Parametrization of groundwater quality of the Quaternary aquifer in N’Djamena (Chad), Lake Chad Basin: application of numerical and multivariate analyses

The urban groundwater of the Quaternary aquifer of the Lake Chad basin in N’Djamena has been subject to many hydrochemical studies. However, the results are often not presented in a way that enables water quality managers to make an appropriate decisions, which restrict development and poverty reduction efforts. The objective of the present study was to contribute the improved management of the local groundwater resources. A total of 85 groundwater samples were interpreted using hydrochemical techniques associated with integrated numerical indices and multivariate statistical analysis. The hydrochemical results coupled with the relative residence time of water have shown that the chemical composition of these waters is linked to geogenic and anthropogenic factors and to their proximity to the Chari-Logone rivers. These investigations showed that the groundwater quality in N’Djamena is characterized by a high spatial variability. This study also assessed the suitability of groundwater for user needs and identified areas which are more/less favorable for a specific use. The evaluation of water quality and its suitability for human consumption is also a problem of optimizing data acquisition strategy, and this study used the correlation between water quality index (WQI) and electrical conductivity (EC) to orientate future data acquisition strategies. This parametrization can assist the decision makers and water management professionals in evaluating groundwater availability and setting up a robust water quality management plan in areas with similar hydrogeological and climatic conditions.

     

Photodegradation of the herbicide goal

Photodegradation products of the herbicide Goal active ingredient were obtained with a xenon lamp and analyzed using direct inlet mass spectrometry, MS/MS and GC/MS. A number of products were identified and their generation pathways were established to be mainly Ar—O bond cleavage, dechlorination and photocyclisation. The latter process gives chlorinated and unchlorinated dibenzofurans some of which may be toxic.     

Workload and psychological strain: A test of the French,Rodgers, and Cobb hypothesis

This study of a random sample of self-employed and non-self-employed dentists tests the French, Rodgers, and Cobb (1974) hypothesis, which predicts a curvilinear relationship between psychological strain and person-environment fit. Self-employed dentists had lower strain scores (based on measures of job satisfaction and self-esteem) and greater congruency in P-E fit (based on comparisons of preferred and typical hours in practice) than dentists who were not self-employed. The relationship between strain and P-E fit among self-employed dentists was curvilinear. Both self-esteem and job satisfaction were higher for dentists with a congruent fit between typical and preferred workload and lower for dentists with incongruent fit.     

Effectiveness of creativity training and its relation to selected personality factors

This exploratory study assesses the effectiveness of the Creative Problem Solving Program (Parnes, Noller and Biondi, 1977) for increasing the ideational fluency, flexibility and originality of trainees in a Master of Business Administration program. Pre- and post-training performances of trainees (N = 32) on the Torrance Tests of Creative Thinking (verbal) are compared with a control group of MBA students (N = 44). Compared to the control group, trainees demonstrate significant gains in originality. While both groups show an improvement in fluency. Trainees with high preferences for achievement and dominance but low preference for deference are less likely than average to self-select for creativity training. Performance in a creativity project is positively related to preference for autonomy and creative ability, and negatively related to preference for achievement. Implications of these findings for the effectiveness of creativity training and the attitudes and performance of high need achievers are discussed. Finally, we discuss issues in the generalization and transfer of training to non-training domains.     

Trait synergisms and the rarity, extirpation, and extinction risk of desert fishes

Understanding the causes and consequences of species extinctions is a central goal in ecology. Faced with the difficult task of identifying those species with the greatest need for conservation, ecologists have turned to using predictive suites of ecological and life-history traits to provide reasonable estimates of species extinction risk. Previous studies have linked individual traits to extinction risk, yet the nonadditive contribution of multiple traits to the entire extinction process, from species rarity to local extirpation to global extinction, has not been examined. This study asks whether trait synergisms predispose native fishes of the Lower Colorado River Basin (USA) to risk of extinction through their effects on rarity and local extirpation and their vulnerability to different sources of threat. Fish species with "slow" life histories (e.g., large body size, long life, and delayed maturity), minimal parental care to offspring, and specialized feeding behaviors are associated with smaller geographic distribution, greater frequency of local extirpation, and higher perceived extinction risk than that expected by simple additive effects of traits in combination. This supports the notion that trait synergisms increase the susceptibility of native fishes to multiple stages of the extinction process, thus making them prone to the multiple jeopardies resulting from a combination of fewer individuals, narrow environmental tolerances, and long recovery times following environmental change. Given that particular traits, some acting in concert, may differentially predispose native fishes to rarity, extirpation, and extinction, we suggest that management efforts in the Lower Colorado River Basin should be congruent with the life-history requirements of multiple species over large spatial and temporal scales.     

Karst aquifers on small islands—the island of Olib, Croatia

Water supply is a major problem in the Adriatic islands, especially during the summer tourism season, and represents a limiting factor to the islands' further economic development. Much attention has been given to water supply solutions, primarily in terms of attempting to use the existing island water. Unfortunately, few islands have favourable hydrological conditions to accumulate significant quantities of surface water or groundwater. In the period from 2001 to 2004, investigations were conducted on many islands to define their own freshwater or partially brackish water resources since desalinisation technology could resolve a significant part of the water supply demand on small and distant islands. Due to the specificity and complexity of research in karst areas, the study was conducted in phases and included the geological and hydrogeological reconnaissance of the island, aimed at locating possible areas on the island where the necessary quantities of groundwater of adequate quality could be captured; a detailed hydrogeological mapping of the specified areas, geophysical investigation and test drilling; and, over several days, test pumping of the most promising borehole. One of the islands investigated was the island of Olib. The conducted surveys indicated that it is possible to pump about 3.5 L/s of groundwater from the karst aquifer of the island of Olib, which fully complies with the sanitary quality of drinking water.     

IMPACTS OF CLIMATE CHANGE ON AQUATIC ECOSYSTEM FUNCTIONING AND HEALTH1

ABSTRACT: We review published analyses of the effects of climate change on goods and services provided by freshwater ecosystems in the United States. Climate-induced changes must be assessed in the context of massive anthropogenic changes in water quantity and quality resulting from altered patterns of land use, water withdrawal, and species invasions; these may dwarf or exacerbate climate-induced changes. Water to meet instream needs is competing with other uses of water, and that competition is likely to be increased by climate change. We review recent predictions of the impacts of climate change on aquatic ecosystems in eight regions of North America. Impacts include warmer temperatures that alter lake mixing regimes and availability of fish habitat; changed magnitude and seasonality of runoff regimes that alter nutrient loading and limit habitat availability at low flow; and loss of prairie pothole wetlands that reduces waterfowl populations. Many of the predicted changes in aquatic ecosystems are a consequence of climatic effects on terrestrial ecosystems; shifts in riparian vegetation and hydrology are particularly critical. We review models that could be used to explore potential effects of climate change on freshwater ecosystems; these include models of instream flow, bioenergetics models, nutrient spiraling models, and models relating riverine food webs to hydrologic regime. We discuss potential ecological risks, benefits, and costs of climate change and identify information needs and model improvements that are required to improve our ability to predict and identify climate change impacts and to evaluate management options.