Documents found
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2651.More information
Some 1800 traditional wells and 100 deep boreholes (40 to 65 m depth) contribute to the drinking water supply of Ouagadougou. In order to better know the origin of the mineralization, the concentration trends and to characterize the structure and the functioning of the aquifers, a hydrochemical study has been carried out. The city is located in the Sudano-Sahelian climate zone with a rainy season from June to September and a dry season occurring between October and May. The average rainfall is about 700 mm. The geology of the study area comprises crystalline formations overlain by a layer of weathered materials about 30 m thick. Hydrogeologically, two main aquifers are encountered here: the near surface aquifer located in the laterites and exploited through hand-dug wells, and the deep aquifer consisting of coarse sands and fractured bedrock. The latter aquifer, most of the time confined, is tapped by the boreholes and is isolated from the first by clayey formations.Regarding the chemistry, water from the boreholes shows a bicarbonate calcic and magnesium facies, whereas the well waters are characterized by a chlorinated and nitrate facies with a sodium trend. The dominant process in the deeper aquifer is the hydrolysis of silicates. The near-surface aquifer is highly influenced by superficial supplies. In this case, the mineralization of the anthropogenic organic matter encourages the dissolution of the silicates. The electrical conductivity and the alkalinity, easily measurable in the field, support this suggestion. The nitrate contents exceed WHO norms in nearly 60% of the 1800 inventoried wells. Their statistical analysis in relation to the distances between the different sampling points highlights the heterogeneity of the environment and the localized state of the influence of the anthropogenic supplies, confirming the hydrodynamic concept of a discontinuous environment typical of bedrock zones. The seasonal variations of nitrate concentrations in the wells reflect soil leaching phenomena during the wet season.The stable isotope (18O/2H) content of the waters allowed a differentiation between the wells characterized by evaporation processes and the boreholes showing contents close to multi-year mean values of the monsoon rainfalls. These observations suggest two types of recharge: the first type takes place directly through the weathered mantle and the second type, delayed, occurs through lakes and creeks under evaporation conditions.
Keywords: Pollution urbaine, hydrochimie, aquifères, socle cristallin, Ouagadougou, Burkina Faso, Urban pollution, hydrochemistry, aquifers, crystalline basement, Ouagadougou, Burkina Faso
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2654.More information
This article presents a new relative chronology for the Linearbandkeramik (LBK) of the Meuse basin. Divided into six main phases, the sequence is based on analysis of decorated ceramics from sixteen sites in Belgium and two sites in Holland. Eleven of the Belgian sites are located in Hesbaye, the province with the densest LBK settlement. The other five sites form an outlying group in Hainaut, a little over 100 km to the west. The two Dutch sites are located in southern Limburg, about 50 km north-east of Hesbaye. Fine-ware ceramics were coded for rim, main and intermediate decoration motifs, employing a classification system previously developed in work on the LBK in Lorraine, with particular attention paid to the various techniques used for impressed decoration. The new Meuse basin sequence was established using 165 assemblages containing at least eight decoration motifs, representing a total of 5 101 coded motifs. In a majority of cases, these assemblages were formed by grouping ceramics from lateral pits of houses. Correspondence analysis and hierarchical clustering were used to seriate the assemblages and to define phases and sub-phases. By comparing quantitative trends in decoration motifs, the new Meuse chronology can be synchronized with the Langweiler (Aldenhoven plateau), Lorraine and Seine basin LBK sequences, not only enabling a finer characterization of each regional style but also enhancing the view of interactions between the different groups in the study zone. During the early LBK, the period that sees the first settlements in Hesbaye and north Lorraine, the Flomborn style prevails throughout the Rhine basin. When this cultural entity breaks down, decoration evolves in each region in a different manner. In the middle LBK, the Langweiler area, Dutch Limburg and Belgium form a coherent complex, termed the Rhine-Meuse style, characterized by bands delimited by incised lines and filled with rows of point impressions, which is the majority decoration. In the Moselle basin, as in southern Hessia, the Main style prevails, predominately with bands filled with transverse, crossed or longitudinal incised lines, while in the Seine basin the Champagne region is closely linked in stylistic terms to southern Alsace. The late LBK sees further regional differences, notably with the appearance of the Leihgestern style on the upper course of the Lahn, in central Hessia, and the emergence of the Cologne style in the lower Rhine. The Belgian LBK remains relatively unaffected by these processes and maintains its originality by developing the excessively broad curvilinear motifs, composed of bands filled with incised lines or with multiple-tooth (three or more teeth) comb impressions. These motifs characterize the Omalian style. In north Lorraine, the Main style remains important but the region is now split into two, with on the right bank of the Moselle a strong presence of the Oberrhein-Pfalz style, whose epicentre lies in the Palatinate, and on the left bank a predominance of Omalian influences. These favoured stylistic relations are also reflected by the circulation of lithic raw materials : on the middle and lower course of the Moselle, most of the flint tool-kit is made from blades in Maastrichtian and Campanian flint, imported from the Meuse basin as semi-finished products. In return, one finds in Hainaut, on the site of Blicquy “ Petite Rosière”, Moselle-type motifs in noticeably higher numbers than attested elsewhere in Belgium. In the same period, on the upper course of the Moselle, the LBK of south Lorraine is linked to northern Alsace, while the Champagne LBK maintains its preferential relations with southern Alsace. Throughout the late LBK, there is only limited interaction and exchange between these two groups and the Meuse, lower Rhine and middle Moselle. In the final LBK, the situation is more difficult to assess because the documentation varies in quality from one region to another. At this time, the Langweiler area is apparently abandoned by the LBK, while the Omalian-style LBK still flourishes in Hesbaye and to a lesser extent in Hainaut. On the middle course of the Rhine, new cultural entities appear, with the emergence of the Hinkelstein group on the Neckar and in the northern Palatinate, and the development of the Plaidt style on the lower course of the Moselle, from the Rhine confluence up to Luxembourg. A particular style appears in north Lorraine, derived from the Oberrhein-Pfalz style, while in south Lorraine another original style develops, combining elements from southern and northern Alsace as well as from north Lorraine. In the Seine basin, the LBK spreads northwards and westwards out of Champagne, settling the middle and lower courses of the Aisne and Yonne. Here again, one sees the formation of an original style, characterized by T motifs and predominant use of two-or threetoothed combs, at a time when combs with four or more teeth are more frequently used on the Meuse. At this stage, there is virtually no exchange between the Meuse and the Seine, while the middle Moselle distances itself stylistically from the Omalian but still imports large numbers of blades in Campanian flint from Hesbaye. The preferential relations maintained between Belgium and north Lorraine during the LBK apparently cease in the terminal LBK stage. At this time, the Blicquy-Villeneuve-Saint-Germain (BVSG) culture appears in the Seine basin and in Belgium, possibly slightly earlier in Hainaut than in Hesbaye. The emergence and subsequent development of this new stylistic entity represents a significant change, because there is relatively little evidence for contacts between Belgium and the Seine basin during the previous LBK phases. In the terminal LBK, the Moselle basin finds a new supply of raw material in the Secondary and Tertiary flint of Champagne. The early BVSG site of Reims-Tinqueux shows that this “ economic” exchange is also accompanied by some stylistic interaction.
Keywords: Tyrrhenian area., petrographic analysis, studies of polished and/ or macro-tools, Early and Middle Neolithic, chronologie, Belgique, Bassin de la Meuse, Néolithique ancien, Rubané, décor céramique, sériation, styles régionaux.
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2656.
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2657.More information
Every year the Telethon, organized since 1987 by the French myopathie patients' association (AFM) and the TV channel France 2, brings together researchers, patients, singers and the general public in an immense movement of collective solidarity. This movement is materialized in a flow of donations which amounted to 460 million francs for the year 1998 alone. The money thus collected is used to finance research on neuromuscular diseases, to support patients and their families and to cover costs. The success of this French version of the Telethon, inspired by the US Muscular Distrophy Association, is constantly growing. Apart from two instances where the Telethon was adversely affected by controversy between the organizers and the state, the amount in donations promised during the programme increases every year. Originally a purely televisual event, the Telethon is today deeply rooted in local life in France. Throughout the country, more and more events are organized annually on the ground by the active AFM network, in partnership with diverse local associations. These actions are currently the source of over half of the funds collected.
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2659.
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