Hot Springs Research Articles

Carboxymethyl chitosan/polyvinyl alcohol hydrogel films by incorporating MSNs as ε-PL carrier with pH-responsive controlled release and antibacterial properties

A hydrogel film with pH-responsive release and excellent antibacterial properties was developed by utilizing mesoporous silica nanoparticles (MSNs) as carriers for ε-PL. Carboxymethyl chitosan (CMCS) is grafted onto aminated-MSNs through amine-bond reaction mediated, which is subsequently bound to polyvinyl alcohol (PVA) by esterification reaction. The addition of MSNs and optimization of CMCS proportion improved the dispersion stability of CMCS/PVA, resulting in a TSI value of 0.6 for 1.6CMCS/0.8PVA@MSNs-ε-PL, which is significantly lower than other groups. The proportion increase of CMCS improved the thermal stability and water oxygen barrier capacities of the 1.6CMCS/0.8PVA@MSNs-ε-PL by enhancing cross-linking with MSNs. The 1.6CMCS/0.8PVA@MSNs-ε-PL exhibited pH-responsive release behavior, with the extent of release increasing proportionally with higher pH levels. The 1.6CMCS/0.8PVA@MSNs-ε-PL exhibited significant antibacterial activity against Pseudomonas azotoformans MN10 in vitro, attributed to the ε-PL's ability to damage the bacterial membrane structure. Hence, the 1.6CMCS/0.8PVA@MSNs-ε-PL exhibits significant potential in food preservation.

Rupture behaviors of the southern Xianshuihe fault and seismicity around Mt. Gongga: Insights from the 2022 MW 6.6 Luding (China) earthquake sequence

The 2022 MW 6.6 Luding earthquake occurred on the Moxi segment of the Xianshuihe fault at the southeast margin of Tibetan Plateau, China. To assess the seismic potential of the Moxi segment, we examine the rupture process of the mainshock and aftershock sequence, along with historical seismicity. Our preferred slip model inverted from teleseismic body waves and regional GNSS static displacements shows a dominant southeastward rupture consisting of two distinct, prominent slip patches along strike extending by ∼15 km, with a peak slip of ∼2.8 m, approximately balancing the slip deficit since the last major earthquake in 1786. The northern section of the Moxi segment experienced minor coseismic slip, which, together with the significant slip deficits and positive Coulomb failure stress change induced by the 2022 mainshock indicates a high seismic potential. Several aftershock clusters are distributed along or near the Moxi segment, with strike-slip focal mechanisms around the downdip edge of the coseismic slip area at ∼8‐12 km. At the eastern flank of Mt. Gongga, another cluster of normal faulting aftershocks is located at shallower depths of ∼3‐7 km, with high seismicity rate over ∼9 months including two other M5 sequences in January and February 2023. Similar intense shallow normal faulting activity had occurred after the impoundment of the nearby Dagangshan reservoir in 2015. We speculate that some NW-SE trending normal faults were initially developed by the gravitational collapse of Mt. Gongga underneath the eastern flank, further weakened by fluid flow, as supported by the existence of hot springs and water impoundment, and reactivated by the tensional stress change induced by the 2022 mainshock. These results have important implications for assessing the seismic hazard in and around the Moxi segment, and the potential interplay between strike-slip fault and nearby mountain areas.

Methylmercury degradation by hot spring sulfur-linked microbial communities as a dominant pathway in regulating mercury speciation

Methylmercury degradation by hot spring sulfur-linked microbial communities as a dominant pathway in regulating mercury speciation

Geochemical (δ13C, δ18O, 87Sr/86Sr, REEs) characterization of travertine in Tengchong, China: Insights into travertine origin and reservoir conditions

Geochemical characterization is extensively employed in travertine research, yet few studies have explored the potential of travertine geochemistry for elucidating the subterranean details of spring systems. In this study, we systematically characterized the geochemical signatures (δ13C, δ18O, 87Sr/86Sr, REEs, Zr, Th, Sr, Mn) of travertine from six spring systems in Tengchong (SW China) and compared them with those of potential reservoir rocks, aiming to understand travertine origin and assess reservoir conditions. Our results revealed substantial variations in the δ13C and δ18O of travertine among the examined systems, but the water temperature and parent CO2 assessments suggest a hot spring thermogene origin of the travertine. The 87Sr/86Sr of the studied travertine also varies significantly among the systems and overlaps with that of potential reservoir rocks. However, only the springs systems with reservoir temperatures exceeding 150 °C are likely to have precipitated travertine with 87Sr/86Sr resembling the whole-rock 87Sr/86Sr of the reservoir rocks. REE contamination by exogenous detritus and FeMn (oxyhydr)oxides was noted, emphasizing the need for careful REE contamination evaluation in travertine research. The REE comparison reveals that the studied travertine does not fully replicate the REE signature of its potential reservoir rocks, but the REE pattern, (Eu/Eu*)SN, and (Ce/Ce*)SN characteristics of the travertine reveal informative reservoir conditions. In summary, this study shows that the geochemistry of the travertine offers valuable insights into its origin and reservoir conditions. These findings could assist in the geochemical interpretation of travertine and the exaction of hypogean reservoir conditions from travertine.

Morphometry and active tectonics of the Konkan coast, western India

The Indian western coast is petroliferous drawing attention from academicians and industrial experts. In this work, geomorphic indices have been calculated to decode neotectonics of the Konkan onshore region on India’s west coast. Earthquake and Bouguer anomaly data have been used along with the present-day stress data from the World Stress Map project. Gravity modeling was performed in order to gain seismotectonic insights. The b-values were determined using Z-MAP 7.1 (2021). Morphometric analysis at both linear and spatial scales were performed using the digital elevation model from the data derived from the Shuttle Radar Topography Mission, analysed with ArcGIS 10.3 (2014) software. Maps depicting slopes, aspects, and reliefs were created. NW-SE trending lineaments in the Konkan plain guided the major stream courses. Two of the five watersheds, watersheds 4 and 5, reveal high tectonic activity, are landslide-prone and host hot springs. Interestingly, watersheds 4 and 5 show high b-values (except near the rivers’ sources), low Bouguer anomalies, and higher Hypsometric integral values (0.18523 and 0.16698) than the other watersheds. A low b-value in watershed 3 indicates stress accumulation. Over a larger area, the gravity trend varies from ∼ -80 to 30 mGal. The lineaments diagram deduced from the first vertical derivative technique shows that the structural fabrics mostly trend ∼ NW-SE at the west of the Western Ghat Escarpment (WGE) while it is NE-SW at the east. The tilt derivative ratio technique reveals a major NE-SW trend to the west of the WGE and an E-W trend to the east. Structural interpretations based on drill-cores around Koyna combined with geophysical studies for deep crust will be required are required for a better understanding of the blind (active) structures in the region.

The metagenomic landscape of a high-altitude geothermal spring in Tajikistan reveals a novel Desulfurococcaceae member, Zestomicrobium tamdykulense gen. nov., sp. nov.

Metagenomic analysis was conducted to assess the microbial community in the high-altitude Tamdykul geothermal spring in Tajikistan. This analysis yielded six high-quality bins from the members of Thermaceae, Aquificaceae, and Halothiobacillaceae, with a 41.2%, 19.7%, and 18.1% share in the total metagenome, respectively. Minor components included Schleiferia thermophila (1.6%) and members of the archaeal taxa Pyrobaculum (1.2%) and Desulfurococcaceae (0.7%). Further analysis of the metagenome-assembled genome (MAG) from the Desulfurococcaceae family (MAG002) revealed novel taxonomy with only 80.95% closest placement average nucleotide identity value to its most closely related member of the Desulfurococcaceae family, which is part of the Thermoproteota phylum comprising hyperthermophilic members widespread in geothermal environments. MAG002 consisted of 1.3 Mbp, distributed into 48 contigs with 1504 predicted coding sequences, had an average GC content of 41.3%, a completeness and contamination rate of 98.7% and 2.6%, respectively, and branched phylogenetically between the Ignisphaera and Zestosphaera lineages. Digital DNA-DNA hybridization values compared with Ignisphaera aggregans and Zestosphaera tikiterensis were 33.7% and 19.4%, respectively, suggesting that this MAG represented a novel species and genus. Its 16S rRNA gene contained a large 421 bp intron. It encodes a complete gluconeogenesis pathway involving a bifunctional fructose-1,6-bisphosphate phosphatase/aldolase; however, the glycolysis pathway is incomplete. The ribulose monophosphate pathway enzymes could be used for pentose synthesis. MAG002 encodes several hydrogen-evolving hydrogenases, with possible roles as hydrogen sinks during fermentation. We propose the name Zestomicrobium tamdykulense gen. nov. sp. nov. for this organism; it is the first thermophilic genome reported from Tajikistan.

Effects of Sulfur Thermal Water inhalations in long-COVID syndrome: spa-centred, double-blinded, randomised case-control pilot study

BackgroundThe long-COVID syndrome is characterised by a plethora of symptoms. Given its social and economic impact, many studies have stressed the urgency of proposing innovative strategies other than hospital settings. In this double-blind randomised case-control trial, we investigate the effects of sulfur thermal water inhalations, rich in H2S, compared to distilled water inhalations on symptoms, inflammatory markers, nasal microbiome in long-COVID patients. Methods30 outpatients aged 18-75, with positive diagnosis for long-COVID were randomised in two groups undergoing 12 consecutive days of inhalations. The active Group (STW) received sulfur thermal water inhalations whereas the placebo group received inhalations of sterile distilled non-pyrogenic water (SDW). Each participant was tested prior treatment at day 1 (T0), after the inhalations at day 14 (T1) and at 3 months follow-up (T2). At each time point, blood tests, nasal swabs for microbiome sampling, pulmonary functionality tests (PFTs) and pro-inflammatory marker measure were performed. ResultsThe scores obtained in the administered tests (6MWT, Borg score, and SGRQ) at T0, showed a significant variation in STW group, at T1 and T2. Serum cytokine levels and other inflammatory biomarkers reported a statistically significant decrease. Some specific parameters of PFT's showed ameliorations in STW group only. Changes in the STW nasopharyngeal microbiota composition were noticed, especially from T0 to T2. ConclusionsInhalations of sulfur thermal water exerted objective and subjective improvements on subjects affected by long-COVID. Significant reduction of inflammatory markers, dyspnea scores and quantitative and qualitative changes in the nasopharyngeal microbiome were also assessed.

Late-stage evolution of hypogene caves at Tyuya-Muyun (Kyrgyzstan): Quantitative insights from mineral deposits

The Tyuya-Muyun massif in SW Kyrgyzstan hosts a number of caves some of which contain Ra- and U-bearing minerals that were extensively mined in the early 20th century. Previous studies have suggested that the caves of the Tyuya-Muyun have experienced a complex speleogenetic history, including epigene and hypogene processes. Here, we reconstruct the late stages of hypogene processes by studying subaqueous (calcite and barite spars, cave clouds), near-water table (rafts, folia) and vadose (flowstone) mineral deposits in Great Barite and Surprise caves. We determined the chronology (230Th dating), stable isotope composition (δ18O, δ13C and Δ47), and formation temperature (fluid inclusion microthermometry and Δ47) of these minerals and reconstructed the oxygen isotopic composition of the paleo-water (δ18Ow). In contrast to previous hypotheses about cave evolution, we found no evidence of an initial epigenic karst phase. The earliest mineral deposits suggest already hydrothermal conditions, with calcite and barite forming at ~40–50 °C prior to 600 ka. Cave clouds in Great Barite Cave mark the beginning of the lowering of the groundwater table and also record a decrease in water temperature from 29.7 ± 8.3 °C to 12.7 ± 5.6 °C, as shown by Δ47 thermometry. The latter temperature remained stable, within analytical uncertainties, during the past 600 ka, as indicated by Δ47 results of near-water table and vadose speleothems in Surprise Cave. At the same time, the decrease in δ18Ow suggests a reduced contribution of thermal water and an increased input of colder meteoric water. By around 540–450 ka Surprise Cave emerged from the phreatic zone, as indicated by 230Th ages of the highest folia and flowstone. This lowering of the water table continued until 84 ka and may have been related to the final uplift phase of the Tyuya-Muyun massif and the concomitant incision of the Aravan River forming the Dangi Gorge.

Unveiling the impact of thermal water in German chamomile infusions: effects on phenolic compounds, antimicrobial and antioxidant properties

German chamomile (GC) and thermal water (TW) are widely known for their biological properties. This study explored whether combining GC with TW could promote an improvement in the bioactivities of GC infusions compared to using drinking water (DW). DW was tested at 100 °C (GC-100DW) and TW at both 100 °C (GC-100TW) and 60 °C (GC-60TW). The use of TW for preparing infusions was associated with the reduction of the number and concentration of extracted phenolic compounds, with GC-60TW showing the lowest levels. It was also associated with a decrease in the antioxidant activity of the samples, as indicated by lower ORAC values and higher EC50 levels for TBARS. However, GC infusions prepared with TW, particularly GC-100TW, exhibited higher antibacterial and antifungal activities. These findings suggest that while TW's high mineral content affected phenolic extraction and antioxidant potential, it was associated with enhanced antimicrobial activity, partially confirming our hypothesis.

Development, characterization and stability of a novel sport drink based on thermal water, apple juice and hibiscus

Isotonic drinks are sports beverages that replenish minerals and rapidly absorbable carbohydrates. We proposed to surpass traditional formulations of isotonic drinks by integrating thermal water, which remains unexploited as a source of electrolytes in isotonic despite the high mineral content. The novel formula combined thermal water with apple juice and hibiscus extract (as sources of sugars and color, respectively, and bioactive compounds). Through comprehensive analysis of chemical, physicochemical, and microbiological properties over 45 days at 4°C and 25°C, the results unveiled an isotonic drink with satisfactory characteristics for this product category: pH of 3.72, 7.93 mg/100 mL of total sugars, and 148.30 mg/100 mL minerals, predominantly sodium (34.99 mg/100 mL) and potassium (73.20 mg/100 mL). It showed significant phenolic compounds, notably chlorogenic acid (2.75±0.10 mg/100 mL), and antioxidant activity (472.72 µmol Trolox eq/100 mL). It maintained a vibrant red hue derived from hibiscus anthocyanins (delphinidin 3-O-sambubioside and cyanidin 3-O-sambubioside, totaling 4.06±0.03 mg/100 mL), and demonstrated microbiological stability throughout the storage period in both temperatures studied. Therefore, by harnessing the potential of thermal water, this study paves the way for a novel approach to developing sports beverages and can serve as a model for countries rich in thermal springs.

Hyperbaric effects on heart rate in professional SCUBA divers in thermal water.

Diving in SCUBA modality modifies human physiology in many ways. These modifications have been studied since Paul Bert in a seminal work. This area of research is very sensible to technological development. At now, it is possible to record heart rate (HR) continuously while diving. The study of HR changes in SCUBA diving at different depths in a constant temperature of thermal water is the objective of the present paper. 18 healthy subjects were enrolled and HR was recorded while SCUBA diving in thermal water at a constant temperature of 33.6∘ C in the deepest Italian pool at Montegrotto (Padova, Italy). Three depths were investigated: -20, -30 and -40 meters. The HR has been recorded with a Galileo SOL diving computer. The dive was subdivided into three phases: descent (DSC), steady on depth (STD), post-dive (RSF), and average HR was evaluated in each phase. Moreover, considering the DSC and STD time duration, a statistical linear regression of HR and relative parameters, intercept and slope, were here assessed. In STD phase, HR slope obtained by regression decreased with depth. A significant difference was found between the slope during STD at -20 vs. -40 m (p ≤ 0.05). Present results emphasized different HR physiological adjustments among diving phases. Firstly, during the DSC, a rapid HR decrease is recognized as probably due to a vagal response; secondly, at STD, the inward blood redistribution requires another physiological adjustment. This latter is depth-dependent because of a reduction of cardiac variability. Present data highlight the important cardiac stress need to counteract the diving activity.

The Source of Thermophilic Bacteria in Lake Baikal Cold Sediments – Coastal Hydrotherms or Deep Fluids?

The sources of thermophilic bacteria revealed in cold Lake Baikal sediments are considered. Comparative analysis of the taxonomic position of thermophilic microorganisms from four terrestrial hot springs at Lake Baikal coast and from the bottom sediments associated with hydrocarbon discharge was carried out. The sequences of thermophilic microorganisms with the same taxonomic position were revealed both in the hot springs and bottom sediments. Some microbial species occurred only in the hydrotherm samples or only in those from the sediments. Gas-saturated fluids from the hydrocarbon generation zone at the depth of 4‒6 km are the most probable source of thermophilic microorganisms in the bottom sediments.

СO2-rich thermal waters of the Neitrino Research Gallery (Baksan Neitrino Observatory, North Caucasus)

Isotope-geochemical (δ2H and δ18O in H2O, δ15N in N2, δ13C in CO2 and CH4,3He/4He) studies of СО2-rich thermal waters (up to 41.3oC) which located in 4 km long tonnel of the Baksan Neutrino Observatory were carried out. The δ13C(CO2) values (–8.0… –6.4‰) indicate the volcanogenic genesis of CO2. The presence of the volcanogenic component is also emphasized by high values of 3He/4He (346 × 10–8). At the same time, nitrogen present in the gas phase is characterized by values of δ15N = +1.3‰, indicating its crustal genesis. In the tunnel, an elevated concentration of CH4 (up to 0.5%) was noted in one of the gas outlets. This methane is characterized by high δ13C values (–33.5 and –26.0‰), which, in general, are typical for other СО2-rich springs of the Eastern Elbrus Mountains. In contrast with the other CO2-rich springs of the North Caucasus, which are practically indistinguishable from surface waters in terms of δ2H and δ18O values, the CO2-rich thermal springs of the tunnel are noticeably enriched in heavy oxygen isotope (18O). This is a consequence of oxygen exchange between the waters and the host rocks at elevated temperatures. In the δ18O-δ2H diagram, the figurative points of thermal waters form a trend that reflects the mixing of isotope-light infiltration waters with isotope-heavy waters.

Preparation and characterization of novel natural pigment-indicating film: Application in kiwifruit freshness monitoring

The marketability of natural pigment-based indicator films is impeded by their weaker color rendering and stability compared with synthetic pigments. Here, we developed novel colorimetric indicators by blending polyvinyl alcohol (PVA) with carboxymethyl cellulose (CMC) and combining alizarin and curcumin. Compared with the individual materials, the PVA and CMC composite films demonstrated superior thermal stability and water resistance. The manufacturing process of these colorimetric indicators was optimized using response surface methodology. The optimum conditions were as follows: PVA at 3.92 g/100 mL; plate pour amount, 48.6 mL; pigment content, 5.8 g/100 mL; pigment ratio, 0.76. The optimized film showed a robust response to CO2 (a color difference of 65.06 ± 2.43). The color difference of the optimized film improved by 98.5 % and 16.86 % for kiwifruit stored at room and low temperatures, respectively. This substantial color change aids in identifying the optimal consumption window for kiwifruit, boosting indicator precision and kiwifruit freshness accuracy.

Effect of 8-Week Hot Spring Exercise on Lumbar Isokinetic Function and Oswestry Disability Index in Middle-aged Women with Low Back Pain

Effect of 8-Week Hot Spring Exercise on Lumbar Isokinetic Function and Oswestry Disability Index in Middle-aged Women with Low Back Pain

Effect of an 8-week hot spring water exercise program on body composition, knee isokinetic muscle function, range of motion, and the Korean Western Ontario and Mcmaster Universities index in middle-age females with osteoarthritis in Republic of Korea: experiment study

Effect of an 8-week hot spring water exercise program on body composition, knee isokinetic muscle function, range of motion, and the Korean Western Ontario and Mcmaster Universities index in middle-age females with osteoarthritis in Republic of Korea: experiment study

The Effects of Age-Specific Hot Spring Trekking Health Tours on Brain Waves and Heart Rate Variability

The Effects of Age-Specific Hot Spring Trekking Health Tours on Brain Waves and Heart Rate Variability

Development of Poly(lactic acid)-Based Biocomposites with Silver Nanoparticles and Investigation of Their Characteristics

Nowadays, the demand for food packaging that maintains the safety and quality of products has become one of the leading challenges. It can be solved by developing functional materials based on biodegradable polymers, such as poly(lactic acid) (PLA). In order to develop PLA-based functional materials with antibacterial activity, silver nanoparticles (AgNPs) were introduced. In the present study, AgNPs stabilized by a copolymer of ethylene and maleic acid were used. Under the joint action of shear deformations and high temperature, the biocomposites of PLA with poly(ethylene glycol) and AgNPs were produced. Their mechanical and thermal characteristics, water absorption, and structure were investigated using modern methods (DSC, FTIR, Raman spectroscopy, SEM). The effect of AgNP concentration on the characteristics of PLA-based biocomposites was detected. Based on the results of antibacterial activity tests (against Gram-positive and Gram-negative bacteria, along with yeast) it is assumed that these systems have potential as materials for extending the storage of food products. At the same time, PLA–PEG biocomposites with AgNPs possess biodegradability.

Investigation and Validation of Split-Window Algorithms for Estimating Land Surface Temperature from Landsat 9 TIRS-2 Data

Land surface temperature (LST) is important in a variety of applications, such as urban thermal environment monitoring and water resource management. In this paper, eleven candidate split-window (SW) algorithms were adapted to Thermal Infrared Sensor-2 (TIRS-2) data of the Landsat 9 satellite for estimating the LST. The simulated dataset produced by extensive radiative transfer modeling and five global atmospheric profile databases was used to determine the SW algorithm coefficients. Ground measurements gathered at Surface Radiation Budget Network sites were used to confirm the efficiency of the SW algorithms after their performance was initially examined using the independent simulation dataset. Five atmospheric profile databases perform similarly in training accuracy under various subranges of total water vapor. The candidate SW algorithms demonstrate superior performance compared to the radiative transfer equation algorithm, exhibiting a reduction in overall bias and RMSE by 1.30 K and 1.0 K, respectively. It is expected to provide guidance for the generation of the Landsat 9 LST using the SW algorithms.

Flat plate solar collector activated with alumina-silicon dioxide-copper oxide hybrid nanofluid: Thermal performance study

Flat plate collectors (FPC) play a crucial role in solar-powered desalination by harnessing sunlight to purify water. They are acclaimed for their simple yet efficient design, as their dark, flat surfaces effectively transfer heat to the desalination system, making them a preferred choice for sustainable water treatment. Nevertheless, the performance of FPC systems is hindered by the working fluid, which reduces the productivity of distilled water, particularly without the use of nanotechnology to enhance the fluid’s thermal properties. This study aims to enhance the performance of FPCs in desalination processes by integrating them with conventional still systems and employing hybrid nanofluids. These nanofluids, composed of alumina (Al2O3), silicon dioxide (SiO2), and copper oxide (CuO) nanoparticles at concentrations of 0.3 % in 50:50 combinations, namely Al2O3/SiO2, SiO2/CuO, and Al2O3/CuO, are introduced into the working fluid (water). The integration of these hybrid nanofluids is evaluated in terms of thermal behaviour, including thermal conductivity, outlet temperature, energy gain, water productivity, and thermal and exergy efficiency of FPC. Among the different combinations, the Al2O3/CuO hybrid nanofluid demonstrates the highest thermal conductivity, outlet temperature, energy gain, water productivity, as well as thermal and exergy efficiencies, reaching approximately 0.631 W/mK, 87.5 °C, 568.7 W, 124.3 ml/m2, 61.4 %, and 6.7 %, respectively. The Al2O3/CuO featured flat plate solar collector system has the potential for an optimum system of addressing the pressing global issue of water scarcity.