Source Of Ions Research Articles

Preparation of 3D printable polyvinyl alcohol based conductive hydrogels via incorporating k-carrageenan for flexible strain sensors

Advances in conductive hydrogels are responding to the emerging need for flexible strain sensors. However, achieving an excellent combination of injectability, conductivity, and sensing characteristics is challenging. For this purpose, suitable 3D printing inks are required to generate hydrogels with the desired morphological and functional characteristics. We composited thermosensitive kC with PVA using borax as a cross-linking agent and a source of conductive ions (Na+) to obtain borax cross-linked PVA and kC conductive hydrogel inks. And then, the corresponding conductive hydrogels (B-PVA/kC) were successfully prepared using their thermal response behavior and freeze-thaw method. The results show that kC enables B-PVA/kC to undergo a rapid sol-gel transition when cooled from 70 °C to room temperature. The B-PVA/kC hydrogels show a fast, sensitive, and accurate response to movement. After a freeze-thaw cycle (1 F-T), the hydrogels still have good electrical conductivity and strain-sensing properties, with better strength and increased structural stability. More excitingly, this hydrogel can be printed in different shapes to fit the body better and also exhibits good sensing signals when compressed by external forces, which is expected to facilitate the personalization of flexible strain sensors.

Effects of Adding Chitosan on Drug Entrapment Efficiency and Release Duration for Paclitaxel-Loaded Hydroxyapatite-Gelatin Composite Microspheres.

Hydroxyapatite-gelatin microspheres with cone-like pores were synthesized via the wet-chemical method using ammonium dihydrogen phosphate ((NH4)H2PO4) and calcium nitrate (Ca(NO3)2·4H2O) as a source of calcium and phosphate ions with the addition of gelatin, which proved to be more osteoconductive than commercial products, such as fibrin glue and Osteoset® Bone Graft Substitute. Following the method of the previous study for loading paclitaxel (PTX), a drug entrapment efficiency of around 58% was achieved, which is much lower than that of the doxorubicin (DOX)-loaded one. Since PTX is hydrophobic while DOX is hydrophilic, the order of chitosan processing and addition of the solvent were tuned in this study, finally leading to an increase in drug entrapment efficiency of 94%. Additionally, the release duration of PTX exceeded six months. The MTT assay indicated that the effect of drug release on the suppression of cancer cells reached more than 40% after one week, thereby showcasing PTX's capacity to carry out its medicinal functions without being affected by the loading procedures.

Process of preparing chloride-free KNS compound fertilizers from phosphogypsum waste using a quaternary phase diagram

Phosphogypsum (PG), commonly known as calcium sulfate, is a waste by-product generated during the production of phosphoric acid by the wet phosphoric acid process (WPA). It is well known that every year the phosphate industries produce a large quantity of PG around the world (i.e., Currently, global production of this waste is estimated at 300 Mt/ year), but the valorization processes of this waste are limited and low valuable. In this study, we investigated the recycling of PG by-product, which can be considered very promising sources of sulfate ions (SO42-) for the manufacturing of chloride-free KNS compound fertilizer based on potassium-ammonium sulfate ([K1−x(NH4)x]2SO4). The primary objective of this study was to develop a methodology for [K1−x(NH4)x]2SO4 synthesis and its separation process using the quaternary phase diagram K+, NH4+ / Cl-, SO42- - H2O at 25 °C. The experiment results show that it is possible to recover relatively pure (NH4)2SO4 from PG to re‐synthesize in presence of KCl the [K1−x(NH4)x]2SO4 phase, whose high quality and purity were confirmed by the combined use of several analytical and characterization techniques such as X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), and gamma spectrometry analysis. The thermal decomposition was supplemented by Thermo-Gravimetric Analysis (TGA) coupled with Differential Thermal Analysis (DTA). The main findings of this study may assist in developing methods for valorizing PG waste by converting it into valuable fertilizer products, which are particularly suitable for cultivating chloride-sensitive crops. Thus, total or partial substitution of non-renewable resources by PG not only helps to solve the environmental pollution caused by this waste, but also reduces production costs and improves farm economics.

Effects of Cr Concentration on the Morphology and Corrosion Resistance of Ni-Cr Coatings Prepared by the Electrodeposition Process on 25CrMo4 Steel

In the current study, Ni-Cr coatings with a various Cr concentrations from 0.1% Cr (up to 0.4 % Cr) were performed on the 25CrMo4 low steel, using the electrodeposition process. The deposition of the Ni-Cr coatings was carried out at temperature of 30°C , direct current density of 2 A/dm2 for 40 min , and a bath containing a Cr2(SO4)3 as source of chromium ions , Cr+. However, the effects of the Cr concentration on the morphology and the quality of the film were investigated. SEM, EDS and XRD analysis were used in order to characterize the Ni-Cr coatings. The SEM morphology analysis exhibited that the Ni-Cr with 0.2% Cr showed the lowest network of cracks and porosity with uniform and compact structure. The corrosion resistance of the Ni-Cr coatings has been investigated in 3.5 wt-% NaCl aqueous solution, using polarization curves and electrochemical impedance spectroscopy. According to the results, it was found that the variation of Cr content in the Ni-Cr coatings greatly affected the microstructure and the corrosion resistance of the coatings. Moreover, the coating developed with 0.2 % of chromium (Cr) can give excellent results as to quality , morphology and corrosion resistance in 3.5 wt-% NaCl environment.

Silica-Containing Biomimetic Composites Based on Sea Urchin Skeleton and Polycalcium Organyl Silsesquioxane.

The paper presents an original approach to the synthesis of polycalciumorganyl silsesquioxanes through the reaction of polyorganyl silsesquioxanes [RSiO1.5]n (where R is an ethyl and phenyl radical) with sea urchin skeleton under the conditions of mechanochemical activation. The novelty and practical significance of the present study lies in the use of an available natural raw source as a source of calcium ions to initiate the reaction of calcium silicate formation and create a matrix for the formation of a porous inorganic composite framework. The thermal stability of the introduced silicates, i.e., the ability to maintain a porous structure at high temperatures, is key to the production of an ordered porous material. The reaction scheme was proposed to be based on the interaction of calcium carbonate with the siloxane bond. FTIR, XRD, GPC, and TGA were used to study the composition and structure of the obtained materials. The cross-sectional area of the polymer chain and the volumes of the coherent scattering regions of the polymers obtained were calculated from the XRD data. To prepare the composites, the sea urchin skeleton was further modified with polycalciumorganyl silsesquioxanes in a toluene solution. To remove the sea urchin skeleton, the obtained biomimetic composites were treated with hydrochloric acid. The results of the morphological and surface composition studies are reported. The method proposed in the paper could be of fundamental importance for the possibility of obtaining structured porous composite materials for a wide range of practical applications, including for the purpose of creating a composite that may be a promising carrier for targeted delivery of chemotherapy agents.

3D printing of PCL-ceramic composite scaffolds for bone tissue engineering applications

Three-dimensional (3D) printing was utilized for the fabrication of a composite scaffold of poly(ε-caprolactone) (PCL) and calcium magnesium phosphate (CMP) bioceramics for bone tissue engineering application. Four groups of scaffolds, that is, PMC-0, PMC-5, PMC-10, and PMC-15, were fabricated using a custom 3D printer. Rheology analysis, surface morphology, and wettability of the scaffolds were characterized. The PMC-0 scaffolds displayed a smoother surface texture and an increase in the ceramic content of the composite scaffolds exhibited a rougher structure. The hydrophilicity of the composite scaffold was significantly enhanced compared to the control PMC-0. The effect of ceramic content on the bioactivity of fibroblast NIH/3T3 cells in the composite scaffold was investigated. Cell viability and toxicity studies were evaluated by comparing results from lactate dehydrogenase (LDH) and Alamar Blue (AB) colorimetric assays, respectively. The live-dead cell assay illustrated the biocompatibility of the tested samples with more than 100% of live cells on day 3 compared to the control one. The LDH release indicated that the composite scaffolds improved cell attachment and proliferation. In this research, the fabrication of a customized composite 3D scaffold not only mimics the rough textured architecture, porosity, and chemical composition of natural bone tissue matrices but also serves as a source for soluble ions of calcium and magnesium that are favorable for bone cells to grow. These 3D-printed scaffolds thus provide a desirable microenvironment to facilitate biomineralization and could be a new effective approach for preparing constructs suitable for bone tissue engineering.

The Computational Acid-Base Chemistry of Hepatic Ketoacidosis.

Opposing evidence exists for the source of the hydrogen ions (H+) during ketoacidosis. Organic and computational chemistry using dissociation constants and alpha equations for all pertinent ionizable metabolites were used to (1) document the atomic changes in the chemical reactions of ketogenesis and ketolysis and (2) identify the sources and quantify added fractional (~) H+ exchange (~H+e). All computations were performed for pH conditions spanning from 6.0 to 7.6. Summation of the ~H+e for given pH conditions for all substrates and products of each reaction of ketogenesis and ketolysis resulted in net reaction and pathway ~H+e coefficients, where negative revealed ~H+ release and positive revealed ~H+ uptake. Results revealed that for the liver (pH = 7.0), the net ~H+e for the reactions of ketogenesis ending in each of acetoacetate (AcAc), β-hydroxybutyrate (β-HB), and acetone were -0.9990, 0.0026, and 0.0000, respectively. During ketogenesis, ~H+ release was only evident for HMG CoA production, which is caused by hydrolysis and not ~H+ dissociation. Nevertheless, there is a net ~H+ release during ketogenesis, though this diminishes with greater proportionality of acetone production. For reactions of ketolysis in muscle (pH = 7.1) and brain (pH = 7.2), net ~H+ coefficients for β-HB and AcAc oxidation were -0.9649 and 0.0363 (muscle), and -0.9719 and 0.0291 (brain), respectively. The larger ~H+ release values for β-HB oxidation result from covalent ~H+ release during the oxidation-reduction. For combined ketogenesis and ketolysis, which would be the metabolic condition in vivo, the net ~H+ coefficient depends once again on the proportionality of the final ketone body product. For ketone body production in the liver, transference to blood, and oxidation in the brain and muscle for a ratio of 0.6:0.2:0.2 for β-HB:AcAc:acetone, the net ~H+e coefficients for liver ketogenesis, blood transfer, brain ketolysis, and net total (ketosis) equate to -0.1983, -0.0003, -0.2872, and -0.4858, respectively. The traditional theory of ketone bodies being metabolic acids causing systemic acidosis is incorrect. Summation of ketogenesis and ketolysis yield H+ coefficients that differ depending on the proportionality of ketone body production, though, in general, there is a small net H+ release during ketosis. Products formed during ketogenesis (HMG-CoA, acetoacetate, β-hydroxybutyrate) are created as negatively charged bases, not acids, and the final ketone body, acetone, does not have pH-dependent ionizable groups. Proton release or uptake during ketogenesis and ketolysis are predominantly caused by covalent modification, not acid dissociation/association. Ketosis (ketogenesis and ketolysis) results in a net fractional H+ release. The extent of this release is dependent on the final proportionality between acetoacetate, β-hydroxybutyrate, and acetone.

Bromamine-T (TsNBrNa): A Biologically Significant, Versatile Bromo-Organic Reagent

AbstractBromamine-T (BAT) is a notable member of a special class of compounds called organic haloamines, which are oxidising agents. It can act as the source of halonium ions, hypohalite species, and N-anions, whilst also displaying basic and nucleophilic properties. Bromamine-T finds wide application as an efficient reagent for various organic transformations, such as aminobromination, amination, oxidation, and others. It can be used under mild conditions and has low toxicity. Moreover, due to its immense biological significance, this reagent is piquing the interest of many researchers.1 Introduction1.1 The Sodium Salt of N-Bromo-p-toluenesulfonamide (Bromamine-T or TsNBrNa): Reagent Overview1.2 Physical Properties of Bromamine-T1.3 Preparation and Characterisation of Bromamine-T2 Biological Significance of Bromamine-T3 Organic Transformations Using Bromamine-T3.1 Aminobromination3.2 Amination3.3 Aminohydroxylation3.4 Aziridination3.5 Bromination3.6 Oxidation: Kinetic and Mechanistic Studies4 Conclusion

Chemical weathering of small watersheds in the upper reaches of Jinsha river on the eastern edge of the Qinghai–Tibet Plateau

Land chemical weathering is a crucial and common geological process on the Earth’s surface. Studying the surface chemical weathering process in basins is important to the net consumption rate of atmospheric CO2, climate change in geological history, and the global carbon cycle. In this study, a small watershed in the upper reaches of Jinsha River on the eastern edge of the Qinghai-Tibet Plateau is selected as the study area. By measuring the physical and chemical properties and the main ion content of the water in the watershed and by using the factor analysis method, the source of the main ion components in the water in the alpine basin and the characteristics of the chemical weathering of the basin rocks are examined. Results show that the pH value of surface water in the study area varies from 7.4 to 8.2, and the overall performance is moderately to weakly alkaline. The total salinity in the basin is between 52.42 and 398.19 mg/L, with an average value of 180.06 mg/L. The concentration of main cations in surface water follows the order Ca2+>Mg2+>Na+>K+. The concentration relationship of the main anions is in the order HCO3−>SO42−>Cl−, and the hydrochemical type is HCO3_Ca. The main source of ions in the study area is rock weathering, which is controlled by the chemical weathering of carbonate rocks. The contribution rates of carbonate (mainly dolomite and calcite dissolution), evaporite, and silicate to the dissolved matter in the river are 59.40%, 7.30%, and 3.00% respectively, and the contribution rate of CO2 in the atmosphere to the dissolved matter in the river is 30.30%. The total chemical weathering rate in the study area is 29.09 t/km2 ⋅a, which is at a low level, indicating that weak hydrothermal conditions slow down the chemical weathering process of rock minerals.

Converting Iron Corrosion Product to Nanostructured Conducting Polymers: Synthetic Strategies and Applications

ConspectusIron corrosion product, commonly known as rust, forms from the chemical reaction between iron and oxygen in the presence of water. It is a heterogeneous solid-state material composed of multiple phases and is ubiquitous throughout the universe. Sixteen distinct phases of iron corrosion product exist naturally under different temperature, pH, and pressure. Rust species such as hematite (α- Fe2O3), maghemite (γ-Fe2O3), goethite (α-FeOOH), and lepidocrocite (γ- FeOOH), first documented ca. 800 BCE, make up the solid-state chemical family composed of iron oxides, oxyhydroxides, and hydroxides. On an anthropogenic scale, rust represents a persistent problem to all manner of engineering and industrial pursuits. Corrosion is gradual and nondiscriminatory, affecting iron structures of all shapes and sizes from bridges and buildings to pipelines and wires that necessitates considerable spending on rust prevention and removal techniques. The infamous “Rust Belt” is colloquially used to describe regions of the United States characterized by sharp industrial decline and evokes images of derelict steel factories rusted over from decades of disuse. Therefore, iron corrosion product is commonly regarded as a symptom of deterioration and a physical manifestation of neglect in the eyes of the public. Yet, invaluable scientific potential exists within this “waste” material.Rust is thermodynamically stable, inexpensive, easily processable, and an abundant source of ferric ions (Fe3+) and therefore serves as an attractive oxidative candidate for developing chemical reactions. The ferric ion, with a standard reduction potential of +0.77 V, is an oxidizing agent that is well-investigated in the syntheses of highly conductive conjugated polymers such as poly(3,4-ethylenedioxythiophene) (PEDOT) and polypyrrole (PPy). Additionally, hydrolysis products of ferric ions form various nanostructures and provide diversified growing template for conducting polymers, including rod-shape akageneite (β-FeOOH), fiber-shape goethite (α-FeOOH), 2D sheet iron oxychloride (FeOCl), and spherical/cubic hematite (α-Fe2O3).In this Account, we introduce our unique synthetic strategies that involve rust and advance the state-of-the-art in chemical synthesis of nanostructured conducting polymers. We utilize products from rust, droplets with rust, and interfaces containing rust to synthesize nanostructured conducting polymer including rust-based vapor-phase polymerization (RVPP), aerosol vapor polymerization (AVP), and condensing vapor-phase polymerization (CVPP). Owing to the high conductivity and high surface area, nanostructured conducting polymers are emerging as hotspots for electrode materials in energy storage devices (i.e., supercapacitors) and solar cells. In the second part of this Account, we discuss how combining our unique synthetic strategies with conventional materials and fabrication techniques produces devices with high figure of merit performance. These devices include a brick supercapacitor as proof-of-concept energy storage masonry material, a 3D microsupercapacitor with a superior and low-cost electrode engineering strategy as well as high energy density larger than a thin-lithium battery, and a dye-sensitized solar cell with an efficiency superior to that of Pt with cost-effective fabrication.

Phenol removal by electro-Fenton process using a 3D electrode with iron foam as particles and carbon fibre modified with graphene

The 3D electro-Fenton technique is, due to its high efficiency, one of the technologies suggested to eliminate organic pollutants in wastewater. The type of particle electrode used in the 3D electro-Fenton process is one of the most crucial variables because of its effect on the formation of reactive species and the source of iron ions. The electrolytic cell in the current study consisted of graphite as an anode, carbon fiber (CF) modified with graphene as a cathode, and iron foam particles as a third electrode. A response surface methodology (RSM) approach was used to optimize the 3D electro-Fenton process. The RSM results revealed that the quadratic model has a high R2 of 99.05 %. At 4 g L-1 iron foam particles, time of 5 h, and 1 g of graphene, the maximum efficiency of phenol removal of 92.58 % and chemical oxygen demand (COD) of 89.33 % were achieved with 32.976 kWh kg-1 phenol of consumed power. Based on the analysis of variance (ANOVA) results, the time has the highest impact on phenol removal efficiency, followed by iron foam and graphene dosage. In the present study, the 3D electro-Fenton technique with iron foam partials and carbon fiber modified with graphene was detected as a great choice for removing phenol from aqueous solutions due to its high efficiency, formation of highly reactive species, with excellent iron ions source electrode.

Oxidation Kinetics of some Unsaturated Acids by Tributylammonium Chlorochromate: A mechanistic Study

The oxidation of maleic, fumaric, crotonic and cinnamic acids by tributylammonium chlorochromate (TBACC) in dimethylsulphoxide (DMSO) leads to the formation of corresponding epoxide. The reaction is of first order with respect to TBACC. A Michaelis-Menten type of kinetics are observed w.r.t. the acids. Due to non-aqueous nature of the solvents, toluene-p-sulphonic acid (TsOH) was used as the source of hydrogen ions. The reaction is catalysed by hydrogen ions. The hydrogen-ion dependence has the form: kobs = a + b [H+]. The oxidation of these acids was studied in nineteen different organic solvents. The solvent effect was analyzed by Kamlet’s and Swain’s multiparametric equations. Solvent effect indicated the importance of the cation-solvating power of the solvent. A mechanism involving a three-centre transition state has been postulated.

Photocatalytic Decolourization of Rhodamine B by Modified Photo-Fenton Process with Quasicrystals – Preliminary Research

Abstract A novel photocatalytic process using a modification of photo-Fenton reaction, with sodium percarbonate (SP), as an alternative source of H2O2, and alloy Al65Cu20Fe15 containing, among others, quasicrystals (of the percentage composition Al65Cu20Fe15), being a source of iron ions, effectively decolourizes the aqueous solution of rhodamine B (RB; solution of 5 mg/l). The source of UV radiation was a lamp with a power of 36 W. The experiments were carried out at pH = 7 and reaction time (from 5 to 60 min). The increase in SP concentration (in the range of 8.3 to 33.3 g/l) significantly increased the degree of degradation of RB and the reaction rate. However, the use of quasicrystals, in the range of 8.3 to 33.3 g/l, was also important in the modified photocatalytic photo-Fenton process. The best degradation effects of RB (95%) were obtained for the highest SP concentration of 33.3 g/l and the lowest quasicrystal concentration of 8.3 g/l. On the other hand, visual decolourization of RB was obtained with an efficiency of 70% for SP and quasicrystal concentrations of 16.7 g/l and 16.7 g/l, respectively, after 45 minutes, and for SP and quasicrystal concentrations of 33.3 g/l and 8.3 g/l, respectively, after the time of 20 minutes. The best RB degradation effects in the comparative method (UV/Na2CO3·1.5H2O2 without the addition of quasicrystals) were only 52.7%. The obtained results encourage further research to optimize the conditions of the proposed method and to investigate its applicability to other types of dyes and pollutants.

Characterisation and Source Identification of Inorganic Water-Soluble Ions in PM2.5 in a Small-Size Steel City of China

Ambient PM2.5 samples were collected in Laiwu, a small industrial city in China known for steel production, to measure and evaluate the mass concentrations of PM2.5 and the inorganic water-soluble ions (IWS ions). The highest PM2.5 value recorded was 251.28 μg/m3, which occurred during winter and was lower than other major Chinese cities. The spatial distribution showed that the center of the city, which is connected to the downtown area, was heavily polluted (170 μg/m3 higher) compared to the suburbs. With the exception of winter, the weight of PM2.5 was dominated by IWS ions, with three secondary ions (NO3 -, SO4 2-, and NH4 +) accounting for more than 70% of the total ions in mass. This percentage is higher than that of big cities. An increase in sulfur oxidation ratios (SOR), nitrogen oxidation rate (NOR), and anion equivalent/cation equivalent (AE/CE) indicated that the atmosphere in Laiwu was more oxidized than other big cities. The ion analysis revealed that PM2.5 was highly correlated with NO3 -, SO4 2-, and NH4 +. The principal component analysis indicated that district heating during winter and industrial output and secondary transformation during summer were the major sources of the water-soluble ions. The backward trajectory study identified the north of Shandong Province as the likely source-area that affected air quality in Laiwu.

Facile synthesis of electrospun antibacterial bioactive glass based micronanofibre (ABGmnf) for exalted wound healing: In vitro and in vivo studies

Recently, bioactive glass has shown an incredible potential to address the assortment of chronic wounds including diabetic and venous ulcers. In this regard, the textural properties of bioactive glass (BG)-based micronanofibre, which are analogous to the fibrin clot that aggregates platelets, provide advantages that support the coagulation cascade and subsequent soft tissue regeneration by providing mechanical support and a source of various therapeutic ions. In this correspondence, we synthesized a binary composition comprising (70-x) mol% SiO2, (30-y) mol% CaO, 1 < x < 5 mol% B2O3 and 0.001< y < 0.1mol% Ag2O composition (ABGmnf) via sol-gel method followed by fabrication of the electrospun fibres, and state-of-art characterizations, XRD, FTIR, and FESEM-EDXalong with biological studies including in-vitro cytocompatibility, 2D wound healing, antibacterial activities by determination of minimum inhibitory concentration (MIC). In addition, the concentration of proinflammatory cytokines (TNF-α and IL-6) and various hematological, biochemical, and histopathological parameters were used to establish the in vivo biocompatibility. The in vivo wound healing assay, which demonstrated rapid wound closure, was then examined. ABGmnf's excellent cyto- and biocompatibility could be demonstrated by the above findings alongwith the lack of host-material interaction, as well.

Linking Snow, Soil, and Stream During Snowmelt and Rain‐On‐Snow Events: Storage and Transport of Ions in an Acid‐Sensitive Alpine Catchment (Tatra Mountains, Poland)

AbstractThe purpose of the study was to examine the storage and transport of ions through snowpack, soils, and stream water in an acid‐sensitive alpine catchment (Tatra Mountains, Poland) during snowmelt and rain‐on‐snow events. Samples of snowpack layers, near‐surface soil horizons, and stream water were collected in the winter and snowmelt seasons of 2019. A laboratory experiment was conducted to determine the effect of temperature on the rate of soil nitrogen mineralization and nitrification. Our study has shown that snowpack is an important source of ions in the catchment. As the snow melts, the release of ions from snowpack occurs. A gradual and slow melting of snow starts even before the first snowmelt‐induced increase in stream discharge. ions eluted from available snowpack are temporarily stored in soil, which is shown by a large increase in the concentration of water‐soluble in the soil at that time. ions are washed out of soils and supplied to streams during the first snowmelt event. This is demonstrated by a large increase in the stream water concentration, termed an “ pulse.” The ion is a key acid anion responsible for the acidification of the studied stream during snowmelt season, as the pulse coincides with a decrease in bicarbonate alkalinity. Our field research and laboratory experiment have shown a minor role of mineralization and nitrification in production in soils in the winter and pulse formation in stream water during the early stages of the snowmelt season.

Characteristics and Causes of Coastal Water Chemistry in Qionghai City, China

The coastal zone area of Qionghai City is one of the important coastal zones in the South China Sea, and its water environment has been affected by human activities such as urbanization and industrialization. In order to protect the water resources and ecological environment of this area, the water chemistry characteristics of the main watersheds and their causes in the coastal zone area of eastern Hainan Island were investigated to provide a scientific basis for environmental protection and sustainable development. In this study, the characteristics and sources of water chemical ion components were analyzed using a Piper trilinear diagram, Gibbs diagram, and correlation analysis with the coastal zone area of Qionghai city as the research object. The results show the following: (1) the dominant cation of water chemistry in the coastal zone of Qionghai City is Na+ with a mean value of 35.001 mg·L−1, and the dominant anion is Cl− with a mean value of 30.69 mg·L−1; (2) the dominant cation content in the coastal zone of Qionghai City is Na+ &gt; Ca2+ &gt; Mg2+ &gt; K+, and the dominant anion content is Cl− &gt; SO42− &gt; HCO3− &gt; CO32−; (3) at the five collection sites in the study area, the ion concentrations showed different trends, with the highest ion concentration in the water samples collected from aquaculture ponds, and the main water chemistry type was Na-Cl; the lowest ion concentration was in the water samples collected from the rivers, and the main type of water chemistry was Ca·Mg-HCO3. The source of water chemistry ions in the study area mainly included seawater, rock weathering, atmospheric precipitation, and evaporation concentration. The results of this study can provide a scientific basis for the development, utilization, and management of local water resources and provide basic data for environmental protection and sustainable development.

Hydrochemical characteristics of groundwater in a plain river network region: Establishing linkages between source and water quality variables

The chemical characteristics of groundwater can indicate water quality condition and provide useful information for pollution source identification. This study aimed to understand the effects of dissolved organic matter (DOM) on ionic composition of groundwater and identify the main ions and sources of pollution. The Lake Taihu is a typical eutrophic lake in China. In this study, the hydrochemical composition of groundwater in the surrounding aquifer of Lake Taihu Basin was analyzed. The results showed that the values of water quality index (WQI) range from 13.29 to 56.26 (good water quality). The dominant hydrochemical type of groundwater was Ca–Mg–HCO3 type, and the rock dominance was the major mechanism controlling the groundwater chemistry. With an increasing concentration in dissolved organic carbon (DOC), the Na+, Mg2+, and HCO3– concentrations all showed a sharp increase followed by a slow increase, while the NO3– concentration showed an opposite trend, indicating the DOM can affect the ions composition. In addition, K+ was positively correlated with NO3–, As, and Cd. Hence, DOM input may directly or indirectly change the hydrochemistry of groundwater. Besides, the NO3– concentration in groundwater was much higher than that in Lake Taihu, indicating that the NO3– in groundwater mainly came from surface soil leaching. The anthropogenic sources are probably the main sources of different ions, including K+, NO3–, As, and Cd. This study can help to better understand the effects of lake eutrophication on groundwater and its pathways.

Sulfate in streams and groundwater in a cold region (Yukon Territory, Canada): Evidence of weathering processes in a changing climate

Analyses of the sulfur (S) and oxygen (O) stable isotope ratios (δ34SSO4 and δ18OSO4) of dissolved sulfate in streams and groundwater in Yukon Territory (YT, Canada) indicates that the dominant source of this major ion is oxidation of sulfide minerals. In these streams, sulfate has a large range in δ34SSO4 values (−19 to +10‰), which is consistent with the lower portion of the documented range for δ34S of sulfides in bedrock in YT (∼ −35 to +55‰). Furthermore, the large majority of the δ18OSO4 data plot within the expected field for sulfide oxidation in cross-plots of δ18OSO4 versus the O isotope ratios of ambient water (δ18OH2O). δ18OSO4 values plotting above that field were likely affected by microbial sulfate reduction, a process that enriches residual sulfate in both 34S and 18O. The stable isotope data indicate that dissolution of marine-evaporite gypsum, which has higher δ34SSO4 and δ18OSO4 values compared to all stream and groundwater samples, is a minor to negligible source of sulfate in the YT streams. Association of sulfate with other solutes indicates release of various metals from sulfide minerals, and suggests dominance of silicate weathering in response to oxidation of the sulfides. Variations in sulfate concentrations in YT streams are largely related to geology, while terrain and climate, including extent of permafrost, are also important factors. Long-term monitoring of sulfate concentrations in YT streams indicates increasing concentrations over time, in both streams impacted by mining, and in streams that have not been affected much by historical in-catchment industrial activities. Increases were largest in streams in northern and central-south YT in the presence of thawing continuous to discontinuous permafrost.

Application of source-sink theory and MCR model to assess hydrochemical change risk in Lhasa River basin, Tibet, China

The Lhasa River, one of the tributaries of the Yarlung Zangbo River on the Tibetan Plateau, provides water for the vast majority of residents in Tibet. The main purpose of this study is to identify regional environmental risk factors that may be affecting the Lhasa River basin. The minimum cumulative resistance (MCR) model was used to determine the “source-sink” risk pattern of the Lhasa River by identifying the sources of metal ions and trace elements in the basin. The results show that loss of soil ions, climate conditions and environmental factors contribute to the hydrochemical characteristics of the Lhasa River basin. The distribution of soil type greatly overlaps with the likelihood of soil ions loss. The low-risk and high-risk zones mainly consist of calcic soils and litho soils, respectively. In terms of the climate and environmental risk factors, rainfall erosivity poses the greatest risk during the low-flow season, vegetation coverage during the high-flow season, and freeze-thaw erosivity during the normal-flow season. High-risk sources and low-risk sources were identified by the MCR model. The high-risk sources were the vegetated and unused lands, which are vulnerable to weathering of Ca and Mg rich sedimentary and mixed rocks, while low-risk sources were the urban, construction, industrial and mining areas and forest land. This study can contribute to the development of policies for the sustainable management of water resources and the protection of the water environment in the Lhasa River Basin.