ should prove optimal for T. rotula, 34 to 38‰ S would presumably represent still adequate conditions, while below 20‰ S T. rotula would probably rarely or never occur.     

Characterising sources and sinks of rural VOC in eastern France

Fifty non-methane hydrocarbons (NMHC) and seventeen carbonyl compounds were measured at a French rural site from 1997 to 2001, as part of the EMEP programme. Data handling was based on an original source-receptor approach. First, the examination of the levels and trends was completed by the comparison of the seasonal distribution of rural and urban VOC/acetylene ambient ratios. This analysis has shown that most of the compounds derived from mixing and photochemical transformation of mid-range transported urban pollutants from the downwind urban area. Then, identified sources and sinks were temporally apportioned. Urban air masses mixing explains, at least, 80% of the wintertime levels of anthropogenic NMHC and isoprene. In summer, photochemistry dominates the day-to-day distribution of anthropogenic NMHC whilst summertime isoprene is also controlled by in-situ biogenic emissions. Then, the results of C(1)-C(3) carbonyls were discussed with respect to their direct biogenic and anthropogenic emissions and photochemical production through the [carbonyl/auto-exhaust tracers] emission ratio. Diluted vehicle exhaust emissions mainly contribute to the total content of lower aldehydes in winter while other processes control lower ketones. Secondary production is predominant in summer with at least a 50% high intensity. Its dependence upon temperature and radiation is also demonstrated. Finally, the importance of the primary and secondary biogenic production of acetone and formaldehyde is assessed. In particular, biogenic contribution would explain 37 +/- 25% of acetone levels in summer.     

Pigeon orientation: effects of the application of magnets under overcast skies

 To verify the existence of a magnetic compass in birds, researchers have often released homing pigeons under overcast skies that are equipped with bar magnets on various parts of their body. In particular, Keeton was successful in finding disorientation in overcast conditions in a first series of tests, but not in a second series. The experiments reported here attempt to explain this contradiction on the basis of findings obtained by releasing pigeons equipped in a way similar to that reported in Keeton's tests and pigeons equipped in a way similar to that reported by other authors. Received: 15 November 1999 / Accepted in revised form: 28 February 2000     

Evaluation of lipid peroxidation as a toxicity bioassay for plants exposed to copper

Agricultural soils may contain toxic levels of copper (Cu) due to sewage sludge spreading or industrial pollution but chemical analyses may not be representative of Cu bioavailability, defined as the soil Cu fraction that plants can actually absorb (i.e. Cu fraction which is not strongly adsorbed to soil components). Lipid peroxidation caused by Cu in plants was investigated as a relevant bioassay of toxicity. Seven-day-old rapeseed plantlets were grown on Cu-supplemented medium in controlled conditions. Lipid-peroxidation was assessed by measuring: (1) the 2-thiobarbituric acid (TBA)-reactive substances; (2) the hydroperoxy acids by HPLC analysis; and (3) the alkane outputs by gas chromatography. We first verified the correlation between the results obtained by each method and then discussed their advantages and disadvantages within the context of a bioassay, showing that the volatile alkane output measurement is the most precise and easy to perform method for this purpose.     

Development of a loading dock safety evaluation tool

INTRODUCTION: Companies that use forklifts to load and unload trucks at loading docks are well aware of the main danger associated with this type of activity (i.e., the possibility of the forklift falling or tipping over when the truck suddenly moves away from the dock). Even if various truck restraint measures can be implemented to reduce the possibility of this type of accident, a number of hazardous incidents that result in a forklift tipping over from a loading dock still do occur regularly in day-to-day activities. This situation has brought experts to examine and evaluate the effectiveness of different measures and systems depending on the context in which they are used. METHODS: The present study touched upon both the technical and the organizational aspects of the restraint measures that could have an impact on safety. Certain elements were examined very closely, especially the failure of mechanical devices and their relation to the environment in which they are used, as well as the systemic interaction between people and the various restraint measures in use in a given context. CONCLUSION: This article presents a safety evaluation tool regarding restraint measures or systems for trucks docked at loading platforms - a tool that, of course, would take into consideration both the specific contextual aspects related to the docking bay itself, and to the plant. IMPACT ON INDUSTRY: This tool is designed to help companies choose the optimal safety measures to implement, while remaining realistic in terms of the technical and economic aspects of any given situation.     

Quantifying sources of climate uncertainty to inform risk analysis for climate change decision-making

Quantitative estimates of future climate change and its various impacts are often based on complex climate models which incorporate a number of physical processes. As these models continue to become more sophisticated, it is commonly assumed that the latest generation of climate models will provide us with better estimates of climate change. Here, we quantify the uncertainty in future climate change projections using two multi-model ensembles of climate model simulations and divide it into different components: internal, scenario and model. The contributions of these sources of uncertainty changes as a function of variable, temporal and spatial scale and especially lead time in the future. In the new models, uncertainty intervals for each of the components have increased. For temperature, importance of scenario uncertainty is the largest over low latitudes and increases nonlinearly after the mid-century. It has a small importance for precipitation simulations on all time scales, which hampers estimating the effect which any mitigation efforts might have. In line with current state-of-the-art adaptation approaches, we argue that despite these uncertainties climate models can provide useful information to support adaptation decision-making. Moreover, adaptation decisions should not be postponed in the hope that future improved scientific understanding will result in more accurate predictions of future climate change. Such simulations might not become available. On the contrary, while planning adaptation initiatives, a rational framework for decision-making under uncertainty should be employed. We suggest that there is an urgent need for continued development and use of improved risk analysis methods for climate change adaptation.     

Pflanzenschutz: Neue Gesetze und ihr Nutzen

The debate about the revision of the EU directive 91/414 has often been characterized by unobjective criticism of the existing regulations and of the authorities involved in the regulatory procedure. This made many consumers feel uncertain and left the public with the impression that the current regulatory system for plant protection products in Europe was not safe for consumers and the environment. However, a detailed evaluation of these statements has clearly demonstrated that the current regulatory procedure is safe and recent scientific knowledge is taken into account. The risk potential calculated for aquatic and terrestrial organisms in Germany has continuously decreased since 1987. The effects and the benefits of the new regulations, which have reached a level of complexity as never before, are discussed in this context. From an industry perspective, clear legal regulations and practical implementations are essential to guarantee the transparence of the regulatory process and predictability of the outcome.     

From environmental data acquisition to assessment of gardeners’ exposure: feedback in an urban context highly contaminated with metals

Environmental Science and Pollution Research - Although growing vegetables in urban gardens has several benefits, some questions in relation with the safety of foods remain when the self-production...