1,720,977 research outputs found
Environmental concerns and future perspectives related to the legacy of metal(loid) contamination in the vicinity of a dismissed Pb-Zn mining area (Raibl, NE Italy)
No full textThe occurrence of relevant amounts of potential toxic elements (PTEs) in the environment as a legacy of past extraction and metallurgical activities at decommissioned mining areas represents a worldwide concern, potentially posing a threat to ecosystems and human health. This aspect is strongly dependent on the mobility and bioavailability of PTEs once released in the environment (Favas et al., 2011). However, in addition to being sources of contamination, mine waste such as tailings ponds can potentially be a resource since they may still host notable amounts of various elements of economic interest such as those included in European Union’s list of Critical Raw Materials (CRMs) (Rosario-Beltré et al., 2023).
This study is focused on the assessment of metal(loid) distribution and environmental impact related to past extraction activities on the soils at the Pb-Zn Raibl mining district (NE Italy), which ended in 1991. Concentrations of several PTEs (As, Cd, Fe, Pb, Tl, Zn) and CRMs (As, Ge, Mn, Sb) were determined on sub-surface samples of various solid matrices (soils, waste rocks, tailings) collected throughout the mining district. A single-step extraction with 0.5 M HCl solution was used to evaluate the labile fraction of PTEs, potentially more mobile and bioavailable in the environment.
As expected, mine waste heaps, consisting of waste rocks and flotation tailings stored in tailings impoundments and scattered within the mining district, showed high concentrations of metal(loid)s (≤ 100 mg/kg for Sb, Cd and Ge; > 500 mg/kg for Tl and Mn; > 1,000 mg/kg for As; > 1 wt% for Zn; > 10 wt% for Fe and Zn). Notably low concentrations were found in samples collected upstream the former mine, which are considered representative of the natural background of the study area. Overall, the leachable metal(loid)s concentrations are well correlated with the total content, with the highest PTEs (i.e. Zn, Pb, Fe, Cd) values generally observed in unprocessed waste rock samples. The only exception is represented by Tl which showed the highest labile concentration in tailings (up to 255 mg/kg), confirming their potential impact on local water resources (Barago et al., 2023). However, the highest percentages of the metal(loid)s leachable fraction were generally found for soils with a greater organic matter (OM) content, due to the lower pH and the potential formation of soluble organometallic complexes during soil ageing. Considering that remediation of the en-tire area is not feasible due to the extension of the contamination, this potential in-creased in the mobility of PTEs as soil ages should be considered when evaluating appropriate management strategies aimed at limiting PTEs dispersion and impact on local ecosystems. These strategies may also include the reprocessing of mine wastes accumulated in tailings ponds, which could both reduce the risk to water resources and human health and to recover critical or strategic elements such as As or Ge. Fur-ther research is still ongoing with the aim of broadening knowledge on the residual content in CRMs and PTEs buried in tailings ponds and providing data to assess the feasibility of this approach.
REFERENCES
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, 245, 107129.
Favas, P.J.C., Pratas, J., Gomes, M.E.P., and Cala, V., 2011. Selective chemical extraction of heavy metals in tailings and soils contaminated by mining activity: environmental implications. Journal of Geo-chemical Exploration, 111, 160-171.
Rosario-Beltré, A.J., Sánchez-España, J., Rodríguez-Gómez, V., Fernández-Naranjo, F.J., Bellido-Martín, E., Adánez-Sanjuán, P., and Arranz-González J.C., 2023. Critical raw materials recovery potential from Spanish mine wastes: a national-scale preliminary assessment. Journal of Cleaner Production, 407, 137163
Evasion of Gaseous Elemental Mercury from Forest and Urban Soils Contaminated by Historical and Modern Ore Roasting Processes (Idrija, Slovenia)
Full text linkConsiderable amounts of gaseous elemental mercury (Hg-0) can be released into the atmosphere from Hg-enriched substrates, such as those from former mining areas, posing a potential environmental threat. In this work, Hg-0 fluxes at the soil-air interface under natural vegetation covers were measured in various locations within the Idrija Hg mining area (Slovenia) and its surroundings. Sites were selected in order to compare Hg-0 fluxes from both forest soils heavily impacted by historical ore roasting and urban soils characterised by a different degree of Hg enrichment due to the natural occurrence of Hg in rocks or recent mining and roasting processes. Replicate measurements at each site were conducted using a non-steady state flux chamber coupled with a real-time Hg-0 analyser (Lumex RA-915M). Moreover, topsoil samples (0-2 cm) were analysed for Hg total concentration and speciation. Cinnabar was the predominant Hg form in almost all the sites. Despite Hg-0 being undetectable in soils using thermo-desorption, substantial emissions were observed (70.7-701.8 ng m(-2) h(-1)). Urban soils in a naturally enriched area showed on average the highest Hg-0 fluxes, whereas relatively low emissions were found at the historical roasting site, which is currently forested, despite the significantly high total Hg content in soils (up to 219.0 and 10,400 mg kg(-1), respectively). Overall, our findings confirm that shading by trees or litter may effectively limit the amount of Hg-0 released into the atmosphere even from extremely enriched soils, thus acting as a natural mitigation
Knowledge management system requirements to support Engineering-To-Order manufacturing of SMEs
No full textThis paper analyses the characteristics of a knowledge management system supporting an Engineer-To-Order manufacturing strategy in the context of small and medium-sized enterprises (SMEs). For this reason, after the identification of a set of knowledge management system requirements, three in-depth case studies of Italian small and medium-sized enterprises are discussed. The paper introduces an IT-based tool to support implementing a knowledge management system to enhance Engineer-To-Order manufacturing performance. The paper contributes to advancing the understanding of knowledge management systems’ relevance to improve SMEs’ performance, specifically in the operative context of the Engineer-To-Order business and provides practical implications for IT-based tools defining a platform for the development of knowledge management systems
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
Gaseous mercury emissions from forest and urban soils heavily impacted by past mining in the Idrija mining district (Slovenia)
No full textThe historical mining and ore roasting activities lasted for about 500 years at Idrija (Slovenia), the second largest mercury (Hg) mine worldwide, have caused a widespread contamination of the surrounding environments through direct losses and discharges of residues and atmospheric depositions (Gosar & Teršič, 2012). Substrate enriched in Hg can release notable amounts of gaseous elemental mercury (GEM) into the atmosphere (Agnan et al., 2016), potentially contributing to widen the spatial distribution of this metal and to
increase the exposure to Hg of inhabitants through inhalation.
This study is focused on the evaluation of GEM fluxes at the soil-air interface within both the urban area of Idrija and its surroundings. Site selection was aimed at comparing emissions from substrates subject to different Hg supplies. The selected urban soils were characterised by different degree of Hg enrichment due to its natural occurrence in underlying bedrock or variable atmospheric depositions related to ore roasting in modern furnaces. In addition, GEM fluxes were measured at an ancient roasting site in the forests surrounding Idrija subject to considerable Hg supplies during ore processing in XVI-XVII centuries. Measurements were performed during the summer season, the most favourable for GEM evasion (Floreani et al., 2023).
A non-steady state flux chamber coupled with a real-time GEM analyser was used to evaluate fluxes from soils with the natural vegetation cover performing replicate measurements at each site. Topsoil Hg content and speciation were also assessed through thermo-desorption technique.
Overall, GEM fluxes observed from undisturbed soils ranged between 70.7 and 702 ng m-2 h-1 with the highest average value obtained for the natural enriched site at Idrija. The spatial variability of fluxes was mainly related to total Hg content in soils. However, a more developed herbaceous vegetation may limit GEM releases at the atmospherically influenced site near the most recent furnace despite the greater availability of Hg bound to organic matter, which is potentially more available for reduction to GEM and evasion. This is especially evident considering the low fluxes observed at the forested ancient roasting site despite the extremely high Hg concentrations in soils (up to 10,400 mg kg-1).
Results from this study highlight that shading by vegetation can significantly limit GEM re-emission to the atmosphere even in extremely contaminated areas. However, a significantly high flux (2466 ng m-2 h-1) was recorded at the ancient roasting site on a bare soil surface under an uprooted tree, suggesting that care should be taken in forest management practices to avoid potential strong re-emission of GEM related to direct exposure of these heavily contaminated soils to solar radiation
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
sophisticated methods
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