Local River Water Research Articles

Nontargeted Analysis of Reactive Nitrogenous Compounds in Suwannee River Standard Reference Materials and Authentic River Water Samples.

Concerns over toxic nitrogenous disinfection byproducts (N-DBPs) necessitate identifying their precursors in source water. Natural organic amino compounds are known precursors to N-DBPs. Three Suwannee River (SR) standard reference materials (SRMs), humic acids (HA), fulvic acids (FA), and natural organic matter (NOM), are commonly used to study DBP formation, but the chemical makeup of amino compounds in SRSRMs remains largely unknown. To address this, we combined stable hydrogen/deuterium isotope labeling, HDPairFinder bioinformatics, and nontargeted high-performance liquid chromatography-high-resolution mass spectrometry (HPLC-HRMS) to characterize these compounds in SRSRMs. This method classifies reactive amines, provides accurate masses and MS/MS spectra, and quantifies intensities. We identified 2707 high-quality features with primary and/or secondary amines in SRSRMs and 75% of them having an m/z < 300. Across all three SRSRMs, 327 amino features were detected, while 856, 794, and 200 unique features were found in SRNOM, SRHA, and SRFA, respectively. In North Saskatchewan River (NSR) samples, a total of 6449 amino features were detected, 818 of them matched those in SRSRMs, and 87% of them were different between the two rivers. Using chemical standards, we confirmed 10 compounds and tentatively identified 5 more. This study highlights similarities and differences in reactive N-precursors in SRSRMs and local river water, enhancing the understanding of geo-differences in reactive N-precursors in different source waters.

지방정부의 댐 하천관리의 물공급에 관한 사례분석: 유지유량 관리를 중심으로

The purpose of this study was to find solutions for local government dam river management and water supply for maintenance flow. For this purpose, based on data collected and organized on items to be included in the system related to the environment around Unmun Dam and Dongchang Stream, a comparative review of the policy status of other local governments and environmental facilities was conducted, and case analysis was conducted focusing on domestic and international cases. The local government's maintenance flow management plan for water supply in dam river management is, first, to manage the river flow in a stable manner throughout the year in order to perform the smooth function of the river, and second, to pump water to maintain the basic flow rate of the river. A reverse pumping method that sends water from downstream to upstream, and third, artificial supply of soil through flooding or flushing discharge to improve the environment of the river downstream of the dam were proposed. As a result, we tracked changes in the natural ecological environment of Dongchang Stream after the construction of Unmun Dam and proposed dam operation plans and flood control policies to derive implications such as ecological environment restoration, flood prevention measures in downstream areas, and local economy revitalization measures.

Stable isotopes of oxygen and hydrogen in precipitation and river water in Georgia

Abstract The article presents the first comprehensive evaluation of the isotopic composition of precipitation and runoff in Georgia. It is based on data from the monitoring of δ18O and δ2H in monthly precipitation at eleven precipitation stations and monthly runoff from five large, mostly nested catchments in Georgia, collected between the years 2013 and 2022. The data represent different climatic and altitudinal conditions ranging from the wet western part of Georgia affected by the Black Sea to the dry eastern part of the county presumably affected also by the air masses from the Caspian Sea. Specific conditions affecting the isotopic composition of precipitation and river water seem to occur close to the main ridge of the Greater Caucasus Mountains. We defined the National Meteoric Water Line (NMWL) and the National River Water Line (NRWL) for Georgia as well as the Local Meteoric Water Lines (LMWLs) and River Water Lines (RWLs) for individual precipitation stations and river gauges and investigated their slopes and intercepts. Altitude gradients of δ18O and δ2H in the rivers were similar to those in precipitation (–0.16‰ and –1.2‰ per 100 m of altitude for δ18O and δ2H, respectively). The rivers were supplied from precipitation of the colder part of the year (November/December to March/April) while the isotopic composition of precipitation in the remaining warmer part of the year was clearly detached from that of the rivers. The isotopic signal in precipitation was dampened in the rivers by a factor of 5–6. The scaled line-conditioned excess (lc-excess*) did not indicate any significant deviations of river waters from meteorological conditions in the catchments.

Arsenate removal from water by Ti electrocoagulation: Main influencing factors, response surface optimization, and potential mechanisms

This paper detailedly investigated the efficacy and mechanism of As(V) removal by Ti electrocoagulation (Ti EC) using batch test. The Box-Behnken design method with 3 factor 3 level was used to optimize main process parameters (electrode distance, current density, and initial pH). The obtained optimal parameters for the maximum arsenic removal at 30 min were as follows: electrode distance of 9.2 mm, current density of 15.5 A/m2, and initial pH of 6.5. Initial pH had a significant impact on the arsenic removal (P < 0.01). The quadratic polynomial mathematical model was developed. Flocs characterization (TEM, XRD, XPS, FTIR, and zeta potential) combined with adsorption test were conducted for the mechanism analyses. Results showed that the flocs generated by Ti EC (rutile TiO2 as main crystalline phase) were nano-aggregates and had high reactivity. The As(V) removal mechanisms by Ti EC mainly involved flocculation, flotation, surface complexation, hydroxyl exchange, and coprecipitation. The As(V) removal efficiency of Ti EC was also investigated using real water samples (0.2 mg As/L) collected from the local lake and river waters. The corresponding As(V) removal efficiencies was up to 99.0 % and 99.2 %, respectively, within 30 min and at a CD value of 25 A/m2. This study shows that Ti EC has many advantages such as green safety, low cost, and high efficiency, thereby it is a potential water treatment technology for As(V) removal.

Hydrogen and Oxygen Isotopic Characteristics and Influencing Factors of "Three Waters" in Shandian River Basin

In this study, we collected precipitation from February 2020 to February 2022 and the surface water and groundwater in the wet (August) and dry (October) periods of 2021 in the Shandian River Basin. Stable isotope technology was used to analyze the temporal and spatial changes in the hydrogen and oxygen stable isotopes of the "three waters" in the basin to explore the relationship between water isomorphs and environmental factors and to reveal the water conversion relationship using the end element mixing model. The results showed that the slope and intercept of the local precipitation line were smaller than the local atmospheric precipitation line. The water vapor mainly came from westerly water vapor, polar air mass, and East Asian monsoon circulation. The precipitation isotope had a significant temperature effect. In terms of time, the isotopes of surface water and groundwater were more enriched in the dry season than those in the wet season, and the d-excess values of surface water and groundwater were lower than the global average, indicating strong local evaporation. Spatially, the δ18O value of the rivers had the same change characteristics in the wet and dry seasons, showing gradual enrichment from the upstream to the downstream, and the groundwater δ18O high value area was unevenly distributed in space, with groundwater δ18O values becoming more depleted with the increase in burial depth. The highest slope of the groundwater water line was 7.87 in the wet season, which was very close to the slope of the local atmospheric precipitation line and river water line, indicating that there was a complex hydraulic connection between the "three waters" in the wet season. The surface water in the study area was mainly supplied by precipitation during the wet season and then by groundwater runoff. These results can provide a theoretical basis for revealing the hydrological cycle in arid and semi-arid areas.

Stable and reusable acrylic ion-exchangers. From HMIs highly polluted tailing pond to safe and clean water

The application of several ion-exchange resins (IExR) with amino and amphoteric functionalities in batch retention of heavy metal ions (HMIs) (Cu(II), Fe(II), Mn(II), Zn(II)) from mono- and multicomponent simulated waters and from real polluted water collected from tailings pond of Tarnita (Suceava, Romania) sterile dump is deeply herein explored. The tested resins exhibited high sorption capacities, as evaluated by atomic absorption spectrometry, results supported by infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. The effect of pH on the IExR sorption capacity in competitive condition evidenced the optimum pH where IExR sorption efficiency is maximum. Reutilization of IExR in six consecutive sorption/desorption/regeneration cycles showed their renewable sorption properties. Wheat germination tests demonstrated that the Tarnita collected water had a high toxic effect whereas the resulted supernatant after batch sorption was nontoxic. The study shows that HMIs content after IExR sorption is under the admitted maximum level for surface water, and represents an important step on the efforts to solve the environmental problem in Tarnita area, by removing the main contaminants found in the local river water.

AIE-active phenothiazine based Schiff-base for the selective sensing of the explosive picric acid in real water samples and paper-based device

A highly selective and sensitive AIE fluorescent chemosensor based on phenothiazine and ethylene diamine was synthesized (DPTZ-SB) for the exclusive detection of picric acid (PA). Interestingly, DPTZ-SB can sense PA exclusively over five other competitive explosives, due to the specific complexation ability of DPTZ-SB towards PA. For the better mechanistic understanding, Stern-Volmer, Modified Stern-Volmer and Job’s plot were employed, which showed the limit of detection and binding constant to be 0.2 ppb and 4.05 × 1010 M−1, respectively, and the stoichiometric ratio of DPTZ-SB:PA as 1:2. The values are promising as compared to the AIE fluorophores reported for PA sensing recently. The sensing mechanism was elucidated using DFT studies and 1H NMR titration experiment, which revealed the active involvement of the imine groups of the Schiff base in the complexation process. Furthermore, in order to broaden the applicability, the probe DPTZ-SB was applied in real water samples obtained from the local river, lake and tap water. Interestingly, a paper based fluorescent sensor was devised by embedding DPTZ-SB on the filter paper and was analyzed by a handheld UV lamp. Under UV light illumination, the paper-based sensor exhibited prominent fluorescence quenching in the presence of PA, which can be conveniently visualized. Moreover, the color-scanning application available in smart phones was coupled with the paper-based sensor to quantitate the scanometric assays. On a parallel note, DPTZ-SB showed excellent aggregation induced enhanced emission (AIEE) property. In fact, a 9.4-times enhancement in the photoluminescence (PL) intensity was noted for a 90:10 H2O:DMF of DPTZ-SB as compared to that in pure DMF. Therefore, the multifaceted applicability of the Schiff base has been explored, particularly in the fields of PA explosive detection device in real life samples and AIEE.

Carbon Quantum Dots Based Chemosensor Array for Monitoring Multiple Metal Ions

The simultaneous identification of multiple metal ions in water has attracted enormous research interest in the past few decades. We herein describe a novel method for multiple metal ion detection using a carbon quantum dots (CQDs)-based chemosensor array and the CQDs are functionalized with different amino acids (glutamine, histidine, arginine, lysine and proline), which act as sensing elements in the sensor array. Eleven metal ions are successfully identified by the designed chemosensor array, with 100% classification accuracy. Importantly, the proposed method allowed the quantitative prediction of the concentration of individual metal ions in the mixture with the aid of a support vector machine (SVM). The sensor array also enables the qualitative detection of unknown metal ions under the interference of tap water and local river water. Thus, the strategy provides a novel high-throughput approach for the identification of various analytes in complex systems.

Column-Test Data Analyses and Geochemical Modeling to Determine Uranium Reactive Transport Parameters at a Former Uranium Mill Site (Grand Junction, Colorado)

The long-term release of uranium from residual sources at former uranium mill sites was often not considered in prior conceptual and numerical models, as contaminant removal focused on meeting radiological standards. To determine the reactive transport parameters, column tests were completed with various influent waters (deionized water, site groundwater, and local river water) on sediment from identified areas with elevated uranium on the solid phase in (1) vadose-zone (VZ) sediments, (2) saturated-zone sediments with higher organic carbon content, and (3) both vadose- and saturated-zone sediments with additional gypsum content. The gypsum was precipitated when low-pH, high-sulfate, tailings fluids or acidic waste disposal water were buffered by natural aquifer calcite dissolution. In general, the resulting uranium release was higher in the sediments with greater uranium concentrations. However, the addition of deionized water (DI) to the VZ sediments delayed the uranium release until higher-alkalinity groundwater was added. Higher-alkalinity river water continued to remove uranium from the VZ sediments for an extended number of pore volumes, with the uranium being above typical standards. Thus, river flooding is more efficient at removing uranium from VZ sediments than precipitation events (DI water in column tests). Organic carbon provides a stronger uranium sorption surface, which can be explained with geochemical modeling or a larger constant sorption coefficient (Kd). Without organic carbon, the typical sorption in sands and gravels is easily measurable, but sorption is stronger at lower, water-phase uranium concentrations. This effect can be simulated with geochemical modeling, but not with a constant Kd. Areas with gypsum create situations in which geochemical sorption is more difficult to simulate, which is likely due to the presence of uranium within mineral coatings. All the above mechanisms for uranium release must be considered when evaluating remedial strategies. Column testing provides initial input parameters that can be used in future reactive transport modeling to evaluate long-term uranium release rates and concentrations.

Phytic acid functionalized magnetic adsorbents for facile enrichment of trace rare earth elements in environmental water, digested atmospheric particulates and the extracts followed by inductively coupled plasma mass spectrometry detection

Phytic acid (PA) functionalized magnetic adsorbents was synthesized through simple process. The functionalized sorbents are featured with core-shell structure, good magnetism, chemical stability, selectivity, and fast adsorption/desorption dynamics for the preconcentration of trace rare earth elements (REEs). With the aid of inductively coupled plasma mass spectrometry detection, the prepared Fe3O4@SiO2@PA sorbents were employed for the separation and enrichment of 15 REEs from environmental water and atmospheric particulates with different sizes. Under the optimal conditions, the method presented an enrichment factor of 300-fold and low detection limits (0.002–1.1 ng/L) for 15 REEs, with the relative standard deviations of 1.4–4.4%. Environmental water samples were analyzed by the proposed method, and 15 REEs of 0.08–5.80 ng/L were found in local rainwater and river water. The REEs concentration in locally collected fine particulate matter was 0.01–0.93 ng/m3, 0.03–1.70 ng/m3 and 0.03–2.47 ng/m3 of REEs were found in inhalable particulate matter and total suspended particulate samples, respectively. The bioaccessibility of REEs in PM2.5 was evaluated by using Gamble's solution extraction, which was calculated to be 0.73–5.46%.

Electrocatalytic determination of hydrazine concentrations with polyelectrolyte supported AuCo nanoparticles on carbon electrodes

Gold–cobalt alloy nanoparticles (AuCo NPs) deposited on a screen-printed carbon electrode (SPCE) surface modified with a combination of polystyrene sulfonate (PSS) and poly-3,4-ethylenedioxythiophene (PEDOT) is demonstrated for monitoring the direct oxidation of hydrazine. The surface morphology and properties of PSS:PEDOT supported AuCo NPs modified carbon electrodes were characterized using field-emission scanning electron microscopy, X-ray diffraction, and energy dispersive spectroscopic analysis. The current change with respect to the electrocatalytic oxidation of hydrazine on AuCo NPs/PSS:PEDOT/SPCE was used for the quantitative analysis in conjunction with cyclic, linear sweep, and differential pulse voltammetries alongside chronoamperometry (CA). The voltammetric response for the oxidation of hydrazine using AuCo NPs/PSS:PEDOT/SPCE was also compared with those of bare SPCE and PSS:PEDOT/SPCE. Under optimum conditions using CA, the modified electrode offered a linear range from 0.5 to 1000 μM, a sensitivity of 1.64 µA µM−1 and a limit of detection of 0.17 µM. The stability, reproducibility, sensitivity, and selectivity were also investigated. Finally, the AuCo NPs/PSS:PEDOT/SPCE platform was employed to determine native hydrazine concentrations in local river water samples.

Facile fabrication of surface molecularly imprinted magnetic polydopamine for selective adsorption of fluoroquinolone from aqueous solutions

To address problems such as environmental accumulation, improved methods are required for the detection and analysis of fluoroquinolones. Herein, we prepared a surface molecularly imprinted polymer (MIP) based on dopamine-coated magnetic nanoparticles. The performance of this MIP as a novel adsorbent for fluoroquinolones was analyzed using high-performance liquid chromatography. Furthermore, the morphology and physicochemical properties of the prepared material were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, thermogravimetric analysis, Brunauer–Emmett–Teller surface area analysis, and vibrating sample magnetometry. The synthesized molecules consisted of a core–shell constitution with a Fe3O4 nucleus and a polydopamine enclosure, the surface of which was imprinted using gatifloxacin as a template molecule. The obtained polymers had a high specific surface area, good superparamagnetism, and excellent selectivity of the target molecules. Under optimal adsorption conditions, the ultimate loading capacity of gatifloxacin on the MIP was 51.9 mg/g, with an equilibrium adsorption time of 30 min and an imprinting factor of 2.24. After six cycles, the adsorption capacity of this adsorbent did not decrease significantly. For the analytical characteristics of the method, we inserted the application part of the sample in the local river water. Through the spiked recovery of the three FQs aqueous solutions, it was found that their spiked recovery, LOD, and LOQ were 84.1–91.9%, 6.4–9.9 ng mL−1, and 17.8–34.5 ng mL−1, respectively. Owing to its adsorption selectivity and recyclability, this magnetic MIP is a promising adsorbent for sample separation and pretreatment applications.

Hydrological Changes in Restricted Basins: Insights From Strontium Isotopes on Late Miocene‐Pliocene Connectivity of the Eastern Paratethys (Dacian Basin, Romania)

AbstractThe Dacian Basin was uniquely situated to record late Miocene hydrological changes that influenced depositional environments and faunal dispersal patterns in Central Eurasia's mega‐lake Paratethys. Differences between the high strontium isotope ratio (87Sr/86Sr) of the waters from Lake Pannon and local Carpathian rivers and low 87Sr/86Sr of the Eastern Paratethys (Black Sea ‒ Caspian Sea) allow a thorough investigation of connectivity and water fluxes in the transient Dacian Basin. We present a detailed 87Sr/86Sr record for the Dacian Basin, which provides an exceptional record of basin connectivity from the latest Tortonian (ca. 7.7 Ma) until the early Pleistocene (ca. 1.8 Ma). Data show that a late Tortonian transgression (7.6–7.4 Ma) started with an incursion of Eastern Paratethys waters into the Dacian Basin, after which local rivers became the dominant source for the mostly freshwater environments of the early Messinian. The regional Maeotian‐Pontian transitional interval (6.3–5.9 Ma) records a second incursion of Eastern Paratethys waters, but this time with an additional marine (Mediterranean) influx coinciding with a short‐lived salinity incursion. During the Messinian Salinity Crisis of the Mediterranean, the Dacian Basin progressively connected with the Eastern Paratethys (5.9–5.5 Ma), after which it became restricted during the peak Mediterranean lowstand (5.5 Ma) and filled with Lake Pannon and local river water (5.5–5.3 Ma). During the Plio‐Pleistocene, the Dacian Basin reconnected with the, at that time isolated, Black Sea, which shows similar 87Sr/86Sr as in the Last Glacial Maximum.

Participatory research to monitor lake water pollution

Abstract A participatory research team, concerned about water quality around Lake Geneva, particularly in the Montreux Bay region where some were lifeguards, ran sampling campaigns to determine summertime levels of lake water pollution. The participants were brought together serendipitously through a course organized by academic researchers and ‘biohackers’ from the community laboratory, Hackuarium. After discussion about lifeguards’ gastrointestinal and dermatological ailments each season, the decision to pursue this participatory research project was made. In order to assess water quality, thereby testing the hypothesis that unsuspected pollution enters the lake each summer season, microbiological plating of water samples was proposed. Volunteers collected and analysed water samples over summer seasons (8 weeks in 2016, 2017 and 2020) from three sites around Montreux Bay, with tap and local river water samples as controls. Contamination of lake water was measured using standard microbiological methods, with growth media allowing quantitative assessment of abundance of several bacterial species. In particular, the focus was to quantify Escherichia coli, the classic bioindicator organism for raw sewage contamination. These open science data reveal peaks of bioindicator and other bacterial pollution in lake water samples during all sampling years. For the initial two sampling campaigns, increased microbial burdens occurred during a popular music festival, and were not simply dependent upon rainfall. In contrast, only scattered, lower level bioindicator pollution events occurred across the sampling period during the pandemic summer of 2020, when the festival was cancelled. This study confirms the power of participatory research: dedicated people on a budget can do meaningful environmental monitoring. These analyses suggest that better management, both to support water quality monitoring and for event organization, is essential, as sewage treatment facilities near many popular festivals, internationally, may need to cope with increased wastewater from visitors.

Quercus robur survival at the rear edge in steppe: Dendrochronological evidence

Climate change is altering forest ecosystems worldwide, particularly in steppe landscapes, where the rare tree communities are challenged with steadily increasing droughts. In the steppe of Eastern Europe, amid dry conditions, Quercus robur occupies mostly riverine habitats and ravines. Here we study the climate sensitivity and drought vulnerability of a Q. robur population located at the rear edge of the species range, in the steppe of Ukraine. The population occupies two adjacent but clearly contrasting in their microclimatic conditions sites: a river floodplain and a steep-sloping river bank. We develop tree earlywood, latewood, and total ring width site-level chronologies and evaluate their relationship with regional climate variables and the local river's water level using response function analysis. We find that trees growing in the floodplain and at the steep river bank have exhibited slightly different growth patterns. The trees at the flooded site have benefited from water proximity, which facilitated their earlywood growth. These trees have responded positively to the current May and previous September precipitation and previous and current May temperatures. At the non-flooded site, the trees have experienced warm temperatures and the lack of precipitation in June. The extreme drought episodes have triggered a decrease in the latewood and total ring width in trees from both sites. We established that oak growth in the floodplain had been depressed by an unknown stressor around 1900, therefore limiting our ability to identify the more beneficial steppe habitat for Q. robur conclusively. Nevertheless, our results provide a dendrochronological evidence of Q. robur survival in a dry steppe environment and lend new insights into local microclimatic factors contributing to it.

The river water influence on cationic and anionic dyes collection by nickel foam with carbonized metal-organic frameworks and carbon nanotubes

Nickel foams provide an easy and interesting template for novel strategies for the creation of micro and nanomaterials composites. Metal foam showed potential applications for preparation electrodes for supercapacitors and Li-ion batteries. Currently, foams are often studies as containments adsorbent. Here, we develop a nickel foam with graphene layer and carbon nanotubes growth from carbonized metal-organic, for adsorption of the cationic dye (Methylene Blue) and anionic dye (Acid Red 18) from aqueous solution. The metal-organic framework used in this composite is based on cobalt elements that after carbonization formed as a particle and serves as a carbon nanotubes catalyst. The kinetic models and mechanism of the adsorption of the dyes were studied. These nickel foam with carbon nanotubes adsorption efficiency are also evaluated in the reference sample (distilled water) and environmental water (local river water). The results unravel the composite shows a higher adsorption capacity of Methylene Blue then Acid Red 18. This study also showed that composite shows higher Methylene Blue adsorption efficiency in environmental water than in the distilled water. The effect of higher Methylene Blue adsorption was not observed for the Acid Red 18. However, the reported nickel foam and carbon nanotubes composite feature better selectivity of the anionic dye over cationic adsorption, from the mixture of both dyes. This study shows what is the real perspective in waste adsorption from river water by the presented nanocomposite. The design of the composite shows an easy way to use as an adsorbent.

Isotopic temporal and spatial variations of tropical rivers in Thailand reflect monsoon precipitation signals

AbstractStable isotopic compositions (δ18O andd‐excess) from 25 rivers in Thailand were analysed monthly during 2013–2015. Results indicated that monsoon precipitation fundamentally influences the river isotopes. The overland flow supplied from monsoon precipitation and human‐altered flow regimes produces considerable isotopic variability. Spatial and temporal variations were observed among four principal geographical regions. The seasonality of monsoon precipitation in mountainous Thailand produced large variations in isotopic compositions because most rainfall occurred during the southwest monsoon, and dry conditions prevailed during the northeast monsoon. The northern and northeastern regions are mountainous, highland areas. Low δ18O values were found in these regions, likely because of altitude effects on precipitation. Conversely, monsoonal precipitation continually supplies rivers in southern Thailand all year round, producing higher and more consistent δ18O values than in the other regions. The Chao Phraya plain in the central region experienced enrichment of δ18O river runoff related to evaporation in irrigation systems. Larger catchment areas and longer residence times resulted in more pronounced evaporation effects, producing lower values ofd‐excess and local river water line slopes compared with precipitation. The isotopic differences between river waters and precipitation were utilized to determine river recharge elevations and water transit time. The methods presented here can be used to explore hydrological interactions in other tropical river basins.

Unravelling the hydrological effects on spatiotemporal variability of water chemistry in mountainous rivers from Southwest China

AbstractUnderstanding the effects of hydrological processes on solute dynamics is critical to interpret biogeochemical processes. Water chemistry and isotopic compositions of surface water (δ18Ow and δDw) were investigated in rivers from Southwest China to study the effects of hydrological variability on biogeochemical processes. The inverse relationship between deuterium excess (d‐excess) and δ18Ow could be ascribed to non‐equilibrium fractionation processes, and the slope of the Local River Water Line was much lower than the Local Meteoric Water Line, suggesting the post‐precipitation evaporation pattern. The evaporation fraction (1–f) was estimated by the d‐excess method, varying from 0.01 to 0.18. (1–f), was a function of water temperature and drainage mean elevation, indicating that evaporation easily occurs at high temperatures in low‐elevation regions. The hydrological processes co‐varied with solute dynamics in the river network, and fluid transit time and temperature were likely responsible for the co‐variations. Also, we found that hydrological processes played an important role in solute dynamics through shifting the geochemical processes (e.g., enrichment, water‐rock reaction, photosynthesis, and secondary mineral precipitation). This study highlights that biogeochemical processes co‐vary with hydrological processes, and we suggest that investigating hydrological processes can help to understand biogeochemical processes.

A study of kudurs used by wild animals located on the water sources high in REE content in the Caucasus Nature Reserve

One of the theories explaining the reasons for geophagy, which was proposed earlier by the authors of the article, consists in the assumption that animals need rare-earth elements (REE). In order to test this hypothesis, we studied the chemical composition of spring waters in the territory of the Caucasus Nature Reserve at three kudurs along the Achipsta River, as well as at the Mamaevsky kudur (southwestern slope of the Pshekish mountain). At the Mamaevsky kudur, we also studied the chemical composition of earth consumed by animals, and the species, age and gender composition, seasonal and daily activity of ungulate animals-visitors of the kudur. It was determined that the most active visitors of the Mamaevsky kudur were European bison (Bison bonasus) with one activity peak during the rut, in July. The frequency of visits to the kudur by red deer (Cervus elaphus) was 4 times lower with the highest peak activity in April and a lower peak in August. Only in one of four water sources at the Mamaevsky kudur there was an elevated concentration of Na (by 7 times). In the other three the concentration was comparable to the local river water. The waters of two "sodium-free" springs had increased concentrations of REE (by 5-8 times). Geophagic earths near the Mamaevsky springs are decomposition products of siltstone and sandstone shale rocks of the Jurassic age consisting of clay minerals (illite mixed with smectite, and chlorites)-from 42 to 45%, and quartz and feldspar (in total up to 50%) mixed with Fe and Ca carbonates. The chemical composition of acid extracts (0.1N HCl, pH = 1.0) from consumed earth showed the highest extractability of Ca and Fe. In trace elements, Sr, Ba, Zn, Cu, Ni, Co, V, light lanthanides, and Y are most actively extracted. Na is extracted at 0.03-0.1g/kg. The sodium bicarbonate spring water consumed by animals at kudurs on the Achipsta River had Na contents 70-300 times, and REE contents 25-40 times higher than that in the river water. The revealed facts do not contradict the hypothesis that the desire for geophagy in animals in the Caucasus (in addition to the long-known "urge" for Na) can be also related to the properties of lanthanides group elements exchange in the body.

Design Aspects, Energy Consumption Evaluation, and Offset for Drinking Water Treatment Operation

Drinking water treatment, wastewater treatment, and water distribution are energy-intensive processes. The goal of this study was to design the unit processes of an existing drinking water treatment plant (DWTP), evaluate the associated energy consumption, and then offset it using solar photovoltaics (PVs) to reduce carbon emissions. The selected DWTP, situated in the southwestern United States, utilizes coagulation, flocculation, sedimentation, filtration, and chlorination to treat 3.94 m3 of local river water per second. Based on the energy consumption determined for each unit process (validated using the plant’s data) and the plant’s available landholding, the DWTP was sized for solar PV (as a modeling study) using the system advisor model. Total operational energy consumption was estimated to be 56.3 MWh day−1 for the DWTP including water distribution pumps, whereas energy consumption for the DWTP excluding water distribution pumps was 2661 kWh day−1. The results showed that the largest consumers of energy—after the water distribution pumps (158.1 Wh m−3)—were the processes of coagulation (1.95 Wh m−3) and flocculation (1.93 Wh m−3). A 500 kW PV system was found to be sufficient to offset the energy consumption of the water treatment only operations, for a net present value of $0.24 million. The net reduction in carbon emissions due to the PV-based design was found to be 450 and 240 metric tons CO2-eq year−1 with and without battery storage, respectively. This methodology can be applied to other existing DWTPs for design and assessment of energy consumption and use of renewables.