Synergistic advantages of volcanic ash weathering in saline soils: CO2 sequestration and enhancement of plant growth

Carbon dioxide (CO2) is a primary greenhouse gas that has experienced a surge in atmospheric concentration due to human activities and lifestyles. It is imperative to curtail atmospheric CO2 levels promptly to alleviate the multifaceted impacts of climate warming. The soil serves as a natural reservoir for CO2 sequestration. The scientific premise of this study is that CO2 sequestration in agriculturally relevant, organically-deficient saline soil can be achieved by incorporating alkaline earth silicates. Volcanic ash (VA) was used as a soil amendment for CO2 removal from saline soil by leveraging enhanced silicate rock weathering (ERW). The study pursued two primary objectives: first, we aimed to evaluate the impact of various doses of VA, employed as an amendment for organically-deficient soil, on the growth performance of key cultivated crops (sorghum and mung bean) in inland saline-alkaline agricultural regions of northeastern China. Second, we aimed to assess alterations in the physical properties of the amended soil through mineralogical examinations, utilizing X-ray diffraction (XRD) and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS) analyses, quantifying the increase in inorganic carbon content within the soil. In the potting tests, mung bean plant height exhibited a noteworthy increase of approximately 41 % with the addition of 10 % VA. Sorghum plant height and aboveground and belowground biomass dry weights increased with VA application across all tested doses. At the optimal VA application rate (20 %), the sorghum achieved a CO2 sequestration rate of 0.14 kg CO2·m-2·month-1. XRD and SEM-EDS analyses confirmed that the augmented inorganic carbon in the VA-amended soils stemmed primarily from calcite accumulation. These findings contribute to elucidating the mechanism underlying VA as an amendment for organically-deficient soils and provide an effective approach for enhancing the carbon sink capacity of saline soils.

Variation of total alpha and beta activities and Rn-222 concentrations in the water supply system of an Italian volcanic region: How safe is tap water for human consumption?

Total alpha and beta activities and Rn-222 concentrations were determined in water from different sections of seven aqueducts belonging to the water supply system of Campania region (Italy), known worldwide for its volcanism. Statistical analysis was performed on data to account for their variability across the aqueduct sections, and results were discussed considering the geology of reservoirs, the potential mixing processes occurring along the pipe network, the building/constituting materials of the aqueduct sections, and the integrity of the infrastructure. Guidelines proposed by Italian and international regulation entities were considered to determine if total alpha and beta activities and Rn-222 concentrations found at the taps of the different aqueducts should be considered detrimental to public health. Based on a deterministic and a stochastic approach, a health risk assessment was also tested for Rn-222, assuming direct ingestion and showering as potential exposure pathways. Results showed that applying guidelines returned an absence of hazard, whereas risk assessment returned a high probability of exposure to unacceptable Rn-222 doses for some aqueducts. Beyond the usefulness of obtained results to plan actions to improve the safety of drinking water in Campania, our outcomes represent a warning for bodies dealing with public health at any level: the use of guidelines can bring an underestimation of the risks exerted by the exposure to Rn-222 on human health. Further, using a probabilistic approach in risk assessment accounting for uncertainty can favor risk forecasts based on more "realistic" scenarios.

Climate-forced Hg-remobilization associated with fern mutagenesis in the aftermath of the end-Triassic extinction

The long-term effects of the Central Atlantic Magmatic Province, a large igneous province connected to the end-Triassic mass-extinction (201.5 Ma), remain largely elusive. Here, we document the persistence of volcanic-induced mercury (Hg) pollution and its effects on the biosphere for ~1.3 million years after the extinction event. In sediments recovered in Germany (Schandelah-1 core), we record not only high abundances of malformed fern spores at the Triassic-Jurassic boundary, but also during the lower Jurassic Hettangian, indicating repeated vegetation disturbance and stress that was eccentricity-forced. Crucially, these abundances correspond to increases in sedimentary Hg-concentrations. Hg-isotope ratios (δ202Hg, Δ199Hg) suggest a volcanic source of Hg-enrichment at the Triassic-Jurassic boundary but a terrestrial source for the early Jurassic peaks. We conclude that volcanically injected Hg across the extinction was repeatedly remobilized from coastal wetlands and hinterland areas during eccentricity-forced phases of severe hydrological upheaval and erosion, focusing Hg-pollution in the Central European Basin.

Dhikr and Qur'an Recitation Therapy: An Idea to Recover the Mental Health of Families of the Death Victims of Mount Marapi Eruption in West Sumatra, Indonesia

BACKGROUND

Volcanic eruption is one of the most common disasters in Indonesia. One of the most fatal volcanic eruptions in Indonesia in 2023 was the eruption of Mount Marapi in West Sumatra. This caused a psychological impact on the survivors and families of the victims who died.

PROBLEM

Psychological interventions are usually only provided to survivors. It is very rare to find psychosocial assistance provided to the families of victims who died, even though they also experience acute and prolonged mental health disorders, such as trauma and even depression. So, we offer the idea of remembrance therapy and reading the Qur'an to restore the mental health of the families of the deceased victims.

CONCLUSION

Dhikr and Qur'an recitation therapy fosters sincerity, patience, and self-acceptance so as to restore mental health in the families of the victims of the Mount Marapi eruption. The therapy serves as a calming factor for the soul because it contains various wisdoms for the calamities experienced. The whole series of therapy is closed with prayer as a form of surrendering the soul to God.

Increased coral biomineralization due to enhanced symbiotic activity upon volcanic ash exposure

Coral reefs, which are among the most productive ecosystems on earth, are in global decline due to rapid climate change. Volcanic activity also results in extreme environmental changes at local to global scales, and may have significant impacts on coral reefs compared to other natural disturbances. During explosive eruptions, large amounts of volcanic ash are generated, significantly disrupting ecosystems close to a volcano, and depositing ash over distal areas (10s - 1000s of km depending on i.a. eruption size and wind direction). Once volcanic ash interacts with seawater, the dissolution of metals leads to a rapid change in the geochemical properties of the seawater column. Here, we report the first known effects of volcanic ash on the physiology and elemental cycling of a symbiotic scleractinian coral under laboratory conditions. Nubbins of the branching coral Stylophora pistillata were reared in aquaria under controlled conditions (insolation, temperature, and pH), while environmental parameters, effective quantum yield, and skeletal growth rate were monitored. Half the aquaria were exposed to volcanic ash every other day for 6 weeks (250 mg L-1 week-1), which induced significant changes in the fluorescence-derived photochemical parameters (ΦPSII, Fv/Fm, NPQ, rETR), directly enhanced the efficiency of symbiont photosynthesis (Pg, Pn), and lead to increased biomineralization rates. Enhancement of symbiont photosynthesis is induced by the supply of essential metals (Fe and Mn), derived from volcanic ash leaching in ambient seawater or within the organism following ingestion. The beneficial role of volcanic ash as an important micronutrient source is supported by the fact that neither photophysiological stress nor signs of lipid peroxidation were detected. Subaerial volcanism affects micronutrient cycling in the coral ecosystem, but the implication for coral ecophysiology on a reef scale remains to be tested. Nevertheless, exposure to volcanic ash can improve coral health and thus influence resilience to external stressors.

Synthesis of zeolites from volcanic ash (Tajogaite, Spain) for the remediation of waters contaminated by fluoride

In the eruptive event of Tajogaite (2021) in La Palma, Canary Islands, large quantities of volcanic ash were accumulated, affecting the local environment and urban areas. In this study, volcanic ash sampled from urban areas (catalogued as municipal waste (20 03 03) by the European Wastes Catalogue) were converted into zeolites by hydrothermal synthesis at 100 °C with previous alkaline fusion at 550 °C with distilled water. During this process, new phases of zeolite principally type X and sodalite have been identified by XRD at 2 h of incubation. These zeolites, with the course of incubation time, present competitive processes where the transformation into sodalite develops after 24 h as the predominant phase. The synthesized zeolitic material presents a high concentration as impurities in Fe2O3 (13.70 wt%), Na2O (12.70 wt%), CaO (11.65 wt%), and TiO2 (3.89 wt%) coming from the volcanic ash and NaOH introduced in the synthesis methodology. These impurities impart different physicochemical capabilities to the zeolitic material. The application of zeolites obtained in a preliminary fluoride adsorption experiment with volcanic leachate water rich in fluoride has been tested in a novel way. Removal efficiencies of 41.4% at acidic pH (5.77) have been obtained with 2 g L-1 adsorbent zeolitic material doses. A value-added material is obtained and applied in a preliminary way to solve a problem generated by the volcanic ash itself, allowing the End of Waste status and meeting different objectives of the sustainable development goals of the UN Agenda 2030.

Potentially harmful elements released by volcanic ash of the 2021 Tajogaite eruption (Cumbre Vieja, La Palma Island, Spain): Implications for human health

This study assesses the potential impacts on human health of volcanic ash emitted during the 2021 Tajogaite eruption (La Palma Island, Spain). Ash samples were physically and chemically characterized and leaching tests (with deionized water and acidic solution) were performed according to the IVHHN protocols to elucidate i) the leachable elements that may affect water quality and represent a potential threat for livestock and humans through drinking water supply; and ii) the bioaccessible fraction of toxicants able to be solubilized from ash surfaces if ashes are incidentally ingested by children. The most abundant readily water-soluble compounds were SO4, F, Cl, Na, Ca, Ba, Mg, and Zn. Fluoride and chloride (up to 1085 and 1347 mg/kg) showed higher values in distal ash samples than closer ones. The potential F availability assessed from water leachates may suggest important environmental and health implications. In addition, long-term health hazard due to a long-term weathering of tephra deposits should be possible as confirmed by the greater amount of F extracted by acidic solution. Concentration of other trace elements (e.g., As, V, Mn, Mo, Cr, Fe, Se, Ti, Pb) were low compared to global medians and within the range globally assessed. Indicative calculation of hazard for water supply showed that F concentration may exceed both the recommended value (1 mg/L) for irrigation purpose and the health-based drinking water limits of 1.5 mg/L (for humans) and 2 mg/L (for livestock). If the predicted concentrations in water were compared with the toxicologically dose, F showed a potential health-risk for children through drinking water. The indicative health-risk characterization via accidental ash ingestion showed that the direct exposure does not represent a primary source of F daily intake for children. This important outcome confirmed F as element with the greatest health threat during Tajogaite 2021 eruption.

Effect of particle size of nanoscale zero-valent copper on inorganic phosphorus adsorption-desorption in a volcanic ash soil

Zero-valent copper engineered nanoparticles (Cu-ENPs) released through unintentional or intentional actions into the agricultural soils can alter the availability of inorganic phosphorus (IP) to plants. In this study, we used adsorption-desorption experiments to evaluate the effect of particle size of 1% Cu-ENPs (25 nm and 40-60 nm) on IP availability in Santa Barbara (SB) volcanic ash soil. X-Ray Diffraction results showed that Cu-ENPs were formed by a mixture of Cu metallic and Cu oxides (Cu2O or/and CuO) species, while specific surface area values showed that Cu-ENPs/25 nm could form larger aggregate particles compared to Cu-ENPs/40-60 nm. The kinetic IP adsorption of SB soil without and with 1% Cu-ENPs (25 nm and 40-60 nm) followed the mechanism described by the pseudo-second-order (k2 = 0.45-1.13 x 10-3 kg mmol-1 min-1; r2 ≥ 0.999, and RSS ≤ 0.091) and Elovich (α = 14621.10-3136.20 mmol kg-1 min-1; r2 ≥ 0.984, and RSS ≤ 69) models. Thus, the rate-limiting step for IP adsorption in the studied systems was chemisorption on a heterogeneous surface. Adsorption equilibrium isotherms without Cu-ENPs were fitted well to the Freundlich model, while with 1% Cu-ENPs (25 nm and 40-60 nm), isotherms were described best by the Freundlich and/or Langmuir model. The IP relative adsorption capacity (KF) was higher with 1% Cu-ENPs/40-60 nm (KF = 110.41) than for 1% Cu-ENPs/25 nm (KF = 74.40) and for SB soil (KF = 48.17). This study showed that plausible IP retention mechanisms in the presence of 1% Cu-ENPs in SB soil were: i) ligand exchange, ii) electrostatic attraction, and iii) co-precipitate formation. The desorption study demonstrated that 1% Cu-ENPs/40-60 nm increased the affinity of IP in SB soil with a greater effect than 1% Cu-ENPs/25 nm. Thus, both the studied size ranges of Cu-ENPs could favor an accumulation of IP in volcanic ash soils.

Forced changes in the Pacific Walker circulation over the past millennium

The Pacific Walker circulation (PWC) has an outsized influence on weather and climate worldwide. Yet the PWC response to external forcings is unclear1,2, with empirical data and model simulations often disagreeing on the magnitude and sign of these responses3. Most climate models predict that the PWC will ultimately weaken in response to global warming4. However, the PWC strengthened from 1992 to 2011, suggesting a significant role for anthropogenic and/or volcanic aerosol forcing5, or internal variability. Here we use a new annually resolved, multi-method, palaeoproxy-derived PWC reconstruction ensemble (1200-2000) to show that the 1992-2011 PWC strengthening is anomalous but not unprecedented in the context of the past 800 years. The 1992-2011 PWC strengthening was unlikely to have been a consequence of volcanic forcing and may therefore have resulted from anthropogenic aerosol forcing or natural variability. We find no significant industrial-era (1850-2000) PWC trend, contrasting the PWC weakening simulated by most climate models3. However, an industrial-era shift to lower-frequency variability suggests a subtle anthropogenic influence. The reconstruction also suggests that volcanic eruptions trigger El Niño-like PWC weakening, similar to the response simulated by climate models.

Tropical Atlantic multidecadal variability is dominated by external forcing

The tropical Atlantic climate is characterized by prominent and correlated multidecadal variability in Atlantic sea surface temperatures (SSTs), Sahel rainfall and hurricane activity1-4. Owing to uncertainties in both the models and the observations, the origin of the physical relationships among these systems has remained controversial3-7. Here we show that the cross-equatorial gradient in tropical Atlantic SSTs-largely driven by radiative perturbations associated with anthropogenic emissions and volcanic aerosols since 19503,7-is a key determinant of Atlantic hurricane formation and Sahel rainfall. The relationship is obscured in a large ensemble of CMIP6 Earth system models, because the models overestimate long-term trends for warming in the Northern Hemisphere relative to the Southern Hemisphere from around 1950 as well as associated changes in atmospheric circulation and rainfall. When the overestimated trends are removed, correlations between SSTs and Atlantic hurricane formation and Sahel rainfall emerge as a response to radiative forcing, especially since 1950 when anthropogenic aerosol forcing has been high. Our findings establish that the tropical Atlantic SST gradient is a stronger determinant of tropical impacts than SSTs across the entire North Atlantic, because the gradient is more physically connected to tropical impacts via local atmospheric circulations8. Our findings highlight that Atlantic hurricane activity and Sahel rainfall variations can be predicted from radiative forcing driven by anthropogenic emissions and volcanism, but firmer predictions are limited by the signal-to-noise paradox9-11 and uncertainty in future climate forcings.

Organic walled microfossils in wet peperites from the early Cretaceous Paraná-Etendeka volcanism of Brazil

Large igneous provinces (LIPs) are major magmatic events that have a significant impact on the global environment and the biosphere, for example as triggers of mass extinctions. LIPs provide an excellent sedimentological and geochemical record of short but intense periods of geological activity in the past, but their contribution towards understanding ancient life is much more restricted due to the destructive nature of their igneous origin. Here, we provide the first paleontological evidence for organic walled microfossils extracted from wet peperites from the Early Cretaceous Paraná-Etendeka intertrappean deposits of the Paraná basin in Brazil. Wet peperites are a volcaniclastic rock formed by the interaction of lava and subaqueous sediments.The Paraná-Etendeka was formed during the Valanginian (ca. 132 Ma) as a continental flood basalt in present day South America and Namibia, and released enormous amounts of carbon dioxide, sulfur dioxide, methane and hydrogen fluoride into the atmosphere. The organic walled microfossils recovered from the Paraná-Etendeka peperites include pollen grains, spores, acritarchs, and other remains of unidentifiable organic matter. In addition to the peperites, organic walled microfossils were also found in heterolithic sandstones and interpillow sandstones. Our findings represent the first insight into the biodiversity of the Paraná Basin during the Early Cretaceous during a period of intense magmatism, and the microfossil assemblages corroborate a regional paleoclimatic transition from arid to more humid conditions that were likely induced by the volcanic activity. We corroborate the potential of wet peperite rocks as a valuable source of paleobiological data and emphasize the importance of sampling volcaniclastic units that have been traditionally considered with lower fossiliferous potential due to their igneous origin.

Rift-induced disruption of cratonic keels drives kimberlite volcanism

Kimberlites are volatile-rich, occasionally diamond-bearing magmas that have erupted explosively at Earth's surface in the geologic past1-3. These enigmatic magmas, originating from depths exceeding 150 km in Earth's mantle1, occur in stable cratons and in pulses broadly synchronous with supercontinent cyclicity4. Whether their mobilization is driven by mantle plumes5 or by mechanical weakening of cratonic lithosphere4,6 remains unclear. Here we show that most kimberlites spanning the past billion years erupted about 30 million years (Myr) after continental breakup, suggesting an association with rifting processes. Our dynamical and analytical models show that physically steep lithosphere-asthenosphere boundaries (LABs) formed during rifting generate convective instabilities in the asthenosphere that slowly migrate many hundreds to thousands of kilometres inboard of rift zones. These instabilities endure many tens of millions of years after continental breakup and destabilize the basal tens of kilometres of the cratonic lithosphere, or keel. Displaced keel is replaced by a hot, upwelling mixture of asthenosphere and recycled volatile-rich keel in the return flow, causing decompressional partial melting. Our calculations show that this process can generate small-volume, low-degree, volatile-rich melts, closely matching the characteristics expected of kimberlites1-3. Together, these results provide a quantitative and mechanistic link between kimberlite episodicity and supercontinent cycles through progressive disruption of cratonic keels.

Tonga national emergency medical team response to the 2022 Hunga Tonga-Hunga Ha'apai volcanic eruption and tsunami: the first deployment of the Tonga Emergency Medical Assistance Team (TEMAT)

Problem

The undersea Hunga Tonga-Hunga Ha'apai volcano erupted on 15 January 2022, causing a tsunami that affected Tonga as well as other countries around the Pacific rim. Tonga's international borders were closed at the time due to the coronavirus disease pandemic, but clinical surge support was needed to respond to this disaster.

Context

Tonga's Ministry of Health formed the Tonga Emergency Medical Assistance Team (TEMAT) in 2018 to provide clinical care and public health assistance during disasters, outbreaks and other health emergencies. TEMAT was activated for the first time in January 2022 to respond to medical and public health needs following the eruption and tsunami.

Action

On 16 January 2022, a five-person TEMAT advance team was deployed to conduct initial damage assessments and provide casualty care. Subsequently, TEMAT rotations were deployed to provide clinical care and public health support across the Ha'apai island group for over 2 months.

Outcome

TEMAT deployed to the islands most affected by the volcanic eruption and tsunami within 24 hours of the event, providing emergency clinical, psychosocial and public health services across four islands. TEMAT reported daily to the Ministry of Health and National Emergency Management Office, providing critical information for response decision-making. All TEMAT actions were documented, and an after-action review was conducted following the deployment.

Discussion

TEMAT's deployment in response to the 2022 volcanic eruption and tsunami highlighted the importance of national emergency medical teams that are prepared to respond to a range of emergency events.

Regional transportation and influence of atmospheric aerosols triggered by Tonga volcanic eruption

A cataclysmic submarine volcano at Hunga Tonga-HungaHa'apai (HTHH) near Tonga, erupted violently on 15 January 2022, which injected a plume of ash cloud soaring into the upper atmosphere. In this study, we examined the regional transportation and potential influence of atmospheric aerosols triggered by HTHH volcano, based on active and passive satellite products, ground-based observations, multi-source reanalysis datasets and atmospheric radiative transfer model. The results indicated that about 0.7 Tg (1 Tg = 10⁹ kg) sulfur dioxide (SO₂) gas were emitted into stratosphere from the HTHH volcano, and were lifted to an altitude of 30 km. The regional averaged SO₂ columnar content over the western Tonga increased by 10-36 Dobson Units (DU), and the mean aerosol optical thickness (AOT) retrieved from satellite products increased to 0.25-0.34. The stratospheric AOT values caused by HTHH emissions increased to 0.03, 0.20, and 0.23 on 16, 17, and 19 January, respectively, accounting for 1.5%, 21.9%, and 31.1% of total AOT. Ground-based observations also showed an AOT increase of 0.25-0.43, with the maximum daily average of 0.46-0.71 appeared on 17 January. The volcanic aerosols were remarkably dominated by fine-mode particles and posed strong light-scattering and hygroscopic abilities. Consequently, the mean downward surface net shortwave radiative flux was reduced by 2.45-11.9 Wm^-2 on different regional scales, and the surface temperature decreased by 0.16-0.42 K. The maximum aerosol extinction coefficient was 0.51 km^-1 appeared at 27 km, which resulted in an instantaneous shortwave heating rate of 1.80 Khour^-1. These volcanic materials stayed stable in the stratosphere and completed one circle around the earth within 15 days. This would exert a profound influence on the energy budget, water vapor and ozone exchange in the stratosphere, which deserves to be further studied.

Synergistic gel formation in geopolymers of superior mechanical strength synthesized with volcanic ash and slag

The present work studies gel evolution and microstructure of geopolymers synthesized with volcanic ash (VA) and blast furnace slag (BFS). The synthesis parameters such as BFS proportions on geopolymer formation were investigated. Gel evolution and microstructure of the geopolymers were studied by FTIR, X-ray diffraction (XRD), ²⁹Si NMR spectroscopy and scanning electron microscopy measurements. Silicate gels (N-S-H) were mainly formed in VA-based geopolymers of low compressive strength (14.07 MPa). While with VA and BFS each account for 50%, VA-BFS-based geopolymers possessed a compressive strength of 55.6 MPa, as well as the homogeneous C-(A)-S-H and N-A-S-H gels were formed. The C-(A)-S-H and N-A-S-H gels show synergistic effects on the mechanical property of the geopolymers. This work provides a clue for the synthesis of geopolymers with superior mechanical properties in areas of architecture. Detailed characterization gel evolution and microstructure of geopolymers synthesized with volcanic ash (VA) and blast furnace slag (BFS) were studied. Silicate gels (N-S-H) were mainly formed in VA-based geopolymers of low compressive strength (14.07 MPa). When VA and BFS each account for 50%, VA-BFS-based geopolymers possessed a compressive strength of 55.6 MPa, as well as the homogeneous C-(A)-S-H and N-A-S-H gels formed. Synthesis protocol for VA-BFS-based geopolymers.

Dispersion of arsenic species from highly explosive historical volcanic eruptions in Patagonia

Andean volcanic rocks typically have low to moderate arsenic (As) concentrations. However, elevated levels of As in groundwaters of southern South America have been reported as a consequence of weathering of volcanic glass. This study discusses the abundance, speciation and dispersion of As species in fresh volcanic ash from highly explosive (Volcanic Explosivity Index: 4-5) Patagonian eruptions, as well as the potential of As release to aqueous reservoirs. Synchrotron-based X-ray absorption and micro-focused X-ray photoelectron spectroscopies were used to evaluate As solid speciation. Batch experiments at different pH conditions were performed with the aim of understanding the controls on As release to aqueous reservoirs. Bulk chemical and mineralogical characterizations were performed by inductively coupled plasma optical emission spectroscopy, X-ray diffraction and scanning electron microscopy/energy dispersive spectroscopy. Finally, to understand how As-bearing phases are spatially distributed after eruptions, simulations of volcanic ash emission, transport and deposition were performed. Results indicate that the concentration, speciation, and mobility of As in fresh Patagonian volcanic ash depend on the silica content of source magmas. Although the main As host in volcanic ash is Al-silicate glass, this phase is stable at neutral pH characteristic of most aqueous reservoirs. Higher contributions of As to water are associated with the more mobile As species that concentrate onto the surface of Al-silicate glass. Atmospheric dispersion simulations revealed that primary fallout of As-bearing ash has affected large areas in Patagonia, but also reached the Chaco-Pampean plain, where the presence of As-rich groundwater has been widely documented.

Characterization of a Vision-Based Tool for the Investigation of Geometric Characteristics of Ground-Deposited Volcanic Ash

With the support of public authorities and research institutions, volcanic ash fallout and its impact on the safety of people, infrastructure and services are addressed with the aim of defining protocols and instruments for the reliable and effective handling of related emergencies. Most of the solutions proposed in the literature on ash fallout monitoring suffer from high cost and are demanding in terms of installation and maintenance. The approach suggested in this work is based on the use of a low-cost vision embedded system and a dedicated algorithm which automatically processes acquired frames of ground-deposited volcanic ash in order to estimate the main geometric properties of each particle identified in the work area. A complete characterization of the system is presented, along with a robustness analysis of particle shapes, their orientation and their position in the inspected frame. An accuracy of ±40.2 µm (with a 3σ limit) and a resolution of 32.9 µm (in the worst case), over a framed area of 130 mm by 100 mm, were estimated; these values would fulfill the objectives of the application.

Measuring air pollution from the 2021 Canary Islands volcanic eruption

The eruption of the Cumbre Vieja volcano on the island of La Palma (Canary Islands, Spain) began on September 19, 2021 and ended on December 13, 2021. It lasted continuously for 85 days with short periods of calm when lava did not exit the cone of the volcano. Vast amounts of volcanic material, including ash and gases, were emitted into the environment. This research focuses on these emissions. The main objective is to use available open-source data to examine the impact on regional and local air quality. Data from the following sources were used: 1) Copernicus Atmosphere Monitoring Service (CAMS) data was used to track the transfer of volcanic SO₂ in the troposphere in early October over long distances from the source of the eruption, including Western and Eastern Europe, across the Atlantic Ocean and the Caribbean; 2) Data from ground monitoring stations measured the concentrations of SO₂ and PM₁₀ near the source; 3) AErosol RObotic NETwork (AERONET) data from the La Palma station that showed high Aerosol Optical Depth (AOD) values (over 0.4) during the active phase of emissions on September 24 and 28, as well as on October 3; 4) Ångström Exponent (AE) values indicated the presence of particles of different sizes. On September 24, high AE values (>1.5), showed the presence of fine-mode fraction scattering aerosols such as sulfates; 5) Cloud Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) data additionally confirmed the presence of sulfate and dust aerosols in the atmosphere over the region. However, the influence of Saharan dust on the atmosphere of the entire region could not be excluded. This research helps forecast air pollution resulting from large-scale volcanic eruptions and associated health risks to humans.

Lava Mapping Using Sentinel-1 Data after the Occurrence of a Volcanic Eruption-The Case of Cumbre Vieja Eruption on La Palma, Canary Islands, Spain

Volcanic eruptions pose a great threat to humans. In this context, volcanic hazard and risk assessment constitute crucial issues with respect to mitigating the effects of volcanic activity and ensuring the health and safety of inhabitants. Lava flows directly affect communities living near active volcanoes. Nowadays, remote sensing advances make it possible to effectively monitor eruptive activity, providing immediate and accurate information concerning lava evolution. The current research focuses on the mapping of the surface deformation and the analysis of lava flow evolution occurred on the island of La Palma, during the recent (2021) eruptive phase of the volcano. Sentinel-1 data covering the island were collected throughout the entire eruptive period, i.e., September 2021 until January 2022. The processing was based on amplitude-based and phase-based detection methods, i.e., Synthetic Aperture Radar interferometry (InSAR) and offset tracking. In particular, ground deformation occurred on the island, while Line-Of-Sight (LOS) displacements were derived from Sentinel-1 interferograms. Moreover, the evolution of lava flow velocity was estimated using Sentinel-1 imagery along with offset tracking technique. The maximum lava flow velocity was calculated to be 2 m/day. It was proved that both approaches can provide rapid and useful information in emergencies, especially in inaccessible areas. Although offset tracking seems a quite promising technique for the mapping of lava flows, it still requires improvement.

The January 2022 eruption of Hunga Tonga-Hunga Ha'apai volcano reached the mesosphere

Explosive volcanic eruptions can loft ash, gases, and water into the stratosphere, which affects both human activities and the climate. Using geostationary satellite images of the 15 January 2022 eruption of the Hunga Tonga-Hunga Ha'apai volcano, we find that the volcanic plume produced by this volcano reached an altitude of 57 kilometers at its highest extent. This places the plume in the lower mesosphere and provides observational evidence of a volcanic eruption injecting material through the stratosphere and directly into the mesosphere. We then discuss potential implications of this injection and suggest that the altitude reached by plumes from previous eruptions, such as the eruption of Mount Pinatubo in 1991, may have been underestimated because of a lack of observational data.

Unmanned aerial vehicles (UAVs) as a tool for hazard assessment: The 2021 eruption of Cumbre Vieja volcano, La Palma Island (Spain)

Monitoring for assessment of natural disasters, such as volcanic eruptions, presents a methodological challenge for the scientific community. Here, we present Unmanned Aerial Vehicles (UAVs) as a feasible, precise, rapid and safe tool for real time monitoring of the impacts of a volcanic event during the Cumbre Vieja eruption on La Palma Island, Spain (2021). UAV surveys with optical RGB (Red-Green-Blue), thermal and multispectral sensors, and a water sampling device, were carried out in different areas affected by the lava flow, including the upper volcanic edifice and the lava delta formed on the coastal fringe of the island. Our results have provided useful information for the monitoring of the advance of the lava flow and its environmental consequences during the volcanic emergency. Our data shows how La Palma island's growth, with the formation of a new lava delta of 28 ha and a total volume of lava injected into the sea of 5,138,852 m³. Moreover, our Digital Elevation Model (DEM) simulated, with a 70 % accuracy, the probabilistic simulation of the possible path followed by the lava flow in the vicinity of the fissure from which the magma emanates. In addition, significant changes of seawater physical-chemical parameters were registered in coastal surface waters by the in situ seawater samples collected with the automatic water sampling device of our UAV. The first meters of the water column, due to the instant evaporation of the seawater in contact with the hot lava, produce an increase of temperature and salinity of up to 4-5 °C and up to 5 units, respectively.

Characterization of Volcanic Cloud Components Using Machine Learning Techniques and SEVIRI Infrared Images

Volcanic explosive eruptions inject several different types of particles and gasses into the atmosphere, giving rise to the formation and propagation of volcanic clouds. These can pose a serious threat to the health of people living near an active volcano and cause damage to air traffic. Many efforts have been devoted to monitor and characterize volcanic clouds. Satellite infrared (IR) sensors have been shown to be well suitable for volcanic cloud monitoring tasks. Here, a machine learning (ML) approach was developed in Google Earth Engine (GEE) to detect a volcanic cloud and to classify its main components using satellite infrared images. We implemented a supervised support vector machine (SVM) algorithm to segment a combination of thermal infrared (TIR) bands acquired by the geostationary MSG-SEVIRI (Meteosat Second Generation-Spinning Enhanced Visible and Infrared Imager). This ML algorithm was applied to some of the paroxysmal explosive events that occurred at Mt. Etna between 2020 and 2022. We found that the ML approach using a combination of TIR bands from the geostationary satellite is very efficient, achieving an accuracy of 0.86, being able to properly detect, track and map automatically volcanic ash clouds in near real-time.

The influence of the degassing phase of the Tagoro submarine volcano (Canary Islands) on the metal content of three species of cephalopods

Underwater volcanic eruptions are a type of natural contamination that affect all marine organisms at a local level. These eruptions usually begin and end a degassing stage of the volcano that, although they do not affect the magnitude of magma emanation, affect organisms to a lesser degree locally, such as cephalopods that due to their metabolism and trophic level, are good bioindicators of contamination. A total of 180 samples of three species of cephalopods were collected for the study: sixty Sepia officinalis, sixty Octopus vulgaris and sixty Loligo vulgaris in the area of the submarine volcano in El Hierro, Tenerife and Lanzarote in the Canary Islands (twenty samples per species in each location), and the metal concentrations (Al, Cd, Cr, Cu, Fe, Li, Ni, Pb and Zn) in each of the samples were analyzed. All species showed significant differences for all metals in El Hierro compared to Tenerife and Lanzarote. All the analyzed species from El Hierro had higher concentrations of the nine studied metals, this is due to the fact that they were caught near the Tagoro submarine volcano, which at the time was in a state of degassing and discharged many metal-rich compounds.

Biogeochemical Characteristics of Earth's Volcanic Permafrost: An Analog of Extraterrestrial Environments

This article describes a study of frozen volcanic deposits collected from volcanoes Tolbachik and Bezymianny on the Kamchatka Peninsula, Russia, and Deception Island volcano, Antarctica. In addition, we studied suprasnow ash layers deposited after the 2007 eruptions of volcanoes Shiveluch and Bezymianny on Kamchatka. The main objectives were to characterize the presence and survivability of thermophilic microorganisms in perennially frozen volcanic deposits. As opposed to permafrost from the polar regions, viable thermophiles were detected in volcanic permafrost by cultivation, microscopy, and sequencing. In the permafrost of Tolbachik volcano, we observed methane formation by both psychrophilic and thermophilic methanogenic archaea, while at 37°C, methane production was noticeably lower. Thermophilic bacteria isolated from volcanic permafrost from the Deception Island were 99.93% related to Geobacillus stearothermophilus. Our data showed biological sulfur reduction to sulfide at 85°C and even at 130°C, where hyperthermophilic archaea of the genus Thermoproteus were registered. Sequences of hyperthermophilic bacteria of the genus Caldicellulosiruptor were discovered in clone libraries from fresh volcanic ash deposited on snow. Microorganisms found in volcanic terrestrial permafrost may serve as a model for the alien inhabitants of Mars, a cryogenic planet with numerous volcanoes. Thermophiles and hyperthermophiles and their metabolic processes represent a guideline for the future exploration missions on Mars.

Disaster aid? Mapping historical responses to volcanic eruptions from 1800-2000 in the English-speaking Eastern Caribbean: their role in creating vulnerabilities

This paper uses volcanic eruptions on the Caribbean islands of Montserrat and Saint Vincent to explore the role that British colonial rule in the past and near past (1800-2000) has played in response to and recovery from hazardous events, and in turn, the influence that the nature of the hazards has on these responses. It shows that systemic vulnerabilities to natural hazards have been created by inadequate aid responses and longer-term chronic problems and demonstrates that hazard impacts are compounded by them. Vulnerabilities could be reduced by analysing integrated hazard impacts to generate mitigative measures across hazards and identify actions that more closely match timescales of political decision-making. Incorporating local knowledge and experience into risk analysis will enable the most effective use of aid resources, ahead of emergencies. Finally, coupling aid for long-term development with emergency response would improve outcomes and adaptation to longer-term vulnerabilities in immediate rebuilding and short-term recovery.

Did black volcanic rock help spark early life?

Quenched lava may have helped form long RNA strands vital to primordial organisms.

The relationship between volcanism and global climate changes in the Tropical Western Pacific over the mid-Pleistocene transition: Evidence from mercury concentration and isotopic composition

Volcanoes are a significant component of the Earth system, influencing the interaction between oceans and the atmosphere over large spatial and temporal scales. Being a volcanically dynamic region, the Tropical Western Pacific (TWP) can significantly impact variations in global climate. However, high-resolution continuous records of volcanic activity in this region are lacking, resulting in significant uncertainties regarding the coupling between the deep earth, climate changes, and atmospheric CO₂ in the TWP. To address this issue, mercury (Hg) levels, isotopic compositions, and Hg/total organic carbon (Hg/TOC) ratios were determined at site U1486 to track volcanic activity throughout the mid-Pleistocene transition (MPT) from 1.3 Myr to 0.6 Myr. Our results of anomalously high Hg concentrations and Hg/TOC ratios provide evidence of time-varying volcanism throughout the MPT. Mercury isotopes in the Hg-enriched sediments were characterized by near-zero Δ¹⁹⁹Hg values, which is consistent with volcanism acting as the primary source of Hg to the sediments. Spectral analysis of the Hg/TOC ratio showed significant periodicity at ~100 kyr and ~ 23 kyr as well as a weaker signal at ~41 kyr consistent with Milankovitch cycles. A cross spectral analysis of Hg/TOC and the LR04 δ¹⁸O stack record suggests that the peak in volcanism lags the temperature minimum by ~6 kyr, and occurs prior to the δ¹⁸O minimum known as the glacial termination by ~14 ± 2 kyr. The records of volcanic activity in this site are also consistent with a prominent rise in atmospheric CO₂ and negative excursion of benthic carbon isotopes throughout the MPT. This study provides direct sedimentary evidence in the TWP of the feedback between volcanic activity, climate change and atmospheric CO₂.

Occurrence of Volcanogenic Inorganic Mercury in Wild Mice Spinal Cord: Potential Health Implications

Mercury accumulation has been proposed as a toxic factor that causes neurodegenerative diseases. However, the hazardous health effects of gaseous elemental mercury exposure on the spinal cord in volcanic areas have not been reported previously in the literature. To evaluate the presence of volcanogenic inorganic mercury in the spinal cord, a study was carried out in São Miguel island (Azores, Portugal) by comparing the spinal cord of mice exposed chronically to an active volcanic environment (Furnas village) with individuals not exposed (Rabo de Peixe village), through the autometallographic silver enhancement histochemical method. Moreover, a morphometric and quantification analysis of the axons was carried out. Results exhibited mercury deposits at the lumbar level of the spinal cord in the specimens captured at the site with volcanic activity (Furnas village). A decrease in axon calibre and axonal atrophy was also observed in these specimens. Given that these are relevant hallmarks in the neurodegenerative pathologies, our results highlight the importance of the surveillance of the health of populations chronically exposed to active volcanic environments.

Water quality monitoring with Sentinel-2 and Landsat-8 satellites during the 2021 volcanic eruption in La Palma (Canary Islands)

In this study, seawater quality was monitored with high-resolution satellite imagery during the 2021 volcanic eruption (September-December) on La Palma Island (Spain), the longest recorded in the history of the island, and the most destructive in the last century in Europe. The Sentinel-2A/B twin satellites and Landsat-8 satellite were jointly used as an optical constellation, which allowed us to successfully characterize the short- and medium-term evolution of the new lava delta and subsequent impact on the seawater. Robust atmospheric and sunglint correction approaches were applied to thoroughly quantify the environmental changes caused on the adjacent coastal waters. The cloud and volcanic ash coverage remained very high over the coast during the event, so restricted information with 14 images (45% of the total scenes) was retrieved from the multi-sensor approach. Nevertheless, the availability of pre-, syn-, and post-eruption satellite products allowed us to map and detect the main water quality variations in the marine environment. On the one hand, during the eruption, a change in the properties of the water quality was observed, with a markedly increased turbidity on the western side of the island near the new lava delta due to the deposition of volcanic ash and material. On the other hand, chlorophyll-a concentration did not significantly increase, algal blooms were not observed, and oligotrophic conditions were not swiftly altered towards eutrophic conditions. This information offered an excellent opportunity to characterize the emplacement of the new lava delta and its impact on the marine environment in La Palma. The present multi-sensor strategy is an excellent opportunity to highlight the potential of remote sensing technology as a relevant and powerful tool for future hazard monitoring and assessment during catastrophes and for a better interpretation of their impact on the marine environment.

Element mobility related to rock weathering and soil formation at the westward side of the southernmost Patagonian Andes

Rock weathering and pedogenesis are fundamental processes for element mobility in terrestrial bio-geochemical cycles and for the regulation of primary productivity in adjacent coastal marine ecosystems. Here, soils developed from volcanic ash under extreme climate conditions could play a particular role. We therefore investigated rock weathering, soil formation and the associated mobilization of trace elements and micronutrients in a pristine South Patagonian ecosystem. Weathered and unweathered basement lithologies, tephra of the 4.216 kyrs BP Mt. Burney eruption and four soil profiles are considered. The approach combines mineralogical (XRD, SEM) and inorganic geochemical (XRF, ICP-OES/MS) with organic geochemical analyses (TOC, TN, δ¹³C, δ¹⁵N, DOC extracts) of representative samples. Chemical weathering is quantified by mass balance calculations and ¹⁴C age constraints allow a correlation of pedogenic processes with the paleoenvironmental history of the area. Our data document that pedogenesis with initial peat formation occurred since ~2.5 kyrs BP. In these acidic peaty Andosols, intensive alteration of volcanic glass mobilized large quantities of elements, considerably surpassing leachates provided by basement rock weathering. Clay production is limited in favor of the formation of amorphous Al- and crystalline Fe-(hydr)oxides. However, tephra alteration, soil organic matter turnover rates, enhanced dissolved organic carbon export, and Fe-/Al-(hydr)oxide precipitation are closely linked and ultimately controlled by rainfall-induced water-level fluctuations, highlighting the dominant influence of the southern westerly wind belt. The transport of mobilized trace elements and micronutrients adsorbed onto suspended colloids (dissolved organic carbon, Al-humus complexes and Fe-(hydr)oxides) is redox-pH-dependent, highly variable and ultimately regulated by westerly intensity. Broader implications of this work include a new perspective on the climate-controlled micronutrient delivery for primary productivity in South Patagonian fjords, which is strongly affected by Andosol formation. Furthermore, a careful evaluation of 'ordinary' geochemical proxies in regional paleoenvironmental archives is needed to account for these unique pedogenic processes.

Impact of chemical elements released by the volcanic eruption of La Palma (Canary Islands, Spain) on banana agriculture and European consumers

The recent volcanic eruption on the island of La Palma has aroused the concern of banana producers and consumers, given that in its area of influence there are thousands of hectares of banana plantations with an annual production of about 100 million kilos for export. Since volcanoes are one of the main natural sources of heavy metal contamination, we sampled bananas from the affected area and determined the concentrations of 50 elements (Ag, Al, As, Au, Ba, Be, Bi, Cd, Ce, Co, Cr, Cu, Cu, Dy, Er, Eu, Fe, Ga, Gd, Hg, Ho, In, La, Lu, Mn, Mo, Nb, Nd, Ni, Os, Pb, Pd, Pm, Pr, Pt, Sb, Sc, Se, Sm, Sn, Sr, Ta, Tb, Th, Ti, Tl, Tm, U, Y, Yb and Zn). The levels of 36 elements were elevated but the washing implemented after the eruption can remove a good part. After the washout, bananas have elevated levels of Fe, Al, Ti, V, Ba, Pb, most of the rare earth elements, Mo, and Co. In all cases, except Mo, the elevation is much higher in the peel than in the flesh. In the case of Mo, the elevation in banana flesh would translate into a higher nutritional intake of this trace element, which could represent up to 35% of the daily nutritional requirements. Exposure to toxic or potentially toxic elements, does not represent a health risk, since would not exceed 5% of the tolerable daily intake, even in the worst-case scenario.

Transient electromagnetic characteristics of coal seams intruded by magmatic rocks

The intrusion of magmatic rocks into coal seams affects the coal quality and leads to unforeseen hazards in safety of the coal mines’ production. This paper summarizes the mechanism of magmatic rocks intruding into coal seams, depicts the electromagnetic characteristics of the coal seams intruded by magmatic rocks, briefly describes the characteristics of transient electromagnetic method (TEM), and introduces the method of detection by TEM and the data processing steps. Then, the effectiveness of TEM in detecting the ranges of the coal seams intruded by magmatic rocks is theoretically analysed. It is observed that after the intrusion of magmatic rocks in the coal seams, the electromagnetic characteristics (secondary field potential and resistivity) will be dramatically affected, namely high secondary field potential and low resistivity. For experimental verification purposes, this study selects the test project of the Tongxin Minefield in the Datong Coalfield in Shanxi, China as an example, and the accuracy for the detection of the ranges of the coal seams intruded by magmatic rock using TEM is successfully verified.

Long-term responses of macroinvertebrate assemblages to the 2011 eruption of the Puyehue-Cordón Caulle volcanic complex, Chile

In June 2011 the Puyehue-Cordón Caulle volcanic complex (PCCVC) erupted, ejecting around 950 million metric tons of volcanic ash and pyroclastic rock, generating habitat destruction, environmental deterioration and devastation of ecological communities in rivers near the volcanic fissure. We evaluate the long-term effect of this eruptive event on the recovery of the diversity of aquatic macroinvertebrates, collecting biological and environmental information from 2011 to 2018 in visibly impacted Chilean rivers (Gol-Gol and Nilahue) and not visibly impacted rivers (Calcurrupe and Chanleufu). With the macroinvertebrate records we developed a recovery coefficient based on their diversity before and after the eruption. The results show that before the eruption (2009-2010), the accumulated family richness and mean diversity in the Gol-Gol River were higher than that observed post-eruption in rivers visibly impacted and not visibly impacted. Between 2013 and 2018, 17 families recolonized the Gol-Gol River, as well as 10 new families that were not recorded before the eruption. The richness of families post-eruption was negatively related to the increase in the concentration of total suspended solids, affecting the successional changes and recovery in the medium term. The recovery coefficient indicates that seven years after the eruption the diversity of macroinvertebrates still shows lower levels than those recorded before the eruptive event, with predominance of a slow recovery phase. Families of orders Ephemeroptera, Plecoptera and Trichoptera that were dominant before the eruption of the PCCVC began to recover the richness of taxa two years later, Plecoptera reaching 50% recolonization in 2018, Ephemeroptera 33.3% and Trichoptera 30%. In contrast, Diptera reached 100% recovery by 2018 and chironomids increased since 2015, becoming the dominant taxon during intermediate recovery in the Gol-Gol River. The recovery of macroinvertebrates in the Gol-Gol River is related to their modes of dispersal, feeding and the decrease in ash concentration.

Volcanic ash-driven worsening of mucosal inflammation in an experimental colitis model

Particulate matter exposure and related chemical changes in drinking water have been associated with health problems and inflammatory disorders. This study aimed to examine the effect of orally administered ash-water dilution on the gut of mice under normal and inflammatory conditions. Balb/c mice received ash-released soluble and dust-suspended components in the drinking water for 14 days. On day 7, animals were intrarectally instilled with TNBS in ethanol or flagellin from Salmonella typhimurium in PBS. At sacrifice, colon segments were collected and histologic damage, mRNA expression and cytokine levels in tissue were evaluated. In addition, these parameters were also evaluated in IL-10 null mice. We found that mice that received 5% w. fine-ash dilution in the drinking water worsened colitis signs. Weight loss, shortening of the colon, tissue edema with mucosa and submucosa cell infiltration and production of pro-inflammatory cytokines and chemokines were enhanced compared to control mice. A more pronounced inflammation was observed in IL-10 null mice. In addition, markers of NLRP3-dependent inflammasome activation were found in animals exposed to ash. In conclusion, ingestion of contaminated water with dust-suspended particulate matter enhanced the inflammatory response in the gut, probably due to alteration of the gut barrier and promoting an intense contact with the luminal content. This study critically appraises the response for fine particulate matter in uncommon illnesses reported for volcanic ash pollution. We suggest actions to enable better prediction and assessment the health impacts of volcanic eruptions.

Carbon reservoir perturbations induced by Deccan volcanism: Stable isotope and biomolecular perspectives from shallow marine environment in Eastern India

The Deccan Traps in Western India is hypothesized to have caused significant fluctuations in climatic condition and organic matter (OM) productivity across the Cretaceous-Paleogene Boundary (K/PgB). The periodic release of large amounts of volatiles into the atmosphere is thought to drive these changes. Yet, direct impact of volcanism on the carbon cycle and ecosystem remains relatively unconstrained. For the first time, we attempt to trace changes in both marine and terrestrial carbon reservoirs from pre- and intervolcanic sedimentary units (infra- and inter-trappeans respectively) from Rajahmundry, ~1500 km SE of main eruption sites in Western India. Molecular level characterization of OM and stable isotope composition of carbonates (δ¹³ C_carb ), bulk OM (δ¹³ C_org ), and n-alkane (δ¹³ C_alk and δD_alk ) have been analysed to provide a chemo-stratigraphic framework. In Rajahmundry, high CO₂ concentration estimated from infra-trappean carbonate nodule is synchronous with the onset of the Deccan Traps and the Late Maastrichtian warming episode. Impact of the warming event is reflected in Rajahmundry from a major shift in the terrestrial ecosystem. Marine OM production also seems to have been low throughout the infra-trappean. A steady decrease in δ¹³ C_carb values, increase in mortality rates and dwarfism in invertebrates immediately below the first volcanic units in Rajahmundry suggest stressed conditions from eruption in the western part of India ~40-60 kyrs prior to K/PgB. A significant increase in heterotrophic activity is observed after the volcanic deposits in Rajahmundry that seems to have controlled the marine carbon reservoir for a maximum of ~200 kyrs after the boundary. Advent of pteridophytes, increase in carbon content and positive shifts in δ¹³ C_carb and δ¹³ C_alk values in the upper inter-trappean units mark the onset of recovery in terrestrial and marine environments. Overall, our results suggest significant perturbations in the carbon reservoir as a consequence of the Deccan eruption.

When Red Turns Black: Influence of the 79 AD Volcanic Eruption and Burial Environment on the Blackening/Darkening of Pompeian Cinnabar

It is widely known that the vivid hue of red cinnabar can darken or turn black. Many authors have studied this transformation, but only a few in the context of the archeological site of Pompeii. In this work, the co-occurrence of different degradation patterns associated with Pompeian cinnabar-containing fresco paintings (alone or in combination with red/yellow ocher pigments) exposed to different types of environments (pre- and post-79 AD atmosphere) is reported. Results obtained from the in situ and laboratory multianalytical methodology revealed the existence of diverse transformation products in the Pompeian cinnabar, consistent with the impact of the environment. The effect of hydrogen sulfide and sulfur dioxide emitted during the 79 AD eruption on the cinnabar transformation was also evaluated by comparing the experimental evidence found on paintings exposed and not exposed to the post-79 AD atmosphere. Our results highlight that not all the darkened areas on the Pompeian cinnabar paintings are related to the transformation of the pigment itself, as clear evidence of darkening associated with the presence of manganese and iron oxide formation (rock varnish) on fragments buried before the 79 AD eruption has also been found.

Chronic exposure to volcanic gaseous elemental mercury: using wild Mus musculus to unveil its uptake and fate

Volcanoes are a natural source of gaseous elemental mercury (GEM) (Hg⁰). Monitoring GEM releases of volcanic origin has been widely studied; however, few studies have been performed about the biomonitoring of species exposed to GEM, rendering an unknown risk to the worldwide populations living in the vicinity of an active volcano. In this pilot study, we used Mus musculus as a bioindicator species to understand to what extent lungs are the main route of mercury uptake in populations chronically exposed to active volcanic environments. Autometallographic silver protocol was used to detect mercury deposits in the histological lung slides. Abundant mercury deposits were found in the lungs of specimens captured at the site with volcanic activity (Furnas Village, S. Miguel Island-Azores). The presence of mercury in the lungs could represent not only hazardous effects to the lung itself but also to other tissues and organs, such as brain and kidneys. This study confirms that the main uptake route for GEM is the lungs and that, even at very low concentrations in the environment, a chronic exposure to Hg⁰ results in its bioaccumulation in the lung tissue. These results reinforce that biomonitoring studies should be combined with monitoring classical approaches in order to better characterize the risks of exposure to Hg⁰ in volcanic environments.

Nanospeciation of metals and metalloids in volcanic ash using single particle inductively coupled plasma mass spectrometry

Volcanic activity is one of the main sources of natural nanoparticles. It has been found earlier that the concentration of toxic metals/metalloids in nanoparticles of volcanic ash may be one or two orders of magnitude higher than in bulk sample. However, fate and behavior of toxic metals/metalloids depend on the type of their binding to nanoparticles. Hence, element species adsorbed onto pyroclastic nanoparticles and individual nanophases of metal/metalloid oxides or salts should be distinguished. For the first time, the single particle inductively coupled plasma mass spectrometry has been applied to the nanospeciation of volcanic particles. Ashes of four volcanoes of Kamchatka (Russia) were under study. Nanoparticles were separated from bulk ash samples using coiled-tube field-flow fractionation. It has been shown that the nanospeciation of Ni, Zn, Ag, Cd, Tl, As, Pb, Bi, Te, and Hg is dependent on element and volcano. In most cases these elements can be found both as species absorbed onto pyroclastic nanoparticles and as individual nanophases. The ratios of individual nanophases and adsorbed species vary with the sample. In nanoparticles of Tolbachik volcano ash, Ni, Zn, Tl, and Hg are present only as individual nanophases, while Bi, As, Pb, Ag, Cd, and Te are found both as adsorbed species and individual nanophases. The results obtained open a new door into study on the chemical composition of volcanic ash nanoparticles and their fate in the environment.

Development of a simulated lung fluid leaching method to assess the release of potentially toxic elements from volcanic ash

Freshly erupted volcanic ash contains a range of soluble elements, some of which can generate harmful effects in living cells and are considered potentially toxic elements (PTEs). This work investigates the leaching dynamics of ash-associated PTEs in order to optimize a method for volcanic ash respiratory hazard assessment. Using three pristine (unaffected by precipitation) ash samples, we quantify the release of PTEs (Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V, Zn) and major cations typical of ash leachates (Mg, Na, Ca, K) in multiple simulated lung fluid (SLF) preparations and under varying experimental parameters (contact time and solid to liquid ratio). Data are compared to a standard water leach (WL) to ascertain whether the WL can be used as a simple proxy for SLF leaching. The main findings are: PTE concentrations reach steady-state dissolution by 24 h, and a relatively short contact time (10 min) approximates maximum dissolution; PTE dissolution is comparatively stable at low solid to liquid ratios (1:100 to 1:1000); inclusion of commonly used macromolecules has element-specific effects, and addition of a lung surfactant has little impact on extraction efficiency. These observations indicate that a WL can be used to approximate lung bioaccessible PTEs in an eruption response situation. This is a useful step towards standardizing in vitro methods to determine the soluble-element hazard from inhaled ash.

Pulmonary oxidative stress and apoptosis in mice chronically exposed to hydrothermal volcanic emissions

Recent studies have shown that exposure to hydrothermal emissions has a negative impact on the respiratory system. Still, volcanogenic air pollution studies are still outnumbered when compared to anthropogenic studies which can result in an unknown risk to the human populations living near volcanically active areas. This study was carried out in São Miguel Island, with noneruptive volcanically active environments, such as the Furnas volcano caldera. Its noneruptive volcanism presents itself as hydrothermal emissions, mainly by the release of nearly 1000 T d^-1 of CO₂ along with H₂S, and the radioactive gas radon; metals [e.g., mercury (Hg), cadmium (Cd), copper (Cu), and zinc (Zn)] and particulate matter are also released in a daily basis. We test the hypothesis whether chronic exposure to hydrothermal emissions causes pulmonary oxidative stress, using Mus musculus as a surrogate species. Mus musculus was live-captured in two villages with hydrothermal emissions and one village without any type of volcanic activity. The level of pulmonary oxidative stress was immunohistochemically assessed by using an OxyIHC^TM Oxidative stress detection kit, and the detection of terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end-labeling (TUNEL) was used to evaluate apoptosis in lung tissues. Mice chronically exposed to hydrothermal emissions presented increased levels of oxidative stress and amount of apoptotic cells. We demonstrate, for the first time, the high oxidative stress potential in the lungs of mice chronically exposed to hydrothermal emissions. This study highlights the usefulness of M. musculus as a bioindicator species and enforces the necessity of regularly biomonitor the inhabitants of hydrothermal areas to prevent respiratory pathologies.

Recovery of hydrothermal vent communities in response to an induced disturbance at the Lucky Strike vent field (Mid-Atlantic Ridge)

So far, the natural recovery of vent communities at large scales has only been evaluated at fast spreading centers, by monitoring faunal recolonisation after volcanic eruptions. However, at slow spreading ridges, opportunities to observe natural disturbances are rare, the overall hydrothermal system being more stable. In this study, we implemented a novel experimental approach by inducing a small-scale disturbance to assess the recovery potential of vent communities along the slow-spreading northern Mid-Atlantic Ridge (nMAR). We followed the recovery patterns of thirteen Bathymodiolus azoricus mussel assemblages colonising an active vent edifice at the Lucky Strike vent field, in relation to environmental conditions and assessed the role of biotic interactions in recolonisation dynamics. Within 2 years after the disturbance, almost all taxonomic richness had recovered, with the exception of a few low occurrence species. However, we observed only a partial recovery of faunal densities and a major change in faunal composition characterised by an increase in abundance of gastropod species, which are hypothesised to be the pioneer colonists of these habitats. Although not significant, our results suggest a potential role of mobile predators in early-colonisation stages. A model of post-disturbance succession for nMAR vent communities from habitat opening to climax assemblages is proposed, also highlighting numerous knowledge gaps. This type of experimental approach, combined with dispersal and connectivity analyses, will contribute to fully assess the resilience of active vent communities after a major disturbance, especially along slow spreading centers targeted for seafloor massive sulphide extraction.

Characterization of volcanic ash nanoparticles and study of their fate in aqueous medium by asymmetric flow field-flow fractionation-multi-detection

Dimensional and elemental characterization of environmental nanoparticles is a challenging task that requires the use of a set of complementary analytical methods. Asymmetric flow field-flow fractionation coupled with UV-Vis, multi-angle laser light scattering and ICP-MS detection was applied to study the nanoparticle fraction of a volcanic ash sample, in a Milli-Q water suspension at pH 6.8. It has been shown that the separated by sedimentation nanoparticle fraction of the Klyuchevskoy volcano ash suspension contains 3 polydisperse populations for which size ranges (expressed in gyration radius, rG), hydrodynamic behaviours (evaluated via shape index) and elemental compositions are different. These 3 populations did not dissolve over the 72-h study but aggregated and settled out differently. Thus, the population of particles with gyration radii <140 nm (P1), which contained 6% Al₂O₃ and represented approximately 20% by mass of the nanoparticle fraction, remained in suspension without observable aggregation. The populations P2 and P3, which represented 67% and 13% by mass in the initial suspension, covered the rG range 25-250 nm and contained 17% and 15% Al₂O₃, respectively. Over time, populations P2 and P3 aggregated and their concentration in suspension at 72 h decreased by approximately 40% compared with the initial suspension. The decrease of these nanoparticle populations occurred either from the beginning of the temporal monitoring (P2) or after 30 h (P3). Aggregation generated a new population (P4) in suspension with rG up to 300 nm and mostly consisting of P2. This population represented only up to 6 to 7% of the nanoparticle fraction and decreased beyond 50 h. As a result, the trace elements present in the nanoparticle fraction and monitored (Cu and La) were also no longer found in the suspension. The results obtained can offer additional insights into the fate of volcanic ash nanoparticles in the environment.

Reconciling early Deccan Traps CO2 outgassing and pre-KPB global climate

A 2 to 4 °C warming episode, known as the Latest Maastrichtian warming event (LMWE), preceded the Cretaceous-Paleogene boundary (KPB) mass extinction at 66.05 ± 0.08 Ma and has been linked with the onset of voluminous Deccan Traps volcanism. Here, we use direct measurements of melt-inclusion CO2 concentrations and trace-element proxies for CO2 to test the hypothesis that early Deccan magmatism triggered this warming interval. We report CO2 concentrations from NanoSIMS and Raman spectroscopic analyses of melt-inclusion glass and vapor bubbles hosted in magnesian olivines from pre-KPB Deccan primitive basalts. Reconstructed melt-inclusion CO2 concentrations range up to 0.23 to 1.2 wt% CO2 for lavas from the Saurashtra Peninsula and the Thakurvadi Formation in the Western Ghats region. Trace-element proxies for CO2 concentration (Ba and Nb) yield estimates of initial melt concentrations of 0.4 to 1.3 wt% CO2 prior to degassing. Our data imply carbon saturation and degassing of Deccan magmas initiated at high pressures near the Moho or in the lower crust. Furthermore, we find that the earliest Deccan magmas were more CO2 rich, which we hypothesize facilitated more efficient flushing and outgassing from intrusive magmas. Based on carbon cycle modeling and estimates of preserved lava volumes for pre-KPB lavas, we find that volcanic CO2 outgassing alone remains insufficient to account for the magnitude of the observed latest Maastrichtian warming. However, accounting for intrusive outgassing can reconcile early carbon-rich Deccan Traps outgassing with observed changes in climate and atmospheric pCO2.

Surface reactivity of Etna volcanic ash and evaluation of health risks

This work is a part of a research project conducted in order to characterize the volcanic ash from Mount Etna, focusing in particular on the surface reactivity of ashes and possible consequence for human health. In this framework, a sampling campaign began on 16 March 2013, taking advantage of the intense volcanic activity on Etna. The interaction between volcanic ash and human organism was simulated treating two classes of representative Etnean particles with ultrapure water (grainsize of 850 um) and Gamble's solution mimic lug fluids (grainsize <38 μm) with the aim to evaluate the risk due to gastric and respiratory exposure to volcanic particles. The leachates were analysed by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Ionic Chromatography (CI) in order to highlight possible dangerous elements released in water solutions according to USGS protocol. Analyses of Gamble's solution highlighted a release of elements smaller than in watery solutions and always below the thresholds established by the Italian law. On the contrary, analyses of watery solutions evidenced, for some elements (B, Cd, Ni and As), levels higher than permitted by Italian law. Considering the effects of these elements on human health, further investigations are necessary and currently carried out in order to better constrain the release process and the specific effects on human organism.