Luigi Dallai

Urban rivers represent a highly vulnerable environment due to the intense anthropogenic pressures and the restricted self‐depuration capacity. The current monitoring programs often lack to provide a full knowledge of all contaminant sources and processes governing their behaviour due to the complexity and variability of the conditions in urban water bodies and the increasing occurrence of new pollutants such as the Contaminants of Emerging concern (CECs). This called for an increasing regulatory attention and the need to carry out the revision of the Water Framework Directive (WFD), as it is currently ongoing. This study proposes an integrated new approach for urban water quality assessment, which combines traditional parameters, emerging contaminants, (i.e. CECs and Microplastics-MPs), isotopic tracing and modelling, with the aim of improving source discrimination and advancing the understanding of contaminant dynamics in heavily modified urban rivers. The new approach was tested on a selected stretch of the Tiber river, within the city of Rome. Data of pollutant concentrations, measured along the water body close by the point source releases, were combined with the hydraulic information through a mass‐balance approach with the aim to quantify contributions of different processes. The stable isotope ratios were evaluated as tracers for identifying contaminant origins and potential transformation processes, representing an innovative application in the context of urban river monitoring. Additionally, the Qual2K model was employed to simulate water‐quality dynamics under varying hydrological and meteorological conditions, focusing on the behaviour of CECs.

Commercial smooth-hound sharks of the genus Mustelus are commonly landed and consumed in Mediterranean fisheries, raising concerns about potential human exposure to persistent contaminants. This study investigated the occurrence of organochlorine compounds (OCs), including hexachlorobenzene (HCB), dichlorodiphenyltrichloroethane (DDT) and its metabolites, and polychlorinated biphenyls (PCBs), together with per- and polyfluoroalkyl substances (PFAS), in muscle and liver tissues of Mustelus mustelus and Mustelus punctulatus collected in the waters of the Egadi Archipelago (central Mediterranean Sea). OCs were detected in all analyzed samples, with total PCB concentrations reaching higher values in liver compared to muscle tissues, reflecting tissue-specific accumulation and detoxification processes. PFAS were detected in all analyzed muscle samples (1.10–58.5 ng/g w.w.), with PFOS, PFOA and PFNA generally below current European regulatory thresholds, although isolated exceedances were observed. Stable isotope analysis (δ¹³C and δ¹⁵N) highlighted differences in trophic ecology between the two species and suggested that feeding habitat and trophic position may influence contaminant exposure patterns, particularly in M. punctulatus. The human health risk assessment, conducted as a screening-level evaluation, indicated potential concern associated with PCB concentrations in liver tissue, while risks associated with muscle consumption were generally lower. Overall, the integration of contaminant analysis and stable isotopes provides insights into organismal exposure pathways and supports the use of smooth-hound sharks as sentinels of contaminant presence in Mediterranean coastal ecosystems.

The great white shark (Carcharodon carcharias), a keystone predator vital to marine ecosystem stability, is increasingly exposed to anthropogenic threats, including endocrine-disrupting chemicals (EDCs). This study highlights the use of non-invasive epidermal biopsies to assess physiological and ecological parameters in 28 live specimens sampled from the Dyer Island Nature Reserve, South Africa. Epidermal tissue was analyzed for vitellogenin (Vtg), a biomarker of estrogenic exposure, while dermal tissue was used for stable isotope analyses of carbon and nitrogen, essential for understanding the feeding habitat of white sharks. Vitellogenin, typically restricted to sexually mature females, was unexpectedly detected in males and immature females, indicating significant exposure to estrogenic pollutants. This finding raises concerns about the potential reproductive and population-level impacts on this vulnerable species. Stable isotope analyses confirmed that dermal tissue alone is sufficient for trophic studies, eliminating the need for deeper muscle sampling. By demonstrating that epidermal and dermal tissues provide critical data for both biomarkers and isotopic studies, this research supports the adoption of minimally invasive techniques. Shallower biopsies reduce stress on the animals, making this method a valuable tool for conservation research and management of C. carcharias.

Triple oxygen isotopes of Cenozoic intrusive rocks emplaced along the Ross Sea coastline in Antarctica, reveal that meteoric-hydrothermal waters imprinted their stable isotope composition on mineral phases, leaving a clear record of oxygen and hydrogen isotope variations during the establishment of the polar cap. Calculated O- and H-isotope compositions of meteoric waters vary from −9 ± 2‰ and −92 ± 5‰ at 40 ± 0.6 Ma, to −30 and −234 ± 5‰ at 34 ± 1.9 Ma, and intersect the modern Global Meteoric Water Line. These isotopic variations likely depict the combined variations in temperature, humidity, and moisture source regions, resulting from rearrangement of oceanic currents and atmospheric cooling during the onset of continental ice cap. Here, we report a paleo-climatic proxy based on triple oxygen geochemistry of crystalline rocks that reveals changes in the hydrological cycle. We discuss the magnitude of temperature changes at high latitudes during the Eocene-Oligocene climatic transition.

The occurrence of rhyolite melts in the mantle has been predicted by high pressure-high temperature experiments but never observed in nature. Here we report natural quartz-bearing rhyolitic melt inclusions and interstitial glass within peridotite xenoliths. The oxygen isotope composition of quartz crystals shows the unequivocal continental crustal derivation of these melts, which approximate the minimum composition in the quartz-albite-orthoclase system. Thermodynamic modelling suggests rhyolite was originated from partial melting of near-anhydrous garnet-bearing metapelites at temperatures ~1000 °C and interacted with peridotite at pressure ~1 GPa. Reaction of rhyolite with olivine converted lherzolite rocks into orthopyroxene-domains and orthopyroxene + plagioclase veins. The recognition of rhyolitic melts in the mantle provides direct evidence for element cycling through earth’s reservoirs, accommodated by dehydration and melting of crustal material, brought into the mantle by subduction, chemically modifying the mantle source, and ultimately returning to surface by arc magmatism.

Disentangling the effects of climate and human impact on the long-term evolution of the Earth Critical Zone is crucial to understand the array of its potential responses to the ongoing Global Change. This task requires natural archives from which local information about soil and vegetation can be linked directly to climate parameters. Here we present a high-resolution, well-dated, speleothem multiproxy record from the SW Italian Alps, spanning the last ~10,000 years of the present interglacial (Holocene). We correlate magnetic properties and the carbon stable isotope ratio to soil stability and pedogenesis, whereas the oxygen isotope composition is interpreted as primarily related to precipitation amount, modulated at different timescales by changes in precipitation source and seasonality. During the 9.7-2.8 ka period, when anthropic pressure over the catchment was scarce, intervals of enhanced soil erosion are related to climate-driven vegetation contractions and occurred during drier periods. Immediately following the onset of the Iron Age (ca. 2.8 ka), by contrast, periods of enhanced soil erosion coincided with a wetter climate. We propose that the observed changes in the soil response to climate forcing were related to early anthropogenic manipulations of Earth’s surface, which made the ECZ more sensitive to climate oscillations.

Magmas in volcanic arcs have geochemical and isotopic signatures that can be related to mantle metasomatism due to fluids and melts released by the down-going oceanic crust and overlying sediments, which modify the chemistry and mineralogy of the mantle wedge. However, the effectiveness of subduction-related metasomatic processes is difficult to evaluate because the composition of arc magmas is often overprinted by interactions with crustal lithologies occurring during magma ascent and emplacement. Here, we show unequivocal evidence for recycling of continental crust components into the mantle. Veined peridotite xenoliths sampled from Tallante monogenetic volcanoes in the Betic Cordillera (southern Spain) provide insights for mantle domains that reacted with Si-rich melts derived by partial melting of subducted crustal material. Felsic veins crosscutting peridotite and the surrounding orthopyroxene-rich metasomatic aureoles show the highest ¹⁸O/¹⁶O ratios measured to date in upper mantle assemblages worldwide. The anomalously high oxygen isotope compositions, coupled with very high ⁸⁷Sr/⁸⁶Sr values, imply the continental crust origin of the injected melts. Isotopic anomalies are progressively attenuated in peridotite away from the veins, showing ¹⁸O isotope variations well correlated with the amount of newly formed orthopyroxene. Diffusion may also affect the isotope ratios of mantle rocks undergoing crustal metasomatism due to the relaxation of ¹⁸O isotope anomalies to normal mantle values through time. Overall, the data define an O isotope “benchmark” allowing discrimination between mantle sources that attained re-equilibration after metasomatism (>5 Myr) and those affected by more recent subduction-derived enrichment processes.