Industrial effluents and N-nitrosamines in karst aquatic systems: a study on distribution and ecological implications.

The discharge of electroplating wastewater, containing high concentrations of N-nitrosamines, poses significant risks to human health and aquatic ecosystems. Karst aquatic environment is easily impacted by N-nitrosamines due to the fragile surface ecosystem. However, it's still unclear in understanding N-nitrosamine transformation in karst water systems. To explore the response and transport of nine N-nitrosamines in electroplating effluent within both karst surface water and groundwater, different river and groundwater samples were collected from both the upper and lower reaches of the effluent discharge areas in a typical karst industrial catchment in Southwest China. Results showed that the total average concentrations of N-nitrosamines (∑NAs) in electroplating effluent (1800 ng/L) was significantly higher than that in the receiving river water (130 ng/L) and groundwater (70 ng/L). The dynamic nature of karst aquifers resulted in comparable average concentrations of ∑NAs in groundwater (70 ng/L) and river water (79 ng/L) at this catchment. Based on the principal component analysis and multiple linear regression analysis, the electroplating effluent contributed 89% and 53% of N-nitrosamines to the river water and groundwater, respectively. The results based on the species sensitivity distribution model revealed N-nitrosodibutylamine as a particularly toxic compound to aquatic organisms. Furthermore, the average N-nitrosamine carcinogenic risk was significantly higher in lower groundwater reaches compared to upper reaches. This study represents a pioneering effort in considering specific N-nitrosamine properties in evaluating their toxicity and constructing species sensitivity curves. It underscores the significance of electroplating effluent as a primary N-nitrosamine source in aquatic environments, emphasizing their swift dissemination and significant accumulation in karst groundwater.

An improved technology for monitoring groundwater flow velocity and direction in fractured rock system based on colloidal particles motion.

The colloidal borescope, using colloidal particle motion, is used to monitor the flow velocities and directions of groundwater. It integrates advanced techniques such as microscopy, high-speed photography, and big data computing and enjoys high sensitivity at the micron level. However, In the same well, the groundwater flow velocity monitored by colloidal hole mirror is varies greatly from that obtained by conventional hydrogeological monitoring, such as pumping test. In order to solve this problem, the stability catcher and stratified packer are designed to control the interference of the vertical flow in drilling, and to monitor the flow velocity and direction of groundwater velocity at the target aquifer and target fracture. Five wells with different aquifers and different groundwater types were selected for monitoring in south-central China. The instantaneous velocity and direction are converted into east-west component and north-south component, the average velocity and direction is calculated according to the time of 10 min, and the particle trajectory diagram is established. Based on these results, it proposed a concept of cumulative flow velocity. Using curve-fitting equations, the limits of cumulative flow velocities as the monitoring time tends to infinity were then calculated as the actual flow velocities of the groundwater. The permeability coefficient of aquifer is calculated by using the fissure ratio of aquifer, hydraulic slope and flow velocity, and compared with the permeability coefficient obtained by pumping test. The results are as follows: (1) The variation coefficient of the instantaneous flow velocity measured at the same depth in the same well at different times is greater than that of the time average flow velocity and greater than that of the cumulative flow velocity. The variation coefficient of the actual velocity is the smallest, indicating that the risk of using the actual flow velocity is lower. (2) The variation coefficient of the flow rate monitored at different depths in the same well is mainly controlled by the properties of the aquifer. The more uniform water storage space in the aquifer, the smaller the variation coefficient. (3) The comparison between the permeability coefficient obtained by monitoring and the permeability coefficient obtained by pumping test shows that the flow of structural fissure water controlled by planar fissure is more surface flow, and the results are consistent. When the groundwater flow is controlled by pores and solution gaps, the flow channel is complicated, which is easy to produce turbulent flow, and the result consistency is poor. (4) According to different research accuracy requirements, different monitoring and calculation methods can be selected for different aquifers and groundwater types. Researches show that, the permeability coefficient calculated for the actual flow velocity in well DR01 is the same as that calculated for the pumping test. The aquifer characteristics reflected by the coefficient of variation of the actual flow velocity in the same aquifer are more realistic. The pumping test method obtains the comprehensive parameters of a certain aquifer, and this method can be used to monitor a certain fissure. In this paper, the new technology developed for monitoring, and the new algorithm established for data processing, can accurately obtain the flow velocity and direction of groundwater, using capsule hole mirror monitoring method. The key parameters of hydrogeology can be obtained by using one well, which can reduce the time and cost input and improve the work efficiency.

Hydrogeological controls on microbial activity and habitability in the Precambrian continental crust.

Earth's deep continental subsurface is a prime setting to study the limits of life's relationship with environmental conditions and habitability. In Precambrian crystalline rocks worldwide, deep ancient groundwaters in fracture networks are typically oligotrophic, highly saline, and locally inhabited by low-biomass communities in which chemolithotrophic microorganisms may dominate. Periodic opening of new fractures can lead to penetration of surface water and/or migration of fracture fluids, both of which may trigger changes in subsurface microbial composition and activity. These hydrogeological processes and their impacts on subsurface communities may play a significant role in global cycles of key elements in the crust. However, to date, considerable uncertainty remains on how subsurface microbial communities may respond to these changes in hydrogeochemical conditions. To address this uncertainty, the biogeochemistry of Thompson mine (Manitoba, Canada) was investigated. Compositional and isotopic analyses of fracture waters collected here at ~1 km below land surface revealed different extents of mixing between subsurface brine and (paleo)meteoric waters. To investigate the effects this mixing may have had on microbial communities, the Most Probable Number technique was applied to test community response for a total of 13 different metabolisms. The results showed that all fracture waters were dominated by viable heterotrophic microorganisms which can utilize organic materials associated with aerobic/facultative anaerobic processes, sulfate reduction, or fermentation. Where mixing between subsurface brines and (paleo)meteoric waters occurs, the communities demonstrate higher cell densities and increased viable functional potentials, compared to the most saline sample. This study therefore highlights the connection between hydrogeologic heterogeneity and the heterogeneity of subsurface ecosystems in the crystalline rocks, and suggests that hydrogeology can have a considerable impact on the scope and scale of subsurface microbial communities on Earth and potentially beyond.

Multi-year in situ hydrogeochemical monitoring of hard rock lithium mine tailings in a large-scale experimental pile.

Spodumene, a lithian mineral found in granitic pegmatites, is a major source of lithium. In situ, multi-year and large-scale (>10s of tons) predictive hydrogeochemical studies can be of great value for informing mine waste rock and tailings management, not least because the material is exposed to the actual climate where it is meant to be stored. However, such studies are rare given their cost and size, and previous ones have focused mainly on sulfide-bearing materials. An experimental field cell filled with spodumene beneficiation tailings was built at the Whabouchi lithium mine site in northern Québec (Canada) and monitored during four consecutive years. In parallel, column laboratory kinetic testing on the same material was conducted for water quality parameters to compare the effect of testing scales on the geochemical behavior. Geochemical results and release rates were overall similar between laboratory and field, and consistent with previously published laboratory results for materials from the same site. The leachates were neutral to slightly alkaline, with ions from feldspars (Ca > Na > K) and residual spodumene (Li) being notable solutes. Concentrations for most solutes surveyed remained higher in the field after four years than in columns at the end of the experiment. One major difference between laboratory and field was a brief (less than 2 years) increase in iron concentrations from the field cell, resulting in Fe-oxyhydroxides precipitation, that was not observed in laboratory. The source of this iron is arguably residual ferrosilicon (used for dense medium separation) and this difference is attributed to the different testing conditions and configurations in the laboratory versus in situ. Field hydrogeological results highlight strong seasonal patterns and the rapid response of this sand-like, sulfide-poor material to ambient temperature changes and wetting-drying events. The tailings both wet and drain rapidly and easily given their water retention curve and the range of matrix suctions recorded during frost-free months. Net infiltration through the tailings was estimated to represent 55% of total precipitation in summer (June-October) 2021. This study provides a comprehensive assessment of the environmental behavior of hard rock lithium mine tailings under real, sub-arctic climatic conditions and outlines similarities and differences between laboratory- and field-generated geochemical results.

4D microvelocimetry reveals multiphase flow field perturbations in porous media.

Many environmental and industrial processes depend on how fluids displace each other in porous materials. However, the flow dynamics that govern this process are still poorly understood, hampered by the lack of methods to measure flows in optically opaque, microscopic geometries. We introduce a 4D microvelocimetry method based on high-resolution X-ray computed tomography with fast imaging rates (up to 4 Hz). We use this to measure flow fields during unsteady-state drainage, injecting a viscous fluid into rock and filter samples. This provides experimental insight into the nonequilibrium energy dynamics of this process. We show that fluid displacements convert surface energy into kinetic energy. The latter corresponds to velocity perturbations in the pore-scale flow field behind the invading fluid front, reaching local velocities more than 40 times faster than the constant pump rate. The characteristic length scale of these perturbations exceeds the characteristic pore size by more than an order of magnitude. These flow field observations suggest that nonlocal dynamic effects may be long-ranged even at low capillary numbers, impacting the local viscous-capillary force balance and the representative elementary volume. Furthermore, the velocity perturbations can enhance unsaturated dispersive mixing and colloid transport and yet, are not accounted for in current models. Overall, this work shows that 4D X-ray velocimetry opens the way to solve long-standing fundamental questions regarding flow and transport in porous materials, underlying models of, e.g., groundwater pollution remediation and subsurface storage of CO2 and hydrogen.

Sustaining aquifers hydrologically, economically, and institutionally: Policy analysis of the Ogallala in New Mexico.

Groundwater discharge exceeding recharge threatens sustainable aquifer water use internationally. Interest remains high in discovering more hydrologically sustainable and economically affordable measures to protect these aquifers. Previous research has conducted various aquifer assessments. Some work has investigated costs and benefits of various plans that would limit aquifer pumping. Despite notable advances in this kind of analysis, little published work to date has unified these elements into a science-based integrated framework to inform more sustainable aquifer policy design. This work's novel contribution is to integrate analysis of hydrology, economics, institutions, and policy into a unified scientific framework to inform choices on more sustainable pumping strategies while protecting economic activity for agricultural and urban water-using sectors. It does so by conceptualizing, formulating, designing, and applying a mathematical programming framework to replicate historically observed pumping patterns in parts of the Southern and Central High Plains Ogallala Aquifer region in New Mexico, USA. We first calibrated the optimization framework to replicate the historically observed data. We then go on to identify least cost pumping caps that would have partly restored the aquifer to its 2014 level by 2020, while comparing the performance of four other partial aquifer protection policy measures. Findings indicate a surprisingly low cost that could have been incurred to partially protect the aquifer over that period. However, these low costs are complicated by (1) decreasing water quality outside of the irrigated regions and (2) focusing of lateral inputs to a narrower zone of depression around the irrigated regions. These findings carry important implications for identifying more sustainable aquifer management plans internationally. The work's importance comes from its capacity to inform policy debates over a range of water shortage sharing plans, while respecting institutional constraints governing equitable burden sharing.

Analysing agricultural plant protection product concentrations in groundwater in Germany: Nationwide database with site and compound insights.

Pesticides from agricultural practices are among the most pressing reasons why groundwater sources do not reach the good chemical status standards as required by the European Water Framework directive. Complementary to previous federal pesticide reports, we analysed groundwater-monitoring data from 13 German Länder assembled in a database consisting of 26.192 groundwater measuring sites sampled between 1973 and 2021 of in total 521 parent compounds and metabolites. This study focuses on agricultural plant protection products. The monitored substance spectrum and site density developed over time and differs between Länder. More than 95 % of all samples lie below the respective (multiple) limits of quantification (LOQ). We thus report the frequency of exceedance above concentration thresholds, which allows to compare measurements temporally and spatially. Pesticide detections were found in all aquifer types, land uses and well screen depths. Most detections of higher concentrations were found in agricultural areas, at shallow screen depth in porous aquifers. Karst aquifers showed also a higher percentage of samples in higher concentration classes. Metabolites with high mobility and persistence were found in higher concentration ranges. Herbicides and metabolites thereof dominate the top 20 of pesticides that most frequently exceed 0.1 µg L-1. The ranking for 2010-2019 includes both authorised and banned compounds and their occurrence is discussed in the context of their mobility, persistence and underlying monitoring density. Yearly exceedance frequencies above 0.05, 0.1 µg L-1 and higher thresholds of metazachlor and its esa-metabolite, and national sales data of the parent compound did not show a temporal correlation in subsequent years. This study stresses the need for the harmonisation of heterogeneous pesticide data. Further, a characterisation of the groundwater data used to analyse pesticide occurrence in selected concentration ranges for relevant site factors and compound properties and provides a pesticide ranking based on exceedance frequencies is provided.

Groundwater modelling reports fail to comply with guideline recommendations for model reproducibility.

Computer models are routinely used to underpin critical decision-making for projects that impact groundwater systems. Modelling results are communicated through technical reports, which advise regulators and other stakeholders of groundwater impacts, thereby informing approvals, project restrictions and monitoring requirements. Several guidelines and texts are available to instruct groundwater model development and reporting. In seven of the eight guidelines/texts reviewed, it is recommended that modelling reports (or a model archive) contain sufficient information for an external party to rebuild the model. This study examined that expectation (assumed to be "best practice") by reviewing 25 groundwater modelling reports from eight countries and assessing whether the information contained therein was sufficient (or an archive was provided) to rebuild the model on which the report was based. The reports were characterised based on 18 model components (e.g., aquifer properties, boundary conditions, etc.), and the availability of sufficient information in the report to rebuild each one. The "rebuildability" of model components was classified as: (a) reproducible (from the report), (b) reproducible but assumptions needed, and (c) not reproducible. The Analytical Hierarchical Process was employed to rank the reports based on the reproducibility of the models they describe. Only one of the 25 reports provided adequate information to rebuild the model, while one other report was accompanied by a model archive, resulting in two cases of model reproducibility, contrary to guideline recommendations. This outcome reflects problems with reproducibility in the wider scientific community. We conclude that modelling reports need to provide more detailed information to be compliant with best practice or model archives ought to be made available. Addressing this issue will ensure that stakeholders have access to the information needed to properly assess whether future groundwater impacts have been reliably evaluated.

Overexploitation assessment in an urban karst aquifer: The case of Sete Lagoas (MG), Brazil.

Overexploitation of groundwater in urban karst aquifers can lead to negative consequences such as land subsidence, depletion of springs and lakes, and water pollution. It can also have indirect effects such as environmental, socio-economic, and political instability. In the municipality of Sete Lagoas, Brazil, the long-term effects of extensive groundwater extraction have been observed and studied over the years. This paper analyzes the response of the karst aquifer to urban, industrial, and climatological changes that may have contributed to changes in the aquifer over the last four decades. The results show that groundwater extraction has exceeded the average aquifer recharge since the year 2000. From the 1980s, the number of wells has steadily increased due to unplanned urban development, resulting in higher demand for groundwater. In the 2010s, pumping from tubular wells (7.39 × 107 m3/yr) exceeded the maximum recharge capacity of the aquifer (7.33 × 107 m3/yr). These wells are mainly concentrated in two areas: the central urban zone and the industrial sector. As a result, kilometer-long cones of depression have formed, changing the aquifer from confined to unconfined within these regions. According to the census data, about 67% of the wells remain unidentified. The average annual recharge to the aquifer is estimated to be 5.68 × 107 m3/yr, which accounts for 12% of the average annual rainfall in the region. Climatological trends indicate an incipient decrease in precipitation and an increase in temperature, suggesting a potential decrease in future aquifer recharge. In addition, only 17% of the area has high infiltration rates ranging from 35% to 75%. The current situation in Sete Lagoas is one of overexploitation of groundwater resources, which could be mitigated by localized reduction of groundwater consumption and implementation of effective management strategies to increase aquifer recharge.

Use of Microbiological and Chemical Data to Evaluate the Effects of Tourism on Water Quality in Karstic Cenotes in Yucatan, Mexico.

Cenotes are spectacular karst formations in Yucatan, Mexico, often used for recreation. However, their impact on water quality has yet to be explored in detail. Therefore, during Easter, water samples were collected from four cenotes to identify variations in water quality associated with the presence of tourists. PCO of water quality, before (PH) and during Holy Week (HW) in 2019, explained 49.02% of the total variation. The indicators contributing to the first principal coordinate's variation were Sr, K, sulfate, and chloride (0.89). Whereas, alkalinity, temperature, conductivity, nitrate, and ORP contributed to the second PC. PERMANOVA indicated a significant interaction between "cenote" and "condition" factors, and post hoc paired comparisons indicated significant differences between PH and HW conditions. Significant correlations varied among the four cenotes as the result of hydrogeological differences. Whereas, numbers of visitors were correlated with at least one fecal-matter indicator, demonstrating anthropogenic influence on the cenotes' water quality.

Small Mediterranean coastal Lagoons Under Threat: Hydro-ecological Disturbances and Local Anthropogenic Pressures (Size Matters).

Mediterranean coastal lagoons are affected by multiple threats (demographic pressures, eutrophication, climate change) expected to increase in the future and impact the ecosystem services provided. Conservation norms and scientific studies usually focus on large lagoons (> 0.5 km2) due to their economic importance, while they ignore smaller lagoons. These are poorly understood and often unprotected, despite their prevalence within the Mediterranean region and their importance. Qualitative and quantitative characterisation of small lagoons, in terms of functioning and sensitivity to global and local changes, are needed to develop appropriate management strategies. For this purpose, this work provides the first inventory of all Corsican lagoons and has investigated three of them of small size (Arasu, Santa Giulia, Balistra), characterised by contrasting anthropogenic contexts (highly modified/disturbed, medium disturbance, quasi-pristine). At the regional level, 91 of the 95 lagoons identified are < 0.5 km2, making Corsica a good example for the study of small Mediterranean lagoons. The three case studies showed differences in their seasonal biogeochemical cycles and phytoplankton communities (biomass, diversity, photosynthetic efficiency). Arasu and Santa Giulia lagoons showed an increase in watershed urbanisation (+ 12% and + 6% in 30 years), high phytoplankton biomass, low diversity and blooms of potentially harmful dinoflagellates. Conversely, Balistra lagoon showed a good status overall, but some anthropogenic pollution sources within its watershed. This study demonstrates the importance of small lagoons at regional and Mediterranean scale, and provides knowledge on studied local sites but also potential applications elsewhere. The importance of an integrated approach considering lagoons within their adjacent connected systems (watershed and sea) and anthropogenic contexts is highlighted. Supplementary Information: The online version contains supplementary material available at 10.1007/s12237-023-01182-1.

[Hydrochemical Characteristics and Control Factors of Groundwater in Shunping County, Hebei Province].

In order to study the chemical characteristics and ion source of groundwater and further serve the scientific development and management of water resources in Shunping County. A total of 33 groups of karst water and 12 groups of pore water samples were collected systematically in Shunping County, and the hydrochemical types, composition characteristics, and main controlling factors of various types of groundwater were analyzed by using Gibbs diagram, ion ratio relation, and multivariate statistical analysis methods, and the contribution rates of various sources to groundwater solutes were evaluated. The results showed that the pore water and karst water in the study area were weakly alkaline, with TDS ranging from 245.89 to 430.00 mg·L-1 and 223.54 to 1347.80 mg·L-1, respectively. The anion components of groundwater were mainly HCO3- and Ca2+. Groundwater in the study area could be grouped into PW1 and PW2 pore water and KW1, KW2, and KW3 karst water. PW1 and KW1 were HCO3-Ca·Mg type, PW2 was HCO3·Cl-Ca·Mg type, KW2 was HCO3·NO3-Ca·Mg type, and KW3 was SO4-Ca·Mg type with high salinity. The weathering of carbonate rock mainly composed of dolomite and silicate rock mainly composed of albiar and potassium feldspar were the main material sources of groundwater, and their contributions to each water body were 39.69% to 66.13% and 11.87% to 58.38%. Sewage discharge and fertilizer use in human activities had significant effects on KW2 groundwater and PW1, PW2, and KW1 groundwater, respectively. In addition, the contribution rate of atmospheric precipitation to each water body ranged from 1.09% to 7.94% on average.

Contrastive mechanisms of groundwater ammonium enrichment in different hydrogeologic settings.

Although high levels of geogenic ammonium in groundwater have been widely reported, the mechanisms controlling its heterogeneous distribution are not yet well understood. In this study, a comprehensive investigation of hydrogeology, sediments, and groundwater chemistry was coupled with a set of incubation experiments to reveal the contrasting mechanisms of groundwater ammonium enrichment at two adjacent monitoring sites with different hydrogeologic settings in the central Yangtze River basin. Significant differences were found in the ammonium concentrations of groundwater at two monitoring sites, with the ammonium concentrations in the Maozui (MZ) section (0.30-5.88 mg/L; average of 2.93 mg/L) being much higher than those in the Shenjiang (SJ) section (0.12-2.43 mg/L; average of 0.90 mg/L). For the SJ section, the aquifer medium had a low organic matter (OM) content and a weak mineralization capability, leading to a limited potential for geogenic ammonium release. Moreover, due to the presence of alternating silt and continuous fine sand layers (with coarse grains) above the underlying confined aquifer, the groundwater was in a relatively open environment with oxidizing conditions, which may have promoted the removal of ammonium. For the MZ section, the aquifer medium had a high OM content and a strong mineralization capability, leading to a much higher potential for geogenic ammonium release. Furthermore, due to the presence of a thick and continuous muddy clay layer (aquitard) above the underlying confined aquifer, the groundwater was in a closed environment with strong reducing conditions, which was conductive to the storage of ammonium. Larger sources of ammonium in the MZ section and greater consumption of ammonium in the SJ section contributed collectively to the significant differences in groundwater ammonium concentrations. This study identified contrasting mechanism of groundwater ammonium enrichment in different hydrogeologic settings, which can help explain the heterogeneous distribution of ammonium levels in groundwater.

[Hydrochemical Characteristics and Control Factors of Pore-water in the Middle and Upper Reaches of Muwen River].

In order to study the hydrochemical characteristics and ion sources of pore water in the middle and upper reaches of the Mouwen River, 29 groups of pore-water samples were collected in the Laiwu Basin. The main ion characteristics and their controlling factors of pore-water in this area were analyzed by using correlation and principal component analysis, Piper trigram, and Gibbs diagram methods. The main material sources of pore water in this area were revealed. The results showed that HCO3-, NO3-, SO42-, and Ca2+ were the main anions and cations in the pore water of the middle and upper reaches of the Mouwen River. With TDS >1000 mg·L-1 as the standard, the normal water chemistry type was mainly HCO3·NO3·SO4-Ca and HCO3·SO4-Ca·Mg, whereas the abnormal water chemistry type was mainly NO3·Cl-Ca. The chemical evolution of groundwater was mainly influenced by rock weathering, cation alternation adsorption, and human activities. Na++K+ mainly came from silicate weathering and dissolution, and HCO3-, Ca2+, and Mg2+ came from calcite weathering and dissolution involving carbonate and sulfuric acid. Alternation adsorption of cations and weathering of silicate rock provided a surplus of Ca2+ and Mg2+ for pore water. Industrial and mining activities such as domestic sewage mixing, agricultural planting activities, and iron and coal mining changed the chemical composition of pore water, especially NO3- exceeding the standard, which has become the main problem of the local groundwater chemical environment.

A literature review on pumping test analysis (2000-2022).

Accurate and precise values of hydrodynamic parameters are needed for groundwater modeling and management. Pumping test in the aquifer is the standard method to estimate the transmissivity, hydraulic conductivity, and storage coefficient as the key hydrodynamic parameters. Analytical solutions with curve matching and numerical modeling are two methods to estimate these parameters in the aquifer. Graphical analyses are commonly applied to time-drawdown/water table data which are time-consuming and approximate. Graphical type-curve methods as promising tools are used extensively in water resources studies, while applying these methods is still new in pumping test analysis. In the current study, the first effort based on our knowledge, we have reviewed the literature type-curve graphical methods in pumping test analysis. To achieve this goal, we reviewed and compared the journal articles regarding the characteristics and capabilities of the modeling process from 2000 to 2022. We have clustered the reviewed papers into graphical, modeling, and hybrid categories. Then, a comprehensive review of the selected papers was presented to delineate the highlight of every paper. This review could guide researchers in pumping test analysis. Also, we have presented various recommendations for future research to improve the quality of hydrodynamic parameter estimation.

Remote monitoring of minewater rebound and environmental risk using satellite radar interferometry.

The cessation of dewatering following coalfield abandonment results in the rise of minewater, which can create significant changes in the local and regional hydrogeological regime. Monitoring such change is challenging but essential to avoiding detrimental consequences such as groundwater contamination and surface flooding. Inverse modelling methods using satellite radar interferometry (InSAR) have proven capable for retrospectively mapping minewater level changes, however, there is a need for the capability to remotely monitor changes as they occur. In this study, ground deformation measurements obtained from InSAR are used to develop a method to remotely monitor the spatio-temporal rise of minewater, which could be implemented in near real-time. The approach is demonstrated over the Horlivka mining agglomeration, Ukraine, where there is no other feasible approach possible due to a lack of safe ground access. The results were blindly validated against in-situ measurements before being used to forecast the time until minewater will reach the natural water table and Earth's surface. The findings reveal that, as a result of military conflict in Donbas, an environmental catastrophe could occur where potentially radioactive minewater is forecast to reach the natural water table between May and August of 2024.

UAV-borne LiDAR revolutionizing groundwater level mapping.

In hydrogeological research, the systematic and periodic measurement of the piezometric level is fundamental to assess aquifer storage, identify recharge and discharge areas, define flow directions and to infer the balance between inputs and withdrawals. Furthermore, knowledge of this variable and its fluctuations is essential for the efficient management and protection of groundwater resources. In this work, a novel methodology is proposed for the remote acquisition of piezometric information from traditional large-diameter wells, using drone-borne LiDAR observations. The workflow developed consists of different stages, from flight planning and parameter setting, to point cloud generation, data processing and validation and its statistical treatment to extract piezometric information. This methodology has been applied in a small coastal aquifer with numerous wells that have served as monitoring points. The UAV-LiDAR has enabled the straightforward obtention of measurements of the piezometric level with very high vertical accuracies (RMSE of 5 cm) with minimum and maximum residuals of -8.7 and 7.9 cm respectively. Likewise, the method has shown vertical accuracies 3 times better than those inferred from the official DTM of best resolution available in Spain, which is usually used in hydrogeological works. Since the technique provides absolute values of the piezometric level, it eliminates the need for laborious levelling work prior to hydrogeological campaigns. This method has proved to be an effective alternative/complementary technique to traditional measurements of the piezometric level, allowing to monitor extensive or inaccessible areas over short periods of time and to potentially reduce gaps in hydrogeological databases.

A 350,000-year history of groundwater recharge in the southern Great Basin, USA.

Estimating groundwater recharge under various climate conditions is important for predicting future freshwater availability. This is especially true for the water-limited region of the southern Great Basin, USA. To investigate the response of groundwater recharge to different climate states, we calculate the paleo recharge to a groundwater basin in southern Nevada over the last 350,000 years. Our approach combines a groundwater model with paleo-water-table data from Devils Hole cave. The minimum water-table during peak interglacial conditions was more than 1.6 m below modern levels, representing a recharge decline of less than 17% from present-day conditions. During peak glacial conditions, the water-table elevation was at least 9.5 m above modern levels, representing a recharge increase of more than 233-244% compared to present-day conditions. The elevation of the Devils Hole water-table is 3-4 times more sensitive to groundwater recharge during dry interglacial periods, compared to wet glacial periods. This study can serve as a benchmark for understanding long-term effects of past and future climate change on groundwater resources.

Steam caps in geothermal reservoirs can be monitored using seismic noise interferometry.

Harvesting geothermal energy often leads to a pressure drop in reservoirs, decreasing their profitability and promoting the formation of steam caps. While steam caps are valuable energy resources, they also alter the reservoir thermodynamics. Accurately measuring the steam fraction in reservoirs is essential for both operational and economic perspectives. However, steam content estimations are very limited both in space and time since current methods rely on direct measurements within production wells. Besides, these estimations normally present large uncertainties. Here, we present a pioneering method for indirectly sampling the steam content in the subsurface using the ever-present seismic background noise. We observe a consistent annual velocity drop in the Hengill geothermal field (Iceland) and establish a correlation between the velocity drop and steam buildup using in-situ borehole data. This application opens new avenues to track the evolution of any gas reservoir in the crust with a surface-based and cost-effective method.

Hydrogeological Knowledge from Below: Water Expertise as a Republican Common in Early-Modern Venice.

This essay looks at early-modern Venice hydroculture as a case of episteme from below. The forms of water knowledge it developed were multilayered and collective in their essence and solidly rested on a social experiential basis that was rooted in labour (especially fishing) and practices (especially water surveying and engineering). In accordance with the city's republican esprit (and correspondent political values), its episteme emerged as the encounter and negotiation between various institutions and groups: the fishermen of San Niccolò in Venice, the practitioners of the water magistrature and political authorities. This essay explores the institutional settings of this water culture, seen as an instance of bottom-up epistemic construction. It especially addresses three historical instances: firstly, a seventeenth century program to map public waters in order to block their alienation for private fish farming; secondly, water officers' interviews with fishermen aimed to assess the state of the lagoon hydromorphology and, thirdly, fishing regulations. Venice communitarian and circular forms of knowledge production are here contrasted to an opposite paradigm, which was embodied by the Galileian mathematician and Rome courtier, Benedetto Castelli. His interactions with the Republic of Venice on water management and his approach to hydraulic problems are revealing of an elitist and abstract understanding of scientific knowledge that guided political decisions from above without taking in any consideration the opinions of the 'vulgar'. While his science was the expression of a top-down political epistemology, Venetian water knowledge was more egalitarian. It left room for exchange, inclusiveness and bottom-up codification; it valued the gathering of different experiences (including the fishermen's practical knowledge of their waters) and rested on a concrete and systemic (organicist) understanding of natural-anthropic processes.