Increasing Water Hardness Research Articles

GROUNDWATER POLLUTION SOURCE USING PRINCIPAL COMPONENT ANALYSIS IN GUELMA PLAIN, NORTHEAST ALGERIA

This study was conducted in the agricultural region of Guelma, located in northeastern Algeria, where groundwater is the main source of water for human consumption, agriculture, and industry. The objective was to characterize groundwater quality and identify potential pollution sources using multivariate statistical methods, including Principal Component Analysis (PCA), correlation matrix, and the Piper diagram. The analyses revealed strong correlations between certain ions, such as sodium and chloride, suggesting carbonate dissolution processes, such as calcite and dolomite, leading to increased water hardness. The Piper diagram allowed for the classification of water types based on the relative concentrations of major cations (Ca²⁺, Mg²⁺, Na⁺+K⁺) and anions (Cl⁻, SO₄²⁻, CO₃²⁻+HCO₃⁻), showing a predominance of mixed hydrochemical types influenced by both natural and anthropogenic processes.PCA then simplified the interpretation by identifying the most influential variables that could serve as key indicators for the continuous monitoring of water quality. Overall, the results indicate that groundwater chemistry in this region is strongly influenced by human activities and local geological conditions, highlighting the need for sustainable management and continuous monitoring to protect this vital resource.

Environmental Changes of the Temirnik River in Rostov-on-Don

General Background: The increasing anthropogenic impact on river ecosystems has raised concerns about water quality and its effects on surrounding communities. Specific Background: This study focuses on the Temirnik River, located in the northern part of the city, particularly assessing pollution levels in the beaches of "Druzhba" and "Surp Khash." Historical data from 2000-2001 and recent analyses from 2017-2019 reveal significant fluctuations in chemical and biological toxicity. Knowledge Gap: While previous studies have documented pollution levels, a comprehensive comparison of historical and recent data to understand long-term changes and community impacts remains insufficiently explored. Aims: This study aims to track changes in pollution levels over time, evaluate the chemical and biological toxicity, and assess the anthropogenic impacts on the Temirnik River. Results: Chemical analysis revealed increased hardness of water due to the accumulation of calcium and magnesium sulfates and chlorides. The river, heavily impacted by untreated industrial and municipal waste, showed high toxicity levels, especially in the years 2017-2019. Bioassays using Chlorella vulgaris, Raphanus sativus, and Daphnia magna confirmed these findings. Novelty: This study provides a detailed comparative analysis of historical and contemporary pollution data, highlighting the persistent and worsening impact of anthropogenic activities on the Temirnik River. Implications: The findings underscore the critical need for ongoing monitoring and intervention to mitigate pollution. They advocate for implementing effective cleaning operations and regulatory measures to protect water quality and community health. Highlights: Increased water hardness from industrial and municipal waste. Persistent high toxicity levels impacting ecosystems. Urgent need for continuous monitoring and pollution control. Keywords: Temirnik River, chemical pollution, biological toxicity, historical data, anthropogenic impact

Water hardness affecting glyphosate efficiency for weed control and tomato (Lycopersicon esculentum L.) yield production

BackgroundThe reduced use of herbicides such as glyphosate (N-(phosphonomethyl)glycine), as an effective method for weed control in the field, is an important goal, which may be achieved by using sustainable strategies for crop production. In the arid and semi-arid areas due to the use of ground water for crop production, water hardness may affect glyphosate efficiency, which is of economic and environmental significance. Objectives and MethodsThe objective was to investigate how water hardness (0 (W1), 200 (W2), 300 (W3) and 400 mg l-1 (W4)) affect the efficiency of glyphosate (0 (G1), 100 (G2), 150 (G3), 200 g ha-1 (G4)) (0, 75, 112.5, 150 g ha-1 acid equivalent) on weed growth (Convolvulus arvensis, Malva sylvestris and Cynodon dactylon) and tomato (Lycopersicon esculentum L.) yield in the field using a factorial experiment on the basis of a complete randomized block design with three replicates. ResultsThe single and the interaction effects of water hardness and glyphosate significantly affected different weeds (158 g weed weight for W2G1, and 25.3 g for W1G4) and tomato plant measured parameters. Increasing water hardness decreased glyphosate efficiency in controlling weeds, but it enhanced plant height. Higher water hardness increased tomato leaf area, however, higher glyphosate rates decreased it. Treatments W1G2 (1617 g plot-1) and W1G4 (220.8 g plot-1) resulted in the highest and the least tomato yield, respectively. At the highest level of glyphosate, W2 resulted in the highest tomato yield, compared with the other treatments. The highest and the least plant dry weight was resulted by W4G2 (232.7 g) and W1G4 (196.8 g), respectively. ConclusionThe proper concentrations of water hardness and glyphosate may efficiently control weeds and results in optimum tomato yield in the arid and semi-arid areas.

Effects of water quality on palladium-induced olfactory toxicity and bioaccumulation in rainbow trout (Oncorhynchus mykiss).

Through emission processes, palladium (Pd) particulates from industrial sources are introduced into a range of ecosystems including freshwater environments. Despite this, research on Pd-induced bioaccumulation, uptake, and toxicity is limited for freshwater fishes. Unlike other metals, there are currently no regulations or protective guidelines to limit Pd release into aquatic systems, indicating a global absence of measures addressing its environmental impact. To assess the olfactory toxicity potential of Pd, the present study aimed to explore Pd accumulation in olfactory tissues, olfactory disruption, and oxidative stress in rainbow trout (Oncorhynchus mykiss) following waterborne Pd exposure. Olfactory sensitivity, measured by electro-olfactography, demonstrated that Pd inhibits multiple pathways of the olfactory system following 96 h of Pd exposure. In this study, the concentrations of Pd for inhibition of olfactory function by 20% (2.5 μg/L; IC20) and 50% (19 μg/L; IC50) were established. Rainbow trout were then exposed to IC20 and IC50 Pd concentrations in combination with varying exposure conditions, as changes in water quality alter the toxicity of metals. Independent to Pd, increased water hardness resulted in decreased olfactory perception owing to ion competition at the olfactory epithelium. No other environmental parameter in this study significantly influenced Pd-induced olfactory toxicity. Membrane-associated Pd was measured at the olfactory rosette and gill following exposure; however, this accumulation did not translate to oxidative stress as measured by the production of malondialdehyde. Our data suggest that Pd is toxic to rainbow trout via waterborne contamination near field-measured levels. This study further demonstrated Pd bioavailability and uptake at water-adjacent tissues, adding to our collective understanding of the toxicological profile of Pd. Taken together, our results provide novel insights into the olfactory toxicity in fish following Pd exposure. Integr Environ Assess Manag 2024;20:1407-1419. © 2024 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Ефективність вирощування молоді осетрових (Acipenseridae) видів риб за різної твердості води

Ефективність вирощування молоді осетрових (Acipenseridae) видів риб за різної твердості води

Investigation of the Physical and Chemical Properties of Underground Water in Kabul City

The objective of this research is to assess the quality of underground water in Kabul city in terms of health and compliance with WHO and other relevant standards. To evaluate underground water quality in Kabul city, 25 water samples are collected from various locations. Advanced instruments such as the HQ440d Multi-Meter, Turbidity Meter, Conductivity Meter, and Wag-WE10500, along with reagents like Alkali Solution and Calcium and Magnesium indicator Solution, are used to measure different chemical and physical parameters of the water. Various tests are conducted in the field and laboratory. Chemical parameters including bicarbonate, sodium, magnesium, calcium, iron, fluorine, potassium, chlorine, chloride, arsenic, and nitrate are evaluated. Some parameters, such as fluoride, iron, arsenic, sodium, potassium, and chlorine, are within permissible limits for underground water in Kabul. However, findings confirm previous concerns about deteriorating water quality, including increased water hardness and nitrite levels. Parameters such as chloride, nitrite, total hardness, sulfite, and magnesium exceed permissible limits in most areas, including Kabul. Additionally, physical parameters like turbidity, conductivity, TDS, electrical conductivity, alkalinity, acidity, color, taste, smell, and temperature are assessed. All chemical and physical parameters are compared against WHO, S.EPA, ANSA, E.U, IL standards, and the results are presented in a chart for clarity. Comparisons with established standards are analyzed and discussed.

Influence of Water Hardness on Chronic Toxicity of Potassium Chloride to a Unionid Mussel (Lampsilis siliquoidea).

Elevated concentrations of potassium (K) often occur in effluents from wastewater treatment plants, oil and gas production operations, mineral extraction processes, and other anthropogenic sources. Previous studies have demonstrated that freshwater mussels are highly sensitive to K in acute and chronic exposures, and that acute toxicity of K decreases with increasing water hardness. However, little is known about the influence of hardness on the chronic toxicity of K. The objective of our study was to evaluate the chronic toxicity of K (tested as KCl) to a commonly tested unionid mussel (fatmucket, Lampsilis siliquoidea) at five hardness levels (25, 50, 100, 200, and 300 mg/L as CaCO3 ) representing most surface waters in the United States. Chronic 28-day K toxicity tests were conducted with 3-week-old juvenile fatmucket in the five hardness waters using an ASTM International standard method. The maximum acceptable toxicant concentrations (geometric mean of the no-observed-effect concentration and the lowest-observed-effect concentration) increased from 15.1 to 69.3 mg K/L for survival and from 15.1 to 35.8 mg K/L for growth (length and dry wt) and biomass when water hardness was increased from 25 mg/L (soft) to 300 mg/L (very hard). These results provide evidence to support water hardness influence on chronic K toxicity to juvenile fatmucket. However, the chronic effect concentrations based on the more sensitive endpoint (growth or biomass) increased only 2.4-fold from the soft water to the very hard water, indicating that water hardness had a limited influence on the chronic toxicity of K to the mussels. These results can be used to establish chronic toxicity thresholds for K across a broad range of water hardness and to derive environmental guideline values for K to protect freshwater mussels and other organisms. Environ Toxicol Chem 2023;42:1085-1093. Published 2023. This article is a U.S. Government work and is in the public domain in the USA.

Effects of water hardness on the flavor and antioxidant activity of Ishizuchi dark tea

Ishizuchi dark tea, a traditional Japanese post-fermented tea, has attracted considerable attention for its bioactivity. In this study, the effect of water hardness on Ishizuchi dark tea infusions was analyzed. Sensory testing revealed that the teas brewed in hard water were less sour in taste than those brewed in soft water. The most abundant organic acid found in the tea infusions was lactic acid, with a constant concentration of 4 mmol L−1, regardless of water hardness. The pH of the tea infusions increased from 4 to 5 with increasing water hardness, and a similar increase in pH was observed with increasing concentrations of Ca2+ (or Mg2+) and HCO32− in an aqueous solution of 4 mmol L−1 lactic acid. The antioxidative activity of the tea infusion was clearly independent of water hardness. Therefore, hard water is suitable for brewing Ishizuchi dark tea because tea brewed in hard water has a less sour taste, which is more favored, while maintaining the same degree of antioxidative ability.

Impacts of water hardness on coagulation-UF-NF process using aluminum salts

Surface water supplemented with reclaimed water can effectively alleviate water shortage. In this study, an integrated coagulation ultrafiltration-nanofiltration (CUF-NF) process was explored to treat reclaimed water. The effects of water hardness and different aluminum salts on the CUF-NF process were specifically investigated focusing the flocs size, membrane fouling, removal of organic matter, and disinfection by-product formation potential (DBPs-FP). Moreover, the treatment performance of two coagulants (i.e., AlCl3 and PACl25) were also compared. Results showed that the increased water hardness remarkably improved the UF membrane flux in CUF process (i.e., 51.4% to 188.3%), however, a slightly reduced flux (up to 29.5%) was noticed for NF membrane. In addition, parallel factor (PARAFAC) analysis showed that higher water hardness contributed to higher removal efficiencies of humic- (up to 40.6%) and protein-like substances (up to 60.6%), together with the reduction of total DBPs-FP (i.e., total trihalomethanes; 52.6% and total haloacetic acids; 20.4%). Furthermore, 2D-COS-FTIR also revealed the correlation between water hardness and the functional groups in UF/NF fouling layers. Overall, this work not only provides insight into the impacts of water hardness and different aluminum salts on CUF-NF processes treating surface water, but also provides new insights into the formulation of hardness standards for reclaimed water.

Prevalence and predictors of incidence of urolithiasis in a representative region

BACKGROUND: Domestic and foreign studies have shown the presence of correlations between the prevalence of urolithiasis, anthropogenic factors, and composition of the water consumed by the population. In the Nizhny Novgorod Region, there is a high incidence of urolithiasis; thus, the identification of its causes appears to be an urgent task.
 AIM: To assess the prevalence and identify predictors of the incidence of urolithiasis in the rural population of the Nizhny Novgorod Region.
 MATERIALS AND METHODS: The study was conducted in the Nizhny Novgorod Region. Annual reports of patients seeking medical care for urolithiasis for 3 years in 49 central district hospitals and two large regional hospitals were analyzed. The incidence rate of urolithiasis was calculated according to the treatment of patients with urolithiasis also for 3 years in relation to the population of each district. Information about drinking sources was obtained by questioning 800 patients with urolithiasis who were treated at the Nizhny Novgorod Regional Clinical Hospital. The chemical composition of drinking water was assessed in accordance with the requirements for drinking water SanPiN 2.1.4.1074-01. The mineralogical composition of 1000 urinary stones of patients from rural areas of the Nizhny Novgorod Rregion was retrospectively analyzed using a Nicolet iS5 IR-Fourier spectrometer.
 RESULTS: In this study, 38 (77.5%) districts of the Nizhny Novgorod Region have unfavorable conditions for urolithiasis. Moreover, 59.5% of the rural population are using water from underground sources (wells). Significant correlations were found between the incidence of urolithiasis and the chemical composition of the water consumed, particularly water hardness. The analysis of the mineralogical composition of urinary stones showed their polycomponent composition in 89.5% of the cases. Differences in the chemical composition of stones are associated with the environmental factors of the region, one of which is drinking water.
 CONCLUSIONS: Most of the rural population of the Nizhny Novgorod Region is at risk for urolithiasis. Significant differences in the incidence of urolithiasis were dependent on the degree of hardness of the groundwater used for drinking. Increased water hardness is a significant risk factor for the development of urolithiasis.

Water hardness alleviates the stress response caused by waterborne zinc in goldfish Carassius auratus

In this study, the combined effect of waterborne Zn and water hardness on the stress response in the goldfish Carassius auratus was investigated. Goldfish were exposed to Zn concentrations of 0.5, 1.0, and 3.0 mg/L and water hardness of 90, 270, and 450 mg/L CaCO3 for 1, 3, 7, and 14 d. After exposure, it was determined that higher the Zn concentration, the more obvious the stress response. However, the stress response reduced with increasing water hardness. An increase in the Zn concentration caused stress responses in fish according to the increase in the mRNA expressions of corticotropin-releasing hormone and adrenocorticotropic hormone and cortisol level in the hypothalamus–pituitary–interrenal axis. The expression of these factors was the highest on day 7 and decreased on day 14. Furthermore, to evaluate the stress change in the liver tissue, we analyzed alanine aminotransferase, aspartate aminotransferase, and heat shock protein 70 concentrations to determine the damage caused by Zn and the change in water hardness. Immunohistochemistry staining for Na+/K+-ATPase in the gills showed that the gill activity was inhibited by Zn, and an increase in water hardness could improve Na+/K+-ATPase. In conclusion, we found that increasing water hardness is a successful method to reduce the stress response in goldfish caused by Zn.

Modulating effect of elevated water hardness on growth performance, ammonia dynamics and ion-regulatory capacity in channel catfish (Ictalurus punctatus) following chronic challenge with high environmental ammonia and salinity stress

The aim of this study was to assess whether rearing fish at increased water hardness could assist channel catfish (Ictalurus punctatus) juveniles to efficiently cope with later (sub)lethal ammonia exposure or salinity stress. Fish were subjected to 100, 494 (10% of 96 h-LC50) or 1250 mg/L (25% of 96 h-LC50) CaCO3 water hardness levels for two months. Afterwards, fish were challenged with high environmental ammonia (HEA; 12.2 mg/L total ammonia ~25% of 96 h-LC50 value) or salinity stress (SST;10 ppt) separately for 21 days at their respective water hardness levels. Results show that after two months, weight gain (%), specific growth rate and feed conversion in 1250 mg/L CaCO3 group were markedly worse than 100 and 494 mg/L CaCO3 groups. This finding was accompanied with a down-regulation of hepatic IGF-I and growth hormone receptors (GHR) mRNA levels. During SST, growth was still significantly worse for those at 1250 mg/L CaCO3 (1250SST). However, exposure to HEA inhibited growth for 100HEA and 494HEA relative to 1250HEA. Ammonia excretion rate (Jamm) remained similar at different hardness levels; however, this was strongly inhibited at 100HEA, 494HEA and 100SST. This appeared to align to some degree with high water hardness having a protective effect on the gill histomorphology. In fact, fish at 1250HEA were able to increase Jamm efficiently, which was associated with upregulated branchial expression of ammonia transporters (Rhesus glycoproteins ‘Rhcg’) and Na+/H+ exchanger, as well as augmented gill H+-ATPase activity. These responses prevented a build-up of excess ammonia in plasma. In contrast, both 1250 mg/L CaCO3 and 1250HEA groups displayed inhibited branchial Na+/K+-ATPase activity indicating this unlikely has a major role in ammonia excretion. Gill Ca2+-ATPase activities reduced at the highest hardness (1250 mg/L CaCO3) and 1250HEA groups, likely to prevent hypercalcemia in plasma. No differences among hardness levels were noted for ion-regulation or Ca2+- homeostasis under SST. Overall, findings suggest that although elevated water hardness up to 1250 mg/L CaCO3 adversely affects the growth performance of channel catfish, it can ameliorate the inhibitory growth effects of HEA. This was partly attributed to 1250 mg/L CaCO3 protecting the gills as well as mitigating HEA-induced ammonia excretory and ion-regulatory disruption. However, elevated hardness may not be as effective in alleviating salinity stress in catfish.

Identification of Reactive Dye Transfer Source and Comparison of Two Types of Dye Transfer Inhibitors

The source for reactive dye transfer of cotton fabric varies in different studies, and there is limited information on the washing factors. This study explored the source of Reactive Red 195 colored cotton fabric dye transfer and reported the effects of three key washing factors and their interactions with two types of dye transfer inhibitors. First, the high-performance liquid chromatography results show that the peak of completely hydrolyzed Reactive Red 195 matches the peak of the washing residue of the fabric colored by Reactive Red 195. The dye transfer process is positively related to the hydrolyzed dyes. Based on this, response surface method models for the three factors, water consumption, water hardness, and dye transfer inhibitors concentration for polyvinylpyrrolidone and lauryl betaine were built. Both response surface method models show that due to the presence of Ca2+ and Mg2+, the increase in water hardness reduces the zeta potential on the fabric surface, and causes a decrease of electrostatic repulsion between the dye and the fabric. The dye transfer inhibiting effect is reduced. The increase in dye transfer inhibitor concentration strengthened the effect of inhibiting the transfer of hydrolyzed Reactive Red 195. In addition, there is a cross effect between water hardness and dye transfer inhibitor concentration. There is optimal water hardness and dye transfer inhibitor concentration to maximize the inhibition of hydrolyzed Reactive Red 195 dye transfer. The water consumption shows a limited effect because the washing time is long enough to reach a balance in the fabric and washing fluids. Polyvinylpyrrolidone with many hydrophilic groups is easy to combine with hydrolyzed dyes. While lauryl betaine is a small molecule surfactant, the structural differences make the response surface method model show that polyvinylpyrrolidone has a better effect than lauryl betaine. The discoveries can be used to guide dye transfer inhibitor development. Further investigations, including dye transfer inhibitor synthesis and modification, are needed.

Stream Mesocosm Experiments Show no Protective Effects of Calcium on Copper Toxicity to Macroinvertebrates.

Although the concept and modeling of metal bioavailability and toxicity have been well developed based largely on laboratory experiments with standard test species, additional evidence is required to demonstrate their applicability for macroinvertebrates typically found in natural lotic ecosystems. We conducted 10‐day stream mesocosm experiments to test the hypothesis that increased water hardness (in the present study, the calcium [Ca] concentration was increased by adding CaCl2) would mitigate the effects of copper (Cu) on natural benthic macroinvertebrate communities. Exposure of macroinvertebrate communities to 25 μg/L Cu for 10 days in stream mesocosm experiments resulted in significant decreases in total abundance, in number of taxa, and in abundance of many macroinvertebrate taxa. However, the addition of Ca to stream mesocosms and the associated increase in water hardness up to 250 mg/L CaCO3 did not mitigate these effects of Cu on macroinvertebrate communities. The results showed that the hardness‐based water quality criteria for Cu of the US Environmental Protection Agency were not protective under the conditions of relatively high hardness, low alkalinity, and circumneutral pH. In contrast, the water quality criteria based on the biotic ligand model predicted little protective effects of Ca on Cu toxicity, which is consistent with our results. Additional experiments are required to understand the influence of modifying factors on the toxicity of metals to macroinvertebrate communities. Environ Toxicol Chem 2022;41:1304–1310. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Influence of water hardness on zinc toxicity in Daphnia magna.

Zinc is an essential trace metal required for the maintenance of multiple physiological functions. Due to this, organisms can experience both zinc deficiency and toxicity. Hardness is recognized as one of the main modifying physiochemical factors regulating zinc bioavailability. Therefore, the present study analyzed the effect of hardness on zinc toxicity using Daphnia magna . Endpoint parameters were acute‐toxicity, development, reproduction, and expression data for genes involved in metal regulation and oxidative stress. In addition, the temporal expression profiles of genes during the initiation of reproduction and molting were investigated. Water hardness influenced the survival in response to exposures to zinc. A zinc concentration of 50 μg/l in soft water (50 mg CaCO3/L) caused 73% mortality after 96 h exposure, whereas the same zinc concentration in the hardest water did not cause any significant mortality. Moreover, increasing water hardness from 100 to 200 mg CaCO3/L resulted in a reduced number of offspring. Fecundity was higher at first brood for groups exposed to higher Zn concentrations. The survival data were used to assess the precision of the bioavailability models (Bio‐met) and the geochemical model (Visual MINTEQ). As the Bio‐met risk predictions overestimated the Zn toxicity, a competition‐based model to describe the effects of hardness on zinc toxicity is proposed. This approach can be used to minimize differences in setting environmental quality standards. Moreover, gene expression data showed that using the toxicogenomic approach was more sensitive than the physiological endpoints. Therefore, data presented in the study can be used to improve risk assessment for zinc toxicity.

The potential of using of alkaline earth bentonite clays of Ukraine in the production of iron ore pellets

Objective: to analyze and determine the potential of alkaline earth bentonite clays of Ukraine for use as a binder in the production of iron ore pellets. Methods: performing rheological studies of bentonite clay samples and their chemical analysis, electron microscopic studies of samples. Results: the analysis of the chemical composition and requirements for the rheological characteristics of bentonite clays used in the production of iron ore pellets at metallurgical enterprises of Russia and Ukraine is carried out. The swelling indicators and water absorption of monoionic forms of bentonites of some deposits in water of different hardness are given. The quality of pellets with bentonites, that have a different exchange complex, during an industrial water of various hardness usage is examined. The analysis of the mineralogical and chemical composition, as well as the size and composition of the exchange complex of alkaline-earth bentonite clays of the Cherkassk deposit (Ukraine), which has the largest reserves of such clays in the CIS is carried out. It is shown that clays suitable for the production of pellets are located near the surface of the earth. A comparative analysis of the strength characteristics of pellets using bentonites with an alkaline and alkaline-earth exchange complex is presented. Scientific novelty: it was shown that despite the low swelling of alkaline-earth bentonites, the quality of pellets with these bentonites, in some cases, is slightly lower, and in certain conditions is not inferior to the quality of pellets with alkaline bentonites at the same flow rate. Practical significance: for real industrial conditions it is shown that the increase in water hardness leads to partial or complete (depending on the value of hardness) replacement of alkaline exchange complex with alkaline earth and conversion of alkaline bentonite clay into alkaline earth with corresponding rheological characteristics, deterioration of lumps and the need to increase the content of bentonite in the charge. In the case of increased hardness of water in the concentrate, it is economically feasible to use in the production of alkaline earth pellets bentonite clay, if it is cheaper than alkaline.

The Study of Condition of the South Bug River Basin with Using Geoecological Methods

Purpose. Assess the current state of the Southern Bug River basin and the degree of anthropogenic impact on it (transformation) Methods. The methodology of complex field geographic research (according to S. Kurlov) was chosen for the research. On its basis, water samples were taken at the appropriate points of the river basin, which directly covered the Southern Bug River itself, as well as its tributaries, and the composition of coastal soils was analyzed. Laboratory experiments were performed on the basis of a licensed laboratory of the Uman National University of Horticulture Results. Based on the analysis of the data set of the main hydrochemical indicators of the surface water quality of the Southern Bug river basin and the analysis of the soil, it was found at some experimental points that the MPC content of the studied indicators was exceeded. The content is exceeded at all sampling points, due to the high content of complexes with humic acid salts, secondary waterlogging of reclaimed lands. The nitrite content is exceeded in the following places: r. Southern Bug (Vinnitsa and Ladyzhin), r. Ustya (Nemyriv), r. Udych litskiy district) and r. Dohna (Bershad district). The main reason for the intake of nitrates into the water is the washout of fertilizers from fields and vegetable gardens. All surface water bodies have increased water hardness, its acidity is within normal limits. The soils adjacent to the streams under consideration bear clear signs of hydrogenic accumulation of substances (carbonates, gypsum, salts) and deltaic conditions of formation (horizontal stratification, horizons buried, remnants of freshwater fauna). Conclusions. The concentration of pollutants increases with the approach of the tributaries of the Southern Bug River and the relief formed by them to their base of erosion. Excess concentrations of alkaline hydrolyzed nitrogen, as well as phosphorus and potassium compounds at the sampling points indicate a high level of intensity of the farming system, in which the use of agrochemicals is given priority. However, long-term ingress of these compounds into the water body will accelerate the process of eutrophication in the near future. The loss of humus in the soils of agricultural lands adjacent to the rivers Sob, Dokhna, Ustya was revealed. In general, the geosystem of the Southern Bug River suffers from a complex anthropogenic impact, the main source of which is agricultural production.

The effectiveness of bisulfite-activated permanganate technology to enhance the coagulation efficiency of Microcystis aeruginosa

The effects of bisulfite-activated permanganate technology (PM/BS) as a pre-oxidation process on enhancing Microcystis aeruginosa (M. aeruginosa) removal by post coagulation were investigated. The results demonstrated that pretreatment with PM/BS process effectively promoted the algae removal by coagulation with Al2(SO4)3 as the coagulant and this phenomenon was more obvious with the increase of water hardness. Compared to the sole coagulation, PM/BS pre-oxidation combing with coagulation could neutralize the zeta potential of algal cells effectively, decrease the algal cell size, and lead to the formation of more compact flocs due to the in-situ generated MnO2. The effect of oxidant dosages on algal organic matter (AOM) was also studied and no obvious release of macromolecular substances was observed with the dosage of KMnO4 increasing from 3.0 mg/L to 7.0 mg/L, suggesting the integrity of algal cells at a high KMnO4 dosage. Moreover, PM/BS pre-oxidation could lead to the decrease of most analyzed disinfection by-products (DBPs) at a Al2(SO4)3 dosage of 40.0 mg/L. The algae removal efficiency was also significantly enhanced by PM/BS pre-oxidation in the test using real algae-laden water. This study indicated that PM/BS process might be a potential assistant technology for algae removal by subsequent coagulation.

Influence of Hardness and Dissolved Organic Carbon on the Acute Toxicity of Copper to Zebrafish (Danio rerio) at Different Life Stages.

Copper (Cu) bioavailability varies under water conditions. In the present study, the whole life of zebrafish was divided into three different life stages (larvae, juvenile and adult) based on the growth curve, then the influences of water hardness and dissolved organic carbon (DOC) concentration on the acute toxicity of zebrafish were respectively investigated. The results indicated that the life stages had significant effects on Cu toxicity. The larvae stage was less sensitive to Cu than both the juvenile and adult stages. With the increase of water hardness, the toxicity of Cu on zebrafish was decreased, a linear relationship was observed between water hardness and Cu toxicity, and the same was true for DOC concentration. The results showed that taking the 24 days juvenile zebrafish to study the water quality criteria of Cu was stable, sensitive and economical.

The effect of water hardness on the toxicity of graphene oxide to bacteria in synthetic surface waters

Graphene oxide (GO), used in a wide variety of applications, is increasingly being introduced into aquatic environments; this situation calls for research on GO toxicity to assess its environmental risks. In this study, the toxic effect of GO to E.coli was studied before and after its aggregation equilibrium in the synthetic surface waters (the soft water, moderately hard water, and hard water) to reveal the effects of GO aggregation and solution hardness. The cytotoxicity of GO increased with increasing solution hardness while decreased after GO aggregation. The 3 h 50% inhibitory concentration (IC50) values of dispersed GO in the soft water, moderately hard water, and hard water were 12.2 ± 2.2, 8.5 ± 1.5, and 4.0 ± 1.0 mg/L, respectively. After 24 h shaking (aggregation equilibrium) in the synthetic surface waters, the dispersed GO aggregated and the 3 h IC50 values of GO aggregates in the three synthetic waters were 40.3 ± 6.9, 15.9 ± 2.2, and 7.5 ± 1.5 mg/L, respectively. The dispersed GO sheets wrapped E. coli cells and cut the cell membrane, resulting in the disruption of cell membrane and the cell inactivation. With increasing water hardness, the heteroaggregation between GO sheets/aggregates and E. coli cells was enhanced, resulting in the increase of toxic effect. The GO aggregates could also entrap E.coli cells while exhibited limited effect on cell membrane disruption without sharp edges, thereby causing the lower toxic effect compared with the dispersed GO sheets. These outcomes shed new light on the assessment of ecological effects of GO.