Effect of diffuse recharge and wastewater on groundwater contamination in Douala,Cameroon

High water demand for domestic use in Douala with over 3 million inhabitants is met mainly by shallow groundwater. Field measurements and water sampling in January 2015 were carried out to examine the major controls on the groundwater composition and spatial view of ions in the water, timing of recharge and link between the recharge process and quality of the water. Fifty-two water samples were analysed for major ions and stable hydrogen and oxygen isotopes. Low pH values (3.61–6.92) in the groundwater indicated an acidic aquifer; thus, prone to acidification. The dominant water type was Na–Cl. Nitrate, which exceeded the WHO guide value of 50 mg/l in 22% of the groundwater, poses a health problem. Mass ratios of Cl^?/Br^? in the water ranged from 54 to 3249 and scattered mostly along the mixing lines between dilute waters, septic-tank effluent and domestic sewage. A majority of the samples, especially the high NO₃ ^? shallow wells, clustered around the septic-tank effluent-end-member indicating high contamination by seepage from pit latrines; hence, vulnerable to pollution. Stable isotopes in the groundwater indicated its meteoric origin and rapid infiltration after rainfall. The δ¹⁸O values showed narrow ranges and overlaps in rivers, springs, open wells and boreholes. These observations depict hydraulic connectivity, good water mixing and a homogeneous aquifer system mainly receiving local direct uniform areal recharge from rainfall. The rapid and diffused recharge favours the leaching of effluent from the pit toilets into the aquifer; hence, the high NO₃ ^? and Cl^? in shallow wells. Silicate weathering, ion exchange and leaching of waste from pit toilets are the dominant controls on the groundwater chemistry. Drilling of deep boreholes is highly recommended for good-quality water supply. However, due the hydraulic connection to the shallow aquifer, geochemical modelling of future effects of such an exploitation of the deeper aquifer should support groundwater management and be ahead of the field actions.     

Marine biodiversity and ethnobiodiversity of Bellona (Mungiki) Island, Solomon Islands

This paper reports on the marine biodiversity and ethnobiodiversity of Bellona, a small island in Solomon Islands inhabited by Polynesians who have, for centuries, depended on biodiversity for their own sustainability. The Bellonese have names for at least 8 whales and dolphins, 7 reptiles, over 500 finfish, 191 molluscs, 48 crustaceans, 29 echinoderms and a range of corals, other invertebrates and marine plants, most of which have commercial, subsistence or cultural value. If conserved, this inheritance will continue to provide a foundation for continuing sustainability in a rapidly globalizing world. The paper highlights the importance of the preservation, and application to development, of ethnobiodiversity for food and subsistence security, and contingent issues of conservation and sustainability in small island developing states. As the current extinction crisis escalates globally, the rate of attrition of the intangible indigenous knowledge that has coevolved with this threatened biodiversity is probably far greater. In itself, the recording of information on biodiversity and related sustainable livelihoods is not sufficient to ensure sustainability. There is a vital need to integrate this into the formal education system and applied scientific activities at all levels to achieve the right balance between agriculture, wild harvest and trade, upon which sustainability and subsistence affluence still depend.     

Scattering of magnetic fabrics in the Cambrian alkaline granite of Meruoca (Ceará state,northeastern Brazil)

Anisotropy of magnetic susceptibility (AMS) applied to an alkaline granite from Meruoca (NE Brazil) recorded weak anisotropies, typically below 4%, and a considerable dispersion of the AMS axes. Red-clouded feldspars and clots of metasomatic minerals enclosed in magmatic crystals indicate that hydrothermal fluids altered the granite. U–Pb isotopic data show high-common Pb on zircons but allowed the calculation of a mean SHRIMP age of 523 ± 9 Ma attributed to the magmatic crystallization. Growth of fine oxides by late fluid–rock interactions was responsible for the scattering of AMS. Rock magnetic data indicate they consist mainly of an oxidized magnetite and (titano)hematite. Shape preferred orientation of mafic aggregates measured in granite quarries shows that the pluton preserves a gently dipping magmatic foliation. AMS in some quarries with a well-defined magmatic fabric, however, remains highly dispersed. When AMS mimics the mafic shape fabric, only magnetic foliations share a common orientation. Locally, AMS grounded in coarse Ti-poor magnetite associated with titanite develops a consistent subhorizontal oblate fabric that agrees with tectonic models suggesting that the cupola of the pluton has been exposed by erosion.     

Combining Organic Matter Source and Relative Trophic Position Determinations to Explore Trophic Structure

Stable isotope ratios of carbon and sulfur were used to assess organic matter utilization of numerically abundant consumers present in Apalachicola Bay, FL, USA. These results were used to infer nitrogen isotopic enrichment of organic matter sources in an effort to establish baseline δ ¹⁵N enrichment for trophic evaluations. We compared results from concentration-independent and concentration-dependent mixing models and found that the two methods resulted in widely different conclusions about the importance of organic matter sources that varied ninefold in sulfur concentrations. Nitrogen isotopic enrichment was used to determine relative trophic positions of consumer organisms. Source elemental concentrations of nitrogen were also considered in the calculation of relative trophic levels in a concentration-dependent approach. Concentration-independent and concentration-dependent methods of calculating trophic results were compared. While relative trophic levels of individual species varied continuously from approximately 1.7 to 3.5, comparisons of trophic level among consumers indicated four possible trophic groupings. Filter feeders (mussels and oysters) made up the lowest trophic tier while teleost fishes made up the highest trophic tier. Invertebrates sampled were assigned intermediate nondiscrete trophic levels. Because δ ¹⁵N values of important organic matter sources in the system were similar, the concentration-independent and concentration-dependent methods did not result in significantly different conclusions about trophic level for any of the consumers examined. However, a comparison of the two methods applied to a hypothetical case found that differences in base δ ¹⁵N values ranging approximately 4‰ resulted in significantly different trophic-level assignments when comparing the concentration-dependent and concentration-independent methods of trophic-level calculations. Our results confirm that consideration of the elemental concentrations of the base organisms is an important factor in determining source contributions and may affect trophic-level calculations in systems with a sufficient range of base nitrogen enrichment. However, this result depended on the relative isotopic signatures of the chosen sources and their elemental concentrations and should be considered individually for each system.     

Electrochemical Ozone Production as an Environmentally Friendly Technology for Water Treatment

Perspectives, advances and environmental aspects concerning electrochemical ozone production applied to water purification are presented and discussed in relation to the conventional corona process (silent electric discharge). Ozone generated using a laboratory‐made electrochemical reactor was applied for the discoloration/degradation of dyes used in the Brazilian textile industry and for degradation of endocrine disruptors. A constant ozone load of 0.35 ± 0.02 g/h was used throughout. The study, concerning color removal from dye solutions, revealed that total discoloration is rapidly achieved. The degradation rate of the textile dyes evaluated by TOC is little affected by the dye composition and considerably influenced by the pH and ozonation time. Analysis of the COD/TOC‐ratio indicates that ozonation increases oxidation feasibility of the organic matter (dye by‐products) when compared to the original compounds. Ozonation of mixed aqueous solutions containing different endocrine disruptors revealed these compounds are totally degraded with a very high removal rate.     

Implications of dissected drift at Stockdale Head,western Lake District,northern England

From mapping and consideration of prominent drift ridges at Stockdale Head, western Lake District, northern England it is inferred that the ridges are the products of dissection of a glacigenic or soliflual drift sheet rather than landforms constructed at the margins of a Loch Lomond Stade (LLS) valley‐head glacier. This proposal has implications for the recognition of LLS glacier limits and, possibly, understanding the dearth of moraine ridges associated with Dimlington ice in Lake District valleys. Copyright © 2004 John Wiley & Sons, Ltd.     

The Role of Multiphase Chemistry in the Oxidation of Dimethylsulphide (DMS). A Latitude Dependent Analysis

A kinetic model for the OH-initiated homogeneous gas phase oxidation of dimethylsulfide (DMS) in the atmosphere (Saltelli and Hjorth, 1995), has been extended here to include the liquid phase chemistry. The updated model has then been employed to predict the temperature dependency of the MSA/nss-SO42- ratio. Model predictions have been compared with observational data reported in Bates et al. (1992). Sensitivity and uncertainty analysis has been performed in a Monte Carlo fashion to identify which are the important uncertainties on the input parameters and which are the possible combinations of parameter values that could explain the field observations. Results of the analysis have indicated that the temperature dependencies of the interactions between gas phase and liquid phase chemistry may to a large extent explain the observed T-dependence of the MSA/nss- SO42- ratio. The potential role of multi-phase atmospheric chemistry, not only in the case of SO2 but also of other oxidation products of DMS and, particularly, of DMS itself, has been highlighted.     

Permeability Upscaling Measured on a Block of Berea Sandstone: Results and Interpretation

To physically investigate permeability upscaling, over 13,000 permeability values were measured with four different sample supports (i.e., sample volumes) on a block of Berea Sandstone. At each sample support, spatially exhaustive permeability datasets were measured, subject to consistent flow geometry and boundary conditions, with a specially adapted minipermeameter test system. Here, we present and analyze a subset of the data consisting of 2304 permeability values collected from a single block face oriented normal to stratification. Results reveal a number of distinct and consistent trends (i.e., upscaling) relating changes in key summary statistics to an increasing sample support. Examples include the sample mean and semivariogram range that increase with increasing sample support and the sample variance that decreases. To help interpret the measured mean upscaling, we compared it to theoretical models that are only available for somewhat different flow geometries. The comparison suggests that the nonuniform flow imposed by the minipermeameter coupled with permeability anisotropy at the scale of the local support (i.e., smallest sample support for which data is available) are the primary controls on the measured upscaling. This work demonstrates, experimentally, that it is not always appropriate to treat the local-support permeability as an intrinsic feature of the porous medium, that is, independent of its conditions of measurement.     

The evolution of isolated active regions

The decay of several active regions which emerged early in cycle 22 has been studied using daily magnetograms and synoptic plots obtained at the Vacuum Telescope at the National Solar Observatory, Kitt Peak. The observed patterns are compared with simulations using the flux transport equation and some discrepancies are noted. For one region it is shown that, by including the emergence of a non-random pattern of small magnetic bipoles during the decay, the correspondence between the observed and simulated patterns may be improved.     

The Use of Storytelling for Understanding Women's Desires to Tan: Lessons from the Field

This paper presents reflections on a research project in women's health, providing both substantive findings surrounding tanning and social status and methodological recommendations for future research. The project under review utilized a picture-elicited storytelling method to: a) understand how women link tanned, bronzed skin to health, status, and attractiveness; and b) test the effectiveness of picture-elicited storytelling as a research method. The project found that, when tanning, women use their bodies to inscribe the social norm of the bronzed aesthetic. While women indicate considerable knowledge of the health dangers of tanning, they continue to link tanned skin to beauty, status, and attractiveness. Further, the research project found that the use of picture-elicited storytelling as a method is potentially powerful but requires considerable attention to concerns of power and representation on the part of the research team.