Lead in food and soil from a mining area in Brazil and human exposure

During the last century, several lead mines and a metal smelter were in production in the Upper Ribeira Valley, southeastern Brazil. After fifty years of activity, the refinery was shut down in November 1995 and, thereafter the last mines in production were closed. Since 1998, a multidisciplinary research group has carried out an ambitious investigation among the population of five municipalities in the Ribeira Valley （sampled population of 472 children and 523 adults） to assess the human exposure to lead. The highest blood lead levels were found among the population of two villages in the vicinity of the smelter where soil and indoor-dust are highly contaminated. During the present study, the lead contents of several food species that are part of local population diet were investigated. Greens, vegetables, corn, chicken eggs and cow milk, were sampled in two occasions, July 2004 and February 2005. The analytical procedures included burning of organic matter, pre-concentration of lead and, finally, determination by AAS using background correction. The quantification limit was 0.05 μg/g Pb. Soil samples were also collected and analyzed by X-ray fluorescence spectroscopy with a quantification limit of 2 μg/g Pb. The results are very impressing since 100% of greens, vegetables and eggs yielded lead concentrations exceeding the upper limits established by Brazilian regulations whereas milk and maize samples presented lead contents below the regulated limit of 0.05 μg/g Pb. Lead concentrations in soil varied between 156 and 1292 μg/g Pb, resembling the results of previous studies and far exceeding the threshold of 200 μg/g Pb indicated as the intervention value. Lead contents in some species vary consistently with lead concentrations in soils, however, other factors may account for the bioavailability of lead and its intake by plants, like the soil pH, its cationic exchange capacity, clay and organic matter contents, characteristics of the plant species itself, climate, among others.     

Deformation inside a paleosubduction channel – Insights from microstructures and crystallographic preferred orientations of eclogites and metasediments from the Tauern Window,Austria

The Eclogite Zone, of the Tauern Window is an exhumed subduction channel comprising eclogites with different grades of retrogression in a matrix of high-pressure metasediments. The rocks were exposed to 600 °C and 20–25 kbars, and then retrogressed during their exhumation, first under blueschist facies and later under amphibolite facies metamorphism. To gain insights into the deformation within the subduction channel during subduction and exhumation, both fresh and retrogressed eclogites, as well as the surrounding metasediments were investigated with respect to their deformation microstructures and crystallographic preferred orientations (CPOs). Pristine and retrogressed eclogites show grain boundary migration and subgrain rotation recrystallization microstructures in omphacite. A misorientation axes analysis reveals the activity of complementary deformation mechanisms including grain boundary sliding and dislocation creep. The omphacite CPOs of the eclogites correspond to dominant SL-fabrics characteristic of plane strain deformation, though there are local variations towards flattening or constriction within the paleosubduction channel. The glaucophane CPOs in retrogressed eclogites match those of omphacite, suggesting that a constant strain geometry persisted during exhumation at blueschist facies conditions. Plastic deformation of the host high-pressure metasediments outlasted that of the eclogites, as indicated by white mica fabrics and quartz CPO. The latter is consistently asymmetric, pointing to the operation of non-coaxial deformation. The microstructures and CPO data indicate a continuous plastic deformation cycle with eclogite and blueschist facies metamorphism related to subduction and exhumation of the different rock units.     

Micro- and nano-inclusions in a superdeep diamond from São Luiz,Brazil

We report cloudy micro- and nano-inclusions in a superdeep diamond from São-Luiz, Brazil which contains inclusions of ferropericlase (Mg, Fe)O and former bridgmanite (Mg, Fe)SiO₃ and ringwoodite (Mg, Fe)₂SiO₄. Field emission-SEM and TEM observations showed that the cloudy inclusions were composed of euhedral micro-inclusions with grain sizes ranging from tens nanometers to submicrometers. Infrared absorption spectra of the cloudy inclusions showed that water, carbonate, and silicates were not major components of these micro- and nano-inclusions and suggested that the main constituent of the inclusions was infrared-inactive. Some inclusions were suggested to contain material with lower atomic numbers than that of carbon. Mineral phase of nano- and micro-inclusions is unclear at present. Microbeam X-ray fluorescence analysis clarified that the micro-inclusions contained transition metals (Cr, Mn, Fe, Co, Ni, Cu, Zn) possibly as metallic or sulfide phases. The cloudy inclusions provide an important information on the growth environment of superdeep diamonds in the transition zone or the lower mantle.     

Native Ta and in from a probe of regolith AS “Luna-24”

Doklady Earth Sciences -     

Asbestiform and non-asbestiform morphologies in a talc and vermiculite mine from the province of Córdoba (Argentina): a case study

In this work, a talc and vermiculite mine from the province of Córdoba (Argentina) was investigated with special emphasis on the occurrence of asbestiform and non-asbestiform phases. The meta-ultramafic rock was studied by a multimethodological approach, complementing field studies with petrographic-mineralogical, compositional and morphological analyses. Samples were examined by stereomicroscopy, polarizing light microscopy, SEM–EDS, XRD, DSC-TGA and FTIR. Complementary, compositional and textural analyses were performed with FE-SEM–EDS and EPMA. Talc-rich veins with a laminar and fibrous appearance were at first recognized. However, the fibrous morphology observed both in the field and by microscopy is due to an apparent habit because of the sample orientation. To avoid erroneous interpretations, studies by secondary electron images (SEM) are fundamental to carrying out this type of analysis. Tremolite was identified in different zones of the outcrop; however, only ~40% of the crystals located in the vermiculite zone have dimensions to be considered as asbestiform fibres in the range of respirable particles. In these types of complex deposits affected by superimposed metamorphic, igneous and deformational events, multimethodological approaches are necessary to develop models of occurrence of asbestiform morphologies that may be applicable to other with similar characteristics.     

Stream water chemistry and nitrogen export from a subtropical-forested catchment in Hunan in central-southern China

Chemistry of stream water and nitrogen export and net nitrogen budget in a subtropical evergreen Shaoshan forested catchment were analyzed and evaluated concurrently for 4 years in central-south China. pH value in stream water varied monthly from 6.57 to …     

Characterization of a chalcopyrite from Brazil by Mössbauer spectroscopy and other physicochemical techniques

We studied a chalcopyrite from a Cu ore deposit in Rio Grande do Sul, Brazil, by Mössbauer spectroscopy at room temperature and 110 K. Supporting methods to check for sample purity and to characterize further sample properties were slow-scanning X-ray powder diffraction and optical and microprobe analyses of polished sections of selected grains. Chemical analyses obtained using a scanning electron microscope equipped with an energy-dispersive X-ray spectrometer showed the sample to consist of homogeneous and essentially stoichiometric chalcopyrite (CuFeS₂). Mössbauer spectra taken at both the above temperatures consist of asymmetric magnetically ordered patterns with unequal intensities of the line pairs 1–6 and 2–5, pointing to the existence of non-equivalent or multiple Fe sites. Least-squares fittings evidenced that the resonance intensity ratio of subspectrum with lower quadrupole shift (indicative of a more symmetric environment) to that with higher shift is 69:31, at room temperature, and 68:32, at 110 K. Rietveld refinement of the XRD data indicates the existence of tetragonal [a = 0.52855(1) and c = 1.0412(1) nm] and cubic [a ₀ = 0.5273(2) nm] modifications in a proportion of 74:26, in good agreement with the Mössbauer data. The saturation magnetization of the sample was 32.7 J/(T kg), confirming the oxidation state of Fe as trivalent and pointing to little to no spin canting.     

Distribution of uranium and thorium in Irtysh River and the upriver wastewater from a rare metal mine impact on it

Uranium and Th are important radioactive elements. Most studies were focused on their environmental impact from uranium deposits and mining sites. But other sorts of mines such as rare metals mines are associated highly with uranium and thorium, too. In China, the Irtysh River is the only river that runs into the Arctic Ocean. The famous Koktokay rare metal pegmatite deposit is located in the headwater region of this river and has been exploited for several decades. The waste ore piled along the riverside as long as several kilometers. The wastewater flom the concentrating plant is discharged into the river directly. In addition, uranium and thorium can be leached from the waste ore into the river in the weathering process. So it is necessary to study the uranium and thorium distribution in the branch and trunk streams of the Irtysh River and the wastewater from the mining site impact on it. In this study, the contents of uranium and thorium in water samples from the Irtysh River and rare metal mine wastewater have been detected directly with ICP-MS. Uranium and thorium distribution and geochemical behaviors in the Irtysh River basin have been studied. The environmental uranium and thorium pollution status in the Irtysh River and wastewater from a rare metal mine impact on it have also been evaluated. The study shows that uranium and thorium contents in wastewater from a rare metal mine are as high as 78.311 μg/L and 0.627 μg/L, respectively, so we should also pay attention to the radioactive pollution from the rare metal mine. The average contents of U and Th in the branch streams of the Irtysh River are 0.572 μg/L and 0.015 μg/L, respectively. At the mean time, in the trunk of the Irtysh River, average thorium content is 0.019 μg/L while U is up to 2.234 μg/L, much higher than the average content （0.0309 μg/L） of the world rivers. From upstream to downstream in the trunk of the Irtysh River, thorium content declines gradually due to dilution by other branches and deposition itself.     

Electronic and magnetic properties of a natural aegirine as observed from its Mössbauer spectra

A natural sample of aegirine, ideally NaFeSi₂O₆, has been studied by transmission Mössbauer spectroscopy in the range 4.2–480?K. At selected temperatures, a longitudinal external field of 60?kOe was applied to the absorber. The sample was observed to order magnetically at 11±1?K. The paramagnetic Mössbauer spectra (MS) show the presence of ～10% Fe²⁺ in the M1 sites of the clinopyroxene structure. These MS have been decomposed into four quadrupole doublets: two minor ones for Fe²⁺ on M1 sites, a dominant one due to Fe³⁺ on M1 sites, and a second ferric component, with a contribution of ～3% and attributable to the tetrahedral sites. Two possibilities concerning the origin of the two distinct Fe²⁺ (M1) doublets are discussed. They are respectively based on inter-valence charge transfer and on the existence of distinct Fe²⁺ orbital configurations at the two M1 sites. Neither of the two models could be firmly excluded. The asymmetry parameter η of the electric field gradient at the Fe³⁺ (M1) sites is close to 1.0 and the quadrupole splitting within 0.34±0.01?mm/s at all temperatures. The MS at 4.2?K shows an asymmetric hyperfine-field distribution for Fe³⁺, with a maximum-probability field of 468?kOe. The maximum-probability field for Fe²⁺ is found to be 220?kOe. The shape of the applied-field MS at 4.2?K implies a static antiferromagnetic ordering and was successfully interpreted by a bidimensional distribution of the magnitude and orientation of the hyperfine field. Finally, the temperature variations of the respective centre shifts and quadrupole splittings could be explained on the basis of existing theoretical models.     

State-of-the art and perspectives of economic geography — taking stock from a German point of view

This article presents an evaluation of the current status of economic geography in general and German economic geography in particular with respect to research topics. A comparison with Anglo-American economic geography, more specifically, its actual research fields are also undertaken on the basis of a bibliometrical analysis of German and international journals dedicated to economic geography. On the basis of this analysis suggested actions are formulated, which could contribute to improved performance of research in German economic geography.     

Examining the cooperative governance of occupational safety and health from a “health footprint” perspective

Natural Hazards - Because of the cross-domain status of labor, a characteristic of mobility is often added to individual occupational safety and health. Cooperative governance of occupational...     

Erosional remnants and pockets evolving from biotic–physical interactions in a Recent lower supratidal environment

Sedimentary structures characterizing tidal depositional systems are not in all cases produced by physical dynamics alone. The activities of epibenthic cyanobacteria such as biostabilization or surface levelling may also play a significant role in structure formation. One example of bio-induced structures are `erosional remnants and pockets', a specific surface morphology that can be observed in the lower supratidal zone of Mellum Island, southern North Sea. This surface relief rises from partwise erosion of a microbial mat-covered and biostabilized tidal surface. On the basis of detailed field measurements of the geometric dimensions of the surface relief, the tidal current system of the area and the history of formation of the morphology can be reconstructed. Erosional remnants and pockets are highly facies indicative and fossil occurrences would help in reconstruction paleo-environments.     

Characterization of red mud derived from a combined Bayer Process and Calcining method for alumina refining

Red mud is the residue of bauxite processing for alumina. Red mud varies in physical, chemical and mineralogical properties due to differing mineral sources and refining processes adopted. In this project, red mud produced using a combined Bayer Process and Calcining （BPC） method was investigated. Red mud samples of varying ages were collected from the red mud storage facilities of the Zhenzhou Changcheng Aluminium Limited. The objective of this study is to （1） characterize the BPC red mud, and （2） examine the effects of this red mud on treating heavy metal-containing water and soil. Red mud samples were analyzed for pH, EC, water extractable salts and exchangeable basic cations, total element composition （by XRF）, mineral composition （by XRD）, micromorphological characteristics （by SEM） and thermogravimetric analysis （TGA）. The results show that the pH of the red mud decreased with increasing duration of storage time. The pH of the fresh, 5-year-old and 10-year-old red mud was 11.58, 10.56 and 9.61, respectively. Sodium dominated among the soluble cations, but the concentration of soluble Na decreased with increasing duration of storage time as a result of leaching. Cation exchange capacity as estimated from the sum of exchangeable cations also decreased with increasing duration of storage time, probably due to the decreasing pH which causes a reduction in negatively charged sites of the red mud. Calcium was the predominant exchangeable cation in the fresh red mud but the concentrations of exchangeable Ca markedly decreased in the old red mud which was dominated by exchangeable Na.XRF results showed that the red mud consists mainly of oxygen, calcium, iron, silicon, aluminium and titanium. Other important elements include sodium, carbon, magnesium and potassium. It is important to note that the red mud also contains elevated concentrations of radioactive elements, predominantly thorium （Th）, cerium （Ce） and rubidium （Rb）. XRD results showed that the major mineral types in the red mud were calcite, perovskite, illite, hematite and magnetite. There is a trend that the contents of magnetite decreased while the contents of hematite increased with increasing storage time, suggesting the conversion of magnetite to hematite. Observation using a SEM revealed that fresh red mud sample was amorphous while the 10-year-old red mud sample was fairly well crystallized. TGA results showed that the temperature at which the valley of weight loss occurred increased from 681.9℃ for fresh red mud to 722.9℃ for the 5-year-old red mud to 734.7℃ for the 10-year-old red mud. These results suggest that the contents of calcium carbonate increased with increasing storage time. Slow titration of the red mud samples with standardized acid solutions for two years indicated that the fresh red mud had an acid neutralizing capacity （ANC） of about 10 mol/kg while the ANC of old red mud samples was around 9 mol/kg. The ANC values obtained from the determination of BPC red mud here are much higher than those previously reported for red mud derived from the pure Bayer Process at the Queensland Alumina Limitd, Australia, and at the Pinggno Alumina Refinery, China.     

Nature of magmatism and sedimentation at a Columbia active margin: Insights from combined U–Pb and Lu–Hf isotope data of detrital zircons from NW India

Detrital zircons from a Palaeoproterozoic quartzite, deposited between 1.85 and 1.82 Ga in the northern Aravalli orogen of NW India, show a distinctive age peak of ca. 1.85 Ga and variable, but largely subchondritic εHf_{1.85 Ga} between ? 1.3 and ? 21.0 corresponding to hafnium model ages of 2.5 to 3.6 Ga. These data indicate an important period of reworking of ancient (Eo- to Neoarchaean), strongly heterogeneous continental crust at this time. Prevalence of ca. 1.85 Ga subduction-related granitoids, almost identical U–Pb age spectra and εHf_t of detrital zircons in ca. 1.85 Ga metasedimentary rocks in the Aravalli orogen and the inner Lesser Himalaya indicate similar sediment provenances and thus a geological connection between these two terranes during late Palaeoproterozoic. All together, the data constrain a rapid succession of sedimentation, metamorphism and subduction-related magmatic activity and support the interpretation of an active geodynamic realm along the entire north Indian margin at ca. 1.85 Ga. Comparison of detrital zircon data in conjunction with published paleomagnetic data from north India and other crustal blocks of the Columbia supercontinent, additionally, suggest a close affinity of north India with Madagascar, the Cathaysia block of South China and South Korea during Columbia times.     

Fingerprinting a multistage metamorphic fluid–rock history: Evidence from grain scale Sr,O and C isotopic and trace element variations in high-grade marbles from East Antarctica

Granulite grade marble layers interlayered with metapelitic granulites from Lützow Holm Bay, East Antarctica, provide insight into fluid–rock interactions during burial to and exhumation from lower crustal levels. Sub-millimeter scale strontium, oxygen and carbon isotope variations along with LA-ICPMS trace element geochemistry and mineral chemistry of texturally characterized carbonates and associated minerals helped to reconstruct the multistage metamorphic fluid history.Fluid–rock interaction dating back to prograde metamorphism are still preserved in consistently low oxygen and high strontium isotope compositions (δ¹⁸O = 12‰; ⁸⁷Sr/⁸⁶Sr_(550Ma) = 0.7248) within a massif dolomitic marble layer that escaped significant later metasomatism. In most marbles, total re-crystallization and isotopic resetting occurred in the presence of “externally derived” hyper-saline fluids that circulated along the carbonate layers during the early stages of prograde metamorphism. This leads to a trend of increased radiogenic Sr in marbles towards the value of associated metapelitic rocks that have ⁸⁷Sr/⁸⁶Sr_(550Ma) of 0.764.LA-ICPMS studies on trace elements in carbonate and associated silicate minerals at different textural settings, distinguished using cathodoluminescence microscopy, revealed multiple metasomatic events during retrograde metamorphism. Trace element contents of Ba, Sr, Pb and U gave compelling evidence for metasomatic alteration that postdate the exsolution of carbonate at ~ 600 ºC, which can be correlated with the fluids released from the crystallization of anatectic melts and pegmatites. Subsequently, meteoric fluid infiltration occurred at a shallower level of the crust and caused extreme oxygen isotopic heterogeneity (δ¹⁸O = 14.7 ~ ? 4.9‰) and imprinted high concentration of fluid mobile elements. Taken together our results emphasize the importance of integrating textural and chemical heterogeneities to reveal the multiple episodes of fluid–rock interaction processes in a dynamic continental crust, which has major implications on migration of fluids and material and help in formulating models on the geodynamic evolution of crust.     

Malayaite and tin‐bearing silicates from a skarn at Doradilla via Bourke,New South Wales

An extensive complex zoned skarn is developed at the contact of a leucoadamellite intrusive at Doradilla, NW New South Wales. The skarn is a disequilibrium assemblage resulting from a progressive sequence of replacement of a carbonate precursor. Early grossular‐clinopyroxene rocks are replaced by andradite with 0.5–3.5 wt.% SnO₂ clinopyroxene and quartz. Later alteration along fractures and bedding planes of the garnet‐clinopyroxene quartz assemblage has produced calcite‐malayaite (CaSn0.95Ti0.05SiO₅) veins. The final replacement stage was the overprinting of the silicate phases by assemblages containing sulphides, cassiterite, magnetite, titanite, fluorite, biotite and chlorite. The tin content of garent increases with increasing andradite component suggesting replacement of Fe³⁺ by Sn⁴⁺. Associated clinopyroxenes contain 0.1% SnO₂. The coexistence of titanite and its tin isomorph malayaite with extremely limited solid solution indicates late stage skarn temperatures of less than 400°C.