Vosges Mountains Research Articles

Seasonality of mean and heavy precipitation in the area of the Vosges Mountains: dependence on the selection criterion

ABSTRACTThe seasonal distribution of mean precipitation and heavy rainfalls during 1960–2013 was analysed based on daily precipitation totals from 168 rain gauging stations in the Vosges Mountains area, north‐eastern France. Concerning mean precipitation, an ancient Hrudička's index designed as a half‐time of precipitation during a year, surprisingly well expresses the seasonality of precipitation and its clear correlation with the mean annual totals in the studied region. The annual course of mean precipitation leads to a distinction of four groups of stations with respect to the position of stations: MT, mountainous stations with maxima of precipitation in winter and an overall highest mean annual totals; LSp, stations situated on leeward slopes of the Vosges Mountains with two maxima of precipitation (primary in winter and secondary in summer); URP, leeward stations located in the Upper Rhine River Plain with the most humid summer season, and the lowest mean annual totals; WSd, windward stations not influenced by the Vosges Mountains, with relatively evenly distributed precipitation, and slight maxima in autumn.For the heavy precipitation, 1–10‐days totals have been considered to be ‘heavy’ subsequent to applying the three common methods – peaks over threshold (POT), block maxima (BM), and return period estimates based on generalized extreme value distribution. Varying criteria have been employed. The BM method for annual maxima indicates that the heavy rainfall generally occurs during the most humid season although it can also occur anytime during the year. The POT and return period estimates methods reveal that the seasonality of extremes is threshold‐dependent and that probably the threshold sensitivity is also related to the degree of orographic influence – higher occurrence of summer events in the lee while lesser occurrence of winter events in mountains, at higher threshold and shorter duration of event.

Variable water‐saturated areas and streamflow generation in the small Ringelbach catchment (Vosges Mountains, France): the master recession curve as an equilibrium curve for interactions between atmosphere, surface and ground waters

AbstractIn the small Ringelbach research catchment, where studies on the water cycle components in a granitic mountainous environment have been conducted since 1976, the water‐saturated areas that are hydraulically connected to the outlet play a major role in the streamflow generation, as it is here that complex interactions between atmosphere, surface and ground waters take place. During baseflow recession periods, which may last several months between two groundwater recharge events, the atmospheric inputs of water and energy on these contributing areas only explain the streamflow fluctuations observed around the master recession curve, which defines the groundwater contribution: fluctuating above it in the case of precipitation input on these areas, below it in the case of evaporation output from these areas. Streamflow may therefore largely deviate from the master recession curve in the case of long, hot, dry spells.Detailed mapping has shown that their variable extent is well related to baseflow by a loglinear curve. On the other hand, a synthetic master recession curve, well fitted by a second‐order hyperbolic function, has been obtained from numerous pure recession periods. Both based on these two curves, a simple procedure and a simple model have been used to (i) validate the hypothesis that the connected saturated areas are the only permanent variable contributing areas and (ii) simulate the daily streamflow volumes over long baseflow recession periods by a water balance of the aquifer below these areas only. The storm runoff ratio for small to moderate rainfall events is indeed corresponding to the catchment saturated fraction at that time. The volume of daily streamflow oscillations is indeed corresponding to the evaporation at the potential rate from the saturated areas only. In both cases, streamflow naturally tends towards the master recession curve after the end of any atmospheric perturbation. Introducing these findings into TOPMODEL led to significantly improved simulation results during baseflow recession periods.The master recession curve may therefore be considered as a dynamic equilibrium curve. Together with the relationship between saturated extent and baseflow, it provides the main characteristics necessary to understand and model the interactions at this complex interface and the resulting daily streamflow variations during baseflow recession periods in this type of catchment. Copyright © 2016 John Wiley & Sons, Ltd.

Past mining activities in the Vosges Mountains (eastern France): Impact on vegetation and metal contamination over the past millennium

Coring was carried out in a soligenous marsh in the Vosges Mountains in the past mining district of Sainte-Marie-aux-Mines (eastern France). High-resolution palynological, non-pollen-palynomorph, and geochemical analyses were performed along the core. Correlations between the herbal composition of the landscape and trace metals in the core reveal a specific palynological pattern during mining activities. Two main periods of anthropogenic impacts on vegetation and trace metal contamination are shown: during the 16th–17th centuries, for mining and smelting activities, and the beginning of the 20th century, for smelting and the Industrial Revolution. No drastic deforestations occurred near the study site, contrary to historical descriptions and prints of the valley. Controlled forest practices were implemented from the beginning of the record, that is, since cal. AD 1000, so the impact of mining activities seems to be less significant than expected near mining sites. We demonstrate that the minerotrophic characteristics of the record closest to past mining sites allows for (1) the description of the landscape associated with anthropogenic activities and (2) the recording of past trace metal emissions without post-depositional mobility.

Palaeo-pollution from mining activities in the Vosges Mountains: 1000 years and still bioavailable

Mining and smelting activities have contaminated the environment with trace metals (TMs) at a worldwide scale for at least two millennia. A combination of chemical approaches and active biomonitoring was performed to analyse the environmental availability and bioavailability of TM palaeo-pollution in a former PbAg mining district in the Vosges Mountains, France. Along a soil TM contamination gradient that covered eight stations, including two archaeological mining sites, the toxicokinetics of six TMs (Pb, Cd, As, Ag, Co, Sb) in the snail Cantareus aspersus revealed that palaeo-pollution from the studied sites remains bioavailable. This study provides the first data on the accumulation kinetics of Ag and Co for C. aspersus. The environmental availability of the TMs was estimated with three chemical extraction methods (aqua regia, EDTA 50 mM, CaCl2 10 mM). Univariate regression analyses showed that EDTA extraction is the best method for estimating the bioavailability of Pb, As, Ag, Co and Sb to snails. None of the three extractants was efficient for Cd. A multivariate analysis of bioaccumulation data revealed that TM bioavailability and transfer were modulated by exposure sources (soil, humus and vegetation) rather than by soil physico-chemical characteristics. Hence, although the deposition of mining wastes dates back several centuries, these wastes still represent a source of contamination that must be considered to develop relevant site management and environmental risk assessment.

New data on Late Pleistocene small vertebrates from northern France

Quaternary small vertebrate assemblages from northern France, and more generally from northwestern Europe, are poorly recognized, and studied less than those from more southern, Mediterranean areas. However, important sites of human occupation are often found in these northern areas, with significant issues related to the occupation of these sites by Neanderthals and previous humans, as well as faunal dynamics under climatic pressure. In this paper, we present preliminary results from the study of small vertebrate assemblages from two Late Pleistocene sites of northern France: Mutzig (Alsace) and Le Rozel (Normandy). Both are ancient rock-shelters that have been excavated recently and have yielded evidence of Neanderthal occupation, but in very different contexts: Le Rozel is located in a coastal area of northwestern France contemporaneous with a temperate period, while Mutzig is located at the foot of the Vosges mountains in northeastern France and was occupied during a cold period. Consequently, even if these two sites are chronologically close to each other, differences in faunal composition are observed and discussed in relation to the geographic, climatic and biochronological context, in comparing the results from small vertebrates with those from other disciplines (numerical dating, large mammals).

Magnesium Isotope Variations to Trace Liming Input to Terrestrial Ecosystems: A Case Study in the Vosges Mountains.

Liming with Ca and Mg carbonates is commonly used to reduce soil and stream acidity and to improve vegetation growth and nutrition in forests. Ten years ago, dolomite lime was experimentally applied to a forest catchment on granite in the Vosges Mountains (northeast France), which is characterized by acid soils and drained by an acid stream. The average Mg isotope composition of the dolomite lime (-1.75‰) was low compared with that of tree foliage (-0.70‰), granite and deep soil layers (-0.40‰), and stream water (-0.80‰) in the control catchment. After liming, the exchangeable Mg concentrations in surface soil layers, which were initially very low, increased, and the Mg isotope composition decreased (up to -0.60‰). The decrease was smaller in deeper layers but not in proportion to the increase in exchangeable Mg content, suggesting contributions from mineralization of organic matter and/or displacement of exchangeable Mg from surface layers. Before application, Mg concentration in beech and fir leaves was low, and that of 1-yr-old fir needles was lower than that in current needles. Internal Mg translocation within fir needles also resulted in a lower δMg of older needles. Three years after dolomite application, the Mg isotope composition of plant leaves was lower than that in the control catchment; this decrease (up to -1.00‰) was attributed to direct uptake of Mg from dissolving dolomite. Liming doubled the concentration of Mg in the stream, whereas the Mg isotope composition decreased correspondingly from -0.80 to -1.20‰, indicating a fast transfer of dolomite Mg to the stream. Our findings indicate that monitoring of δMg may be a promising tool to study the fate of dolomitic inputs in terrestrial and aquatic ecosystems.

Cartophilia: Maps and the Search for Identity in the French-German Borderland by Catherine Dunlop

Reviewed by: Cartophilia: Maps and the Search for Identity in the French-German Borderland by Catherine Dunlop Kory Olson Catherine Dunlop. Cartophilia: Maps and the Search for Identity in the French-German Borderland. Chicago: Chicago UP, 2015. 257 pp. Catherine Dunlop’s Cartophilia provides a thorough political and historical examination into the borderland and the shifting jurisdictional authority of Alsace-Lorraine in the decades around the Franco-Prussian War. Dunlop focuses her work on the creation of the man-made border between France and Germany along with its cartographic constructions and portrayals. Dunlop divides her book into two sections. The first half, “Mapping Borders,” examines the State’s role in the creation of international borders, most particularly the one established after French defeat in 1871. Her first three chapters provide a useful summary of state-based cartography in France and Germany throughout the nineteenth century, as the two nations began to map their domestic territories. For example, German states benefited considerably from French surveyors who followed Napoleonic military campaigns into their conquered lands. Dunlop also devotes energy to the general understanding of international boundaries prior to the Franco-Prussian War, where any demarcation of a French/German divide would extend well beyond the official state-sanctioned border. As for the period directly following the 1871 Treaty of Frankfurt, Dunlop excellently describes the collaborative approach between French and German officials as they marked, measured, and described the French-German border in the Vosges Mountains. We also learn more about the actual construction of the border itself. For countries such as France that traditionally referred to “natural” borders, such as mountains or water, the establishment of this artificial one (especially upon defeat to a neighbor) pleased few. Other examples of cartography appear in this first half of Dunlop’s volume as well. Maps of language zones created symbolic ruptures between European peoples, suggesting to viewers a correlation between linguistic divides and national borders (52). This trend took place primarily in Germany, where the idea of uniting German speakers even had its own vocabulary for language-specific divisions: Sprachgebeit (language area). [End Page 147] Furthermore, in the nineteenth-century desire for German unification, language maps became idealized spaces for nationalists to visualize how far the future borders of the German state should extend (75). So “seeing” Alsace and German-speaking Lorraine as part of a greater German Empire was more or less expected outre-Rhin. The second half of Dunlop’s book, Borderland Maps for Everyday Life, turns away from scientific maps in favor of “everyday use” ones that constructed up-close, experimental, and emotional views of land. Located far from the “center” of both the France republic and German empire, residents in Alsace-Lorraine related much more to their own medieval villages than to Paris or Berlin. So to be successful, new cartographers needed to acknowledge this mentality. Dunlop demonstrates how mapmakers transformed villages into positive picturesque locations through the use of cadastral maps, which included illustrations and cartouche boxes (text boxes) containing decorative images of the Alsatian countryside, while both nations were creating government-sanctioned visual representations of Alsatian hometowns. Wall maps, too, took on new importance during this time. In contrast to France, which tended to promote the nation or its capital city on classroom walls or in texts such as Le Tour de la France par deux enfants, Germany championed the local in its wall maps, which placed the student’s hometown within the territorial units of the German Empire. In addition to being able to situate their villages visually in relation to other provinces, students were given the opportunity to draw maps themselves in order to familiarize themselves with the shape of the region and to recognize their village’s role within that region. Beyond classroom materials, hiking maps and visual panoramas also help shed new light on the physical changes that the French and Germans imposed on their border territories during the nineteenth and twentieth centuries (133). On the French side, private civil societies helped catalogue the historical and picturesque sites in the Vosges as part of their inclusion into national patrimony. Although the government provided funds, private societies did the work and documented what they found...

Geochemical and isotopic (Sr, U) monitoring of soil solutions from the Strengbach catchment (Vosges mountains, France): Evidence for recent weathering evolution

This study presents the results of a geochemical and isotope (U and Sr) study of soil solutions from two experimental sites in the Strengbach catchment, one under spruce trees and the other under beech trees. The soil solution data, combined with the data from soil and vegetation samples, indicate that the “dissolved” U (filtered to 0.45μm) in the soil solutions is primarily of lithogenic origin, implying that the colloidal U is secondarily associated with organic matter or organo-metallic complexes present in the soil solutions. The uranium activity ratios and Sr isotope ratios of soil solutions are used to decipher the nature of the minerals that control the lithogenic contribution to the soil solutions. A comparison of soil solution data collected over the period 2004–2006 with those collected over the period 1993–2010 indicates a decrease in the Ca and K exported by the soil solutions between 1998 and 2004 at the spruce site and a significantly smaller decrease at the beech site. In addition, the Sr isotope ratios of the soil solutions vary significantly between these two periods at the spruce site but not or much less at the beech site. Such observations suggest that the forest ecosystem at the spruce site is in a transient state associated with recent changes in weathering reactions. The data also suggest that the comparison of U and Sr isotopes in soil solutions and plant samples could be a relevant method for determining whether a forest ecosystem is in a steady or transient state.

Cytotype distribution and phylogeography ofHieracium intybaceum(Asteraceae)

Using flow cytometry and amplified fragment length polymorphism (AFLP), we explored the cytogeography and phylogeography of Hieracium intybaceum, a silicicolous species distributed in the Alps and spatially isolated in the Vosges Mountains and the Schwarzwald Mountains. We detected two ploidies, diploid and tetraploid, but no triploid or mixed-ploidy populations. Whereas diploids are sexual and distributed all across the Alps, tetraploids are apomictic and seem to be confined to the western Alps and the Vosges. We detected a low level of genetic variation. Bayesian clustering identified four clusters/genetic groups, which are partly congruent with the ploidal pattern. The first two groups consisting exclusively of diploids dominate the whole distribution range in the Alps and show east–west geographical separation with a diffuse borderline running from eastern Switzerland to the eastern part of North Tyrol. The third genetic group lacks a defined geographical range and includes diploid and tetraploid plants. The last genetic group comprises tetraploid plants in the French Alps and the Vosges. We suppose that diploids colonized the deglaciated areas from source populations most likely located mainly in the southern part of the recent distribution range and occasionally also in the western Alps. Gene flow and further differentiation likely took place. Apomictic tetraploids most likely originated in the western Alps or in the refugium at the south-western foot of the Alps. Their rather limited geographical range (partly contrasting with the theory of geographical parthenogenesis) can be explained by their rather recent origin. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 179, 487–498.

French Mushrooms and Truffes

A french small mushrooms business. News In this area, not to the German border, Vincent’s brother, Francis has been growing Oyster mushrooms since 1987, Pleurotes ostreatus and Shiitake – lentinus edodes. We are also selling white and brown button mushrooms, coming from Burgaentzlen in Colmar. Every week, there are about 400 kg, which are sold on Strasbourg open air markets. La Forestiere du Champignon is providing us wild mushrooms and blueberries coming from Vosges mountains. We get morels during 3 weeks only between 15 of April and 15 of May. Calocybe

Geology and the Great War - The geology of the Western Front, from Flanders to the Vosges

The western front was completely located in the Paris Basin, from the flatlands of Flanders to the Vosges Mountains. It was thus natural for the Association of the Geologists of the Basin of Paris (AGBP) to make its contribution to the remembrance of the Centenary of the Great War, with the realization of a synthesis of the present state of knowledge on the role played by the geology in this conflict.This synthesis, begun in 2014, will lead to a publication at the end of 2017.It will rely on the numerous works which were carried out by geographers and geologists during the war and in the years which followed, and will integrate the new studies, in particular those currently carried out on environmental issues.The publication will deal with:- The main geological structures of the battlefield;- The various geological formations intersected by the front line and their influence on the main battles;- The major battles replaced in their geological context;- Thematic chapters on hydrology, underground quarries, mine warfare, ground trafficability, environmental consequences, mineral supplies, new technologies . . .

Discovery of Living Populations of a Purported Fossil Diatom:Aulacoseira scalarisfrom Two Lakes in the Vosges Mountains (France)

Resume Dans le cadre du Programme de Surveillance repondant a la Directive europeenne Cadre sur l'Eau, un suivi du phytoplancton des plans d'eau de plus de 50 hectares est realise dans le bassin Rhin-Meuse. C'est lors de ce suivi que la diatomee centrique Aulacoseira scalaris (Grunow in Van Heurck) Houk, Klee & Passauer a ete identifiee dans les lacs de Longemer en 2010 (Xonrupt-Longemer, France) et de Gerardmer en 2011 (Gerardmer, France). Sa presence a ete a nouveau detectee dans les echantillons preleves en 2014 sur ces deux lacs. Aulacoseira scalaris n'avait ete jusqu'a present trouvee que dans des echantillons fossiles a subfossiles des U.S.A. (Etat de l'Oregon, et Virginia City de l'Etat du Nevada) et de France (Lac de Gerardmer, Vosges, France). Cette espece ayant ete retrouvee vivante dans le phytoplancton de ces deux lacs des Vosges, elle ne doit plus etre consideree comme uniquement une diatomee fossile. Des informations sur son autecologie sont proposees grâce aux donnees physicochimiques des d...

Experimental assessment of the water quality influence on the phosphorus uptake of an invasive aquatic plant: biological responses throughout its phenological stage.

Understanding how an invasive plant can colonize a large range of environments is still a great challenge in freshwater ecology. For the first time, we assessed the relative importance of four factors on the phosphorus uptake and growth of an invasive macrophyte Elodea nuttallii (Planch.) St. John. This study provided data on its phenotypic plasticity, which is frequently suggested as an important mechanism but remains poorly investigated. The phosphorus uptake of two Elodea nuttallii subpopulations was experimentally studied under contrasting environmental conditions. Plants were sampled in the Rhine floodplain and in the Northern Vosges mountains, and then maintained in aquaria in hard (Rhine) or soft (Vosges) water. Under these conditions, we tested the influence of two trophic states (eutrophic state, 100 μg.l−1 P-PO4 3− and hypertrophic state, 300 μg.l−1 P-PO4 3−) on the P metabolism of plant subpopulations collected at three seasons (winter, spring and summer). Elodea nuttallii was able to absorb high levels of phosphorus through its shoots and enhance its phosphorus uptake, continually, after an increase of the resource availability (hypertrophic > eutrophic). The lowest efficiency in nutrient use was observed in winter, whereas the highest was recorded in spring, what revealed thus a storage strategy which can be beneficial to new shoots. This experiment provided evidence that generally, the water trophic state is the main factor governing P uptake, and the mineral status (softwater > hardwater) of the stream water is the second main factor. The phenological stage appeared to be a confounding factor to P level in water. Nonetheless, phenology played a role in P turnover in the plant. Finally, phenotypic plasticity allows both subpopulations to adapt to a changing environment.

Microstructural evidences for mineralogical inheritance in partially molten rocks: example from the Vosges Mts

Abstract During orogenic processes continental crust experiences significant partial melting. Repeated thermal pulses or fluctuation in fluid content can even cause multiple anatectic events that result in complex intrusion suits. In the Vosges mountains, France, two main generations of magmatic rocks are recorded. The first magmatic event occurred at ca. 340 Ma, and is represented by extensive K-Mg granitoids magmatism. The second magmatic event occurred at ca. 325 Ma and produced large quantity of felsic anatectic melts which further pervasively intruded and compositionally and texturally reworked previously formed granitoids. Detailed field and microstructural observations revealed continuous transitions from porphyritic granite with large euhedral Kfs and Pl phenocrysts (Type I granite) via intermediate granite (Type II) to fine-grained apparently isotropic granite (Type III) dominated by the neo-crystallized melt. The Type I granite preserves the original magmatic assemblage and has only incipient amount of the newly crystallized melt. The new melt-crystallized material forms narrow, fine-grained pathways along grain boundaries or cuts across pre-existing magmatic grains and forms an interlinked network. With increasing amount of the newly crystallized material the original magmatic grains are resorbed and show highly corroded shapes. The early formed feldspars grains have strong compositional zoning, with oscillatory zoned cores reflecting range of original magmatic compositions and rims showing later melt overgrowths. Original magmatic feldspars have different composition from the new phases crystallizing in the partially molten granite. We interpret the fine-grained microscopic corridors as melt pathways that were exploited by the new magma. We suggest that this melt pervasively migrated through the older granitoids resulting in mixture of inherited “xenocrysts” and of new melt-derived crystals. The interaction between the new melt and previously crystallized granitoids results in variety of granite textures and fabrics. These reflect different degrees of equilibration between the bulk rock and the passing melt. Finally, Type III granite carries mixed isotopic signature intermediate between the type I granite and the surrounding metasediments and granulites, suggesting mixing of the original granite with new later magma with source in these rocks.

High‐resolution observations of precipitation from cumulonimbus clouds

ABSTRACTMaking high‐resolution observations of heavy rainfall from cumulonimbus clouds involves choosing a good location where convection occurs frequently and with some degree of predictability so that aircraft do not have to chase clouds, and radars and other ground‐based instruments can be optimally placed. It also requires significant resources, international collaboration and a good deal of serendipity. This paper describes several observational campaigns that were designed to understand relatively small‐scale convective clouds that produce heavy precipitation, and presents results that have been found over the years. It complements the companion papers in this special issue by giving an observational perspective. It is by no means comprehensive and is limited to cumulonimbus clouds. The Convective Storm Initiation Project (CSIP) was designed to understand the phenomena responsible for the initiation of convection in the maritime environment of southern England. There was a similar objective in the Convective Orographically‐induced Precipitation Study (COPS), but for the complex terrain of the Black Forest mountains, Germany, and the Vosges Mountains, France. The recent Convective Precipitation Experiment (COPE) was designed to understand the entire life cycle of convective clouds that formed along sea‐breeze convergence lines in the southwestern peninsula of England. Its particular focus was on the dynamics and microphysics of the convective clouds. Examples of observations from these and other field campaigns designed to study the initiation of convection, cumulonimbus clouds and convective precipitation are presented, with a view to demonstrating how they contribute to a physical understanding of the phenomena and the processes involved.

La prise en compte de la mémoire combattante à travers la muséographie

The Vosges mountain range is a region rich in history with an extraordinary memorial diversity. Between 1870 and 1945, there were three major conflicts, first between France and Germany, which then spread to all the other nations. This conflict would generate specificities that would transform these mountains into exceptional stages for European history in general and French history in particular. Indeed, the French-German war of 1870-1871 resulted in a border dividing the range in two along its north-south axis, transforming Alsace-Moselle into a German province. From that moment, the partitioning of the region, the border passes, and the monumentalisations imbued with revengeful nationalism would rhythm the entire range while a number of Optants” (residents of Lorraine who left the German province to maintain their French nationality) would modify the social and economic structure of a Lorraine that was profoundly affected territorially

Chemical and U–Sr isotopic variations in stream and source waters of the Strengbach watershed (Vosges mountains, France)

Abstract. This is the first comprehensive study dealing with major and trace element data as well as 87Sr/86Sr isotope and (234U/238U) activity ratios (AR) determined on the totality of springs and brooks of the Strengbach catchment. It shows that the small and more or less monolithic catchment drains different sources and streamlets with very different isotopic and geochemical signatures. Different parameters control the diversity of the source characteristics. Of importance is especially the hydrothermal overprint of the granitic bedrock, which was stronger for the granite from the northern slope; also significant are the different meteoric alteration processes of the bedrock causing the formation of 0.5 to 9 m thick saprolite and above the formation of an up to 1m thick soil system. These processes mainly account for springs and brooks from the northern slope having higher Ca / Na, Mg / Na, and Sr / Na ratios, but lower 87Sr/86Sr isotopic ratios than those from the southern slope. The chemical compositions of the source waters in the Strengbach catchment are only to a small extent the result of alteration of primary bedrock minerals, and rather reflect dissolution/precipitation processes of secondary mineral phases like clay minerals. The (234U/238U) AR, however, are decoupled from the 87Sr/86Sr isotope system, and reflect to some extent the level of altitude of the source and, thus, the degree of alteration of the bedrock. The sources emerging at high altitudes have circulated through already weathered materials (saprolite and fractured bedrock depleted in 234U), implying (234U/238U) AR below 1, which is uncommon for surface waters. Preferential flow paths along constant fractures in the bedrocks might explain the – over time – homogeneous U AR of the different spring waters. However, the geochemical and isotopic variations of stream waters at the outlet of the catchment are controlled by variable contributions of different springs, depending on the hydrological conditions. It appears that the (234U/238U) AR are a very appropriate, important tracer for studying and deciphering the contribution of the different source fluxes at the catchment scale, because this unique geochemical parameter is different for each individual spring and at the same time remains unchanged for each of the springs with changing discharge and fluctuating hydrological conditions. This study further highlights the important impact of different and independent water pathways on fractured granite controlling the different geochemical and isotopic signatures of the waters. Despite the fact that soils and vegetation cover have a great influence on the water cycle balance (evapotranspiration, drainage, runoff), the chemical compositions of waters are strongly modified by processes occurring in deep saprolite and bedrock rather than in soils along the specific water pathways.

An Observational and Modeling Study of the Processes Leading to Deep, Moist Convection in Complex Terrain

Abstract A case study of orographic convection initiation (CI) that occurred along the eastern slopes of the Vosges Mountains in France on 6 August 2007 during the Convective and Orographically-Induced Precipitation Study (COPS) is presented. Global positioning system (GPS) receivers and two Doppler on Wheels (DOW) mobile radars sampled the preconvective and storm environments and were respectively used to retrieve three-dimensional tomographic water vapor and wind fields. These retrieved data were supplemented with temperature, moisture, and winds from radiosondes from a site in the eastern Rhine Valley. High-resolution numerical simulations with the Weather Research and Forecasting (WRF) Model were used to further investigate the physical processes leading to convective precipitation. This unique, time-varying combination of derived water vapor and winds from observations illustrated an increase in low-level moisture and convergence between upslope easterlies and downslope westerlies along the eastern slope of the Vosges Mountains. Uplift associated with these shallow, colliding boundary layer flows eventually led to the initiation of moist convection. WRF reproduced many features of the observed complicated flow, such as cyclonic (anticyclonic) flow around the southern (northern) end of the Vosges Mountains and the east-side convergent flow below the ridgeline. The WRF simulations also illustrated spatial and temporal variability in buoyancy and the removal of the lids prior to convective development. The timing and location of CI from the WRF simulations was surprisingly close to that observed.

Geochemical and isotopic (U, Sr) tracing of water pathways in the granitic Ringelbach catchment (Vosges Mountains, France)

Major element concentrations and U and Sr isotope ratios were determined in waters collected from the main springs located in the small (0.36km2) Ringelbach catchment (Vosges, France), which has a basement consisting of Hercynian granite capped in its upper part by a residual cover of Triassic sandstones. The spring waters were sampled from 2001 to 2004 during highly contrasting hydrological conditions and monthly over two hydrological years October 2004–September 2006. Deep-water samples were also collected from three boreholes (two drilled down to a 150m depth and one down to a depth of 70m) and analyzed.The data indicate systematic geochemical differences between the waters from sandstone and granite and important spatial variations in the chemical and isotopic compositions (Sr and U) between the spring waters on granitic lithology. For the granitic spring waters, the alkalinity, the cationic concentrations and the pH values increase with decreasing spring elevation. The (234U/238U) activity ratios of the granitic spring waters also increase with decreasing spring elevation, from approximately 1 in the upslope springs to 1.3 in the downslope springs. Waters of each spring have significant temporal variations in the elemental concentrations and elemental ratios but much less variations in their Sr isotopic ratios and U activity ratios. These spatial and temporal geochemical variations are unrelated to both the mixing scenarios between weathering and rainwater end-members and between granitic and sandstone weathering fluxes. Moreover, the comparison of the geochemical and isotopic compositions of Sr and U of the granitic spring waters with those of deep waters collected from boreholes demonstrates that the geochemical variations in the granitic spring waters cannot be explained by mixing between the surface water and these deep groundwaters. The spring waters are supplied by subsurface waters flowing through water paths disconnected from those of the borehole waters. Furthermore, the geochemical and Sr isotopic characteristics of the granitic spring waters suggest that the different granitic springs are most likely supplied by waters with relatively independent water pathways that are controlled by the geometry of the fracture network structure in the Ringelbach regolith. The increase in the alkalinity, the major element (Na+, Ca2+, Mg2+) concentrations and the U activity ratios of the granitic spring waters with decreasing spring elevation indicate that the main parameter that must be considered to explain the geochemical characteristics of these waters is the length of the water pathway within the bedrock, which controls the duration of the water–rock interactions. Based on this interpretation, the (234U/238U) activity ratios in the spring waters were modeled using a simple 1D reactive transport model that considers dissolution, precipitation and alpha recoil. By estimating the alpha recoil factor and the length of the water path for each spring, both the dissolution rate of the bedrock and the water residence time within the slope can be estimated.

Impact of Bacterial Activity on Sr and Ca Isotopic Compositions (87Sr/86Sr and δ44/40Ca) in Soil Solutions (the StrengbachCZO)

This study deals with soil solutions originating from the spruce parcel of the Strengbach catchment (Vosges mountains, Northeastern France). Samples were collected during winter, spring and summer 2010. Their chemical and isotopic (87Sr/86Sr and δ44/40Ca)compositions allowed to identify micro-organism activity and bio-weathering of apatite in the soil solutions from uppermost (0-10cm depth) soil horizons. Indeed, in presence of bacteria, any Ca isotopic fractionation due to vegetation uptake is ruled out and δ44/40Ca values reflect the signature of apatite. Thus, bacteria facilitate the Ca uptake from soil. This study highlights the potential of Ca isotopes to identify bacteria activity in soils.