Volcanic Ash Research Articles

Productive conservation at the landslide prone area under the threat of rapid land cover changes

Abstract Landslides often occur in the study area as a continuation of the erosion process on very thick soil from a series of volcanic ash deposition during the Tertiary and Quaternary periods. Rapid land cover changes from agricultural land into settlement increase runoff significantly causing accelerated soil erosion. Soil conservation approaches using parameters to reduce surface runoff and soil loss are less acceptable in agricultural society. Soil conservation methods aimed at reducing runoff and soil loss are not widely embraced in agricultural communities, efforts in soil conservation must be economically beneficial. Vegetative-based erosion control is the most suitable option for the agricultural communities. However, there needs to be improvements in terms of plant arrangement that is adapted to the spatial arrangement of slopes and is focused on zones along rills and gullies. Selection of tree species planted for erosion control that have the value of increasing economic income is the key to the success of planned soil and water conservation efforts.

Provenance of Paleogene Strata at Slim Buttes, South Dakota: Implications for post-Laramide Evolution of Western Laurentia

Slim Buttes is a 30 km long by 10 km wide set of buttes containing Paleogene strata in northwest South Dakota. At Reva Gap in northern Slim Buttes, Eocene-Oligocene terrestrial strata of Chadron and Brule Formations of the White River Group unconformably overlie the Paleocene Fort Union Formation. An angular unconformity separates the White River Group from overlying Oligocene and Miocene strata of the Arikaree Group. Using detrital zircon U-Pb ages, we determine the provenance of these rocks as part of a broader synthesis of post-Laramide sedimentation in the Rocky Mountains and western Great Plains. The Chadron Formation age spectrum is dominated by Cretaceous and Proterozoic grains that are interpreted to be locally recycled from the underlying Cretaceous and Paleocene strata. The Brule Formation has a maximum depositional age of ~34 Ma; Paleogene zircons dominate the age spectrum, and a wide variety of older zircons are also present. The Oligocene zircons are interpreted to have been sourced from volcanic systems in the Great Basin to the southwest, while the subsequent proportions of the zircons were derived from a variety of source areas in the Nevadaplano and Rocky Mountain areas to the southwest. Sparse amounts of Archean zircons are thought to represent the burial of Laramide uplifts throughout Wyoming at the time of Brule deposition, making for a regional paleotopography with little relief across the western interior of the United States. The Miocene-age Arikaree Group sand has a maximum depositional age of ~26 Ma and a multimodal detrital zircon age spectrum. The Arikaree Group provenance likely represents continued sourcing in the Great Basin volcanic systems and Nevadaplano, the beginnings of the re-exhumation of Laramide basement uplifts, and subsequent sediment evacuation out of the western interior and into the Gulf of Mexico to the southeast. Our findings indicate that the transport process and detrital zircon provenance signatures of these strata are decoupled, and each have their own independent evolution. The volcanic signature is primarily transported via aeolian processes (i.e. volcanic ash), and the recycled detrital zircon signature is primarily transported via fluvial processes.

Alkali activated materials from Tajogaite volcanic ash (La Palma, Spain): a green recovery after the 2021 eruption

The 2021 Tajogaite eruption was marked by intense pyroclastic fallout that covered a substantial portion of La Palma island, with maximum thicknesses in the central-western part. This, combined with lava flows, resulted in widespread damage to public and private properties. In this study, we investigated if volcanic ash from this eruption could serve as a raw material in the synthesis of alkali activated materials (AAMs) and contribute to the construction of eco-friendly buildings and the restoration of those damaged by the eruption. Volcanic ash-based AAMs were synthesized using NaOH and Na2SiO3 as alkaline solutions and by adding metakaolin to enhance ash reactivity and enable processing at ambient temperatures. Lightweight porous AAMs were also produced using H2O2 and metallic aluminum as foaming agents. Chemical, textural, physical, and mechanical analyses on the final products assessed their suitability as environmentally friendly materials to be used in the reconstruction of the island infrastructure, opening new perspectives on recovery actions that can be undertaken after disastrous eruptions. Of all the islands in the Canary Archipelago, La Palma has experienced the highest number of eruptions (8) in historical times, all of which showing considerable similarity in terms of eruptive mechanisms and composition to the most recent Tajogaite event. Although this study investigated fresh Tajogaite ash, similar perspectives can be envisaged for both other recent eruptions at La Palma and other similar volcanic scenarios worldwide.

Experimental design and multiple response optimization of batch leaching tests of volcanic ashes.

Volcanic eruptions can release large amounts of tephra, lava, and gases, drawing attention due to their magnitude, energy, and impact on life and the environment. Among the most documented and sometimes dramatic effects of volcanic ashes are those linked to the input of diverse elements in the environment, which are released as a consequence of ash weathering. Laboratory studies have been conducted to investigate and predict the environmental input of chemical elements from volcanic ashes. This research paper describes the optimization of batch leaching tests used to investigate the release of ions from ashes collected in the Andes Cordillera after the eruption of the Puyehue volcano in 2011. Chemometric multivariate strategies were employed to evaluate the influence of variables affecting the leaching of volcanic ash. The effects of the main variables, namely contact time, the acidity of the leaching agent, the solid/liquid ratio, the particle size, and the stirring speed, were studied in leaching tests. To determine the optimal conditions for selected metal determinations, we employ Darringer's desirability function, which allows for the simultaneous optimization of the selected responses (element concentrations during the leaching process). Multielemental analysis (Na, Mg, Al, Si, P, Cl, K, Ca, V, Cr, Mn, Fe, Ni, Cu, Zn, Sr, Cd, Hg, Tl, and Pb) was quantified by ICP-MS (inductively coupled plasma-mass spectrometry) following adequate dilution of test leaching. These results established the optimal experimental conditions for leaching volcanic ash. The most significant variables were the solid/liquid ratio and the stirring speed, resulting in two groups of elements with an adequate global desirability function (D) value.

Variable preservation of the 1991 Hudson tephra in small lakes and on land

Volcanic ash (tephra) preserved in terrestrial environments and lake sediments contains information about volcanic processes and can be used to infer eruptive parameters and frequency of past eruptions, contributing to the understanding of volcanic hazards. However, tephra deposits can undergo transformation from their initial fallout sedimentation to being preserved as a tephra layer in the sedimentary record. The process is likely to be different in lakes and in terrestrial (soil) sequences. Here we compare the thickness, mass loading and grain size of tephra layers from the 1991 eruption of Cerro Hudson, Chile, from small lakes and adjacent terrestrial settings to measurements of the tephra made shortly after the eruption. We analysed samples from 35 cores in total from six small lakes (<0.25 km2), located 76 and 109 km from the volcano in two contrasting climatic areas (cool and humid northern site, and warm and dry southern site), and made 73 measurements of tephra thickness and 11 measurements of grain size in adjacent terrestrial areas. The major element geochemistry of our samples confirmed they were from the 1991 Hudson eruption. We found that some of the measured characteristics of the preserved tephra layers were comparable to those recorded in 1991 shortly after initial deposition, but that there was considerable variability within and between locations. This variability was not predictable and lake sediments did not preserve a notably more accurate record of the fallout than terrestrial sites. However, in aggregate the characteristics of the preserved tephra was similar to those recorded at the time of deposition, suggesting that, for palaeotephra research, a sampling strategy involving a wide range of environments is more robust than one that relies on a single sedimentary record or a single type of sedimentary environment.

Detection of Volcanic Ash Using Goes-16 Satellite Imagery: Case Study of Popocatépetl Volcano, Mexico

Objective: The objective of this study is to investigate the accuracy of volcanic ash detection using satellite imagery, to improve existing monitoring tools to adapt them to the Popocatépetl volcano in Mexico. Theoretical Framework: Volcanic ash detection via remote sensing employs Pavolonis' algorithms that compare radiances in the thermal and mid-infrared spectrum. This approach differentiates ash from clouds and water vapor by leveraging its differential absorption. Satellites such as GOES-16, which capture multispectral data, optimize the continuous detection and monitoring of ash dispersion, even in areas of low concentration. Method: Three volcanic ash detection algorithms were compared using images from the Popocatépetl eruption event on May 21, 2023: two developed by Pavolonis, which combine thermal and mid-infrared bands, and a third, a spectral adaptation designed to enhance precision at the edges of the ash cloud, tailored to the study area. Results were validated with an RGB ash image provided by NOAA. Results and Discussion: Pavolonis' algorithms provided a solid foundation for general detection, but the third algorithm, specifically designed for this study, significantly improved edge detection where classification conditions are more complex. This improvement was reflected in a higher agreement with the RGB ash image used as a reference. However, limitations related to atmospheric interference were identified, which require further adjustments in low ash concentration scenarios. Research Implications: The findings of this research have significant practical and theoretical implications for volcanic risk management and environmental protection. Enhanced accuracy in volcanic ash detection can optimize monitoring and early warning strategies, reducing risks to public health and infrastructure. Originality/Value: This study contributes to the literature by introducing a specific spectral adaptation to improve edge detection of volcanic ash, a novel approach not previously addressed. The research's relevance lies in its ability to refine monitoring methodology, providing more effective tools for volcanic risk management and offering a model applicable to other areas facing similar remote sensing challenges.

Valorization and investigation of volcanic ash as an aggregate building brick component

Abstract The devastating series of Taal volcanic eruptions from 2020 to 2022 covered several locations in the Philippines under a thick layer of ashes, destroying properties and halting business operations. In response, the Biñan City Government in Laguna, Philippines, proposed the development of eco-friendly bricks by leveraging the pervasive amounts of spewed volcanic ash as part of its solid waste management program. The materials recovery facility of the city produced several brick blends of combined Taal volcanic ash, cement mortar, and plastic waste materials. This study investigates the potential of Taal volcanic ash as an aggregate building brick component by measuring the compressive strength of the formulated bricks. With different blends of aggregate components, the bricks were tested for their durability based on the ASTM C67/C67M-20 standard after curing between 15 to 30 days. Per the ASTM C62-17 standard, all brick blends that were cured for 30 days including those with volcanic ash and plastic waste as aggregate components fall under the negligible weathering grade. This indicates that these bricks will be durable in building and structural applications where the average compressive strength requirement for bricks is at least 10.3 MPa. A regression model was also fitted with an adjusted r 2 value of 0.9413 and a p-value of < 2.2 × 10−16 using the experimental data.

Particle Concentrations and Sizes for the Onset of Settling‐Driven Gravitational Instabilities: Experimental Validation and Application to Volcanic Ash Clouds

AbstractSettling‐driven gravitational instabilities (SDGIs) can form at the base of buoyant particle‐laden suspensions, modulating particle sedimentation in various settings such as meteorological and volcanic clouds, fluvial plumes, magma chambers, submarine hydrothermal plumes, or industrial emissions. These instabilities result in the formation of rapidly descending currents called ‘fingers’ within which fine particles settle faster collectively than individually. This study investigates SDGI triggering conditions underneath volcanic ash clouds through analogue experiments considering sedimentation from aqueous particle suspensions. We confirm that the conditions for which SDGIs develop are controlled by two dimensionless numbers: Bf (ratio of the characteristic finger velocity to the individual particle settling velocity); and Bi (ratio of timescale for individual particle settling to that for collective settling controlled by inertial drag). SDGIs are triggered for values of Bf and Bi > 1 for which particles are fully coupled with the flow within fingers. Using these parameters, we produce a regime diagram for the 2010 eruption of Eyjafjallajökull (Iceland) that describes particle settling as a function of particle concentration and size. More studies are needed to produce a general regime diagram accounting for the evolution of SDGIs properties with eruption and atmospheric parameters. Nonetheless, our study confirms that fingers affect sedimentation from volcanic clouds with high ash volume fractions above 10−6 vol.%. Our validation of criteria predicting the onset of fingers due to SDGIs constitutes a step forward toward the incorporation of these collective settling processes in volcanic ash transport and dispersion models.

Exploring the comprehensive performance of lotus-leaf-inspired biomimetic NdYbZr2O7 thermal barrier coatings

Two micro-nano structural NdYbZr2O7 thermal barrier coatings (TBCs) inspired by lotus leaf were fabricated by ultrafast laser direct writing technology, which are defined as coating A and B respectively. The biomimetic coatings exhibit an outstanding volcanic ash repellence within a short-term period (1200 °C/10 min), while this performance dramatically deteriorates with time due to destruction of micro-conoids caused by the chemical reaction rather than the high-temperature sintering of nanoparticles. Additionally, this chemical reaction is responsible for the formation of dense reaction layer composed of c-ZrO2 and apatite grains in the sides of conoids, which effectively protects the underneath coating substrate from the infiltration and corrosion of molten volcanic ash. Thermal conductivity of these two laser-ablated coatings increases approximately 30 % than that of as-sprayed counterpart because of both the increase in dispersity of interface discontinuity and the decrease in coating thickness. During the wear process, the conoids are susceptible to abrupt fracture in the presence of load stress, as well as the initial deposited nanoparticles, resulting in the reduce of wear resistance against hard debris.

Illitization of smectite influenced by chemical weathering and its potential control of anatase formation in altered volcanic ashes

Abstract Illitization of smectite in sedimentary systems, a process akin to “reverse weathering,” is a diagenetic process that has significant implications for sediment paragenesis and hydrocarbon exploration. However, the potential influence of chemical weathering on the illitization of smectite and its possible control of the neogenesis of titanium (Ti)-oxides remain unclear. Altered volcanic tephra layers (i.e., K-bentonites) characterized by an interstratified illite-smectite (I-S) clay mineralogy serve as an excellent medium to investigate the illitization of smectite. In this study, we first investigated the fine structure of clay minerals and in situ nano-mineralogy of Ti-bearing minerals from altered volcanic ashes and then undertook a meta-analysis of geochemical compositional data for bentonites spanning a wide range of ages and depositional environments globally. We found that Ti mainly occurs as discrete micrometer-scale magmatic srilankite and nanoscale authigenic anatase crystals. During the weathering process, the magmatic srilankite partly dissolved under acidic conditions, resulting in a local buildup of Ti in porewaters. The I-S displays a platy habit and curved edges and is found closely associated with anatase crystals under TEM. Our compilation results combined with microscopic evidence suggest that chemical weathering may potentially promote the illitization reaction by changing the chemical composition of the fluids through increased terrestrial inputs and by creating larger pore spaces through the decomposition of weatherable components. Positive correlations between K and Ti are especially common in (K-)bentonites that are dominated by I-S, suggesting that I-S can adsorb Ti during the weathering process and provide a suitable site for the nucleation of anatase. Our study highlights the role of chemical weathering in the illitization of smectite and their combined effect on the formation of Ti-oxides.

Spread or Splash: The Ubiquitous Role of Droplets in Mafic Explosive Eruptions

AbstractMagma fragmentation is an essential process driving explosive volcanic eruptions, generating a distribution of pyroclasts with characteristic shape and grain size. These characteristics are often used to inform on the energetics of magma fragmentation and the associated eruption style and intensity. However, a portion of these pyroclasts, droplets when still in the molten state, are likely to be generated through impact mechanisms (i.e., collisions), and subsequent secondary fragmentation (i.e., splashing). Here, we successfully apply and dynamically scale concepts and findings of liquid droplet impacts in engineering to magma fragmentation processes in volcanology. We compile and model physical data for two mafic melt compositions (kimberlite and basalt) and use specific eruption examples from Igwisi Hills, Kīlauea and Stromboli volcanoes to define composition‐specific impact dynamics. Pyroclast impact dynamics have a direct control on in‐conduit processes, eruption dynamics, and ash dispersal. For low viscosity mafic melts such as kimberlite and basalt, pyroclast impacts can lead to both splash and deposition on the conduit wall, resulting either in conduit clearing or conduit narrowing, respectively. In both cases, shifting the impact regime toward surface deposition will lead to an inexorable decay in explosiveness, potentially switching the eruption style to effusive behavior. This has direct consequences for the transport of volcanic ash at the surface and inferring magma fragmentation processes (e.g., energies) from the depositional record.

Effects of a recent volcanic eruption on the isolated population of the iconic red-billed chough in La Palma, Canary Islands.

The effects of volcanic eruptions on ecosystems, particularly on oceanic islands, have been widely studied because of their important role in land formation, climate patterns and biological processes. Although these phenomena can lead to habitat loss, population decline and even species extinction, their effects on isolated populations, especially vertebrates, are not fully understood due to the paucity of pre-eruption data and in situ observations. Here, we assess the impact of the recent eruption of the Tajogaite volcano in La Palma, Canary Islands, on a unique population of red-billed choughs (Pyrrhocorax pyrrhocorax), an emblematic bird species that symbolises the natural heritage of the island. Pre- and post-eruption surveys showed that the eruption did not significantly affect the overall size or distribution of the population, although the number of choughs decreased after the eruption in the northern and central roosts, and increased in the southern ones. Although the eruption resulted in the release of toxic gases and ash, the observed changes in chough distribution and numbers could be attributed to environmental variability and the use of different foraging areas by individuals rather than direct effects of the volcano. The high mobility of choughs may have allowed them to avoid the negative effects of the volcano in the immediate aftermath of the eruption. Future studies are recommended to assess the long-term effects of volcanic ash on feeding habitats and the possible accumulation of contaminants, such as heavy metals, in the food chain. This will allow not only to monitor the presence of these compounds in ecosystems, but also to understand the response of this species to environmental changes and ensure its conservation.

Upper Miocene volcanic ash layers from central Italy: tracking down the volcanic source

Upper Miocene volcanic ash layers from central Italy: tracking down the volcanic source

First U-Pb (CA-ID-TIMS) Dating of the Uppermost Permian Coal Interval in the Minusinsk Coal Basin (Siberia, Russia) Using Zircon Grains from Volcanic Ashfalls

This study presents the first U-Pb (CA-ID-TIMS) radioisotopic dating of zircon grains extracted from tonsteins within the uppermost Permian coal interval of the Minusinsk Coal Basin (Siberia, Russia). Petrographic, structural, and mineralogical analyses confirm the volcanic ash origin of the tonsteins. The parent pyroclastic materials are identified as rhyolite–pantellerite for tonstein I-22 and dacite–rhyodacite for tonstein I-12. Morphological analysis of zircon crystals, along with cathodoluminescence and melt inclusion studies, confirms their volcanic origin and crystallisation temperatures of 700–900 °C. New radioisotopic dates of 261.4 ± 0.7 Ma and 261.3 ± 0.4 Ma clarify the age of the Izykh Formation, enabling its direct correlation with the Capitanian Stage of the International Chronostratigraphic Chart. The results emphasise the possible discontinuity of the coal-bearing succession of Siberian palaeocontinent and highlight the potential for further stratigraphic refinement through continued radioisotopic dating of tonsteins.

Behaviour of ionic herbicides in different forestry soils derived from volcanic ash

Background: Weed control has been one of the most significant factors in forest establishment practices that can improve biomass production, and herbicides represent the most effective and convenient way to control weeds. The environmental concern about herbicides in this industry is because the herbicide-treated area is often located near water reservoirs or areas where rivers and creeks originate. This study aimed to determine the adsorption and degradation behaviours of seven ionic herbicides used in forestry production in five Chilean forestry soils and their relation to the leaching and to generate information to validate environmental predictive models. Methods: Adsorption and degradation of ionisable herbicides such as simazine, terbuthylazine, hexazinone, metsulfuron-methyl, indaziflam, flazasulfuron and glyphosate were studied in Andisol, Ultisol, Inceptisol, Entisol and Alfisol forestry soils, to be related to their leaching in 100-cm high and 11-cm diameter soil disturbed lysimeters. Herbicides were quantified using high-pressure liquid chromatography and gas chromatography. Relationships between soil physicochemical properties, herbicide adsorption and degradation, and herbicide leaching were determined. Results: In decreasing order, the herbicides were mobile in Entisol>Alfisol>Ultisol>Inceptisol>Andisol soils. On the other hand, the more leachable herbicides, from high to low, were: hexazinone, metsulfuron-methyl, simazine, glyphosate, terbuthylazine, flazasulfuron and indaziflam. The last two herbicides were not detected below 60 cm soil depth. In general, the maximum soil depth herbicide reached and the percentage mass leached up to 90 cm soil depth were inversely related to soil adsorption (1/Kd), soil porosity, humidity, silt, aluminium, and calcium soil content. Herbicide degradations were generally faster than referential published values. Conclusions: The environmental coefficients of ionic herbicides were more related to soil properties than their physicochemical properties. Persistence of herbicides in soil was smaller than that commonly reported in other studies or international databases and soil adsorption averages were generally higher than international reference values. The stronger relationship between ionic herbicide behaviour and forestry soil properties endorses the requirement to determine the environmental herbicides parameters in situ, avoiding using parameters estimated in other soils.

Corrosion resistance of multicomponent disilicate (Ho0.2Er0.2Tm0.2Yb0.2Lu0.2)2Si2O7 against CMAS and volcanic ash

With the increasing operating temperature of gas turbine engines, calcium-magnesium-aluminosilicate (CMAS) poses a serious threat on environmental barrier coatings (EBCs) applied on hot-sections of aero-engines. Here, we have synthesized a novel multicomponent disilicate—(Ho0.2Er0.2Tm0.2Yb0.2Lu0.2)2Si2O7 (brief to (5RE0.2)2Si2O7), and comparatively studied its performance in the presence of synthesized CMAS and natural volcanic ash at 1400ºC. In comparison with Yb2Si2O7, (5RE0.2)2Si2O7 has a shorter Si-O bond length and a larger RE-O bond length because of the larger average RE3+ radius. After CMAS corrosion, some apatite grains precipitate at the CMAS/(5RE0.2)2Si2O7 interface to develop a loose reaction layer, exhibiting a higher corrosion resistance than Yb2Si2O7. Meanwhile, the consumption of CaO and release of SiO2 during the chemical reaction process increase the viscosity of CMAS to some extent and thus weaken its infiltration propensity. For the volcanic ash case, it directly infiltrates into the interior of (5RE0.2)2Si2O7 along grain boundaries without any reaction due to the relatively low CaO content, exhibiting a more serious attacking behavior. In addition, (5RE0.2)2Si2O7 effectively increases the contact angle of molten volcanic ash due to its lower surface energy. These finds here provide a better understanding for the design and application of next-generation EBC material.

Assessment of the Effects of ZnO and CuO Engineered Nanoparticles on Physicochemical Properties of Volcanic Ash Soil and Phosphorus Availability

The presence of engineered nanoparticles (ENPs) in soil systems can modify their properties and the availability of nutrients. This study evaluated the effect of 1% CuO or ZnO ENPs on the physicochemical properties and on the phosphorus (P) adsorption–desorption processes of a volcanic ash soil (Lautaro; LAU). The dynamics of P were conducted through kinetic and isotherm batch experiments. The results showed that LAU soil with 1% CuO or ZnO ENPs increased pHH2O (from 5.67 to 6.03 and 6.82, respectively), electrical conductivity (from 0.119 to 0.143 and 0.150 dS m−1, respectively), Zn availability (597.7 times higher for LAU with 1% ZnO ENPs in relation to soil without ENPs), and Cu availability (41.8 times higher for LAU with 1% CuO ENPs in relation to soil without ENPs). Moreover, the presence of ENPs decreased Brunauer, Emmett, and Teller specific surface area. The adsorption kinetic studies of P on LAU soil without and with 1% ENPs fitted well to the Elovich model (r2 ≥ 0.923), which indicated a chemiadsorption mechanism, whereas the adsorption isotherms were described by Langmuir–Freundlich model (r2 ≥ 0.939). The desorption percentage was LAU > LAU + 1% CuO–ENPs > LAU + 1% ZnO–ENPs, demonstrating an increased stability of the P–soil surface binding with 1% ENPs. Co–existing NO3−, SeO42−, and SO42− anions did not generate a steric hindrance between P and LAU soil binding. Finally, both ENPs could alter the quality of the soil due to changes in their physicochemical properties and decrease the availability of P in volcanic ash soils.

Design, preparation, and performance of marine resource-based alkali-activated cementitious materials

The construction of islands and reefs and marine engineering cannot depend on cementitious materials, and how to utilize marine resources to prepare cementitious materials is the key to realizing the convenient construction of marine engineering. In this paper, starting from the necessary composition for the formation of gels, the effects of different activation methods on their activities were investigated by utilizing coral and diatomite as calcium and silicon sources, respectively. The study results show that using calcined coral to activate calcined diatomite resulted in a 28 days strength of up to 2.89 MPa, but it was not processable. The precursor with volcanic ash can be prepared by co-calcining coral and diatomite under lower temperature conditions, and its calcination temperature needs to be no less than 800 °C. In addition, characterization by XRD, FTIR, SEM and BET showed that increasing the calcination temperature helps to form more active substances with volcanic ash, such as CaO, CaSiO3, and Ca2SiO4, which can improve the compressive strength of alkali-activated materials prepared from them. The highest strength growth rate of 3.03 % and 28 days compressive strength of 10.80 MPa were obtained when the co-calcined temperature was 850 °C. The results of this study can provide some reference for the development of marine resource-based cementitious materials.

Respiratory and physical health consequences in older adults in a high-risk volcanic area: Comparison of two rural villages

Introduction Volcanism is an important natural producer of pollution that impacts health and the quality of the environment. Lung changes caused by exposure to volcanoes have been previously studied. However, limited information exists regarding the effects of prolonged exposure to volcanic compounds. So, this study aimed to analyze the pulmonary effects and stress tolerance in older adults for chronic exposure to the volcanic ashes of the Galeras volcano. Methods A descriptive cross-sectional study of association included rural inhabitants aged over 60 years from Genoy, a village located in a high volcanic hazard zone of Galeras volcano, 2603 meters above sea level. Those in this group, called exposed, were contrasted with a sample of El Encano inhabitants with similar socioeconomic and cultural characteristics. Both villages belong to the rural area of San Juan de Pasto in Colombia. Results It was found that of 31 exposed participants, 18 had obstructive alteration, and in the control group, it was found that of 31 subjects, 6 presented this alteration. The difference between the two groups was significant (p<0.001). A similar situation occurred with distal airway obstruction assessed with the forced expiratory flow of 25–75%. No significant differences were found in restrictive alteration between the exposed and unexposed groups. Conclusion Chronic exposure to volcanic compounds has generated obstructive changes in the population, and these changes were greater in number and severity than those in the control group of unexposed people.

Crystal Structure, Microstructure, and Dielectric and Electrical Properties of Ceramic Material Prepared Using Volcanic Ash

In the present work, the electrical and dielectric properties of ceramic samples prepared from volcanic ash were investigated. For this purpose, ceramic samples were prepared using milled volcanic ash with a binder material at a sintering temperature of 950 °C for 2 h. The chemical content of the milled volcanic ash was investigated using XRF. Differential thermal analysis and thermogravimetry were performed to determine the firing conditions. The crystalline phases and microstructures of the ceramic samples were investigated using XRD and SEM, respectively. Finally, the electrical and dielectric properties of the obtained samples were evaluated at a frequency ranging from 1 × 102 to 4 × 106 Hz and temperatures ranging from room temperature to 800 °C. The XRD results revealed that the ceramic samples contained three main phases: albite, hematite, and augite. Moreover, the microstructures of the samples exhibited a large crystal size with a dense surface. The conductivities and dielectric constants of the samples remained stable up to 500 °C. The real and imaginary parts of the dielectric constant decreased with an increase in frequency and increased with an increase in temperature. The results indicated that ceramics based on volcanic ash are promising for use in technological applications such as high-voltage power insulators.