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Melts with rhyolite compositions originate from partial melting of crustal rocks or extensive differentiation of basaltic melts, at temperatures in the range of 800 °C. Accordingly, they are confined to the shallow continental crust. Nevertheless, experimental studies have demonstrated that dacite-rhyolite melts can be generated at higher temperature (> 1000°c) and pressure (>2 GPa), by partial melting of continental crustal lithotypes, but direct evidence for their occurrence has never been found. This implies that rhyolite melts may be produced at mantle conditions either by subduction of sedimentary material or exhumation of subducted continental crust.Ephemeral rhyolite melt inclusions were found preserved in peridotite xenoliths from Tallante (Betic Cordillera, southern Spain) that are remnants of a supra-subduction mantle wedge. Here, the interaction of silica-rich melts with peridotite generated hybrid mantle domains, characterized by the occurrence of millimetre-sizes felsic veins with crust-like Sr-Nd-Pb-O- isotope compositions. The “Tallante” composite xenoliths were found among a wide population of peridotitic xenoliths, and display extreme compositional and isotopic heterogeneities both within the ambient peridotite and within the felsic veins. The latter consist of orthopyroxene, plagioclase, and quartz, and they are separated from the surrounding peridotite by an orthopyroxene-rich reaction zone. In their mineral phases, rhyolite glass inclusions and interstitial films associated to quartz crystals were observed. Petrological evidence and thermodynamic modelling indicate that rhyolite melts were originated by partial melting of near an-hydrous garnet-bearing metapelites at temperatures above 1000 °C. Partial melting was likely triggered by near-isothermal decompression during rapid exhumation of previously subducted crustal slivers. The melts reacted with the ambient lithospheric mantle at lower temperature (900 °C) and produced orthopyroxene, followed by plagioclase, quartz, and phlogopite. On the basis of chemical characteristics, it is hypothesized that potassic (HK-calc-alkalic to shoshonitic) and ultrapotassic magmas may originate from metasomatic mantle sources generated from the interaction of crustal rhyolitic melts with mantle peridotite.

Sulfur (S) is one of the key volatiles in Earth’s chemical cycles as it affects biological, climate, ore-deposits, and redox processes. It is known that S stored in the crust is recycled into the mantle at subduction zones. However, some aspects of the S cycle in the deep Earth such as S speciation, flux, and isotope composition and fractionation processes still remain unclear. Most of the S isotopic studies investigate the melt inclusions, which potentially preserve the original budget and isotopic signature of the magma. However, these researches are limited, as melt inclusions are rare. Studying ophiolites represent a valid alternative to investigate contents and isotopic features of S with the aim to reconstruct its cycle in different geodynamic settings. Ophiolites are fragments of ancient oceanic lithosphere that were tectonically emplaced into orogenic belts and, according to the Dilek and Furnes (2014) classification, they can be discriminated as subduction-unrelated and subduction-related magmatic rocks. In this work we compiled a global dataset of both subduction-unrelated and subduction-related ophiolitic basalts, and we measured their whole rock S contents and the relative S isotopic ratio (34S/32S) through using an elemental analyzer coupled with a mass spectrometer (EA-IRMS). The considered samples are Mid-Ocean Ridge Basalts (MORBs) from Corsica, Romania, Albania, and North Macedonia; ii) Island Arc Tholeiites (IAT) from Albania and Greece; iii) Calc-Alkaline Basalts (CAB) from Greece, Romania, North Macedonia, and Iran already constrained from a petrological and geochemical point of view by different studies (Moberly et al., 2006; Saccani et al., 2011; Brombin et al., 2022). In the studied basalts, the S contents range from 200 and 300 ppm. Despite the different areas of provenance, for most of the samples the S isotopic signatures are similar in rocks having similar geochemical affinity. The average S isotopic ratios are –0.7‰, +5.8, and +7.4‰, for MORBs, IATs, and CABs, respectively. It is evident that only MORBs preserved the typical S signature of the Earth mantle (i.e., from –2‰ to 0‰). The subduction related magmatic rocks (i.e., IATs and CABs) show positive S isotopic values, probably due to the contamination of i) enriched-34S subducting sediments in the magma sources or ii) fluids released by serpentinized rocks of the slab, which typically have comparatively more positive S signature.In summary, this work allowed the definition of: i) the S isotope compositions in both subduction-unrelated and subduction-related magmatic rocks; ii) the possible causes which modify the original S signature (e.g., contamination by subducting sediments). This research is therefore essential to understand the global S cycle. ReferencesDilek Y., Furnes H., 2014. Elements, 10: 93-100.Moberly R., et al., 2006. Proc. ODP, Sci. Results, 203: 1-36.Saccani E., et al., 2011. Lithos, 124: 227-242.Brombin V., et al., 2022. Ofioliti, 47: 85-102.

Geochemical investigations of agricultural soils are fundamental to characterize pedosphere dynamics that sustain ecosystem services linked with agriculture. Parameters like soil moisture, soil organic matter (SOM), and soil organic carbon (SOC) are strong instruments to evaluate carbon sink potential.Satellite Earth Observation is a significant source of free data that can be linked to soil characteristics and dynamics and employed to produce temporal series. Access to these data is nowadays facilitated by platforms such as ADAM (https://adamplatform.eu), which allow users to quickly search for, visualize and subset data products, greatly reducing the volume of data that end users must handle.In this work we demonstrate the usefulness of such systems by carrying out a geochemical investigation of 100 superficial (0-15 cm) soil samples collected in the province of Ferrara (North-Eastern Italy) and using the ADAM platform to associate to each a time series of Sentinel 2 data. The samples were collected in October 2021 in fields that were ploughed or mono-cultivated at maize, soybean, rice, and winter vegetables. To obtain the average soil properties over a spatial scale larger than the satellite sensor resolution, we adopted a composite sampling strategy, merging 5 sub-samples collected at the vertexes and at the center of a 30x30 m2 area. Soil granulometry was recognized from clay to medium sand, with exception of peat deposits. Soil moisture, and SOM, contents were estimated by loss on ignition (LOI), respectively at 105°C (values from 0.3 to 7.4 wt%), and 550°C (values from 2.1 to 21.0 wt%). SOC contents (values from 0.7 to 9.3 wt%) were determined through DIN19539 analysis performed with an Elementar soliTOC Cube. Using the ADAM platform, we associated a temporal series from 2016 to 2021 of the Sentinel 2 NDVI data product to each sampling location, using a cloud coverage mask to eliminate values taken on cloudy days. Localized phenological cycles for each year are recognizable in the remotely-sensed data. Hence, our database describes for each parcel, geochemical parameters and vegetative temporal series.In a separate study, we also attempted to train a neural network to predict geochemical properties from the soil spectrum measured by the hyperspectral satellite PRISMA. We used the geochemical properties of our 100 samples as training data, associated with the PRISMA spectra of the sampling locations measured on April 7 2020, when, according to our NDVI data, none was covered in vegetation.

In the upper mantle, volatiles control its composition, partial melting conditions, as well as the ascent rate of the formed melts. As consequence, volatile composition of the mantle is, in turn, recorded in the melts and, therefore, in the erupted basaltic rocks. Despite their importance, origin, budget, and fluxes of the volatiles in the upper mantle are poorly constrained. It is well known that the main input of mantle volatiles, such as carbon (C) and sulphur (S), represents components released from the subducting slab, e.g., oceanic rocks and sediments, whose have characteristic isotopic signatures. In this view, studies of isotopic ratios of volatiles of subduction-related magmatic rocks could be used to identify the chemical components released by the subducting slab metasomatizing the upper mantle. To confirm this hypothesis, we investigated the major and trace element composition, as well as the C and S elemental contents and isotopic ratios of subvolcanic and volcanic rocks of the Vardar ophiolites of North Macedonia, which represent remnants of the Mesozoic Tethyan oceanic lithosphere formed in supra-subduction zone tectonic settings.The ophiolites were sampled at Lipkovo and Demir Kapija localities, in the northern and southern part of North Macedonia, respectively. Based on whole-rock major and trace element composition, two main groups of rocks can be distinguished: i) Group 1 rocks, which are subalkaline basalts with backarc affinity and ii) Group 2 rocks, which are calc-alkaline basalts with arc affinity. The petrogenetic modelling based on trace and Rare Earth Elements, indicates that Group 1 mantle sources were affected by limited metasomatic processes by slab-released components, in particular aqueous fluids and sediment melts, whereas the Group 2 mantle sources were strongly metasomatized by sediment melts and adakitic melts. Accordingly, the Group 1 rocks exhibit C-enriched and S-depleted isotopic signature, indicating a minor involvement of melts from the subducting sediments. On the other hand, the C-depleted and S-enriched isotopic signatures of the Group 2 rocks suggest a major involvement of melts derived from the subducting sediments rich in organic matter and sulphate phases Therefore, both geochemical and isotopic data of the subvolcanic and volcanic samples of the North Macedonia ophiolites show that the sub-arc mantle sources are more affected by slab-released fluids than those of the backarc basin, which are more distal from the trench. Thus, combining the geochemical and isotopic data of subvolcanic and volcanic samples of complex geological framework can contribute to reconstruct the geodynamic scenarios, such as that of the Vardar ophiolites in the Dinaric-Hellenic belt. In addition, this approach may be useful to better understand the global geodynamic cycles of volatiles reconstructing their origin, budget, and isotopic composition, and understand the impacts on climate and environment from local to global scale.

Soil organic carbon (SOC) content is the major indicator used for soil quality evaluation because provides several ecosystem functions. However, SOC content does not allow to understand the soil potential to deliver the key ecosystem functions because most of soil processes are linked to soil biota. This research aimed to demonstrate the importance of soil indicators related to the SOC cycle rather than SOC content for soil quality evaluation. To reach this goal, three farms characterized by diverse soil types (Fluvisol and Cambisol) were selected in the Po plain of Emilia-Romagna Region, Italy. Moreover, different agricultural practices were performed: three-year-old pear trees using conventional management for Maccanti farm (MAC), 10-year pear orchard with integrated management for Zani (ZAN) and 10-year peach orchard with organic management for Biondi (BIO). MAC is located in ancient reclamation area, where Fluvisols are enriched of peat and organic matter. In each farm, soil samples from 0–15 (hereafter called topsoil) and 15–30 cm (hereafter called subsoil) depth were collected and analysed for the contents of SOC, labile organic carbon (Clab), fulvic acids, humic acids, humin and microbial biomass–C (Cmic), and for microbial respiration (Resp). In order to evaluate the soil processes related to C cycle, the humification rate (HR), metabolic quotient (qMET) and microbial quotient (qMIC) were calculated. MAC soil showed the highest SOC content without differences between topsoil and subsoil, due to ancient reclamation and agricultural management. BIO and ZAN showed similar SOC contents and it was higher in the topsoil than in subsoil due to grassy turf. Compared to BIO and ZAN, MAC soil showed a higher amount of Clab, and SOC was composed by a lower percentage of stable organic carbon (humin). Despite the higher Clab concentration, which is an easily available C source for microbes, no differences of Resp were observed among the sites, and MAC showed the lowest Cmic content. These data would indicate the presence in MAC of stress conditions which do not allow the growth of microbial biomass. The occurrence of stress conditions is clearly showed by the lowest qMET indicating how the conventional agricultural practices in peaty Fluvisol negatively affect the carbon use efficiency of microbial biomass. As a consequence, these stress conditions do not allow the C stabilization as suggested by the lowest qMIC. Further, the low C stabilization processes are highlighted by the highest HR. Conversely, despite the lowest content of Clab, BIO soil showed the lowest qMET and the highest qMIC suggesting how organic managements tend to improve the soil quality. Hence, the present study highlighted the importance of indicators linked to soil microbiome for soil quality evaluation in order to preserve its ecosystem functions. Indeed, organic carbon rich soils as those of MAC would indicate high quality soils but, because of the highly impacting practices, they showed stress conditions when the indicators linked to soil microbiome are taken in account. Therefore, if these indicators are not considered for soil quality evaluation, several fields used for agricultural purposes could become degraded.

The agricultural European Innovation Partnership (EIP-AGRI) Focus Group on Soil Organic Matter (SOM) content in Mediterranean regions highlighted the poor organic carbon (OC) content in the investigated soils, with some areas, especially in Southern Europe, showing low (≤2%) or even very low (≤1%) OC values. For this reason Emilia-Romagna Region (Northeastern Italy) invested heavily in the Rural Development Programme (RDP), which financed projects addressed to the needs of specific geographical areas. Among these, SaveSOC2 project (Save Soil Organic Carbon) aims to evaluate the quantity and quality of SOM in both conventional and organic farms from distinct pedo-climatic setting of Emilia-Romagna Region and with possible critical issues, in order to identify the best agricultural practices which could contribute to i) carbon conservation and sequestration in soil and ii) mitigation of SOM mineralization responsible for the greenhouses emissions. Here we report the data of the “Tassinari” organic farm located at Bondeno, near Ferrara city in Padania Plain, an area characterized by soil with very low amount of OC. In the selected organic farm, topsoil samples (0-15 cm and 15-30 cm depth) were collected from strawberry fields and orchards converted from conventional to organic production since 1992. The soils have loam and silt loam texture, they are subalkaline (pH: 7.9-8.7) and nonsaline (EC: 0.1-0.2 dS m-1). To characterize the soil inorganic (SIC) and organic (SOC) carbon, for each sample, elemental and isotopic analyses were performed using the Thermally Based Separation protocol tested by Natali et al. (2018) with an EA-IRMS. As expected, the vertical distribution of carbon along each site showed a negative correlation between SIC and SOC contents, as IC slightly increase over depth while OC show a clear decline. Moreover, irrespectively of the sampling depth, the OC values (0.90-1.14 wt.%) are always lower than those of IC (1.04-2.50 wt.%). The relatively low negative δ13C values of the total carbon (from -12.1‰ to -9.0‰) reflect the predominance of SIC in the investigated topsoils. The low storage of organic matter in this area is also confirmed by the OC stock value in the topsoils, which is on average 42.6 Mg/ha. A Soli TOC Cube® was also used to discriminate the labile organic carbon (TOC400) and the residual oxidizable carbon (ROC) fractions, which are oxidized at temperature below and above 400°C, respectively. In all the investigated topsoils, the TOC400 values (0.60-0.84 wt.%) are higher than those of ROC (0.21-0.28 wt.%), indicating large amount of “fresh” organic matter, and low amount of residual organic carbon. The high relative presence of labile OC pools, probably due to the soil fertilisation with easy available organic compounds, can be critical for SOM sequestration, preventing the accumulation of stabilised organic compounds. Natali C., Bianchini G., Vittori Antisari L. 2018. Thermal separation coupled with elemental and isotopic analysis: A method for soil carbon characterisation. Catena 164, 150-157.

In Lateglacial and Holocene stratigraphic sequences investigated in the eastern Po Plain (northern Italy), close to Bologna, black horizons are sometimes observed. Earlier paleo-environmental studies concerning this area have not interpreted origin and composition of these black buried horizons. In order to test this hypothesis, we are studying three stratigraphic sequences from Salara (SAL), San Mamolo (SMA) and Marzabotto (MRZ). To emphasize morphological characteristics (e.g., colour and thickness), a pedo-stratigraphic criterion was adopted for each layer observed in all the three stratigraphic sets. Totally, the horizons found are: 15 for SMA (two black), 14 for SAL (two black) and 6 for MRZ (one black); for each layer was sampled 1 kg of soil for the next investigations. Afterwards, the samples were treated in laboratory to carry out i) geochemical analyses of major, minor and trace elements, by XRF-WD Spectrometry, ii) carbon speciation in Organic (TOC) and Inorganic (TIC) fractions, by Soli TOC Cube (elemental analyser working in temperature ramp mode), iii) isotopic (δ13C) analysis, by EA-IRMS System. XRF analysis was necessary to understand how the black horizons are enriched or depleted in major, minor and trace elements compared to the other layers of the stratigraphic sections. Black horizons are enriched in Al2O3 (>14.95 wt%), Fe2O3 (>5.05 wt%), K2O (>2.27 wt%), TiO2 (>0.69 wt%), Ce (>45 mg kg-1), Cr (>148 mg kg-1), V (>91 mg kg-1), and depleted in CaO (13C has been measured for Total Carbon, TIC and TOC, and the values of black horizons are systematically more negative with respect to the other layers. The resulting values are a proxy of the type of vegetation coverage, reflecting the different proportions of C3 and C4 plants. The extremely negative values of black horizons suggest a prevalence of C3 plants during their formations, supporting the initial hypothesis of a connection with cold climatic periods. During these periods water was more acid thus explaining the paucity of carbonate. Pollen analysis is in progress to constrain this interpretation.

Construction and Demolition (C&D) waste is the solid debris resulting from construction and demolition activities. Recycling of this solid waste may result in substantial economic and environmental benefits. Unfortunately, is some Balkan countries such as Macedonia C&D recycling awareness is not developed yet. In this country, C&D are often dumped without control. According to the Macedonian landfill operator "Drisla" the estimated amounts of C&D waste generated per year in the Skopje surroundings approach 150.000 tons, but nothing is known on their composition. On this basis, a know-how exchange programme (KEP) called SAMCODE was financed by the Central European Initiative (CEI) and specifically dedicated to the characterization of C&D waste in Macedonia. GAYA operators sampled C&D landfills in the surroundings of Skopje, verified the absence of radioactivity, and then crushed the C&D down to the grain size of two millimetres. Crushed C&D chips were sent to the Department of Physics and Earth Sciences of the University of Ferrara, where the materials were powdered and analysed by X-ray fluorescence (XRF). Moreover, to characterize elemental mobility leaching tests on the C&D powders were carried out according to the following protocol: 1g of C&D powder has been soaked with 10 ml of deionized water, for 24 h. Subsequently the solutions have been centrifuged, filtered (at 45 mm) and analyzed by inductively coupled plasma mass spectrometry (ICP-MS). XRF analyses showed that – although variable - silica, calcium and aluminium are always the dominant components (SiO2 between 32 and 60 wt%, CaO between 7 and 30 wt%, Al2O3 between 7 and 16%) suggesting possible recycling in the ceramic/cement industrial processes. However, the real re-use of these materials in industrial processes is hampered by the lack of homogeneity, a feature required by the industries. The analysis of trace elements emphasized another critical aspect: Macedonian C&Ds often contain anomalously high concentrations of elements potentially hazardous, especially chromium (Cr), nickel (Ni), lead (Pb) and zinc (Zn). Note that the high concentrations of Cr, Ni, Zn and Pb do not necessarily recall the presence of contaminants, as these elements can be present in natural raw materials used in the country. Noteworthy, in Macedonia there are rocks included in the ophiolite sequences such as peridotites, serpentinites, pyroxenites and chromitites that can contain thousand(s) ppm of chromium and nickel, and also mining areas where there are sulphides of lead (galena) and zinc (sphalerite). If similar rocks are used as raw materials in the building activity, it is not strange to have C&D anomalously enriched in Cr, Ni, Pb, Zn. This hypothesis is confirmed by soil studies retrieved in the literature that highlighted that Macedonian soils can contain anomalous content of these elements. ICP-MS analyses of leachates show negligible concentrations of Ni, Pb and Zn, but significant concentrations of Cr. The results indicate that to foresee effective recycling Macedonian C&D have to be preliminarily screened to eliminate Cr-bearing components, crushed and sorted to obtain a better homogenization.

Glaciers are shrinking due to global warming, resulting in a diminishing contribution of ice- and snowmelt to headwaters with consequences on freshwater ecosystems. The stable isotopic compositions in natural waters (δ18O and δ2H) respond to environmental variation very sensitively and can indicate the change of geographic environment or mark the recharge of runoff (Boral 2019, Zuecco 2019). Thus, stable isotopes have been used as natural tracers to constrain the contributions of different water sources to streamflow, including snowmelt, icemelt and groundwater baseflow (Boral 2019). Within this context, we tested if water stable isotopes are spatio-temporal tracers of: i) water in periglacial habitats, being the isotopic signature of surface water inherited from the snow/icemelt, groundwater, and rainfall; ii) regional (year-specific) meteorological conditions, being the isotopic signature of precipitations affected by air temperature, humidity and aqueous vapour origin, ascribing stable isotopes in the list of the “essential climate variables″ (ECV). In this light, we investigated the ionic and isotopic composition (δ18O and δ2H) of six high altitude streams and one pond in the Italian Alps (Noce and Sarca basins) during the ablation season in 2018. Differences between habitat types (pond, kryal, rhithral, krenal) were detected. More negative values of δ18O and δ2H were recorded in the kryal and glacio-rhithral sites dominated by ice and snowmelt, in early summer. Less negative values were recorded in these sites in late summer and in krenal sites, dominated by groundwater and rainfall inputs. The isotopic results also showed that the complex alpine orography influences the air masses and moist, ultimately resulting in isotopic differences in precipitations of neighbouring, but distinct catchments (Sarca and Noce basins). As average, less negative values were recorded in the Sarca basin, characterized by a higher contribution of precipitation of Mediterranean origin. Finally, isotopic composition of the entire water population appeared to be strongly influenced by the regional climatic anomaly of the year 2018, which was anomalously warm in respect to the historical series 1961- 1990. This study will provide additional clues for the climate-change debate, proposing water isotopes as “essential climate variables″ indicators for assessing change in a warmer future. Keywords: stable isotopes, glaciers, essential climatic variables References: Boral S., J. Hydrol., https://doi.org/10.1016/j.jhydrol.2019.123983Zuecco G., Hydrol. Process, https://doi.org/10.1002/hyp.13366.

The exploitation of soils due to farming has produced a progressive loss of soil organic matter (SOM) over the years. At the same time, the degradation of SOM has led to a decline of several ecosystem services provided by soil, especially in mountain. Against this background, the partnership between Department of Physics and Earth Sciences of University of Ferrara and Department of Agricultural and Food Sciences of University of Bologna led to the creation of the SaveSOC2 project (Save Soil Organic Carbon), funded by Rural Development Programme of Emilia-Romagna Region. This project primarily seeks to investigate and promote carbon storage processes in agricultural soils of Emilia-Romagna Region (NE Italy). The present study outlines an overview about the SOM dynamics of “I Rodi” organic farm, located in the Modena Apennine. “I Rodi” produces and processes small organic fruits, especially raspberries. Three different sites (grassland -G, very low productive raspberries -LR, and good productive raspberries -GR) have been selected and the topsoils (0-15 cm and 15-30 cm) have been investigated. Elemental and isotopic analyses of soil C were performed using an EA-IRMS. In particular, the application of the Thermally Based Separation protocol [1] allowed the determination of both inorganic (IC) and organic (OC) carbon contents in each soil sample. OC accounted for 93.50% of the total carbon (1.72-4.84 wt.%). The negative δ13C values of the total carbon (from -27.8 to -19.7 ‰) confirmed the predominance of OC over IC in the investigated soils. The average values of OC isotopic C signature showed a decreasing trend among the three sites (-28.2, -27.2 and -25.8‰ for GR, G and LR, respectively), with the low productivity site having the highest δ13C value. The isotopic C signature of separated organic C fractions (0-15 cm topsoils) showed that humin (832-879 g/kg), which is the SOM fraction mostly interacting with the soil mineral phase and the largest pool, confirmed the observed trend (-27.5, -27.0, -26.4‰, GR, G and LR). The humic acids (6-17 g/kg) showed similar trend but lower δ13C values in all sites (-28.5, -28.0, -26.8 ‰, GR, G and LR). Finally, fulvic acids (5-10 g/kg) differed, having dissimilar trend and values of δ13C (-27.1, -26.8, -26.0 ‰ for G, GR and LR). Comparing to G, the GR data suggested that organic management i) did not decrease quantity and quality of organic matter, and ii) it was more efficient in OC stabilisation, increasing the amount of less transformed OC in both humin and humic acids (more negative δ13C values). In the LR site, instead, the observed trend can be due to low suitability of this soil to raspberries production, negatively affecting both crop yields and organic C dynamics. In our opinion, in order to combine agricultural productivity and its sustainability, more attention should be paid both to soil management and suitability in the area.[1] Natali C., Bianchini G., Vittori Antisari L. 2018. Thermal separation coupled with elemental and isotopic analysis: A method for soil carbon characterisation. Catena 164, 150-157.