Fumaroles Research Articles

Natural mineral spring water (hora) and surrounding soils in southwestern Ethiopia: farmers’ feeding practices and their perception about its nutritional roles on animal performance

Natural mineral water (termed hora in Afan Oromo) and surrounding soils are the most important source of mineral supplement traditionally used for livestock in many parts of Ethiopia. However, limited information exists on feeding practices and the impact of hora on animal performance. Thus, the present study aimed to assess farmers' feeding practices and perceptions about the role of hora and surrounding soils on animal performance. Data were collected from 385 households in four districts (Bedele, Dabo, Gechi and Boracha) through face-to-face interviews using a semi-structured questionnaire with the help of the KoboCollect application. Data were analyzed using SPSS version 26. The majority (72.3 %) of respondents reported hora as an important source of mineral supplement for livestock. About 78.1 % of respondents in Boracha routinely supplement their animals compared with farmers from other districts. Large ruminants were given first priority in supplementation with hora compared to other livestock. Interviewed farmers trekked their animals a distance of 6.5 ± 0.2 km to access hora twice a year during the dry season. The majority of the farmers (68.1 %) believed that hora supplementation improved animal performance, while 35.1 % noted negative impacts such as abortions, birth defects, delayed puberty, decreased conception rates and paralysis due to excessive consumption. This study underscores the perceived importance of hora as a natural source of mineral supplementation for livestock health and productivity. It emphasizes the need for improved management and conservation practices to ensure sustainable utilisation and mitigate negative impacts associated with excessive consumption. Moreover, to validate local farmers' perceptions regarding the importance of hora mineral water in animal nutrition and health, further research is needed to determine mineral composition of hora and livestock responses under controlled feeding trials.

Estimating emission flux of H2S from fumarolic fields using vertical sensor array system

The emission flux of volatiles from each fumarolic field in volcanic and geothermal areas can be used to evaluate the current state of magmatic activity and predict its future trends. The emission flux of SO2 has been quantified in many fumarolic fields using remote sensing techniques, such as differential optical absorption spectroscopy (DOAS). However, most of these remote sensing techniques are inapplicable to fumarolic fields emitting volatiles depleted in SO2 to which most of the geothermal fields are classified. In this study, we developed a vertical sensor array system to quantify the emission flux of H2S from each fumarolic field by integrating the cross-sectional distributions of H2S concentrations in the volcanic plume using the vertical sensor array system. In Iwo-yama of the Kirishima volcanic complex, the cross-sectional distribution of H2S concentrations was determined using the walking traverse method by moving the vertical sensor array system in the plume perpendicular to the direction of plume transport. The emission flux of SO2 (2.2 ± 0.4 ton SO2/day) was estimated from that of H2S using the walking traverse method (2.6 ± 0.5 ton H2S/day) and the molar ratio of the plume (SO2/H2S=0.45) corresponds well with that estimated optically by JMA. We concluded that the emission flux quantified using the vertical sensor array system was reliable. In the Oyunuma pond in the Kuttara volcano, the emission flux of H2S was quantified as 2.0 ton H2S/day through the fixed point method, wherein the vertical sensor array system was fixed in one point, whereas the cross sectional distribution of H2S in the plume was estimated using the natural variation in wind direction. The topography is often irregular and wind direction is variable in most fumarolic fields; thus, in general, the fixed point method should be more suitable to determine the emission flux of H2S from fumarolic fields, wherein H2S occupies a major portion of the total sulfur emission.

Monitoring hydrothermal fumaroles in the Azores archipelago - Applications and sources of analytical uncertainties

The Azores archipelago is located in the North Atlantic Ocean and is formed by nine volcanic islands. Present-day volcanic activity in the archipelago comprises not only seismic swarms and episodes of ground deformation in some volcanoes, but also hydrothermal gas manifestations. The main fumaroles are associated with central quiescent volcanoes and have been sampled in the past decade through the Giggenbach methodology. Analysis of the fumarolic fluids from four volcanic systems in São Miguel, Terceira, and Graciosa islands are displayed for the period between July 2015 and February 2023. No significant changes have been observed both on the selected gas ratios (CO2/CH4, H2/CH4, He/CH4, He/CO2, and H2/Ar), and on the equilibrium temperatures estimated for the reservoirs feeding the fumaroles using the H2/Ar gas geothermometer, what is in agreement with the dormant state of activity of the studied volcanic systems. Equilibrium temperatures ranging between 223 °C and 262 °C are estimated for Fogo and Furnas fumarolic fields (São Miguel Island), and an average equilibrium temperature of 254 °C is inferred for Terceira fumaroles. This study also suggests a procedure based on established guidelines to evaluate the analytical uncertainties of the methodologies associated with the Giggenbach sampling strategy. Comparison of the analytical uncertainties with the overall data variation (including additional natural variations and sampling uncertainty), shows that the analytical uncertainties are not the limiting factor for the interpretation of the survey results.

Geochemical Evolution in Historical Time of Thermal Mineral Springs at Campetti Southwest (Veii, Central Italy) through Geoarcheological Investigation

A multidisciplinary study, involving hydrogeological, geochemical, and mineralogical analyses, was conducted to define the evolution of thermal mineral springs in the Sabatini Volcanic District (SVD) (Central Italy) in a historic period. The outcomes were integrated with the archeological findings to improve the knowledge of the evolution of Veii, a settlement established since the Iron Age and later expanded by Etruscans and Romans. During the archeological excavations, water-related buildings were identified, especially at the Campetti Southwest site in the Veii settlement. Votive inscriptions also suggest the presence of buildings linked to sacred waters, even if a clear definition of the source and type of water is missing. In the SVD, some low-flow thermal mineral springs are present as a result of the mixing of thermal and CO2-rich groundwater from the deep carbonate aquifer and the cold, shallow volcanic aquifer. Mineralogical and chemical analyses characterized the travertine and Fe-hydroxide deposits on Roman tanks and walls in Campetti Southwest and in a nearby ancient Roman bath along the Valchetta River. These deposits showed different relative concentrations of sedimentary and volcanic-related elements, testifying a geochemical evolution of the groundwater mixing and the presence of a paleothermal mineral spring in Campetti Southwest.

Рекомендации по развитию горного туризма с учетом особенностей региона

Introduction. Currently, one of the most popular destinations among tourists is mountain tourism. Moreover the territory of the North Caucasus is of particular interest due to its unique landscape, the presence of mineral springs and other natural resources, as well as cultural attractions. Considering the rich tourism potential of this region, ethno-cultural, rural, environmental and adventure tourism is successfully developing. As a separate relatively new direction, we will highlight geological tourism, in which travelers not only enjoy nature, but also gain new knowledge about the structure of the Earth, study the relief, rocks, soil and vegetation. The mountainous terrain promotes the active development of rock climbing and the hikes’ organization with various levels of difficulty. Thus, today the North Caucasus is open to the tourism’s development of various types and deservedly enjoys increased demand for tourism services. However its potential is not fully exploited. The issues of transport infrastructure and tourist awareness about attractions and constantly updated routes have not been sufficiently developed. This is especially true for spontaneous tourists who prefer to act independently. Materials and methods. When conducting the research, general logical methods, a systematic approach, and content analysis of scientific literature on the issues under study were used. In order to study individual issues in more detail, a survey was conducted. A total of 279 respondents were interviewed. The questionnaire was sent out through the digital tool “Yandex.Forms” and includes answers from respondents living in the Central, Northwestern, Southern, Volga and Ural federal districts. Results. The North Caucasus is considered one of the popular tourist regions, attracting a significant number of tourists for many decades, not only our compatriots, but also travelers from all over the world. Of particular interest is the tourism and recreational potential of the Republic of North Ossetia-Alania, which is rich in natural resources and cultural and historical heritage. The study revealed interest in solving the issue of further strengthening the tourism potential of the region on the part of not only the main participants, which are buyers and services’ sellers, but also representatives of the local administration and the state. For example, the Strategy for the development of tourism in the North Caucasus federal district until 2035 involves the formation of measures to ensure the tourists’ safety and the operation of tourist infrastructure, and improve the services’ quality. The results of the survey made it possible to determine that, in modern realities, many tourists prefer to organize their holidays on their own. It has also been established that a significant part of these tourists are young people under the age of 20. Discussion. Analysis of the data obtained by the authors during desk and field research allowed us to determine that one of the ways to increase the region’s attractiveness for tourists, especially spontaneous ones, is the task of timely informing them about new attractions and routes. This task must be solved comprehensively, through the interaction of state regulatory authorities, local authorities and travel companies. To do this, when assessing the natural and recreational resources of the region, it is recommended to calculate the integral indicator taking into account constantly updated operational data. Conclusions. The authors draw the following conclusion. In order to ensure the safety of tourists and increase the attractiveness of the region, it is necessary to develop an information resource that displays the maximum number of attractions in the North Caucasus, which will contribute to the construction of optimal and also the most interesting routes. It is proposed to create and place in the public domain an interactive map that will allow receiving constantly updated data, which will increase the interest of potential travelers and ensure the full disclosure of the potential for a particular region. Resume. In order to promote the region on the tourism services market in the era of the development of information technology and youth activity, we consider it advisable to provide access to tourist sites online, which will attract an additional flow of visitors. The interactive map must include the location of cultural and historical monuments, as well as types of tourism implemented in a certain area. Suggestions for practical applications and future research directions. The proposed recommendations will make it possible to regulate tourist flows, increasing the attractiveness of the region, and provide such services at a level that best satisfies the needs of modern society.

Water quality and environmental wellness of mineral springs in the Uvs province based on diatom studies

Fifty-eight diatom species belonging to 34 genera, 20 families, 11 orders, and one class are identified in the diatom survey of mineral springs near Uvs and Khyargas lakes in northwest Mongolia. The water quality of the mineral springs of Uvs Lake is fresh, and the mineral spring belonging to Khyargas Lake is fresh to brackish based on the diatom community. The environmental well-being of those springs is 78.5-83.5. Conservation management has to be based on aquatic diversity studies to restore these springs to nature. Conservation management of springs based on algae communities is an issue that is being raised for the first time in Mongolia.

Hydrogeochemical conditions of submarine and terrestrial karst sulfur springs in the Northern Adriatic

Submarine springs near Izola, in the Northern Adriatic Sea, appear in funnel-shaped depressions and smell strongly of sulfur. Along the Mediterranean coast there are many submarine karst springs containing brackish or fresh water, but submarine sulfur springs are not particularly common. Three submarine sulfur springs and one terrestrial sulfur spring were investigated to better understand the water properties, water–rock interaction within the aquifer, and to explore the origin of the spring water. Groundwater and seawater samples were also collected for comparison. Based on the geological setting, physicochemical parameters, hydrogeochemical data, and stable isotope data (δ18O, δ2H, δ13CDIC, δ34SSO4, δ18OSO4), we can affirm that (1) the large concentration of seawater in the submarine springs samples is due to sampling challenges; (2) springs recharge from precipitation where confined karst aquifers outcrop; (3) deep water circulation is indicated; (4) redox conditions can provide a suitable environment for bacterial reduction of the marine or organic sulfate to the odorous H2S; (5) geological data suggests that the coals beneath the alveolinic-nummulitic limestones are the source of sulfur. A multi-parameter and interdisciplinary approach has proven important in assessing submarine sulfur springs affected by seawater input.

An Autonomous Thermal Camera System for Monitoring Fumarole Activity.

The Kenyan part of the East African Rift System hosts several geothermal fields for energy production. Changes in the extraction rate of geothermal fluids and the amount of water re-injected into the system affect reservoir pressure and production capacity over time. Understanding the balance of production, natural processes and the response of the geothermal system requires long-term monitoring. The presence of a geothermal system at depth is often accompanied by surface manifestations, such as hot water springs and fumaroles, which have the potential for monitoring subsurface activity. Two thermal camera timelapse systems were developed and installed as part of a multi-sensor observatory in Kenya to capture fumarole activity over time. These cameras are an aggregation of a camera unit, a control unit, and a battery charged by a solar panel, and they monitor fumarole activity on an hourly basis, with a deep sleep of the system in between recordings. The article describes the choice of hardware and software, presents the data that the cameras acquire, and discusses the system's performance and possible improvement points.

Degradation of the 2014–2015 Holuhraun vent-proximal edifice in Iceland

AbstractThe earliest stages of volcanic vent degradation are rarely measured, leaving a gap in the knowledge that informs landform degradation models of cinder cones and other monogenetic vent structures. We documented the initial degradation of a 500-m-long spatter rampart at the primary vent of the 2014–2015 Holuhraun eruption in northern Iceland with high-resolution topographic change maps derived from terrestrial laser scanning (TLS) and photogrammetric surveys using an unoccupied aircraft system (UAS). Topographic differencing shows a total negative volume change of 42,637 m3, and a total positive volume change (basal deposition) of 10,304 m3 (primarily as deposition at the base of steeply sloping surfaces). Two distinct styles of volume changes were observed on the interior and exterior of the spatter rampart. Material on the interior of the vent was removed from oversteepened slopes by discrete rockfalls, while diffusive processes were qualitatively evident on the exterior slopes. We propose a novel conceptual landform evolution model for spatter ramparts that combines rockfall processes on the interior walls, diffusive gravitational sliding on the exterior slopes, and incorporates cooling contraction and compaction over the entire edifice to describe the observed modes of topographic change during the onset of degradation. Potential hazards at fresh spatter ramparts are rockfalls at high slope areas of the vent interior walls where contacts between spatter clasts are prone to weakening by fumarolic activity, weathering, and settling. To capture such hazards, our data suggest a cadence for monitoring changes yearly for the first few years post-eruption, and at longer intervals thereafter.

Ground deformations associated with an overpressurized hydrothermal systems at Azuma volcano (Japan) revealed by InSAR data

Inflations at active volcanoes are indicators of overpressure in the subsurface, which is known to be a phenomenon that precedes eruptions. Volcanic overpressure is induced by the injection of magmatic fluids, accumulated magma, or heat supply from greater depths. Azuma volcano (Japan) has experienced several episodes of volcanic unrest with increases in seismicity at the depth of the hydrothermal system, implying a potential increase in phreatic eruptions. The time series of interferometric synthetic aperture radar data, associated with the unrest episodes occurring in 2014–2015 and 2018–2019, revealed spatiotemporal variations of inflation episodes, centered around Oana crater, the most active fumarole of Azuma volcano. The modeled best-fit geometry of the elongated pressure source for the local deformation has the same dip as the overlying topographic slope direction and angle around Oana crater, suggesting the existence of topography-correlated layered structures within the hydrothermal system. In contrast, the broader deformation associated with the 2014–2015 unrest was explained by the overpressure of a horizontal flat source at 360–1500 m below sea level, showing the similar depth of the top as the conductive low-resistivity or low-viscosity body suggested by previous studies. The unrest episodes were thus interpreted as resulting mainly from the supply of magmatic fluids, or the transfer of heat from greater depths. Our study helps in understanding the shallow structure of this volcanic system and contributes to evaluating the potential for forthcoming eruptions in Azuma volcano.Graphical

A critical evaluation of the role of a geothermal system in lithium enrichment of brines in the salt flats: A case study from Laguna Verde in the Atacama Region of Chile

The association between geothermal fluids and lithium-rich brines in salt flats has been evaluated in a unique natural laboratory in the Chilean Andes. The area encompasses Laguna Verde (LV), a hypersaline lake, and a salt flat (salar) within a closed basin surrounded by volcanoes. The predominant lithology consists of andesitic-dacitic rocks, with limited occurrences of rhyolitic rocks. The LV geothermal system exhibits surface manifestations, including over 20 hot springs reaching 47 °C along the lake's southern margin. The upflow zone is represented by the fumarolic field in the Nevado Ojos del Salado volcano, 25 km southwest of LV. Lithium concentrations range from 2.76 to 4.46 mg/L in thermal water and 0.59 to 0.76 mg/L in the Peñas Blancas river water, which feeds into LV after passing through a volcanic environment rich in lithium-bearing rocks. However, the thermal waters contribute over six times more lithium than non-thermal waters, highlighting their significance in releasing and transporting lithium from the source rocks to its eventual accumulation in LV. This natural laboratory at LV provides an excellent opportunity to evaluate the association between geothermal fluids and lithium-rich brines, offering valuable insights into the processes involved in lithium enrichment in similar geological and climatic conditions in other geographic areas.

Metabarcoding reveals unique microbial mat communities and evidence of biogeographic influence in low-oxygen, high-sulfur sinkholes and springs.

High-sulfur, low-oxygen environments formed by underwater sinkholes and springs create unique habitats populated by microbial mat communities. To explore the diversity and biogeography of these mats, samples were collected from three sites in Alpena, Michigan, one site in Monroe, Michigan, and one site in Palm Coast, Florida. Our study investigated previously undescribed eukaryotic diversity in these habitats and further explored their bacterial communities. Mat samples and water parameters were collected from sulfur spring sites during the spring, summer, and fall of 2022. Cyanobacteria and diatoms were cultured from mat subsamples to create a culture-based DNA reference library. Remaining mat samples were used for metabarcoding of the 16S and rbcL regions to explore bacterial and diatom diversity, respectively. Analyses of water chemistry, alpha diversity, and beta diversity articulated a range of high-sulfur, low-oxygen habitats, each with distinct microbial communities. Conductivity, pH, dissolved oxygen, temperature, sulfate, and chloride had significant influences on community composition but did not describe the differences between communities well. Chloride concentration had the strongest correlation with microbial community structure. Mantel tests revealed that biogeography contributed to differences between communities as well. Our results provide novel information on microbial mat composition and present evidence that both local conditions and biogeography influence these unique communities.

Using natural gas content of groundwater to improve the understanding of complex thermo-mineral spring systems

The varied gaseous composition of thermo-mineral waters emerging in a non-active zone reflects the diversity and complexity of groundwater pathways and provides important insights into their hydrogeological behaviours. The investigated geochemical content of complex thermo-mineral springs revealed the need to use dissolved gas contents as part of a multi-tracer approach to discriminate processes, geogenic (water–gas-rock interactions), abiotic (geological confinement, flow paths) and biotic activity influencing geochemical of groundwater along regional pathways. Irrespective of the dissolved element content or the water type, examining the overall concentration of dissolved gases enables an effective delineation of regional groundwater flow paths. Using dissolved gas content further contributed to the circumvention of some analytical challenges associated with conventional isotopic or geochemical techniques, often linked to the high concentration of elements such as iron, sulfate, sulfide or other naturally occurring elements content. The primary objectives are to analyse the gas composition of individual springs, to identify the origin of these gases in the groundwater, and to use this gas composition to improve the understanding of the flow patterns contributing to the geochemical diversity observed at the surface. From field investigations in a geologically and structurally complex area of Eastern Corsica (France), three types of gas contents are identified: (type 1) CH4 & H2S-rich, (type 2) N2-rich and (type 3) CO2-rich. The study of these dissolved gases highlights that the wide geochemical diversity of thermo-mineral waters observed here is not only related to the mineralogical composition of the local aquifer but also involves strong and cumulative interactions along deep regional circulation pathways. This approach also reveals a common deep crustal gaseous influence characterised by N2 production, which interacts during up flow with groundwater and then with the local metamorphic or sedimentary rock matrix. The groundwater’s isotopic and geochemical contents are then altered by local lithologies encountered through both abiotic and biotic interactions. Finally, at shallow depths, phreatic groundwater can add its geochemical and isotopic footprint and dilute this complex mixture before groundwater emerges as mineral spring. This paper answers the primary objectives yet further demonstrates that using dissolved gas as a tracer of groundwater flow paths allows a deeper interpretation of surface geochemical and isotopic observations, distinguishes local from regional flow paths, and provides information about processes at the origin of groundwater diversity.The combination of tools presented in this paper (i.e., geochemical, dissolved gas, and isotopic tools) allows the establishment of a reliable regional groundwater flow scheme for thermo-mineral waters in a non-active zone. This scheme is essential to improve thermo-mineral water management, and protection to ensure their sustainable quality in front of increasing anthropogenic and climatic pressures.

Chemical and 87Sr/86Sr signatures of rainwaters at two active central volcanoes in São Miguel (Azores) – first survey

Rainwater samples were collected during final of February and early March of 2022, at Furnas and Fogo volcanoes, São Miguel (Azores), both of which display secondary manifestations of volcanism. The major-ion composition reveals that marine aerosols contribute significantly to the chemistry of these rainwaters, showed by the proximity of some samples to the Na/Cl ratio of the seawater. The 87Sr/86Sr ratios (0.70849–0.71027) presented by the rainwater samples are similar to the seawater, indicating that marine sprays are possibly the major source of dissolved Sr, with values within the range of values presented by rainwater on the Portuguese mainland. However, other sources, such as volcanic emissions and mineral dust components showed to have also an impact. The 87Sr/86Sr ratios depicted by one sample (CC) deviates from the above mentioned values, exhibiting a lower strontium isotopic ratio (0.70701), which suggests the influence of the fumarolic fluids. Some trace elements (Al, Fe, Mn, Ni, Cu, Zn, Rb, Sr, Ba and REE) content also confirms the influence of the fumarolic emissions, at least in samples collected near Furnas Village fumarolic field (Furnas volcano), and the influence of mineral dust from the surrounding continents (positive anomalies in Eu). Overall, the proximity to an active fumarolic field had a significant impact on the chemistry of meteoric waters, as seen not only in the major-ions, but also in trace elements and in the Sr isotopic ratios.

Mineral springs of Košice basin and their use for balneotourism developement

The article provides insights into the existing state of balneotourism in the Košice Basin area (Eastern Slovakia), emphasizing the insufficient utilization of valuable mineral springs and advocating for immediate efforts in preservation and revitalization. By underscoring the cultural and therapeutic importance of these springs, the paper calls for a renewed dedication to their restoration in the context of modern balneotourism. The study offers a comprehensive examination of the current status of mineral springs in the selected area. Through field research, on-site measurements, and detailed analysis of 23 mineral springs in the Košice Basin's 11 municipalities, the research encompasses various factors, including temperature, chemical composition, yield, drilling depth, overall mineralization, and therapeutic effects. Utilizing a synthesis approach, the research establishes a strategic framework for the effective utilization of mineral waters. These findings play a crucial role in shaping an informed policy aimed at harnessing this valuable resource to drive the development of balneotourism.

Thermal tolerance in an extremophile fish from Mexico is not affected by environmental hypoxia.

The thermal ecology of ectotherm animals has gained considerable attention in the face of human-induced climate change. Particularly in aquatic species, the experimental assessment of critical thermal limits (CTmin and CTmax) may help to predict possible effects of global warming on habitat suitability and ultimately species survival. Here we present data on the thermal limits of two endemic and endangered extremophile fish species, inhabiting a geothermally heated and sulfur-rich spring system in southern Mexico: The sulfur molly (Poecilia sulphuraria) and the widemouth gambusia (Gambusia eurystoma). Besides physiological challenges induced by toxic hydrogen sulfide and related severe hypoxia during the day, water temperatures have been previously reported to exceed those of nearby clearwater streams. We now present temperature data for various locations and years in the sulfur spring complex and conducted laboratory thermal tolerance tests (CTmin and CTmax) both under normoxic and severe hypoxic conditions in both species. Average CTmax limits did not differ between species when dissolved oxygen was present. However, critical temperature (CTmax=43.2°C) in P. sulphuraria did not change when tested under hypoxic conditions, while G. eurystoma on average had a lower CTmax when oxygen was absent. Based on this data we calculated both species' thermal safety margins and used a TDT (thermal death time) model framework to relate our experimental data to observed temperatures in the natural habitat. Our findings suggest that both species live near their thermal limits during the annual dry season and are locally already exposed to temperatures above their critical thermal limits. We discuss these findings in the light of possible physiological adaptions of the sulfur-adapted fish species and the anthropogenic threats for this unique system.

Effects of bathing in different hot spring types on Japanese gut microbiota

Hot springs have been used for a variety of purposes, including the treatment and amelioration of illness and recreation. Japan has ten different types of therapeutic springs (described here as spa types), which are traditionally believed to have different efficacy. However, more research must be conducted to determine how they affect healthy people. Therefore, this study focused on the gut microbiota and aimed to investigate changes in the gut microbiota in healthy people after bathing in different spa types. Using Beppu's hot springs (simple, chloride, bicarbonate, sulfur, and sulfate types), 136 healthy Japanese adults living in the Kyushu area participated in the study and bathed in the same hot spring for seven days. Fecal samples were collected before and after the 7-day bathing period, and the relative abundance of the gut microbiota was determined by 16S rRNA sequencing. The results showed that the relative abundance of Bifidobacterium bifidum increased significantly after seven consecutive days of bathing in the bicarbonate spring. Significant increases in other gut microbiota were also observed after bathing in simple, bicarbonate, and sulfur springs. These results suggest that bathing in different hot springs may affect the gut microbiota in healthy individuals differently.

Contribution to a Sustainable Society: Biosorption of Precious Metals Using the Microalga Galdieria.

The red microalga Galdieria sp. is an extremophile that inhabits acidic hot sulphur springs and grows heterotrophically to a high cell density. These characteristics make Galdieria suitable for commercial applications as stable mass production is the key to success in the algae business. Galdieria has great potential as a precious metal adsorbent to provide a sustainable, efficient and environmentally benign method for urban mining and artisanal small-scale gold mining. The efficiency and selectivity in capturing precious metals, gold and palladium from metal solutions by a Galdieria-derived adsorbent was assessed relative to commercially used adsorbents, ion exchange resin and activated charcoal. As it is only the surface of Galdieria cells that affect metal adsorption, the cell content was analysed to determine the manner of utilisation of those metabolites. Galdieria was shown to be protein-rich and contain beneficial metabolites, the levels of which could shift depending on the growth conditions. Separating the cell content from the adsorbent could improve the adsorption efficiency and reduce CO2 emissions during the metal collection process. The commercial applications of Galdieria appear promising: growth is quick and dense; the precious metal adsorption capacity is highly efficient and selective in acidic conditions, especially at low metal concentrations; and the cell content is nutrient-rich.

Improvement of the knowledge of diatom ecology by coupling geochemistry, radioactivity and taxa inventory in thermo-mineral springs of a volcanic and upland area in south-central France, the Massif Central

ABSTRACT In connection with its geological history, many thermo-mineral springs are present in the Massif Central (France). The physicochemical characteristics of these springs (temperature, mineralization, gas content) result both from their deep circulation and from the geological formations or surface waters with which they interact during their ascent. In mineral springs, diatoms are well represented. To date, no study has focused on coupling the origin of water with diatom communities, whether in the Massif Central or in other parts of the world. The purpose of this study is to cross the information obtained on the water and the diatoms in order to analyse the biodiversity and improve knowledge of the species autecology. Twelve mineral springs with some of which have high levels of radioactivity were studied in the Massif Central. As results, the geochemical facies, the origin of the water and the Total Dissolved Solids influence the taxonomic composition but not the specific richness, Shannon index and Evenness. Furthermore, 222Rn influences diatom richness and community structure. Planothidium frequentissimum, Crenotia angustior and Sellaphora labernardierei were associated with high values of 222Rn activity. The water temperature was a factor that influences diatom species distribution. Some species appears to be more sensitive to the composition of water, such as Planothidium frequentissimum which attests to a mixing between deep and surface waters.

Assessment of Traditional Asphalt Mixture Performance Using Natural Asphalt from Sulfur Springs

This research utilized natural asphalt (NA) deposits from sulfur springs in western Iraq. Laboratory tests were conducted to evaluate the performance of an asphalt mixture incorporating NA and verify its suitability for local pavement applications. To achieve this, a combination of two types of NA, namely soft SNA and hard HNA, was blended to create a binder known as Type HSNA. The resulting HSNA exhibited a penetration grade that adhered to Iraqi specifications. Various percentages of NA (20%, 40%, 60%, and 80%) were added to petroleum asphalt. The findings revealed enhanced physical properties of HSNA, which also satisfied the requirements outlined in the Iraqi specifications for asphalt cement. Consequently, HSNA can serve as an asphalt binder to produce asphalt mixtures for flexible paving construction. Notably, HSNA mixtures exhibited greater Marshall stability and stiffness index when compared to traditional mixtures. The results from indirect tensile strength (ITS) and tensile strength ratio (TSR) tests indicated that the 80NA mixture displayed the highest ITS values and a TSR of 81.36%, surpassing the TSR of the mixture incorporating petroleum asphalt by 0.57%.