Total mercury concentrations in an industrialized catchment, the Thur River basin (north-eastern France): geochemical background level and contamination factors

River bottom sediments and soils were collected from the industrialized Thur River basin (north-eastern France) to assess mercury contamination. The regional geochemical background level of total mercury was evaluated to calculate mercury contamination factors (Fc) in soils and river bottom sediments. Our estimate of the mean background mercury levels in river sediments and soils, not affected by human activities, was 232 ng g1 (range: 27–406 ng g1). Sediments contaminated by the effluent from a chlor-alkali plant yielded the highest contamination factors (Fc¼1784). Contamination factors of surficial soils within 1 km of the industrial site range from 6.3 to 43.6. This contamination is attributed to diffuse atmospheric deposition from this local plant. However, even upstream from this industrial area elevated contamination factors were recorded for river bottom sediments (Fc¼3.2 to 26.4) and for one alluvial soil profile (Fc¼10). This is possibly due to past pollution resulting from waste water discharges. Mercury contamination in the different horizons of alluvial soils is not correlated with soil organic carbon content, but may be the result of occasional accidental pollution arising from the introduction of contaminated suspended particulate matter by the Thur River during periods of flooding

Fluvial trasnports of mercury pollution in the Ill river basin (Northeastern France): pertitioning into aqueous phases, suspended matter and bottom sediments.

The increase and dispersion in aquatic systems of mercury, which is not very abundant in the global environment, are mainly due to the industrial development and intensification of human activities (halogen chemicals, dental and pharmaceutic industries, agriculture, gold mining, etc.). In the Alsace region (northeastern France), the Ill river and one of its tributaries, the Thur, are the most polluted because of industrial wastewaters from the chlorine and soda industry which uses mercury as a cathode in electrolysis

Géochimie et hydrologie des eaux de surface : exemple du bassin du fleuve Congo

Sur la base d'un échantillonnage mensuel sur plusieurs années, on cherche à comprendre les variations temporelles de la qualité chimique des eaux du Congo et à établir les bilans des flux de matières exportées par le fleuve. Différentes techniques d'analyse chimique sont utilisées pour déterminer la composition chimique des eaux: colorimétrie (NH4+ et H4SIO4.), absorption atomique (Na +, K+, Ca2+ et Mg2+), chromatographie ionique (SO42-, NO3- et Cl-) et titration à l'acide (HCO3-). Ces analyses chimiques révèlent la prédominance des ions bicarbonates, du calcium et de la silice parmi les substances minérales dissoutes. Les concentrations des éléments majeurs dissous sont en général diluées pendant les périodes de hautes eaux. Les résultats obtenus après trois années de mesures permettent d'évaluer le flux moyen annuel dissous à 40-44 millions de tonnes

Mercury contents and speciation in soils and river waters of an industrialised catchment, the Thur river basin (Alsace) Contribution of the atmospheric deposition

River water, river sediment and soil samples were collected from the industrialised Thur river basin (north-eastern France) to assess the current extent of total mercury and methylmercury (MeHg) contamination. A high performance liquid chromatography (HPLC) method, coupled with an online Atomic Fluorescence Spectrometry after post colum oxidation of the organomercury compounds by UV light irradiation and cold vapour generation (CV-AFS), was developed for mercury speciation. The regional geochemical background level of mercury has been first evaluated to calculate total mercury contamination factors (CF) in soils and river sediments. It was estimated to 232 ng.g-1 for river sediments and soils not affected by anthropogenic activities. The highest contamination factors have been estimated for the riverine sediments (CF=1 782) receiving the industrial waste effluent of a chlor-alkali plant. Contamination factors of surficial soils located 1km around the industrial site range from 6.2 to 55.3. This contamination could be attributed to diffuse atmospheric deposition from the local industry. Mercury contamination in the different horizons of alluvial soils is not correlated with particulate organic carbon content but rather with historical accidental mercury pollution coming from the deposition of contaminated sediments settled from the Thur river during flood periods. First results on mercury speciation show that the proportion of MeHg in alluvial and industrial soils averages 0.03 to 0.15% of total Hg. Dissolved organic Hg represents the major component of total dissolved Hg in the river water and its proportion (70-100%) is seasonally variable

Dissolved major elements exported by the Congo and the Ubangi rivers during the period 1987-1989

On the basis of monthly sampling during the period 1987- 1989, the geochemistry of the Congo and the Ubangi (second largest tributary of the Congo) rivers was studied in order (1) to understand the seasonal variations of the physico-chemical parameters of the waters and (2) to estimate the annual dissolved fluxes exported by the two rivers. The results presented here correspond to the first three years of measurements carried out for a scientific programme (Interdisciplinary Research Programme on Geodynamics of Peri-Atlantic Intertropical Environments, Operation 'Large River Basins' (PIRAR-GBF) ) undertaken jointly by INSU and ORSTOM planned to run for at least 10 years

Archives de la Grande Guerre

Alors que le centenaire du début de la première guerre mondiale est devenu un véritable phénomène éditorial, les documents historiques et les fonds d'archives relatifs à cette période restent les parents pauvres de cette commémoration. La Grande Guerre et ses conséquences ont pourtant entraîné la production d'une énorme masse de documents, inédite par son ampleur, sa richesse et son caractère novateur. En partenariat avec les ministères de la Défense et des Affaires étrangères, le Service interministériel des Archives de France (ministère de la Culture et de la Communication) a réuni 80 contributeurs, tant universitaires qu'archivistes, pour réaliser ce manuel de recherche sur la première guerre mondiale. Cet ouvrage présente, en 49 contributions thématiques, les acquis de l'historiographie, les perspectives actuelles de la recherche et les sources archivistiques. Il est destiné aussi bien aux chercheurs et érudits qu'aux généalogistes et amateurs désireux de mieux connaître ce moment fondateur du XXe siècle : chacun, qu'il recherche une information ponctuelle, qu'il désire découvrir un sujet neuf pour lui, ou qu'il souhaite disposer d'un état des sources à consulter, pourra recourir à ce livre et y trouver la réponse à ses interrogations