Metallothionein expression in the central nervous system in response to chronic heavy metal exposure: possible neuroprotective mechanism

It has been reported that volcanoes release several tonnes of mercury per year among other heavy metals through eruptions, fumaroles, or diffuse soil degassing. Since a high percentage of the world's population lives in the vicinity of an active volcano, the aim of this study is to evaluate the accumulation of these metals in the central nervous system and the presence of cellular mechanisms of heavy metal detoxification such as metallothioneins. To carry out this study, wild mice (Mus musculus) chronically exposed to an active volcanic environment were captured in Furnas village (Azores, Portugal) and compared with those trapped in a reference area (Rabo de Peixe, Azores, Portugal). On the one hand, the heavy metal load has been evaluated by analyzing brain and cerebellum using ICP-MS and a mercury analyzer and on the other hand, the presence of metallothionein 2A has been studied by immunofluorescence assays. Our results show a higher load of metals such as mercury, cadmium and lead in the central nervous system of exposed mice compared to non-exposed individuals and, in addition, a higher immunoreactivity for metallothionein 2A in different areas of the cerebrum and cerebellum indicating a possible neuroprotection process.

Radon signature of CO2 flux constrains the depth of degassing: Furnas volcano (Azores, Portugal) versus Syabru-Bensi (Nepal Himalayas)

Substantial terrestrial gas emissions, such as carbon dioxide (CO₂), are associated with active volcanoes and hydrothermal systems. However, while fundamental for the prediction of future activity, it remains difficult so far to determine the depth of the gas sources. Here we show how the combined measurement of CO₂ and radon-222 fluxes at the surface constrains the depth of degassing at two hydrothermal systems in geodynamically active contexts: Furnas Lake Fumarolic Field (FLFF, Azores, Portugal) with mantellic and volcano-magmatic CO₂, and Syabru-Bensi Hydrothermal System (SBHS, Central Nepal) with metamorphic CO₂. At both sites, radon fluxes reach exceptionally high values (> 10 Bq m⁻² s⁻¹) systematically associated with large CO₂ fluxes (> 10 kg m⁻² day⁻¹). The significant radon‒CO₂ fluxes correlation is well reproduced by an advective–diffusive model of radon transport, constrained by a thorough characterisation of radon sources. Estimates of degassing depth, 2580 ± 180 m at FLFF and 380 ± 20 m at SBHS, are compatible with known structures of both systems. Our approach demonstrates that radon‒CO₂ coupling is a powerful tool to ascertain gas sources and monitor active sites. The exceptionally high radon discharge from FLFF during quiescence (≈ 9 GBq day⁻¹) suggests significant radon output from volcanoes worldwide, potentially affecting atmosphere ionisation and climate.

Impact on air quality of carbon and sulfur volatile compounds emitted from hydrothermal discharges: The case study of Pisciarelli (Campi Flegrei, South Italy)

Volcanoes are currently to be regarded as natural sources of air pollutants. Climatic and environmental forcing of large volcanic eruptions are well known, although gases emitted through passive degassing during periods of quiescence or hydrothermal activity can also be highly dangerous for the environment and public health. Based on compositional and isotopic data, a survey on the spatial distribution in air of the main volatile compounds of carbon (CO₂ and CH₄) and sulfur (H₂S and SO₂) emitted from the fumarolic field of Pisciarelli (Campi Flegrei, Pozzuoli, Naples), a hydrothermal area where degassing activity has visibly increased since 2009, was carried out. The main goals of this study were (i) to evaluate the impact on air quality of these natural manifestations and (ii) inquire into the behavior of the selected chemical species once released in air, and their possible use as tracers to distinguish natural and anthropogenic sources. Keeling plot analysis of CO₂ and CH₄ isotopes revealed that the hydrothermal area acts as a net source of CO₂ in air, whilst CH₄ originated mainly from anthropogenic sources. Approaching the urban area, anthropogenic sources of CO₂ increased and, at distances greater than 800 m from the Pisciarelli field, they prevailed over the hydrothermal signal. While hydrothermal CO₂ simply mixed with that in the atmospheric background, H₂S was possibly affected by oxidation processes. Therefore, SO₂ measured in the air near the hydrothermal emissions had a secondary origin, i.e. generated by oxidation of hydrothermal H₂S. Anthropogenic SO₂ was recognized only in the furthest measurement site from Pisciarelli. Finally, in the proximity of a geothermal well, whose drilling was in progress during our field campaign, the H₂S concentrations have reached values up to 3 orders of magnitude higher than the urban background, claiming the attention of the local authorities.

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.

Scientific response to the 2021 eruption of Nyiragongo based on the implementation of a participatory monitoring system

The development of a resilient society is a major challenge for growing human population faced with abundant natural hazards. During and after the May 22, 2021 eruption of Nyiragongo, the local population was surprised and scared by the subsequent seismicity and associated surface fracturing, coupled with the alert of a possible new eruptive vent opening in Goma (Democratic Republic of Congo) and/or Gisenyi (Rwanda). The creation of a toll-free phone number enabled the population to record fractures and gas/thermal anomalies affecting the area. Such work was fundamental in enabling scientists and authorities to assess the associated risks. Crucially, gas data showed that the degassing through fractures did not represent direct transfer of magmatic volatiles but was more likely of superficial origin. Surprisingly, this participatory work revealed that the first fractures appeared several weeks before the eruption and their opening was not detected by the monitoring system. This firmly underlines the need for scientists to anchor citizen science in monitoring strategies.

Evaluating the Impact of Explosive Volcanic Eruptions on a Groundwater-Fed Water Supply System: An Exploratory Study in Ponta Delgada, São Miguel (Azores, Portugal)

Tephra fall is among the set of hazardous phenomena associated with volcanic activity that can impact water resources and services. The aim of this paper is to characterize the potential impacts of tephra fall on the groundwater-fed water supply system of Ponta Delgada (São Miguel, Azores) by comparing two scenarios of explosive eruptions. Vulnerability matrices were used to compute indexes, by multiplying the thickness of tephra fall deposits, corresponding to increasing hazard levels, by descriptors of the water supply system, representing the elements at risk. In a worst-case scenario, tephra covers a large area inland, severely constraining the abstraction of water to public supply, as 84.8% of the springs are affected. In 12 springs the expected hazard level is of perturbation (5157 m3/day; 12.1% of the daily abstraction) or damage (16,094 m3/day; 37.8%). The same trend is observed considering the storage capacity, as 75.4% of the reservoirs may be somehow affected. Moreover, 72.4% of the 68,392 inhabitants served by the water supply system will be in a zone where the damage level will be achieved. Results point out to the need of preparedness measures to mitigate consequences of a volcanic crisis over the water supply.

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.

The Health Hazards of Volcanoes: First Evidence of Neuroinflammation in the Hippocampus of Mice Exposed to Active Volcanic Surroundings

Neuroinflammation is a process related to the onset of neurodegenerative diseases; one of the hallmarks of this process is microglial reactivation and the secretion by these cells of proinflammatory cytokines such as TNFα. Numerous studies report the relationship between neuroinflammatory processes and exposure to anthropogenic air pollutants, but few refer to natural pollutants. Volcanoes are highly inhabited natural sources of environmental pollution that induce changes in the nervous system, such as reactive astrogliosis or the blood-brain barrier breakdown in exposed individuals; however, no neuroinflammatory event has been yet defined. To this purpose, we studied resting microglia, reactive microglia, and TNFα production in the brains of mice chronically exposed to an active volcanic environment on the island of São Miguel (Azores, Portugal). For the first time, we demonstrate a proliferation of microglial cells and an increase in reactive microglia, as well an increase in TNFα secretion, in the central nervous system of individuals exposed to volcanogenic pollutants.

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.

Reactive astrogliosis in the dentate gyrus of mice exposed to active volcanic environments

Air pollution has been associated with neuroinflammatory processes and is considered a risk factor for the development of neurodegenerative diseases. Volcanic environments are considered a natural source of air pollution. However, the effects of natural source air pollution on the central nervous system (CNS) have not been reported, despite the fact that up to 10% of the world's population lives near a historically active volcano. In order to assess the response of the CNS to such exposure, our study was conducted in the island of Sao Miguel (Azores, Portugal) in two different areas: Furnas, which is volcanically active one, and compared to Rabo de Peixe, a reference site without manifestations of active volcanism using Mus musculus as a bioindicator species. To evaluate the state of the astroglial population in the dentate gyrus in both samples, the number of astrocytes was determined using immunofluorescence methods (anti-GFAP and anti-GS). In addition, the astrocytic branches in that hippocampal area were examined. Our results showed an increase in GFAP+ astrocytes and a reduction in GS+ astrocytes in Furnas-exposed mice compared to animals from Rabo de Peixe. In addition, astrocytes in the dentate gyrus of chronically exposed animals exhibited longer branches compared to those residing at the reference site. Thus, reactive astrogliosis and astrocyte dysfunction are found in mice living in an active volcanic environment.

First record on mercury accumulation in mice brain living in active volcanic environments: a cytochemical approach

The health effects of mercury vapor exposure on the brain in volcanic areas have not been previously addressed in the literature. However, 10% of the worldwide population inhabits in the vicinity of an active volcano, which are natural sources of elemental mercury emission. To evaluate the presence of mercury compounds in the brain after chronic exposure to volcanogenic mercury vapor, a histochemical study, using autometallographic silver, was carried out to compare the brain of mice chronically exposed to an active volcanic environment (Furnas village, Azores, Portugal) with those not exposed (Rabo de Peixe village, Azores, Portugal). Results demonstrated several mercury deposits in blood vessels, white matter and some cells of the hippocampus in the brain of chronically exposed mice. Our results highlight that chronic exposure to an active volcanic environment results in brain mercury accumulation, raising an alert regarding potential human health risks. These findings support the hypothesis that mercury exposure can be a risk factor in causing neurodegenerative diseases in the inhabitants of volcanically active areas.

Deep versus shallow sources of CO2 and Rn from a multi-parametric approach: the case of the Nisyros caldera (Aegean Arc, Greece)

Estimating the quantity of CO₂ diffusively emitted from the Earth’s surface has important implications for volcanic surveillance and global atmospheric CO₂ budgets. However, the identification and quantification of non-hydrothermal contributions to CO₂ release can be ambiguous. Here, we describe a multi-parametric approach employed at the Nisyros caldera, Aegean Arc, Greece, to assess the relative influence of deep and shallow gases released from the soil. In April 2019, we measured diffuse soil surface CO₂ fluxes, together with their carbon isotope compositions, and at a depth of 80 cm, the CO₂ concentration, soil temperature, and the activities of radon and thoron. The contributions of deep CO₂ and biogenic CO₂ fluxes were distinguished on the basis of their carbon isotope compositions. A Principal Component Analysis (PCA), performed on the measured parameters, effectively discriminates between a deep- and a shallow degassing component. The total CO₂ output estimated from a relatively small testing area was two times higher with respect to that observed in a previous survey (October 2018). The difference is ascribed to variation in the soil biogenic CO₂ production, that was high in April 2019 (a wet period) and low or absent in October 2018 (a dry period). Accounting for seasonal biogenic activity is therefore critical in monitoring and quantifying CO₂ emissions in volcanic areas, because they can partially- or completely overwhelm the volcanic-hydrothermal signal.

Chronic exposure to non-eruptive volcanic activity as cause of bronchiolar histomorphological alteration and inflammation in mice

It is estimated that 10% of the worldwide population lives in the vicinity of an active volcano. However, volcanogenic air pollution studies are still outnumbered when compared with anthropogenic air pollution studies, representing an unknown risk to human populations inhabiting volcanic areas worldwide. This study was carried out in the Azorean archipelago of Portugal, in areas with active non-eruptive volcanism. The hydrothermal emissions within the volcanic complex of Furnas (São Miguel Island) are responsible for the emission of nearly 1000 tons of CO₂ per day, along with H₂S, the radioactive gas - radon, among others. Besides the gaseous emissions, metals (e.g., Hg, Cd, Al, Ni) and particulate matter are also released into the environment. We test the hypothesis that chronic exposure to volcanogenic air pollution alters the histomorphology of the bronchioles and terminal bronchioles, using the house mouse, Mus musculus, as bioindicator species. Mus musculus were live-captured at three different locations: two villages with active volcanism and a village without any type of volcanic activity (reference site). The histomorphology of the bronchioles (diameter, epithelium thickness, smooth muscle layer thickness, submucosa thickness and the histological evaluation of the peribronchiolar inflammation) and of the terminal bronchioles (epithelium thickness and classification) were evaluated. Mice chronically exposed to volcanogenic air pollution presented bronchioles with increased epithelial thickness, increased smooth muscle layer, increased submucosa thickness and increased peribronchiolar inflammation. Similarly, terminal bronchioles presented structural alterations consistent with bronchodysplasia. For the first time we demonstrate that chronic exposure to non-eruptive volcanically active environments causes inflammation and histomorphological alterations in mice lower airways consistent with asthma and chronic bronchitis. These results reveal that chronic exposure to non-eruptive volcanic activity represents a risk factor that can affect the health of the respiratory system of humans inhabiting hydrothermal areas.

Overproduction of TNF-α and lung structural remodelling due to chronic exposure to volcanogenic air pollution

Volcanogenic air pollution studies and their effects on the respiratory system are still outnumbered by studies regarding the effects of anthropogenic air pollution, representing an unknown risk to human population inhabiting volcanic areas worldwide (either eruptive or non-eruptive areas). This study was carried in the archipelago of the Azores- Portugal, in two areas with active volcanism (Village of Furnas and Village of Ribeira Quente) and a reference site (Rabo de Peixe). The hydrothermal volcanism of Furnas volcanic complex is responsible for the release of 1000 t d^-1 of CO₂, H₂S, the radioactive gas - radon, among others. Besides the gaseous emissions, particulate matter and metals (Hg, Cd, Zn, Al, Ni, etc.) are also released into the environment. We tested a hypothesis whether chronic exposure to volcanogenic air pollution causes lung structural remodelling, in the house mouse, Mus musculus, as a bioindicator species. Histopathological evaluations were performed to assess the amount of macrophages, mononuclear leukocyte infiltrate, pulmonary emphysema, and the production of pro-inflammatory cytokine TNF-α. Also, the percentage of collagen and elastin fibers was calculated. Mice chronically exposed to volcanogenic air pollution presented an increased score in the histopathological evaluations for the amount of macrophages, mononuclear leukocyte infiltrate, pulmonary emphysema and production of TNF-α; and also increased percentages of collagen and elastin. For the first time, we demonstrate that non-eruptive active volcanism has a high potential to cause lung structural remodelling. This study also highlights the Mus musculus as a useful bioindicator for future biomonitoring programs in these type of volcanic environments.

CO2 Flux from Volcanic Lakes in the Western Group of the Azores Archipelago (Portugal)

Here, we present the first detailed study on diffuse CO2 degassing in the lakes in the Western Group (Corvo and Flores islands) of the Azores archipelago. This research is of interest in order to determine (1) the overall CO2 emission from such lakes, as volcanic lakes are often underrepresented in the databases of these water bodies, and (2) the diffuse CO2 degassing estimates in active volcanic areas such as the Azores. The lake waters on Corvo and Flores islands are mainly of the Na–Cl type, which is likely caused by the lakes’ sea salt signatures, arising from nearby seawater spraying; however, a few samples show evidence of slight alkali earth metal and bicarbonate enrichments in the lake waters, suggesting a contribution of water–rock interaction. In this study, diffuse CO2 flux measurements were taken using the accumulation chamber method, and statistical analyses utilizing the graphical statistical approach (GSA) and sequential Gaussian simulation (sGs) were conducted on the CO2 flux data, showing that the CO2 flux values measured in these lakes were relatively low (0.0–18.6 g m−2 d−1). The results seem to indicate that there is a single source of CO2 (a biogenic source), which is also supported by the waters’ δ13C isotopic signatures. Significant differences in the final CO2 output values were verified between surveys (e.g., 0.16 t d−1 in R1; 0.32 t d−1 in R2), and these differences are probably associated with the monomictic character of the lakes. CO2 emissions ranged between 0.18 t d−1 (CE1) and 0.50 t d−1 (CW1) for the Corvo lakes and between 0.03 t d−1 (P1) and 0.32 t d−1 (R2) for the seven lakes studied on Flores Island. The presence of a dense macrophyte mass in a few of the lakes appears to enhance the CO2 flux in these lakes.

Soil-Gas Concentrations and Flux Monitoring at the Lacq-Rousse CO2-Geological Storage Pilot Site (French Pyrenean Foreland): From Pre-Injection to Post-Injection

Soil-gas concentrations and flux were measured during 20 separate measurement campaigns at the TOTAL Lacq-Rousse carbon capture and storage (CCS) pilot site, southern France, where 51,000 tons of CO2 were injected in a depleted natural gas field. Baseline data (September 2008 to December 2009) are compared to monitoring data from the injection (March 2010 to March 2013) and post-injection (February 2014 to December 2015) periods. CO2 soil-gas concentrations varied from atmospheric concentrations to more than 16% vol. with 1.4% as median value. Summer data showed high CO2 concentrations in the soil that remained quite high during winter. Median CO2 flux at the soil/atmosphere interface was close to 4.4 cm3·min−1·m−2. Carbon-isotope ratios measured on CO2 in soil gas had a mean value of −23.5 ± 3.1‰, some deviation being due to atmospheric CO2. Comparison between different gas species and the influence of temperature, pressure and soil-water content suggest that gases in near-surface environments are produced locally and naturally, and are unrelated to CO2 ascending from the storage reservoir. Monitoring of CO2 injection and the use of threshold levels is discussed as part of a practical approach considering specific regulations for the Lacq-Rousse CCS pilot experiment and constraints for the site operator.

Hazardous indoor CO2 concentrations in volcanic environments

Carbon dioxide is one of the main soil gases released silently and permanently in diffuse degassing areas, both in volcanic and non-volcanic zones. In the volcanic islands of the Azores (Portugal) several villages are located over diffuse degassing areas. Lethal indoor CO2 concentrations (higher than 10 vol %) were measured in a shelter located at Furnas village, inside the caldera of the quiescent Furnas Volcano (S. Miguel Island). Hazardous CO2 concentrations were detected not only underground, but also at the ground floor level. Multivariate regression analysis was applied to the CO2 and environmental time series recorded between April 2008 and March 2010 at Furnas village. The results show that about 30% of the indoor CO2 variation is explained by environmental variables, namely barometric pressure, soil water content and wind speed. The highest indoor CO2 concentrations were recorded during bad weather conditions, characterized by low barometric pressure together with rainfall periods and high wind speed. In addition to the spike-like changes observed on the CO2 time series, long-term oscillations were also identified and appeared to represent seasonal variations. In fact, indoor CO2 concentrations were higher during winter period when compared to the dry summer months. Considering the permanent emission of CO2 in various volcanic regions of the world, CO2 hazard maps are crucial and need to be accounted by the land-use planners and authorities.

Stationary and transient thermal states of barometric pumping in the access pit of an underground quarry

The transition zone between free and underground atmospheres hosts spectacular phenomena, as demonstrated by temperature measurements performed in the 4.6m diameter and 20m deep vertical access pit of an abandoned underground quarry located in Vincennes, near Paris. In summer, a stable stratification of the atmosphere is maintained, with coherent temperature variations associated with atmospheric pressure changes, with a barometric tide S2 larger than 0.1°C peak to peak. When the winter regime of turbulent cold air avalanches is initiated, stratification with pressure induced signals can be restored transiently in the upper part of the pit, while the lower part remains fully mixed and insensitive to pressure variations. The amplitude of the pressure to temperature transfer function increases with frequency below 5×10(-4)Hz, with values at 3×10(-5)Hz varying from 0.1°C·hPa(-1) at the bottom up to 2°C·hPa(-1) towards the top of the pit. These temperature variations are accounted for by cave breathing, which is pressure induced motion of air amplified by the large volume of the quarry. This understanding is supported by a numerical model including advective heat transport, heat diffusion, and heat exchange with the pit walls. Mean lifetime in the pit is of the order of 9 to 13h, and barometric pumping results in an effective ventilation rate of the quarry of the order of 10(-7)s(-1). This study illustrates the important role of barometric pumping in heat and matter transport between atmosphere and lithosphere. The resulting stationary and transient states, revealed in this pit, are probably a general feature of functioning interface systems, and therefore are an important aspect to consider in problems of contaminant transport, or the preservation of precious heritage such as rare ecosystems or painted caves.

Total (fumarolic + diffuse soil) CO2 output from Furnas volcano

Furnas volcano, in São Miguel island (Azores), being the surface expression of rising hydrothermal steam, is the site of intense carbon dioxide (CO₂) release by diffuse degassing and fumaroles. While the diffusive CO₂ output has long (since the early 1990s) been characterized by soil CO₂ surveys, no information is presently available on the fumarolic CO₂ output. Here, we performed (in August 2014) a study in which soil CO₂ degassing survey was combined for the first time with the measurement of the fumarolic CO₂ flux. The results were achieved by using a GasFinder 2.0 tunable diode laser. Our measurements were performed in two degassing sites at Furnas volcano (Furnas Lake and Furnas Village), with the aim of quantifying the total (fumarolic + soil diffuse) CO₂ output. We show that, within the main degassing (fumarolic) areas, the soil CO₂ flux contribution (9.2 t day^-1) represents a minor (~15 %) fraction of the total CO₂ output (59 t day^-1), which is dominated by the fumaroles (~50 t day^-1). The same fumaroles contribute to ~0.25 t day^-1 of H₂S, based on a fumarole CO₂/H₂S ratio of 150 to 353 (measured with a portable Multi-GAS). However, we also find that the soil CO₂ contribution from a more distal wider degassing structure dominates the total Furnas volcano CO₂ budget, which we evaluate (summing up the CO₂ flux contributions for degassing soils, fumarolic emissions and springs) at ~1030 t day^-1.

Air Pollution by Hydrothermal Volcanism and Human Pulmonary Function

The aim of this study was to assess whether chronic exposure to volcanogenic air pollution by hydrothermal soil diffuse degassing is associated with respiratory defects in humans. This study was carried in the archipelago of the Azores, an area with active volcanism located in the Atlantic Ocean where Eurasian, African, and American lithospheric plates meet. A cross-sectional study was performed on a study group of 146 individuals inhabiting an area where volcanic activity is marked by active fumarolic fields and soil degassing (hydrothermal area) and a reference group of 359 individuals inhabiting an area without these secondary manifestations of volcanism (nonhydrothermal area). Odds ratio (OR) and 95% confidence intervals (CIs) were adjusted for age, gender, fatigue, asthma, and smoking. The OR for restrictive defects and for exacerbation of obstructive defects (COPD) in the hydrothermal area was 4.4 (95% CI 1.78-10.69) and 3.2 (95% CI 1.82-5.58), respectively. Increased prevalence of restrictions and all COPD severity ranks (mild, moderate, and severe) was observed in the population from the hydrothermal area. These findings may assist health officials in advising and keeping up with these populations to prevent and minimize the risk of respiratory diseases.

Volcanogenic pollution and testicular damage in wild mice

Many evidences have surfaced the adverse effects of environmental pollutants on male reproduction. Volcanogenic pollution is understudied, although it is a well-known source of hazardous contaminants. This study aims to assess the effects of chronic exposure to volcanogenic pollution on wild mice testes by studying: (i) diameter of seminiferous tubules; (ii) relative volumetric density of different spermatogenic cells and interstitial space; (iii) damage in the seminiferous tubules and (iv) apoptotic level in the germinal epithelium. The mice from the polluted site showed higher levels of the selected heavy metals than those from the reference site. The mean diameter of seminiferous tubules and the relative volume occupied by spermatozoa and lumen in exposed mice were significantly lower than in the unexposed group. Contrarily, exposed mice showed a significantly higher relative volume occupied by interstitium, as well as, a higher degree of damage and a significantly higher number of apoptotic cells in the germinal epithelium. Results show that secondary manifestations of volcanic activity can pose a serious risk of testicular injury and therefore for male reproduction.

Spring geochemistry in an active volcanic environment (São Miguel, Azores): source and fluxes of inorganic solutes

Mineral waters were monthly sampled in selected springs from Furnas and Fogo trachytic central volcanoes (São Miguel, Azores, Portugal). Water temperatures between 15.1 °C and 90.2 °C, characterize poorly mineralized waters of Na-HCO₃ and Na-HCO₃-Cl types. According to the spring location, two watersheds were selected in each volcano to evaluate solute fluxes and chemical weathering rates (Fogo volcano: Ribeira Grande river - RRG; Furnas volcano: Ribeira Quente river - RRQ). Na, Mg, K and Ca fluxes in groundwater represented 43%, 60%, 46% and 57% of the total (subsurface plus surface fluxes) in RRG, and respectively 43%, 53%, 46% and 49% in RRQ. Average HCO₃ flux is ten times higher in RRQ (130.1 × 10(6) mol/yr) compared to RRG (13.8 × 10(6) mol/yr), reflecting the volcano degassing and the lower ratio between groundwater and river water fluxes. Based on these values, total CO₂-consumption by weathering ranged from 1.5 × 10(6)mol/km(2)/yr (RRG) to 4 × 10(6)mol/km(2)/yr (RRQ). TDS load varied between 3772 t/yr (RRG) and 15388 t/yr (RRQ), and the ratio between values in groundwater and in surface water is respectively equal to 0.72 and 2.04. The associated chemical weathering rates in groundwater were 206 t/km(2)/yr (RRG) and 399 t/km(2)/yr (RRQ). Coupled to river water, these values indicate that total chemical weathering rates are respectively equal to 493 t/km(2)/yr and 594 t/km(2)/yr. A similar approach developed for the entire archipelago showed that the chemical weathering rates due to groundwater are in the range from 33 to 321 t/km(2)/yr, being partially controlled by the age of the islands. Results of the present study point out to the need to consider groundwater solute fluxes due to weathering when establishing geochemical budgets.

Chronic exposure to volcanogenic air pollution as cause of lung injury

Few studies were made regarding the pulmonary effects of exposure to volcanogenic air pollution, representing an unrecognized health risk for humans inhabiting non-eruptive volcanically active areas (10% of world human population). We tested the hypothesis whether chronic exposure to air pollution of volcanogenic origin causes lung injury, using wild mice (Mus musculus) as model. Lung injury was determined using histological morphometric parameters, inflammatory status (InfS) and the amount of black silver deposits (BSD). Mice exposed to volcanogenic air pollution have decreased percentage of alveolar space, alveolar perimeter and lung structural functionality (LSF) ratio and, increased alveolar septal thickness, amount of BSD and InfS. For the first time it is evidenced that non-eruptive active volcanism has a high potential to cause lung injury. This study also highlights the usefulness of M. musculus as bioindicator species, and of the developed biomarker of effect LSF ratio, for future animal and/or human biomonitoring programs.

Living on a volcano's edge: genetic isolation of an extremophile terrestrial metazoan

Communities of organisms inhabiting extreme terrestrial environments provide a unique opportunity to study evolutionary forces that drive population structure and genetic diversity under the combined challenges posed by multiple geogenic stressors. High abundance of an invasive pantropical earthworm (and the absence of indigenous lumbricid species) in the Furnas geothermal field (Sao Miguel Island, Azores) indicates its remarkable tolerance to high soil temperature, exceptionally high carbon dioxide and low oxygen levels, and elevated metal bioavailability, conditions which are lethal for the majority of terrestrial metazoans. Mitochondrial and nuclear markers were used to analyze the relationship between populations living inside and outside the geothermal field. Results showed that Pontoscolex corethrurus (Annelida, Oligochaeta, Glossoscolecidae) to be a genetically heterogeneous complex within the Sao Miguel landscape and is probably differentiated into cryptic species. The population exposed to the hostile soil conditions within the volcanic caldera possesses the lowest within-population mitochondrial diversity but an unexpectedly high degree of nuclear variability with several loci evidencing positive selection, parameters indicative of a genetically unique population only distantly related to conspecifics living outside the caldera. In conclusion, P. corethrurus inhabiting active volcanic soil is a discrete extremophile population that has evolved by tolerating a mixture of non-anthropogenic chemical and physical stressors.

Fluvial geochemistry in São Miguel Island (Azores, Portugal): source and fluxes of inorganic solutes in an active volcanic environment

River water chemistry in two of the major rivers in São Miguel Island (Azores archipelago, Portugal) has been characterized monthly between June 2010 and October 2011 in order to estimate the main geochemical processes that explain water composition and to estimate solute fluxes and the thermal water input to rivers. Both rivers (Ribeira Grande - RRG, and Ribeira Quente - RRQ) drain active trachytic central volcanoes. The number of sampling stations is seven in RRG and six in RRQ. Rivers are mainly slightly acid to basic in nature (pH in the range 5.41-8.70 in RRG and 5.90-8.10 in RRQ) and from the Na-HCO3 and Na-HCO3-Cl water types. In both cases water temperature increases towards the river mouth and median values are slightly higher in Ribeira Quente (15.5-22.4°C) comparing to Ribeira Grande river (15.2-19.7°C). Electrical conductivity suggests poorly mineralized waters (139-456 μS/cm in RRG and 209-402 μS/cm in RRQ, and values increase downstream. Higher solute fluxes are associated to HCO3 and Na, and the total CO2 flux is equal to 3647 t/yr in RRQ and 7546 t/yr in RRG. Mixture with thermal water discharges also influences river water chemistry and in RRQ the contribution to the annual average discharge rate was estimated in 2.96×10(6)m(3)/yr (12.8% of overall discharge rate in the watershed). In RRG thermal water discharges were estimated in 2.4×10(6)m(3)/yr (14.9% of the discharge rate). The minimum total CO2-consumption associated with low-temperature weathering is equal to 0.58×10(6)mol/km(2)/yr in Ribeira Quente river and equal to 0.78×10(6)mol/km(2)/yr in Ribeira Grande river.

Evidence of DNA damage in humans inhabiting a volcanically active environment: a useful tool for biomonitoring

The present study was designed to evaluate whether chronic exposure to a volcanically active environment might result in genotoxic and cytotoxic effects in human oral epithelial cells. A study group of 120 individuals inhabiting a volcanically active environment (exposed group; Furnas village) and a reference group of 122 individuals inhabiting a village without manifestations of volcanic activity (Santo António village) were examined in this study. Individuals from Furnas village inhabit a volcanically active environment marked by several degassing manifestations, including fumarolic fields, thermal and cold CO₂ springs and soil diffuse degassing areas. For each individual, 1000 buccal epithelial cells were analyzed for the frequency of micronucleated cells (MNC) and the frequency of cells with other nuclear anomalies (ONA: pyknosis, karyolysis and karyorrhexis), by using the micronucleus assay. Information on life-style factors and an informed consent were obtained from each participant. The frequencies of MNC and of ONA per 1000 cells in the exposed group (4.3‰ and 23.5‰, respectively) were significantly higher than in the reference group (1.7‰ and 7.7‰, respectively). The risk of having a high frequency of MNC or ONA was 2.4 and 3.1-fold higher in exposed individuals compared to reference group. The analyzed confounding factors (age, gender, smoking status, alcohol consumption, and mouthwash use) did not show any significant association with the frequency of MNC or ONA. The higher risk of DNA damage in individuals inhabiting a volcanically active environment is for the first time clearly highlighted with this biomonitoring study. Given that MNC in oral epithelia are recognized as a predictive biomarker of cancer risk within a population of healthy subjects, these findings could contribute to explain the high incidence rates of lip, oral cavity and pharynx cancers previously referred for Furnas village inhabitants.