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Although approximately half of global lithium consumption is used in the rechargeable battery industry, lithium is also in demand for other specialized applications, such as high-temperature lubricants, ceramics, glass, and pharmaceuticals. The growing need for efficient lithium recovery and recycling underscores the importance of fast and accurate analytical tools for determining lithium concentrations in non-compliant and waste materials generated by industrial processes. In this paper, we present a machine learning-based procedure utilizing Laser-Induced Breakdown Spectroscopy (LIBS) to accurately quantify lithium concentrations in lithium-rich non-compliant materials derived from the industrial production of enamels used for coating metallic surfaces. This procedure addresses challenges such as strong self-absorption and matrix effects, which limit the effectiveness of conventional univariate calibration methods. By employing a multivariate approach, we developed a single model capable of quantifying lithium content across a wide concentration range. A comparison of the LIBS results with those obtained using conventional laboratory analysis (Inductively Coupled Plasma–Optical Emission Spectrometry, ICP-OES) confirms that LIBS can deliver the speed, precision, and reliability required for potential routine applications in the lithium recovery and recycling industry.

PurposeThe extensive Hg contamination in soil and sediments occurring along the Paglia River (Central Italy) is the result of the interplay between the geomorphological changes of the river and anthropic activities, primarily associated to the exploitation of Hg-deposits in \"The Monte Amiata mining district\" (MAMD). The present study determines the implications of the morphological changes that occurred along the Paglia River in the last 200 years on the distribution of Hg along the floodplain and riverbed, which today represent one of the main Hg-reservoirs in the MAMD.Materials and methodsThe temporal changes of the Paglia riverbed and the extent of its alluvial deposits were reconstructed by a GIS-based analysis of the available maps and aerial photos. The Hg-concentration in soil and sediment samples, collected along five transects transverse to the Paglia River channel, was determined by ICP-MS.Results and discussionSamples along the investigated Paglia River segment typically show Hg-contents exceeding the Italian threshold for residential and public green soil use (1 mg kg−1). The distribution of Hg in the Paglia floodplain results from the combination of exceedance of sediment yield to the river during mining activities, that fed the floodplain with large amounts of Hg-contaminated sediments during its braided stage about 100 years ago, and the morphological changes of the river, that led to the evolution from a braided to the present-day single channel river. The magnitude of the extension of Hg-contamination, the river geomorphologic changes, and the processes of transport, deposition, and re-suspension did not allow a natural “clean up” of the river system, which shows a low resilience. Under high flow conditions, and especially in coincidence with intense rain events, large amounts of Hg stored in the overbank sediments are mobilized and redistributed, contributing to make the floodplain a secondary Hg-source. Extreme weather events, expected to intensify as a consequence of climate change, will contribute to the recurrent distribution of Hg-contaminated legacy sediments in the floodplain and along the Paglia river course.ConclusionFrom a water/land management perspective, the variability of the river flow, associated with an increase of extreme flood events driven by climate change, will affect the distribution of Hg-contaminated particles in the Paglia River, contributing to the Hg input into the Mediterranean Sea in the future.

Previous studies documented the contribution of toxic elements (Hg, As, and Sb) from the dismissed Monte Amiata Mining District (Italy), the third largest Hg producer worldwide, to the Mediterranean Sea. Another highly toxic element, thallium (Tl), received less attention. Here we report a reconnaissance study of the spatial variability of Tl content in stream sediments across the Fiora River catchment, which drains part of the Hg and Sb mining districts. Thallium contents are comparatively low (≤0.4 mg/kg) in sediments of creeks directly draining the mining areas, whereas they increase up to 2 mg/kg in the catchment section that drains the Vulsini ultrapotassic volcanic province, where no known mineral deposits occur. Results suggest that Hg and Sb deposits cannot be the only Tl source in the catchment. The most likely alternative/additional candidate are the high-K volcanic rocks. Although no specific data for the Vulsini district exist, a distinct Tl geochemical anomaly linked to the Latium volcanic province is present. The total Tl mass contained in sediments discharged yearly into the Mediterranean Sea from the Fiora River is estimated in the order of 0.1 t. This reconnaissance study indicates a non-negligible potential release of Tl from the mining districts and volcanic catchments in Central Italy and suggests the opportunity of further investigation on Tl distribution and speciation in the area.

The iron-oxide-copper-gold (IOCG) skarns of the Tatatila-Las Minas mining district in central Mexico represent a structurally-controlled, exhumed fossil geothermal system located in the eastern sector of the Trans-Mexican Volcanic Belt (TMVB). The district was historically exploited for gold and copper mineralization. The emplacement of the ore bodies was controlled by regional Neogene–Quaternary NE- and NW-striking fault systems formed during the extensional evolution of the TMVB. These faults acted as conduits for high-temperature hydrothermal fluids circulating during the cooling of the Neogene magmatic intrusions. By integrating detailed field study with available exploration borehole data, the spatial distribution of the skarn bodies was reconstructed. Three main emplacement geometries were identified: (a) at contacts between magmatic bodies and host rocks, (b) as lenticular or irregular bodies parallel to the host rock foliation, and (c) at the intersections of near-orthogonal faults. Although structural controls on skarn formation represent a key factor in ore emplacement, their analysis remains scarcely explored. This paper therefore contributes to filling this gap by providing a detailed characterization of the structural framework governing IOCG skarn development at Tatatila–Las Minas. The results improve understanding of IOCG systems formation and provide predictive criteria for mineral exploration in similar geological settings, potentially reducing exploration and mining risks.

The Mediterranean Sea is characterized by a marked mercury (Hg) geochemical anomaly, arising in part from large Hg deposits. Mercury mass loads discharged from the Monte Amiata mining district (Central Italy) to the Mediterranean Sea through the Paglia–Tiber River system were estimated. Data from two seasons showed that up to 40 kg year−1 of Hg are drained to Tiber River and finally to the Mediterranean Sea. The mercury mass loads varied in different seasons, from 3 mg day−1 in the upper section of Paglia River in November to 42 g day−1 before the confluence with Tiber River in June. Along Tiber River, up to 15 ng L−1 of the total Hg found at a site after Rome showed that Hg can be discharged to the sea. The Alviano reservoir along Tiber River acts as a temporary trap for Hg-rich particulate, while dam operations may promote Hg release (up to 223 g day−1). The combination of hydrologic factors controlling Hg transport, the torrential regime in the upper catchment of Paglia River, the waterway steepness, together with Hg-contaminated legacy sediments in the Paglia River floodplain, make the Paglia–Tiber River system a long-lasting intermittent source of Hg to Tiber River and the Mediterranean Sea.

Biomonitoring is a widely employed approach to track changes in the environment. Its use to assess the impact of geothermal energy exploitation for power production is comparatively minor, and largely referred to Tuscany, Italy, geothermal fields. Most examples describe impacts on vegetation, particularly lichens. Biomonitoring proved useful as a tool to reveal the distribution of specific contaminants (e.g., mercury and H 2 S), and as an overall indicator of the impact on ecosystems. In consideration of the comparatively low cost/benefit ratio, the use of biomonitoring should be encouraged. In particular, it could prove useful to establish the natural background prior to development of geothermal exploitation, and to document any subsequent change.

The terrestrial environment is an important contributor of microplastics (MPs) to the oceans. Urban streams, strictly interwoven in the city network and to the MPs’ terrestrial source, have a relevant impact on the MP budget of large rivers and, in turn, marine areas. We investigated the fluxes (items/day) of MPs and natural fibers of Mugnone Creek, a small stream crossing the highly urbanized landscape of Florence (Italy) and ending in the Arno River (and eventually to the Tyrrhenian Sea). Measurements were done in dry and wet seasons for two years (2019–2020); stream sediments were also collected in 2019. The highest loads of anthropogenic particles were observed in the 2019 wet season (109 items/day) at the creek outlet. The number of items in sediments increased from upstream (500 items/kg) to urban sites (1540 items/kg). Fibers were the dominant shape class; they were mostly cellulosic in composition. Among synthetic items, fragments of butadiene-styrene (SBR), indicative of tire wear, were observed. Domestic wastewater discharge and vehicular traffic are important sources of pollution for Mugnone Creek, especially during rain events. The study of small creeks is of pivotal importance to limit the availability of MPs in the environment.

Trees may represent useful long-term monitors of historical trends of atmospheric pollution due to the trace elements stored along the tree rings caused by modifications in the environment during a tree’s life. Chestnut (Castanea sativa Mill.) tree trunk sections were used to document the yearly evolution of atmospheric Hg in the world-class mining district of Monte Amiata (MAMD; Central Italy) and were exploited until 1982. An additional source of Hg emissions in the area have been the active geothermal power plants. A marked decrease (from >200 µg/kg to <100 µg/kg) in Hg contents in heartwood tree rings is recorded, likely because of mine closure; the average contents (tens of µg/kg) in recent years remain higher than in a reference area ~150 km away from the district (average 4.6 µg/kg). Chestnut barks, recording present-day Hg pollution, systematically show higher Hg concentrations than sapwood (up to 394 µg/kg in the mining area). This study shows that tree rings may be a good record of the atmospheric Hg changes in areas affected by mining activity and geothermal plants and can be used as a low-cost biomonitoring method for impact minimization and optimal resource and land management.

In the present study, mercury (Hg) concentrations were investigated in lichens (Flavoparmelia caperata (L.) Hale, Parmelia saxatilis (L.) Ach., and Xanthoria parietina (L.) Th.Fr.) collected in the surrounding of the dismissed Abbadia San Salvatore Hg mine (Monte Amiata district, Italy). Results were integrated with Hg concentrations in tree barks and literature data of gaseous Hg levels determined by passive air samplers (PASs) in the same area. The ultimate goal was to compare results obtained by the three monitoring techniques to evaluate potential mismatches. Lichens displayed 180–3600 ng/g Hg, and Hg concentrations decreased exponentially with distance from the mine. Mercury concentration was lower than in Pinus nigra barks at the same site. There was a moderate correlation between Hg in lichen and Hg in bark, suggesting similar mechanisms of Hg uptake and residence times. However, correlation with published gaseous Hg concentrations (PASs) was moderate at best (Kendall Tau = 0.4–0.5, p > 0.05). The differences occurred because a) PASs collected gaseous Hg, whereas lichens and barks also picked up particulate Hg, and b) lichens and bark had a dynamic exchange with the atmosphere. Lichen, bark, and PAS outline different and complementary aspects of airborne Hg content and efficient monitoring programs in contaminated areas would benefit from the integration of data from different techniques.

Southern Tuscany (Italy) hosts geothermal anomalies with associated widespread CO 2 gas-rich manifestations and active travertine-deposing thermal springs. Geothermal anomalies have been active since the Late Miocene and have led to the formation of widespread Late Miocene–Pleistocene travertine deposits and meso- and epithermal mineralizations. This study investigates the travertine deposit exposed in the Castelnuovo dell’Abate area of southern Tuscany. Here, a fissure-ridge type travertine deposit and its feeding conduits, currently filled with banded calcite veins (i.e. banded travertine), represent a spectacular example of fossil hydrothermal circulation in the peripheral area of the exploited Monte Amiata geothermal field. The Castelnuovo dell’Abate travertine deposit and associated calcite veins were analysed to establish the characteristics of the parent hydrothermal fluids, and the age of this circulation. The focus of the study was on fluid inclusions, rarely considered in travertine studies, but able to provide direct information on the physico-chemical characteristics of the original fluid. Uranium–thorium geochronological data provided further constraints on the: (1) age of tectonic activity; (2) age of the hydrothermal circulation; and (3) evolution of the Monte Amiata geothermal anomaly. Results indicate that brittle deformation (NW- and SE-trending normal to oblique-slip faults) was active during at least the Middle Pleistocene and controlled a hydrothermal circulation mainly characterized by fluids of meteoric origin, and as old as 300–350 ka. This is the oldest circulation documented to date in the Monte Amiata area. The fluid chemical composition is comparable to that of fluids currently exploited in the shallow reservoir of the Monte Amiata geothermal field, therefore suggesting that fluid composition has not changed substantially over time. These fluids, however, have cooled by about 70 °C in the last 300–350 ka, corresponding to a cooling rate of the Monte Amiata geothermal area of about 20 °C 100 ka −1 .