Bicarbonate Ion Concentration Research Articles

Passivation and depassivation of reinforcement steel in alkali-activated materials—A review

This paper reviews the formation and breakdown of passive film on the surface of reinforcement steel in alkali-activated materials (AAMs) considering the characteristics of reaction product and pore solution chemistry. The literature review shows that the pore solution of AAMs has higher concentrations of OH−, Na+, silica and aluminium compared to Portland cement (PC). This relatively high alkalinity contributes to the generation of a passive film, which has positive effects on the corrosion resistance of reinforcement steel embedded in AAMs. The silica-aluminium zeolite layer present on the surface of passive film adsorbs chloride ions and effectively inhibits chloride-induced depassivation. Generally, lower ratios of [Cl−]/[SO42−] and [Cl−]/[S2O32−] potentially inhibit the depassivation of reinforcement steel. The high pH value and the elevated concentrations of HS− of AAMs contribute to the increase of critical chloride content (Ccrit). However, the higher content of reduced sulfide mainly dissolved from slag results in the consumption of dissolved oxygen, which is necessary for the formation of passive film. Generally, the presence of reduced sulfide forms Fe-S complexes on the surface of reinforcement steel in AAMs. Even so, higher corrosion resistance for AAMs is mostly expected with longer depassivation time due to finer microstructure and lower chloride penetration rates compared to PC-based materials. The decrease in pH value in the pore solution of the AAMs is the main factor affecting carbonation-induced depassivation of reinforcement steel, while high concentrations of bicarbonate and carbonate ions inhibit depassivation.

Heterogeneous Activation of Persulfate by Petal-Shaped Co3O4@BiOI to Degrade Bisphenol AF

In catalytic tests, the results have shown that almost all the BPAF was removed within 30 min when the dosage of Co3O4@BiOI and sodium persulfate (PS) was 0.15 g and 0.1 mM, respectively. Acid conditions inhibited BPAF degradation, but the inclusion of a precise concentration of bicarbonate ions (HCO3−) promoted degradation. The presence of chloride (Cl−), sulfate ions (SO42−), and a high concentration of HCO3− inhibited the degradation process, whereas the addition of nitrate ions (NO3−) had a minor effect on the catalytic process. The presence of free radicals (sulfate (SO4•−), hydroxyl (•OH), and superoxide (O2•−)) and the non-free radical singlet oxygen (1O2) in the Co3O4@BiOI/PS system was determined by electron paramagnetic resonance (EPR) and quenching tests. We propose that the Co(II)/Co(III) and Bi(III)/Bi(V) redox pairs simultaneously activate PS where the Co3O4 and BiOI components work synergistically to promote the rapid oxidative degradation of BPAF in water.

Ocean alkalinity enhancement using sodium carbonate salts does not lead to measurable changes in Fe dynamics in a mesocosm experiment

Abstract. The addition of carbonate minerals to seawater through an artificial ocean alkalinity enhancement (OAE) process increases the concentrations of hydroxide, bicarbonate, and carbonate ions. This leads to changes in the pH and the buffering capacity of the seawater. Consequently, OAE could have relevant effects on marine organisms and in the speciation and concentration of trace metals that are essential for their physiology. During September and October 2021, a mesocosm experiment was carried out in the coastal waters of Gran Canaria (Spain), consisting on the controlled variation of total alkalinity (TA). Different concentrations of carbonate salts (NaHCO3 and Na2CO3) previously homogenized were added to each mesocosm to achieve an alkalinity gradient between Δ0 to Δ2400 µmol L−1. The lowest point of the gradient was 2400 µmol kg−1, being the natural alkalinity of the medium, and the highest point was 4800 µmol kg−1. Iron (Fe) speciation was monitored during this experiment to analyse total dissolved iron (TdFe, unfiltered samples), dissolved iron (dFe, filtered through a 0.2 µm pore size filter), soluble iron (sFe, filtered through a 0.02 µm pore size filter), dissolved labile iron (dFe′), iron-binding ligands (LFe), and their conditional stability constants (KFeL′) because of change due to OAE and the experimental conditions in each mesocosm. Observed iron concentrations were within the expected range for coastal waters, with no significant increases due to OAE. However, there were variations in Fe size fractionation during the experiment. This could potentially be due to chemical changes caused by OAE, but such an effect is masked by the stronger biological interactions. In terms of size fractionation, sFe was below 1.0 nmol L−1, dFe concentrations were within 0.5–4.0 nmol L−1, and TdFe was within 1.5–7.5 nmol L−1. Our results show that over 99 % of Fe was complexed, mainly by L1 and L2 ligands with kFe′L′ ranging between 10.92 ± 0.11 and 12.68 ± 0.32, with LFe ranging from 1.51 ± 0.18 to 12.3 ± 1.8 nmol L−1. Our data on iron size fractionation, concentration, and iron-binding ligands substantiate that the introduction of sodium salts in this mesocosm experiment did not modify iron dynamics. As a consequence, phytoplankton remained unaffected by alterations in this crucial element.

Multiple carbonate system parameters independently govern shell formation in a marine mussel

Calcification is vital to marine organisms that produce calcium carbonate shells and skeletons. However, how calcification is impacted by ongoing environmental changes, including ocean acidification, remains incompletely understood due to complex relationships among the carbonate system variables hypothesized to drive calcification. Here, we experimentally decouple these drivers in an exploration of shell formation in adult marine mussels, Mytilus californianus. In contrast to models that focus on single parameters like calcium carbonate saturation state, our results implicate two independent factors, bicarbonate concentration and seawater pH, in governing calcification. While qualitatively similar to ideas embodied in the related substrate-inhibitor ratio (bicarbonate divided by hydrogen ion concentration), our data highlight that merging bicarbonate ion and hydrogen ion concentrations into a simple quotient obscures important features of calcification. Considering a dual-parameter framework improves mechanistic understanding of how calcifiers interact with complex and changing chemical conditions.

Discovery of a hyperalkaline liquid condensed phase: significance toward applications in carbon dioxide sequestration.

Bicarbonate ion-containing solutions such as seawater, natural brines, bovine serum and other mineralizing fluids have been found to contain hyperalkaline droplets of a separate, liquid condensed phase (LCP), that have higher concentrations of bicarbonate ion (HCO3 -) relative to the bulk solution in which they reside. The existence and unique composition of the LCP droplets have been characterized by nanoparticle tracking analysis, nuclear magnetic resonance spectroscopy, fourier transform infrared spectroscopy, dissolved inorganic carbon analysis and refractive index measurements. Carbon dioxide can be brought into solution through an aqueous reaction to form LCP droplets that can then be separated by established industrial membrane processes as a means of concentrating HCO3 -. Reaction of calcium with the LCP droplets results in calcium carbonate precipitation and mineral formation. The LCP phenomenon may bear on native mineralization reactions and has the potential to change fundamental approaches to carbon capture, sequestration and utilization.

Effect of Ba2+ on the biomineralization of Ca2+ and Mg2+ ions induced by Bacillus licheniformis.

The effect of barium ions on the biomineralization of calcium and magnesium ions is often overlooked when utilizing microbial-induced carbonate precipitation technology for removing barium, calcium, and magnesium ions from oilfield wastewater. In this study, Bacillus licheniformis was used to bio-precipitate calcium, magnesium, and barium ions. The effects of barium ions on the physiological and biochemical characteristics of bacteria, as well as the components of extracellular polymers and mineral characteristics, were also studied in systems containing coexisting barium, calcium, and magnesium ions. The results show that the increasing concentrations of barium ions decreased pH, carbonic anhydrase activity, and concentrations of bicarbonate and carbonate ions, while it increased the contents of humic acids, proteins, polysaccharides, and DNA in extracellular polymers in the systems containing all three types of ions. With increasing concentrations of barium ions, the content of magnesium within magnesium-rich calcite and the size of minerals precipitated decreased, while the full width at half maximum of magnesium-rich calcite, the content of O-C=O and N-C=O, and the diversity of protein secondary structures in the minerals increased in systems containing all three coexisting ions. Barium ions does inhibit the precipitation of calcium and magnesium ions, but the immobilized bacteria can mitigate the inhibitory effect. The precipitation ratios of calcium, magnesium, and barium ions reached 81-94%, 68-82%, and 90-97%. This research provides insights into the formation of barium-enriched carbonate minerals and offers improvements for treating oilfield wastewater.

Flood-spreading effects on the chemical properties of the soil: a case study of the Tasuj station, Iran

ABSTRACT The objective of this paper is to determine whether the flood-spreading system at the Tasuj station in east Azerbaijan, Iran, has caused inappropriate chemical alterations to the properties of the soil. One question is whether the flood-spreading system was constructed at an inappropriate location leading to unintentional consequences. Composite soil samples were taken from three flooded areas, from three grids in each flooding area, and from two depths. Chemical characteristics of the soil including electrical conductivity, pH, concentrations of bicarbonate, chloride, sodium, calcium, and magnesium ions, and the sodium adsorption ratio in the flooded areas were measured. Because of calcareous, gypsum, shale, and marl formations in the first flooded area, dissolution of solutes of these formations increased the concentration of ions in the runoff (especially sodium and chlorine, to 19.50 and 21.90 mmol (charge) L−1, respectively). These high ion concentrations caused the electrical conductivity of the runoff to increase significantly (up to 2.03 dS/m) compared to the other areas. High amounts of lime in the soil caused increasing buffering capacity of the area soil, as a consequence the flood-spreading did not cause significant changes to the soil pH and showed a difference of only 0.3–0.2 in the first flooded area compared to other areas.

ТЕНДЕНЦИИ ИЗМЕНЕНИЯ ИОННОГО СОСТАВА ЛАДОЖСКОГО ОЗЕРА

The sum of ions of the basic Lake Ladoga water mass has varied quite significantly from 55.6 to 71.6 mg/L over the past 60 years. In the present paper, separate periods of the mineralization growth are identified. It is shown that the change in the mineralization of Lake Ladoga has been always accompanied by a significant change in the ratio of basic ion concentrations. Any significant trends in the total mineralization of Lake Ladoga over the analyzed period have not been identified, but periods of the growth and decrease in the number of ions have been revealed. Until 1998, the periods of increased mineralization, as a rule, were accompanied by an increase in concentrations of SO42 and Cl, most likely coming from the catchment area due to industrial and household pollution. During 2009-2019, the mineralization was growing mainly due to an increase in the absolute and relative concentrations of HCO3. At the same time, the concentration of dissolved CO2 in the main water mass of the lake also was increasing (and, consequently, pH was decreasing). Thus, the changes in the bicarbonate ion concentration in the water of Lake Ladoga may be largely determined by an increase in its inflow from the catchment area, whose possible reason is the enhancement of the chemical weathering of carbonate rocks due to the increasing concentrations of dissolved CO2 in the water.

Synchrony in Networks of Type 2 Interneurons Is More Robust to Noise with Hyperpolarizing Inhibition Compared to Shunting Inhibition in Both the Stochastic Population Oscillator and the Coupled Oscillator Regimes.

Synchronization in the gamma band (25-150 Hz) is mediated by PV+ inhibitory interneurons, and evidence is accumulating for the essential role of gamma oscillations in cognition. Oscillations can arise in inhibitory networks via synaptic interactions between individual oscillatory neurons (mean-driven) or via strong recurrent inhibition that destabilizes the stationary background firing rate in the fluctuation-driven balanced state, causing an oscillation in the population firing rate. Previous theoretical work focused on model neurons with Hodgkin's Type 1 excitability (integrators) connected by current-based synapses. Here we show that networks comprised of simple Type 2 oscillators (resonators) exhibit a supercritical Hopf bifurcation between synchrony and asynchrony and a gradual transition via cycle skipping from coupled oscillators to stochastic population oscillator (SPO), as previously shown for Type 1. We extended our analysis to homogeneous networks with conductance rather than current based synapses and found that networks with hyperpolarizing inhibitory synapses were more robust to noise than those with shunting synapses, both in the coupled oscillator and SPO regime. Assuming that reversal potentials are uniformly distributed between shunting and hyperpolarized values, as observed in one experimental study, converting synapses to purely hyperpolarizing favored synchrony in all cases, whereas conversion to purely shunting synapses made synchrony less robust except at very high conductance strengths. In mature neurons the synaptic reversal potential is controlled by chloride cotransporters that control the intracellular concentrations of chloride and bicarbonate ions, suggesting these transporters as a potential therapeutic target to enhance gamma synchrony and cognition.

A numerical study of CaCO3 deposition on the membrane surface of direct contact membrane distillation

This numerical study investigates the effect of CaCO3 deposition on the performance of direct contact membrane distillation (DCMD). It is the first numerical study to directly evaluate the deposition and film thickness of CaCO3 on the membrane surface. Therefore, a 3D computational fluid dynamics (CFD) model, which combines momentum, heat, species transport reaction, and the Eulerian wall film model, is used to analyze the CaCO3 mass deposition rate and scaling deposition thickness on the membrane surface. HSC Chemical Software is used to evaluate the ion compositions and reaction kinetics, including the activation energy (Ea) and pre-exponential factor (Ar). The CFD model is validated with experimental results. The results reveal that the CaCO3 deposition rate increases significantly at a high temperature, velocity, and salinity of the solution. The CaCO3 mass deposition increased by 15 times and scaling deposition thickness increased from 0.05 nm to 1 nm when the temperature was raised from 318.15 K to 348.15 K, whereas an increase of approximately 25 % in deposition was observed with an increase in velocity from 0.17 to 1.38 m/s at a concentration of calcium (Ca+2) ions, 0.03 % and bicarbonate (HCO3−) ions 0.004 %. The results also indicate that CaCO3 deposition decreases the flux and efficiency of the DCMD by 2 % with a low concentration of Ca+2 ions, 0.03 %, and HCO3− ions, 0.004 %. The findings indicate that the high feed salinity (75.23 g/l) increases CaCO3 mass deposition and scaling deposition thickness on the membrane surface due to the high concentration of Ca+2 ions, 0.07 %, and HCO3− ions, 0.01 %, significantly reducing the permeate flux by 14 %. The study's model development and implementation can be adjusted to offer guidance for studying the MD process in treating high saline water with fouling issues.

Study on influencing factors of wellbore scaling during ASP flooding

In the middle and later stages of oil and gas field development, the produced fluid carries a large amount of formation scaling ions. During the entire extraction process, changes in parameters such as temperature, pressure, and flow rate can disrupt the original equilibrium and cause collisions between scaling ions. The scale particles formed by chemical reactions aggregate and deposit on the cylinder wall, causing scaling. The accumulation of scale not only causes wellbore blockage, but also irreversible damage to the production well. In order to study the scaling problem of oil production wells, the scaling mechanism was studied through indoor experiments. On this basis, a numerical model for the formation of wellbore scaling was established, and the mass fraction distribution of CaCO3 scaling particles at different positions in the wellbore was studied. The results indicate that: (1) the main type of scale sample is calcium carbonate, and as the concentration of calcium carbonate and sulfate ions increases, the amount of scale and corrosion will increase; (2) As the concentration of bicarbonate ions increases, the amount of scaling increases and the amount of corrosion decreases. (3) The mass fraction of calcium carbonate scaling at the upper and lower parts of the oil pump cavity and the sucker rod coupling decreases with increasing temperature, decreases with increasing initial inlet speed, and increases with increasing scaling ion concentration. The research results of this paper provide theoretical and technical support for predicting the scaling law of production Wells, improving the pumping inspection period of pumping units and ensuring the safety of oil Wells.

Phenols and GABAA receptors: from structure and molecular mechanisms action to neuropsychiatric sequelae.

γ-Aminobutyric acid type A receptors (GABAARs) are members of the pentameric ligand-gated ion channel (pLGIC) family, which are widespread throughout the invertebrate and vertebrate central nervous system. GABAARs are engaged in short-term changes of the neuronal concentrations of chloride (Cl-) and bicarbonate (HCO3 -) ions by their passive permeability through the ion channel pore. GABAARs are regulated by various structurally diverse phenolic substances ranging from simple phenols to complex polyphenols. The wide chemical and structural variability of phenols suggest similar and different binding sites on GABAARs, allowing them to manifest themselves as activators, inhibitors, or allosteric ligands of GABAAR function. Interest in phenols is associated with their great potential for GABAAR modulation, but also with their subsequent negative or positive role in neurological and psychiatric disorders. This review focuses on the GABAergic deficit hypotheses during neurological and psychiatric disorders induced by various phenols. We summarize the structure-activity relationship of general phenol groups concerning their differential roles in the manifestation of neuropsychiatric symptoms. We describe and analyze the role of GABAAR subunits in manifesting various neuropathologies and the molecular mechanisms underlying their modulation by phenols. Finally, we discuss how phenol drugs can modulate GABAAR activity via desensitization and resensitization. We also demonstrate a novel pharmacological approach to treat neuropsychiatric disorders via regulation of receptor phosphorylation/dephosphorylation.

Mn2+ recycling in hypersaline wastewater: unnoticed intracellular biomineralization and pre-cultivation of immobilized bacteria.

Microbially induced manganese carbonate precipitation has been utilized for the treatment of wastewater containing manganese. In this study, Virgibacillus dokdonensis was used to remove manganese ions from an environment containing 5% NaCl. The results showed a significant decrease in carbonic anhydrase activity and concentrations of carbonate and bicarbonate ions with increasing manganese ion concentrations. However, the levels of humic acid analogues, polysaccharides, proteins, and DNA in EPS were significantly elevated compared to those in a manganese-free environment. The rhodochrosite exhibited a preferred growth orientation, abundant morphological features, organic elements including nitrogen, phosphorus, and sulfur, diverse protein secondary structures, as well as stable carbon isotopes displaying a stronger negative bias. The presence of manganese ions was found to enhance the levels of chemical bonds O-C=O and N-C=O in rhodochrosite. Additionally, manganese in rhodochrosite exhibited both + 2 and + 3 valence states. Rhodochrosite forms not only on the cell surface but also intracellularly. After being treated with free bacteria for 20days, the removal efficiency of manganese ions ranged from 88.4 to 93.2%, and reached a remarkable 100% on the 10th day when using bacteria immobilized on activated carbon fiber that had been pre-cultured for three days. The removal efficiency of manganese ions was significantly enhanced under the action of pre-cultured immobilized bacteria compared to non-pre-cultured immobilized bacteria. This study contributes to a comprehensive understanding of the mineralization mechanism of rhodochrosite, thereby providing an economically and environmentally sustainable biological approach for treating wastewater containing manganese.

Comparative study of the quality of water produced by a solar distiller and by reverse osmosis

Freshwater is a vital resource for human well-being, accounting for about 2.5% of the water on our planet. However, the growing demand for freshwater puts its quality at risk. For meeting the water needs, desalination is a crucial solution, but it needs to be ensured that the water quality meets the international standards. In this article, we will compare the physical and chemical characteristics of water produced by solar distillation and reverse osmosis, using the same source water. We started with saline water with a pH ranging from 7.70 to 7.80, conductivity ranging from 49.5 to 51 ms/cm, and bicarbonate ion concentration ranging from 125 to 145 mg/l. We used a solar distiller and reverse osmosis to obtain distilled water with a pH of 7 to 7.20, conductivity of 0.2 to 1.6 ms/cm, and bicarbonate ion concentration of 14 to 28.5 mg/l. The results we obtained were found to comply with international drinking water standards.

Groundwater storage change represents as a significant source of atmospheric CO<sub>2</sub> in China

<p>Recent studies show that groundwater depletion is an unreported source of atmospheric CO<sub>2</sub> through bicarbonate reactions in the groundwater released from aquifer. However, the depletion can be mitigated or offset by recharge, and thus the contrasting roles of depletion and recharge on carbon cycle remain unclear at a national scale. Here, we extend previous studies to use the satellite�Cderived groundwater storage change (GWSC) and substantial in situ measurements of the bicarbonate ion concentration (BIC), for the first time evaluation of GWSC�Cinduced CO<sub>2</sub> emission/sequestration in China. Results show that the GWSC represents as a significant source of atmospheric CO<sub>2</sub> in China, with a net CO<sub>2</sub> emission rate of 2.1��2.3 Mt/yr, which is larger than 15% of the emission sources listed in China Carbon Emission Accounts and Datasets. Besides, emission and sequestration induced by groundwater storage (GWS) decrease and increase is also significant, with a rate of 3.9��1.1 Mt/yr and 1.8��1.2 Mt/yr, respectively. Notably, we also find that China��s stricter groundwater measures can contribute a total reduction of 5.3 Mt CO<sub>2</sub> emission in the major overdraft areas by 2025. Despite of notable uncertainties, this study highlights the unneglectable contributions of GWSC to atmospheric CO<sub>2</sub> emission and sequestration at a national to global scale.</p>

Evaluation of Some Biochemical Parameters in Glucose-6-Phosphate Dehydrogenase deficient subjects of Hausa and Fulani ethnics

Glucose-6-phosphate dehydrogenase deficiency is a significant public health problem that is implicated in the pathogenesis of a number of common diseases via increased oxidative stress and a decrease in the generation of nitric oxide. There is little information about its impact on some organ, hence the need for this research. This was a case-control study carried out on Hausa and Fulani ethnics in Kano. Heparinized 5 ml venous blood specimen were collected from 140 individuals (70 deficient and 70 control) aged between 18-35 years selected for the study to determine the blood levels of some biochemical parameters using standard methods. There were significant increase in transaminases (p<0.001), but significant decrease concentrations of sodium (p<0.05), chloride (p<0.001), alkaline phosphatase (p<0.001) and total protein (p<0.001) whereas there was no statistically significant difference (p>0.05) in the plasma concentration of albumin, total bilirubin, conjugated bilirubin, urea, creatinine, potassium and bicarbonate ions. Our results demonstrate extremely significantly lower (p<0.001 for all) concentration in glutathione reductase, total antioxidants potential, copper, zinc and non-significant decrease (p>0.05) in manganese level of G-6-PD deficient patients compared to controls, whereas malondialdehyde level showed an increasing trend on contrary. However, there were correlations between G-6-PD activity and oxidative stress markers. The findings of the present study suggest that liver and kidneys functions were not altered among people living with G-6-PD deficiency but induce oxidative stress which is not capable of causing organ impairment.

Multiscale modelling of species transport in hydrophilic Nafion®-coated Cu catalysts for CO2 electro-reduction

Ionomers such as Nafion are being used for engineering the microenvironment of the CO2RR towards selectivity to higher hydrocarbons. Their cationic exchange qualities mitigate homogeneous bicarbonate reactions, providing favourable conditions for production of C2-C3 products. The proximity of Nafion® layers to the negatively charged electrode surface results in complex effects that have yet to be explored computationally. We combine mass transport equations and density functional theory (DFT) calculations to model the hydrophilic moieties in Nafion® layer on a 1D planar copper electrode. We vary the Nafion® layer thickness in the thick film regime (200–1100 nm), the ionic strength of supporting aqueous electrolyte and the applied voltage to investigate the concentration profile of participating species within the Nafion® layer. We find that the bicarbonate ion concentration and local pH decrease with decreasing thickness which makes thinner films better at mitigating bicarbonates at the cost of a relatively lower pH. We observe the breakdown of Donnan exclusion effects with higher ionic strength electrolytes which allows diffusion of both co-ions and counter-ions, promoting the bicarbonate reactions. Further, we find that the pKa of Nafion® generally increases as the local dielectric constant of the reaction medium decreases. This is primarily due to the accumulation of K+ and production of low dielectric constant products such as ethanol, albeit their concentrations are low on planar Cu electrodes. The lower permittivity of the reaction medium weakens the exclusion forces and changes the morphology of Nafion® which ultimately impacts its ability to mitigate homogeneous bicarbonate reactions.

Colorimetric and absorbance based sensor for sulfide and bicarbonate ions by dye doped polymer composite

We have developed a simple, rapid and cost-effective Dual-channel “colorimetric and absorbance” sensor using polyvinylpyrrolidone (PVP) capped Rhodamine6g (Rh6G) dye composite. Dye-doped polymer composite probe (PVPRH) exhibit intense, narrow absorption properties and long-term stability than the bare Rh6G. The probe’s colorimetric relationship with pH was demonstrated by absorption titration. The PVPRH provides a sensitive dual channel method for the determination of sulfide and bicarbonate with colorimetric response and absorption quenching. The synthesized probe, as a two-faced, exhibited remarkable colorimetric responses from orange to pale yellow in the presence of S2- and orange to soft pink in the presence of HCO3- ion, which can be observed by the naked eye also. Under optimal conditions, the relative absorption intensity decreases with increasing ion concentration of sulfide and bicarbonate ions. This trend is observed within the probe solution concentration range of 5 mM to 50 mM. The Dye-doped polymer composite probe is easy, cost effective, rapid, and has real time detection capability for sulfide and bicarbonate ions. The composite probe is stable and optically modified and can be successfully used for detections of S2- and HCO3- ions as strip senor.

Оцінка сучасного гідрохімічного стану деяких рибогосподарських ставів Київщини

Purpose. To assess the quality of the hydrochemical regime of fishponds, the territory of which suffered massive missile strikes or was directly a combat zone or close to the front line. Methodology. Chemical parameters of water including the content of ammonium nitrogen, nitrites, nitrates, phosphates and total iron were measured by the photometric method, while chloride concentration of chlorides by the argentometric titration method. The hydrogen indicator (pH) was determined electrometrically, and sulfate content and mineralization by the gravimetric method. All the above-mentioned methods are generally accepted in the comprehensive assessment of the ecological state of fishponds. Findings. The total amount of mineral salts dissolved in water was studied and analyzed in laboratory conditions, namely: the concentrations of calcium, magnesium, chlorine, bicarbonate ions and sulfate ions. The determined permanganate oxidizability in the investigated ponds exceeded the normative values by 72, 49, 31, and 42%, respectively. The concentration of nitrates ranged from 19.96 to 6.34 mg N/dm3, nitrites from 0.33 to 0.11 mgN/dm3, which indicates the intensity of decomposition of organic substances and indicates a certain degree of contamination of ponds. The amount of total iron in the studied ponds ranged from 1.98 to 1.17 mgFe/dm3, respectively. A slight increase in mineral phosphorus in ponds No. 1 and No. 2 was established by 31 and 26%, respectively, which can probably be related to both the decomposition of zooplankton and the input of pollutants from the outside from the surrounding areas. The obtained results of the laboratory analysis of the chemical composition of water samples as well as their comparison with the normative values for water bodies used for aquaculture provide a basis for assessing the current hydrochemical state of the investigated ponds of Kyiv region Originality. For the first time, a hydrochemical analysis of fishponds in Kyiv Region was conducted, the territory of which suffered massive missile strikes or was directly a combat zone or close to the front line. Practical value. The obtained results will contribute to a better understanding of the current ecological state of fishponds in Kyiv region. Keywords: water body, chemical analysis of water, toxic substances, ecological condition.

Physico-chemical quality of tap water in an urban environment: The case of the Massengo district, arrondissement n°9 Djiri, Brazzaville

The drinking water supply in the Massengo Soprogi district in Brazzaville's Djiri 9 arrondissement is provided by the Djiri river, whose mineralization dictates that of the water in the distribution network. Tap water in this district was analyzed for various parameters in order to understand the acquisition of mineralization. The physico-chemical analysis of these water samples showed that the water has very little mineralization, and is not very hard due to the geological nature of the Djiri riverbed (sandy soil). The pH values in the wet and dry seasons give the water a weakly acidic nature and, taking into account the concentration of bicarbonate ions, a low level of complete alkalinity. The geochemical processes responsible for this mineralization are mainly: water-rock interaction and ion exchange, and silicate dissolution. The geochemical methods used were the Gibbs diagram and the calculation of a few characteristic ionic ratios. Tap water has a strong aggressive and corrosive tendency, as revealed by Langelier's saturation index and Ryznar's stability index.