Communities as the agents of commodification: The Kumbo Water Authority in Northwest Cameroon

In 1991 the people of the town of Kumbo in Northwest Cameroon expelled the national water corporation from town by force. They claimed to be retrieving a network that the community rightfully owned and they began to run the system along community lines. The paper tells the story of that water supply twice. First it reproduces the popular accounts that circulated in the 1990s that emphasize the role played by the community in the development and operation of the water supply and portray recent events as a triumph of community management. Then it retells the story using archive evidence that puts a quite different light on some of the events. It is argued that the emphasis on community management has a tendency to obscure other important aspects of the story, for example its political context and consequences. It is suggested that the widespread admiration for any initiative that is community based often results in an uncritical analysis of this form of development project. In this case the commodification of water accelerates after the community has wrested control of this public service from the state.     

Mise en évidence d'un nouveau front de chevauchement dans l'Atlas tunisien oriental de Tunisie par sismique réflexion. Contexte structural régional et rôle du Trias salifère

Structural interpretations of newly acquired seismic lines in northeastern Tunisia allow us to highlight a new thrust front for the Atlasic range of Tunisia, in contrast to the previously Zaghouan fault thrust Dorsale zone. This new thrust front takes place on weakness tectonic zones, materialized by inherited faults anchored on the pre-Triassic basement. This front seems to be a paleogeographic trend controlling structural style and basin fill with a synsedimentary activity. The front is expressed by reverse faults, thrust faults, back thrusting, and decollement structures. To cite this article: S. Khomsi et al., C. R. Geoscience 336 (2004).     

Using stable isotope analyses to assess carbon dynamics in a shallow subtropical estuary

The sources of carbon, which fuel water column respiration, remain unresolved for most estuaries; our objective was to examine carbon dynamics in a shallow subtropical estuary. We sampled the Sabine-Neches estuary, Texas, during low (November 1999) and high (May 2000) freshwater inflow and measured stable carbon isotope ratios of the dissolved inorganic and orgnaic carbon (δ¹³C-DIC, δ¹³C-DOC), as well as quantifying accessory parameters (salinity, nutrients, total suspended solids, and photosynthetic pigments). Pigment analysis indicated that diatoms were the predominant phytoplankton. Data from the May 2000 sampling event exhibited conservative mixing, indicating that the system was acting as a conduit between the watershed and the Gulf of Mexico. During November, mixing was generally nonconservative indicating extensive recycling of allochthonous and autochthonous carbon sources. Our data imply that both carbon sources had similar isotope, ratios that made it impossible to unambiguously determine the dominant source supporting respiration. The nonconservative DIC concentration data indicating an autotrophic sink as well as the strong relationship between δ¹³C-DOC and chlorophylla, suggest that in situ production was an important component of the DOC pool. We hypothesize that uncharacteristically calm wind conditions during sampling may have promoted phytoplankton settling, removing autotrophs, from the water column, but leaving behind a dissolved biogeochemical signature. Interpretation of carbon dynamics may be confounded by spatial and temporal decoupling of producers and consumers from biogeochemical indicators.     

Salinisation des nappes côtières : cas de la nappe nord du Sahel de Sfax,Tunisie

The intensive agricultural and economic activities induce the increase of the risk of groundwater quality degradation through high groundwater pumping rates. The salinization and contamination are the main sources of this pollution, especially in coastal aquifers. The explanation of the origin of salinity for the shallow aquifer of Northern Sahel of Sfax was analysed by a chemical study of the groundwater main compounds. The partitioning of groundwaters into homogenous groups is undertaken by graphical techniques, including a Stiff pattern diagram, an expanded Durov diagram and several binary diagrams. The study indicates the presence of various salinization processes. In the recharge area, salinization is the result of dissolution/precipitation of the aquifer formation material (group I). The irrigation water return and the intensive pumping have been identified as major sources of salinization in the south by direct cation exchange and mixing reactions (groups II and III). The anomaly of high groundwater salinity observed near the Hazeg zone was explained by the presence of a seawater intrusion in this area. This hypothesis is related to the high chloride concentration, to the presence of inverse cation exchange reactions (group IV), and to the piezometric level inferior to sea level. To cite this article: R. Trabelsi et al., C. R. Geoscience 337 (2005).     

Halocinèse précoce associée au rifting jurassique dans l'Atlas central de Tunisie (région de Majoura–El Hfay)

Seismic and sequence stratigraphy analyses, petroleum-well control and surface data studies of the Majoura–El Hfay region in the Central Atlas of Tunisia had led to identify and calibrate Jurassic seismic horizons. Seismic stratigraphic sections, seismic tectonics analyses, isochron and isopach mapping of Jurassic sequences show a differentiated structuring of platform and depocentre blocks limited by deep-seated NE–SW, north–south east–west and NW–SE faults intruded by Upper Triassic salt. The early salt migration seems to have started by the platform fracturing during the Lower Liassic rifting event. These movements are fossilized by thickness variations of Jurassic horizons, aggrading and retrograding onlap and toplap structures between subsiding rim-syncline gutters and high platform flanks intruded by salt pillows and domes. The salt migration is also attested by Middle and Upper Jurassic space depocentre migrations. Around the Majoura–El Hfay study blocks bounded by master faults, Triassic salt have pierced the Cretaceous and Tertiary sedimentary cover in a salt diapir extrusion and salt wall structures. To cite this article: D. Tanfous Amri et al., C. R. Geoscience 337 (2005).     

Preliminary data on chemical changes in the Aral Sea during low-level periods from the last 9000 years

The withdrawal of the Aral Sea tributaries (Amu and Syr Daria) for cultures has led to significant falls of its level and an important increase in its salinity. During the Holocene, a succession of low and high water inputs occurred. Silty deposits correspond to the high levels and carbonates to the low levels. This study makes a distinction between the Syr Daria and the Amu Daria water inputs during low-level periods by using mineralogical and chemical compositions of the carbonates deposits. Waters from the Syr Daria are more sulphatic and have a low iron content in comparison with that of the Amu Daria. The Syr Daria was the major tributary around 7500, 4956 and 970 yr?BP, whereas around 6200 and 3610 yr?BP, inflow also from the Amu Daria is observed. To cite this article: L. Le Callonnec et al., C. R. Geoscience 337 (2005).     

Effects of Enclosure on Plant and Soil Nutrients in Different Types of Alpine Grassland

Enclosure is one of the most widely used management tools for degraded alpine grassland on the northern Tibetan Plateau, but the responses of different types of grassland to enclosure may vary, and research on these responses can provide a scientific basis for improving ecological conservation. This study took one site for each of three grassland types (alpine meadow, alpine steppe and alpine desert) on the northern Tibetan Plateau as examples, and explored the effects of enclosure on plant and soil nutrients by comparing differences in plant community biomass, leaf-soil nutrient content and their stoichiometry between samples from inside and outside the fence. The results showed that enclosure can significantly increase all aboveground biomass in these three grassland types, but it only increased the 10-20 cm underground biomass in the alpine desert. Enclosure also significantly increased the leaf nutrient content of the dominant plants and contents of total nitrogen (N), total potassium (K), and organic carbon (C) in 10-20 cm soil in alpine desert, thus changing the stoichiometry between C, N and P (phosphorus). However, enclosure significantly increased only the N content of dominant plant leaves in alpine steppe, while other nutrients and stoichiometries of both plant leaves and soil did not show significant differences in alpine meadow and alpine steppe. These results suggested that enclosure has differential effects on these three types of alpine grasslands on the northern Tibetan Plateau, and the alpine desert showed the most active ecological conservation in the responses of its soil and plant nutrients.