1,720,956 research outputs found
Decommissioned mining areas: an environmental issue or a source of critical raw materials? Insights from the Pb-Zn Raibl mining district (northeastern Italian Alps)
No full textThe demand for natural mineral resources has been rising in recent decades due to changes in the energy, ecological and digital disciplines. This requires a greater demand for extraction and production of critical raw materials (CRMs). Among the CRMs, the occurrence of metal(loid)s including potentially toxic elements (PTEs) such as lead (Pb), zinc (Zn), thallium
(Tl), arsenic (As), cadmium (Cd) and antimony (Sb) in the environment as the legacy of past mining activities is a well-known concern worldwide, posing a risk to water resources and human health (El Rasafi et al.,
2017). However, the occurrence of metal(loid)s may
also represent a resource since large amounts of mine
wastes (such as tailings ponds), which normally are the
major source of contamination for the surrounding
environment, can host valuable amounts of elements
of economic interest (Ceniceros-Gómez et al., 2018).
The extraction activity at the Raibl mining district (NE
Italian Alps) has been documented since 1320 A.D. In
its last years of operation, almost 350,000 tons of ore
(sphalerite and galena) were mined annually. The
Raibl mine was closed in 1991 as the deposits were no
longer considered economically viable. The Zn-Pb ore
deposit of Raibl includes sphalerite, galena, iron (Fe)
sulphides (pyrite and marcasite), and baryte as
primary minerals followed by Fe oxy-hydroxides,
smithsonite, hydrozincite and cerussite with dolomite
and calcite among gangue minerals.
Previous investigations on the area reported elevated
concentrations of metal(loid)s near mine waste heaps
(up to around or over 100 mg/kg for Tl, Sb, Cd, Ge; >
1,000 mg/kg for As; > 1% for Pb and > 10% for Zn and
Fe), which are made up of flotation tailings and waste
rocks scattered around the mining village and stored
in the tailings ponds. Moreover, the weathered tailings
showed a high potential as secondary source of Tl and
other PTEs in surface and groundwater, especially
during periods of high flow river conditions (Barago et
al., 2023).
Current ongoing research aims to evaluate the
occurrence of CRMs in the sludge accumulated in the
tailings impoundments following mineral processing
for the extraction of Pb and Zn during the mining
activity. Some boreholes were performed in the
tailings impoundments followed by in the field
analyses using portable X-Ray Fluorescence
Spectroscopy (pXRF), which is one of the main
geochemical analytical techniques employed in multielemental
screening for the management of
contaminated sites.
Electrical Resistivity Tomography (ERT) profiles were
executed to estimate the thickness of tailings and
evaluate potential correlations with detected metal
concentrations. This preliminary survey aided in the
collection of representative subsamples for further
geochemical characterisation by destructive standard
laboratory techniques and extraction procedures thus
allowing both to investigate the mobility of Tl and
other PTEs in solution as well as to identify volumes of
tailings that may represent a potential source of CRMs
Effects of groundwater and tailings interaction on the mobility of Thallium and other potentially toxic elements in a decommissioned Pb-Zn mining site (Raibl mine, north-eastern Italian Alps)
No full textMining activity at the Raibl district (northeastern Italian Alps) date back to 1320, reaching the peak production in the 20th century. Nearly 350,000 tons of lead-zinc (Pb- Zn) ore, primarily sphalerite (ZnS) and galena (PbS), were annually extracted during the last years of operation until the mine closure in 1991. The ore deposit also includes iron (Fe) sulfides (pyrite and marcasite), baryte, and secondary minerals such as Fe oxy-hydroxides, smithsonite, hydrozincite, and cerussite, with dolomite and calcite as gangue minerals.
Between 1976 and 1991, nearly 4 million tons of mine tailings, byproducts of the milling and flotation processes employed to extract the elements of economic interest, were accumulated in tailings ponds located nearby the Rio del Lago stream, the main watercourse in the area. These tailings are highly enriched in Zn, Pb, and Fe, as well as PTEs, including Thallium (Tl), and represent a secondary source of Tl and other PTEs in surface and groundwater, especially under conditions of heavy rainfall and high river flow (Barago et al., 2023). Moreover, the carbonate host rocks provide a buffering effect, leading to neutral mine drainage (NMD), despite ongoing sulphide oxidation.
Currently, the site is undergoing remediation, as concentrations of PTEs in surface and groundwater often exceed national regulatory limits. Specifically, Tl concentrations persist at levels one order of magnitude above the threshold limit (>2 μg L−1) downstream the mining district.
This study aims at assessing the interactions between groundwater and tailings accumulated in the impoundments which promotes the release of Tl and other PTEs in the dissolved phase. Boreholes were recently drilled in the tailings ponds, followed by on-site analyses using portable X-ray fluorescence spectroscopy (pXRF), a key geochemical technique for multi-elemental screening in contaminated sites (Barago et al., 2022). Subsequent sub-sampling of representative tailings levels allowed for a detailed characterisation of the material in the laboratory through inductively coupled plasma atomic emission and mass spectrometry (ICP-AES, ICP-MS). As expected, results con-firmed elevated concentrations of Zn (1.21 – 7.99 wt%), Pb (0.29 – 1.76 wt%), Fe (2.15 –14.2 wt%), As (505 – 2964 μg g-1), and Tl (65.8 – 677 μg g-1).
Based on this characterisation, tailings samples with high Tl concentrations (rang-ing from 185 and 677 μg g-1) were selected for further extraction and leaching tests to evaluate the geochemical behaviour of Tl and other PTEs as well as the processes con-trolling their release in solution. Gaining insights into these mechanisms is crucial for assessing the environmental impact of Tl contamination and developing effective strategies to mitigate its mobility, contributing to the protection of surrounding eco-systems and water resources.
ACKNOWLEDGEMENTS
The authors want to thank Claudio Ellero for his help during field and laboratory activities.
REFERENCES
Barago, N., Pavoni, E., Floreani, F., Crosera, M., Adami, G., Lenaz, D., Larese Filon, F., and Covelli, S., 2022. Portable X-ray Fluorescence (pXRF) as a Tool for Environmental Characterisation and Man-agement of Mining Wastes: Benefits and Limits. Applied Sciences, v.12, 12189.
Barago, N., Pavoni, E., Floreani, F., Crosera, M., Adami, G., Lenaz, D., and Covelli, S., 2023. Hydrogeo-chemistry of thallium and other potentially toxic elements in neutral mine drainage at the decom-missioned Pb-Zn Raibl mine (Eastern Alps, Italy). Journal of Geochemical Exploration, v.245, 107129
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
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koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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