Composition Of Water Research Articles

Nuclear Magnetic Resonance and Computational Studies of Sodium Ions in an Ionic Liquid/Water Mixture.

We report a computational protocol for simulating electric field gradient dynamics around Na+ cations in mixtures of 1-ethyl-3-methylimidazolium tetrafluoroborate ([Im21][BF4]) and water validated by comparison to measurements of nuclear magnetic resonance (NMR) T1 relaxation times. Our protocol combines classical molecular dynamics simulations of a scaled charge model of [Im21][BF4] and TIP4Pew water to generate the electric field gradient (EFG) correlation function, CEFG(t), with quantum chemical calculations for determining the EFG variance . Although we demonstrate that the Sternheimer approximation is as valid in these mixtures as it is in neat water, we do not recommend using the Sternheimer approximation as it underestimates by ∼10% compared to a set of computationally efficient density functional theory calculations. Our protocol is capable of reproducing both the composition- and temperature-dependence of T1 over the full range of experimentally accessible [Im21][BF4]/water compositions and a temperature range of 285-350 K. We also show that scaling the [Im21][BF4] charges does not simply speed up the dynamics of the solvent, but has effects on the shape of CEFG(t). Following validation of our protocol, we analyze the shape and relaxation times of CEFG(t) to show that the mechanism by with T1 changes is different when the composition of the mixture varies compared to changes in temperature. As composition changes, the balance between inertial and diffusive relaxation alters, whereas temperature only affects the time scale of the diffusion portion of the relaxation. We also show that solvation shell of Na+ in these mixtures is significantly more labile than in neat [Im21][BF4] and that water and BF4- anions compete to be in the Na+ solvation shell. This validated computational protocol opens the door to more detailed interpretation of NMR T1 relaxation experiments of monatomic ions in complex liquid environments.

Relationship Between the Feeding Habits of Chlamys farreri and the Community Structure and Abundance of Phytoplankton in the Yellow Sea

Filter-feeding shellfish primarily rely on suspended particles in the surrounding waters for nourishment. This study aims to understand the potential food sources for Chlamys farreri in the Yellow Sea off Long Island, Shandong Province, China, by comparing the phytoplankton composition in the aquaculture waters with the stomach contents of the scallops. The abundance of dominant species in the aquaculture waters exhibited significant shifts between summer and autumn. Key environmental factors influencing phytoplankton abundance included salinity and nutrient levels. Notably, there were differences in the types of phytoplankton that C. farreri could filter and consume, displaying a marked preference for 17 distinct phytoplankton species during foraging. The proportional similarity observed in summer suggested that C. farreri feeding behavior was selective and not influenced by the surrounding phytoplankton community. Diatom phytoplankton dominated both the aquaculture waters and the stomach contents of the scallops, while only minimal amounts of Dinoflagellates, Cyanophyceae, Chlorophyceae, and Chrysophyceae were found in the stomach contents. This relationship between marine phytoplankton and the stomach contents of the scallops provides foundational data for enhancing aquaculture yields of C. farreri.

Geochemical and Thermodynamic Study of Formation Water for Reservoir Management in Bibi Hakimeh Oil and Gas Field, Iran

This research evaluates the mineral ions and their concentrations in formation water from five well samples of the Bibi Hakimeh oil field (Iran). The analysis reveals the presence of calcium (Ca2+), sodium (Na+), and magnesium (Mg2+) cations, as well as sulfate (SO42−), bicarbonate (HCO3−), and chloride (Cl−) anions, which are soluble in water within the Bibi Hakimeh oil formation. Furthermore, mineral deposits of CaSO4, CaSO4.2H2O, CaCO3, and MgCO3 are investigated and predicted using StimCADE 2 software. The findings highlight the significant chemical precipitation of calcium sulfate and calcium carbonate mineral deposits under the operating conditions of the Bibi Hakimeh oil well. The geochemical composition of the formation waters is discussed to understand the equilibrium conditions and possible influence of the physical parameters. Additionally, this study examines the interaction between rock and water of the Bibi Hakimeh formation, revealing a notable correlation between the concentration of calcium and magnesium ions and the water–rock reaction in this field.

Polystyrene nanoplastics are unlikely to aggregate in freshwater bodies.

The fate and toxicity of nanoplastics (NPs) in the environment is largely determined by their stability. We explored how water composition, nanoplastic size, and surface carboxyl group density influenced the aggregation of polystyrene (PS) NPs in fresh water. Unfunctionalized 200, 300, 500, and 1000nmPS NPs and 310nm carboxylated PS NPs with carboxyl group densities of 0.35 and 0.6mmolg-1 were used to simulate pristine and aged NPs. Natural water matrices tested in this study include synthetic surface water (SSW), water from the Schie canal (Netherlands) and tap water. Suwannee River Natural Organic Matter (SRNOM) was included to mimic organic matter concentrations. In CaCl2, we found PS NPs are more stable as their size increases with the increase of the critical coagulation concentration (CCC) from 44mM to 59mM and 77mM for NP sizes of 200nm, 300nm and 500nm. Conversely, 1000nmPS NPs remained stable even at 100mM CaCl2. Increasing the carboxyl group density decreased the stability of NPs as a result of the interaction between Ca2+ and the carboxyl group. These results were consistent with the mass of Ca2+ adsorbed per mass of NPs. The presence of SRNOM decreased the stability of PS NPs via particle bridging facilitated by SRNOM. However, in SSW, Schie water and tap water with low divalent cation concentrations, the hydrodynamic size of PS NPs did not change, even at prolonged durations up to one week. We concluded that PS NPs are unlikely to aggregate in water with low divalent cation concentrations, like natural freshwater bodies. Ecotoxicologists and water treatment engineers will have to consider treating PS NPs as colloidally stable particles as the lack of aggregation in fresh surface water bodies will affect their ecotoxicity and may pose challenges to their removal in water treatment.

Stable isotope composition of surface waters across the Pamir, Central Asia: Implications of precipitation seasonality

Stable isotope composition of surface waters across the Pamir, Central Asia: Implications of precipitation seasonality

Bark water affects the isotopic composition of xylem water in tropical rainforest trees

The movement of water between xylem and inner bark (phloem and associated tissues), mostly driven by water potential differences, forms a key part of the diel transpiration cycle. It is not known how the use of water stored in bark at the diel transpiration cycle may influence the isotopic composition of xylem water. Understanding these possible effects is a major challenge for the identification of tree water sources and the interpretation of water use patterns using isotopes. Here, we examined the variation in the isotopic composition of water in inner bark and xylem at the diel scale and assessed how this varied in relation to traits and water use strategies on nine tree species in a tropical rainforest at the end of the dry season. We measured δ2H and δ18O in bark and xylem at two shallow depths: ‘outer xylem’ and ‘inner xylem’ (up to ~0.5 cm and ~ 1 cm from inner bark, respectively) collected at predawn, morning and midday. Considering all species together, the average isotopic composition of water in bark and outer xylem was similar at predawn and midday, suggesting water exchange between these tissues was reflected at these times, but differed significantly in the morning during increased transpiration. Results suggest that bark-xylem water exchange throughout the diel transpiration cycle affects the isotopic composition of xylem water in tropical rainforest trees. Furthermore, variations in δ2H and δ18O between xylem and bark were more pronounced in a deep-rooted, more isohydric species with dense wood than in a shallow-rooted, more anisohydric species with low wood density. This may suggest differences related to traits and hydraulic strategies in the reliance of bark-stored water across the diel cycle to buffer changes in xylem water potential. We discuss implications for interpreting tropical tree water sources in relation to water use strategies.

Humic substances modulate bacterial communities and mitigate adverse effects of temperature stress in coral reef organisms.

In the present study, we tested if terrestrially-derived humic substances (HS) could mitigate the adverse effects of elevated temperature and UVB radiation on the bacterial communities of two hard corals (Montipora digitata and Montipora capricornis), one soft coral (Sarcophyton glaucum), sediment and water. We also examined the impact of temperature, UVB radiation and HS supplementation on coral photosynthetic activity, a proxy for coral bleaching. We performed a multifactorial experiment using a randomized-controlled microcosm setup. Coral photosynthetic efficiency was measured in vivo using a pulse amplitude modulation (PAM) fluorometer. Bacterial communities were analyzed using 16s rRNA gene sequencing. Corals in HS-supplemented microcosms had significantly higher photosynthetic activities than those in microcosms subjected to elevated temperature and UVB radiation. Additionally, HS supplementation significantly influenced the composition of sediment, water and host-associated bacterial communities. Reef organisms in HS supplemented microcosms contained distinct bacterial communities enriched with groups of potentially beneficial bacteria. In the hard coral Montipora digitata, we observed an interactive effect of HS supplementation, UVB radiation, and temperature. Our findings indicate that HS significantly modulates coral reef bacterial communities and support the hypothesis that these substances contribute to improved reef resistance to the adverse effects of elevated temperature and UVB radiation.

АНАЛИЗ И ОЦЕНКА КАЧЕСТВА ПОВЕРХНОСТНЫХ ВОД БАССЕЙНА РЕКИ ЕЛЕК В ЗОНЕ ВОЗДЕЙСТВИЯ ТЕХНОГЕНЕЗА

The article provides an overview of anthropogenic factors negatively affecting the geosystems of the Ilek River basin. The accumulation of chemical elements and their introduction into the environment result from human industrial and agricultural activities. The article examines natural and anthropogenic causes that adversely impact the qualitative composition of surface waters in the Ilek River basin. It also considers the hydrological regime of the Ilek River and its major tributaries based on field observations conducted in 2024. The study identifies natural and anthropogenic factors that have been influencing the geosystems of the Ilek River basin for decades. Results of chemical analyses of surface water samples from key sites demonstrate a clear correlation with elements of the technosphere. It has been established that first- and second-order tributaries of the Ilek River, located in the northeastern part of the basin, are polluted with heavy metals due to mining and geological exploration activities. The Water Pollution Index (WPI) was calculated for the Ilek River and its major tributaries. The findings indicate that while the water bodies of Aktobe oblast, which remain underresearched, generally meet surface water quality standards, the surface waters in the middle reaches of the Ilek River are classified as highly polluted. This highlights the necessity for more comprehensive investigations to prevent further deterioration and to develop measures for reducing pollution levels.

The current ecological state of the Kurgan region lakes systems and the prospects of their use in the fishery of biological resources

One of the conditions of contracts concluded with users for industrial fishing is the planned volume of breeding (cultivation) of aquatic biological resources. To justify a biomass, it is necessary to take into account the phase of the hydrological cycle of lake ecosystems, the degree of overgrowing with macrophytes, the dynamics of the food supply, the chemical composition of natural waters, and seasonal concentrations of oxygen dissolved in water. The recommendations for the biomass of aquatic biological resources breeding take into account the dynamics of the water level since 2006. If it maintained, it is possible to stabilize and increase the growing biomass and commercial fishing in polyculture. This is an annual cultivation of Coregonus peled with the simultaneous use of Cyprinus carpio, Hypophthalmichthys sp, Ctenopharyngodon idella and other fish species in a long-term cycle. However, changes in the hydrological regime of reservoirs in the last 5–6 years and the superimposed critical weather conditions of the last three years have reduced this indicator to a minimum, and sometimes made it impossible to achieve it in many lakes of the Kurgan Region. In many fishing and fish-breeding areas of the region, as result of the decrease in the water level, their depth has decreased by 1.0–1.7 m with an increase in mineralization to a critical level for populations of introduced fish species. Shallower lakes today represent separate shallow areas of water with the general drying up of the reservoir bed. It is possible to preserve them for tenants if they not used for several years until the possible restoration of the ecological situation only with legislative and judicial consolidation of the conditions for the occurrence of force-majeure situations.

Stable H–O and radiogenic Sr isotopic ratios in bottled water in South Korea

ABSTRACT Stable H–O and radiogenic Sr isotopic compositions of bottled water in South Korea were investigated to trace water origins and to elucidate hydrogeochemical water–rock interactions within aquifers. Eighty-one bottled water samples were collected across the country. The δD and δ18O values, and 87Sr/86Sr ratios and Sr contents of groundwater-sourced bottled water samples were in the ranges of −68 to −40 ‰, −10 to −7 ‰, 0.7050–0.8112, and 14–400 μg L−1, respectively. The corresponding ranges for desalinated deep-ocean water samples were −1.2 to 1.6 ‰, −0.35 to 0.10 ‰, 0.7078–0.7092, and 12–407 μg L−1, respectively. Isotopic compositions indicate spatial variations in stable isotopic signatures with geographical location, while Sr isotopic ratios are correlated with the geological characteristics of water sources. Oxygen isotopic compositions of bottled water show a negative correlation with latitude, while Sr isotopic ratios vary with aquifer geology. The integration of stable and radiogenic isotopic compositions improves our understanding of water–rock interactions, enabling accurate authentication of water sources.

The Effect of Drinking Ionized Water on the Productive Performance, Physiological Status, and Carcass Characteristics of Broiler Chicks.

Water treatment technologies have received great attention recently, as water is the most important nutritional element, and animals consume it daily in larger quantities than those of food. The ideal water treatment affects the chemical composition and physical properties of water, having a significant positive impact on the animal's physiology, productivity, and welfare. Studies conducted on water ionization devices for broiler chickens remain limited; therefore, this study was planned to investigate the effect of ionized drinking water on the productive performance, physiological status, and carcass characteristics of broiler chicks. A total of 900 one-day-old broiler chicks were randomly and equally assigned to three groups, each with six replicates (50 birds/replicate). The first group (C) received tap drinking water and served as a control, while the second group (T1) received ionized drinking water from an ionizing device that worked for 1 h/100 L. The third group (T2) received ionized drinking water from an ionizing device that worked for 2 h/100 L. Water analysis for each treatment was performed. Productive traits, such as weekly body weight, feed intake, and water intake, were recorded. Hematological parameters and biochemical constituents were measured according to the reference's description. Furthermore, carcass characteristics, such as carcass weight and dressing percentage, and bacterial count of the intestine, such as Lactobacilli and Coliform counts, were determined. From the results, ionized water (T1 and T2) had a negative ORP, which is often desirable as it suggests the presence of antioxidant properties and lower total dissolved solids (TDSs), heterotrophic plate count (HPC), and algal total count (ATC) than in tap water. The treated chicks showed higher final body weights and better feed conversion rates than the control. Ionized water also improved carcass quality characteristics, such as carcass weight and dressing percentage. T1 and T2 chicks exhibited higher hemoglobin, total protein, globulin, G and M immunoglobulin, and total antioxidant capacity (TAC) levels, as well as lower malondialdehyde (MDA) and low-density lipoprotein (LDL) levels than the control. Furthermore, they had lower pathogenic bacteria counts. Therefore, it is recommended to employ the ionizing approach for broiler chicken drinking water, particularly a 2 h/100 L ionization application, for better animal productivity, health, and welfare.

Hydrochemical Dynamics of River Flow in a Mountain River (Katun River as an Example)

It is noted that the efficiency of protection and rational use of water resources decreases due to uncertainty of information about spontaneously changing indicators of their quality, uniqueness of such variability and, consequently, due to impossibility to develop uniform rules of economic use of water bodies and watercourses. It is shown that these problems arise not only in water bodies subjected to intensive anthropogenic impact, but also in those remaining in practically natural conditions. The results of the authors' studies of the rivers of the Altai Mountains are presented, where such features of melt (freshly formed) water as structural shifts in time series of its quality indicators, clustering of volatility, non-seasonal cyclicity and long memory of time series were discovered. It was concluded that it is necessary to take into account not only external conditions but also intrinsic dynamic characteristics of water flow to assess water composition and properties in order to reliably predict its quality and ensure efficient water use.

Experimental Study of Geochemical Interaction of Carbon Dioxide With Formation Water and Rock of Water-Saturated and OilSaturated Horizons

The paper presents results of the experimental study of geochemical processes in the “formation water – CO – rock” system at reservoir conditions for waterand oil-saturated intervals of several typical terrigenous and carbonate formations of Urals-Volga region. Compositions of formation water and dissolved gas are analyzed at each stage of the experiments, as well as mineral composition of core samples before and after the interaction. Based on the experimental results, a summarizing analysis is presented of possible physical and chemical processes occurring in the “formation water – CO2– rock” system during carbon dioxide injection into waterand oil-bearing formations. The results of the experiments allow us to highlight the significant effects of dissolution and resuspension of carbonates and halite during exposure of carbonized formation water with core material of different lithology and saturation character. In a number of experiments, significant changes in the iron and sulfate anions content were recorded, indicating the interaction of the solution with pyrite and gypsum. There were no significant qualitative and quantitative differences in the results of experiments with core material from water-saturated and oilsaturated intervals of the same lithology.

Rapid screening of shellfish tainting from oil spills using an antibody-based biosensor.

Tainting of shellfish by polyaromatic hydrocarbons (PAHs) following an oil spill poses possible health risks as well as socioeconomic impacts. Traditional screening approaches for evaluating PAH contamination have limitations that can prevent timely, objective spill response decisions. The objective of this study was to investigate the relationship between PAH concentrations measured in the oyster, Crassostrea virginica, interstitial fluid using a rapid antibody-based biosensor method, with PAH concentrations in oyster tissues determined using conventional gas chromatography-mass spectrometry analysis. To accomplish this objective, bioconcentration tests were performed to simulate oil spill exposures using a crude and heavy fuel oil containing different PAH compositions. This design allowed both the PAH concentration and composition in water and, subsequently, accumulated by oysters to be varied over time. Oysters sampled during uptake and depuration phases were analyzed using biosensor and conventional analysis methods to generate comparative data. Results indicated that biosensor measurements of oysters captured the kinetics of PAH accumulation during uptake and depuration phases. Further, significant positive correlations were observed between biosensor interstitial fluid and lipid-normalized PAH tissue concentrations. However, quantitative predictions appear to be modulated by the contamination source and target analyte list for tissue analysis. Thus, the biosensor can be applied for rapidly evaluating relative PAH contamination between biota samples and offers a promising new analytical tool for oil spill monitoring and fisheries management contexts. A generic model was also developed from study and literature data to predict PAH half-lives from bivalve tissues. These predictions can help inform field monitoring of shellfish and estimate recovery times required to achieve pre-spill conditions.

Effects of tire wear particles on freshwater bacterial-fungal community dynamics and subsequent elemental cycles using microcosms.

Ecological impacts of tire wear particles (TWPs) on microbial communities and biogeochemical cycles in freshwater remain largely unknown. Here, we conducted a microcosm experiment to investigate interactions between the overlying water and sediment without and with TWPs addition in a rural vs. urban lake system. Our results revealed the degree of change in microbial community diversity in water is higher than that in sediment following TWPs addition. For bacterial communities, TWPs addition changed their composition in the water, but only little in the sediment. For fungal communities, TWPs addition changed their composition both in water and sediments. Furthermore, in water, TWPs addition increased network complexity between bacteria-bacteria, fungi-fungi and bacteria-fungi in the urban system but reduced it in the rural one. In contrast, TWPs presence did not significantly change network complexity among microbial communities in the sediment of both lakes. Isotope labeling analysis uncovered that based on a short-term (6 hours) incubation experiment, TWPs addition did not significantly change carbon nor nitrogen cycling in the water. Yet, certain changes could be observed, especially in the long-term experiment (1 month), indicating that TWPs pollution has the potential to impact elemental cycling and thus ecosystem functions by altering microbial communities. Our results provide new insights into TWPs-induced ecological effects on microorganisms and potential biogeochemical consequences in a rural vs. urban lakes.

Integrated Identification and Efficient Use of Biodiversity in Mountainous Regions

The article studies the comprehensive identification and efficient use of biodiversity (geothermal sources) in mountainous regions. Discussion of the ways to solve the most acute problems affecting mountainous regions with complex relief has always been on the agenda as a topical issue. The purpose of the presented work is to determine the quantitative, qualitative and thermodynamic parameters of geothermal sources in these territories, as well as the spatial structure of the foci of formation of their migration routes. Conducting a comprehensive assessment of the biodiversity of deforested mountainous regions substantiates the need to ensure the protection of these unique ecosystems. The issue of determining the direction of the integrated use of geothermal resources is studied not only by its structure and characteristics, but also by the level of development of complex technological processes for the extraction and processing of hydromineral raw materials and the technology of thermal energy processes. Using a number of analytical research methods (hydrogeological, geochemical, geophysical, isotope, computer (mathematical) modeling and others) to solve these problems, we determine the foci of formation of reservoir conditions in individual horizons, migration routes, as well as quantitative and qualitative parameters of thermal waters. The following issues were studied: hydrogeological research methods will help to identify the development zone of the intensive circulation aquifer (active water exchange) and the base of the development zone of the deep underground flow aquifer (impeded exchange) in the underground hydrosphere zones, and to assess their hydrodynamic and hydrothermal conditions and parameters. Based on the data from drilled exploratory oil wells, the conditions for the formation of thermal water layers in various hydrogeological structures will be determined; hydrochemical research methods will be aimed at assessing the macro- and microcomponent composition and radiation background of thermal waters at various intervals of migration routes by determining various indicators at different depths of their formation (based on the petrochemical structure of the geological part); isotopic studies of the gas composition of thermal waters will help to identify their genesis and use them as a marker when determining the points of formation; computer modeling of the underground hydrosphere of a representative object was carried out using mathematical programs.

Does Dietary Supplementation With Quercetin or Rutin Impact Growth, Stress, and Immunity in Pikeperch (Sander lucioperca) and the Water Microbial Community in Recirculating Aquaculture?

Pikeperch Sander lucioperca is a species mainly reared in recirculating aquaculture systems (RASs), but it remains very sensitive to stress and handling. Plant phenolic compounds such as quercetin or rutin are frequently investigated as feed additives to improve the growth and well‐being of fish reared in RAS, but their impact on pikeperch and RAS microbial communities has never been studied. Our objectives were to (i) test the effect of quercetin or rutin addition to feed (2.2 g kg−1 diet) on the growth, stress, and innate immunity of pikeperch reared in RAS and (ii) assess the consequence of those additives on the RAS water microbial communities. Pikeperch of 307 (±45) g starting weight were reared in nine experimental RAS (n = 3) and fed for 84 days on a diet enriched or not (control treatment) with quercetin or rutin (feeding rate: 1.5%). Considering the start (T0) and the end (T84) of the experiment, we compare the fish growth, feed conversion ratio (FCR), morphoanatomical and physiological status, and the water microbial diversity and composition through a metabarcoding approach performed on the 16S rRNA gene. Whereas no effect on fish was recorded with quercetin (624.0 ± 21.9 g final weight), rutin (558.0 ± 10.7 g final weight) reduced pikeperch growth (0.54 vs. 0.69%–0.64% day−1), and increased FCR (1.70 vs. 1.2–1.4) compared to control (622.0 ± 16.8 g final weight) and quercetin treatments, respectively. No effect was observed on all fish physiological parameters analyzed separately, but a multifactorial analysis reveals that fish fed with rutin have a different overall physiological state. Quercetin induced a shift in the microbial community structure and composition, whereas there was no effect of treatments on microbial richness or evenness. A dietary supplementation with quercetin or rutin has no or a negative impact on pikeperch growth and physiology and modifies the microbial diversity in RAS. Effects of additives being species‐dependent, precautions must be taken when formulating feed supplements, which must be based on precise studies.

Tracing nitrate contamination sources and dynamics in an unconfined alluvial aquifer system (Velika Gorica well field, Croatia).

Nitrate ions (NO3-) are one of the most common contaminants in the groundwater of the Zagreb alluvial aquifer, which hosts strategic groundwater reserves of the Republic of Croatia and supplies drinking water to one million inhabitants of the capital city. To better understand the origin and the dynamics of NO3- in the unsaturated and saturated zones, the stable isotopes of nitrogen (δ15N) and oxygen (δ18O) in dissolved nitrate, combined with physico-chemical, hydrogeochemical and water stable isotope data, were used in the current work, together with statistical tools and mixing models. The study involved monthly sampling of groundwater, surface water, precipitation and soil water samples. Additionally, the isotopic composition of total nitrogen (δ15Nbulk) was determined in solid samples representing the local nitrate sources. The combination of a nitrous oxide isotopic analyzer and the titanium(III) reduction method provides reliable measurements of δ15NNO3 and δ18ONO3, with optimal stability achieved under specific conditions. Nitrate in the study area predominantly originates from organic sources, with nitrification as the main biogeochemical process, while denitrification was identified at sampling sites under specific anaerobic conditions. Although statistical analysis can be a valuable tool, it should be applied with caution if NO3- originates from multiple sources. The isotopic composition of water showed that groundwater is predominantly recharged by the Sava River but its contribution varied spatially. The results also show the existence of a different recharge source in the southern part of the aquifer. Our findings highlighted the importance of employing a diverse range of analytical methods to obtain reliable and comprehensive understanding of nitrate contamination. By integrating multi-method approaches, stakeholders can better understand the complexities of groundwater contamination and implement more targeted measures to safeguard the water supplies for future generations.

Evaluation of Probiotic Effects on the Growth Performance and Microbiome of Nile Tilapia (Oreochromis niloticus) in a High-Density Biofloc System.

Biofloc technology is an aquaculture production system that has gained popularity with tilapia production. Probiotics provide benefits for the host and/or aquatic environments by both regulating and modulating microbial communities and their metabolites. When a probiotic feed is combined with a biofloc system, the production amount may be improved through better fish growth, disease resistance, and/or improved water quality by reducing organic matter and stabilizing metrics such as pH and components of the nitrogen cycle. Two research trials measured Nile tilapia (Oreochromis niloticus) growth performance and composition of the microbial communities in the water and within the fish fecal material, following feeding with top-coated probiotic treatments. Trial A incorporated tilapia (71.4 ± 4.4 g), and a commercial diet (Control) that was top coated with either Bacillus velenzensis AP193 (AP193; 1 × 107 CFU g1) and BiOWiSH Feedbuilder Syn3 (BW; 3.6 × 104 CFU g-1). In Trial B, juvenile tilapia (5.34 ± 0.42 g) were fed treatment diets top coated with two different concentrations of BiOWiSH Feedbuilder Syn3 at final concentrations of 3.6 × 104 CFU g-1 (BWx1) and 7.2 × 104 CFU g-1 (BWx2). Tilapia were offered commercial feed (38% protein floating tilapia feed) as a control diet for both trials. Results from both growth trials indicated no differences in growth performance due to the probiotic additions, except for feed conversion ratio (FCR) in Trial B. Both BWx1 and BWx2 showed improved survival, water quality, solids management, and bacterial composition of water and fecal matter. Even though growth performance results presented no significant differences, results could differ based on the probiotic concentration, the route of probiotic administration, or their impact on the microbial community of the biofloc system culture water. Trial results indicated that testing on a larger scale with varied probiotic doses may be necessary to achieve an effective dosage for improving tilapia growth performance.

Hydrochemical regime of some lakes of Kokshetau upland

The hydrochemical indicators of lakes Imantau, Shalkar (North-Kazakhstan region), Zerenda, Kopa (Akmola region) located on the Kokshetau upland for 2022-2023 are shown in the article. Lake Zerenda, Imantau, Shalkar - the largest water reservoir of STNP "Kokshetau". Lake Kopa is located in the center of Kokshetau, in the most urbanized area of the region. Between the studied years, there is a change in some indicators, as well as indicators exceeding the MPC. In connection with the increase in anthropogenic load on water bodies, it is important to update research annually, and hydrobiological research with hydrochemical parameters is also conducted. An increase in the amount of ammonium ions is noted in lakes Zerendа, Kopa, Imantau and Shalkar, which is a sign of pollution by organic substances. In addition, sharp changes in the chemical composition of water are observed in Lake Shalkar, where a sharp increase in mineralization is observed, which requires further studies of the state of the reservoir. The chemical composition of Lake Zerendа is relatively stable, but there is a high concentration of sodium and potassium exceeding the MPC. The levels of magnesium and calcium are also higher than normal, which indicates a higher level of minerals in the water.