Atomic-Scale View of Water Chemistry on Nanostructured Iron Oxide Films.

The interaction of water with solid surfaces is crucial for a wide range of disciplines, including catalysis, environmental science, corrosion, geology, and biology. In this study, we present a combined experimental and theoretical investigation that elucidates the interaction of water with a model iron oxide surface under near ambient conditions (i.e., room temperature and water vapor in the mbar range). Our findings reveal that surface hydroxylation can be controlled at the nanoscale by the local properties of the oxide film, such as local rumpling and electrostatic potential. The iron oxide surface presents alternating hydrophilic and hydrophobic domains, creating after water exposure a hexagonal pattern with a pitch of approximately 3 nm, where the highly hydroxylated regions act as nucleation centers for nanoconfined water molecule clusters.

Assessing the fate and behaviour of plant nutrients in aquaponic systems by chemical equilibrium modelling: A meta-analytical approach.

Aquaponic systems differ from hydroponics by a higher pH and higher concentrations of dissolved organic matter (DOM). This study assessed whether plant nutrient deficiencies in aquaponics are caused by lacking input of the deficient nutrients or their chemical saturation. Nine scenarios with nutrient concentrations based on Hoagland's solution and different pH (5.5, 6.5, 7.5) and DOM concentrations (0 mg L-1, 20 mg L-1) were constructed, representing theoretical hydroponic and aquaponic systems. Eventually, nutrient concentrations at equilibrium were calculated. In addition, a meta-analysis was conducted to assess whether nutrient concentrations reported in aquaponic studies could be predicted by equilibrium calculations. Theoretical results indicate that solubility thresholds cause deficiencies of P, Ca, Fe, and Cu at equilibrium due to the higher pH in aquaponics compared with hydroponics. Deficiencies in K and other plant nutrients are, meanwhile, likely caused by lacking supply through nutrient inputs at equilibrium. The presence of DOM can increase Fe and Cu solubility. However, equilibrium calculations could not predict nutrient concentrations found in literature. P was present at higher concentrations (max. 0.3 mmol L-1) than predicted (10-3-10-6 mmol L-1), indicating chemical equilibrium was not reached in the assessed systems (average hydraulic retention time = 17 d). Future studies should consider reaction rates. Furthermore, considering the low concentrations of dissolved P in all studies, a system scaling based on P instead of N might be considered.

Size-dependent effects of dams on river ecosystems and implications for dam removal outcomes.

Understanding the relationship between a dam's size and its ecological effects is important for prioritization of river restoration efforts based on dam removal. Although much is known about the effects of large storage dams, this information may not be applicable to small dams, which represent the vast majority of dams being considered for removal. To better understand how dam effects vary with size, we conducted a multidisciplinary study of the downstream effect of dams on a range of ecological characteristics including geomorphology, water chemistry, periphyton, riparian vegetation, benthic macroinvertebrates, and fish. We related dam size variables to the downstream-upstream fractional difference in measured ecological characteristics for 16 dams in the mid-Atlantic region ranging from 0.9 to 57 m high, with hydraulic residence times (HRTs) ranging from 30 min to 1.5 years. For a range of physical attributes, larger dams had larger effects. For example, the water surface width below dams was greater below large dams. By contrast, there was no effect of dam size on sediment grain size, though the fraction of fine-grained bed material was lower below dams independently of dam size. Larger dams tended to reduce water quality more, with decreased downstream dissolved oxygen and increased temperature. Larger dams decreased inorganic nutrients (N, P, Si), but increased particulate nutrients (N, P) in downstream reaches. Aquatic organisms tended to have greater dissimilarity in species composition below larger dams (for fish and periphyton), lower taxonomic diversity (for macroinvertebrates), and greater pollution tolerance (for periphyton and macroinvertebrates). Plants responded differently below large and small dams, with fewer invasive species below large dams, but more below small dams. Overall, these results demonstrate that larger dams have much greater impact on the ecosystem components we measured, and hence their removal has the greatest potential for restoring river ecosystems.

A Water-Soluble Multifunctional Probe for Colorimetric Copper Sensing, Lysosome Labelling and Live-Cell Imaging.

We report a water-soluble fluorescence and colorimetric copper probe (LysoBC1); this system can also serve for lysosome labeling and for the dynamic tracking of Cu2+ in living cells. The sensing mechanism takes advantage of the synergic action by the following three components: i) a lysosome targeting unit, ii) the spirolactam ring-opening for the selective copper chelation and iii) the metal-mediated hydrolysis of the rhodamine moiety for fluorescence enhancement. In aqueous environment the molecule acts as a fluorescent reversible pH sensor and as colorimetric probe for Cu2+ at physiological pH; the hydrolysis of the copper targeting unit resulted in a 50-fold increase of the fluorescence intensity. Most importantly, in vitro cell analyses in undifferentiated (SH SY5Y) and differentiated (d-SH SY5Y) neuroblastoma cells, LysoBC1 is able to selectively accumulate into lysosome while the copper binding ability allowed us to monitor intracellular copper accumulation into lysosome.

The colloidal stability of molybdenum disulfide nanosheets in different natural surface waters: Combined effects of water chemistry and light irradiation.

With the increasing production and application, more molybdenum disulfide (MoS2) nanosheets could be released into environment. The aggregation and dispersion of MoS2 nanosheets profoundly impact their transport and transformation in the aquatic environment. However, the colloidal stability of MoS2 remains largely unknown in natural surface waters. This study investigated the colloidal stability of MoS2 nanosheets in six natural surface waters affected by both light irradiation and water chemistry. Compared to that of the pristine MoS2 nanosheets, the colloidal stability of MoS2 photoaged in ultrapure water declined. Light irradiation induced the formation of Mo-O bonds, the release of SO42- species, and the decrease in 1T/2H ratio, which reduced negative charge and enhanced hydrophobicity. However, the colloidal stability of MoS2 photoaged in natural surface waters was increased relative to that in ultrapure water not only for the smaller extent of photochemical transformation but more importantly the surface modification by water chemistry. Furthermore, the colloidal stability of MoS2 photoaged in natural surface waters followed the order of sea water > lake water > river water. The abundant cations (e.g., Ca2+ and Mg2+) in sea water facilitated the covalent grafting (S-C bonds) of more dissolved organic matter (DOM) on MoS2 via charge screening and cation bridging, thus inducing stronger electrostatic repulsion and steric effect to stabilize nanosheets. The crucial role of the covalent grafting of DOM was further confirmed by the positive correlation between the critical coagulation concentration values and S-C ratios (R2 = 0.82, p < 0.05). Our results highlighted the dominant role of water chemistry than light irradiation in dictating the colloidal stability of MoS2 photoaged in natural surface waters, which provided new insight into the environmental behavior of MoS2 in aquatic environment.

Key factors influencing Hg levels and trends in unperturbed oligotrophic temperate and boreal lakes.

Mercury (Hg) is a toxic metal that presents a major risk to ecosystems, biota, human health, and remains a priority concern. In temperate and boreal lakes Hg and methylmercury (MMHg) are expected to vary as a function of atmospheric Hg deposition, lake water chemistry, catchment characteristics and climate variables. The aim of this study was to quantify Hg and MMHg in unperturbed oligotrophic lakes and to identify the factors controlling their distribution. We first hypothesized that lake Hg (and MMHg to lesser extent) spatial variations are linked to atmospheric deposition, catchment characteristics, and terrestrial exportation of dissolved organic carbon (DOC). We secondly examined if lake Hg concentrations have followed the decrease in atmospheric Hg emission observed between the mid-1990s to the end-2010s. We found that overall, atmospheric Hg has little impact on lake Hg and MMHg concentrations, which are both primarily influenced by DOC input originating from the forest catchment. The relationship between DOC and Hg differed between the spring and the fall, with a Hg-to-DOC ratio twice as high in spring. This seems related to snowmelt input of Hg (with a relatively reduced input of DOC) or the internal lake build-up of Hg during the ice-covered period. Of the 10 lakes intensively visited over a 20-year period, only 3 showed significant lake Hg decreases despite significant negative trends in atmospheric Hg concentrations, suggesting a lag between atmospheric and surface water temporal trends. Overall, terrestrial catchments retain around 80% of atmospheric Hg implying that large Hg pools have been built up in soils in the last decades. As such, the reduction of atmospheric Hg alone will not necessarily result in Hg decreases in lakes, since the Hg concentrations may be modulated by DOC export trends and catchment characteristics. This stresses the need to improve our understanding of the processes governing Hg transfers from catchments into lakes.

Traceability of gushing water in the MiddleRoute of the South-to-North Water Diversion (Beijing section) through the river area.

To trace the origin of the gushing water in the riverine area of the Beijing section of The Middle Route of South-to-North Water Diversion Project, a dataset was established comprising water chemistry, three-dimensional fluorescence spectra, and stable isotopes for different water bodies. Results indicated significant differences in Electrical Conductivity (EC), Total Dissolved Solids (TDS), and Ca2+ concentration among the gushing water, river water, and the water from the Middle Route of South-to-North Water Diversion Project (MRSD). Analysis using parallel factor analysis (PARAFAC) and fluorescence index revealed that dissolved organic matter (DOM) in the MRSD mainly originated from endogenous sources, while the river water and gushing water showed influences from both endogenous and exogenous sources. Nitrate sources varied among the water bodies, with distinct contributions from domestic sewage and fertilizer sources. The evaporation lines of river water and gushing water exhibited similar intercepts and slopes, but their intercepts and slopes are much smaller than those of the MRSD, suggesting stronger kinetic evaporative fractionation. In conclusion, the gushing water in the riverine area of the MRSD was determined to originate from the river, providing a fast and efficient method for gushing water source identification.

Tap water microbiome shifts in secondary water supply for high-rise buildings.

In high-rise buildings, secondary water supply systems (SWSSs) are pivotal yet provide a conducive milieu for microbial proliferation due to intermittent flow, low disinfectant residual, and high specific pipe-surface area, raising concerns about tap water quality deterioration. Despite their ubiquity, a comprehensive understanding of bacterial community dynamics within SWSSs remains elusive. Here we show how intrinsic SWSS variables critically shape the tap water microbiome at distal ends. In an office setting, distinct from residential complexes, the diversity in piping materials instigates a noticeable bacterial community shift, exemplified by a transition from α-Proteobacteria to γ-Proteobacteria dominance, alongside an upsurge in bacterial diversity and microbial propagation potential. Extended water retention within SWSSs invariably escalates microbial regrowth propensities and modulates bacterial consortia, yet secondary disinfection emerges as a robust strategy for preserving water quality integrity. Additionally, the regularity of water usage modulates proximal flow dynamics, thereby influencing tap water's microbial landscape. Insights garnered from this investigation lay the groundwork for devising effective interventions aimed at safeguarding microbiological standards at the consumer's endpoint.

Corrosion Mechanism and Electrochemical Reactions on Alloy 690 in Simulated Primary Coolant of Water-Water Energy Reactors.

During the power operation of the primary loop of a water cooled-water moderated energy reactor (WWER), the water chemistry evolves from a high-boron high-potassium composition to significantly lower concentrations of both constituents at the end of a campaign, and the Li concentration reaches ca. 0.7-0.9 ppm. In the present paper, the effect of primary water chemistry evolution during operation on the corrosion rate and conduction mechanism of oxides on Alloy 690 is studied by in situ impedance spectroscopy at 300 °C/9 MPa during 1-week exposures in an autoclave connected to a re-circulation loop. At the end of exposure, the samples were anodically polarized at potentials -0.8 to -0.1 V vs. SHE to evaluate the stability of the passive oxide. Simultaneously exposed samples of Alloy 690 were subsequently analyzed by XPS to estimate the thickness and in-depth composition of oxides. Impedance data were quantitatively interpreted using the mixed-conduction model (MCM) for oxide films. The effect of water chemistry evolution on the corrosion rate and conduction mechanism in the oxide on Alloy 690 in a primary coolant is discussed based on the obtained parameters.

The influence of atmospheric deposition and climate change driven catchment internal processes on the recovery from acidification of high-altitude Alpine lakes.

The impact of atmospheric deposition and environmental factors on catchment processes and water chemistry of 20 high-altitude Alpine lakes in Southern Switzerland was investigated over four decades. Through the analysis of input-output budgets of sulphur (S), nitrogen (N), base cations and alkalinity significant trends emerged. Notably, S and N input concentrations significantly declined since the 1980s, by approximately 78 % and 22 %, respectively, with N primarily declining after 2000. Recovery from acidification was slightly delayed, likely due to the increased release of S, possibly originating from legacy S pools, alongside the simultaneous reduction in leaching of base cations from exchange sites. Catchments heavily impacted by thawing cryospheric features increasingly released S and base cations due to enhanced weathering processes, with hardly any impact on the recovery process, as evidenced by the balanced releases of S and base cations. N output concentrations followed the decrease of N input concentrations, while the relative N retention in the catchments remained relatively stable. Recently, both input concentrations of S and N have stabilised, while output concentrations of base cations began to increase across all catchments. The trend likely arises from the stabilisation of S and N input concentrations and/or the ongoing increase in weathering rates induced by climate change. Consequently, there was a consistent rise in alkalinity output concentrations even after the stabilisation of the S and N input concentrations. Ion ratio analysis suggests that carbonation primarily drives weathering processes in catchment areas unaffected by thawing cryosphere, while in areas impacted by thawing cryosphere, sulphide oxidation (or sulphate dissolution) is the dominant process. Further recovery depends on future N deposition and the effects of climate change.

Adsorption of PFAS onto secondary microplastics: A mechanistic study.

Microplastics (MPs) are abundant in aquatic systems. The ecological risks of MPs may arise from their physical features, chemical properties, and/or their ability to concentrate and transport other contaminants, such as per- and polyfluoroalkyl substances (PFAS). PFAS have been extracted from MPs found in natural waters. Still, there needs to be a mechanistic investigation of the effect of PFAS chemistry and water physicochemical properties on how PFAS partition onto secondary MPs. Here, we studied the influence of pH, natural organic matter (NOM), ionic strength, and temperature on the adsorption of PFAS on MPs generated from PET water bottles. The adsorption of PFAS to the MPs was thermodynamically spontaneous at 25 °C, based on Gibb's free energy (ΔG = -16 to -23 kJ/mol), primarily due to increased entropy after adsorption. Adsorption reached equilibrium within 7-9 h. Hence, PFAS will partition to the surface of secondary PET MPs within hours in fresh and saline waters. Natural organic matter decreased the capacity of secondary PET MPs for PFAS through electrosteric repulsion, while higher ionic strength favored PFAS adsorption by decreasing electrostatic repulsion. Increased pH increased electrostatic repulsion, which negated PFAS adsorption. The study provides fundamental information for developing models to predict interactions between secondary MPs and PFAS.

Emergent Properties in Chemistry - Relating Molecular Properties to Bulk Behavior.

Certain properties of an object only emerge when a sufficient number of those objects are present in a definite arrangement. For example, one or two water molecules cannot said to be in a liquid state, but a drop of water can be. This concept of emergence has been studied extensively, but only occasionally discussed explicitly in the context of chemistry. In this paper, we aim to show the fruitfulness of the concept of emergence for chemical inquiry by considering four case studies of emergent chemical properties, i. e., the liquidity and freezing of water, structural properties of crystals, thermodynamical phase transitions and quantum mechanical phenomena. We show that some of these properties emerge gradually, some at discrete points, and some should be taken to emerge only when the number of constituents tends to infinity. We argue that studying the way in which chemical properties emerge presents a useful avenue for research that promises greater insight into the nature of those properties.

Photooxidation-Initiated Aqueous-Phase Formation of Organic Peroxides: Delving into Formation Mechanisms.

Formation of highly oxygenated molecules (HOMs) such as organic peroxides (ROOR, ROOH, and H2O2) is known to degrade food and organic matter. Gas-phase unimolecular autoxidation and bimolecular RO2 + HO2/RO2 reactions are prominently renowned mechanisms associated with the formation of peroxides. However, the reaction pathways and conditions favoring the generation of peroxides in the aqueous phase need to be evaluated. Here, we identified bulk aqueous-phase ROOHs in varying organic precursors, including a laboratory model compound and monoterpene oxidation products. Our results show that formation of ROOHs is suppressed at enhanced oxidant concentrations but exhibits complex trends at elevated precursor concentrations. Furthermore, we observed an exponential increase in the yield of ROOHs when UV light with longer wavelengths was used in the experiment, comparing UVA, UVB, and UVC. Water-soluble organic compounds represent a significant fraction of ambient cloud-water components (up to 500 µM). Thus, the reaction pathways facilitating the formation of HOMs (i.e., ROOHs) during the aqueous-phase oxidation of water-soluble species add to the climate and health burden of atmospheric particulate matter.

Chemical Assessment of Drinking Water Quality and Associated Human Health Risk of Heavy Metals in Gutai Mountains, Romania.

Chemical data compiled from field and laboratory studies were analysed on drinking water sources from a mountain area (Gutai Mountains) in Romania. Six physico-chemical indicators, nine anions, and twenty-one metals were determined and analysed. The results of this study showed that waters are generally rich in NH4+ and NO2-, exceeding the recommended limit of 0.5 mg NH4+/L, while some waters are rich in As, Cd, Mn and Pb, but with concentrations below the limits concerning the use of waters with drinking purposes. The applied heavy metal pollution indices (scores: 0.56-47.9) indicate that more than 50% of samples are characterized by medium pollution degrees. Based on the results obtained, it was determined that geological and human activities were influential in enriching the studied waters with the chemicals considered. Emphasizing this aspect related to pollution sources and the importance of a clean chemical status that must characterize waters used for drinking purposes, a human health risk assessment for heavy metals was implemented. The results indicated that even though the studied waters are rich in heavy metals, scores related to the risk assessment of heavy metals indicated a lack of non-carcinogenic risks for As, Mn, Cd and Cu. Nevertheless, this study and the results obtained are significant at national and international levels by offering a perspective on determining the potential pollution and associated human health risks at heavy metals in drinking water sources from a mountain area.

Effects of soil on the development, survival, and oviposition of Culex quinquefasciatus (Diptera: Culicidae) mosquitoes.

BACKGROUND: Water quality is known to influence the development and survival of larval mosquitoes, which affects mosquito-borne pathogen transmission as a function of the number of mosquitoes that reach adulthood and blood feed. Although water properties are known to affect mosquito development, few studies have investigated the link among soil properties, water quality, and mosquito development. Given the large number of ground-breeding mosquito species, this linkage is a potentially important factor to consider in mosquito ecology. In this study, we explored the effects of different soils on multiple life history parameters of the ground-breeding mosquito species Culex quinquefasciatus (Diptera: Culicidae). METHODS: Cx. quinquefasciatus larvae were reared in water combined with different soil substrates (sandy, silt, or clay loam textures) at increasing soil to water volume ratios, with and without the addition of organic matter (fish food). Gravid mosquitoes were offered different soil-water extracts to investigate soil effects on oviposition preference. RESULTS: Without the addition of organic matter, larval survival and development differed significantly among waters with different soil textures and volumes of substrate. Mosquitoes in water with clay loam soil survived longer and developed further than mosquitoes in other soil waters. Larvae survived for longer periods of time with increased volumes of soil substrate. Adding organic matter reduced the differences in larval survival time, development, and pupation among soil-water extracts. Adult female mosquitoes oviposited more frequently in water with clay loam soil, but the addition of organic matter reduced the soil effects on oviposition preference. CONCLUSIONS: This study suggests soil composition affects larval mosquito survival and development, as well as the oviposition preference of gravid females. Future studies could differentiate abiotic and biotic soil features that affect mosquitoes and incorporate soil variation at the landscape scale into models to predict mosquito population dynamics and mosquito-borne pathogen transmission.

Corrosion of Stainless Steel in Simulated Nuclear Reactor Primary Coolant-Experiments and Modeling.

In the present paper, the effect of the evolution of primary water chemistry during power operation on the corrosion rate and conduction mechanism of oxide films on stainless steel is studied by in situ impedance spectroscopy at 300 °C/9 MPa during 1-week exposure periods in an autoclave connected to a recirculation loop. At the end of the exposure period, the samples were anodically polarized in a wide range of potentials to evaluate the stability of the passive oxide. Separate samples of the same steel were simultaneously exposed to the coolant and subsequently analyzed by glow discharge optical emission spectroscopy (GDOES) in order to estimate the thickness and the in-depth composition of the formed oxides. Impedance data were quantitatively interpreted using the mixed-conduction model for oxide films (MCM) to estimate the rates of metal oxidation at the alloy/oxide interface, oxide dissolution and restructuring at the film/coolant interface, and ion transport in the protective corrosion layer.

Biogeochemical impact of historical submarine mine tailings on benthic ecosystems in the Repparfjord (Northern Norway).

Historical copper mine tailings deposited in the Repparfjord, Northern Norway, provided new insight into the biogeochemical impact of submarine tailings disposals on high-latitude coastal ecosystems. The submarine tailings disposal in the Repparfjord represents a product of mining activities between 1972 and 1979. Their environmental impact has been extensively studied during the last decade, but geochemistry of the sediment pore water, which is crucial to assess and monitor the in-situ metal leaching and bioavailability, has never been analysed. The actual impact on the benthic fauna remains poorly known. Therefore, this study couples the pore water chemistry and the foraminiferal analysis obtained from selected sediment cores (gravity core, multicore, box cores) to examine metal stability and the past and current status of the foraminifera community. We measured down-core sulfate and trace metal concentrations and Eh-Ph and applied the Shannon index, the AZTI's Marine Biotic Index (F-AMBI) index and the foraminiferal abnormality index. This study confirms the ongoing leaching of Cu from the underlying mine tailings and release across the sediment-water interface. Leaching of Ni, Zn and Pb have been attributed to weathering of natural bedrock lithologies. The original benthic foraminiferal community disappeared almost entirely during the disposal period, and now it is dominated by stress-tolerant and opportunistic species like Bulimina marginata and Spiroplectammina biformis. Anyhow, against previous assumptions, the community composition changed, while the overall diversity and abnormalities (FAI) shell formation is unaffected by elevated Cu concentrations.

Identification of mine water sources using a multi-dimensional ion-causative nonlinear algorithmic model.

Based on the nonlinear algorithmic theory, the R-SVM water source discrimination model and prediction method were established by using the piper qualitatively to compare the differences between the ionic components and R-type factor approximation indicator input dimensions. Taking the mine water samples of Zhaogezhuang Coal Mine as an example, according to the chemical composition analysis of the water samples from different monitoring points, six indexes of Na+, Ca2+, Mg2+, Cl-, SO42- and HCO3- were selected as the discrimination factors. According to the water characteristics of each aquifer and the actual needs of discrimination, the water inrush sources in the mining area were divided into four categories: The goaf water is class I, Ordovician carbonate is class II, Sandstone fracture water from the 13 coal system is class III, and Sandstone fracture water from the 12 coal system is class IV. Taking 56 typical water inrush samples as training samples, 11 groups for prediction samples, establish the input index as typical ion content, output as water source type, using SPSS statistics and MATLAB to realize the R-SVM water source discriminant analysis model, automatically establishing the mapping relationship between the water quality indexes and the evaluation standards, which can achieve the purpose of rapid and accurate discrimination of the water sample data. The results showed that the accuracy of the R-SVM model classification was 90.90% in the verification of the water source discrimination example of Zhaogezhuang mine and the coupled model has high accuracy, good applicability and discriminant ability, and has certain guiding significance for the prevention and control of water damage and the related field work.

Understanding Flow Fouling Deposition and Solute Hideout-Return Behavior at the Phase Change Interface.

Nuclear energy is a competitive green energy, yet corrosion deposition and boron hideout on pressurized water reactor fuel cladding surfaces could cause localized corrosion and power shift, resulting in huge safety and economic risks. Alleviation of these problems requires the understanding of the corrosion deposition mechanism and related boron behavior. In this study, we explore corrosion product deposition in typical fuel assembly channels under subcooled boiling conditions and propose a boron hideout and return mechanism to explain the reason for the failure of the power reduction inhibiting a power shift. Porous corrosion depositions with the same morphology and thickness as the real depositions in a fuel cycle are obtained in a week via the accelerated deposition method simulating a real subcooled boiling and water chemical environment. Stronger subcooled boiling generates more bubbles, resulting in higher supersaturation of corrosion products at the gas-liquid interface. The corresponding precipitated stable crystals are smaller, and the formed deposition layer is looser and thicker with smaller particles. On the basis of the above characterizations, the effect of subcooled boiling, solute concentration, and water chemistry on the corrosion deposition mechanism is revealed. High-resolution characterization methods indicate that boron hides within the depositions mainly in the form of H3BO3 and Li2B4O7. The boron coolant concentration increases by 307.9 ppm after power reduction, confirming the return behavior of porous hidden boron. Hidden boron return behavior brings potential challenges for estimating critical conditions and plant response operations. The results of this study provide a precise method for understanding the corrosion product deposition and boron hideout-return behavior to further develop mitigation strategies for power shift and localized corrosion security issues.

Identifying spatial variability of water chemical characteristics and groundwater discharge in Hulun Lake integrated remote sensing data and chemical components.

The frozen period interaction of groundwater and lakes is crucial for hydrological properties and aquatic ecology in cold and arid regions. In this study, we investigate the spatial hydrochemical characteristics, influencing factors in the Hulun Lake basin. The hydrochemical type of lake water exhibits Na-HCO3-SO4-Cl, while river shows a primary classification of Na-Ca-HCO3. Groundwater in the eastern and western regions is characterized by Na-SO4-Cl and Na-HCO3, respectively. Silicic acid and ion exchange predominantly influence groundwater chemistry in the western region, whereas evaporation and concentration play a major role in the eastern region. Total dissolved solids, Cl-, and F- emerge as the primary influencing factors of hydrochemical components in the Hulun Lake basin. Ion content decreased from the southern to the northern region, with the lowest value occurring near the Urson River. The high-temperature water body is primarily distributed in the central and southern regions of the lake. Based on characteristic ions and partial characteristics of ice surface temperature, the potential groundwater discharge areas near the inlet of the Xinkai River, the central and southern region are determined. This study reveals the hydrochemical characteristics, vertical ice distribution, and provides a scientific foundation for water resource management in cold and arid regions.