Search Results (4)

This study investigates water–rock interactions of Taiwan hot springs by analyzing rare earth elements (REEs) concentrations and strontium (Sr) isotopes. REEs were separated from samples using RE resin, and their concentrations were measured by HR-ICPMS. Strontium was isolated using Sr^SPEC resin, and the strontium isotopic ratio was determined by MC-ICPMS. The ΣREE in the hot springs ranges from 3.17 ng/L to 29.7 µg/L, with the highest levels found in the Tatun Volcano Group, followed by springs from sedimentary and metamorphic regions. The primary factors controlling REE compositions are lithology and pH. REE patterns of hot springs can be categorized into five types, indicating that the hot springs were affected by various mechanisms. The most distinct hot spring samples are from Tatun Volcano, Ginshan, and Kuantzuling. The ⁸⁷Sr/⁸⁶Sr ratios range from 0.70468 to 0.71730, with the most radiogenic samples originating from metamorphic regions, reflecting the nature of the parent rock interacting with the hot spring water. Seawater intrusion and preferential weathering of carbonate also have minor effects on Sr isotope composition. The findings indicate that the types of surrounding rocks and the pH values of the hot springs significantly influence REE patterns and Sr isotope compositions in Taiwan’s hot springs. Full article

The Tatun Volcanic Group (TVG), located in northern Taiwan, is characterized by acidic hot springs where the outflow of the hot springs may affect the properties of the associated lotic water bodies. We investigated the bacterial diversity and functional profiles of the Peihuang (PHC), HuangGang (HGC), and Nanhuang Creeks (NHC) located in the TVG basin using 16S rRNA gene sequencing coupled with statistical analyses. Water samples were collected from various streams of the creeks for two months of the year. The NHC showed the highest diversity, richness, and a unique number of phyla, which was followed by the HGC. A reduced number of phyla and a lower diversity was noticed in the PHC. The NHC was found to be abundant in the genera Armatimonas, Prosthecobacter, Pirellula, and Bdellovibrio, whereas the HGC was rich in Thiomonas, Acidiphilium, Prevotella, Acidocella, Acidithiobacillus, and Metallibacterium. The PHC was abundant in Thiomonsa, Legionella, Acidocella, and Sulfuriferula. The samples did not show any strong seasonal variations with the bacterial diversity and abundance; however, the relative abundance of each sampling site varied within the sampling months. The iron transport protein- and the sulfur metabolism-related pathways were predicted to be the key functions in all the creeks, whereas the heavy metal-related functions, such as the cobalt/nickel transport protein and the cobalt–zinc–cadmium efflux system were found to be abundant in the HGC and PHC, respectively. The abundance of Bdellovibrio in the NHC, Diplorickettsia in the HGC, and Legionella in the PHC samples indicated a higher anthropogenic impact over the creek water quality. This study provides the data to understand the distinct bacterial community structure, as well as the functional potentials of the three major watersheds, and helps the knowledge of the impact of the physicochemical properties of the TVG hot springs upon the watersheds. Full article

The Tatun Volcano Group (TVG) is located in northern Taiwan and consists of many springs and fumaroles. The Tayukeng (TYK) area is the most active fumarole site in the TVG. In this study, we analyzed the long-term geochemical variations of hydrothermal fluids and proposed a mechanism responsible for the variation in TYK. There are two different aquifers beneath the TYK area: a shallow SO₄²⁻-rich aquifer and a deeper aquifer rich in Cl⁻. TYK thermal water was mainly supplied by the shallow SO₄²⁻-rich aquifer; therefore, the thermal water showed high SO₄²⁻ concentrations. After 2015, the inflow of deep thermal water increased, causing the Cl⁻ concentrations of the TYK to increase. Notably, the inferred reservoir temperatures based on quartz geothermometry increased; however, the surface temperature of the spring decreased. We inferred that the enthalpy was lost during transportation to the surface. Therefore, the surface temperature of the spring does not increase with an increased inflow of deep hydrothermal fluid. The results can serve as a reference for understanding the complex evolution of the magma-hydrothermal system in the TVG. Full article

The Tatun geothermal system is located in Northern Taiwan and is hosted by the Tatun volcano group (TVG). The variation in the geochemical composition of thermal waters is considered to be an important indicator of volcanic activity. In this study, we analyzed the chemical and isotopic compositions of hot springs in the TVG. A chemical and multicomponent geothermometer was used to estimate the reservoir temperature, and hydrogen and oxygen isotopes were used to determine the source of the thermal water. The presence of thick andesite and fractures allowed the formation of different type of springs in the center close each other with lower temperatures and acidic springs with higher temperatures at the northeast and southwest sides of the Tatun geothermal field. The saturation index showed that the concentration of SiO₂ in the thermal water was controlled by quartz. The multicomponent geothermometer indicated a reservoir temperature between 130 °C and 190 °C, and the geothermal water in Longfengku, Lengshniken, Matsao and Szehuangping may have mixed with shallow groundwater. Isotope data indicated that the stream water and groundwater originated from meteoric water, and the spring water showed a significant oxygen shift, due to water–rock interaction and evaporation. The isotopes of the fluid in the TVG are also affected by the seasonal monsoon. These results can serve as a reference for designing a conceptual model of the spring in the Tatun geothermal system. Full article