Specific Ion Concentrations Research Articles

A recyclable ZnIn2S4/PAN photocatalytic nanofiber membrane for boosting visible light hydrogen evolution in seawater without cocatalyst

Using seawater for photocatalytic hydrogen production is always a highly promising direction. However, traditional powdered photocatalysts encounter challenges like ion interference and difficulty in reuse. To address these issues, we have combined the photocatalyst ZnIn2S4 (ZIS) with a polymer (PAN) using electrospinning technology to produce a composite photocatalytic ZIS/PAN nanofiber membrane. In aqueous solution, the ZIS/PAN nanofiber membrane achieves a maximum hydrogen evolution rate of approximately 1836 μmol/g/h, which is 3.37 times that of ZIS particles. Additionally, cyanide groups on PAN fibers can capture a small portion of photogenerated electrons, which then adsorb ions from seawater, reducing their impact on the photocatalyst and demonstrating excellent seawater hydrogen production performance. At specific ion concentrations, the membrane's activity is 20 % higher than in aqueous solution. Moreover, it overcomes the limitations of powdered photocatalyst structures, enabling device integration that facilitates easy recovery and reuse.

Water quality impact on flotation Response: A focus on specific ions and temperature

Plant water recycling causes an accumulation of ions in the process water which may affect plant processes since processing routes are water intensive. Seasonal temperature differences affect the water quality through variation of the available recycled water within the plant between the summer and winter seasons. The objective of this study was therefore to investigate the effect of specific ions and temperature, relevant to onsite process water recycling and temperature variations brought about by seasonal changes, on the separation of gangue from valuable minerals in batch flotation of a low-grade Cu-Ni-PGE ore. Water and solids recoveries were impacted by Ca2+ and SO42-. At high SO42- concentrations, an increase in Ca2+ increased the mass of water and solids recovered. An increase in SO42- alone caused an increase in copper recovery whilst decreasing the copper grade. S2O32- alone affected the nickel recovery. An increase in S2O32- caused an increase in nickel recovery whilst the nickel grade was affected by the interaction of S2O32- and temperature. Furthermore, copper showed similar trends as those observed for nickel in the responses for the mineral grade. At high S2O32- concentration there was no observable change in the nickel and copper grades when temperature increased. At low S2O32- concentrations, an increase in temperature decreased the nickel and copper grades. In addition to the interactive effect of temperature and S2O32-, nickel was more temperature sensitive in comparison to copper. The study demonstrated that there are specific ion concentration ranges beyond which flotation performance was adversely affected and other ranges beyond which no observable effect on flotation was visible. Based on this understanding, it may be possible to predict the ideal operating conditions for the number of water recycles in a plant. The higher ionic concentrations and their corresponding ionic strengths resulted in a more stable froth in comparison to lower ionic concentrations and consequently an improvement in the recoveries.

Selective Ion Sensing Organic Electrochemical Transistors Suitable for Blood Analysis

AbstractOrganic electrochemical transistors (OECTs) have gained considerable attention due to their ability to simultaneously transduce and amplify ion‐based biological signals into electronic signals in bioelectronics. In this study, functionalized OECTs capable of detecting specific ion concentrations in aqueous solution and blood serum are investigated and described. Sodium, the most concentrated cation in the human body, is chosen as the target analyte due to its critical role in maintaining normal bodily functions such as blood pressure, nerve and muscle function, and fluid balance. These sodium ion sensors work at low source‐drain voltage, Vds = 0.4 V and gate voltage, Vg = 0 V, and demonstrate a high sensitivity of 126 μA dec−1 and a high selectivity over different cations. Furthermore, the OECT biosensors are employed to determine sodium concentration in more complex environments and demonstrated a log‐linear response within the physiological range of sodium in blood serum, ranging from 100 to 160 mm. In the final part of the study, the transistor‐based sensor is fabricated in a small‐footprint neural probe configuration and its sensing capability is investigated. These characteristics open up new opportunities for applications in wearable and implantable electronics.

Estrogen's Tissue-Specific Regulation of the SLC26A6 Anion Transporter Reveal a Phenotype of Kidney Stone Disease in Estrogen-Deficient Females: A Systematic Review.

Kidney stone formation is an intricate process that involves a disruption in the interplay of the multiple organs and systems involved in regulating the concentration of specific ions in the body. Women who have gone through menopause are susceptible to kidney stone disease.This systematic review aims toinvestigatethe potential influence of estrogen on kidney function and oxalate homeostasis, notably through the anion transporter SLC26A6 (also known as putativeanion transporter1 or PAT1)in females. In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 checklist, a systematic search of online databases included Pubmed, ScienceDirect Journals, and Ingenta Connect Journals. Predetermined criteria to include and exclude papers, gathering articles published between 2012 and 2022, were determined. After a thorough analysis, eight articles (three cohorts, one case-control, one in vivo, one in vitro, and two cross-sectional studies) were identified for the final quality assessment review. The eight selected and quality-assessed articles provided evidence of a directly proportional connection between estrogen and kidneyfunction. Acorrelation between serum estrogen levels and the development of kidney stone disease was confirmed. Administration of β-estradiol was shown to effectively inhibit the function of the anion transporter PAT1 in a tissue-specific manner. In the case of the kidney, estrogen wasobserved to down-regulate PAT1, which led to a reduction in oxalate transporting activity and, consequently, a decrease in kidney stone formation. Consensus suggests that serum estrogen levels and optimal kidney functioning are interrelated. Furthermore,analysis of the quality-assessed articles and a comprehensive literature review revealed estrogen'stissue-specific regulation of the PAT1 anion transporter aids in maintaining kidney function and anion homeostasis.Additional research is needed to solidify estrogen's role in kidney stone disease to determine its therapeutic value in clinical practice.

A Novel Ion Species- and Ion Concentration-Dependent Anti-Counterfeiting Based on Ratiometric Fluorescence Sensing of CDs@MOF-Nanofibrous Films.

Traditional fluorescent anti-counterfeiting labels based on "on-off" fluorescence can be easily cloned. It is important to explore advanced anti-counterfeiting fluorescent labels with high-level security. Here, a pioneering ion species- and ion concentration-dependent anti-counterfeiting technique is developed. By successive loading Cu2+ -sensitive yellow emitted carbon dots (Y-CDs) and Cu2+ non-sensitive blue emitted carbon dots (B-CDs) into metal-organic frameworks (MOFs) and followed by electrospinning, the B&Y-CDs@MOF-nanofibrous films are prepared. The results show that the use of MOF not only avoids the fluorescence quenching of CDs but also improves the fluorescence stability. The fluorescence Cu2+ -sensitivity of the CDs@MOF-nanofibrous films can be regulated by polymer coating or lamination. The fluorescent label consisting of different Cu2+ -sensitivity films will show Cu2+ concentration-dependent decryption information. Only at a specific ion species and concentration (Cu2+ solution of 40-90µm), the true information can be read out. Less or more concentration (<40 or >90µm) will lead to false information. The identification of the real information depends on both the species and the concentration. After Cu2+ treatment, the fluorescence of the label can be recovered by ethylenediaminetetraacetic acid disodium (EDTA-2Na) for further recycling. This work will open up a new door for designing high-level fluorescent anti-counterfeiting labels.

Cascading effects of climate change and wildfire on a subarctic lake: A 20‐year case study of watershed change

AbstractMean annual air temperature has been increasing in Alaska since the 1970s and is expected to continue to increase through the current century, resulting in significant environmental changes (e.g., permafrost thaw, shifts in vegetation community composition and distribution, increased wildfire frequency and severity). Because there is little long‐term monitoring data available on lake ecosystems in the subarctic it is difficult to predict how lakes will respond. Here we present data from an ~20‐year long‐term lake and climate monitoring program in Interior Alaska. A significant portion of the lake catchment was burned by wildfires in 1986 and again in 2004. As a result, much of the vegetation in the lake catchment was converted from spruce‐dominated forest to deciduous forest, indicating likely permafrost degradation. At a nearby monitoring site absent of fire effects, mean annual ground temperatures at 50 and 90 cm warmed significantly from about −2°C to about −1°C over the 20‐year monitoring period. Warming of similar or greater magnitude is inferred at the study site due to fire effects. Lake water analyses before and after the 2004 fire show a significant postfire increase in dissolved organic carbon, total nitrogen, and total phosphorous that persisted for a short period (~3 years) and was followed by small, but significant, increases in specific conductance and ion concentrations. Approximately 15 years postfire sulfate and cation concentrations in the lake increased exponentially due to the development of a groundwater seep near the lake. The seep likely formed as a result of permafrost thaw creating new subsurface flowpaths in response to long‐term climate warming and fire effects. In 2021, specific conductance and sulfate concentrations reached 657 μS/cm and 71 mg/L respectively, exceeding tolerance thresholds of the water lily Nuphar lutea. In 2021, N. lutea beds that had occupied the lake since 1981 were no longer visible. Depending on local catchment characteristics, source waters and flow paths contributing to small subarctic lakes will continue to evolve uniquely in response to climate change and thawing permafrost. This case study shows the cascading effects of warming soil and wildfires on catchment characteristics as well as terrestrial and aquatic vegetation and lake water chemistry.

Application of the practical salinity scale to the waters of San Francisco estuary

The Practical Salinity Scale 1978 (PSS-78)—developed using samples of standard seawater—is widely used as a conductivity-based measure of salinity in oceans and estuaries. Here we evaluate the application of the scale across San Francisco Estuary where salinity reflects a mixture of seawater, riverine inflows, and agricultural return flows from islands within the estuary. We employ an extensive salinity data set that includes measurements of specific electrical conductance (EC) and major ion concentrations to demonstrate the scale's applicability in this estuary. We find the scale to be valid in waters dominated by seawater intrusion as well as in waters dominated by the largest riverine input to the estuary, i.e. the Sacramento River. In these waters, we further find that the scale to be valid well below its recommended lower-bound value of 2.0. However, the scale under-estimates salinity in waters dominated by the San Joaquin River, the second largest riverine input to the estuary. Similarly, the scale under-estimates salinity in agricultural return flows to the estuary. This work shows that a singular PSS-78 relationship cannot be used to accurately compute salinity across the entire estuary from EC measurements—a finding of considerable importance for salinity monitoring and modeling applications. Using data from the estuary, we propose appropriate corrections to the scale for these drainage-influenced waters. We recommend further research into how these modified PSS-78 formulations can be used to more accurately estimate salinity and ionic constituent concentrations in this and other estuaries.

Beyond the Primary Structure of Nucleic Acids: Potential Roles of Epigenetics and Noncanonical Structures in the Regulations of Plant Growth and Stress Responses.

Epigenetics deals with changes in gene expression that are not caused by modifications in the primary sequence of nucleic acids. These changes beyond primary structures of nucleic acids not only include DNA/RNA methylation, but also other reversible conversions, together with histone modifications or RNA interference. In addition, under particular conditions (such as specific ion concentrations or protein-induced stabilization), the right-handed double-stranded DNA helix (B-DNA) can form noncanonical structures commonly described as "non-B DNA" structures. These structures comprise, for example, cruciforms, i-motifs, triplexes, and G-quadruplexes. Their formation often leads to significant differences in replication and transcription rates. Noncanonical RNA structures have also been documented to play important roles in translation regulation and the biology of noncoding RNAs. In human and animal studies, the frequency and dynamics of noncanonical DNA and RNA structures are intensively investigated, especially in the field of cancer research and neurodegenerative diseases. In contrast, noncanonical DNA and RNA structures in plants have been on the fringes of interest for a long time and only a few studies deal with their formation, regulation, and physiological importance for plant stress responses. Herein, we present a review focused on the main fields of epigenetics in plants and their possible roles in stress responses and signaling, with special attention dedicated to noncanonical DNA and RNA structures.

Towards Selective Removal of Bromide from Drinking Water Resources using Electrochemical Desalination

Disinfection of drinking water is crucial in water treatment as it suppresses waterborne pathogenic diseases. However, as an unintended consequence, disinfection generates disinfection byproducts (DBP). DBPs are cytotoxic, carcinogenic, and nephrotoxic especially when they are brominated. Brominated DBP formation is governed by the interaction of reactive precursors such as natural organic matter (NOM), and Brˉ with oxidants that are added as disinfectants (e.g., chlorine, chloramines, ozone). Historically, the main strategy to control the formation of DBP was to remove NOM from water by coagulation, adsorption, bio-filtration, pre-oxidation, or membrane separation; however, processes that remove NOM do not necessarily remove Brˉ. Herein, we investigated the utilization of combined capacitive and faradaic ion removal in a flow cell to remove Brˉ as well as Clˉ concurrently with more selectivity towards the former. The effectiveness of the proposed technique was evaluated by determining the maximum salt adsorption capacity and measuring the specific ion concentration with ion chromatography. In a binary equimolar mixture of Brˉ and Clˉ, Brˉ was more selectively adsorbed over Clˉ at 1.2 V applied potential due to the contribution of bromine gas evolution to the capacitive deionization.

Geochemical benchmark tests to validate the conversion of thermodynamic data for TOUGHREACT

Abstract. According to the ongoing site selection process for a repository for high-level radioactive waste in Germany, rock salt, clay and crystalline rock are possible host rocks. The pore water of these rocks contains saline solutions with high ionic strengths. To model the speciation and/or migration of radionuclides in long-term safety analyses for nuclear waste disposal, a geochemical code that includes thermodynamic data suitable for saline solutions is needed. Thermodynamic equilibrium in saline solutions with high ionic strengths is usually modelled using the Pitzer approach (Pitzer, 1991). Within the context of nuclear waste disposal, the THEREDA project (Moog et al., 2015) provides thermodynamic data for some widely used geochemical codes (PHREEQC, Geochemist's Workbench, ChemApp, and EQ 3/6) using the Pitzer approach; however, for modelling in long-term safety analyses for nuclear waste disposal, another geochemical code, TOUGHREACT, is used. Therefore, scripts were developed to convert thermodynamic data of the THEREDA project to be applicable in TOUGHREACT. The scripts were validated by benchmark tests and by comparing calculations using PHREEQC and TOUGHREACT (Weyand et al., 2021). In total, 50 different benchmark tests were performed considering 3 specific geochemical systems, which are relevant to long-term safety analyses: (1) oceanic salt system, polythermal: K, Mg, Ca, Cl, SO4, H2O(l), (2) actinide system, isothermal: Am(III), Cm(III), Nd(III), Na, Mg, Ca, Cl, OH, H2O(l) and (3) carbonate system, isothermal: Na, K, Mg, Ca, Cl, SO4, HCO3/CO2(g), H2O(l). Each benchmark test considered specific ion concentrations in solution and in gaseous phases in the presence of specific minerals. The benchmark tests derived the geochemical equilibria and the results of both codes were compared to each other and to experimental data. The results of the calculations using both codes showed a good correlation. Remaining deviations can be explained by technical differences of the codes.

Influence of Surface Potential at Aqueous/TiO2 Thin-Film Interface on the Capacitance Performance

Electrochemical capacitors and capacitive deionization store energy through the interfacial layer formed between electrodes and electrolytes. TiO2 thin-film deposited on Si wafers was studied by ellipsometry under controlled humidity to explore the refractive index (dielectric constant) of pore water. The surface potential measured by electrophoretic mobility at different equilibrated pH and specific adsorbing ion concentrations influences the refractive index of pore water. The higher the surface potential, the higher the refractive index, the lowest refractive index occurring close to the isoelectric pH. The presence of the specific adsorbing ions on the nanopore walls increases the refractive index. Furthermore, galvanostatic charge/discharge measurements were performed using TiO2 thin films coated on platinized Ti coupons to obtain the capacitance of the aqueous TiO2 thin-film systems. The capacitance followed a similar trend as the surface potential and can be improved by specific adsorbing ion addition over the pH range of 5 to 9. In addition, the crystalline structure of TiO2 thin-film varied by different sintering temperatures also influences the surface potential, resulting a different capacitive performance. At elevated sintering temperature, TiO2 transfers from anatase to rutile with an increased surface potential. The electrochemical tests show that the electrode capacitance increases from 19.50 to 41.82 mF/cm2. The investigation of oxide materials in the application for electrochemical capacitors and capacitive deionization could be another possibility other than carbon materials.

Cells in New Light: Ion Concentration, Voltage, and Pressure Gradients across a Hydrogel Membrane.

The ionic compositions of the intra- and extracellular environments are distinct from one another, with K+ being the main cation in the cytosol and Na+ being the most abundant cation outside of the cell. Specific ions can permeate into and out of the cell at different rates, bringing about uneven distribution of charges and development of negative electric potential inside the cell. Each healthy cell must maintain a specific ion concentration gradient and voltage. To account for these functions, various ionic pumps and channels located within the cell membrane have been invoked. In this work, we use a porous alginate hydrogel as a model gelatinous network representing the plant cell wall or cytoskeleton of the animal cell. We show that the gel barrier is able to maintain a stable separation of ionic solutions of different ionic strengths and chemical compositions without any pumping activity. For the Na+/K+ concentration gradient sustained across the barrier, a negative electric potential develops within the K+-rich side. The situation is reminiscent of that in the cell. Furthermore, also the advective flow of water molecules across the gel barrier is restricted, despite the gel’s large pores and the osmotic or hydrostatic pressure gradients across it. This feature has important implications for osmoregulation. We propose a mechanism in which charge separation and electric fields developing across the permselective (gel) membrane prevent ion and bulk fluid flows ordinarily driven by chemical and pressure gradients.

Metal-Organic Framework Nanoparticles Induce Pyroptosis in Cells Controlled by the Extracellular pH.

Ion homeostasis is essential for cellular survival, and elevated concentrations of specific ions are used to start distinct forms of programmed cell death. However, investigating the influence of certain ions on cells in a controlled way has been hampered due to the tight regulation of ion import by cells. Here, it is shown that lipid-coated iron-based metal-organic framework nanoparticles are able to deliver and release high amounts of iron ions into cells. While high concentrations of iron often trigger ferroptosis, here, the released iron induces pyroptosis, a form of cell death involving the immune system. The iron release occurs only in slightly acidic extracellular environments restricting cell death to cells in acidic microenvironments and allowing for external control. The release mechanism is based on endocytosis facilitated by the lipid-coating followed by degradation of the nanoparticle in the lysosome via cysteine-mediated reduction, which is enhanced in slightly acidic extracellular environment. Thus, a new functionality of hybrid nanoparticles is demonstrated, which uses their nanoarchitecture to facilitate controlled ion delivery into cells. Based on the selectivity for acidic microenvironments, the described nanoparticles may also be used for immunotherapy: the nanoparticles may directly affect the primary tumor and the induced pyroptosis activates the immune system.

Spatial variability in specific discharge and streamwater chemistry during low flows: Results from snapshot sampling campaigns in eleven Swiss catchments

AbstractCatchments consist of distinct landforms that affect the storage and release of subsurface water. Certain landforms may be the main contributors to streamflow during extended dry periods, and these may vary for different catchments in a given region. We present a unique dataset from snapshot field campaigns during low‐flow conditions in 11 catchments across Switzerland to illustrate this. The catchments differed in size (10 to 110 km2), varied from predominantly agricultural lowlands to Alpine areas, and covered a range of physical characteristics. During each snapshot campaign, we jointly measured streamflow and collected water samples for the analysis of major ions and stable water isotopes. For every sampling location (basin), we determined several landscape characteristics from national geo‐datasets, including drainage area, elevation, slope, flowpath length, dominant land use, and geological and geomorphological characteristics, such as the lithology and fraction of quaternary deposits. The results demonstrate very large spatial variability in specific low‐flow discharge and water chemistry: Neighboring sampling locations could differ significantly in their specific discharge, isotopic composition, and ion concentrations, indicating that different sources contribute to streamflow during extended dry periods. However, none of the landscape characteristics that we analysed could explain the spatial variability in specific discharge or streamwater chemistry in multiple catchments. This suggests that local features determine the spatial differences in discharge and water chemistry during low‐flow conditions and that this variability cannot be assessed a priori from available geodata and statistical relations to landscape characteristics. The results furthermore suggest that measurements at the catchment outlet during low‐flow conditions do not reflect the heterogeneity of the different source areas in the catchment that contribute to streamflow.

Measuring Soluble Properties of Planetary Science Samples: Sensor and System Development Since the Wet Chemistry Laboratory

The measurement of the soluble properties (pH, eH, conductivity, specific ion concentrations, etc.) of planetary science samples provides important information on the habitability of a location, the bulk components of a sample, the potential for undesired effects on analysis protocols, and the history/preservation of the sample (e.g., geologic weathering, radiation processing, etc.). Electrochemical sensors are an ideal means to measure soluble properties because they excel at detecting ionic species in solution. The Wet Chemistry Lab (WCL) on the 2007 Mars Phoenix Lander was the first planetary science instrument to focus on soluble inorganic ion measurements and used an array of electrochemical sensors. WCL’s discovery of significant quantities of perchlorate salts in the Martian regolith helped reshape our understanding of Martian chemistry and the search for past or present life there. As NASA starts on a new chapter of exploration with potential missions to further out locations like the Ocean Worlds of Europa and Enceladus, it is a natural fit to adapt the successful WCL instrument for operation on bodies where the samples could be ice or liquid. Since the successful operation of WCL on Mars there have been a number of projects to improve sensor capabilities, develop microfluidic implementations, and prepare for Ocean World mission scenarios. This work has led to a number of developments, including: 1. Production of Ag/AgCl reference electrodes that are stable for use during flight missions. 2. Cyclic voltammetry methods for the specific detection of SO4 2- and NO3 -. 3. Adaptation of hydrogel-based ion-sensitive electrodes (ISEs) for use in microfluidic arrays. 4. The development of solid-contact ISEs for use during flight missions. 5. Radiation testing of ISE ionophores. 6. The development of microfluidic infrastructure based on successful small satellite payloads. The combination of all this work has led to a significant increase in sensor/system performance and robustness in preparation for potential missions to Ocean Worlds.

Investigation of zinc‑copper alloys as potential materials for craniomaxillofacial osteosynthesis implants.

In this study, zinc‑copper (ZnCu) alloys were investigated regarding their feasibility as absorbable metals for osteosynthesis implants, especially in the craniomaxillofacial area. Mechanical properties and in vitro corrosion behavior of as-rolled Zn-xCu (x = 1, 2 and 4 wt%) alloys were systematically evaluated and screened. The as-rolled Zn4Cu alloy had mechanical properties that were superior to the most absorbable craniomaxillofacial osteosynthesis materials recently reported. The addition of Cu to Zn showed to have no apparent effect on the corrosion rates of the samples. The rolling process on Zn and Zn1Cu resulted in more uniform corrosion than on as-cast counterparts after 28 days immersion. Furthermore, the Zn4Cu alloys exhibited no apparent cytotoxic effect towards L929, TAg or Saos-2 cells. Proliferation rates of TAg and Saos-2 cells were shown to be activated by specific Zn ion concentrations in the as-rolled Zn4Cu alloy extracts. Analysis of in vitro antibacterial properties revealed that the as-rolled Zn4Cu alloy possessed the potential to inhibit biofilm formation of mixed oral bacteria. We conclude that the as-rolled Zn4Cu alloy might be a promising material for fabrication of craniomaxillofacial osteosynthesis implants.

Preparation of self-propelled Cu-Pt micromotors and their application in miRNA monitoring

Self-propelled catalytic micromotors offer considerable promise in terms of many applications. Catalytic micromotors are strongly influenced by the presence and concentration of specific ions and chemicals in the environment, making them useful as sensors and actuators. In this work, copper (Cu)-platinum (Pt) micromotors were fabricated by using the magnetron sputtering method for the first time in the literature and their applications based on the detection of miRNA-21 were evaluated. We analyzed the dependence of the mobility of Cu-Pt micromotors using different concentrations of hydrogen peroxide (H$_{2}$O$_{2})$. The presence of surfactants in the environment is also important for the movement of the micromotors. Thus, we studied the effect of three different surfactants: anionic as sodium dodecyl sulfate (SDS), cationic as cetyltrimethylammonium bromide (CTAB), and nonionic as Triton X-100. Cu-Pt micromotor motion was observed even at very low concentrations of surfactant (0.01%) and hydrogen peroxide (0.25%). miRNAs have been regarded as biomarker candidates in early diagnosis. Our sensing strategy relied on dye-labeled single-stranded DNA immobilization onto Cu-Pt micromotors that recognize the target miRNA-21. The changes in the fluorescence intensity as well as the changes in the speed of micromotors were examined before and after hybridization.

Regulations are needed to protect freshwater ecosystems from salinization.

Anthropogenic activities such as mining, agriculture and industrial wastes have increased the rate of salinization of freshwater ecosystems around the world. Despite the known and probable consequences of freshwater salinization, few consequential regulatory standards and management procedures exist. Current regulations are generally inadequate because they are regionally inconsistent, lack legal consequences and have few ion-specific standards. The lack of ion-specific standards is problematic, because each anthropogenic source of freshwater salinization is associated with a distinct set of ions that can present unique social and economic costs. Additionally, the environmental and toxicological consequences of freshwater salinization are often dependent on the occurrence, concentration and ratios of specific ions. Therefore, to protect fresh waters from continued salinization, discrete, ion-specific management and regulatory strategies should be considered for each source of freshwater salinization, using data from standardized, ion-specific monitoring practices. To develop comprehensive monitoring, regulatory, and management guidelines, we recommend the use of co-adaptive, multi-stakeholder approaches that balance environmental, social, and economic costs and benefits associated with freshwater salinization.This article is part of the theme issue 'Salt in freshwaters: causes, ecological consequences and future prospects'.

Assessing the Potential of Nontraditional Water Sources for Landscape Irrigation

Scarcity and competition for good quality and potable water resources are limiting their use for urban landscape irrigation, with several nontraditional sources being potentially available for these activities. Some of these alternative sources include rainwater, stormwater, brackish aquifer water, municipal reclaimed water (MRW), air-conditioning (A/C) condensates, and residential graywater. Knowledge on their inherent chemical profile and properties, and associated regional and temporal variability, is needed to assess their irrigation quality and potential short- and long-term effects on landscape plants and soils and to implement best management practices that successfully deal with their quality issues. The primary challenges with the use of these sources are largely associated with high concentrations of total salts and undesirable specific ions [sodium (Na), chloride (Cl), boron (B), and bicarbonate (HCO3−) alkalinity]. Although the impact of these alternative water sources has been largely devoted to human health, plant growth and aesthetic quality, and soil physicochemical properties, there is emergent interest in evaluating their effects on soil biological properties and in natural ecosystems neighboring the urban areas where they are applied.

Performance regulation of Mn/TiO2 catalysts by surfactants for the selective catalytic reduction of NO with NH3 at low temperatures

A series of Mn/TiO2 catalysts were prepared using different dosage of cetyl trimethyl ammonium bromide (CTAB) and polyethylene glycol (PEG) 600 as surfactants by sol–gel method. When CTAB/Ti and PEG/Ti were 0.075 and 0.13, the morphology of the catalysts exhibited nano rod and regular sphere structure, respectively, and the activity was also the highest. The superior SCR activity of NC(0.075)-Mn/TiO2 and NP(0.13)-Mn/TiO2 catalysts was mainly due to the larger surface area and stronger reduction ability. In addition, it was found that the SCR activity of the catalysts with PEG600 as surfactants was generally higher than that of CTAB as surfactants, which may be due to its advantages in specific surface area, crystallinity, acidity, surface ion and chemisorbed oxygen concentration, and reducibility.