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Seaver, G.A. and Kuzirian, A.M., 2024. Estuary nitrate sources and trends in Buzzards Bay. Journal of Coastal Research, 40(6), 1055–1067. Charlotte (North Carolina), ISSN 0749-0208. The determination of estuary nitrate sources originating through groundwater was the principal objective of this work. This required long timeline (35-year) measurements over many seasonal cycles. Typically, in this study, nitrate sources were an upgradient from estuaries at a significant distance, usually greater than 300 m (1000 ft), whereas groundwater flow that transported the nitrate near the coast in Buzzards Bay, Massachusetts, traveled only 0.45 m/d (1.5 ft/d). Thus, it takes years before a potential newly discovered nitrate source could be confirmed in the estuary. Investigation of estuary nitrate trends and the significance of obtaining winter nitrate measurements to investigations was more fully developed in this work. This showed that determining the estuarian nitrate trends also required a timeline much longer than the variability of the nitrate influx into the estuary. The large, summer-to-winter high nitrate (but not low nitrate) differences and the system's inherent physiological ecology were central to regulating nitrate in an estuary, despite greatly increased groundwater nitrate input. The winter measurement data explained this phenomenon. Finally, the data measurement program completed in Buzzards Bay proved to be ideal in answering these necessarily long timeline questions. The research suggested a new parameter be used to indicate an excess nitrate state of an estuary. These long-term data also allowed meaningful calculations of estuarine and groundwater nitrate and temperature trends. [ABSTRACT FROM AUTHOR]

Intertidal groundwater springs provide thermally stable, nutrient‐rich freshwater that causes fine‐scale variability in water temperature and salinity and promotes biodiversity in coastal estuaries and lagoons. In this study, we combined three thermal sensing techniques to elucidate summer water temperature patterns at the mouths of intertidal groundwater springs and the ambient coastal lagoon in Prince Edward Island, Canada. Thermal infrared imagery captured the spatiotemporal variability in relative temperatures of the lagoon channel and cold‐water plumes from the springs. Thermal anomalies due to the springs were detected at the surface throughout a tidal cycle, suggesting that the thermal plumes were buoyant. Fiber‐optic distributed temperature sensing paired with temperature loggers near the spring outlets recorded groundwater temperatures at low tide (~ 7°C) but ambient lagoon temperatures (up to 26°C) at high tide due to the vertical thermal gradient in the stratified water column. Calculated estuarine Richardson numbers throughout the study confirm intertidal spring buoyancy due to salinity differences. The fiber‐optic distributed temperature sensing results revealed pronounced variations in temperature as evidenced by spatial (3.7°C) and temporal (5.5°C) standard deviations over the cable length during the study and lower mean lagoon bed water temperatures at high tide (22.5°C) than low tide (24.3°C) due to heat advection from tidal pumping. Lagoon temperatures fluctuate at diurnal (solar) and semi‐diurnal (tidal) frequencies. The findings emphasize the efficacy of a multi‐technology approach to reveal fine‐scale and dynamic thermal processes that drive temperature patterns and habitat distribution in coastal lagoon ecosystems and highlight the thermal influence of intertidal springs. [ABSTRACT FROM AUTHOR]

This study was conducted to investigate the presence of benzene in the ground and drinking water in the eastern Niger Delta, where multiple oil and gas production facilities are present. Samples from drinking water wells were collected for measurements of benzene, toluene, ethylbenzene, and xylenes (BTEX). Additionally, the dissolved organic carbon (DOC) concentration was determined for the first time to establish the groundwater's total hydrocarbon and non-hydrocarbon load. The groundwater BTEX and benzene levels were up to 3904 µg/L and 3500 µg/L, respectively. DOC concentrations were up to 49 mg/L. The highest benzene concentrations were detected in wells near an underground petroleum pipeline. However, the concentrations decreased with distance from the pipeline to levels less than 0.1 µg/L. Despite benzene contamination, the aquifer has shown promising aerobic attenuation potential, having up to a 7.5 (95%) mg/L DO level and 2.11 mg/L BTEX biodegradation capacity for DO. However, the high groundwater temperature of up to 32.5 °C may weaken attenuation. The benzene and BTEX point attenuation rates ranged from 0.128 to 0.693 day−1 and 0.086 to 0.556 day−1, respectively. Hence, by natural attenuation alone, up to 66.5 and 85 years would be required to reach Nigeria's groundwater benzene and BTEX remediation goals, respectively. [ABSTRACT FROM AUTHOR]

This study utilized a pilot-scale distribution network to examine the impact of temperature increases (16 °C, 20 °C, 24 °C) and source variations (treated ground- and surface water) on bulk and biofilm communities over 137 days. Microbial characterization employed flow cytometry and 16 S rRNA gene-based amplicon sequencing to elucidate bulk-biofilm interactions. Bacterial bulk cell densities increased with higher temperatures, while water source variations significantly influenced bulk cell densities as well as the community composition. Additionally, growth curves were fitted on the flow cytometry results, and growth rates and carrying capacities were higher with treated groundwater at elevated temperatures. Conversely, biofilm cell densities remained unaffected by temperature. A mature biofilm was observed from day 70 onwards and a core biofilm microbiome, resilient to temperature and water source changes, was identified. These findings emphasize the importance of water source quality for maintaining biological stability in drinking water systems, particularly in the face of changing environmental conditions. [ABSTRACT FROM AUTHOR]

São Vicente Medical Spa is located in mainland Portugal (Southwest Europe) and has been using thermal waters for therapeutic purposes for a long time. The Romans were known to have used its sulphureous waters around 2000 years ago. The spa has a Roman bathhouse that is still visible today, and its ruins were discovered during recent excavations. In this work are presented some elements of the Roman baths, the current baths, as well as the main aspects of the thermal park, with the location of the sulphureous water abstractions, including the classic thermal spring, which discharges water at a temperature of 18.6 ºC. The geomorphological, geological, and hydrogeological aspects are outlined, giving particular attention to the water chemistry of the various abstractions to develop multiple applications of geothermometers to contribute to the knowledge of the geohydraulic model at depth and the geothermal potential of the aquifer system. The conclusions are drawn from a conceptual model, including the reservoir depth, which, according to various scenarios, will be between 3 km and 8 km, in a favorable situation, respectively, to reach groundwater with temperatures between 112 ºC and 118 ºC. Finally, some remarks are made about the location of the new groundwater abstraction and the depth to be reached to increase the exploitation flows and their temperature. Lastly, it outlined new studies to improve the current geohydraulic model and to investigate its relationship with the deep aquifer systems in its neighborhood, namely the Entre-os-Rios hydromineral system. [ABSTRACT FROM AUTHOR]

In order to gain a deeper understanding of the effects of environmental factors on the formation of Populus euphratica xylem, this study analysed the anatomical characteristics of Populus euphratica xylem and its response to environmental factors using wood anatomy as an example of Populus euphratica in the Yingsu section of the lower Tarim River. The results showed the following: (1) Throughout the growing season, the number of conduits of Populus euphratica in the two sample sites showed a slow increasing trend with the increase in groundwater burial depth, and the total conduit area showed an increasing and then decreasing trend with the increase in groundwater burial depth. The four indices of total, minimum, average, and maximum conduit areas in Populus euphratica xylem increased significantly with increasing temperatures during the growing season. (2) From the principal component analysis, the anatomical parameters of Populus euphratica xylem were found to be positively correlated with the depth of groundwater, average air temperature, maximum air temperature, minimum air temperature, surface temperature, relative humidity, and saturated water and air pressure deficit in the two sampling sites The most significant effects were found in the air temperature and depth of the groundwater. (3) The contribution of groundwater level and air temperature to different growth stages of Populus euphratica xylem was different. During the early part of the growing season of Populus euphratica, the air temperature was the main factor influencing the number of xylem conduits and total conduit area. As the growing season entered the middle stage, the air temperature and groundwater together affected the conduit parameters. In the later part of the growing season, groundwater became the most important factor affecting the number of conduits and the total conduit area. (4) The sensitivity analyses yielded a sensitive groundwater burial depth of 5.2 m for changes in the number of conduits in the xylem of the Populus euphratica and 5.9 m for changes in the total conduit area; the sensitive air temperature for the total conduit area in the xylem of the Populus euphratica was 22.0 °C, and the sensitive air temperature for the average conduit area was 18.5 °C. The results of this study can have important theoretical significance for understanding the Populus euphratica forests, as well as ecological water resource management in the lower Tarim River. They also provide scientific basis for the restoration and protection of Populus euphratica forests in the lower Tarim River. [ABSTRACT FROM AUTHOR]

The thermal conditions of transitional (ranging from warm to cold) coldwater streams impact the ranges and resource availabilities for biota inhabiting these lotic systems. With ongoing climate change and increasing land modifications, thermal boundaries may shift, altering thermal transition zones and their biotic communities. The objective of this study was to investigate the condition of trout across three forks of the Whitewater River catchment, located in southeastern Minnesota, and to investigate factors influencing fish community composition and distribution. Each fork was characterized into three separate sections: headwater (coolwater), middle (warmwater), and lower (coldwater). Springs were identified throughout each fork, with greatest concentrations in the lower sections of each fork. Using single-pass electrofishing, we sampled 61 sites across the three forks in the Whitewater River system (North = 21 sites, Middle = 19, South = 21), and catch statistics were used to calculate diversity, trout abundance, and trout condition. In general, diversity increased, and trout were healthier but less abundant in middle and headwater sections, whereas diversity decreased slightly, trout condition decreased, and trout abundance increased in lower reaches, with changes differing somewhat among forks. Canonical correlation analysis highlighted strong significant correlations showing that Simpson diversity and trout condition increase going upstream, with high non-trout abundance, while trout catch rates decrease and width narrows. The Whitewater River is a catchment exhibiting transitional temperature-pattern characteristics with generally low fish community diversity and trout conditions that range from thin, normal, and robust. Dominated by a changing landscape (agriculture) and intensifying climate change, we may begin to see stream temperatures increase along with species diversity. Understanding how spring temperature influences species composition and distribution can bring potential stressors to light, increasing our understanding of thermal conditions and helping to mitigate the negative impacts from land use and climate change. [ABSTRACT FROM AUTHOR]

Icing in cut slopes is a serious risk to transportation safety in cold regions. Research on the occurrence process and mechanism of icing is a prerequisite for proposing effective management measures. We took the cut slopes of the K162 section of the Beihei Highway as the research object. We used a combination of field investigation, geological exploration, monitoring, and simulation to study and analyze the power source, occurrence process, and triggering mechanism of icing in cut slopes. The results show that the geologic type of this cut slope is a mudstone–sandstone interaction stratum. Abundant shallow groundwater is the source of water for icing. The excavation of cut slopes extends the effect of negative temperatures on groundwater flow during the winter period. The process of ice formation in cut slopes can be described as follows: As the environmental temperature drops, the surface soil begins to freeze, resulting in a gradual narrowing of the water channel; then, the groundwater flow is blocked, so that the internal pressure begins to rise. When the internal pressure of the pressurized groundwater exceeds the strength of the frozen soil, groundwater overflows from the sandstone layer to the surface, forming icing. The high pore water pressure inside the cut slope is the precursor for the occurrence of icing. The dynamic pressure of the pore water pressure is the main driving force for the formation of icing in cut slopes. The obstruction of the water channel due to ground freezing is the triggering condition for ice formation in cut slopes. [ABSTRACT FROM AUTHOR]

Egypt is a country that heavily relies on agricultural activities. River Nile serves as the primary source of irrigation water for agricultural purposes. El Saieda Basin project, located in the southern western desert of Egypt, represents a massive agricultural project where irrigation water is distributed from the River Nile through an extensive network of canals. This study focuses on evaluating the groundwater resources, the groundwater quality, and the hydrochemical processes affecting the groundwater within El Saieda Basin to provide an additional source of irrigation water and to ensure a safe water supply for the residential villages. Various data sets were integrated, including geomorphology, geology, hydrogeology, hydrogeochemistry and stable isotopes. Based on the geomorphology; the study area includes four geomorphological units, Structural Plateau, Bajada Plain, Eroded old Nubian surface, and Nile alluvial Plain. According to the geology; the study area is located in the southern part of the Western Desert. The dominating geological units in this part of Egypt range in age from Lower Cretaceous to Recent. Regarding the hydrogeology of the study area; the Quaternary aquifer is the main aquifer in the study area where 24 groundwater samples plus two surface water samples (irrigation canal + main Drain) were collected and analyzed. Groundwater salinity classification shows that 17% of the total groundwater samples are fresh groundwater samples with values that range between 550 and 996 mg/l with an average of 775 mg/l. 29% of the total groundwater samples are brackish groundwater samples with values that range between 1177 and 2273 mg/l with an average of 1868 mg/l. In addition, 46% of the total groundwater samples are salty groundwater samples with values that range between 3197 and 4886 mg/l with an average of 4037 mg/l. The rest of the groundwater samples (8%) are saline groundwater samples with a maximum value of 9018 mg/l and an average of 7645 mg/l. The groundwater's temperature ranges from 25 to 30.9 C. However, the measured pH values showed relatively neutral water where the values range from 6.6 to 7.6. The relationship between salinity content and the other ions indicates that sodium, calcium, magnesium, sulfate, and chloride are the effective ions that increase the salinity content. Silicate weathering and dissolution of calcite are the main hydrochemical processes affecting the groundwater. From the saturation indices (SI) results it is indicated that Gypsum and Anhydrite dissolve with negative SI values, whereas iron minerals are supersaturated with positive values. Carbonate minerals are insufficiently soluble in groundwater, with values that fluctuate positively and negatively around zero. From the hypothetical salts, it is indicated that the quaternary groundwater aquifer in the study area is highly evolved as it's enriched with terrestrial and marine residuals indicated by the presence of NaCl, MgCl2, MgSO4, CaSO4, Ca(HCO3)2 salts. From the Environmental Stable Isotopes, it is indicated that all the groundwater samples are enriched by 18O and Deuterium which indicates a recharge from the main irrigation canal and return flow irrigation water. Trace elements results indicated that the groundwater is suitable for human drinking according to the World Health Organization and also for irrigation according to the Australian guidelines for irrigation water quality. [ABSTRACT FROM AUTHOR]

The anatomical characteristics of xylem and their relationship with temperature during the year can be studied at the cellular scale by using micro-coring technology and the wood anatomy method. In this study, we used Populus euphratica Oliv. trees with different groundwater burial depths in the lower Tarim River as the research subjects. Micro-core samples of Populus euphratica were collected near two sampling sites, TY1 and TY2, which have different groundwater burial depths. We analyzed the differences in xylem anatomical characteristics and their relationship with extreme temperatures under these varying groundwater conditions using wood anatomy methods. The results showed that the anatomical parameters at TY1, with a higher groundwater table, were greater than those at TY2, which had a lower groundwater table. Specifically, the conduit density, total conduit area, average conduit area and maximum conduit area of Populus euphratica xylem were significantly and positively correlated with both maximum and minimum temperatures. The principal components of xylem parameters at TY1, with the higher water table, were significantly and positively correlated with both maximum and minimum air temperatures. In contrast, the principal components of xylem parameters at TY2, with the lower water table, were not significantly correlated with either maximum or minimum air temperatures. The sensitivity analysis indicated that the sensitive maximum air temperature for the principal component parameter index change of Populus euphratica xylem was 34.1 °C, and the sensitive minimum air temperature was 16.1 °C. Therefore, different moisture conditions affected the sensitivity of xylem parameter growth to temperature, with the temperature threshold for Populus euphratica xylem growth being between 16.1 °C and 34.1 °C. [ABSTRACT FROM AUTHOR]

Braided rivers can provide substantial recharge to regional aquifers, with flow exchange between surface water and groundwater occurring at a range of spatial and temporal scales. However, the difficulty in measuring and modelling these complex and dynamic river systems has hampered process understanding and the upscaling necessary to quantify these fluxes. This is due to an incomplete understanding of the hydrogeological structures that control river–groundwater exchange. In this paper, we present a new conceptualisation of subsurface processes in braided rivers based on observations of the main losing reaches of three braided rivers in Aotearoa / New Zealand. The conceptual model is based on a range of data, including lidar, bathymetry, coring, particle size distribution, groundwater level and temperature monitoring, radon-222, electrical-resistivity tomography and fibre-optic cables. The combined results indicate that sediments within the recently active river braidplain are distinctive, with sediments that are poorly consolidated and better sorted compared with adjacent deposits from the historical braidplain that become successively consolidated and intermixed with flood silt deposits due to overbank flow. A distinct sedimentary unconformity, combined with the presence of geomorphologically distinct lateral boundaries, suggests that a "braidplain aquifer" forms within the active river braidplain through the process of sediment mobilisation during flood events. This braidplain aquifer concept introduces a shallow storage reservoir to the river system, which is distinct from the regional aquifer system, and mediates the exchange of flow between individual river channels and the regional aquifer. The implication of the new concept is that surface water–groundwater exchange occurs at two spatial scales: the first is hyporheic and parafluvial exchange between the river and braidplain aquifer; the second is exchange between the braidplain aquifer and regional aquifer system. Exchange at both scales is influenced by the state of hydraulic connection between the respective water bodies. This conceptualisation acknowledges braided rivers as whole "river systems", consisting of channels and a gravel aquifer reservoir. This work has important implications for understanding how changes in river management (e.g. surface water extraction, bank training and gravel extraction) and morphology may impact groundwater recharge (and potentially flow, temperature attenuation and ecological resilience) under dry conditions. [ABSTRACT FROM AUTHOR]

The main objective of this research was to develop a geological and geophysical modeling to infer the geometry and thickness in the sedimentary sequence of the middle basin of the Bogotá River with emphasis on the Guadalupe Group, reconstructing the stratigraphic sequence, structural setting, hydrogeological modeling, and potential geothermal uses. Various geophysical methods were applied, including vertical electrical soundings (VES), and magneto telluric soundings (MT-VES), whose results were complemented with the interpretation of seismic lines, regional and local gravity anomaly maps, and borehole data, among others, which allowed to model the subsurface from the surface to depths beyond 3000 meters, with emphasis on the interval between 500m to 1000m depth. Integrated models were developed from interpretations of electrical resistivity data, gravity and magnetic data, reflection seismic and borehole data. Based on the results, potential deep aquifers have been proposed to be confirmed by drilling. These deep aquifers can contribute to satisfy the need for water, which historically has been explored and overexploited from shallower aquifers in this sector of the basin. A recommendation was also made to consider the potential of low enthalpy thermal energy for agro-industrial purposes associated with groundwater's temperature at the depth of this research. As a result, the modeled sedimentary sequence is characterized by a thick quaternary overburden overlying an intensively folded and faulted Neogene, Paleogene, and upper Cretaceous formations, mainly composed of siltstone, sandstones, and shale sequences of fluvial and marine environment, including facies of marine regressions and transgressions near the coastline. The penetration obtained allows establishing a high hydrogeological potential in the first 2000m depth, especially associated with the Guadalupe group, where the Labor and Tierna and Arenisca Dura formations have the highest hydrogeological potential. In addition, the preliminary estimation of thermal gradients suggest that low enthalpy geothermal energy potential is feasible to be used for the agro-industrial demand of energy of the study area. [ABSTRACT FROM AUTHOR]

The Dinaric karst in the north differs from the rest of the karst in Croatia in terms of karstification depth. The infiltrating precipitation drains in cascades from deeply karstified mountainous areas to the shallow or fluviokarst, forming the tributaries of the Kupa River. Time series analyses were conducted on a 5-year dataset to elucidate the hydrogeological conceptual model of the area and clarify disparate findings from tracer tests under varying hydrological conditions. The flow duration curve, autocorrelation functions, and recession curves were used to evaluate the spring discharge variability, the karstification degree, and the karst aquifer's size. The crosscorrelation function and temperature dynamics were employed to assess the spring's response to recharge and the hydrogeological system behavior. Comparative analysis with previous studies was conducted to contextualize the obtained results. The research outcomes delineated several key findings: (i) the deep karst zone is less developed than the shallow karst zone; (ii) groundwater exchange is significantly faster in shallow karst; (iii) groundwater divides in the Kapela Mountain are zonal; (iv) the homogenization of groundwater occurs during periods of high water levels; (v) fast water exchange transpires without concurrent groundwater temperature homogenization; and (vi) a definition of the boundary between deep and fluviokarst in Croatia. [ABSTRACT FROM AUTHOR]

The application of green energy resources is gaining increasing attention in the field of engineering. In cold areas, the groundwater circulation temperature control system (GCTCS) can serve as an auxiliary structure to the bridge deck on highways, effectively preventing the pavement surface from freezing. In this study, a finite element simulation is conducted to establish a bridge structure model of the GCTCS, incorporating both steady-state and transient conditions to investigate its anti-icing performance. Additionally, the influences of various factors, such as wind speed, asphalt concrete layer thickness, groundwater temperature, pipe water flow rate, and pipe spacing, on the temperature of the water film on the pavement surface are investigated and validated through laboratory testing. The results demonstrate that wind speed has a significant influence, with the convective heat loss reaching 90% when the wind speed reaches 10 m/s. Groundwater temperature is the second most influential factor, showing a linear relationship with the water film temperature. Excessive pipe spacing can lead to an uneven temperature distribution on the pavement surface. The thickness of the asphalt concrete layer and the flow rate have minimal effects. However, a low flow rate can result in a significant decrease in the water film temperature. Furthermore, changes in the thermal conductivity of the surface layers also contribute to the anti-icing effect. The simulation analysis of the GCTCS provides valuable guidance for practical engineering in cooler regions where groundwater resources are abundant. [ABSTRACT FROM AUTHOR]

Thermal energy is utilized as an environmentally friendly energy source for seasonal heat and cold storage on a global scale. Specifically, the aquifer thermal energy storage system is highlighted for being cost-effective in cooling and heating applications. The study assesses the sustainability of the aquifer thermal energy storage in the Halabja-Khurmal sub-basin by evaluating six critical criteria: groundwater transmissivity, groundwater temperature, groundwater discharge, groundwater chemistry, population density, and per capita GDP. A multi-criteria decision analysis judgment is applied to analyze all criteria, resulting in a consistency ratio of 0.3% in the analytical hierarchy process. Consequently, the sustainability map for Aquifer Thermal Energy Storage in the Halabja-Khurmal sub-basin for heating reveals that 26.45% of the area is strongly sustainable located in the north and southwestern part of the sub-basin, 73.53% is moderate in the east, central, southeast, and southern regions, 0.02% is weakly sustainable as a tiny area in the southwestern. On the other hand, the sustainability map for Aquifer Thermal Energy Storage in the Halabja-Khurmal sub-basin for cooling reveals that 19% of the area is strongly sustainable located in the north, and southwestern parts of the sub-basin, 78% is moderate in the northeast, east, southeast, west, central, and southern regions, 3% is weakly sustainable as spots in the west and southwestern areas. [ABSTRACT FROM AUTHOR]

Investigating the repercussions of climate change and irrigation timing on groundwater contamination necessitates thorough examination of the fluctuations in seawater and groundwater recharge temperature. This study introduces an innovative numerical approach to analyze groundwater salinity and temperature dynamics across three distinct scenarios using the SEAWAT code based on Henry's problem. The first scenario delves into the impact of seawater temperature, the second focuses on the consequences of aquifer freshwater recharge temperature, and the third amalgamates the effects of both scenarios. Remarkably, the study reveals that saltwater intrusion (SWI) experiences a decline attributable to the aquifer's heightened seawater temperature and the diminished inland freshwater temperature. Furthermore, combining these two scenarios has a more pronounced effect on aquifer pollution; the temperature-induced changes in SWI for this third scanrio reach + 8.10%, + 12.70%, + 16.20%, + 24.90%, + 28.30%, and + 31.80% compared to the case without considering the temperature effect. Notably, our results propose a potential strategy to mitigate SWI by introducing cold freshwater recharge into aquifers, such as irrigation at night time when water temperature is low. This innovative approach underscores the interconnectedness of various environmental factors. It provides a practical avenue for proactive intervention in safeguarding groundwater quality against the adverse impacts of climate change and irrigation practices. [ABSTRACT FROM AUTHOR]

Abstract Thermal energy is utilized as an environmentally friendly energy source for seasonal heat and cold storage on a global scale. Specifically, the aquifer thermal energy storage system is highlighted for being cost-effective in cooling and heating applications. The study assesses the sustainability of the aquifer thermal energy storage in the Halabja-Khurmal sub-basin by evaluating six critical criteria: groundwater transmissivity, groundwater temperature, groundwater discharge, groundwater chemistry, population density, and per capita GDP. A multi-criteria decision analysis judgment is applied to analyze all criteria, resulting in a consistency ratio of 0.3% in the analytical hierarchy process. Consequently, the sustainability map for Aquifer Thermal Energy Storage in the Halabja-Khurmal sub-basin for heating reveals that 26.45% of the area is strongly sustainable located in the north and southwestern part of the sub-basin, 73.53% is moderate in the east, central, southeast, and southern regions, 0.02% is weakly sustainable as a tiny area in the southwestern. On the other hand, the sustainability map for Aquifer Thermal Energy Storage in the Halabja-Khurmal sub-basin for cooling reveals that 19% of the area is strongly sustainable located in the north, and southwestern parts of the sub-basin, 78% is moderate in the northeast, east, southeast, west, central, and southern regions, 3% is weakly sustainable as spots in the west and southwestern areas.

Hydrothermal geothermal energy, as a widely distributed, large reserve and easily exploitable renewable source, can be used for both power generation and building heating. In this study, a numerical simulation of heat extraction performance is conducted based on monitoring well temperature data in a geothermal field in Xiong'an New Area. The effects of the reinjection temperature, injection flow rate, and reinjection rate on the outlet temperature and the reservoir temperature during a long-term operation are analyzed. The results indicate that the lower reinjection temperature can generate a critical disturbance scope for the thermal reservoir during the exploitation process. The impact scope on the thermal reservoir can reach 210.3 m at a reinjection temperature of 25 °C, which is not conducive to maintaining the outlet temperature of production wells in the long-term. The reinjection rate significantly affects both the horizontal and vertical temperature fields of the thermal reservoir. Under reinjection conditions of 30 °C and 40 kg/s, the horizontal and vertical impact scope of the thermal reservoir are 262.3 and 588.5 m, respectively. The reinjection rate is inversely related to the outlet temperature. A decrease from 100% to 70% in the reinjection rate can increase the outlet temperature by 4.21%. However, a decrease in the reinjection rate will lead to a decline in the groundwater level. Therefore, balancing the variation in outlet temperature and groundwater level is crucial in practical engineering. [ABSTRACT FROM AUTHOR]

Alluvial aquifers often exhibit highly conductive embedded formations that can act as preferential pathways for the transport of solutes. In this context, a detailed subsurface characterization becomes crucial for an effective monitoring of groundwater quality and early detection of contaminants. However, small-scale heterogeneities are seldom detected by traditional nondestructive investigations. Heat propagation in porous media can be a relatively inexpensive tracer for groundwater flow, potentially offering valuable information in various applications. In this study, we applied passive Fiber Optics Distributed Temperature Sensing (FO-DTS) to a group of observation wells in a highly heterogeneous phreatic aquifer to uncover structures with different hydraulic conductivity, relying on their response to temperature fluctuations triggered by natural and anthropogenic forcings. A comprehensive data analysis approach, combining statistical methods and physics-based numerical modeling, allowed for a three-dimensional characterization of the subsurface at the experimental site with unprecedentedly high resolution. [ABSTRACT FROM AUTHOR]

Accretionary prisms are composed mainly of ancient marine sediment scraped from the subducting oceanic plate at convergent plate boundaries. Anoxic groundwater is stored in deep aquifers associated with accretionary prisms and can be collected via deep wells. We investigated how such groundwater pumping affects the microbial community in a deep aquifer. Groundwater samples were collected from a deep well drilled down to 1500 m every six months (five times in total) after completion of deep well construction and the start of groundwater pumping. Next-generation sequencing and clone-library analyses of 16S rRNA genes were used to describe the subterranean microbial communities in the samples. The archaea: the prokaryote ratio in groundwater increased significantly from 1 to 7% (0 and 7 months after initiating groundwater pumping) to 59 to 72% (13, 19, and 26 months after initiating groundwater pumping), and dominant prokaryotes changed from fermentative bacteria to sulfate-reducing archaea. The optimal growth temperature of the sulfate-reducing archaea, estimated based on the guanine-plus-cytosine contents of their 16S rRNA genes, was 48–52 °C, which agreed well with the groundwater temperature at the deep-well outflow. Our results indicated that, in deep aquifers, groundwater pumping enhances groundwater flow, and the supply of sulfate-containing seawater activates the metabolism of thermophilic sulfate-reducing archaea. [ABSTRACT FROM AUTHOR]

As our planet faces the complex challenges of global climate change, understanding and effectively communicating critical environmental indicators have become critical. This study explores the importance of reporting groundwater temperature data as a key component in understanding the broader implications of climate change with the use of new graphical tools. More specifically, the use of the groundwater temperature (GWT) stripes and bi-plots of GWT anomalies vs. time was proposed. For an in-depth examination of this subject, monitoring wells situated in the Piedmont Po plain (NW Italy) were selected, with available daily groundwater temperature data dating back to 2010. All data refer to the groundwater of the shallow unconfined aquifer within alluvial deposits. From the analyses of both GWT stripes and the bi-plot of GWT anomalies vs. time, it was possible to identify a general increase in the positive anomaly, corresponding to an increase in GWT in time in almost all of the monitoring points of the Piedmont plain. Furthermore, the utilisation of GWT stripes demonstrated the capability to effectively portray the trend of the GWT data relative to a specific point in a readily understandable manner, facilitating easy interpretation, especially when communicating to a non-scientific audience. The findings underline the urgent need to improve GWT data search and communication strategies to disseminate valuable information to policy makers, researchers, and society. By illustrating the intricate interplay between groundwater temperature and climate change, this research aims to facilitate informed decision-making and promote a proactive approach towards climate resilience. [ABSTRACT FROM AUTHOR]

The groundwater characteristics of the Učja aquifer were investigated using geochemical and isotopic data. The water discharge and physico-chemical properties of the groundwater and the Učja River ref lect the climate that is characteristic of the area. The mixed snow/rainfall regime is characteristic for the Učja Valley, with the highest discharges appearing during the spring snowmelt and autumn precipitation, and the lowest discharges in the winter and especially summer months. The temperature of the groundwater and the Učja River is lower in winter and higher in summer. The specific electrical conductivity values indicate a very permeable carbonate aquifer. Higher conductivity values were observed in spring and autumn at all sampling sites, which is related to snowy and rainy periods. The groundwater from the Učja aquifer indicates a uniform type of water (Ca-Mg-HCO3), with Ca2+, Mg2+ and HCO3 - the most abundant ions. Differences in Ca2+ and Mg2+ concentrations and in the Mg2+/Ca2+ molar ratio between sampling sites were observed. Those springs with lower Mg2+ and lower Mg2+/Ca2+ molar ratios indicate limestone recharge areas, and those springs with higher Mg2+ and molar ratios indicate interaction with the dolomite hinterland. The pH values confirm alkaline waters characteristic of carbonate aquifers. The hydrogen (δ²H) and oxygen (δ18O) isotope values suggest the main source of water is from precipitation from a complex mixing of maritime and continental air masses. An altitude isotopic effect is observed with minor δ18O and δ²H depletion at higher altitude sampling sites compared to those springs at lower altitudes. The altitude isotopic effect is most prominent in spring. The δ13CDIC values indicate the dissolution of carbonates and the degradation of organic matter. [ABSTRACT FROM AUTHOR]

This study presents a 25 ka reconstruction of the Pleistocene paleoclimate in the South German Molasse Basin. Deep groundwater was sampled at 19 wells in the Upper Jurassic aquifer (UJA). Calculating gas temperatures (NGT) using the UA model with the noble gases Ar, Kr, and Xe led to groundwater recharge temperatures between 0.4 and 4.7°C. Combined with innovative 14CDOC groundwater dating, calculated NGTs revealed up to 8°C cooler soil temperatures during the Pleistocene compared with modern soil temperature. This interpretation agrees well with the observed depleted stable water isotope signature ranging from −83.3 to −86.1 for δ2H and from −10.66 to −11.77 for δ18O, which is characteristic of groundwater of Pleistocene origin in Southern Germany. The temperature differences (∆T) agree remarkably well with calculated NGTs within other European basins (∆T 6–9.5°C) and suggest widespread pronounced terrestrial cooling during the Last Glacial Maximum through the interior of the European continent. Plain Language Summary: To characterize the climate in Southern Germany during the last ice age, we first determined 14CDOC for dating the deep groundwater of the Upper Jurassic aquifer. Subsequently, we looked closer at noble gases and stable water isotopes. The contents in groundwater are mainly controlled by temperature when the groundwater is in contact with the atmosphere during the formation on the earth's surface. Our results show that the calculated noble gas temperatures during this time were up to 8°C colder than modern temperatures. Our findings help to gain a better understanding of Earth's climatic history. Key Points: The noble gas temperatures from deep groundwater in Southern Germany show substantial cooling up to 8°C during the PleistoceneNoble gas temperatures in combination with groundwater dating using the 14CDOC method are helpful for reconstructing the paleoclimateThe deep groundwater in the Upper Jurassic aquifer may be a mixture of meteoric water and Pleistocene glacial meltwater [ABSTRACT FROM AUTHOR]

Rural communities in Mexico and other countries with limited economic resources require a low-cost measurement system for the piezometric level and temperature of groundwater for their sustainable management, since anthropogenic action (pumping extractions), natural recharge and climate change phenomena affect the behavior of piezometric levels in the aquifer and its sustainability is at risk. Decrease in the piezometric level under a balanced level promotes salt intrusion from ocean water to the aquifer, salinizing and deteriorating the water quality for agriculture and other activities; and a decrease in water level under the pumps or well drilling depth could deprive communities of water. Water temperature monitoring is essential to determine electric conductivity and dissolved salt content in groundwater. Using IoT technology, a device was developed that monitors both variables inside the well, and the ambient temperature and atmospheric pressure outside the well. The measurements are made in real time, with sampling every second and sending data to a dedicated server every 15 min so that the visualization can be accessed through a device with Internet access. The time series of the variables measured inside and outside the well were obtained over a period of three months in the rural community of Agua Blanca, Guasave, Sinaloa, Mexico. Through these records, a progressive temporary drawdown of the piezometric level is observed, as well as the frequency of pumping. This low-cost IoT system shows potential use in hydrological processes of interest such as the separation of regional and local flow, drawdown rates and recognition of geohydrological parameters. [ABSTRACT FROM AUTHOR]

The groundwater temperature is an important indicator of groundwater dynamic change. Therefore, comprehensively monitoring groundwater temperature, understanding its temporal and spatial distribution characteristics, and studying its change rule can not only reflect the hydrogeological characteristics of groundwater system, but also provide a basis for its identification and division. With an elevation of 3,500 m--2,400 m, the Heilongtan groundwater system of Lijiang, Yunnan Province is a typical mountain and basin landform with wide distribution of soluble rocks, strong development of karst, and combination of faults and folds. Its hydrogeological environment is complex, challenging the delimitation of spring area and groundwater system. Because the study area is located in the plateau mountainous area, and the temperature field of karst groundwater can also reflect the variation of groundwater temperature at different elevations in the mountain and canyon areas on the plateau, this study has a great referential significance for the research of groundwater in other similar areas. Based on previous research results as well as a large number of monitoring data on groundwater temperature obtained in the study area from June to November, 2018, the spatial-temporal variation characteristics of groundwater temperature in the spring area and the variation characteristics of borehole water temperature were compared and analyzed, and the indicative significance of these two types of variation characteristics were discussed. Meanwhile, the feasibility of system division of the Heilongtan spring area was verified. The results show that there is a good spatial correlation between the elevation of groundwater level and temperature, and the groundwater temperature in the recharge area at high altitude is low. From the recharge area to the discharge area, the water temperature experiences a gradual upward trend. The water temperature in the discharge area can also indicate the circulation of groundwater runoff. The lower the water temperature in the discharge area is, the smoother groundwater becomes. In terms of time, as groundwater receives a large amount of rainfall recharge during the flood season, the circulation of groundwater flow increases, which may result in a short storage time of water and the phenomenon that the groundwater temperature in the discharge area is closer to that in the recharge area and that the overall water temperature decreases. At the end of the flood season, as rainfall decreases, the circulation of groundwater flow weakens, and the underground water temperature in the discharge area rises in different degrees. In a certain depth below the surface, the groundwater temperature does not completely conform to the theoretical law that the temperature rises gradually with the increase of depth, On the contrary, the groundwater temperature will remain unchanged or decrease gradually with the increase of depth, the reasons of which can be summarized as follows. (1) The temperature of surface water formed by precipitation is higher than that of groundwater, and the groundwater will be heated during infiltration and recharge. (2) When a deep karst pipeline is developed, the groundwater will "wash" away the heat from the deep, and the groundwater temperature will decrease with the increase of depth. (3) If the vertical movement of groundwater is intense, with large up-and-down disturbances and good temperature exchange conditions, the temperature value will become relatively stable in this active zone. This phenomenon is found in all monitoring points in the discharge area, especially in the period of smooth groundwater flow. (4) Under the influence of solar radiation energy, the surface temperature shows diurnal and seasonal variations. The diurnal variation affects 1--2 m below the surface, and the seasonal variation affects 30 m below the surface. This study shows that there are similarities and differences in the groundwater temperature in the study area, and the groundwater temperature is a good indication for the delimitation of groundwater system. This study also verifies the rationality of the existing delimitation system in the study area. [ABSTRACT FROM AUTHOR]

The impacts of climate change-induced warming on our ecosystems can no longer be neglected, but our understanding of consequences for groundwater ecosystems in general and groundwater quality in particular is alarmingly incomplete. In this review, we therefore provide an overview of the current state of knowledge related to the impact of global warming on our precious groundwater resources. Groundwater warming in shallow aquifers is closely associated with increasing average land surface temperatures and has already reached + 1 K compared to pe-industrial times. Until the end of the twenty-first century, temperature increases in local groundwater of up to + 10 K are possible. Monitoring data, laboratory and field experiments all provide evidence that such temperature increases are sufficient to substantially modify groundwater quality through numerous and interlinked biogeochemical processes, which we have summarized in a conceptual overview. Warming impacts on groundwater are highly site-specific and spatially heterogeneous, which complicates their assessment and prediction. Locally, shallow unconfined and nutrient-rich floodplain aquifers are most susceptible to warming-induced changes. Importantly, processes affecting water quality are not only modified by a long-term rise in groundwater temperatures, but also in the short-term during weather extremes, which is of great relevance for riverbank filtration. At the regional scale, aquifers in cold regions impacted by permafrost thawing are especially vulnerable to warming. As the majority of temperature-sensitive processes affecting groundwater quality are not or only very slowly reversable, we pressingly require comprehensive mechanistic understanding before it is too late to develop suitable countermeasures and management strategies. [ABSTRACT FROM AUTHOR]

Groundwater (GW) is sensitive to climate change (CC), and the effects have become progressively more evident in recent years. Many studies have examined the effects of CC on GW quantity. Still, there is growing interest in assessing the qualitative impacts of CC, especially on GW temperature (GWT), and the consequences of these impacts.This study aimed to systematically review recently published papers on CC and GWT, determine the impacts of CC on GWT, and highlight the possible consequences.The Scopus and Web of Science databases were consulted, from which 144 papers were obtained. After an initial screening for duplicate papers, a second screening based on the titles and abstracts, and following an analysis of topic applicability to this subject after examining the full text, 44 studies were included in this review. The analysed scientific literature, published in 29 different journals, covered all five continents from 1995 to 2023.This review indicated that the subject of GWT variations due to CC is of global interest and has attracted significant attention, especially over the past two decades, with many studies adopting a multidisciplinary approach. A general increase in GWT was noted as a primary effect of CC (especially in urban areas); furthermore, the implications of this temperature increase for contaminants and GW-dependent ecosystems were analysed, and various applications for this increase (e.g. geothermal) were evaluated.This review highlights that GWT is vulnerable to CC and that the consequences can be serious and worthy of further investigation.

The relationship between the soil surface temperature and groundwater level is complex and influenced by various factors. As the soil surface temperature increases, water evaporates quickly from the soil, which can lead to a decrease in the groundwater level. In this study, we analyzed the impact of soil surface temperature on changes in the groundwater level in the Bukhara region of Uzbekistan using data from 1991 to 2020. The Bukhara region experiences regular water shortages, increased soil salinization, and inefficient energy in lift-irrigated areas, which is a typical constellation of challenges to the water–energy–food–environment (WEFE) nexus. The soil surface temperature data were collected from the Hydrometeorological Service Agency, whereas groundwater level data were obtained from the database of the Amelioration Expedition under the Amu-Bukhara Basin Irrigation Systems Authority. We used linear regression analysis and Analysis of Variance (ANOVA) tests to establish the significance of the relationship between the soil surface temperature and groundwater level, as well as the impact of the location of the groundwater level measurements. The results indicate that the model was a good fit to the data, and both the intercept and the soil surface temperature were significant factors that affected groundwater level. The results further suggest that the strength of the relationship between solar radiation and soil surface temperature is very high, with a correlation coefficient of 0.840. This means that when solar radiation increases, soil surface temperature also tends to increase. The analysis also showed that 53.5% of the changes in groundwater level were observed by the regression model, indicating a moderately correlated relationship between the groundwater level and soil surface temperature. Finally, higher solar radiation leads to higher soil surface temperature and higher evapotranspiration rates, which can lead to a decrease in groundwater level. As a result, we observe that the soil surface temperature determines changes in the groundwater level in the study region. [ABSTRACT FROM AUTHOR]

The Gulf of Maine hosts the southernmost remaining population of North American Atlantic salmon. Despite extensive hatchery supplementation since the late 1800s, and more recent riverine habitat restoration efforts and fishing restrictions, US-origin Atlantic salmon populations continue to decline and have remained at low abundance over recent decades. Climate change has been identified as a critical threat to the future of US Atlantic salmon. In this study, we synthesized available information on how habitats used by Atlantic salmon across all their life stages will be affected by climate change as well as the suitability of future conditions for salmon's persistence in the region. Maintaining sufficient cool water refugia during increasing summer temperatures in riverine habitats is required for sustaining salmon in the future. Changes in groundwater quantity and temperature, which will depend on future precipitation and temperature, will be critical factors for river temperatures, as will land use and land cover. While Atlantic salmon's freshwater life stages are heavily documented, the marine phase is relatively less studied. Climate models predict basin-scale changes over the next century, but impacts to salmon are difficult to predict. Furthermore, disparate drivers and differential rates of change between freshwater and marine habitats could present an obstacle to the transition between phases in the future. We have a general understanding of migration patterns and prey preferences but lack a clear picture of how salmon respond to habitat and ecosystem-level changes associated with climate change progression. More research to understand freshwater habitat changes and salmon's marine spatiotemporal distribution responses will enhance capacities to evaluate future risks and predict impacts of climate change to US-origin Atlantic salmon. [ABSTRACT FROM AUTHOR]

Groundwater temperature is one of the main factors that is considered when deciding on installation of a vapor compression refrigeration system with groundwater used for heat transfer. Groundwater temperature measurement is a necessity for the system installation. A total of 75 groundwater wells within the Chiang Mai Basin were selected for temperature monitoring stations. The temperature-depth profile of shallow groundwater showed that temperature had little change below 2 m depth from the water table. The temperature-depth profile of deep groundwater showed the separation of upper and lower temperature zones. Mostly, the temperature of the upper zone of deep groundwater has a positive slope. The temperature of the lower zone of deep groundwater is relatively constant. Both the shallow and deep groundwater temperatures are below the atmospheric temperature. The seasons, hydrogeologic units, and land use types have affected groundwater temperature of the Chiang Mai Basin only little. [ABSTRACT FROM AUTHOR]

A high concentration of fluoride (F−) in drinking water is harmful and is a serious concern worldwide due to its toxicity and accumulation in the human body. There are various sources of fluoride (F−) and divergent pathways to enter into groundwater sources. High F− incidence in groundwater was reported in Raigarh district of Central India in a sedimentary (Gondwana) aquifer system. The present study investigates the hydrogeochemistry of groundwater in the Tamnar area of Raigarh district to understand the plausible cause(s) of high F− concentration, especially the source(s) and underlying geochemical processes. Groundwater samples, representing pre-monsoon (N = 83), monsoon (N = 20), and post-monsoon (N = 81) seasons, and rock samples (N = 4) were collected and analyzed. The study revealed that (i) groundwater with high F− concentration occurs in the Barakar Formation, which has a litho-assemblage of feldspathic sandstones, shales, and coal, (ii) high F− concentration is mainly associated with Na-Ca-HCO3, Na-Ca-Mg-HCO3, and Na-Mg-Ca-HCO3 types of groundwater, (iii) the F− concentration increases as the ratio of Na+ and Ca2+ increases (Na+: Ca2+, concentration in meq/l), (iv) F− has significant positive correlation with Na+ and SiO2, and significant negative correlation with Ca2+, Mg2+, HCO3−, and TH, and (v) high F− concentration in groundwater is found in deeper wells. Micas and clay minerals, occurring in the feldspathic sandstones and intercalated shale/clay/coal beds, possibly form an additional source for releasing F− in groundwater. Feldspar dissolution coupled with anion (OH− or F−) and cation (Ca2+ for Na+) exchange are probably the dominant geochemical processes taking place in the study area. The higher residence time and temperature of groundwater in deeper aquifers also play a role in enhancing the dissolution of fluorine-bearing minerals. Systematic hydrogeochemical investigations are recommended in the surrounding area having a similar geologic setting in view of the potential health risk to a large population. [ABSTRACT FROM AUTHOR]

The ability to accurately assess the impact of organic soil drainage on greenhouse gas emissions (GHG) is still limited. Methane (CH4) emissions are characterized by significant variations, and GHG emissions from nutrient-rich organic soil in the region have not been extensively studied. The aim of this study was to assess CH4 and nitrous oxide (N2O) emissions from nutrient-rich organic soil in hemiboreal forests to provide insights into their role in regional GHG balance. Over the course of one year, CH4 and N2O emissions, as well as their affecting factors, were monitored in 31 forest compartments in Latvia in both drained and undrained nutrient-rich organic soils. The sites were selected to include forests of different ages, dominated by silver birch (Betula pendula Roth), Norway spruce (Picea abies (L.) Karsten), and black alder (Alnus glutinosai (L.) Gärtner), as well as clearcuts. Soil GHG emissions were estimated by collecting gas samples using the closed manual chamber method and analyzing these samples with a gas chromatograph. In addition, soil temperature and groundwater level (GW) measurements were conducted during gas sample collection. The mean annual CH4 emissions from drained and undrained soil were −4.6 ± 1.3 and 134.1 ± 134.7 kg CH4 ha−1 year−1, respectively. N2O emissions from undrained soil (4.1 ± 1.4 kg N2O ha−1 year−1) were significantly higher compared to those from drained soil (1.7 ± 0.6 kg N2O ha−1 year−1). In most of the study sites, undrained soil acted as a CH4 sink, with the soil estimated as a mean source of CH4, which was determined by one site where an emission hotspot was evident. The undrained soil acted as a CH4 sink due to the characteristics of GW level fluctuations, during which the vegetation season GW level was below 20 cm. [ABSTRACT FROM AUTHOR]

When it comes to greenhouse gas (GHG) reduction, the role of water tables in former peat extraction areas has received considerable interest in recent decades. This study analysed the carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) surface-to-atmosphere fluxes from a rewetted and permanently flooded former peat extraction areas in comparison to pristine peatland in hemiboreal Latvia. Measurements of GHG fluxes combined gas sampling using a closed-chamber (opaque) method with the gas chromatography detection method. Among the studied land-use types, the highest annualised CO2 fluxes (soil heterotrophic and autotrophic respiration) were recorded in rewetted former peat extraction areas with restored vegetation and in undisturbed peatland (4.10 ± 0.21 and 3.45 ± 0.21 t CO2-C ha−1 yr−1, respectively), with the lowest in flooded former peat extraction areas (0.55 ± 0.05 t CO2-C ha−1 yr−1); temperature and groundwater level were found to be significant influencing factors. The highest annualised CH4 fluxes were recorded in undisturbed peatland (562.4 ± 155.8 kg CH4-C ha−1 yr−1), followed by about two-fold and ~20-fold smaller CH4 fluxes in flooded and rewetted areas, respectively. N2O fluxes were negligible in all the studied land-use types, with the highest N2O fluxes in undisturbed peatland (0.66 ± 0.41 kg N2O-N ha−1 yr−1). [ABSTRACT FROM AUTHOR]

The interaction of surface water and groundwater is important in the ecology of coastal basins, affecting hydrological conditions, oxygen regime, carbon, and nutrient exchange. This study demonstrates a dynamic connection between the salt-wedge region and its underlying aquifer in the eutrophic estuary. In winter, this estuary is covered with ice, and the river flow is at its lowest; that is why the specific response to groundwater discharge is best marked in this season. Groundwater admixture was detected in the salt-wedge region by highly active radium isotopes: 223Ra—4.80 ± 0.42 dpm 100 L−1, 224Ra—55.37 ± 1.1 dpm 100 L−1, and 228Ra—189.71 ± 4.66 dpm 100 L−1. The temperature of groundwater and river water was about +4 °C and 0 °C, respectively; that of seawater was −1.6 °C, and temperature increased up to +2.3 °C in the surface water–groundwater interaction region. Groundwater admixture is accompanied by a lower level of oxygen concentration of 52 μmol/kg; at that time, the maximum oxygen concentration in the salt-wedge region was 567 μmol/kg. In waters with a high activity of radium isotopes, there was a maximum partial pressure of CO2—4454 μatm at the range 100–150 μatm in the salt-wedge region and also observed extremum of NH 4 + , NO 2 − , and dissolved phosphorus. The surface water–groundwater interaction through anoxic sediment can form localized anaerobic areas despite the general oxygen supersaturation of eutrophic estuary waters and also cause local recycling of nutrients from bottom sediments. [ABSTRACT FROM AUTHOR]

Low-enthalpy geothermal energy (LEGE) is a carbon-free and renewable source to provide cooling and heating to infrastructures (e.g. buildings) by exchanging their temperature with that of the ground. The exchange of temperature modifies the groundwater temperature around LEGE installations, which may contribute to enhancing the capacity of aquifers to degrade organic contaminants of emerging concern (OCECs), whose presence is significantly increasing in urban aquifers. Here, we investigate the impact of LEGE on OCECs and their bioremediation potential through numerical modelling of synthetic and real-based cases. Simulation results demonstrate that: (i) LEGE facilities have the potential to noticeably modify the concentrations of OCECs; and (ii) the final impact depends on the design of the facility. This study suggests that optimized LEGE facility designs could contribute to the degradation of OCECs present in urban aquifers, thus improving groundwater quality and increasing its availability in urban areas. [ABSTRACT FROM AUTHOR]

The quality of groundwater has been severely impacted by urbanization around coasts. The change in climate and land use patterns has deteriorated the quality and availability of groundwater. One of the main issues in contemporary groundwater quality research is dissolved organic carbon (DOC) in the water. The influence of DO, water level and water temperature on DOC in groundwater was identified in the current study by sampling 68 groundwater samples. The analytical results revealed that ~18% of total samples have DOC > 5 mg/L. The groundwater samples represented in the urban regions show high DOC. The samples with higher DOC correlated positively with dissolved inorganic ions, such as Ca, K, NO3, Fe and DO. Domestic wastewater, agricultural runoff and local geology all have an impact on the DOC of groundwater. Groundwater chemistry is shown to be controlled by both aerobic and anaerobic conditions based on the DOC's interactions with other ions. The study interrelates various sources, such as land use, geology, water level and temperature, to the DOC in groundwater and infers that the levels are higher in shallow groundwater, predominantly around the built-up region followed by the agricultural region. The temperature changes enhance the DOC in groundwater due to the variation in microbial activity. The shallow water level with a lower temperature shows the maximum DOC. Apart from the sediment organic matter and microbes, the study also attributes land use pattern to the source of DOC in groundwater. [ABSTRACT FROM AUTHOR]

Shallow geothermal energy (SGE) is a renewable energy source that has the advantage of being low-cost, clean, and locally sourced compared to fossil fuels, and is thus significant for China to achieve its future goals of carbon peaking and carbon neutrality. However, determining how to improve the operational efficiency of SGE systems is a key factor in the sustainable development and utilization of geothermal energy. This study examined the long-term operational efficiency of SGE systems and applied numerical simulation methods of hydro-thermal coupling to a SGE utilization project in Shandong Province, China. The effect of the distribution of pumping and injection wells on the operation efficiency of the SGE system was analyzed, and the parameter of operation efficiency, defined by the ratio of the practical minable shallow geothermal energy to the theoretical shallow geothermal energy, was applied to quantify the operation efficiency of the SGE system. The simulated results show that the phenomenon of heat transfixion is significant in the current operation scheme, where one of three pumping wells is located downstream of the study area, which indicates that the local groundwater flow field mainly controls the operation efficiency of the SGE system. In the optimized operation scheme, the distribution of pumping and injection wells can be adjusted according to the feature of groundwater flow and temperature fields. The degree of heat transfixion significantly declines and the operation efficiency increases by 71.5%. In addition, further improvements in the operational efficiency of the SGE system can be considered through the running time. The findings of this paper will be useful for the construction and management of SGE systems. [ABSTRACT FROM AUTHOR]

In order to analyze the rationality of the compound well structure and the degree of heat penetration of groundwater in a groundwater ground source heat pump project in a certain district of a city, the author proposed a method for building energy consumption simulation and groundwater flow numerical model. The variation trend of groundwater temperature under different heat transfer temperature difference is simulated and predicted. The experimental results show that the fitting points where the error between the simulated predicted temperature and the actual measured temperature does not exceed 0.5 1 account for 51.7%, the fitting points where the error is 0.5~1 account for 28.7%, the fitting points where the error is 1~2 account for 18.1%, and the fitting points where the error is greater than 2 account for 1.5%. The dynamic change trend of the simulated predicted temperature curve is basically consistent with that of the actual measured temperature curve. It is proved that the building energy consumption simulation and the numerical model of groundwater flow can effectively analyze the rationality of the compound well structure of the groundwater ground source heat pump project and the degree of groundwater heat penetration. [ABSTRACT FROM AUTHOR]

In the face of climate change and constantly progressing urbanization processes, so-called heat islands are observed with growing frequency. These phenomena are mainly characteristic of large cities, where increased air and land surface temperatures form an atmospheric (AUHI) or surface (SUHI) urban heat island (UHI). Moreover, UHIs have also been recognized in the underground environments of many cities worldwide, including groundwater (GUHI). However, this phenomenon is not yet as thoroughly studied as AUHI and SUHI. To recognize and characterize the thermal conditions beneath the city of Wrocław (SW, Poland), we analyze the groundwater temperature (GWT) of the first aquifer, measured in 64 wells in 2004–2005. The study aimed to identify groundwater urban heat islands (GUHI) in Wrocław. Therefore, we used a novel approach to gather data and analyze them in predefined seasonal periods. Meteorological data and satellite imagery from the same period allowed us to link GWT anomalies to the typical conditions that favor UHI formation. GWT anomaly related to the GUHI was identified in the central, urbanized part of Wrocław. Moreover, we found that the GUHI phenomenon occurs only seasonally during the winter, which is related to the city's climate zone and anthropogenic heat sources. Comparing our results with previous works from other cities showed untypical behavior of the observed anomalies. In contrast to AUHI and SUHI temperatures, the GWT anomalies detected in Wrocław are characterized by seasonal transitions from a heat island in winter to a cold lake in summer. Such a transitional character of GUHI is described for the first time. [ABSTRACT FROM AUTHOR]

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The accurate assessment of groundwater levels is critical to water resource management. With global warming and climate change, its significance has become increasingly evident, particularly in arid and semi-arid areas. This study compares new extreme learning machines (ELM) methods tuned with metaheuristic algorithms such as particle swarm optimization, grey wolf optimization, the whale optimization algorithm (WOA), Harris Hawks optimizer (HHO), and the jellyfish search optimizer (JFO) in groundwater level estimation. Daily precipitation and temperature datasets acquired from two stations in northern Bangladesh were used as inputs to the models, which were evaluated based on different quantitative statistics and assessed based on RMSE, MAE, R2, and some new graphical inspection methods. The outcomes of the applications revealed that the efficiency of ELM models was considerably improved by using metaheuristic algorithms. The ELM-JSO improved the RMSE of the standalone ELM model by 13% for the optimal precipitation, temperature, and groundwater level inputs in the testing stage. Among the implemented methods, the ELM-JFO performed the best in estimating the daily groundwater level, and the ELM-WOA and ELM-HHO, respectively, followed it. Viability of a new extreme machine learning (ELM) method tuned with Jellyfish search optimizer (JFO) is investigated in groundwater level estimation. The ELM-JFO is compared with hybrid ELM-PSO, ELM-WOA and ELM-HHO models using daily precipitation and temperature data acquired from two stations of Bangladesh. The ELM-JSO improves the root mean square error of the standalone ELM model by 13% for the optimal precipitation, temperature and groundwater level inputs. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate subaerial taliks' geology, configuration, ground temperature and groundwater level in the continuous permafrost environment of Central Yakutia (Eastern Siberia). The study included geophysical surveys, borehole drilling and measurements of ground temperature and groundwater level variation in a talik aquifer in the Shestakovka research watershed. The talik occupies a gentle, sandy slope covered by a sparse pine forest. Its thickness varies from 3 to 17 m. The talik has several water-conducting branches along its slope. The seasonal thaw layer outside the talik and the talik itself form a single aquifer at the end of the summer. Water-saturated deposits in the talik have a temperature of about 0 °C throughout the year and do not freeze because of the constant filtration of water through the pores and convective heat transfer. Although the groundwater level is relatively close to the land surface, at a depth of just 1–3 m, it has very weak response to snowmelt and precipitation events. The maximum groundwater level occurs in February under cryogenic pressure due to deep seasonal ground freezing above the talik aquifer. Complicated relations between the landscape and the groundwater in the given geological conditions lead to the long-term existence of talik aquifers in the continuous permafrost environment. [ABSTRACT FROM AUTHOR]

In inland settings, groundwater discharge thermally modulates receiving surface water bodies and provides localized thermal refuges; however, the thermal influence of intertidal springs on coastal waters and their thermal sensitivity to climate change are not well studied. We addressed this knowledge gap with a field- and model-based study of a threatened coastal lagoon ecosystem in southeastern Canada. We paired analyses of drone-based thermal imagery with in situ thermal and hydrologic monitoring to estimate discharge to the lagoon from intertidal springs and groundwater-dominated streams in summer 2020. Results, which were generally supported by independent radon-based groundwater discharge estimates, revealed that combined summertime spring inflows (0.047 m 3 s -1) were comparable to combined stream inflows (0.050 m 3 s -1). Net advection values for the streams and springs were also comparable to each other but were 2 orders of magnitude less than the downwelling shortwave radiation across the lagoon. Although lagoon-scale thermal effects of groundwater inflows were small compared to atmospheric forcing, spring discharge dominated heat transfer at a local scale, creating pronounced cold-water plumes along the shoreline. A numerical model was used to interpret measured groundwater temperature data and investigate seasonal and multi-decadal groundwater temperature patterns. Modelled seasonal temperatures were used to relate measured spring temperatures to their respective aquifer source depths, while multi-decadal simulations forced by historic and projected climate data were used to assess long-term groundwater warming. Based on the 2020–2100 climate scenarios (for which 5-year-averaged air temperature increased up to 4.32 ∘), modelled 5-year-averaged subsurface temperatures increased 0.08–2.23 ∘ in shallow groundwater (4.2 m depth) and 0.32–1.42 ∘ in the deeper portion of the aquifer (13.9 m), indicating the depth dependency of warming. This study presents the first analysis of the thermal sensitivity of groundwater-dependent coastal ecosystems to climate change and indicates that coastal ecosystem management should consider potential impacts of groundwater warming. [ABSTRACT FROM AUTHOR]

Rising temperatures and diminishing groundwater availability due to the current climate crisis are predicted to expose cave faunas in eastern North America to unprecedented environmental conditions that could prove detrimental to their unique ecosystems. Organisms that inhabit relatively stable environments like caves are known to develop narrow physiological tolerances. Cave habitats with their organisms are simple ecosystems whose homogeneity offers an ideal system for testing the ability of a highly specialized fauna to tolerate abiotic changes. We tested the capability of a cave-specialized beetle in the eastern United States, Darlingtonea kentuckensis Valentine, to withstand future climatic shifts in its environment. We exposed individuals to a range of relative humidities and temperatures for 10 days. The data strongly suggest that there is a temperature threshold for the survival of D. kentuckensis, but it is a higher thermal tolerance than would be expected in an environment that has not fluctuated in recent evolutionary time and suggests remnant physiological characteristics of ancestral epigean carabids. Decreasing the relative humidity in the environment resulted in a much more dramatic decline in survival, indicating highly evolved specialization for constant high-humidity environments. The narrow humidity threshold in which troglobionts can survive may be a much more apparent limiting factor than temperature in adapting to climatic shifts within a cave environment. [ABSTRACT FROM AUTHOR]

With the disturbance of human factors, the groundwater resources in the source region of the Yellow River have gradually depleted and the water quality has become worse, which has seriously affected the development of high-altitude areas. The groundwater quality of the source region of the Yellow River from 2016 to 2020 was evaluated using single-component and comprehensive evaluation methods, following by a prediction of the groundwater quality from 2021 to 2100 based on the RCPS (RCP 2.6, RCP 4.5, and RCP 8.5) scenarios coupled with the SWAT hydrological model under the CMIP5 global climate model. The results indicated that the groundwater temperature had an increasing trend, pH showed an obvious decreasing trend, and total hardness (Th), sulfate, and ammonia nitrogen (NH4+-N) contents exhibited no obvious increasing or decreasing trend in the source region of the Yellow River during 2016–2020. The increase rate of total nitrogen (TN) and total phosphorus (TP) in the future climate scenario followed the order of RCP 8.5 > RCP 4.5 > RCP 2.6, and the groundwater contents of TN and TP in the source region of the Yellow River gradually increased. This result is of great significance, as it can help clarify the current situation of groundwater in high-altitude and cold regions, showing the influence of groundwater on global climate change. It provides a reference for the development and utilization planning of groundwater resources in the source region of the Yellow River in the future. [ABSTRACT FROM AUTHOR]

Microbial reductive dechlorination is a key process in aquifers contaminated with chlorinated ethenes and results in a net mass reduction of organic pollutants. Biodegradation rates in the subsurface are temperature-dependent and may be enhanced by increased groundwater temperatures. This study explores the potential of combining the temperature increase from low-temperature Aquifer Thermal Energy Storage with In Situ Bioremediation (ATES-ISB). The effects of highly dynamic groundwater flow and heat transport on microbial degradation rates were examined in a contaminated aquifer based on a pilot-scale experiment and a comprehensive process-based modeling analysis. The low-temperature ATES-ISB pilot test was carried out in Birkerød (Denmark), in an aquifer contaminated with trichloroethene by implementing a groundwater flow dipole, injecting heated groundwater, biostimulating the system with lactate and bioaugmenting it with a Dehalococcoides containing culture. Solute concentrations were monitored in four observation wells over the course of the test and a non-isothermal reactive transport model, solved in a two-dimensional heterogeneous domain, was developed to quantitatively interpret the experimental observations. The process-based numerical model also allowed evaluating the evolution of chlorinated ethenes concentrations considering different hydraulic, thermal, and operational scenarios. The results demonstrate the beneficial combination of ATES with in situ contaminant bioremediation, showing enhancement of contaminant mass reduction and more complete reductive dechlorination. The developed process-based model can be instrumental for the design and parameterization of pilot and full scale low-temperature ATES-ISB remediation in shallow aquifer systems. • Pilot test of ATES combined with in situ bioremediation in a contaminated aquifer • Numerical model coupling non-isothermal flow, heat and reactive transport • Simulation of pilot test operations and model-based analysis of observations • Temperature-dependent flow, transport and degradation rates of chlorinated ethenes • Scenario simulations to assess the effects of different remediation approaches [ABSTRACT FROM AUTHOR]

The effect of water temperature variation in a river channel on groundwater temperature in the confined aquifer it cuts can be generalized to a one-dimensional thermal convection-conduction problem in which the boundary water temperature rises instantaneously and then remains constant. The basic equation of thermal transport for such a problem is the viscous Burgers equation, which is difficult to solve analytically. To solve this problem, the Cole–Hopf transform was used to convert the second-order nonlinear thermal convection-conduction equation into a heat conduction equation with exponential function-type boundary conditions. Considering the difficulty of calculating the inverse of the image function of the boundary function, the characteristics and properties of the Laplace transform were used to derive the theoretical solution of the model without relying on the transformation of the boundary function, and the analytical solution was obtained by substituting the boundary condition into the theoretical solution. The analytical solution was used to analyze the temperature response laws of aquifers to parameter variation. Subsequently, a 40-day numerical simulation was conducted to analyze the boundary influence range and the results from the analytical method were compared to those from the numerical method. The study shows that: (1) the greater the distance from the river canal and the lower the aquifer flow velocity, the slower the aquifer temperature changes; (2) the influence range of the river canal boundary increases from 18.19 m to 23.19 m at the end of simulation period as the groundwater seepage velocity v increases from 0.08 m/d to 0.12 m/d; (3) the relative errors of the analytical and numerical methods are mostly less than 5%, confirming the rationality of the analytical solution. [ABSTRACT FROM AUTHOR]

This study aimed at the analysis and modelling of the groundwater temperature at the water table in different regions of Slovakia. In the first part, the analysis of the long-term trends of air and soil/ground temperature to a depth of 10 m is presented. The average annual soil/groundwater temperatures at different depths were the same but lower than the annual average air temperature by about 0.8 °C. The long-term trend analysis of the air temperature and soil temperature at a depth of up to 10 m in Slovakia showed that the air and soil/ground water temperature have risen by 0.6 and 0.5 °C, respectively, per decade over the past 30 years. The second part of the study aimed at modelling the daily groundwater temperatures at depths of 0.6–15 m below the surface. The simple groundwater temperature model was constructed based on a one-dimensional differential Fourier heat conduction equation. The given model can be used to estimate future groundwater temperature trends using regional air temperature projections calculated for different greenhouse gas emission scenarios. [ABSTRACT FROM AUTHOR]

An alluvial fan is a good area to install open-loop geothermal heat pump (GHP) systems due to shallower aquifers, faster groundwater flow, and fewer land subsidence risks. The natural temperature change in groundwater occurs in alluvial fans due to the recharge of river water and faster groundwater flow, and the thermal impact of the open-loop system has not been studied well in such areas. The purpose of this research is to understand the thermal impact of open-loop GHP systems on an alluvial fan. A regional 3D model of groundwater flow with heat transport was created to determine the distribution of flow velocity and temperature of groundwater. After that, two local models with different groundwater velocities were constructed to demonstrate the thermal impact of an open-loop GHP system using one extraction and one injection well. The results indicated that the local model with faster groundwater flow had a smaller thermal impact. The natural temperature change in groundwater causes groundwater temperature to be lower in the summer and higher in winter during the operation in the local model, with faster groundwater flow. [ABSTRACT FROM AUTHOR]

Protecting endangered plant species is crucial to maintaining biodiversity. Currently, there is a rapid decline in the populations of many moisture-loving plant species throughout Poland. These include the entire genus Drosera, so this paper attempts to determine the main reasons for the decline of Drosera intermedia and Drosera anglica in the Łęczna-Włodawa Lake District. For this purpose, the habitat conditions, climatic factors of the sites, as well as the vegetation of their current and historically abundant occurrence were compared, and it was shown that an important reason for the receding of sundews may be changes associated with rising temperatures in the study area. In the case of Drosera anglica, a clear preference was observed for colonising sites associated with the shoreline of lakes, more hydrated and almost devoid of companion plants. For Droseraintermedia, on the other hand, it was revealed that it acclimatises to mid-forest peatlands, rich in magnesium, nitrogen, phosphorus, and manganese, with moderate carbon content, medium levels of groundwater and air temperature, and low concentrations of organic matter. In addition, it was noted that sundew sites are characterised by lower diversity indices but a greater number of rare and protected species and significantly lower concentrations of iron and potassium. [ABSTRACT FROM AUTHOR]