Dissolved Gases

This study presents a predictive modeling approach for monitoring moisture and dissolved oxygen dynamics in a newly commissioned high-capacity power transformer. Using over 48,000 real-time observations collected across three years via an advanced online monitoring device installed on a 326 MVA generator step-up transformer (GSUT), machine learning models were developed to estimate moisture and oxygen concentrations based on correlated operational parameters. Multiple regression-based algorithms were trained and evaluated using performance metrics including root mean squared error (RMSE), mean absolute error (MAE), and coefficient of determination (R²). Linear regression achieved superior performance with an RMSE values as low as 0.05888 ppm for oxygen and 0.0153 ppm for moisture. The models were further validated using data from a sister transformer, demonstrating generalizability and reliability across similar transformer units. This work contributes a scalable and accurate solution for real-time transformer health assessment, with practical implications for predictive maintenance strategies in power utilities.

Diese Arbeit untersucht den Einfluss gelöster Gase auf das Viskositäts-Druck-Verhalten flüssiger Kohlenwasserstoffe unter hohen Drücken. Die Arbeit adressiert insbesondere die Phänomene, die in gesättigten und untersättigten Gas-Flüssigkeitslösungen auftreten, und ihre Relevanz für technische Anwendungen wie die Erdölförderung und die chemische Verfahrenstechnik. Um die Viskositätsveränderungen präzise zu messen, wurde eine Hochdruckapparatur entwickelt, die mit einem speziell angefertigten Federbalg-Kapillarviskosimeter ausgestattet ist.
In den Experimenten wurden Methan, Ethan, Propan und Kohlenstoffdioxid in verschiedenen Flüssigkeiten wie Squalan und Paraffinöl gelöst. Die Studie zeigt, dass sich die Viskosität der Lösungen signifikant verändert, abhängig von Druck, Temperatur und der Art des gelösten Gases. Die Messergebnisse wurden sowohl graphisch als auch analytisch ausgewertet, und es wurden empirische Formeln entwickelt, um diese Phänomene vorherzusagen.
Die Ergebnisse leisten einen wichtigen Beitrag zur besseren Vorhersage der Viskosität in industriellen Prozessen und erweitern das Verständnis des Phasenverhaltens von Gas-Flüssigkeits-Gemischen.

This work investigates the influence of dissolved gases on the viscosity-pressure behavior of liquid hydrocarbons under high pressures. The study focuses on phenomena occurring in saturated and undersaturated gas-liquid solutions and their relevance for technical applications such as oil extraction and chemical process engineering. A high-pressure apparatus equipped with a specially designed bellows-capillary viscometer was developed to precisely measure viscosity changes.
The experiments involved dissolving methane, ethane, propane, and carbon dioxide in various liquids, including squalane and paraffin oil. The study demonstrates significant changes in solution viscosity, depending on pressure, temperature, and the type of dissolved gas. The measurement results were analyzed both graphically and analytically, leading to the development of empirical equations to predict these phenomena.
The findings contribute to improving the prediction of viscosity in industrial processes and enhance the understanding of the phase behavior of gas-liquid mixtures.

This bibliographic report analyzes the equilibrium of dissolved gases in water and their interaction with the atmosphere, focusing on atmospheric composition and chemical equilibrium according to Henry’s Law. The role of CO₂ in acid-base equilibrium is examined, highlighting the natural acidity of rainwater and the effect of SO₂, relating it to the phenomenon of acid rain. Biogeochemical cycles and the interaction among the five environmental spheres are also discussed, emphasizing the exchange of matter and energy between them. Furthermore, the report addresses mass balances and fluxes in equilibrium systems, including simple, multiple, and out-of-equilibrium systems. Understanding these concepts is essential for environmental management and assessing anthropogenic impacts on natural cycles (Manahan, 2007). Proper management of these systems helps mitigate adverse effects, promoting sustainable ecosystem development.

The objective of the study was to evaluate the different headspace equilibration methods for the quantification of dissolved greenhouse gases in groundwater. Groundwater samples were collected from wells with contrasting hydrogeochemical properties and degassed using the headspace equilibration method. One hundred samples from each well were randomly selected, treatments were applied and headspace gases analysed by gas chromatography. Headspace equilibration treatments varied helium (He): water ratio, shaking time and standing time. Mean groundwater N 2 O, CO 2 and CH 4 concentrations were 0.024 mg N L-1 , 13.71 mg C L-1 and 1.63 μg C L-1 , respectively. All treatments were found to significantly influence dissolved gas concentrations. Considerable differences in the optimal He: water ratio and standing time were observed between the three gases. For N 2 O, CO 2 and CH 4 the optimum operating points for He: water ratio was 4.4:1, 3:1 and 3.4:1; shaking time was 13, 12 and 13 min; and standing time was 63, 17 and 108 min, respectively. The headspace equilibration method needs to be harmonised to ensure comparability between studies. The experiment reveals that He: water ratio 3:1 and shaking time 13 min give better estimation of dissolved gases than any lower or higher ratios and shaking times. The standing time 63, 17 and 108 min should be applied for N 2 O, CO 2 and CH 4 , respectively.

Davis (UCD), the San Joaquin River Group Authority (SJRGA) and SJVDA are cooperating participants on Task 4. This report and associated electronic files represent the major annual deliverable for Task 4. Chapters 2, 3, and 8 and Appendixes D were written primarily to document programmatic progress under the Task 4 research effort. Chapter 2 describes the methods used for data collection and the results of the Task 4 quality assurance program. Chapter 3 and Appendix D describes and documents field research activities undertaken by the Environmental Engineering Research Program (EERP) at the University of the Pacific. Chapter 8 documents activities associated with the collection of continuous chlorophyll concentration data at critical locations on the SJR. Chapters 1, 2, 4, and 5 and Appendixes A, B, C, E, F, and G were written to assist in the transfer of electronic data from the DO TMDL Program to cooperators on the project and to provide a summary analysis of the data for reference. These chapters and Appendixes also serve to document the extensive programmatic effort associated with Task 4. Chapters 4, 5, 6, and 7 provide scientific analysis of the Task 4 data independently of the Task 6 Modeling effort. Other scientific analysis are in progress and will be included in subsequent reports. The Project plan is to collect three years of data (2005, 2006, and 2007) and to present a final scientific analysis in 2008. This report is a interim deliverable on the project and scientific analysis presented here is considered preliminary in nature.

Seismic-volcanic unrest was detected between 2004 and 2005 in the central and northwest zones of Tenerife Island (Canary Islands, Spain). With the aim of strengthening the program of geochemical and seismicvolcanic surveillance, a study of the origin, characteristics, and spatial distribution of dissolved carbon dioxide (CO 2) and helium (He) gases in the volcanic aquifer of central Tenerife Island and around Teide volcano was carried out. This work also improves the hydrogeological and hydrogeochemical conceptual model of groundwater flow. Dissolved CO 2 concentrations in sampled groundwater are several orders of magnitude higher than that of air-saturated water (ASW) suggesting a significant contribution of nonatmospheric CO 2 , mainly magmatic, confirmed through measurement of isotopic compositions (δ 13 C TDIC) and total dissolved inorganic carbon (TDIC) concentrations. A vertical stratification of dissolved CO 2 and δ 13 C TDIC values was observed in the volcanic aquifer at the eastern region of Las Cañadas Caldera. Stratification seems to be controlled by both degree of magmatic CO 2-water interaction and CO 2 degassing and the original δ 13 Cco 2(g) isotopic composition. The highest dissolved helium (4 He) concentrations in groundwater seem to be related to radiogenic contributions resulting from waterrock interactions, and increase with residence time, instead of with endogenous magmatic inputs. Isotopic systematics show that the dissolved gases in groundwater of central Tenerife are variable mixtures of CO 2-3 He-rich fluids of volcanic-hydrothermal origin with both organic and atmospheric components. The results suggest that the eastern area of Las Cañadas Caldera, the South Volcanic Ridge, and the Teide summit cone are the areas most affected by degassing of the volcanic-hydrothermal system, and they are therefore the most suitable zones for future geochemical monitoring.

Unexpected gas accumulation in a safety system of nuclear power plants can damage system elements and degrade cooling performance. To prevent the gas accumulation, it is important to define the mechanism of gas accumulation occurred by separation of dissolved gas. In the current research, it is investigated how the variations of temperature and pressure affect separation of dissolved gases and accumulation of non-condensable gases. The experimental study is conducted on three subjects; gas accumulations by variations of (1) pressure, (2) temperature and (3) order of temperature and pressure changes. Before performing each experiment, demineralized water is stabilized under the initial condition (20°C and atmospheric pressure) for more than 24 h. In a closed system, the gas accumulation cannot be occurred by pressure change. By heating water, the gas accumulation is generated. When the water is kept in higher temperature, the more gases are accumulated. Even if the water is cooled back to the initial condition, the accumulated gas is remained more than 50%. By changing the order of temperature and pressure variations, the gas is accumulated. In results, it is found that the gas accumulation can be generated if the solubility of dissolved gas becomes lower than initial condition. Additionally, it is found that the gas already accumulated in the system is difficult to remove without additional venting process.

Seismic-volcanic unrest was detected between 2004 and 2005 in the central and northwest zones of Tenerife Island (Canary Islands, Spain). With the aim of strengthening the program of geochemical and seismicvolcanic surveillance, a study of the origin, characteristics, and spatial distribution of dissolved carbon dioxide (CO 2) and helium (He) gases in the volcanic aquifer of central Tenerife Island and around Teide volcano was carried out. This work also improves the hydrogeological and hydrogeochemical conceptual model of groundwater flow. Dissolved CO 2 concentrations in sampled groundwater are several orders of magnitude higher than that of air-saturated water (ASW) suggesting a significant contribution of nonatmospheric CO 2 , mainly magmatic, confirmed through measurement of isotopic compositions (δ 13 C TDIC) and total dissolved inorganic carbon (TDIC) concentrations. A vertical stratification of dissolved CO 2 and δ 13 C TDIC values was observed in the volcanic aquifer at the eastern region of Las Cañadas Caldera. Stratification seems to be controlled by both degree of magmatic CO 2-water interaction and CO 2 degassing and the original δ 13 Cco 2(g) isotopic composition. The highest dissolved helium (4 He) concentrations in groundwater seem to be related to radiogenic contributions resulting from waterrock interactions, and increase with residence time, instead of with endogenous magmatic inputs. Isotopic systematics show that the dissolved gases in groundwater of central Tenerife are variable mixtures of CO 2-3 He-rich fluids of volcanic-hydrothermal origin with both organic and atmospheric components. The results suggest that the eastern area of Las Cañadas Caldera, the South Volcanic Ridge, and the Teide summit cone are the areas most affected by degassing of the volcanic-hydrothermal system, and they are therefore the most suitable zones for future geochemical monitoring.

A new method for extracting dissolved gases in natural waters has been developed and tested, both in the laboratory and in the field. The sampling device consists of a polytetrafluroethylene (PTFE) tube (waterproof and gas permeable) sealed at one end and connected to a glass sample holder at the other end. The device is pre-evacuated and subsequently dipped in water, where the dissolved gases permeate through the PTFE tube until the pressure inside the system reaches equilibrium. A theoretical model describing the time variation in partial gas pressure inside a sampling device has been elaborated, combining the mass balance and ''Solution-Diffusion Model'' (which describes the gas permeation process through a PTFE membrane). This theoretical model was used to predict the temporal evolution of the partial pressure of each gas species in the sampling device. The model was validated by numerous laboratory tests. The method was applied to the groundwater of Vulcano Island (southern Italy). The results suggest that the new sampling device could easily extract the dissolved gases from water in order to determine their chemical and isotopic composition.

Prokaryotic diversity in lakes has been studied for many years mainly focusing on community structure and how the bacterial assemblages are driven by physicochemical conditions such as temperature, oxygen, and nutrients. However, little is known about how the composition and function of the prokaryotic community changes upon lake stratification. To elucidate this, we studied Lake Cote in Costa Rica determining prokaryotic diversity and community structure in conjunction with physicochemistry along vertical gradients during stratification and mixing periods. Of the parameters measured, ammonium, oxygen, and temperature, in that order, were the main determinants driving the variability in the prokaryotic community structure of the lake. Distinct stratification of Lake Cote occurred (March 2018) and the community diversity was compared to a period of complete mixing (March 2019). The microbial community analysis indicated that stratification significantly altered the bacterial composit...

Seismic-volcanic unrest was detected between 2004 and 2005 in the central and northwest zones of Tenerife Island (Canary Islands, Spain). With the aim of strengthening the program of geochemical and seismicvolcanic surveillance, a study of the origin, characteristics, and spatial distribution of dissolved carbon dioxide (CO 2) and helium (He) gases in the volcanic aquifer of central Tenerife Island and around Teide volcano was carried out. This work also improves the hydrogeological and hydrogeochemical conceptual model of groundwater flow. Dissolved CO 2 concentrations in sampled groundwater are several orders of magnitude higher than that of air-saturated water (ASW) suggesting a significant contribution of nonatmospheric CO 2 , mainly magmatic, confirmed through measurement of isotopic compositions (δ 13 C TDIC) and total dissolved inorganic carbon (TDIC) concentrations. A vertical stratification of dissolved CO 2 and δ 13 C TDIC values was observed in the volcanic aquifer at the eastern region of Las Cañadas Caldera. Stratification seems to be controlled by both degree of magmatic CO 2-water interaction and CO 2 degassing and the original δ 13 Cco 2(g) isotopic composition. The highest dissolved helium (4 He) concentrations in groundwater seem to be related to radiogenic contributions resulting from waterrock interactions, and increase with residence time, instead of with endogenous magmatic inputs. Isotopic systematics show that the dissolved gases in groundwater of central Tenerife are variable mixtures of CO 2-3 He-rich fluids of volcanic-hydrothermal origin with both organic and atmospheric components. The results suggest that the eastern area of Las Cañadas Caldera, the South Volcanic Ridge, and the Teide summit cone are the areas most affected by degassing of the volcanic-hydrothermal system, and they are therefore the most suitable zones for future geochemical monitoring.

Seismic-volcanic unrest was detected between 2004 and 2005 in the central and northwest zones of Tenerife Island (Canary Islands, Spain). With the aim of strengthening the program of geochemical and seismicvolcanic surveillance, a study of the origin, characteristics, and spatial distribution of dissolved carbon dioxide (CO 2) and helium (He) gases in the volcanic aquifer of central Tenerife Island and around Teide volcano was carried out. This work also improves the hydrogeological and hydrogeochemical conceptual model of groundwater flow. Dissolved CO 2 concentrations in sampled groundwater are several orders of magnitude higher than that of air-saturated water (ASW) suggesting a significant contribution of nonatmospheric CO 2 , mainly magmatic, confirmed through measurement of isotopic compositions (δ 13 C TDIC) and total dissolved inorganic carbon (TDIC) concentrations. A vertical stratification of dissolved CO 2 and δ 13 C TDIC values was observed in the volcanic aquifer at the eastern region of Las Cañadas Caldera. Stratification seems to be controlled by both degree of magmatic CO 2-water interaction and CO 2 degassing and the original δ 13 Cco 2(g) isotopic composition. The highest dissolved helium (4 He) concentrations in groundwater seem to be related to radiogenic contributions resulting from waterrock interactions, and increase with residence time, instead of with endogenous magmatic inputs. Isotopic systematics show that the dissolved gases in groundwater of central Tenerife are variable mixtures of CO 2-3 He-rich fluids of volcanic-hydrothermal origin with both organic and atmospheric components. The results suggest that the eastern area of Las Cañadas Caldera, the South Volcanic Ridge, and the Teide summit cone are the areas most affected by degassing of the volcanic-hydrothermal system, and they are therefore the most suitable zones for future geochemical monitoring.

Volcanic lakes are characterized by physicochemical favorable conditions for the development of reservoirs of C-bearing greenhouse gases that can be dispersed to air during occasional rollover events. By combining a microbiological and geochemical approach, we showed that the chemistry of the CO2- and CH4-rich gas reservoir hosted within the meromictic Lake Averno (Campi Flegrei, southern Italy) are related to the microbial niche differentiation along the vertical water column. The simultaneous occurrence of diverse functional groups of microbes operating under different conditions suggests that these habitats harbor complex microbial consortia that impact on the production and consumption of greenhouse gases. In the epilimnion, the activity of aerobic methanotrophic bacteria and photosynthetic biota, together with CO2 dissolution at relatively high pH, enhanced CO2- and CH4 consumption, which also occurred in the hypolimnion. Moreover, results from computations carried out to evalu...

Here, we present a metagenomic analysis of the microflora of the surface waters of the Shardara reservoir, the largest artificial reservoir in Southern Kazakhstan, created to meet irrigation and hydropower engineering needs. In this case, shotgun metagenomic sequencing of the microbial community DNA was used.

Volcanic lakes are characterized by physicochemical favorable conditions for the development of reservoirs of C-bearing greenhouse gases that can be dispersed to air during occasional rollover events. By combining a microbiological and geochemical approach, we showed that the chemistry of the CO2- and CH4-rich gas reservoir hosted within the meromictic Lake Averno (Campi Flegrei, southern Italy) are related to the microbial niche differentiation along the vertical water column. The simultaneous occurrence of diverse functional groups of microbes operating under different conditions suggests that these habitats harbor complex microbial consortia that impact on the production and consumption of greenhouse gases. In the epilimnion, the activity of aerobic methanotrophic bacteria and photosynthetic biota, together with CO2 dissolution at relatively high pH, enhanced CO2- and CH4 consumption, which also occurred in the hypolimnion. Moreover, results from computations carried out to evaluate the dependence of the lake stability on the CO2/CH4 ratios, suggested that the water density vertical gradient was mainly controlled by salinity and temperature, whereas the effect of dissolved gases was minor, excepting if extremely high increases of CH4 are admitted. Therefore, biological processes, controlling the composition of CO2 and CH4, contributed to stabilize the lake stratification of the lake. Overall, Lake Averno, and supposedly the numerous worldwide distributed volcanic lakes having similar features (namely bio-activity lakes), acts as a sink for the CO2 supplied from the hydrothermal/magmatic system, displaying a significant influence on the local carbon budget.

Water is the most essential commodity for the sustenance of life. Water is a chemical substance with the formula H2O.It is found in 3 states liquid, solid and gases. 97% earth surface covered by water. Animals & plants have 60-65 % water in their body. The availability of water on earth are immense in which mostly sea water which is unfit for drinking or irrigation purpose. The amount of fresh water is huge as well, but its distribution over the globe is uneven. The demands for drinking, other domestic needs are increases from 135 to 500 liters a day per person. Water plays an important role in making human life for survive. As man uses water he pollutes it and when the waste water is returned to open bodies it contaminates the natural waters. So, the quality of water and waste water plays an important role for experts in all over the world. Water keeps on cycling endlessly through environment " Hydrological cycle ". The paper includes the Chemical quality parameter examined in water and waste waters.