Reconstitution des apports en éléments traces métalliques et bilan de leur migration dans un Luvisol sableux soumis à 100 ans d'irrigation massive par des eaux usées brutes

Raw wastewaters were massively spread on sandy luvisols near Paris from 1899 to 2002, leading to high trace metals (TM) pollution of soils. Mass balance calculations were performed on a soil profile to assess vertical migration of TM. The contamination was estimated by subtracting the natural pedo-geochemical background of the horizons. TM inputs were estimated using Cr as an invariant. It is shown that Pb and Cr remained in the surface horizon, while Ni, Cd, Cu and Zn migrated downward, being more or less trapped depending on the physicochemical properties of the horizons. To cite this article: C. Dère et al., C. R. Geoscience 338 (2006).     

Reindeer management during the colonization of Sami lands: A long-term perspective of vulnerability and adaptation strategies

Reindeer husbandry's strong connection to the land, together with the ongoing climate-change debate, has generated growing interest in its socio-ecological resilience and vulnerability. The ability of indigenous societies and their activities to respond to change is widely recognized to be dependent on several factors, such as socioeconomic forces and aspects of governance, all of which have long historical backgrounds. However, although historians constantly address questions about human societies, there have been very few historical studies on their resilience, vulnerability and adaptation strategies. Here, using historical sources, we analyze the vulnerability of reindeer husbandry (and the Sami societies that depended on it) in Sweden during the 19th century. We demonstrate that although reindeer management was a much more diverse enterprise at that time than it is now, the major adaptation strategy and constraining forces were similar to those of today. The foremost adaptation strategy was, and still is, the flexible use of pasture area, and the clearest constraints during the 19th century were the loss of authority over the land and the imposed regulation of reindeer management-both of which were strongly connected to the process of colonization.

Terminology

Throughout this paper we use the terms reindeer management and reindeer pastoralism interchangeably. Sami reindeer pastoralism has been described as a complex system with two different aspects of management: herding and husbandry. Husbandry has been defined as the accumulations of profit whereas herding has been defined as the control of the animals in the terrain (Paine, 1970, p. 53). In a Swedish context husbandry questions concerning slaughter and castration of reindeer were discussed within the household and herding matters were resolved jointly within the traditional working community Siida. The Siida consisted of households working together on traditional pasturelands and these constellations were grouped together into administrative reindeer pasture districts (Sami villages) ( [Ingold, 1978], [Fellman, 1910] and [Beach, 1981]).     

Contribution of Secondary VOC to the Composition of Aqueous Atmospheric Particles: A Modeling Approach

Measurements show that 20–60% of the carbon mass present in fine atmospheric particulate matter consists of water soluble organic compounds (WSOC). However, only 5–20% of this WSOC has been identified, mainly as dicarboxylic acids. Because of their high solubility in water, multifunctional secondary compounds derived from the gas-phase oxidation of volatile organic compounds (VOC) are suspected to be key contributors to the WSOC. To test this assumption, an estimate of aqueous uptake of secondary VOC was included in a highly detailed gas-phase mechanism which treats explicitly the formation of the secondary VOC from a set of representative primary species. Simulations were conducted for 2 scenarios, representing typical rural and urban areas. It was observed that the uptake of secondary VOC can lead to WSOC mass concentrations in the range of a few C m^–3, in fairly good agreement with typical WSOC mass concentrations measured. Speciation of WSOC was found to be mainly as tri- or higher multifunctional hydroxy-carbonyl species and hydroxy-hydroperoxide-carbonyl species, in urban and rural environments, respectively. However, it was also found that taking into account only the absorption of secondary VOC does not bring the carboxylic acids mass concentration in agreement with measurements. An attempt was made to explain this discrepancy by introducing chemistry occurring within deliquescent aerosols.     

Cementation of kerogen-rich marls by alkaline fluids released during weathering of thermally metamorphosed marly sediments. Part I: Isotopic (C,O) study of the Khushaym Matruk natural analogue (central Jordan)

The Khushaym Matruk site in central Jordan may represent a natural analogue depicting the interaction of alkaline solutions with a clayey sedimentary formation or with clay-rich confining barriers at the interface with concrete structures in waste disposal sites. In this locality, past spontaneous combustion of organic matter in a clayey biomicritic formation produced a ca. 60 m-thick layer of cement-marble containing some of the high-temperature phases usually found in industrial cements (e.g., spurrite, brucite, and Ca-aluminate). A vertical cross-section of the underlying sediments was used in order to study the interaction between cement-marbles and neighbouring clayey limestones under weathering conditions. A thermodynamic approach of the alteration parageneses (calcite–jennite–afwillite–brucite and CSH phases) in the cement-marbles constrains the interacting solutions to have had pH-values between 10.5 and 12. Over 3 m, the sediments located beneath the metamorphic unit were compacted and underwent carbonation. They display large C and O isotopic variations with respect to “pristine” sediments from the bottom of the section. Low δ¹³C-values down to −31.4‰/PDB show the contribution of CO₂ derived from the oxidization of organic matter and from the atmosphere to the intense carbonation process affecting that particular sedimentary level. The size of the C isotopic anomalies, their geometrical extent and their coincidence with the variations of other markers like the Zn content, the structure of organic matter, the mineralogical composition, all argue that the carbonation process was induced by the percolation of high pH solutions which derived from the alteration of cement-marbles. The temperature of the carbonation process remains conjectural and some post-formation O isotopic reequilibration likely affected the newly-formed carbonate. Carbonation induced a considerable porosity reduction, both in fractures and matrixes. The Khushaym Matruk site may have some bearing to the early life of a repository site, when water saturation of the geological formations hosting the concrete structures is incomplete, enabling simultaneous diffusion of alkaline waters and gaseous CO₂ in the near field.     

Dust Formation Chemistry in Carbon-Rich Wolf-Rayet Winds

Dust formation processes are investigated in the hot hydrogen-deficient wind of carbon-rich Wolf-Rayet (WC) stars. Results show that dust precursors (small linear carbon chains) form in large quantities only at high gas densities. This suggests that a clumpy wind or an equatorial disc are necessary to trigger dust formation in WC stars. This revised version was published online in September 2006 with corrections to the Cover Date.     

On the use of long-term observation of water level and temperature along the shore for a better understanding of the dynamics: example of Toulon area,France

Ocean Dynamics - A dense network of instruments has been deployed within harbors along the Mediterranean coast, in the Toulon Metropole area, between the Hyères islands and the Sanary Bay in...