Influence Of Water Chemistry Research Articles

The efficacy of Pb, As(v) and Sb(iii) removal by biochar is determined by solution chemistry

A design of experiments approach was used to elucidate the combined effects of dissolved ions and particulate phases on the efficacy of biochar in metal and metalloid removal.

Chemical Corrosion-Water-Confining Pressure Coupling Damage Constitutive Model of Rock Based on the SMP Strength Criterion.

Aiming at the problem of chemical-mechanics-hydro (C-M-H) action encountered by rocks in underground engineering, chemical damage variables, water damage variables, and force damage variables are introduced to define the degree of degradation of rock materials. Stone is selected as the sample for acid corrosion treatment at pH 3, 4, and 7, and a chemical damage factor is defined that coupled the pH value and duration of exposure. Then based on the spatial mobilized plane (SMP) criterion and the Lemaitre strain equivalence hypothesis, this research develops a constitutive model considering rock chemical corrosion-water-confining pressure damage. The proposed damage constitutive model employs the extremum method to ascertain the two Weibull distribution parameters (m and F0) by theoretical derivation and exhibits satisfactory conformity between the theoretical and experimental curves. The damage constitutive model can be consistent in the stress-strain characteristics of the rock triaxial compression process, which verifies the rationality and reliability of the model parameters. The model effectively represents the mechanical properties and damage characteristics of rocks when subjected to the combined influence of water chemistry and confinement. The presented model contributes to a better understanding of tangible rock-engineered structures subjected to chemical corrosion in underwater environments.

The Impact of Pulp Temperature on the Flotation Performance of Copper-Lead-Zinc Sulphide Ore

Flotation performance can significantly be affected by seasonal variations due to the changes in water temperature and pulp temperature, type and concentration of dissolved ions in process water. Extreme temperature conditions could be the major factor affecting flotation performance and mask the influence of water chemistry. Therefore, the interactive effects of the temperature and water chemistry should be taken into consideration, particularly for mine sites experiencing extreme temperature conditions. In this paper, effects of temperature, sulphate (SO42−), thiosulphate (S2O32−) and calcium (Ca2+) ions on the flotation performance of a Cu-Pb-Zn complex sulfide ore were investigated using a statistical experimental design and modelling approach. The results were evaluated using ANOVA and regression analysis to determine the significant parameters and derive individual regression models for each flotation response using Design Expert software version 6.0.8. Individual regression models were developed for mass pull, water recovery, grade and recovery of the sulfide minerals using the statistically significant main effects and their interactions. The models were used to determine the concentration of the dissolved ions and pulp temperature required to achieve the maximum zinc recovery, maximum zinc grade or the optimum zinc grade and recovery. The results showed that the water chemistry (i.e., the concentrations of Ca2+, SO42− and S2O32−) affected the flotation performance significantly at low temperature (25 °C). At high pulp temperature (60 °C), however, the temperature was the dominant parameter and masked the effects of water chemistry. Details of the statistical experimental design, discussions of the effects of experimental factors and their interactions on flotation performance, and the development of regression models are presented in this paper.

Rare earth elements (REEs) behavior in a large river across a geological and anthropogenic gradient

To meet the strong demand for green and digital technologies, the production of rare earth elements (REEs) has increased significantly, yet the fate of REEs (Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) in large rivers with multiple hydrological, geochemical, and anthropogenic gradients in their catchments remains poorly documented. Here we evaluated the spatial and temporal evolution of the concentrations, patterns, and speciation of REEs in surface waters along a 550 km transect of the St. Lawrence River (SLR) (Canada) and its tributaries from 2017 to 2020. Particulate and filtered (<0.45 µm) REEs concentrations increased downstream, suggesting that REEs found in the SLR predominantly originate from nearby tributaries, especially those draining the REE-rich Canadian Shield geological formation. Moreover, filtered concentrations were significantly higher in years that experienced intense spring freshets, indicating greater influence of runoff and surface soil processes on water chemistry of the SLR. Correlations with terrestrial-DOM, WHAM speciation modelling, and standardized patterns showed REEs speciation dominated by organic colloids, even in alkaline sites with low DOC and low terrestrial inputs. Strong positive correlations with Fe and Al suggested co-transport on organic matter and adsorption on oxyhydroxides. Compared to the influence of water chemistry and geology, the overall influence of anthropogenic inputs was generally low, although we observed an influence of increased erosion on particulate REEs and we measured anthropogenic gadolinium (Gd) at the Montréal wastewater outlet. Our results provide an integrative understanding of the fate of REEs through a geochemical and landscape perspective in one of the largest rivers in North America.

Applying Generic Water Quality Criteria to Cu and Zn in a Dynamic Aquatic Environment—The Case of the Brackish Water Formation Strömmen-Saltsjön

The EU Water Framework Directive stipulates that all EU waterways shall have good chemical and ecological status by 2027. Methodologies are described for how to assess and classify waterbodies and make 7-year management plans. Aquatic risk assessment methodologies and environmental quality standards are defined and a biotic ligand model methodology is available to assess the influence of water chemistry on the ability of aquatic organisms to take up metals. Aquatic status classification practices of naturally occurring river basin-specific metals are discussed, specifically how Cu and Zn water quality criteria guideline values have been adopted and defined for Swedish coastal and estuarine waters and how well they represent possible ecological risks. Calculations of bioavailability and ecotoxicity are conducted using recognised models for the Strömmen-Saltsjön water body in Stockholm, in which naturally occurring metals, especially Cu, have among the highest background concentrations of Sweden. Proposals are made to improve risk assessment methodologies to better reflect the vitality of living organisms, and to what extent current levels of these metals in Swedish waterways may influence their welfare. The study concludes that a more local assessment including, e.g., studies of the benthic fauna would be relevant for ecological status classification.

The Influence of pH on Zinc Lability and Toxicity to a Tropical Freshwater Microalga.

Increased focus on the development and application of bioavailability-based metal water quality guideline values requires increased understanding of the influence of water chemistry on metal bioavailability and toxicity. Development of empirical models, such as multiple linear regression models, requires the assessment of the influence of individual water quality parameters as toxicity-modifying factors. The present study investigated the effect of pH on the lability and toxicity of zinc (Zn) to a tropical green microalga (Chlorella sp.). Zinc speciation and lability were explored using the Windermere Humic Aqueous Model (WHAM7), ultrafiltration, and diffusive gradients in thin films (DGT). Zinc toxicity increased significantly with increasing pH from 6.7 to 8.3, with 50% growth inhibition effect concentrations decreasing from 185 to 53 µg l-1 across the pH range. Linear relationships between DGT-labile Zn and dissolved Zn did not vary across the tested pH range, nor did the linear relationship between dissolved (<0.45 µm) and ultrafiltered (<3 kDa) Zn. Our findings show that Zn toxicity to this freshwater alga is altered as a function of pH across environmentally realistic pH ranges and that these toxicity changes could not be explained by Zn speciation and lability as measured by DGT and WHAM7. Environ Toxicol Chem 2021;40:2836-2845. © 2021 SETAC.

Delineation of the exposure-response causality chain of chronic copper toxicity to the zebra mussel, Dreissena polymorpha, with a TK-TD model based on concepts of biotic ligand model and subcellular metal partitioning model

A toxicokinetic-toxicodynamic model was constructed to delineate the exposure–response causality. The model could be used: to predict metal accumulation considering the influence of water chemistry and biotic ligand characteristics; to simulate the dynamics of subcellular partitioning considering metabolism, detoxification, and elimination; and to predict chronic toxicity as represented by biomarker responses from the concentration of metals in the fraction of potentially toxic metal. The model was calibrated with data generated from an experiment in which the Zebra mussel Dreissena polymorpha was exposed to Cu at nominal concentrations of 25 and 50 μg/L and with varied Na+ concentrations in water up to 4.0 mmol/L for 24 days. Data used in the calibration included physicochemical conditions of the exposure environment, Cu concentrations in subcellular fractions, and oxidative stress-induced responses, i.e. glutathione-S-transferase activity and lipid peroxidation. The model explained the dynamics of subcellular Cu partitioning and the effect mechanism reasonably well. With a low affinity constant for Na + binding to Cu2+ uptake sites, Na + had limited influence on Cu2+ uptake at low Na+ concentrations in water. Copper was taken up into the metabolically available pool (MAP) at a largely higher rate than into the cellular debris. Similar Cu concentrations were found in these two fractions at low exposure levels, which could be attributed to sequestration pathways (metabolism, detoxification, and elimination) in the MAP. However, such sequestration was inefficient as shown by similar Cu concentrations in detoxified fractions with increasing exposure level accompanied by the increasing Cu concentration in the MAP.

A global Bayesian temperature calibration for lacustrine brGDGTs

Despite widespread use of branched glycerol dialkyl glycerol tetraethers (brGDGTs) for paleo-temperature reconstruction, no global calibration for their application in lakes has been generated since improved analytical methods have allowed for the separation of the structural isomers. This is a substantial obstacle for the application of this tool as soil calibrations underestimate temperature values when applied to lake sediments. Here, we present a comprehensive dataset (N=272) of lacustrine brGDGT distributions, consisting of both new and previously reported samples, spanning a wide range of geographical locations, air temperatures, and lakewater pH values. Empirical Orthogonal Function (EOF) analysis on the fractional abundance of brGDGTs indicates that temperature exerts a strong control (explaining 58% of the variance) on brGDGT distribution. The influence of water chemistry is weaker, with pH and conductivity explaining 24% of the variance. We use our dataset to generate a new Bayesian calibration to the mean temperature of Months Above Freezing (MAF), which has an R2=0.82 and RMSE = 2.9°C. Application of the new temperature calibration to a previously published lake core record spanning the last 900 years demonstrates that it generates values comparable to instrumental observations of MAF. Our new calibration facilitates the use of lacustrine brGDGTs to reconstruct continental temperatures, a vital piece of information for understanding past climates.

Efficient elimination of uranium by carboxymethyl-β-cyclodextrin nanoparticles decorated iron oxides: Water chemistry influences and mechanism researches

Environmental radionuclides’ contaminations have attracted widespread concerns owing to their austere hazardousness in physicochemical and accumulative bio-toxicities. Herein, magnetic carboxymethyl-β-cyclodextrin coated iron oxides nanoparticles (CM-CD-MNPs) were successfully fabricated using the chemical co-precipitation approach. The removal performances of uranium onto CM-CD-MNPs under various environmental conditions were investigated by macroscopical experiments and photoelectron spectroscopy. The reaction kinetic reactions and adsorption isotherms of uranium onto CM-CD-MNPs could be satisfactorily simulated using pseudo-second-order kinetic model and Langmuir model, respectively. The maximum adsorption capacity of U(VI) onto the CM-CD-MNPs was calculated to be nearly 5.75 × 10−4 mol/g, which was higher than many nanomaterials reported in literatures. The interactive mechanism of U(VI) onto CM-CD-MNPs composites was primarily commanded through surface complexation, chemical co-precipitation along with electrostatic attraction. The CM-CD-MNPs composites can be recycled and regenerated with acceptable reusability and possessed significant application potentials in the immobilization of U(VI) from nuclear fuel partition or nuclear waste management.

Aluminum compound forms in the Al–H2O system as applied to operating conditions of Dry Cooling Towers

One of important indicators of reliable operation of the steam-water cycle at power plants is water chemistry. Special chemicals are used to adjust properties of working fluids. At designing a new unit the chemicals are selected on the basis of parameters of water, steam and materials, used in different parts of the cycle.Another indicator is minimizing the cooling water loss. Typical loss of cooling water is about 5% of total water amount. This loss is associated with evaporation, droplet carry-over, and blowdown in cooling towers.For power plants, it is typically recommended to use dry cooling towers for minimizing the cooling water loss. In dry cooling systems, cooling water with low amount of impurities goes to mixing condenser, where turbine steam condensation occurs. Then one portion of mixed water flow at the condenser outlet is supplied to the boiler or steam generator feed water loop. Another portion is returned back to the cooling tower. Inside the cooling tower, water is cooled down by passing through air-cooled heat exchangers manufactured of aluminium or steel alloys.On the basis of Pourbaix diagram it is proposed to evaluate the influence of water chemistry on the forms of existence of aluminium compounds in dry cooling towers. The results of calculations are compared with the experimental data.

BIOMONITORING LAKE CHEBARKUL WATER ON MACROPHYTE COMMUNITY, RUSSIA

The article studies macrophyte biodiversity in Lake Chebarkul (Russia) and the influence of water chemistry on it. The macrophyte community composition is sensitive to any environmental changes. Higher or lower trophic status is the most important factor responsible for changing taxons of high environmental value (sensitive taxon) into potentially ruderal species. This is typical for the areas with an increased anthropogenic impact on the lake. This paper identifies species diversity, the taxonomic structure of aquatic flora for each section of the lake. Macrophytes were studied along the lake shore both with the help of qualitative and quantitative analysis. The lake flora was listed for each lake profile, and then the general list of differences and similarities for all the studied sites was compiled. The final flora list includes about 90 spices plants. According to the study results, the macrophyte species composition of the studied sites is different. 59 % of the total number of taxa was present at all sites, while 9 % of them, mostly sensitive taxa, were found only in a group of points with relatively clean water. However, the overgrowth was highest in the fourth group (102 %), slightly lower at the points of the third group (92 %) and significantly lower in the second (58 %) and first (44 %) groups. The article considers the possibility of bioindication quality with the biomass of common macrophytes- Potamogeton lucens L., P. obtusifolius, P. pusillus, P. crispus andPhragmites australis L. of Lake Chebarkul (Russia).

Graphene oxide sponge as adsorbent for organic contaminants: comparison with granular activated carbon and influence of water chemistry

A graphene oxide sponge with hierarchical porosity outperforms Norit GAC for removal of methylene blue.

Identification of key parameters of magnetite deposition on steam generator surfaces—Modeling and preliminary experiments

The present paper describes a sensitivity study of the fundamental parameters of a deposition model for magnetite on secondary circuit surfaces in terms of their relative influence on the individual steps of the overall process. First, a description of the processes of particle deposition and detachment is presented, emphasizing the role of Van der Waals and electrostatic forces, as well as the roughness of both particle and substrate. Particular attention is paid to the influence of water chemistry on these interaction forces. Further, the paper attempts to propose a mechanism for deposit consolidation modelled as a crystallization reaction and discusses the sensitivity of parameters of a Johnson-Mehl-Kolmogorov-Avrami approach to such a reaction. In the experimental part of the paper, preliminary results on the influence of temperature and water chemistry on the one of the key parameters – the zeta-potential of magnetite – are described and discussed. The results are successfully reproduced using a recent model from the literature on compatible media.

Influence of water chemistry on colloid-size Cu-based pesticides particles: A case of Cu(OH)2 commercial fungicide/bactericide

The intensive, widespread, and ever-increasing applications of Cu-based pesticides in agriculture could potentially increase environmental exposures via different routes. Unlike ionic/bulk forms, the fate, transport, and toxicity of colloid-size Cu-based pesticides are not well studied. This paper provides evaluation outcomes of granule and dispersion characterizations, stability, and dissolution of colloid-size particles of Cu(OH)2 commercial pesticide product at a range of water chemistry. The evaluated product contained about 35% weight of metallic Cu equivalent and Cu(OH)2 particles with sizes < 1 μm of which a fraction of nanoscale particles exist. The presence of Ca2+ at ionic strengths of >0.01 M and 0.001–0.2 M significantly influenced (p < 0.001) particle size (PS) and ζ-potential values, respectively at all investigated pH values. Cu dissolution at pH 5.5 was significant (p < 0.001) and exceeded Cu dissolutions at pH 7.0 by 87–90% and at pH 8.5 by 87–95% in all dispersions. The order of Cu dissolution was pH 5.5 > pH 7.0 > pH 8.5 in all dispersions. Cu dissolution was relatively reduced by 53% by increasing HA from 0 to 5 mg L−1 and enhanced by 55% by increasing HA from 5 to 15 mg L−1, however, the overall Cu dissolution was decreased by 27% by increasing HA from 0 to 15 mg L−1. Thus, HAs reduced the dissolution of Cu at pH < 7. The findings provide an insight into how water chemistry influences the fate and transport of colloid-size Cu-based pesticides particles.

Comparison of microbial respiration and carbon loss in the upper Ohio River and selected tributaries in the Northern Panhandle of West Virginia

Stream microorganisms can drive ecosystem processes, such as carbon cycling; however, changes in water chemistry can slow down or speed up the rate that carbon moves through the ecosystem. When microorganisms respire, inorganic carbon is released back into the system. In this study, we investigated the influence of water chemistry on microbial respiration and the breakdown of organic matter using two types of standardized substrates: labile cellulose sponge and recalcitrant red oak wood veneer. The rate of breakdown of these substrates correlated positively with increasing microbial respiration rates. Water chemistry data was used to assess for correlation with the microbial respiration rates. Specific conductance (SPC) was found to be a significant predictor model of microbial respiration rates; as SPC increased, microbial respiration rates increased. These correlations could provide us with new ways to predict the effects of stressors on multiple aspects of aquatic ecosystems, such as carbon cycling.

Waterborne pharmaceutical uptake and toxicity is modified by pH and dissolved organic carbon in zebrafish

Human and veterinary pharmaceuticals have been observed in natural aquatic environments around the world, and many have been shown to impact fish health. Presently, we examined the influence of pH, dissolved organic carbon (DOC) and Na+ or Ca2+ on the bioavailability and toxicity of waterborne pharmaceuticals in larval zebrafish. Drugs included sertraline (selective serotonin reuptake inhibitor; SSRI), fluoxetine (SSRI), diclofenac (nonsteroidal anti-inflammatory drug) and ethinyl estradiol (estrogen; EE2). The 96 h-LC50s for sertraline, fluoxetine and diclofenac were influenced by pH over an environmentally relevant range (pH 5.8–8.2). Toxicity was related to the predicted concentration of non-ionized compounds, which more readily cross cell membranes than ionized compounds. For example, sertraline was 4.1-fold more toxic (as measured by 96 h-LC50s) at pH 8.2 compared to pH 5.8, while the predicted amount of non-ionized sertraline was also greater at pH 8.2 (based on previously reported pKa values). Experiments with radiolabelled drugs demonstrated that sertraline uptake was also 5.4-fold higher at pH 8.2 compared to pH 5.8. Terrigenous and autochthonous DOC samples (as low as 1 mg/L) protected against sertraline uptake and toxicity, although they were more effective at lower (environmentally relevant) drug concentrations. In contrast, the uptake of EE2, which was principally non-ionized in all water chemistries tested, was not altered by pH or DOC. There was no change in sertraline toxicity with the addition of 12 mM Na+ or 3 mM Ca2+. In conclusion, the influence of pH and DOC on drug uptake and toxicity in fish appears to be predictable based on the physicochemical properties of the drug (e.g. pKa, polar surface area). The influence of water chemistry on drug bioavailability in fish is likely relevant to all aquatic life.

Corrosion Behavior and Oxide Films of New Zirconium Cladding Corroded at Different Conditions

Zirconium alloys are mostly served as the cladding materials in water reactors. Corrosion is one of the concerning problems in zirconium utilization. Transition of corrosion occurs every 2~3 μm in thickness, but its mechanism is not confirmed. To study the influence of water chemistry and the mechanism behind transition, a new type of zirconium cladding was tested for three corrosion conditions: the pure water, LiOH solution, LiOH/H3BO3 solution at 360°C/18.6MPa. For all cases, Zr-0.5Sn-0.15Nb-0.5Fe-0.2V cladding had a lower corrosion rate and a longer transition time than N36 cladding. The corrosion results showed that the corrosion rate was the highest and the transition time was the shortest in LiOH solution. Oxide phase information on the oxidized surface was obtained by Raman study. Tetragonal zirconia, embedded in the surface, was found at the beginning of corrosion. As the corrosion time increased, tetragonal phase stress was almost released and the content of tetragonal phase was also decreased to zero at the transition point. Stable tetragonal phase was found on the samples corroded in pure water. However, in LiOH solution, it was eliminated the quickest. The acceleration of transition in LiOH solution is partly resulted from the fast transformation of tetragonal phase. The reason for the longer transition time in N2 cladding can be directly attributed to the smaller decrease of the tetragonal phase.

Organic selenium, selenate, and selenite accumulation by lake plankton and the alga Chlamydomonas reinhardtii at different pH and sulfate concentrations

Selenium (Se) concentrations measured in lake planktonic food chains (microplankton <64 μm, copepods, and Chaoborus larvae) were strongly correlated with the concentrations of dissolved organic Se. These correlations were strengthened slightly by adding the concentrations of dissolved selenate to those of organic Se. To better understand the role of Se species and the influence of water chemistry on Se uptake, we exposed the green alga Chlamydomonas reinhardtii to selenite, selenate, or selenomethionine at various H+ ion and sulfate concentrations under controlled laboratory conditions. At low sulfate concentrations, inorganic Se species (selenate >> selenite) were more readily accumulated by this alga than was selenomethionine. However, at higher sulfate concentrations the uptake of selenite was higher than that of selenate, whereas the uptake of selenomethionine remained unchanged. Although the pH of the exposure water did not influence the uptake of selenate by this alga, the accumulation of selenomethionine and selenite increased with pH because of their relative pH-related speciation. The Se concentrations that we measured in C. reinhardtii exposed to selenomethionine were 30 times lower than those that we measured in field-collected microplankton exposed in the same laboratory conditions. This difference is explained by the taxa present in the microplankton samples. Using the present laboratory measurements of Se uptake in microplankton and of natural Se concentrations in lake water allowed us to model Se concentrations in a lake pelagic food chain. Environ Toxicol Chem 2018;37:2112-2122. © 2018 SETAC.

Distribution of trace elements and the influence of major‐ion water chemistry in saline lakes

AbstractAlthough the water chemistry in saline lakes can differ drastically due to subtle differences in inflowing water conditions, the concentrations, distributions, and geochemical behaviors of trace elements in such environments are poorly understood. In this study, the influence of major‐ion chemistry on the trace element distribution in saline lakes is examined based on major and trace element concentrations and geochemical modeling in three carbonate‐rich saline lakes located in Mongolia and Turkey. The results are compared to data reported from other carbonate‐rich and carbonate‐depleted lakes. The concentrations of U and oxyanions (V, Mo, and W) in carbonate‐rich saline lakes are several orders of magnitude higher than their contributing rivers and seawater. By contrast, their concentrations in carbonate‐depleted saline lakes are lower than those in rivers and oceans. The high U concentrations in carbonate‐rich saline lakes are possibly attributed to the formation of (magnesium–)uranyl–carbonate complexes, and the high oxyanion concentrations are likely a result of the high pH of lake water preventing them from being adsorbed onto solid phases such as suspended particulate matter and sediment. Strontium and Ba concentrations are lower in carbonate‐rich saline lakes than in river water and seawater, but relatively higher in carbonate‐depleted lakes. Incorporation into aragonite and/or calcite, adsorption onto solid phases, and formation of carbonate minerals are possible mechanisms that may account for the lower concentrations of these elements in carbonate‐rich lakes. These results help elucidate the influence of water chemistry on trace element distribution in saline lakes.

Seasonal variability of natural water chemistry affects the fate and behaviour of silver nanoparticles

Understanding the environmental behaviour of nanoparticles (NPs) after release into aquatic systems is essential to predict the environmental implications of nanotechnology. Silver nanoparticles (AgNPs) represent a major class of engineered NPs with a significant potential for environmental impact. Therefore, investigating their transformations in natural waters will help predict their long term environmental fate and behaviour. AgNPs were characterized in natural lake water collected seasonally from the same freshwater source, using column microcosms to assess their behaviour and transport at different depths. Building on our previous work using similar systems with synthetic waters, the influence of water chemistry and NP surface modifications on colloidal stability and dissolution in natural lake water over time was investigated. A simple sedimentation-diffusion model parameterized by the particle properties and total Ag concentration was successfully used to understand AgNPs transport behaviour. PVP coated AgNPs remained colloidally stable, with their transport in the water column dominated by diffusion, and exhibited no significant or substantial changes in data or model parameters for different seasons. Citrate coated AgNPs were susceptible to rapid aggregation, sedimentation, dissolution and reprecipitation; their transport in the water column was determined by both diffusion and sedimentation.