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[Display omitted] • Fe2+ in groundwater serves as a sustained catalyst to drive the removal of NH 4 +-N. • High selectivity of NH 4 +-N conversion to N 2 by PMS- Fe 3 O 4 /Cl– system. • Ammonia removed by Cl• − mediated AOPs even under microtherm conditions. • Reliability assessment of NH 4 +-N in-situ removal by PMS-Fe 3 O 4 /Cl– system. The conventional ammonia in-situ treatment technology fails to achieve complete NH 4 +-N degradation, while the high concentration of native iron in groundwater further complicates its removal process, potentially leading to adverse environmental consequences. This study investigates the introduction of peroxymonosulfate (PMS) into groundwater containing high concentrations Fe2+ (Fe 3 O 4 as a ferrous source), which can act as persistent catalysts, and Cl-, causing the degradation of ammonia through chlorine free radical-based advanced oxidation processes (PMS- Fe 3 O 4 /Cl-), and evaluates the advantages and limitations of employing the PMS- Fe 3 O 4 /Cl- system for ammonia treatment. The rapid reaction between SO 4 •- and Cl- resulted in the formation of Cl• as primary products. Cl• initiates a cascade of subsequent reactions with pH-dependent secondary active products. Under optimal conditions, the ammonia removal efficiency reached 97.44 % using the PMS- Fe 3 O 4 /Cl- system within 120 min of operation, which can be attributed to the selective oxidation of ammonia by chlorine reactive species. And this finding was substantiated by observations from experiments involving free radical quenching and EPR spectra coupled with DMPO. The HCO 3 – and humic acid (HA) in water can significantly affect the removal of ammonia, owing to their capability of quenching SO 4 •- and Cl•. Meanwhile, the levels of generated toxic chlorates in our system remain within acceptable limits. The PMS- Fe 3 O 4 /Cl- system exhibited outstanding transport capacity and stability in simulated columns, demonstrating excellent ammonia oxidation efficiency in natural groundwater, thereby confirming its promising practical potential. All experiments were executed at a temperature of 12 ℃, thereby verifying the remarkable efficacy of the PMS- Fe 3 O 4 /Cl- system in removing ammonia even under microtherm conditions. [ABSTRACT FROM AUTHOR]

The production of freshwater represents a prominent global challenge nowadays. One eco-friendly technology to provide clean water even in an adverse environment, with extreme temperatures and scarce groundwater resources is solar-driven water evaporation or solar-to-steam generation. Besides, freshwater can be also extracted from polluted soil or water, purifying the water in the process at the same time. The champion solar-driven water evaporation efficiency is achieved at over 100%. The advancements in photothermal evaporation predominantly prioritize material modification and interfacial heating, with a significant emphasis on optimizing vapor generation efficiency, often neglecting the practical aspect of water collection. By using the right materials, the system can be cost-effective and have a low environmental impact. In this progress report, the latest advancements in natural materials, carbonization of natural materials, hybrid natural materials, and nature-inspired materials are presented. We will delve into their effectiveness in evaporation and their energy efficiency. The review provides suggestions about the compatibility of natural materials for this application and reports on insights into the advancements already accomplished, as well as the remaining opportunities for enhancing the performance of these cost-effective, environmentally friendly, high-performance systems. [Display omitted] • Recent developments of nature-inspired design for solar vapor have been reviewed. • The effectiveness of evaporation and its energy efficiency are discussed. • The suggestions about the compatibility of natural materials are highlighted. • This work reports on insights into the advancements already accomplished. • The crucial challenges in this field are emphasized. [ABSTRACT FROM AUTHOR]

[Display omitted] • Models consider groundwater (GW) inflow, conduction, shading, and other heat fluxes. • Equilibrium temperature deficit concept is used as scenario comparative benchmark. • GW inflow and riparian shading most strongly drive changes in temperature signals. • These scenarios support process-based interpretation of paired air–water metrics. • GW source depth and inflow magnitude affect climate change thermal resilience. Headwater stream temperature often exhibits spatial variation at the kilometer-scale, but the relative importance of the underlying hydrogeological processes and riverine perturbations remains poorly understood. In this study, we investigated the relative importance of groundwater (GW) and other processes on downstream annual stream temperature signal characteristics using deterministic heat budget model (HFLUX) scenarios within an idealized stream reach representative of mountainous forested conditions. We summarized annual stream thermal regimes from the relationship of paired sinusoidal air and water temperature signals (amplitude ratio, phase lag, and mean ratio). Results showed that downstream changes in annual temperature depended on the thermal gradient between water and the hypothetical equilibrium temperature (where all heat fluxes sum to zero). GW inflow, riparian shading, and the boundary input signal were the most significant factors affecting downstream annual water temperature signals, while flow volume and channel dimensions impacted how quickly annual temperature signals changed. Effects of GW were dominated by advective rather than conductive heat exchange processes, but conduction played a larger role when GW input was more spatially diffuse. Our results indicated several mechanisms by which local processes may affect stream thermal resilience to disturbances and can help guide management of wildfire and climate change. [ABSTRACT FROM AUTHOR]

Climate warming has significantly changed the hydrological cycle in cold regions, especially in areas with permafrost or seasonal frost. Groundwater flow and its interactions with surface water are essential components of the hydrological process. However, few studies or modeling works have been based on long-term field observations of groundwater level, temperature, hydrogeochemistry, or isotopic tracers from boreholes due to obstacles such as remote locations, limited infrastructure, and harsh work conditions. In the Hulugou catchment, an alpine catchment in the headwater region of the Heihe River on the northern Qinghai–Tibet Plateau (QTP), we drilled four sets of depth-specific wells and monitored the groundwater levels and temperatures at different depths. Surface water (including river water, glacier meltwater, and snow meltwater), precipitation, groundwater from boreholes, spring water, and soil water were sampled to measure the abundances of major and minor elements, dissolved organic carbon (DOC), and stable and radioactive isotopes at 64 sites. This study provides a dataset of these groundwater parameters spanning 6 consecutive years of monitoring/measurements. These data can be used to investigate groundwater flow processes and groundwater–surface water interactions on the QTP under global climate change. The dataset provided in this paper can be obtained at 10.5281/zenodo.6296057 (Ma et al., 2021b) and will be subject to further updates. [ABSTRACT FROM AUTHOR]

Accurate monitoring and controlling of the temperature in the combustion chamber can raise the burner efficiency, combustion intensity, fuel consumption and reduce pollutant emission. However, except combustion is accurately monitored and controlled, high concentration of pollutant gases and products like carbon monoxide (CO) and soot can form in the combustion chamber. This paper compares the combustion thermal profiles in a liquid fuel swirl burner using developed straight edge and curve edge blade swirlers at (20, 30, 40, 50 and 60)° for 6, 8, 10 and 12 number of blades in order to optimize the temperature of the burner. Measurements were made in straight and curve blades liquid fuel swirl burner in order to study and compare the thermal characteristics of the straight and curve edge blades in optimizing the combustion dynamics. Similarly, measurements were made for burner without swirl generator and the combustion temperature assessed. Thermal profile was measured in the direction of flow via the six axial ports at distance ((d) = 150, 350, 550, 750, 950 and 1150 mm) from the burner exit using Chromium-Zinc thermocouple. Results showed that the wavelength and oscillation of temperature decay in the same type of blade followed the same trend and the peak of combustion intensity is nearer the nozzle for curve edge blades than the straight edge blade. Six (6) blades performed best with the highest temperature in all the ports, while 12 blades gave the least performance. Findings further show that curve edge blade swirlers gave better performance than straight edge blade swirlers with highest temperature of (1065 and 1015) °C, respectively. Hence, it is recommended especially where high temperature and stability application is desirable. [ABSTRACT FROM AUTHOR]

This paper discusses the application of Fresnel Lens Concentrator for Solar Water Heater which is a case study in Indonesia. The purpose of this study was to find an empirical equation of the relationship between Direct Normal Irradiance (Ib) and focal point temperature (Tf). The research location is Latitude: 7.9553 °S and Longitude: 112.6145 °E. The SM-206 solar power meteris used. The Fresnel lenses are made of PMMA material. Its specifications are: diameter = 1000 mm; weight = 2 kg; thickness = 2 mm; groove pitch = 0.5 mm and focal length = 880 mm. The main experimental setup consists of a PMMA Fresnel lens and a receiver. The conical cavity receiver has specifications; geometric concentration ratio, CRg = 8, and V = 2 Liters. Temperature measurement is done using a temperature data acquisition system. The K-type thermocouple is used to measure: 1) ambienttemperature (Ta); 2) the focal point temperature (Tf); 3) receiverwall temperature (Tr); 4) watertemperature (Tw). The experiment obtained the results of the empirical equation for the relationship between Direct Normal Irradiance (Ib) and focal point temperature (Tf). The increase in solar radiation produces a focus temperature, exponentially. At DNI 858 W/m2 it can produce a focal temperature of up to 1064 °C. The efficiency of the receiving cavity of the thermal cone which contains 2 litres of water and CRg = 8 under conditions of relatively Direct Normal Irradiance (Ib = 675 W/m2) is about 10.61 %. Furthermore, the energy that can be generated in heating water is 0.17-0.32 MJ, in 100 minutes. Heat convection and radiation loss can be reduced by adding an insulating layer to the walls and coating the surface with black. [ABSTRACT FROM AUTHOR]

Geothermal wells with depths of 4.3 and 4.1 km were drilled into an enhanced geothermal system (EGS) in Pohang, Republic of Korea. After five times of hydraulic fracturing, the groundwater level of the geothermal wells decreased after a Mw 5.5 earthquake in Pohang. The objective of this study was to monitor the groundwater level and temperature and determine the hydrogeological and hydrochemistry of two geothermal wells (PX-1 and PX-2) and one monitoring well (EXP-1) at the EGS site. The hydrochemical data of the EGS wells was also compared with the groundwater characteristics of eight wells at the National Groundwater Monitoring Station (NGMS). First, groundwater samples were collected from a depth of approximately 700 m, and an automatic water level recorder was used to monitor changes in the groundwater level and temperature for two years at the EGS site. Second, groundwater level and temperature data in the NGMS wells were collected from the National Groundwater Information Center's website and annual report on groundwater monitoring for comparisons with the EGS site. The results showed that the rate of groundwater increase was in the order PX-2, PX-1, and EXP-1, and the temperature decrease was the fastest in PX-1 and similar between PX-2 and EXP-1. The eight wells in the NGMS showed only temporary changes. The groundwater in the EGS is the Na-Cl type, but that in the NGMS is a mixture of the Ca-HCO3 and Na-HCO3 type. The EGS site has not yet recovered from the earthquake. [ABSTRACT FROM AUTHOR]

The Zhuoshui River alluvial fan is one of the most important groundwater and agricultural areas in Taiwan. Abundant groundwater resources are the main source of domestic water supply and irrigation water. However, groundwater recharge and groundwater quality have been greatly affected under extreme climate and hydrological conditions. Hence, the quality of groundwater has been a topic of concern to the public. In this study, groundwater level and groundwater quality data of the Zhuoshui River alluvial fan from 2008 to 2020 were used to divide the wet and dry season groups according to the sampling dates. An independent samples t-test was used to evaluate the differences in the mean groundwater level and the mean concentration between the wet and dry seasons. The test results show that there was no statistically significant difference in the mean groundwater level between the wet and dry seasons. This may result from the time lag effects of groundwater recharge. Except for groundwater temperature, bicarbonate, and total organic carbon (TOC), there were no significant differences among the mean concentrations of other groundwater quality parameters in Aquifer 1 and Aquifer 2 between the wet and dry seasons. In terms of the alluvial fan location, although the soil texture, land utilization, cropping systems, and hydrogeology of the proximal, mid-, and distal fan may affect groundwater quality variations, it seems that only Aquifer 1 is affected by surface water infiltration, resulting in significant differences in mean groundwater temperature, mean concentrations of major ions, and nitrate between the wet and dry seasons, whereas Aquifer 2 is less affected. At the same time, owing to the geological conditions and intensive cultivation in the Zhuoshui River alluvial fan, nitrate and arsenic could represent a high risk to the public's health if groundwater is used as a source for domestic water supply or irrigation water in the distal fan area, whether in the wet season or dry season. Meanwhile, due to global climate change and uneven droughts and floods, the hydrological conditions of the so-called "wet season" and "dry season" are obviously different from those in the past. Compared with precipitation, groundwater level may be a better indicator for understanding variations in groundwater quality. [ABSTRACT FROM AUTHOR]

The Independence Basin is located in a semi-arid region of Mexico, delimited predominantly by volcanic mountains. Around 30 m3/s of water are extracted from regional aquifers mainly for agro-export activities, causing declines in the water table of up to 10 m/a, increased temperature and dissolved elements that are harmful to health and the environment. Regional groundwater coupled flow and heat transport under current conditions were studied on a basin-wide scale (7000 km2) using a three-dimensional finite-element model under steady-state conditions to provide support for water management decisions and transient modeling. Isothermal, forced and free thermal convection under existing hydrological conditions prior to pumping are analyzed. The results show that the interaction of topography-driven groundwater flow and buoyancy-driven free thermal convection are consistent with historical hydrological records, the characteristics of the water table, and thermal anomalies observed in the basin. The simulated groundwater recharge is near 7 ± 0.25 m3/s, a balance broken since the 1980s by extensive pumping. The results show the importance of considering the groundwater temperature, its transient response in the evolution of groundwater extraction, and the upward migration of a thermal front through the fractured aquifer that has increased risks for health and sustainability. [ABSTRACT FROM AUTHOR]

Groundwaters recovered from the Salar de Punta Negra and Monturaqui basins in the Atacama Desert of northern Chile exhibit distinctly different isotopic, major, trace, and porphyry copper elemental compositions related to contrasting morphostructural, geochemical, and hydrodynamic settings. Comparison of these distinct groundwater signatures with groundwaters from known porphyry copper deposits (Salar de Hamburgo and Spence Deposit), can be used to determine if either basin might be prospective for porphyry copper mineralization. Groundwaters within the Punta Negra Basin exhibit geochemical characteristics consistent with other closed basin settings throughout the arid Andes. Elemental and isotopic compositions within the Punta Negra Basin reflect closed basin evaporitic processes consistent with the hyperarid, volcanic setting of the central Andes. Pathfinder metals and isotopic compositions are not consistent with porphyry copper type mineralization as described for groundwaters within the Salar de Hamburgo Basin, and the Spence Deposit. Within the Monturaqui Basin the geochemical composition of groundwaters are characteristic of diffuse hydrothermal activity. Sulfur isotopic composition within the waters of the northern Monturaqui Basin exhibit δ 34SCDT isotopic signatures that fall within the range for sulfide mineralization as reported for groundwaters in and around the Spence Deposit and the Salar de Hamburgo. However, porphyry copper related elements within the Monturaqui Basin are impoverished relative to groundwaters of the Spence and Escondida Deposit. Such impoverishment in porphyry related elements, taken in conjunction with enriched δ 13CPDB compositions, elevated groundwater temperatures, groundwater compositions dominated by HCO3, SO4, and Si, and the proximity of the Monturaqui Basin to the current magmatic arc are consistent with a volcanic hydrothermal origin. In summary, the groundwater geochemistry of the Monturaqui and Punta Negra Basins are not indicative of porphyry copper-type mineralization. Thematic collection: This article is part of the Hydrochemistry related to exploration and environmental issues collection available at: https://www.lyellcollection.org/cc/hydrochemistry-related-to-exploration-and-environmental-issues [ABSTRACT FROM AUTHOR]

Acquitard hydraulic properties are notoriously difficult to assess, yet accurate acquitard hydraulic conductivity estimates are critical to quantify recharge and discharge to and from semi‐confined aquifer systems via hydraulic head gradients. Such flux quantification is required to evaluate the risks of aquifer exploitation by groundwater abstraction and aquifer vulnerability to surface contamination. In this study, we consider a regionally important acquitard and compare existing hydraulic conductivity estimates obtained through traditional methods to those inferred from long‐term hydraulic head monitoring and thermally derived vertical groundwater fluxes (0.04–0.25 m/y). We estimate the fluxes using numerical modeling to analyze the propagation of decadal climate signals into temperature‐depth profiles and fitting the simulated and observed inflection point depths (location of minimum temperature). Results suggest that climate‐disturbed temperature‐depth profiles paired with multi‐level head data can yield accurate vertical fluxes and acquitard hydraulic conductivities. This approach for characterizing groundwater systems and quantifying flows to and from sedimentary aquifers is more efficient but yields results that are comparable to conventional methods. Plain Language Summary: In sedimentary aquifer systems the in and outflow toward deeper groundwater is strongly controlled by the hydraulic conductivity of clay and silt layers and the quantification of these fluxes is crucial for the sustainable management of water resources. However, the low permeability of such units is difficult to establish from in‐situ or laboratory measurements. Alternatively, environmental isotopes have been widely used to estimate travel times of groundwater across such units. In this paper we present a novel technique to estimate vertical groundwater flow rates, based upon heat as a tracer, that opportunistically exploits the impacts of accelerated surface warming on subsurface thermal regimes. We show how a parsimonious analysis of temperature‐depth profiles that are disturbed by surface warming, in combination with hydraulic head data, lead to accurate and reliable estimates of aquitard hydraulic conductivity. This approach for characterizing groundwater systems and quantifying flows to and from sedimentary aquifers is more efficient and may be more accurate than conventional methods. Key Points: Temperature‐depth profiles disturbed by climate change can be analyzed to quantify groundwater fluxes across aquitardsTemperature‐derived groundwater fluxes are analyzed in conjunction with hydraulic head data to estimate aquitard hydraulic conductivityEstimates of aquitard hydraulic conductivity agree with independent assessments based upon conventional methods [ABSTRACT FROM AUTHOR]

Reinjection of excess water from the power production process in the Nesjavellir geothermal field has increased the temperature of shallow groundwaters, posing a risk to cold water wells used for the power plant as well as the ecosystem in Lake Thingvellir. Here, we present a numerical model of fluid flow and heat transport in the shallow reinjection zone to elucidate the flow path of reinjected liquid and the impact of reinjection on the temperature of groundwaters. The permeability structure of the model is based on a 3D geological model of the area. The numerical simulation is calibrated against underground water temperature data measured between 1998 and 2018 and data from a tracer test performed in 2018–2019. The model reproduces the overall temperature field and shows how a high-permeability lava flow together with rift-parallel normal faults act as permeable channels controlling fluid transport. If injection continues, the temperature along the lava flow increases considerably and spreads vertically to much deeper levels, generating a narrow warm zone along the main fault. If shallow injection ceases, temperature drops rapidly at the surface, but decreases slowly around the reinjection zone over 20 years. The numerical model in this study allowed a better characterization of the fracture–matrix interface and the porosity of post-glacial lava flows, contributing to sustainable management of the geothermal resource and the surrounding environment. [ABSTRACT FROM AUTHOR]

Groundwater temperature (GWT) is usually measured using screened monitoring wells (MWs). The aim of this study was to investigate whether MWs are suitable for monitoring the effects of large-scale geothermal collector systems (LSCs) on GWT, focusing on possible vertical flows within the MWs due to both natural and forced convection. Comparative temperature depth profiles were therefore recorded over a period of nine months in both shallow MWs and in small-diameter, non-screened temperature monitoring stations (TMSs), each of which was installed in a single borehole. Particularly high temperature deviations were measured in MWs in the upper part of the water column where the GWT reached up to 1.8 K warmer than in the surrounding subsurface. These deviations correlate unambiguously with the prevailing positive thermal gradients and are caused by thermal convection. Where forced convection occurred, the GWT was measured to be up to 0.8 K colder. Potential temperature deviations must be considered when monitoring very shallow GWT as thermal gradients can be particularly high in these zones. For monitoring concepts of LSCs, a combination of MW and TMS is proposed for GWT measurements decoupled by the effects of convection and in order to enable further investigations such as pumping tests. [ABSTRACT FROM AUTHOR]

Urban aquifers are a valuable resource of freshwater for cities, however, their quality is degraded due to the presence of organic contaminants of emerging concern (CECs). The effects of organic CECs are largely unknown, but there is evidence that they pose a risk for human health, soil, plants and animals. Organic CECs are naturally degraded in aquifers and their degradation rates depend on the physico-chemical properties, i.e., redox conditions and groundwater temperature. Some anthropogenic activities, like low-enthalpy geothermal energy (LEGE), may modify subsurface physico-chemical conditions altering the behaviour of organic CECs. LEGE is a renewable and carbon-free energy that allows obtaining cooling and heating energy. The utilization of LEGE is currently growing and it is expected that in a near future the density of LEGE systems will increase. LEGE modifies the groundwater temperature and in some situations the redox state (i.e., if the dissolved oxygen increases when groundwater is returned to the aquifer as a result of a poorly design), thus, it is of paramount importance to determine the impact of LEGE related activities on the behaviour of organic CECs. The behaviour of organic CECs under the influence of LEGE is investigated by means of thermo-hydro-chemical numerical modelling. Simulation output shows that LEGE activities have the potential to modify the degradation rates of organic CECs, and thus, their concentrations in aquifers. In the simulated scenario, the concentration of the chosen CEC decreases by the 77 % at the downgradient boundary of the model. The results of this study have significant implications for predicting the behaviour of organic CECs in urban aquifers and suggest specific changes in the design of LEGE facilities aiming to improve the quality of urban groundwater by boosting in-situ attenuation mechanisms. [ABSTRACT FROM AUTHOR]

Rock slope failures often result from progressive rock mass damage which accumulates over long timescales. In deglaciating environments, rock slopes are affected by stress perturbations driven by mechanical unloading due to ice downwasting and concurrent changes in thermal and hydraulic boundary conditions. Since in‐situ data are rare, the different processes and their relative contribution to slope damage remain poorly understood. Here, we analyze borehole monitoring data from a rock slope adjacent to the retreating Great Aletsch Glacier (Switzerland) and compare it to englacial water levels, climate data, and decreasing ice levels. Rock slope pore pressures show a seasonal signal controlled by infiltration events as well as effects from the connectivity to the englacial hydrological system. We find that reversible and irreversible strains are driven by: (a) hydromechanical effects caused by englacial pressure fluctuations and infiltration events, (b) stress transfer related to changing mechanical glacial loads from short‐term englacial water level fluctuations and longer term ice downwasting, and (c) thermomechanical effects from annual temperature cycles penetrating the shallow subsurface, which primarily result in reversible deformation. We relate most observed irreversible strain (damage) to mechanical unloading from ice downwasting. Damage is strongest directly at the ice margin and moves through the slope at the pace of glacial retreat and advance. Locations with many retreat/advance cycles are very sensitive to landslide formation. The current climate warming impacts very sensitive valley sectors, which is confirmed by landslide distributions and activity in the study area. Plain Language Summary: The formation of rock slope instabilities is a long‐term process related to continuous rock mass weakening. For rock slopes in glaciated valleys, increased rates of rock mass damage are assumed to occur during ice retreat due to a reduction of the glacier weight and concurrent changes in rock temperatures and slope groundwater pressures. However, because direct field measurements are missing, governing processes and their relative importance are still poorly understood. Here, we analyze borehole monitoring data and compare it to englacial water levels, climate data, and decreasing ice levels. We find that the glacial hydrology influences the dynamics of the groundwater pressures in the adjacent rock slope at various timescales. We record micrometer‐scale reversible (elastic) deformation and irreversible rock mass damage and identify the involved drivers. Several processes contribute to progressive rock mass weakening at different timescales and magnitudes, but most damage is related to mechanical unloading from ice downwasting and is strongest directly at the ice margin. Locations with many retreat/advance cycles are sensitive to increased damage accumulation and landslide formation. The current climate warming impacts very sensitive valley sectors, which is confirmed by landslide distributions and activity in the study area. Key Points: We monitored subsurface pore pressures and micrometer scale strain in a rock slope during strong glacial retreat caused by climate warmingWe identified thermo‐hydro‐mechanical drivers for reversible deformation and irreversible rock mass damage acting at various timescalesSlope damage intensity can be related to landslide spatial and temporal distribution [ABSTRACT FROM AUTHOR]

Assessing water travel times in hyporheic and adjacent alluvial sediments is important to quantify exchange rates, biogeochemical turnover, and pollution dynamics across groundwater‐surface water interfaces and in floodplain aquifers. Heat and 222Rn are useful natural tracers for this purpose. While heat transport is commonly simulated via the convection‐conduction equation, the transport of 222Rn is often simulated assuming purely advective transport and a homogenous distribution of 222Rn production rates across the model domain. In the present study, we explicitly model the production, transport, and radioactive decay of 222Rn after surface water infiltration into an alluvial aquifer with the numerical models MODFLOW‐NWT and MT3D‐USGS. Using field observations, numerical modeling, and laboratory experiments, we show that 222Rn production rates vary substantially in the alluvial aquifer of a lowland river. Distributions of mean river‐to‐groundwater travel time in the alluvial aquifer, estimated via a Bayesian approach, shifted considerably depending on whether 222Rn and time series of groundwater heads and temperature were jointly inverted and whether 222Rn production rates were allowed to vary spatially. With distance to the river, differences between the median river‐to‐groundwater travel time and apparent 222Rn ages increased by factors ranging from 1.4 at 4 m to 11.9 at 59 m, a finding that highlights the need to simulate 222Rn transport explicitly. The joint inversion of 222Rn, groundwater heads, and temperature reduced uncertainty associated with mean travel times, suggesting that the uncertainty introduced by spatially varying 222Rn production rates can at least partly be compensated by using a combination of natural tracers. Plain Language Summary: Rivers and groundwater bodies exchange water back and forth. Knowing the time that water spends traveling from rivers to certain points in groundwater is important for water management, particularly in situations where drinking water is produced via bank filtration: It allows to predict what happens to natural and toxic compounds that come from the river and to assess the quantity of water moving from rivers to aquifers. Here, we present a modeling approach to estimate travel times of groundwater originating from a nearby river. The approach uses the open‐source software packages MODFLOW‐NWT and MT3D‐USGS and a combination of natural tracers, such as the noble gas 222Rn, which is produced in the subsurface with varying rates but decays with a constant rate constant. We demonstrate that by using both 222Rn and other natural tracers, such as heat, we estimate travel times from rivers to points in groundwater with less uncertainty. Key Points: A flexible approach to explicitly model the transport of 222Rn in saturated porous media using MODFLOW‐NWT and MT3D‐USGS is presentedSpatially varying 222Rn production rates, found to vary by a factor of two at relatively small spatial scales (<100 m), are consideredA joint inversion of hydraulic heads, temperature, and 222Rn reduced the high degree of uncertainty in the estimated groundwater travel times [ABSTRACT FROM AUTHOR]

A losing river usually produces riparian groundwater mounds. Knowledge of influences of the mound on riparian hydrological processes is still limited. To fill the gap, we measured the annual regime of riparian groundwater at a cross‐section of a river channel in a semi‐arid valley where the water transfer is running. Results show that the hydrologic processes were totally controlled by the water transfer. The river runoff was dominated by the transferred water. Regulation of the water transfer caused river stage fluctuations that were companied by hydrochemical variations of the river water. The water transfer enhanced infiltration into the riparian zone. Consequently, the river water and the riparian groundwater kept connection during the one‐year observation. The annual recharge and the input of total dissolved solids (TDS) from the river to the riparian zone reached 195.8 m3 and 125.0 kg, respectively. Furthermore, the Pearson's r between the river stage and riparian groundwater level was 0.98 at 2 m, 0.94 at 20 m, and 0.93 at 40 m (α = 0.01) from the riverside, respectively. The curved river produces the convergence of hydraulic gradients, which drives the overlap of groundwater mounds. The overlap is evidenced by anomalies in water level, hydrochemistry, and temperature of the riparian groundwater at the cross‐section. When the river stage and adjacent groundwater level went down, the overlap locally reversed the hydraulic gradient to point to the river hindering the recharge from the river. Hence, the average daily recharge from the river decreased from 1.10 to 0.59 m3. The riparian groundwater discharged into the river after quick declines of the river stage. In total, 39.2 m3 of riparian groundwater discharged into the river accounting for 20% of the annual recharge from the river. The impact of the hydrochemical variation of the river water on the riparian groundwater was also blocked due to the overlap. Also 20% of the TDS input was returned to the river. The overlap reduced the impact of the water transfer on the local environment. [ABSTRACT FROM AUTHOR]

Peatlands are shaped by slow litter decomposition, but threshold decomposition rates that allow peat formation remain unclear. Can agroforestry in the tropics be compatible with paludiculture that allows peat formation? We explored the determinants of litter decomposition in wet agroforests adjacent to tropical peatlands in Central Kalimantan (Indonesia) by litterbag studies (up to 16 weeks) with standing litter sources to estimate rate constants, characterize litter quality (especially lignin (L), polyphenolics (Pp) and nitrogen (N)), and monitor temperature and groundwater levels. In litter transfer experiments we tested for home-field advantage (HFA) effects between land cover types. Mean residence times around 85 weeks at 27 °C were associated with a high (L + Pp)/N ratio. However, in the crossover treatments, mean residence times varied from 30 to 180 weeks and strong HFA effects (up to 80% faster decomposition at "home") were found when litter from other sources was tested in old fruit-based agroforests. HFA indicates a local decomposer community well-adapted to its normal litter diet. Litter residence times of around two years are below the apparent peat formation threshold. Maintaining wet agroforest conditions adjacent to peat domes supports peatland rewetting and restoration but does not contribute to on-site peat formation processes. [ABSTRACT FROM AUTHOR]

Globally, agricultural productivity is adversely impacted due to climatic changes as the temperatures rises and precipitation decreases, and especially in Pakistan, which ultimately enhanced groundwater salinity and harmed water quality in the country. However, the impacts of groundwater salinity and climate change on farmers' revenue have not been fully understood in Pakistan. Therefore, the focus of current research is the assessment of shadow price of water, farmers' revenue, and socioeconomic and environmental indicators affected by variations in groundwater salinity, precipitation, and temperature. The estimation of crop yield sensitivity to groundwater salinity, precipitation, and temperature and their prediction for 2030, 2040, and 2050 time periods was accomplished through the technique of General Maximum Entropy and Response-Yield function. Moreover, the assessment of groundwater quality and climate variable impacts on socioeconomic and environmental indicators was obtained through Target Motad-PMP model. In the end, the most suitable climate change scenario in the study area was established by applying a multi-criteria decision-making method. The results revealed that groundwater salinity and temperature expressed a significantly increasing trend with the Z values of 5.82 and 2.15, respectively. While the precipitation depicted a significantly decreasing trend (Z value = −3.37). The negative impact of climatic changes and groundwater salinity was revealed for revenue risk and shadow prices of water. The most negative impact on income risk and shadow prices is during 2050 horizon with a decrease by 11.4 and 19.4% respectively. The environmental index is the most important with a priority of 43.4% compared to the socio-economic indicators. The sub-index water use is also significant in the study area with a priority of 28.1%. A2 is the most appropriate climate scenario conferring to the TOPSIS ranking method. Therefore, the A2 scenario should be taken into account for the policy of adaptation to the climate change wonder in district Kohat. [ABSTRACT FROM AUTHOR]

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Previous studies have indicated aquifer heterogeneity has an important influence on the removal of Cr(VI) in groundwater, but little attention is paid to the effects of aquifer heterogeneity during the process especially under conditions like actual groundwater temperature and hydraulic gradient in the field. Thus, in this study, in situ remediation of Cr(VI)-contaminated shallow groundwater in a sandbox was conducted, and the influences of the heterogeneous aquifer composed of coarse, medium, and fine sand on Cr(VI) diffusion and removal before and after emulsified vegetable oil (EVO) injection were investigated, under the conditions of 19±0.5 °C and hydraulic gradient 3‰. The results show that Cr(VI) diffused consistently with groundwater from top left to bottom right; Cr(VI) spread faster in the horizontal direction than in vertical direction, and the horizontal diffusion of Cr(VI) in coarse, medium, and fine sand was 0.054 m/day, 0.036 m/day, and 0.018 m/day, respectively; a high performance of EVO toward Cr(VI) removal by over 95% was mainly because different concentrations of microorganisms migrated among heterogeneous aquifers vertically and horizontally; compared with coarse and medium sand, fine sand, with a better adsorption capacity and a lower permeability, retained relatively more microorganisms, providing favorable conditions during the remediation; a stable and unified effective removal zone, similar to the shape of Ʃ (approximately 1357.87 cm2), was ultimately formed downstream of the injection well. [ABSTRACT FROM AUTHOR]

The assessment of groundwater and surface water interactions is a current topic, because research of the issue can contribute to a better understanding of the dynamics of the natural environment. Numerical modelling is a suitable tool for solving surface and groundwater interactions. Through modelling, it is possible to simulate the ongoing processes in the area under study and create a hydraulic and heat transport model. The Sihoť Water Source was chosen as the area of study because it is an anthropogenically unaffected locality. During the compilation of the model and later in the calibration process, data on the temperature and level of the groundwater table and Danube water were used, which were available thanks to the monitoring that took place at the site. In the calibration process, the sensitivity of the parameters determined by calibration was also examined. During calibration and sensitivity analysis, the hydraulic conductivity was further investigated using so-called pilot points that had been entered into the model. The accuracy of the model was verified by automatic calibration using the PEST program, while the average error value was 0.21 m for the hydraulic model and 1.04 °C for the transport model. The knowledge and methodological procedures gained by examining the issue can be applied in many other cases, such as water quality analysis, assessment of the vulnerability of the groundwater and surface water regime, or in assessing the impact of extreme precipitation and other factors. [ABSTRACT FROM AUTHOR]

Copyright of Review of the Bulgarian Geological Society is the property of Bulgarian Geological Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Coastal aquifers are host to a range of biogeochemical reactions that alter groundwater‐derived nutrient, metal, and other chemical loads to coastal ecosystems. Temperature is a strong control on microbially mediated reactions; thus, chemical reactivity in coastal aquifers may vary spatially and temporally with changes to groundwater temperature. In this study, we investigated the influence of global groundwater and sea surface temperature controls and seasonal temperature variability on biogeochemical processing in coastal aquifers using variable‐density groundwater flow, heat transport, and reactive transport models. The coupled models showed that nitrate removal efficiency in coastal aquifers increased from 5% to 88% as fresh groundwater temperature increased from 5°C to 35°C, while ocean temperature had a negligible effect on removal efficiency. Transient simulations based on monthly groundwater and ocean temperature measurements showed that denitrification and ammonification hotspots migrated seaward seasonally within warm fresh groundwater masses. The reaction hotspots were separated by colder groundwater emplaced during winter months. The reaction hotspots and nitrate plumes oscillated vertically along horizontal flow paths due to buoyancy effects between warm and cold groundwater. Comparison between transient and temperature‐equivalent steady‐state models suggests that steady‐state models adequately capture mean annual NO3− removal, but neglect local reactive transience and changes to plume geometry. The sensitivity analysis provides a first‐order estimate of the reactive potential of coastal aquifers considering globally diverse thermal regimes. The findings have implications for regional‐scale estimates of groundwater nutrient fluxes and for predicting coastal aquifer reactivity in a warming climate. Plain Language Summary: Nitrate is a groundwater contaminant that enters the subsurface from fertilizer application and septic system release and is later discharged into the ocean at concentrations that are often higher than in river runoff, damaging coastal ecosystems. Microorganisms in porewater beneath the coastline consume nitrate and remove it before it can enter the ocean. The rate that nitrate is consumed depends on temperature, so nitrate removal efficiency may vary seasonally and in different climates. In this study, we used mathematical models to study the influence of climatic and seasonal temperature variations on nutrient cycling in coastal aquifers. Our results indicate that coastal aquifers are more reactive when groundwater temperatures are warmer and that buoyant and highly reactive plumes travel through the aquifer following warm groundwater input. A better understanding of the influence of temperature on coastal aquifer reactivity is essential for the long‐term maintenance of coastal ecosystems and water resources and will aid in predicting future responses to climate change. Key Points: Fresh groundwater temperature is a strong control on coastal aquifer reactivityReaction hot spots form within and migrate with warm fresh groundwater masses emplaced during warm monthsNitrate removal efficiency varies from 5% to 88% for globally diverse thermal regimes with implications under a warming climate [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Water temperature is increasingly acknowledged as a key variable for the sustainable management of lotic environments. Thermal variability in rivers dictates in large part the ecosystem functions of these water bodies. River thermal sensitivity (TS), defined in this work as the value of the regression slope between water and air temperature (Tair) measurements, is often used to determine how river temperature regime is expected to vary as climate evolves. This study proposes a method to contextualize climate conditions during the river temperature‐monitoring period in order to define a common basis to compare TS values calculated for different stations distributed across various climatic regions in the province of Québec (Canada). Nine climate classes were defined based on Tair and precipitation. Annual climate conditions were classified according to their anomalies compared to a reference period (1981–2010). For the reference climate class ("Normal–Normal" conditions), results indicate contrasted summer TS values between Québec rivers and within rivers. Furthermore, observed summer TS variations between climate classes underline the need to account for climate conditions when studying spatial variations in river thermal sensitivity. Climate contextualization also allows us to study the potential role of previous conditions. Rivers were grouped according to their drainage basins characteristics to examine spatial variability in TS for the chosen reference climate conditions. River slope, station elevation and geographic location partly explained TS spatial variability. Useful proxies are needed to describe the relative contribution of groundwater to river temperature and to potentially improve the group classification results. [ABSTRACT FROM AUTHOR]

To collect and unify data about all geothermal resources in Serbia, a database was formed. The database allows us to perceive the geothermal resources of Serbia and their potential for utilization. Based on the data available in the geothermal database, the estimated temperatures of reservoirs, heat power, and geothermal energy utilization were calculated. The database contains 293 geothermal records (springs, boreholes) registered at 160 locations, with groundwater temperatures in the range between 20 and 111 °C. The maximum expected temperature of the reservoir is 146 °C according to the use of a SiO2 geothermometer. Some thermal water is cooled due to mixing with cold, shallow water. Geothermal resources are mostly used for balneology and recreation, and less for heating, water supply, bottling, fish and animal farms, agriculture, and industrial. 26% of all geothermal resources is used by the local population or has not been used at all. The annual utilization of geothermal energy for direct heat is 1507 TJ/yr, and the estimated capacity of geothermal energy in Serbia is 111 MWt. The results of analytical work were presented in the form of maps with a geological and hydrogeological background. Thermal waters are mostly located within an area of Tertiary magmatism. Three geothermal potential areas are identified in Serbia: Pannonian basin-Vojvodina Province, the Mačva-Srem area and area from Jošanička Banja to Vranjska Banja (southern Serbia). Based on chemical analyses, four hydrochemical facies are distinguished. Thermal water mainly belongs to the NaHCO3 or CaMgHCO3 hydrochemical facies, usually depending on the primary aquifer type: karst, karst-fissured, intergranular or fissured. [ABSTRACT FROM AUTHOR]

Abstract—The last activation of the Koryakskii volcano in 2008–2009 was accompanied by intense fumarolic and seismic activity. Volcanic activity peaked in March–April 2009 when ash plume rose to a height of 5.5 km and extended laterally over more than 600 km. To understand the dynamics of the volcanic processes and to forecast the further course of the events, it is relevant to establish whether the eruption was associated with a rise of magma to beneath the volcanic edifice or caused by fracturing of the volcano's basement and penetration of groundwater into a high temperature zone. Based on the analysis of the images from the Japanese satellite ALOS-1 using satellite radar interferometry methods, the slope displacements of the Koryakskii volcano during its last activation have been estimated for the first time. The displacements reach 25 cm and cannot be explained by the formation of a layer of volcanic ash deposits or by the slope processes. The most likely cause of the displacements should be recognized to be the intrusion of magmatic material into the volcano edifice with the formation of a fracture with its lower edge at a depth of 0.5 km above sea level, with a size of 1.0 and 2.4 km along the strike and dip, respectively, and with a dip angle from 45° to 60°. Therefore, the processes taking place beneath the volcano can be threatening to the nearby localities and infrastructure and require continuous monitoring. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Widespread groundwater pollution with nitrate (NO3−) and the finite and decreasing geogenic NO3− degradation capacity in aquifers require a better understanding of potential treatment methods. This project aimed at exploring and comparing the efficiency of four organic substances as electron donors for heterotrophic denitrification. Circulation column experiments using sediment without NO3− degradation capacity and high agricultural NO3− groundwater were conducted. Acetate, glucose, ascorbic acid, and ethanol were added to these columns in three concentration steps to induce biological denitrification, whereby also temperature dependence of denitrification rates (room temperature and typical groundwater temperature of 10°C) was taken into account. Results show denitrification with all four carbon (C) sources with intensities varying considerably between electron donors. Comparison of the two temperature approaches shows substantial differences between applied organic substances and indicates T as an important variable for denitrification. Ethanol is clearly the most effective electron donor for biodenitrification in groundwater investigated in this study, with a stronger and more effective NO3− degradation at 10°C than at room temperature. In contrast, much higher reaction rates are achieved with glucose at room temperature, compared to 10°C. Denitrification with ascorbic acid is very low at both temperatures; its addition produces biomass which repeatedly led to column clogging. In the entire test series, nitrite (NO2−) accumulation occurred more frequently and in higher concentrations at 10°C. Analysis of microorganisms shows a strong modification in microbial community in reaction to the addition of different organic C as well as between the two temperature approaches. Key Points: Higher denitrification rate with ethanol at 10°C, consequently, reaction kinetics does not generally increase with rising temperatureAddition of organic substances and temperature strongly modify the denitrifying microbial communityElectron donor selection for induced nitrate reduction depends on the groundwater temperature of the region [ABSTRACT FROM AUTHOR]

This study presents the groundwater flow and salinity dynamics along a river estuary, the Werribee River in Victoria, Australia, at local and regional scales. Along a single reach, salinity across a transverse section of the channel (~80 m long) with a point bar was monitored using time‐lapse electrical resistivity (ER) through a tidal cycle. Groundwater fluxes were concurrently estimated by monitoring groundwater levels and temperature profiles. Regional porewater salinity distribution was mapped using 6‐km long longitudinal ER surveys during summer and winter. The time‐lapse ER across the channel revealed a static electrically resistive zone on the side of the channel with a pronounced cut bank. Upward groundwater flux and steep vertical temperature gradients with colder temperatures deeper within the sediment suggested a stable zone of fresh groundwater discharge along this cut bank area. Generally, less resistive zones were observed at the shallow portion of the inner meander bank and at the channel center. Subsurface temperatures close to surface water values, vertical head gradients indicating both upward and downward groundwater flux, and higher porewater salinity closer to that of estuary water suggest strong hyporheic circulation in these zones. The longitudinal surveys revealed higher ER values along deep and sinuous segments and low ER values in shallow and straighter reaches in both summer and winter; these patterns are consistent with the local channel‐scale observations. This study highlights the interacting effects of channel morphology, broad groundwater–surface water interaction, and hyporheic exchange on porewater salinity dynamics underneath and adjacent to a river estuary. [ABSTRACT FROM AUTHOR]

A set of springs were sampled along São Miguel Island (Azores, Portugal) to proceed to the characterization of the major-ion and radon (222Rn) content. According to the selection criteria a total of 42 discharges were sampled, both during winter and summer periods, along major geological units, namely 3 springs at Sete Cidades Volcano, 4 at Nordeste Volcano, 17 at Fogo Volcano, and 18 at Furnas Volcano. Spring water temperature ranges from 12.8 to 78.1 °C in winter (mean = 23.6 °C), and from 12.6 to 76.7 °C in summer (mean = 23.9 °C), and the dataset comprehends 26 (winter) to 21 (summer) cold springs, 3 to 8 ortothermal springs, as well as 13 thermal discharges. Mean electrical conductivity is equal to 552.9 μS/cm (winter) and 550 μS/cm (summer), suggesting a short residence time, and waters are acidic to slightly basic in character (pHwinter: 4.16–7.16; pHsummer: 4.05–7.35). Groundwater chemistry is manly controlled by silicate leaching, enhanced by the water temperature, seawater spraying and by the active volcanic environment. 222Rn content ranges between 0.99 and 551.64 Bq/L (mean = 47.8 Bq/L) in winter and between 1.42 and 559.67 Bq/L (mean = 49.4 Bq/L) in summer. All the springs with anomalously higher values are located in Fogo Volcano, while the lowest radon concentrations are observed at Furnas Volcano. Groundwater temperature exerts a control over the 222Rn concentration; thus, the lower content corresponds to the most mineralized thermal waters. Springs with the higher radon content show the radiogenic contribution from uranium-rich peralkaline syenite intrusive body. Furthermore, data reveal that besides this lithologic control some waters are influenced by 222Rn migration from a deeper source towards shallower aquifers, carried by a volatile flux of CO2. [ABSTRACT FROM AUTHOR]

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Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Reservoir construction greatly affects the regional ecological environment, particularly surface water–groundwater interactions around the reservoir. Xiluodu Reservoir, a representative large‐scale reservoir in China, has had substantial impacts on surface water–groundwater interactions at the dam site since impoundment. This study analysed the dynamic characteristics of surface water–groundwater level, temperature, and hydrochemistry to determine the evolution of surface water–groundwater interaction before and after the impoundment. The levels of groundwater and some surface water rose by more than 100 m after impoundment and the water level of saturated limestone gradually stabilized, whereas basalt saturation in the affected area continued to expand. The groundwater temperature did not decrease significantly, whereas the hydrochemical types and ion contents of both surface water and groundwater experienced significant changes. Calculation of the saturation index indicated spatiotemporal changes in the saturation state of minerals. The replenishment source of each type of water and their mutual relationships were determined using cluster analysis and isotope characteristics. The results confirmed continuous, significant, and variable surface water–groundwater interactions at the dam site, which were partially reversed after impoundment. Changes in surface water–groundwater interactions were due to impoundment, the impact of which decreases with distance from the dam, as well as the unique geological conditions and artificial construction. [ABSTRACT FROM AUTHOR]

Groundwater samples from five rural agricultural villages within the Anambra basin of southeastern Nigeria were selected for the determination of their drinking quality, hydrogeochemical characteristics, corrosivity and scaling potentials. The groundwater temperature ranged from 10 to 31 °C. The pH measurements revealed that the samples are acidic. Parameters such as total dissolved solids, electrical conductivity, magnesium, calcium, sodium, chloride, bicarbonate, sulfate and nitrate recorded scores within their respective standard limits. However, potassium and phosphate pollution was observed in some samples. Synthetic pollution index was used to summarize the drinking water quality of the samples. The results showed that 88% of the samples were moderately polluted while 12% were highly polluted. Thus, the results show that they have questionable drinking water quality. Several indices used for corrosivity and scaling analyses indicated that, although the samples pose low risk of scaling (encrustation), they are severely aggressive. Hence, they are likely to deteriorate metallic water storage and distribution facilities in the study area. The predominant water facies are Cl·SO4–Ca·Mg and Cl·SO4–Na·K. Multiple hydrogeochemical and chemometric analytical models were integrated to better unravel and understand the geochemical history, processes and evolution of the groundwater. All of the models used jointly indicated that mixed, multiple processes, namely mineral-rock weathering, ionic exchange processes and anthropogenic inputs, are responsible for the predominant hydrogeochemistry observed in the study area. However, in this regard, natural, geogenic processes were identified as more important factors than those from anthropogenic activities. [ABSTRACT FROM AUTHOR]

Many buried karst areas in Iran, and in other parts of the world have not yet been mapped using detailed geological or geophysical studies to delineate susceptibility to sinkhole development. The purpose of this paper is to investigate the possibility of using the results of hydrogeochemical analysis with routine measurements of physicochemical parameters to evaluate and detect areas prone to sinkhole develop. Sixteen spatial maps were prepared using analyzed data from 77 water samples from monitoring water wells in the Kabudar Ahang, Razan, and Qahavand (KRQ) sub-catchments of the Hamadan province, western Iran. By use of geographic information system tools 16 thematic maps for physicochemical parameters (EC, pH., TDS, and groundwater temperature), major cations (Ca2+, Mg2+, Na+, and K+), anions (HCO−3, SO42−, NO3−, and Cl−), and calcite, dolomite, gypsum, and partial pressure of CO2 saturation indices (SIC, SID, SIG, and SIpCO2) were prepared. It was hypothesized that the anomalies of each parameter concentration could be consistent with sinkhole prone areas. To evaluate this assumption, the area under the Receiver Operating Characteristic (ROC) curve was calculated by 100 points as a true sinkhole pixel (50 positive true) and non-sinkhole point (50 true negative). The areas under curve of ROC for these thematic maps were calculated for the 16 variables. Results show that the dolomite and calcite saturation indices (0.49 and 0.43, respectively) are poor indicators, whereas HCO−3 and pCO2 saturation indexes (0.83 and 0.78, respectively) are good indicators of sinkhole susceptibility in the study area. The result confirmed application of hydrogeochemical anomaly analyses and the ROC validation method in covered karst can be a useful tool for prediction of sinkhole prone zones forming in region, where sparse data are available. [ABSTRACT FROM AUTHOR]

Burrowing crayfish represent 15% of total crayfish species and 32% of imperilled species. Few life history studies exist for these species and more information is needed regarding their ecology, population status, distribution, and biogeography for effective conservation efforts. Challenges to gaining such information include sampling difficulty and small sample sizes. Collection efforts may be more efficient if activity patterns can be identified for species of interest. The goal of our study was to assess specific environmental indicators of burrowing crayfish activity patterns.We evaluated activity patterns of two primary burrowing crayfish species, Lacunicambarus erythrodactylus (Simon & Morris, Proc. Biol. Soc. Wash., 127, 2014, 572) and Procambarus holifieldi (Schuster, Taylor, & Adams, Zootaxa, 4021, 2015, 1) using laser‐triggered digital photography for one‐year periods in the Bogue Chitto Creek floodplain, Dallas County, Alabama, U.S.A. We predicted that activity would be related to time of day, season, groundwater depth, and precipitation.Activity by L. erythrodactylus covaried significantly with time of day, daylength, groundwater temperature, and relative air temperature, while activity by P. holifieldi covaried with time of day, season, groundwater temperature, and relative air temperature. Additionally, burrow chimney construction by P. holifieldi covaried with daylength, groundwater temperature, relative air temperature, and precipitation.Out‐of‐burrow activity for both species was greatest at night and during periods of relatively cool groundwater temperatures and relatively warm air temperatures, which may be linked to thermal regulation behaviour. The probability of chimney construction by P. holifieldi increased with increasing daylength and decreasing precipitation and was highest during periods of cool groundwater temperatures and air temperatures. A distinct lull in activity from October through March for both species was likely to be the result of reproductive behaviours such as period of egg production and incubation within burrows.Identifying peak out‐of‐burrow activity periods for burrowing crayfish will allow collection efforts to be focused on periods of greatest activity, thereby facilitating the study of burrowing crayfish behaviour. [ABSTRACT FROM AUTHOR]

Groundwater‐dependent ecosystems represent globally rare edaphic islands of scattered distribution, often forming areas of regionally unique environmental conditions. A stable groundwater supply is a key parameter defining their ecological specificity, promoting also soil thermal buffering. Still, a limited number of studies dealt with the importance of water temperature in mire ecosystems and virtually no data exist on within‐site variation in the temperature buffer effect. Three temperature dataloggers, placed in patches potentially differing in groundwater supply, were installed in each of 19 Western Carpathian spring mire sites from May 2019 to July 2020. Spring source plots statistically differed in water temperature parameters from the plots located towards the spring mire margin, which did not significantly differ from one another. At the majority of sites, the temperature values changed gradually from spring source to mire margins, fitting the pattern expected in the groundwater temperature buffering scenario. Dataloggers placed in the spring sources were the most distinctive from the others in thermal buffering parameters in conditional principal component analysis. The difference between the spring source and its margin was on average 3.25 °C for 95th percentile of the recorded water temperature data points (i.e. warm extremes) and 1.91 °C for 5th percentile (i.e. cold extremes). This suggests that if the temperature at spring source area is considered, thermal buffering within a site may mitigate mainly warm extremes. Thus, our data may provide an important baseline for predictions of possibly upcoming changes in spring mire hydrology caused by climate change. Both warming and precipitation decrease can give rise to the loss or substantial reduction of buffering effect if the contrasting parameters now recorded at the central part shift to those found towards the margins of groundwater‐fed areas. [ABSTRACT FROM AUTHOR]

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Pore pressure is crucial in triggering debris slides and flows. Here we present measurements of groundwater pore pressure and temperature recorded by a piezometer 1.6 m below the surface on a slope susceptible to debris flows in western Norway. One of the largest oscillations in data collected over 4 years coincided with a debris flow event on the slope that occurred during storm Hilde on 15–16 November 2013. More than 100 landslides were registered during the storm. Precipitation totaled about 80–100 mm in 24 h, locally up to 129 mm, and an additional trigger factor for the landslides was a rapid rise in air temperature that caused snowmelt. In the studied slope a fraction of the precipitation first fell as snow. On 15 November, the groundwater level in the hillslope rose by 10 cm/h and reached 44 cm below the surface. At the same time, air temperature rose from 0 ∘ C to over 8 ∘ C, and the groundwater temperature dropped by 1.5 ∘ C. The debris flow probably occurred late in the evening of 15 November, when the groundwater level reached its peak. Measurements of the groundwater in the hillslope in the period 2010–2013 show that the event in 2013 was not exceptional. Storm Dagmar on 25–26 December 2011 caused a similar rise in groundwater level but did not trigger any failures. The data suggest that during heavy rainstorms the slope is in a critical state for a landslide to be triggered for a short time – about 4–5 h. [ABSTRACT FROM AUTHOR]

Subaqueous carbonates from the Devils Hole caves (southwestern USA) provide a continuous Holocene to Pleistocene North American paleoclimate record. The accuracy of this record relies on two assumptions: That carbonates precipitated close to isotope equilibrium and that groundwater temperature did not change significantly in the last 570 thousand years. Here, we investigate these assumptions using dual clumped isotope thermometry. This method relies on simultaneous analyses of carbonate Δ47 and Δ48 values and provides information on the existence and extent of kinetic isotope fractionation. Our results confirm the hypothesis that calcite precipitation occurred close to oxygen and clumped isotope equilibrium during the last half million years in Devils Hole. In addition, we provide evidence that aquifer temperatures varied by less than ±1°C during this interval. Thus, the Devils Hole calcite d18O time series exclusively represents changes in groundwater d18O values. Plain Language Summary The oxygen isotope composition of cave carbonates records changes in Earth's climate. However, the reliability of such records depends on how stable the carbonate precipitation environment was. Here, we use a novel method called dual clumped isotope thermometry that can provide simultaneous information on a carbonate's growth temperature and whether any additional fractionation processes affected its oxygen and clumped isotope signatures. Specifically, we investigated the Devils Hole caves, which provide a reference oxygen isotope time series for North America. We find that groundwater temperature did not change significantly in the last half-million years. Variations in the oxygen isotope composition of the deposited carbonates solely reflect variations in the oxygen isotope composition of the groundwater. [ABSTRACT FROM AUTHOR]

Hatchery salmonid smolts are often reared using groundwater with elevated temperatures to maximize growth. Previous work has shown that rearing hatchery smolts in surface water with a more natural thermal regime resulted in increased return rates of adult landlocked Atlantic salmon (Salmo salar). We evaluated whether landlocked Atlantic salmon reared in surface water with a natural temperature regime have altered physiological smolt characteristics compared with fish reared in groundwater with elevated winter temperatures. Hatchery fish were sampled three consecutive years from January to May. Additional fish were released as smolts, recaptured, and compared with fry-stocked smolts. Surface water smolts had earlier peaks of plasma T4, lower T3 levels, later peak cortisol, and lower gill Na+/K+-ATPase activity as compared with groundwater smolts. After release and recapture, surface water fish had elevated plasma T4 and gill Na+/K+-ATPase activity compared with groundwater fish, but less than stream-reared fish. Elevated plasma T4 in surface water fish in the hatchery and after release may have promoted imprinting and other aspects of smolt development, contributing to the higher adult return rates of a cohort reared in surface water. [ABSTRACT FROM AUTHOR]

The current study was conducted on 7 wells selected in the district of Al-Zubayr from Umm Anij farms to show some physical and chemical properties and the concentrations of nutritious salts of nitrate, nitrite, phosphates and silica in ground water. The results obtained for groundwater temperatures were almost equal between wells, with rates ranging between 22- 24 C ͦ . For chloride ion, the highest rate was in well (W7), reaching to 6812 mg / l, and the lowest rate in well (W5), which was 2599 mg / l. As for electrical conductivity, the highest rate was found in the well (W7 )reached to 8.540 mS/ cm,and the lowest rate in well( W5) was 4.933 mS / cm,the highest rate of total dissolved solids was recorded in the well (W7 )8976 mg / l and the lowest rate in the well( W5) 3923 mg / l the results showed that the highest rate of pH reached to 8.78 in (W7) well, and the lowest rate was 7.21 in well (W5), As for the turbidity, the highest rate reached to 8.790 NTU in well( W7), and the lowest was 2.303 NTU in well (W5) proportion to the values of nutrients, the nitrite values ranged as the highest value was 0.932 μg / l in well (W3 ),and the lowest value was 0.094 μg / l in well (W1), and the highest concentration of nitrate reached to 28.299 μg / l in well (W3 ),and the lowest value reached to 4.959 μg / l in well (W1). As for phosphates, the highest value reached to 1.089 μg / l for well (W3) and the lowest value was 0.879 μg / l for well (W2), and the resuits showed that the highest value of silica reached to value 72.254 μg / l in well (W3), while the lowest value was 55.700 μg / l. Well (W1) during the study period. Well water was within the permissible limits for drinking and irrigation in proportion to nitrate and nitrite values, and the concentrations of chloride ions, electrical conductivity and total dissolved solids in the study wells did not match the standard specifications of drinking and irrigation water. [ABSTRACT FROM AUTHOR]