46 research outputs found

    Magmatic and hydrothermal behavior of uranium in syntectonic leucogranites: The uranium mineralization associated with the Hercynian Guérande granite (Armorican Massif, France)

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    Most of the hydrothermal uranium (U) deposits from the European Hercynian belt (EHB) are spatially associated with Carboniferous peraluminous leucogranites. In the southern part of the Armorican Massif (French part of the EHB), the GuĂ©rande peraluminous leucogranite was emplaced in an extensional deformation zone at ca. 310 Ma and is spatially associated with several U deposits and occurrences. The apical zone of the intrusion is structurally located below the Pen Ar Ran U deposit, a perigranitic vein-type deposit where mineralization occurs at the contact between black shales and Ordovician acid metavolcanics. In the MĂ©tairie-Neuve intragranitic deposit, uranium oxide-quartz veins crosscut the granite and a metasedimentary enclave. Airborne radiometric data and published trace element analyses on the GuĂ©rande leucogranite suggest significant uranium leaching at the apical zone of the intrusion. The primary U enrichment in the apical zone of the granite likely occurred during both fractional crystallization and the interaction with magmatic fluids. The low Th/U values (18Owhole rock = 9.7–11.6‰ for deformed samples and ÎŽ18Owhole rock = 12.2–13.6‰ for other samples) indicate that the deformed facies of the apical zone underwent sub-solidus alteration at depth with oxidizing meteoric fluids. Fluid inclusion analyses on a quartz comb from a uranium oxide-quartz vein of the Pen Ar Ran deposit show evidence of low-salinity fluids (1–6 wt.% NaCl eq.), in good agreement with the contribution of meteoric fluids. Fluid trapping temperatures in the range of 250–350 °C suggest an elevated geothermal gradient, probably related to regional extension and the occurrence of magmatic activity in the environment close to the deposit at the time of its formation. U-Pb dating on uranium oxides from the Pen Ar Ran and MĂ©tairie-Neuve deposits reveals three different mineralizing events. The first event at 296.6 ± 2.6 Ma (Pen Ar Ran) is sub-synchronous with hydrothermal circulations and the emplacement of late leucogranitic dykes in the GuĂ©rande leucogranite. The two last mineralizing events occur at 286.6 ± 1.0 Ma (MĂ©tairie-Neuve) and 274.6 ± 0.9 Ma (Pen Ar Ran), respectively. Backscattered uranium oxide imaging combined with major elements and REE geochemistry suggest similar conditions of mineralization during the two Pen Ar Ran mineralizing events at ca. 300 Ma and ca. 275 Ma, arguing for different hydrothermal circulation phases in the granite and deposits. Apatite fission track dating reveals that the GuĂ©rande granite was still at depth and above 120 °C when these mineralizing events occurred, in agreement with the results obtained on fluid inclusions at Pen Ar Ran. Based on this comprehensive data set, we propose that the GuĂ©rande leucogranite is the main source for uranium in the Pen Ar Ran and MĂ©tairie-Neuve deposits. Sub-solidus alteration via surface-derived low-salinity oxidizing fluids likely promoted uranium leaching from magmatic uranium oxides within the leucogranite. The leached out uranium may then have been precipitated in the reducing environment represented by the surrounding black shales or graphitic quartzites. As similar mineralizing events occurred subsequently until ca. 275 Ma, meteoric oxidizing fluids likely percolated during the time when the GuĂ©rande leucogranite was still at depth. The age of the U mineralizing events in the GuĂ©rande region (300–275 Ma) is consistent with that obtained on other U deposits in the EHB and could suggest a similar mineralization condition, with long-term upper to middle crustal infiltration of meteoric fluids likely to have mobilized U from fertile peraluminous leucogranites during the Late Carboniferous to Permian crustal extension events

    Leaky doors: private captivity as a prominent source of bird introductions in Australia

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    The international pet trade is a major source of emerging invasive vertebrate species. We used online resources as a novel source of information for accidental bird escapes, and we investigated the factors that influence the frequency and distribution of bird escapes at a continental scale. We collected information on over 5,000 pet birds reported to be missing on animal websites during the last 15 years in Australia. We investigated whether variables linked to pet ownership successfully predicted bird escapes, and we assessed the potential distribution of these escapes. Most of the reported birds were parrots (> 90%), thus, we analysed factors associated with the frequency of parrot escapes. We found that bird escapes in Australia are much more frequent than previously acknowledged. Bird escapes were reported more frequently within, or around, large Australian capital cities. Socio-economic factors, such as the average personal income level of the community, and the level of human modification to the environment were the best predictors of bird escapes. Cheaper parrot species, Australian natives, and parrot species regarded as peaceful or playful were the most frequently reported escapees. Accidental introductions have been overlooked as an important source of animal incursions. Information on bird escapes is available online in many higher income countries and, in Australia, this is particularly apparent for parrot species. We believe that online resources may provide useful tools for passive surveillance for non-native pet species. Online surveillance will be particularly relevant for species that are highly reported, such as parrots, and species that are either valuable or highly commensal.Miquel Vall-llosera, Phillip Casse

    The importance of the exposome and allostatic load in the planetary health paradigm

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    In 1980, Jonas Salk (1914-1995) encouraged professionals in anthropology and related disciplines to consider the interconnections between "planetary health," sociocultural changes associated with technological advances, and the biology of human health. The concept of planetary health emphasizes that human health is intricately connected to the health of natural systems within the Earth's biosphere; experts in physiological anthropology have illuminated some of the mechanisms by which experiences in natural environments (or the built environment) can promote or detract from health. For example, shinrin-yoku and related research (which first emerged from Japan in the 1990s) helped set in motion international studies that have since examined physiological responses to time spent in natural and/or urban environments. However, in order to advance such findings into planetary health discourse, it will be necessary to further understand how these biological responses (inflammation and the collective of allostatic load) are connected to psychological constructs such as nature relatedness, and pro-social/environmental attitudes and behaviors. The exposome refers to total environmental exposures-detrimental and beneficial-that can help predict biological responses of the organism to environment over time. Advances in "omics" techniques-metagenomics, proteomics, metabolomics-and systems biology are allowing researchers to gain unprecedented insight into the physiological ramifications of human behavior. Objective markers of stress physiology and microbiome research may help illuminate the personal, public, and planetary health consequences of "extinction of experience." At the same time, planetary health as an emerging multidisciplinary concept will be strengthened by input from the perspectives of physiological anthropology.Peer reviewe

    Birds in the playground: Evaluating the effectiveness of an urban environmental education project in enhancing school children's awareness, knowledge and attitudes towards local wildlife.

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    Children nowadays, particularly in urban areas, are more disconnected from nature than ever before, leading to a large-scale "extinction of experience" with the natural world. Yet there are many potential benefits from children interacting with nature first-hand, including via outdoor learning opportunities. Urban environmental education programmes typically aim to increase awareness and knowledge of local biodiversity and to promote positive attitudes and behaviour towards the environment. However, limited research has been conducted evaluating to what extent these interventions achieve their goals. Here, we explore and assess the influence of a six-week bird-feeding and monitoring project conducted within school grounds ("Bird Buddies") on individual awareness, knowledge and attitudes towards birds by primary school children. This initiative was conducted across eight (sub-)urban primary schools within Brighton and Hove (UK), with 220 participating children (aged 7 to 10). Via pre- and post-project questionnaires, we found evidence for enhanced awareness of local biodiversity, alongside significant gains in both bird identification knowledge and attitudes, which were greatest for children with little prior exposure to nature. Many children expressed a keenness to continue improving the environmental value of their school grounds and to apply elements of the project at home. Student project evaluation scores were consistently positive. Mirroring this, participating teachers endorsed the project as a positive learning experience for their students. One year after the project, several schools were continuing to feed and watch birds. Collectively, the findings from this study highlight the multiple benefits that can be derived from engagement with a relatively short outdoor environmental activity. We therefore believe that such interventions, if repeated locally/longer term, could enhance children's experience with nature in urban settings with combined positive environmental impact

    Schoolchildren and one of the most unpopular animals: are they ready to protect snakes?

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    For cultural reasons and due to the narrow vision of environmental policy makers, most conservation efforts focus on a few charismatic species and consequently neglect the ma- jority of others under threat; many unpopular species are even killed in large numbers with little con- cern. Redressing this bias through educational programs is therefore important. Snakes are unpopular animals; they suffer from human harassment in most places and many populations have declined worldwide. Consequently, they provide suitable substrate to better improve conservation education in schoolchildren. Responses to a questionnaire administered to 2,570 schoolchildren (7–14 years old) from 10 countries showed that many children liked snakes and that most of the students wanted to see snakes protected. Such counterintuitive results were supported by the explanations given by the children, notably the reasons they liked or disliked snakes. Previous physical contact with snakes was often associated with snake likeability. We also found strong and expected differences between countries: for instance, where venomous snakes represented a health risk, most children declared to be afraid of snakes. Overall, our results negate the simplistic, and previously unverified, adult view that snakes are necessarily perceived as frightening animals, thereby justifying their persecution. This study provides an encouraging message, suggesting that it is not compulsory to focus on charismatic animals to convince children to protect wildlife

    Meteoric fluid‐rock interaction in Variscan shear zones

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    International audienceVariscan shear zones in the Armorican Massif represent sites of strong fluid‐rock interaction. The hydrogen isotope composition of muscovite (ήDMs) from syntectonic leucogranite allows to determine the source of fluids that infiltrated the footwall of three detachment zones and the South Armorican Shear Zone. Using temperatures of hydrogen isotope exchange estimated from microstructural data, we calculate the hydrogen isotope ratios of water (ήDwater) present within the shear zones during high‐temperature deformation. A ~40‰ difference in ήDwater values from deep to shallow crustal level reveals a mixing relationship between deep crustal fluids with higher ήD values that range from −34 to −33‰, and meteoric fluids with ήD values as low as −74‰ in the upper part of detachment footwalls

    Factors Influencing Schoolchildren's Responses to a Questionnaire in Wildlife Conservation Education

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    Questionnaires are important tools for assessing attitudes regarding conservation issues. However, they are not easily comparable and their reliability has been insufficiently assessed. We examined factors influencing responses to open- and closed-ended questions about animal conservation to more than 600 schoolchildren (9 years old on average). We analysed the level of understanding, controllable (e.g. sample size) and less controllable factors (e.g. affectivity). Most children responded appropriately to the questions, but subtle changes in the phrasing influenced the answers. Affectivity towards endearing species and spontaneity also influenced the responses whereas small sample sizes (50 children) provided relatively stable patterns. Overall, we suggest that standardization of questionnaires administered over large spatial and time scales is needed to accurately assess children’s attitudes towards conservation issues
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