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Tunnel drilling provides a unique opportunity to sample and study deep groundwaters that are otherwise difficult to access. Understanding deep groundwater flow is of primary importance in assessing the possible impacts of tunnelling on hydrogeological systems. During this study, water was sampled for noble-gas analysis from tunnel inflows in the AlpTransit Ceneri Base Tunnel (Canton Ticino, southern Switzerland), which passes through an area mainly characterized by metamorphic rocks (gneiss). Furthermore, water was sampled from springs located in the same geological environment. Based on the measurement of noble-gas concentrations and isotope ratios, tritium concentrations, the stable isotope composition of hydrogen ( δ 2 H) and oxygen ( δ 18 O), and the concentrations of major ions in the water, a conceptual hydrogeological model was established for this case study that allowed the most probable origin of the groundwaters sampled at different locations to be determined. The measured abundances of 3 He, 4 He, and 20 Ne allow the geochemical characterization of old groundwaters strongly enriched in terrigenic helium of crustal origin and the identification of mixing with water that circulates preferentially through cataclastic structures. Noble-gas concentrations and isotope ratios as well as tritium are useful proxies for the characterization of faults that may be critical for tunnel drilling because of their active hydrogeological role and their influence on the mechanics of the rocks.

The application of organic amendments on soils poor in organic matter (OM) can improve long-term soil fertility, but may also enhance the mineralization of native soil organic matter. Three organic amendments, compost, sewage sludge and horse manure, used by urban market gardeners in Dakar, Senegal were analyzed for their OM maturity. Their fate was evaluated in a 45-d agronomic trial in a sandy Arenosol with lettuce. In each case, water-extractable organic matter (WEOM) and humic-like substances (HLS) were isolated from raw amendments and amended soils, and characterized using ultraviolet-visible (UV/Vis) spectroscopy. Results highlighted the general more aromatic character of HLS and WEOM fractions extracted from compost compared to the other two amendments. When applied to soils, however, these differences were not clearly observed. The aromaticity and humification degree of the labile fraction (WEOM) increased with depth in the first 30 cm for all amendments. This indicated the high lixiviation rates that fresh OM underwent in the studied sandy soil. Finally, a statistical analysis of the results was able to discriminate between surface and deeper horizons and between amended- and non-amended soil samples. Spectroscopic indices showed indeed strong increase/decrease with depth linked with the mineralization/humification processes that the fresh OM from amendments underwent during the 45 d of the agronomic trial. This study highlights the potential of spectroscopic techniques to study agricultural amendment organic matter fractions and their fate in soils.

In an active tailings impoundment, we studied the evolution of freshly deposited tailings from alkaline, unoxidized to acidic, oxidized tailings tracing changes in pore water quality, mineralogy, and element pathways. The tailings originate from the giant porphyry copper deposit Chuquicamata (Chile), and were deposited in different basins with varying times of surface exposure (0 to five years) to the hyper-arid climate in the Atacama desert. Fresh alkaline tailings (pH 9.1) had high concentrations of dissolved Na (1773 mg/L), Ca (556 mg/L), SO 4 (2496 mg/L) and Cl (1678 mg/L) due to dissolution of primary gypsum, and high dissolved element concentrations in the flotation process water due to recycling of water from the tailings impoundment. High As and Mo concentrations resulted from desorption processes during the flotation, with minor contributions from As-rich river water and recycled tailings water. After draining of free water in freshly deposited tailings, evaporation-driven capillary rise was the dominant water transport in the vadose zone. In younger tailings (up to three years), the pH decreased due to sulfide oxidation to circumneutral values (6.4–8.6). The capillary fringe reached 1 m depth, where ongoing evaporation enriched Na (up to 5483 mg/L), K (742 mg/L), and Cl (6892 mg/L). In the vadose zone above 1 m, the high daily temperature amplitude resulted in condensation of pore water in the uppermost 80 cm of sedimented tailings. Subsequent capillary rise depleted uppermost tailings in soluble phases and increase superficial salt precipitation (halite, gypsum and Na–K–Ca–Mg sulfates). After four years, a 13 cm thick oxidation zone with acidic pH (4.7) evolved. After five years, a well-defined oxidation zone (28 cm thickness) with low pH (3.8) and high mobility of heavy metals was found (e.g., 247 mg/L Fe, 177 mg/L Cu, 61.8 mg/L Zn). This mobility allowed transport and enrichment in the efflorescent salt crust (e.g., as Cu sulfates devilline, krohnkite and Cu-chlorides eriochalcite and atacamite), with SO 4 dominantly from sulfide oxidation (− 1.0 to 5.9‰ δ 34 S, − 1.0 to 4.4‰ δ 18 O sulfates ). Stable isotope data suggest that capillary rise from the water table reached the surface, most probably due to the reduction of pore size by precipitating secondary minerals, decreased water loss by clogging of pores and heat isolation by the efflorescent salt crust. The cycles of surface exposure and new tailings deposition in the last decades resulted in buried former oxidation zones, which showed lesser K and Cu concentrations in Fe oxides than recent oxidized tailings, most probably due to the transformation of jarosite and schwertmannite to Fe(3 +) oxyhydroxides and dissolution of Cu sulfates. Pore water in the saturated deep tailings was highly dynamic and displayed influences of local groundwater, and mixing with acid rock drainage (ARD) and fresh tailings water, both infiltrating from the surface. At the tailings dam, seepage water varied in time between neutralized ARD and fresh tailings water with groundwater influence, due to the periodic shift of the deposition zone and the resulting shallow groundwater changes. Adjacent efflorescent salts include typical minerals found in the secondary porphyry copper deposits in northern Chile (e.g., atacamite), displaying the similarity between geochemical processes in weathered tailings impoundments and secondary enrichment zones of ore bodies, like Exotica from the Chuquicamata mine.

Two parcels of the Lavaux vineyard area, western Switzerland, were studied to assess to which extent the widely used herbicide, glyphosate, and its metabolite aminomethylphosphonic acid (AMPA) were retained in the soil or exported to surface waters. They were equipped at their bottom with porous ceramic cups and runoff collectors, which allowed retrieving water samples for the growing seasons 2010 and 2011. The role of slope, soil properties and rainfall regime in their export was examined and the surface runoff/throughflows ratio was determined with a mass balance. Our results revealed elevated glyphosate and AMPA concentrations at 60 and 80 cm depth at parcel bottoms, suggesting their infiltration in the upper parts of the parcels and the presence of preferential flows in the studied parcels. Indeed, the succession of rainy days induced the gradual saturation of the soil porosity, leading to rapid infiltration through macropores, as well as surface runoff formation. Furthermore, the presence of more impervious weathered marls at 100 cm depth induced throughflows, the importance of which in the lateral transport of the herbicide molecules was determined by the slope steepness. Mobility of glyphosate and AMPA into the unsaturated zone was thus likely driven by precipitation regime and soil characteristics, such as slope, porosity structure and layer permeability discrepancy. Important rainfall events (>10 mm/day) were clearly exporting molecules from the soil top layer, as indicated by important concentrations in runoff samples. The mass balance showed that total loss (10–20%) mainly occurred through surface runoff (96%) and, to a minor extent, by throughflows in soils (4%), with subsequent exfiltration to surface waters.

The Lepontine dome represents a unique region in the arc of the Central and Western Alps, where complex fold structures of upper amphibolite facies grade of the deepest stage of the orogenic belt are exposed in a tectonic half-window. The NW-verging Mont Blanc, Aar und Gotthard basement folds and the Lower Penninic gneiss nappes of the Central Alps were formed by ductile detachment of the upper European crust during its Late Eocene–Early Oligocene SE-directed underthrust below the upper Penninic and Austroalpine thrusts and the Adriatic plate. Four underthrust zones are distinguished in the NW-verging stack of Alpine fold nappes and thrusts: the Canavese, Piemont, Valais and Adula zones. Up to three schistosities S1–S3, folds F1–F3 and a stretching lineation XI with top-to-NW shear indicators were developed in the F1–F3 fold nappes. Spectacular F4 transverse folds, the SW-verging Verzasca, Maggia, Ziccher, Alpe Bosa and Wandfluhhorn anticlines and synclines overprint the Alpine nappe stack. Their formation under amphibolite facies grade was related to late ductile folding of the southern nappe roots during dextral displacement of the Adriatic indenter. The transverse folding F4 was followed since 30 Ma by the pull-apart exhumation and erosion of the Lepontine dome. This occurred coevally with the formation of the dextral ductile Simplon shear zone, the S-verging backfolding F5 and the formation of the southern steep belt. Exhumation continued after 18 Ma with movement on the brittle Rhone-Simplon detachment, accompanied by the N-, NW- and W-directed Helvetic and Dauphiné thrusts. The dextral shear is dated by the 29–25 Ma crustal-derived aplite and pegmatite intrusions in the southern steep belt. The cooling by uplift and erosion of the Tertiary migmatites of the Bellinzona region occurred between 22 and 18 Ma followed by the exhumation of the Toce dome on the brittle Rhone–Simplon fault since 18 Ma.

The Dakar area, situated in the tropical, semiarid climate of the Sahel zone, has been subject to important urban development during the last 40 years due to migration from rural areas in the 1970s, following several droughts and population growth. This has led to an increase of water consumption and the related risks for man and ecosystems: pollution of aquifers (eutrophication, salt, pesticides), changes in agricultural production (increased salt content, endangering soil fertility), and frequent floods in the lowlands occupied by informal settlements. During the last 10 years various geochemical studies, including chemical analyses of soils and water, as well as isotopic and microbiological methods have allowed to obtain a detailed picture of the physical and chemical processes occurring in the local aquifers and soils, as a result of anthropogenic influences. Collaboration with town planners, local NGOs, and governmental agencies has allowed for an overall view of the origin and impacts of the ongoing complex processes and related risks. In view of the upcoming scarcity of water and rapidly progressing urbanization, continuing this interdisciplinary approach will hopefully allow for risk reduction and more sustainable development of the area.

Between the cities of Domodossola and Locarno, the complex “Centovalli Line” tectonic zone of the Central Alps outlines deformation phases over a long period of time (probably starting ~ 30 Ma ago) and under variable P–T conditions. The last deformation phases developed gouge-bearing faults with a general E–W trend that crosscuts the roots of the Alpine Canavese zone and the Finero ultramafic body. Kinematic indicators show that the general motion was mainly dextral associated with back thrusting towards the S. The On the basis of the K–Ar ages and with a thermal gradient of 25–30 °C/km, the studied fault zones were located at a depth of 4–7 km. If they were active until now as observed in field, the exhumation was approximately 2.5–3.0 km for the last 12 Ma with a mean velocity of 0.4 mm/y. Comparison with available models on the recent Alpine evolution shows that the tectonic activity in the area relates to a continuum of the back-thrusting movements of the Canavese Line, and/or to several late-extensional phases of the Rhone–Simplon Line. The Centovalli–Val Vigezzo zone therefore represents a major tectonic zone of the Central–Western Alps resulting from different interacting tectonic events.

The sandstone-hosted Beverley uranium deposit is located in terrestrial sediments in the Lake Frome basin in the North Flinders Ranges, South Australia. The deposit is 13 km from the U-rich Mesoproterozoic basement of the Mount Painter inlier, which is being uplifted 100 to 200 m above the basin by neotectonic activity that probably initiated in the early Pliocene. The mineralization was deposited mainly in organic matter-poor Miocene lacustrine sands and partly in the underlying reductive strata comprising organic matter-rich clays and silts. The bulk of the mineralization consists of coffinite and/or uraninite nodules, growing around Co-rich pyrite with an S isotope composition ( δ 34 S = 1.0 ± 0.3‰), suggestive of an early diagenetic lacustrine origin. In contrast, authigenic sulfides in the bulk of the sediments have a negative S isotope signature ( δ 34 S ranges from −26.2 to −35.5‰), indicative of an origin via bacterially mediated sulfate reduction. Minor amounts of Zn-bearing native copper and native lead also support the presence of specific, reducing microenvironments in the ore zone. Small amounts of carnotite are associated with the coffinite ore and also occur beneath a paleosoil horizon overlying the uranium deposit. Provenance studies suggest that the host Miocene sediments were derived from the reworking of Early Cretaceous glacial or glaciolacustrine sediments ultimately derived from Paleozoic terranes in eastern Australia. In contrast, the overlying Pliocene strata were in part derived from the Mesoproterozoic basement inlier. Mass-balance and geochemical data confirm that granites of the Mount Painter domain were the ultimate source of U and REE at Beverley. U-Pb dating of coffinite and carnotite suggest that the U mineralization is Pliocene (6.7-3.4 Ma). The suitability of the Beverley deposit for efficient mining via in situ leaching, and hence its economic value, are determined by the nature of the hosting sand unit, which provides the permeability and low reactivity required for high fluid flow and low chemical consumption. These favorable sedimentologic and geometrical features result from a complex conjunction of factors, including deposition in lacustrine shore environment, reworking of angular sands of glacial origin, deep Pliocene weathering, and proximity to an active fault exposing extremely U rich rocks.

Human activity results in the production of a wide range of pollutants that can enter the water cycle through stormwater or wastewater. Among others, heavy metals are still detected in high concentrations around urban areas and their impact on aquatic organisms is of major concern. In this study, we propose to use a substance flow analysis as a tool for heavy metals management in urban areas. We illustrate the approach with the case of copper in Lausanne, Switzerland. The results show that around 1,500 kg of copper enter the aquatic compartment yearly. This amount contributes to sediment enrichment, which may pose a long-term risk for benthic organisms. The major sources of copper in receiving surface water are roofs and catenaries of trolleybuses. They represent 75% of the total input of copper into the urban water system. Actions to reduce copper pollution should therefore focus on these sources. Substance flow analysis also highlights that copper enters surface water mainly during rain events, i.e., without passing through any treatment procedure. A reduction in pollution could also be achieved by improving stormwater management. In conclusion, the study showed that substance flow analysis is a very effective tool for sustainable urban water management.

Artificial radionuclides ( 137 Cs, 90 Sr, Pu, and 241 Am) are present in soils because of Nuclear Weapon Tests and accidents in nuclear facilities. Their distribution in soil depth varies according to soil characteristics, their own chemical properties, and their deposition history. For this project, we studied the atmospheric deposition of 137 Cs, 90 Sr, Pu, 241 Am, 210 Pb, and stable Pb. We compared the distribution of these elements in soil profiles from different soil types from an alpine Valley (Val Piora, Switzerland) with the distribution of selected major and trace elements in the same soils. Our goals were to explain the distribution of the radioisotopes as a function of soil parameters and to identify stable elements with analogous behaviors. We found that Pu and 241 Am are relatively immobile and accumulate in the topsoil. In all soils, 90 Sr is more mobile and shows some accumulations at depth into Fe–Al rich horizons. This behavior is also observed for Cu and Zn, indicating that these elements may be used as chemical analogues for the migration of 90 Sr into the soil.

Rare earth elements (REE) and stable isotope compositions (?13C and ?18O) of shark teeth and phosphatic coprolites were analyzed from the Lower Maastrichtian layers of the El Haria Formation and two sequences of the Paleocene–Eocene (P/E) Chouabine Formation in the Gafsa Basin (south western of Tunisia) in order to trace the sedimentological, climatic and oceanographic conditions. The REE chemistry and their distribution in the two archives are the same for each of the studied layers indicating that the coprolites and shark teeth experienced the same early diagenetic environments. However major differences occur between the Maastrichtian and the P/E reflecting changes in the depositional conditions. The Early Maastrichtian burial environment tended to be more anoxic with REE derived from reduced FeO. While in the P/E the REE patterns mimic the modern oxic–suboxic seawater, the REE source from remineralisation of organic coating could have more significance. The oxygen isotope compositions of the structural phosphates (?18OPO4) indicate a stable and warm climate during both studied time intervals. A small offset ( 0.4‰) in the ?18O value between the coprolites and shark teeth show minor thermal gradient between bottom and surface water. The pronounced negative shift of 3–4‰ in ?13C values recorded in the upper part of the Chouabine Formation was ascribed to the Paleocene–Eocene boundary. At the same time the lack of negative change in the ?18O is explained by the semi-closed situation of the Gafsa Basin, which situation also played an important role in the evolution of the organic matters in the sediment resulting in the exceptional low ?13C values.

Prevention of acid mine drainage (AMD) in sulfide-containing tailings requires the identification of the geochemical processes and element pathways in the early stages of tailing deposition. However, analyses of recently deposited tailings in active tailings impoundments are scarce because mineralogical changes occur near the detection limits of many assays. This study shows that a detailed geochemical study which includes stable isotopes of water (δ2H, δ18O), dissolved sulfates (δ34S, δ18O) and hydrochemical parameter (pH, Eh, DOC, major and trace elements) from tailings samples taken at different depths in rainy and dry seasons allows the understanding of weathering (oxidation, dissolution, sorption, and desorption), water and element pathways, and mixing processes in active tailings impoundments. Fresh alkaline tailings (pH 9.2–10.2) from the Cu–Mo porphyry deposit in El Teniente, Chile had low carbonate (0.8–1.1 wt.% CaCO3 equivalent) and sulfide concentrations (0.8–1.3 wt.%, mainly as pyrite). In the alkaline tailings water, Mo and Cu (up to 3.9 mg/L Mo and 0.016 mg/L Cu) were mobile as MoO42− and Cu(OH)20. During the flotation, tailings water reached equilibrium with gypsum (up to 738 mg/L Ca and 1765 mg/L SO4). The δ34S vs. δ18O covariations of dissolved sulfate (2.3 to 4.5‰ δ34S and 4.1 to 6.0 ‰ δ18O) revealed the sulfate sources: the dissolution of primary sulfates (12.0 to 13.2‰ δ34S, 7.4 to 10.9‰ δ18O) and oxidation of primary sulfides (− 6.7 to 1.7‰ δ34S). Sedimented tailings in the tailings impoundment can be divided into three layers with different water sources, element pathways, and geochemical processes. The deeper sediments (> 1 m depth) were infiltrated by catchment water, which partly replaced the original tailings water, especially during the winter season. This may have resulted in the change from alkaline to near-neutral pH and towards lower concentrations of most dissolved elements. The neutral pH and high DOC (up to 99.4 mg/L C) of the catchment water mobilized Cu (up to 0.25 mg/L) due to formation of organic Cu complexes; and Zn (up to 130 mg/L) due to dissolution of Zn oxides and desorption). At 1 m depth, tailings pore water obtained during the winter season was chemically and isotopically similar to fresh tailings water (pH 9.8–10.6, 26.7–35.5 mg/L Cl, 2.3–6.0 mg/L Mo). During the summer, a vadose zone evolved locally and temporarily up to 1.2 m depth, resulting in a higher concentration of dissolved solids in the pore water due to evaporation. During periodical new deposition of fresh tailings, the geochemistry of the surface layer was geochemically similar to fresh tailings. In periods without deposition, sulfide oxidation was suggested by decreasing pH (7.7–9.5), enrichment of MoO42− and SO42−, and changes in the isotopic composition of dissolved sulfates. Further enrichment for Na, K, Cl, SO4, Mg, Cu, and Mo (up to 23.8 mg/L Mo) resulted from capillary transport towards the surface followed by evaporation and the precipitation of highly soluble efflorescent salts (e.g., mirabilite, syngenite) at the tailing surface during summer.

The mine wastes and their environmental impact described in this paper are related to a skarn-type ore deposit, located in the Variscan crystalline basement of the Aiguilles Rouges Massive, Western Switzerland. The main minerals of the deposit are arsenopyrite, lollingite, hematite, scheelite, magnetite, pyroxene, amphibole and dolomite. The ore has been mined for arsenic and gold between 1900 and 1928, producing about 700 t As and 55 kg Au, and leaving mine dumps of several hundred m 3 , situated on a relatively steep hill above the small Lake Ottans, at an altitude of 2200 m. This work was undertaken to determine the extent of the As-contamination, its environmental impact and to identify actual geochemical processes. Dump materials contain As and sulfur in the 10% range, contaminated soils contain between 50 mg/kg and several % As. Mine and dump percolating waters are weakly mineralized of the Ca–Mg–HCO 3 –SO 4 -type and have conductivities between 20 and 170 μS/cm, pH values around 8, and As contents varying from 60 to 4000 μg/l. Waters below the dump zone are of the same type and have slightly lower As-contents: in Lake Ottans, 200 m below the mine area, As is still between 100 and 160 μg/l. Our results indicate that: (1) the contaminated area is limited to about 500 m in radius (1.2 km 2 ) and that its environmental impact is rather limited, except for grazing cattle, (2) below the mine, the As decreases more rapidly in the soils than in the waters, (3) the distribution of the As seems to be determined by predominant alkaline pH in the surface and ground waters and by the distribution of the secondary solid phases (Fe-oxy-hydroxides, clays, carbonate minerals, especially in the lower part). Transport by gravity creep or as suspended particles in water seems to be of secondary importance.

The distribution and diversity of acidophilic bacteria of a tailings impoundment at the La Andina copper mine, Chile, was examined. The tailings have low sulfide (1.7% pyrite equivalent) and carbonate (1.4% calcite equivalent) contents and are stratified into three distinct zones: a surface (0-70-80 cm) 'oxidation zone' characterized by low-pH (2.5-4), a 'neutralization zone' (70-80 to 300-400 cm) and an unaltered 'primary zone' below 400 cm. A combined cultivation-dependent and biomolecular approach (terminal restriction enzyme fragment length polymorphism and 16S rRNA clone library analysis) was used to characterize the indigenous prokaryotic communities in the mine tailings. Total cell counts showed that the microbial biomass was greatest in the top 125 cm of the tailings. The largest numbers of bacteria (10(9) g(-1) dry weight of tailings) were found at the oxidation front (the junction between the oxidation and neutralization zones), where sulfide minerals and oxygen were both present. The dominant iron-/sulfur-oxidizing bacteria identified at the oxidation front included bacteria of the genus Leptospirillum (detected by molecular methods), and Gram-positive iron-oxidizing acidophiles related to Sulfobacillus (identified both by molecular and cultivation methods). Acidithiobacillus ferrooxidans was also detected, albeit in relatively small numbers. Heterotrophic acidophiles related to Acidobacterium capsulatum were found by molecular methods, while another Acidobacterium-like bacterium and an Acidiphilium sp. were isolated from oxidation zone samples. A conceptual model was developed, based on microbiological and geochemical data derived from the tailings, to account for the biogeochemical evolution of the Piuquenes tailings impoundment.

Reference ECOS-ARTICLE-2007-065View record in Web of Science Record created on 2007-11-28, modified on 2016-08-08

In recent years, elevated arsenic concentrations have been found in waters and soils of many countries, often resulting in a health threat for the local population. Switzerland is not an exception and this paper deals with the release and subsequent fate of arsenic in a 200-km2 mountainous watershed, characterized by crystalline silicate rocks (gneisses, schists, amphibolites) that contain abundant As-bearing sulfide ore deposits, some of which have been mined for iron and gold in the past. Using analytical methods common for mineralogical, ground water and soil studies (XRD, XRF, XAS-XANES and -EXAFS, electron microprobe, extraction, ICP, AAS with hydride generator, ion chromatography), seven different field situations and related dispersion processes of natural arsenic have been studied: (1) release by rock weathering; (2) transport and deposition by water and ice; (3) release of As to the ground and surface water due to increasing pH; (4) accumulation in humic soil horizons; (5) remobilization by reduction in water-saturated soils and stagnant ground waters; (6) remobilization by using P-rich fertilizers or dung and (7) oxidation, precipitation and dilution in surface waters. Comparison of the results with experimental adsorption studies and speciation diagrams from the literature allows us to reconstruct and identify the typical behavior of arsenic in a natural environment under temperate climatic conditions. The main parameters identified are: (a) once liberated from the primary minerals, sorption processes on Fe-oxy-hydroxides dominate over Al-phases, such as Al-hydroxides or clay minerals and limit the As concentrations in the spring and well waters between 20 and 300 μg/l. (b) Precipitation as secondary minerals is limited to the weathering domain, where the As concentrations are still high and not yet too diluted by rain and soils waters. (c) Although neutral and alkaline pH conditions clearly increase the mobility of As, the main factor to mobilize As is a low redox potential (Eh close or below 0 mV), which favors the dissolution of the Fe-oxy-hydroxides on which the As is sorbed. (d) X-ray absorption spectroscopy (XAS) of As in water-logged humic forest soils indicates that the reduction to As III only occurs at the solid–water interface and that the solid contains As as As V. (e) A and Bh horizons of humic cambisols can effectively capture As when As-rich waters flow through them. Complex spatial and temporal variation of the various parameters in a watershed results in repeated mobilization and immobilization of As, which continuously transports As from the upper to the lower part of a watershed and ultimately to the ocean.

b ´ Abstract Anthropogenic emissions of metals from sources such as smelters are an international problem, but there is limited published information on emissions from Australian smelters. The objective of this study was to investigate the regional distribution of heavy metals in soils in the vicinity of the industrial complex of Port Kembla, NSW, Australia, which comprises a copper smelter, steelworks and associated industries. Soil samples (ns25) were collected at the depths of 0-5 and 5-20 cm, air dried and sieved to -2 mm. Aqua regia extractable amounts of As, Cr, Cu, Pb and Zn were analysed by inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma atomic emission spectrometry (ICP-AES). Outliers were identified from background levels by statistical methods. Mean background levels at a depth of 0-5 cm were estimated at 3.2 mgykg As, 12 mgykg Cr, 49 mgykg Cu, 20 mgykg Pb and 42 mgykg Zn. Outliers for elevated As and Cu values were mainly present within 4 km from the Port Kembla industrial complex, but high Pb at two sites and high Zn concentrations were found at six sites up to 23 km from Port Kembla. Chromium concentrations were not anomalous close to the industrial complex. There was no significant difference of metal concentrations at depths of 0-5 and 5-20 cm, except for Pb and Zn. Copper and As concentrations in the soils are probably related to the concentrations in the parent rock. From this investigation, the extent of the contamination emanating from the Port Kembla industrial complex is limited to 1-13 km, but most likely -4 km, depending on the element; the contamination at the greater distance may not originate from the industrial complex. 2003 Elsevier B.V. All rights reserved.

Regions under tropical rainforest cover, such as central Africa and Brazil are characterised by degradation and dismantling of old ferricrete structures. In southern Cameroon, these processes are relayed by present-day ferruginous accumulation soil facies, situated on the middle and the lower part of hill slopes. These facies become progressively harder towards the surface, containing from bottom to top, mainly kaolinite, kaolinite–goethite and Al-rich goethite–hematite, and are discontinuous to the relictic hematite-dominated ferricrete that exist in the upper part of the hill slope. These features were investigated in terms of geochemical differentiation of trace elements. It appears that, in contrast to the old ferricrete facies, the current ferruginous accumulations are enriched in transitional trace elements (V, Cr, Co, Y, Sc) and Pb, while alkali-earth elements are less differentiated. This recent chemical accumulation is controlled both by intense weathering of the granodiorite bedrock and by mobilisation of elements previously accumulated in the old ferricrete. The observed processes are clearly linked to the present-day humid climate with rising groundwater tables. They slowly replace the old ferricretes formed during Cretaceous time under more seasonal climatic conditions, representing an instructive case of continuos global change.

Present downslope iron accumulations were investigated in the rainforest zone in southern Cameroon. Six clay and Fe-hydroxide dominated patterns have been identified and occur on the lower part of hill slopes. They can be subdivided in three different sequences, related to gentle, moderate or steep slopes. They are discontinuous with respect to the dismantling zone of the old ferricrete cap formed at Cretaceous period. They show a gradual development from a soft Fe-crust (carapace) to a vesicular facies that will, with time, cover the whole landscape again. To cite this article: E. Temgoua et al., C. R. Geoscience 334 (2002) 537–543.

UV/Vis fluorescence spectroscopy was used to study the possible interactions of dissolved organic matter (DOM) with the herbicide glyphosate and copper-based fungicide used in vineyards. The study focused on the role of DOM in the transport of these micropollutants from parcels to surface waters (river, lake). Soil solution and river water samples were collected in the Lavaux vineyard area, western Switzerland. Their fluorescence excitation emission matrices (EEM) were decomposed using parallel factor (PARAFAC) analysis, and compared to their content in glyphosate and copper. PARAFAC analysis of EEM of both types of samples showed the contribution of protein-like and humic-like fluorophores. In soil water samples, complexes between fulvic-like and humic-like fluorophores of DOM, copper, and glyphosate were likely formed. In surface water, DOM-copper and glyphosate-copper interactions were observed, but not between glyphosate and DOM.

Many studies have been carried out to identify dissolved organic matter–trace metals interactions, as organic matter (OM) was demonstrated to be a governing parameter of metals speciation. Concerning arsenic (As), such OM–As studies are scarce and concluded that, when As binding occurred, it was probably through cationic bridges or, in some cases, directly. Yet, analytical proofs remained complex to obtain. In this work, As binding with Suwanee River Humic Acid (SRHA), as an example of dissolved organic matter, was studied, considering both As III and As V , at various pH and in absence/presence of Na and Ca. Dialysis, fluorescence measurements and PHREEQC modelling were performed to identify and characterize the mechanisms at work for the various performed experiments. It was observed that As III binding on SRHA occurred through direct SRHA–As III binding and that neither Na nor Ca presence modify this mechanism. As V appeared to be also bound by SRHA through direct interaction, but suffered from the competition of Na for the SRHA binding sites. Oppositely, in presence of Ca, the overall As V –SRHA binding was significantly enhanced, Ca acting as an efficient cationic bridge through the formation of an SRHA–Ca–As V ternary complex. All the obtained data were satisfactorily simulated using a unique set of binding parameters which can therefore be implemented in any speciation code to better address As behaviour in environmental conditions.

We investigated mercury (Hg) exposure of food web and humans in the region of Kedougou, Senegal, where Hg is used for gold amalgamation in artisanal small-scale gold mining (ASGM). For this purpose, total mercury (THg) concentration was determined in eight fish species and two shellfish species from Gambia River and in human hair from 111 volunteers of different age and sex, living in urban locations (Kedougou and Samekouta) or in ASGM areas (Tinkoto and Bantako). THg concentrations in fish samples range from 0.03 to 0.51 mg kg(-1) wet weight (ww) and 0.5 to 1.05 mg kg(-1) ww for shellfish. THg concentrations in fish are below the WHO guideline of 0.5 mg kg(-1) ww, whereas 100 % of shellfish are above this safety guideline. In the entire set of fish and shellfish samples, we documented a decrease of THg concentrations with increasing selenium to mercury (Se:Hg) ratio suggesting a protection of Se against Hg. However, local population consuming fish from the Gambia River in the two ASGM areas have higher THg concentrations (median = 1.45 and 1.5 mg kg(-1) at Bantako and Tinkoto) in hair than those from others localities (median = 0.42 and 0.32 mg kg(-1) at Kedougou town and Samekouta) who have diverse diets. At ASGM sites, about 30 % of the local population present Hg concentrations in hair exceeding 1 mg kg(-1), defined as the reference concentration of Hg in hair. We also evidence a higher exposure of women to Hg in the Tinkoto ASGM site due to the traditional distribution of daily tasks where women are more involved in the burning of amalgams. The discrepancy between the calculated moderate exposure through fish consumption and the high Hg concentrations measured in hair suggest that fish consumption is not the only source of Hg exposure and that further studies should focus on direct exposure to elemental Hg of population living at ASGM sites.

International audience; The coupling of analytical tools and modeling approaches allowed the identification of the key parameters controlling arsenic (As) dynamics in anoxic marine sediments. Eh, pH, dissolved/particulate As, Fe, Mn, S, P, and organic/inorganic C were determined in sedimentary porewaters and in the sediments itself at 3 geochemically contrasting stations and at different seasons, in the heavily contaminated, semi-closed Toulon bay (NW Mediterranean Sea). Elemental analysis and selective extractions allowed the identification of As distribution in the studied sediments. Organic matter (OM) quality was characterized by fluorescence measurements. A 1D steady-state modeling (PROFILE) was used to estimate depth reaction intervals and reaction rates by fitting the measured element profiles. Thermodynamic simulation (PHREEQC) was also performed to calculate the chemical speciation and simulate the dissolved/particulate As fractionation. This work demonstrated the consistency of the additive speciation/adsorption modeling to simulate As profiles in marine porewaters while considering the different sedimentary phases and the species that could potentially act as competitors (e.g. CO3 2-, PO4 3-, . . .). By taking into account the presence of OM and appropriately adjusting its reactivity toward As, the simulated dissolved As profiles consistently fitted the measured one. This As-OM reactivity is related to the organic matter quality, determined by fluorescence measurements.In all samples, As dynamics in the subsurface sediments was shown to be strongly linked to the iron cycling, especially to amorphous iron oxyhydroxide, through diagenesis reactions. The Fe/As ratio involved in the diagenesis processes (determined both experimentally and from the PHREEQC simulation of the dissolved As profiles without organic matter interaction) was close to ~210. Higher ratio was predicted by the simulation when considering the As-organic matter interaction. A similar observation was found for other mineral phases in sulfidic sediments (sulfide, clays . . .). The decreased affinity of As for inorganic minerals could be due to a competition between organic/inorganic phases or to a ternary arsenic-OM-inorganic phase association, as recently suggested in the literature. Trials provided OM-As stability constant values in these samples, ranging (in log10) from 2 to 3.2 for particulate OM and from 2 to 4.7 for dissolved OM. Therefore, organic matter was clearly shown to play a role in As dynamics in sediments or porewater (and thus potentially in other natural samples), even in the presence of inorganic phases. OM, thus, should be added in databases and taken into account in future simulations. \textcopyright 2014 Elsevier B.V.

International audience; Laguna Chicho'j (Lake Chicho' j) is the only deep permanent lake in the central highlands of Guatemala. The lake is located in the boundary zone between the North American and Caribbean plates. The lake has been struck by devastating earthquakes and tropical cyclones in historical times. We investigated the imprint of twentieth century extreme events on the sedimentary record of this tropical lake using a bathymetric survey of the lake, coring the lake floor, and providing a chronology of sediment accumulation. The lake occupies a series of circular depressions likely formed by the rapid dissolution of a buried body of gypsum. 210Pb and 137Cs inventories and varve counting indicate high rates of sedimentation (1-2 cm year-1). The annually layered sediment is interrupted by turbidites of two types: a darker-colored turbidite, enriched in lake-derived biogenic constituents, and interpreted as a seismite, and a lightercolored type, enriched in catchment-derived constituents, interpreted as a flood layer. Comparison of our 137Cs-determined layer ages with a catalog of twentieth century earthquakes shows that an earthquake on the Motagua fault in 1976 generated a conspicuous darker-colored turbidite and slumped deposits in separate parts of the lake. The entire earthquake inventory further reveals that mass movements in the lake are triggered at Modified Mercalli Intensities higher than V. Tropical cyclonic depressions known to have affected the lake area had limited effect on the lake, including Hurricane Mitch in 1998. One storm however produced a significantly thicker flood layer in the 1940s. This storm is reportedly the only event to have generated widespread slope failures in the lake catchment. It is thus inferred that abundant landsliding provided large amounts of concentrated sediment to the lake, through hyperpycnal flows

We report here the first inventory of mercury (Hg) contamination in the region of Kedougou, Senegal, where mercury (Hg) is used for gold amalgamation in artisanal small-scale gold mining (ASGM) activities. Sediment cores were sampled during the dry and wet seasons, and at different locations along the Gambia River in the Kedougou region to evaluate the spatio-temporal trends of Hg distribution related to ASGM activities. The sediment samples were analysed for total mercury and trace element concentrations (Cr, Cu, Zn, Pb, As, and Sc). The results highlight high concentrations of total Hg (reaching up to 9.9 mg kg− 1) in sediment cores sampled in the vicinity of ASGM operations, with the highest values reported for the dry season. The calculation of the Hg Enrichment Factor (EF) using Sc as refractory element confirms high enrichments around active sites of gold mining being proportional to the density of miners and the duration of mining activities. The Hg spatial distribution reveals a very local contamination and a limited downstream dispersion of the contaminant. The high Hg concentrations obtained at ASGM sites largely exceed the Sediment Quality Guidelines (SQGs) and the Probable effect concentration (PEC) for the Protection of Aquatic Life recommendation. Our results demonstrate that the ASGM activities discharged large amounts of Hg into the Gambia River ecosystem and that the accumulation of Hg in sediments may represent a significant human health risk and a potential source of toxicity for aquatic organisms.

On Ile de Groix, Variscan metamorphic former tholeiitic and alkaline basalts occur as glaucophane-eclogites, blueschists and greenschists in isolated lenses and layers within metapelites. Whole-rock δ18OSMOW values of the metabasites show limited variations (10.4–12.0‰) and no systematic differences among rock types and metamorphic grades. This provides no argument for large-scale blueschist-to-greenschist transformation driven by infiltration of externally derived fluids. Metamorphic mineralogical changes should have been triggered by internal fluids. Element variations in interlayered blue- and greenschists can be attributed to magmatic fractionation. Assemblages with garnet, clinopyroxene and glaucophane of a high-pressure/low-temperature (HP–LT) metamorphism M1, and NaCa-amphiboles (barroisite, magnesiohornblende, actinolite) of a medium-pressure/medium-temperature metamorphism M2 crystallized during deformation D1. Detailed core-rim zonation profiles display increasing and then decreasing AlIV in glaucophane of M1. NaCa-amphiboles of M2, mantling glaucophane and crystallized in porphyroblasts, show first increasing, then decreasing, AlIV and AlVI. Empirically calibrated thermobarometers allowed P–T path reconstructions. In glaucophane-eclogites of a metamorphic zone I, a prograde evolution to M1 peak conditions at 400–500°C/10–12 kbar was followed by a retrograde P–T path within the glaucophane stability field. The subsequent M2 evolution was again prograde up to >600°C at 8 kbar and then retrograde. Similarly, in metamorphic zones II and III, prograde and retrograde paths of M1 and M2 at lower maximal temperatures and pressures exist. The almost complete metamorphic cycle during M2 signalizes that the HP–LT rocks escaped from an early erosion by a moderate second burial event and explains the long-lasting slow uplift with low average cooling rates.

The Mont-Chemin region at the NE extreme of the Mont-Blanc massif, Canton Valais, Switzerland is predominantly comprised of the granitic rocks of the Mont-Blanc intrusive rock suite and the Mont-Blanc basement gneisses. Fluid inclusions, fluid-mineral equilibria, stable-isotope and radiogenic-isotope studies have been used to derive pressure, temperature, age (PTt) and fluid-composition constraints for a number of Alpine events. The earliest of these events is recorded in a paragonite-katophorite schist hosted within the basement gneisses. The paragonites yield a 40 Ar/ 39 Ar age of 47 Ma. Mineral thermobarometry is consistent with formation temperatures in excess of 300 degrees C, with minimum pressures of 1500 bars. A well-defined pressure-temperature uplift path is recorded in minerals hosted by veins of different generations. The overall PTt path defines a geothermal gradient of 25 degrees C/km, but the younger portions of this PTt path are consistent with geothermal gradients slightly in excess of 50 degrees C/km, similar to those observed to the East along the Rhone-Simplon line.

The lower Austroalpine orthogneiss-micachist complex of the Sopron-Fertorakos area of W. Hungary contains Mg-chlorite-muscovite-quartzphyllites (leuco- phyllite) and Mg-chlorite-bearing kyanite quartzites whose chemical compositions differ greatly from their surrounding rocks. Formation of leucophyllites took place in shear zones and was associated with depletion in alkalies and iron and enrichment of magnesium and H2O. Mg-zonation of relict igneous muscovites of leucophyllites and changes in the whole rock chemical compositions suggest Mg-metasomatism. Material gains and losses have been assessed using the composition-volume relationship approach. Proceeding from metagranite through transition rocks to leucophyllites, MgO, H2O, FeO, and alkalies show continuously increasing dispersion in isocon plots with Mg-enrichment even in sheared gneiss not in contact with leucophyllite. The metasomatic processes that formed the Mg-rich rocks may be similar to those responsible for the formation of high pressure whiteschists in the Central and Western Alps. The geochemical characteristics of the Dora Maira whiteschists (Italy) and their country gneisses are very similar to those of the Sopron leucophyllites, supporting the theory that Mg-metasomatism produced the whiteschist chemistry. On the basis of oxygen isotope compositions of relict igneous muscovites, the precursor granitic rock had a δ18O value around 13‰ proving its crustal anatectic origin. The leucophyllites have whole rock oxygen isotope compositions around 8.5‰ which is in conflict with the theory of an Mg-rich sedimentary protolith. Rather, the low δ18O values reflect fluid/rock interaction with a low δ18O fluid. Quartz-mineral oxygen isotope fractionations yield a metamorphic temperature of 560 ± 30 °C which agrees with earlier estimates from mineral stabilities. Silicon contents of phengites correspond to a metamorphic pressure of ∼13 GPa at this temperature indicating eclogite facies metamorphism. The fluids in equilibrium with leucophyllites had oxygen isotope compositions around 7.9‰, similar to those calculated for the ultrahigh pressure Dora Maira whiteschists (7.6‰), further supporting the genetic link between the leucophyllites and whiteschists. Hydrogen isotope compositions of mixed white mica + chlorite samples from leucophyllites range from −40 to −35‰, correlating with chlorite contents. The calculated endmember chlorite and white mica have δD values of −30 and −40‰, respectively. The similar δD values of the white micas in leucophyllites, gneisses and metagranites suggest an overall equilibration with respect to H isotopes. The calculated δD value of the fluid is approximately 0‰, suggesting a seawater origin. This conclusion was also reached for the Dora Maira whiteschists. A possible fluid source that satisfies both metasomatic and isotopic data is dehydration of hydrothermally altered oceanic crust. The mafic–ultramafic complex of the Alpine Penninic unit underlying the Austroalpine nappes is a likely candidate. The subduction and subsequent dehydration of the ophiolite series would supply the Mg-rich fluids whose migration brought about the metasomatic alteration of the overlying gneiss-micaschist complexes.

International audience; This study aimed at identifying the extent and type of contamination of a former lead smelting site in the area of Marseille, France, dating from the industrial revolution, and to evaluate environmental hazards and opportunities for phytoremediation, a promising sustainable technology. Amongst the native plants growing in this semiarid shrub ecosystem, two perennials Globularia alypum L. and Rosmarinus officinalis L were selected. Twenty-one soil/plant couples were collected and seventeen additional soil samples were added to better characterize the soil pollution of the area. A multi-contamination by Pb, As, Sb, Zn, Cu was demonstrated, with huge variations within the contamination levels. The soils highest concentrations were encountered along the horizontal chimney and on the slag heaps area. However, both sites differed from each other. The former was characterized by the highest Pb, As and Sb concentrations that could reach 130, 7.0 and 9.0 g kg(-1) respectively, the latter, by high Cu, Fe, Mn, S concentrations, even if it was also heavily contaminated by Pb and Zn. G. alypum and R. officinalis were shown to be metal-tolerant and to accumulate trace metals and As. Due to the low bioconcentration and translocation factors determined, both species may not be used for phytoextraction, but seem to be good candidates for phytostabilization. (C) 2013 Elsevier B.V. All rights reserved.

The use of pesticides may lead to environmental problems, such as surface water pollution, with a risk for aquatic organisms. In the present study, a typical vineyard river of western Switzerland was first monitored to measure discharged loads, identify sources, and assess the dynamic of the herbicide glyphosate and its metabolite aminomethylphosphonic acid (AMPA). Second, based on river concentrations, an associated environmental risk was calculated using laboratory tests and ecotoxicity data from the literature. Measured concentrations confirmed the mobility of these molecules with elevated peaks during flood events, up to 4970 ng/L. From April 2011 to September 2011, a total load of 7.1 kg was calculated, with 85% coming from vineyards and minor urban sources and 15% from arable crops. Compared with the existing literature, this load represents an important fraction (6-12%) of the estimated amount applied because of the steep vineyard slopes (∼10%). The associated risk of these compounds toward aquatic species was found to be negligible in the present study, as well as for other rivers in Switzerland. A growth stimulation was nevertheless observed for the algae Scenedesmus vacuolatus with low concentrations of glyphosate, which could indicate a risk of perturbation in aquatic ecosystems, such as eutrophication. The combination of field and ecotoxicity data allowed the performance of a realistic risk assessment for glyphosate and AMPA, which should be applied to other pesticide molecules.

The top soil of a 14.5 km 2 region at la Chaux-de-Fonds in the Swiss Jura is exceptionally rich in cadmium. It contains an average of 1.3 mg per kg of soil. The spatial distribution of the metal has no simple pattern that could be explained by atmospheric deposition or agricultural practices. Thin soil contained most of its Cd at the surface; in thicker soil Cd is mainly concentrated between 60 and 80 cm depth. No specific minerals or soil fractions could account for these accumulation, and the vertical distribution of Cd is best explained by leaching from the topsoil and further adsorption within layers of nearly neutral pH. The local Jurassic sedimentary rocks contained too little Cd to account for the Cd concentrations in the soil. Alpine gravels from glacial till were too sparse in soils to explain such a spreading of Cd. Moreover this origin is contradictory with the fact that Cd is concentrated in the sand fraction of soils. The respective distributions of Fe and Cd in soils, and soil fractions, suggested that the spreading of iron nodules accumulated during the siderolithic period (Eocene) was not the main source of Cd. Atmospheric deposition, and spreading of fertiliser or waste from septic tanks seem the only plausible explanation for the Cd concentrations, but at present few factors allow us to differentiate between them.

The aim of our survey was to assess the effect of irrigation water of the microbiological quality on the production chain of lettuce in the Dakar area. Microbiological analysis showed that 35% of irrigation water was contaminated by Salmonella spp. between the two water-types used for irrigation (groundwater and wastewater), no significant difference (p>0.05) in their degree of contamination was found. The incidence of different types of irrigation water on the contamination rate of lettuces from the farm (Pikine and Patte d’Oie) was not different either (p>0.05). However, the contamination rate of lettuce from markets of Dalifort and Grand-Yoff that were supplied by the area of Patte d’Oie was greater than those of Sham and Zinc supplied by Pikine (p

The aim of this survey is to assess the microbiological impact of irrigation water on lettuces produced on two urban agricultural sites and sold on markets; 6 and 7%, respectively, of lettuces coming from the sites of Pikine and Patte d'Oie were Salmonella spp. positive. Lettuces irrigated with shallow groundwater (“Ceanes” water) were more contaminated (8% at both Pikine and Patte d'Oie sites) compared to those irrigated with wastewater (4% at Pikine) or well water (5% at Patte d'Oie). As for the lettuces in marketplaces, their contamination seems to depend on the type of treatment occurring before sale. Lettuces previously washed in the “Ceanes” were more contaminated than those rinsed with tap water at the marketplace. Salmonella spp. have been isolated from all marketplaces. However, the rates of contamination in markets surrounding Patte d'Oie are higher (9 and 11% at Grand Yoff and Dalifort) than those surrounding Pikine (4 and 2% at Zinc and Sham) or Rufisque, the control (2%). Our results confirm that the reuse of wastewater in irrigation is an alternative to animal manure. Its risk of microbial contamination can be significantly reduced by washing the vegetables with tap water before they are sold. Copyright © 2010 John Wiley & Sons, Ltd. Le but de notre etude est d'evaluer les impacts des eaux d'irrigation sur la qualite microbiologique des laitues produites par deux sites d'agriculture urbaine et vendues dans les marches; 6 et 7% des laitues provenant des sites de Pikine et de Patte d'Oie ont ete positives pour Salmonella. Les laitues irriguees avec les eaux de Ceanes ont ete plus contaminees (8% a Pikine et 8% a Patte d'Oie) par rapport a celles irriguees avec les eaux usees (4% a Pikine) et les eaux de puits (5% a Patte d'Oie). Dans les marches, la sur-contamination des laitues semble dependre du type de traitement anterieur a la vente. Les laitues lavees dans les Ceanes ont des taux de contamination plus eleves que celles rincees au marche avec l'eau de robinet. Salmonella spp. a ete isolee dans les laitues provenant de tous les marches. Cependant, les taux de contamination dans les marches qui s'approvisionnent a Patte d'Oie sont plus eleves (9 et 11% pour les marches Grand-Yoff et Dalifort) que ceux de Pikine (4% marche Zinc et 2% a Sham) et Rufisque (2%). Cette etude montre que la reutilisation des eaux usees traitees peut constituer une alternative en favorisant la reduction de l'utilisation des fumiers organiques. Le prelavage des laitues avec l'eau de robinet permet une forte diminution de la contamination. Copyright © 2010 John Wiley & Sons, Ltd.

The long-term impact of irrigation on a Mediterranean sandy soil irrigated with Treated wastewater (TWW) since 1980 was evaluated. The main soil properties (CEC, pH, size distribution, exchangeable cations and chloride, hydraulic conductivity) as well as the organic matter and Cu, Cr and Pb speciation in an irrigated soil and a non-irrigated control soil at various soil depths were monitored and compared during a 2 years experiment. In this first part, the evolution of the physico-chemical soil properties was described. The irrigation with TWW was beneficial with regard to water and nutrient supplying. All the exchangeable cations other than K + were higher in the irrigated soil than in the reference one. A part of the exchangeable cations was not fixed on the exchange complex but stored as labile salts or in concentrated soil solution. Despite the very sandy soil texture, both saturated and unsaturated hydraulic conductivity exhibited a significant diminution in the irrigated soil, but remained high enough to allow water percolation during rainy periods and subsequent leaching of accumulated salts, preventing soil salinization. In the irrigated soil, exchangeable sodium percentage (ESP) exhibited high values (20% on average) and the soil organic C was lower than in the reference. No significant effect was noticed on soil mineralogical composition due to irrigation.

L’agriculture urbaine de la région de Dakar est un secteur en plein essor. À cause de la salinisation progressive des eaux de la nappe peu profonde (eaux de Céanes ), des eaux usées brutes sont utilisées pour irriguer les champs. L’objectif de notre étude est d’évaluer la qualité chimique et microbiologique des eaux de la nappe sous-jacentes aux champs irrigués et d’identifier les sources de pollution. Notre travail a été effectué dans les sites de Pikine et de Patte d’Oie.L’analyse de la qualité chimique des eaux d’arrosage a montré qu’à Pikine, la conductivité des eaux de Céanes est plus élevée (4822±2411 µS cm-1) par rapport à celle des eaux usées (3579±1242 µS cm-1 ; p, In Dakar capital city of Senegal, the urban agriculture is in high expansion. Since the progressive increase of salinity in the local groundwater (Céanes water), raw wastewater is used to water the crops. The objective of this study is to assess chemical and microbiological quality of the groundwater underlying the irrigated plots and to identify the sources of pollution. This work was carried out in the sites of Pikine and Patte d’Oie in Dakar Senegal.Chemical analysis of irrigation water showed that in Pikine, the conductivity of Céanes water was higher (4822±2411 µS cm-1) than those of the wastewater (3579±1242 µS cm-1 ; p

In the Alps, debris flow deposits generally contain < 5% clay-size particles, and the role of the surface-charged < 2 mu m particles is often neglected, although these particles may have a significant impact on the rheological properties of the interstitial fluid. The objective of this study was to compare debris flow deposits and parent materials from two neighbouring catchments of the Swiss Alps, with special emphasis on the colloidal constituents. The catchments are small in area (4 km(2)), 2.5 km long, similar in morphology, but different in geology. The average slopes are 35-40%. The catchments were monitored for debris flow events and mapped for surface aspect and erosion activity. Debris flow deposits and parent materials were sampled, the clay and silt fractions extracted and the bulk density, < 2 mm fraction bulk density, particle size distribution, chemical composition, cation exchange capacity (CEC) and mineralogy analysed. The results show that the deposits are similar to the parent screes in terms of chemical composition, but differ in terms of: (i) particle size distribution; and (ii) mineralogy, reactivity and density of the < 2 mm fraction. In this fraction, compared with the parent materials the deposits show dense materials enriched in coarse monocrystalline particles, of which the smallest and more reactive particles were leached. The results suggest that deposit samples should not be considered as representative of source or flow materials, particularly with respect to their physical properties.

The distribution of low molecular weight carboxylic acids (LMWCA) was investigated in pore water profiles from two porphyry copper tailings impoundments in Chile (Piuquenes at La Andina and Cauquenes at El Teniente mine). The objectives of this study were (1) to determine the distribution of LMWCA, which are interpreted to be the metabolic byproducts of the autotroph microbial community in this low organic carbon system, and (2) to infer the potential role of these acids in cycling of Fe and other elements in the tailings impoundments. The speciation and mobility of iron, and potential for the release of H+ via hydrolysis of the ferric iron, are key factors in the formation of acid mine drainage in sulfidic mine wastes. In the low-pH oxidation zone of the Piuquenes tailings, Fe(III) is the dominant iron species and shows high mobility. LMWCA, which occur mainly between the oxidation front down to 300 cm below the tailings surface at both locations (e.g., max concentrations of 0.12 mmol/L formate, 0.17 mmol/L acetate, and 0.01 mmol/L pyruvate at Piuquenes and 0.14 mmol/L formate, 0.14 mmol/L acetate, and 0.006 mmol/L pyruvate at Cauquenes), are observed at the same location as high Fe concentrations (up to 71.2 mmol/L Fe(II) and 16.1 mmol/L Fe(III), respectively). In this zone, secondary Fe(III) hydroxides are depleted. Our data suggest that LMWCA may influence the mobility of iron in two ways. First, complexation of Fe(III), through formation of bidentate Fe(III)-LMWCA complexes (e.g., pyruvate, oxalate), may enhance the dissolution of Fe(III) (oxy)hydroxides or may prevent precipitation of Fe(III) (oxy)hydroxides. Soluble Fe(III) chelate complexes which may be mobilized downward and convert to Fe(II) by Fe(III) reducing bacteria. Second, monodentate LMWCA (e.g., acetate and formate) can be used by iron-reducing bacteria as electron donors (e.g., Acidophilum spp.), with ferric iron as the electron acceptor. These processes may, in part, explain the low abundances of secondary Fe(III) hydroxide precipitates below the oxidation front and the high concentrations of Fe(II) observed in the pore waters of some low-sulfide systems. The reduction of Fe(III) and the subsequent increase of iron mobility and potential acidity transfer (Fe(II) oxidation can result in the release of H+ in an oxic environment) should be taken in account in mine waste management strategies.

The Mont Collon mafic complex is one of the best preserved examples of the Early Permian magmatism in the Central Alps, related to the intra-continental collapse of the Variscan belt. It mostly consists (> 95 vol.%) of ol + hy-normative plagioclase-wehrlites, olivine- and cpx-gabbros with cumulitic structures, crosscut by acid dikes. Pegmatitic gabbros, troctolites and anorthosites outcrop locally. A well-preserved cumulative sequence is exposed in the Dents de Bertol area (center of intrusion). P – T calculations indicate that this layered magma chamber emplaced at mid-crustal levels at about 0.5 GPa and 1100 °C. The Mont Collon cumulitic rocks record little magmatic differentiation, as illustrated by the restricted range of clinopyroxene mg-number (Mg# cpx = 83–89). Whole-rock incompatible trace-element contents (e.g. Nb, Zr, Ba) vary largely and without correlation with major-element composition. These features are characteristic of an in-situ crystallization process with variable amounts of interstitial liquid L trapped between the cumulus mineral phases. LA-ICPMS measurements show that trace-element distribution in the latter is homogeneous, pointing to subsolidus re-equilibration between crystals and interstitial melts. A quantitative modeling based on Langmuir's in-situ crystallization equation successfully duplicated the REE concentrations in cumulitic minerals of all rock facies of the intrusion. The calculated amounts of interstitial liquid L vary between 0 and 35% for degrees of differentiation F of 0 to 20%, relative to the least evolved facies of the intrusion. L values are well correlated with the modal proportions of interstitial amphibole and whole-rock incompatible trace-element concentrations (e.g. Zr, Nb) of the tested samples. However, the in-situ crystallization model reaches its limitations with rock containing high modal content of REE-bearing minerals (i.e. zircon), such as pegmatitic gabbros. Dikes of anorthositic composition, locally crosscutting the layered lithologies, evidence that the Mont Collon rocks evolved in open system with mixing of intercumulus liquids of different origins and possibly contrasting compositions. The proposed model is not able to resolve these complex open systems, but migrating liquids could be partly responsible for the observed dispersion of points in some correlation diagrams. Absence of significant differentiation with recurrent lithologies in the cumulitic pile of Dents de Bertol points to an efficiently convective magma chamber, with possible periodic replenishment.

Die Beschaftigung mit spirituellen Bedurfnissen von Patienten gehort nicht zum ublichen arztlichen Aufgabengebiet. Doch kann dieser Aspekt einfach auf die Klinikseelsorge abgeschoben werde? Die Erfahrung zeigt, dass Patienten mit ihrem Arzt auch uber existentielle Fragen sprechen mochten.

Studies on environmental pollution in a given region often suffer from the lack of reliable information on the natural level of trace elements. The natural contribution to the trace element contents and fluxes of local and regional ecosystems strongly depends on the local composition of the lithosphere, i.e. the dominating rock type. The dispersion of trace elements in the different environmental compartments is mainly governed by weathering and mass transport. Based on examples from Central Europe, this paper gives an insight into the typical natural input of six major, geochemically defined rock types (“natural background”). It also presents two cases of regional “natural contamination” related to ore deposits. Each rock type contributes in a characteristic manner to the major and trace element budget of soils, sediments, plants, surface and ground waters. Whereas well soluble elements such as Ca, Sr, Mg, Na and K are enriched in the water phase, less soluble elements such as Al, Fe and in part Si and most trace elements are enriched in the soil compartment. In the latter, these elements are either part of, or are adsorbed on organic material, oxy-hydroxides or clay type minerals. From soils, trace elements are transported either to plants or to ground waters. The extent and manner to which chemical elements of the underlying rocks are dispersed in their surroundings depends first of all on the chemical composition of the parent material, varying greatly from one rock type to the other. Secondly, the typical pH created in the soil and water compartments strongly influences the sorption behavior and thus retention or release of specific elements. Soils formed on silicate rocks usually exhibit acid conditions (pH 4–6.5), related soil and ground waters typically are near neutral (pH 6.5–7.5). However, soils and waters related to carbonate rock environments are usually neutral to alkaline (pH 7–8.5). Soils on granitic silicate rocks have been found to be slightly enriched in Zr, Ti, Pb and Rb and often host ore deposits rich in U or As, which influence the water and sediment composition of whole catchment areas. Basaltic silicate rocks enrich the soils typically in Sr, Ti, Fe, V, Cr, Ni, Cu and Zn in concentrations up to three times those of granites. Mg-rich silicate rocks, such as peridotites and serpentinites, typically enrich soils, plants and waters with very high amounts of Mg, Fe, Cr, Co, Ni and V, but other trace elements remain very low. Al-rich silicate rocks, such as shales and micaschists, are often rich in sulfur and metal traces such as Zn, Pb, As and Cd. In contrast, carbonate dominated rocks, such as limestones or sulfate bearing dolomites, typically contribute to enrich their environment with Mn, F, S, Cl, Ba, Sr, As, Cd and radon. In conclusion, insufficient knowledge of this natural contribution can lead to misinterpretations of contaminated sites, especially for elements such as Ni, Cr, Zn, V, Cd and As.

The names of some of the authors of this section were inadvertently omitted in the original publication. We regret this omission and provide all of the authors’ names here: Wolkersdorfer, Christian; Bowell, Rob; O’Sullivan, Aisling D.; Diels, Ludo; Grmela, Arnost; Rapantova, Nad’a; Pfeifer, Hans-Rudolf; Dold, Bernhard; Midžic, Sanda; Silajdžic, Irem; Pinto, Marina M. S. Cabral; Silva, Maria Manuela Vinha G.

Most of the over one-hundred known metaperidotite lenses of the high grade metamorphic part of the Central Alps show metasomatic features like concentric zoning and composite veining. These indicate that an important hydrothermal event took place during an early stage of the uplift which followed the pressure peak of the regional metamorphism, at approximately 580–650 deg C and 4–6 kbar. Some of the most conspicuous veins occur in the Cima di Gagnone region in the North-Eastern Verzasca Valley in Switzerland. They are usually no longer than 2 to 5 meters and vary in width from 1 to 50 centimeters. Geometrically two types can be distinguished: The first type starts in the mafic marginal (“black wall”) zone of a lens or in mafic layers cross-cutting a lens. The second one has a tensioncrack shape and begins and ends anywhere in the ultramafic host rock. The veins are usually symmetrically zoned, composed of a central zone with several replacement zones on both sides. Based on their dominant mineral phases, 4 vein types can be distinguished: (A) Mg-amphibole dominated, (B) tremolite- chlorite dominated, (C) chlorite- talc dominated, and (D) talc- carbonate dominated veins. The veins are interpreted to represent the second stage of a hydrothermal metamorphism during which rapid deformation led to brittle behaviour of the ultramafic host rock. Fluid compositions deduced from mineral data with the aid of activity- activity-X( CO2) — diagrams indicate locally steep gradients in CO2, SiO2, iron, calcium and aluminium. A tentative interpretation of the changing mineral compositions as a function of the distance from the vein center indicates a diffusion-dominated mass transfer mechanism. In contrast to more acid rocks, aluminium seems to be easily transported in the high pH- and low fO2-conditions of the fluids present in these ultramafic rocks.

The high grade metamorphic part of the Penninic zone of the Central Alps is characterized by 1 to 100 meters large ultramafic lenses of originally harzburgitic composition. A usually concentric zonation of these lenses indicates a syntectonic hydrothermal alteration related to the regional metamorphism. Five different zones can be distinguished : 1) original rock (mainly olivine-enstatite-chlorite-Cr-Fe-spinel), 2) hydrated zone (olivine-talc-chlorite-Cr-Fe-spinel ± amphibole), 3) hydrated and carbonatized zone (talc-magnesite-chlorite-amphibole-Fe-spinel), 4) zone strongly enriched in Ca, Al and Si (amphibole-chlorite-Fe-spinel ± magnesite, pentlandite), 5) complex marginal zonation (mono-and bimineralic zones of biotite, amphibole and plagioclase). The spectacular zone boundaries allow reconstruction of fluid-rock reactions in detail. Using temperature and pressure estimations of 580-650 °C and 5 kbar, the fluid composition in the various zones can be estimated : CO₂, O₂ and S₂ increase towards the margins of the lenses, X[CO₂] showing values between 0 and 0.9. Aqueous species concentrations like SiO₂, Ca, A1 and Mg also increase towards the margins. The pH is predicted to vary between 5 and 7. Direction and extent of mass fluxes are estimated on the basis of field observations and various assumptions concerning mass and volume of the zones. Whereas Mg and Fe appear to be internally redistributed, large amounts of Si, Al and Ca are predicted to move in from felsic and mafic country rocks, leading to a volume increase of up to 30 %. The only slightly affected country rocks and stable isotope data exclude a local origin of these elements and suggest a more distant source of the fluid phase. The dominant mass transport mechanism for aqueous species is assumed to be infiltration in a fluid pressure gradient. Locally at zone boundaries, composition — distance plots for Fe indicate a combination of diffusion and infiltration., Le domaine le plus fortement métamorphique de la zone pennique des Alpes centrales est caractérisé par la présence de lentilles ultramafiques métriques à hectométriques d'origine harzburgitique. On observe dans celles-ci une zonation souvent concentrique indiquant une altération hydrothermale liée au métamorphisme régional. Du centre au bord, cinq zones ont été distinguées : 1) roche originale (olivine-enstatite-chlorite-Fe-Cr-Spinelle), 2) zone hydratée (olivine-talc-chlorite-Cr-Fe-spinelle), 3) zone hydratée et carbonatée (talc-magnésite-chlorite-amphibole-Fe-spinelle), 4) zone fortement enrichie en Ca, Al et Si (amphibole-chlorite-Fe-spinelle ± magnésite-pentlandite), 5) zone marginale complexe (diverses zones mono-et biminérales à biotite, amphibole ou plagioclase). Les limites de chaque zone sont très spectaculaires et significatives ; elles permettent de reconstruire les réactions d'interaction entre le fluide et la toche. Sur la base de conditions de température et de pression de 580-650 °C et 5 kbar, la composition du fluide dans les diverses zones peut être déduite et nous constatons que CO₂, O₂ et S₂ augmentent vers l'extérieur des lentilles, X[CO₂] variant entre 0 et 0,9. Les concentrations des espèces aqueuses telle que SiO₂, Ca, Al et Mg augmentent également vers l'extérieur. Le pH varierait entre 5 et 7. A partir de critères de terrain et d'hypothèses sur les modifications de volume et de masse de chaque zone, le sens et la quantité de transferts de masse sont déterminés. Alors que Mg et Fe resteraient constants, de grandes quantités de Si, Al et Ca d'origine externe pénétreraient dans les lentilles ultramafiques en provoquant jusqu'à 30 % d'augmentation de volume. Le fait que les roches encaissantes (gneiss, amphibolite, marbre) ne soient guère altérées indique une origine plus lointaine de la phase fluide, ce qui est confirmé par des analyses d'isotopes stables. Le mécanisme dominant de transport des espèces aqueuses serait celui d'infiltration dans la direction du gradient de pression de la phase fluide. Localement, à la limite des zones, le changement de la composition avec la distance de certains minéraux indique une combinaison de diffusion et infiltration., Pfeifer Hans-Rudolf. A model for fluids in metamorphosed ultramafic rocks III. Mass transfer under amphibolite facies conditions in olivine˗enstatite rocks of the Central Alps, Switzerland. In: Bulletin de Minéralogie, volume 104, 6, 1981. 26e congrès géologique international – Paris – Juillet 1980. Section Minéralogie. Section Pétrographie : symposium « Interactions fluides, minéraux, roches ».