Maximum Allowable Concentration Research Articles

River water quality Amudarya in territory of Karakalpakstan

The object of the study is the Amudarya River, which is the only source of water supply and domestic water use of the population of the Republic of Karakalpakstan. The studies were carried out because the Republic of Karakalpakstan belongs to the regions of ecological disaster. Therefore, work to reduce anthropogenic pollution's adverse impact on the environment is necessary. The research methods included the sampling of water from the Amudarya River in the established sections of the reservoir according to the seasons of the year for five years, 2016-2020, and the conduct of water analysis following the standard O'zDSt 951:2011 “Sources of centralized domestic and drinking water supply. Hygienic, technical requirements, and selection rules. The indicators of taste, smell, and water color in the studied sections of the Amudarya River correspond to the established hygienic standards. The concentrations of ammonium, nitrates, nitrites, sulfates, chlorides, and total iron in water do not exceed their maximum allowable concentrations. However, the concentrations of turbidity, total hardness, and mineralization of water exceed the permissible values set on them. The maximum turbidity concentrations in water are 39.0 mg/l, total hardness 10.8 mg-eq/l, and salinity 1182.0 mg/l. Based on the work results, monitoring of water quality in the Amudarya River in Karakalpakstan has been improved. This research aimed to study the long-term quality and assessment of water in the Amudarya River in the territory of Karakalpakstan.

Очистка сточных вод горнодобывающих предприятий Узбекистана с применением высших водных растений

Mining enterprises have an intense impact on the environment, and leads to its change. The sources of pollution of the most water bodies are discharged, insufficiently treated waste water from the industrial enterprises, large complexes and production waste from the development of ore minerals and mining enterprises. In the study, the general characteristics of the water in the tailings of the Central Mine Administration of GMZ-2 and the Northern Mine Administration of GMZ-3 of Mining and Metallurgical Plant were considered. For the experiment, waste water was selected from the filtrate of the CHEMIKS GMZ-3 tailings, where the dry residue is 8.1 g/l, and the water from the GMZ-3 tailing facility, where the dry residue is 8.7 g/l. The physical properties and chemical composition of GMZ-3 waste water are considered. From the results obtained, it can be seen that the waste water is heavily polluted. Based on the results obtained, the experiments were carried out with eichornia, which is the most resistant to wastewater. This plant has filtration properties, sorption, absorption and accumulation of heavy metals, reduces the concentration of chemical compounds. To study the quality of water purification from heavy metals by water hyacinth plants, water withdrawn from the tailing pond № 2 at GMZ-2, tailing pond GMZ-3 was used as a nutrient substrate. Planting was carried out on the basis of: one adult plant per liter of treated water, the water surface coverage was 75 %. Model systems were illuminated with incandescent lamps (3500 lux) at 12-hour daylight hours. The water temperature in the experiments was 22–24 °С, ambient air 24–26 °С. During the experiments, the following analyzes were carried out: water samples purified with eichornia, as well as the green mass of plants at the end of the experiments. Analysis of the content of heavy metals in the samples was carried out by atomic absorption spectroscopy. Elemental analysis of the aqueous medium was carried out by inductively coupled plasma mass spectrometry (ICP MS) on an Agilent 7500a quadrupole mass spectrometer (Agilent Technologies, USA). From the results of the experiments, it was identified that with the help of eichornia it is possible to achieve purification of more than 50 % within 10 days of 100 % wastewaters from GMZ-3, the purification efficiency can be increased to the maximum allowable concentrations of technical water in the spring and summer seasons of the year.

Assessment of annual effective dose due to inhalation and ingestion of radon from groundwater at Kantharawichai District, Maha Sarakham Province

Assessment of annual effective dose due to inhalation (Dinh) and ingestion (Ding) of radon from 43 groundwater samples at Kantharawichai District, Maha Sarakham Province using Radon Gas Monitor ATMOS 12 DPX. The results were as follows: 1. radon concentrations ranged from 1.04 – 21.87 Bq/L with a mean of 8.26±3.77 Bq/L, 2. The Dinh ranged from 2.60 – 54.69 μSv/y with a mean of 20.70±9.40 μSv/y. The Ding ranged from 0.19 – 3.94 μSv/y with a mean of 1.50±0.70 μSv/y, 3. The annual effective dose on organs, namely the dose on lungs (Dlung) ranged from 6.26 – 131.24 μSv/y with a mean of 49.60±22.70 μSv/y, and the dose for stomach (Dstomach) is 0.45 – 9.45 μSv/y with a mean of 3.60±1.60 μSv/y, and 4. The mean of excess lifetime cancer risk (ELCR×10-4) in males was 0.90±0.40 and in females, it was 0.96±0.44. The results will be compared with the action levels of various organizations, including. The maximum allowable radon concentration in water is 11.1 Bq/L, according to US EPA, and the allowable annual effective dose is 100 μSv/y, in accordance with WHO. Analysis of results can signify the health safety of radon inhalation and ingestion of groundwater from the study area.

Mathematical Modeling of the Inhibition Kinetics of Malachite Green Decolorization by Staphylococcus aureus

Basic Green 4 or Malachite Green (MG) is an important dye that found great usage in controlling fish pathogens. The use of MG has been banned but developing, and third-world countries still found applications for this dye. Bioremediation of dyes using microorganisms is on the rise. The ability to accurately predict the rate of bioremediation relies upon the gathering of the accurate rate of decolourisation, which is often inhibited at high concentrations of the toxicant. Various secondary models such as Monod, Haldane, Teissier, Aiba, Yano and Koga, Hans-Levenspiel, Webb and the Luong models were utilized to fit the specific decolourisation rate, and most of them show visually acceptable fitting except Monod and Teissier. The best model based on statistical analysis was Hans-Levenspiel with the highest value for the adjusted coefficient of determination and the lowest values for RMSE, AICc, HQC and BIC and the closest value to 1.0 for accuracy and bias factors. The Hans-Levenspiel model was found to conform to normality tests and is adequate to be used to fit the experimental data. The normality tests carried out using tests such as the Kolmogorov-Smirnov, Wilks-Shapiro and the D'Agostino-Pearson omnibus K2 test shows that the model pass the normality tests with p >0.05 for all normality tests carried out. The experimental data obtained indicates that Malachite Green is toxic and slows down the rate of decolourisation at higher concentrations. The maximum MG specific biodegradation rate (qmax), half-saturation concentration (KS), maximum allowable MG concentration (Sm), and the shape factors (n and m) were 0.136 h-1, 0.56 mg/L, 2691 mg/L, -33.31 and 35.12, respectively. The parameters obtained from this exercise can be utilized to model the bioremediation of MG in the future.

Methodical approaches to scale-up measurement of glyphosate concentration using HPLC-FLD

Introduction. Traditionally, the hygienic assessment of working conditions when using glyphosate preparations, an extremely popular herbicide in the world, is based on the use of thin layer chromatography. In this paper, alternative approaches are considered. On the basis of experimental data, the conditions for the analysis of glyphosate content in air by high performance liquid chromatography were optimized. Material and methods. All work with glyphosate solutions was carried out in polypropylene vessels. Sampling from the air medium was carried out on a medium filtration filter (“blue ribbon”). Subsequent extraction was carried out with water. The measurements were performed by high performance liquid chromatography with a fluorimetric detector at an excitation wavelength of 270 nm and an emission wavelength of 313 nm. To transfer glyphosate to a molecule with fluorimetric properties after derivatization of glyphosate in an alkaline medium using 9-fluorenylmethyl chloroformate by heating and washing off the excess of the reagent with toluene. A C18 reverse phase column was used; ammonium acetate with the addition of acetic acid and acetonitrile were used as eluents. Results. Approbation of the developed technique was carried out on real samples taken during ground treatment of fallow fields and lands of industrial territories with glyphosate preparations. The detected levels of glyphosate did not exceed the lower limit of quantitative determination: 0.5 mg/m3 in the air of the working area and 0.025 mg/m3 in the atmospheric air (with maximum allowable concentrations of 1.0 and 0.1 mg/m3, respectively). Limitations. The study considers a limited number of chromatographic columns. The study is performed on 25 model samples of the air of the working area and atmospheric air. Conclusion. Based on the results of the work performed, methodological instructions “Measurement of glyphosate concentrations in the air by high-performance liquid chromatography” were formed and sent for metrological certification in the approved manner.

Влияние минеральных удобрений на фоне последействия извести на продуктивность и свойства дерново-подзолистой почвы европейского Севера России

The studies on the efficiency of mineral fertilizers (N60P75K75) after introduction of two lime doses (1.0 and 2.0 of hydrolytic acidity value (h.a.)) were carried out during the stationary field experiment on sod-podzolic medium-loamy soil started in 1983. The authors surveyed the aftereffect of two lime doses in pure form and with annual application of mineral fertilizers. The highest yield of legume-cereal grass mixtures was obtained in the case of lime 2.0 h.a. + NPK application and amounted to 6.9 t/ha dry matter (d.m.) in 2011, 6.4 t/ha d.m. in 2021 against the control values of 3.0 and 2.4 t/ha d.m., respectively. The content of dry matter was 21.4 %, crude protein - 12.7%. The nitrate content did not exceed the maximum allowable concentration. Lime and NPK positively affecedt the agrochemical soil properties. The humus content was 2.0 %, pHKCl – 4.8 pH units, P2O5 – 208 and K2O – 140 mg/kg soil in 2021.

Potential environmental and human health risks caused by heavy metals and pathogens from illegal landfill sites in Bosnia and Herzegovina

In Bosnia and Herzegovina, several illegal waste dumps pose a significant threat to soil and water contamination. The aim of this study was to determine the levels of heavy metal contamination of soils and microbiological contamination of water near investigated landfills. The goal was to identify the harmful effects of illegal landfills on the environment and public health, as well as assessing the potential of contaminants to pollute soil and water resources. Using an Atomic Absorption Spectrometer, the amounts and distribution of four heavy metals (Cd, Co, Pb, and Cr) in soil at four illegal landfills in Central Bosnia were studied. Three water samples collected near the dumpsites studied were tested for microbes. Bacteriological analyses of water included determination of total mesophilic aerobic bacteria, aerobic heterotrophic bacteria, total coliform and fecal coliform bacteria and fecal enterococci. Quantitative results were analyzed using an analysis of variance and Tukey HSD post hoc test. Concentrations of Cd (4.96 mg/kg) and Pb (206.97 mg/kg) recorded in soil at particular sites were above the limits of maximum allowable concentration. Cr and Pb values in soil samples were relatively higher on average than that of Cd and Co. Enrichment factor and pollution load index indicated high concentration of heavy metals in soil, especially Cd. Based on these results, waste from illegal landfills may release considerable amounts of harmful metals and microbes into the environment.

Assessment of the water quality of the Volga River in the area of the Podnovsky roadstead of oil tankers for nitrogen-containing compounds

In connection with the long stay of ships in the roadsteads and the influence of pollutants on the electrical conductivity of water and the corrosion rate of structural elements of the vessel, the article assesses the quality of the water of the Volga River in the area of ​​the Podnovsky roadstead of oil tankers. The purpose of this study is to assess the content of nitrogen-containing substances in the surface and bottom layers of the Volga River in the area of ​​​​the Podnovsky raid of oil tankers and the discharge of wastewater from the Nizhny Novgorod aeration station to determine the significance of the impact of its activities on the pollution of the water use facility. In the background section, an excess of the maximum permissible concentration of ammonium nitrogen was found to be almost four times higher. In the control section, there is a significant increase in ammonium nitrogen relative to the background by 34.5%. The maximum concentrations of ammonium nitrogen are found below the wastewater discharge in the surface water layer in the range of 1.8 - 1.3 maximum allowable concentrations. The maximum concentration of nitrites exceeded the maximum permissible value by 4.8 times.

Chemical and sanitary assessment of coal spoil heaps in the south of the Kuznetsk Basin

Due to the large amount of pollution at coal spoil heaps, soil reclamation is slow and requires development and use of microbial preparations, selected based on assessments of the biochemical parameters of soil and the extent of its contamination. The material for this study was mine soils sampled in three different zones (Ka, Kb, Kc) of the Korchakol coal spoil heap. The studied sanitary and chemical indicators did not exceed the approximate permissible concentrations (APC) / maximum allowable concentrations (MAC), except for oil products (in the Ka, Kb, Kc zones, the excess averaged 2.2, 1.4, 1.2 times, respectively). The study found a direct correlation between the zinc content and the enzymatic activity of polyphenol oxidase, the level of Ni and peroxidase, as well as an inverse correlation between the As and Cu concentrations with invertase and nitrite reductase, respectively. The index of bacteria of the Escherichia coli group (coliform bacteria) in different zones exceeded the standard values by 61 and 171 times. Even though the sanitary indicators studied do not exceed permissible levels, they can slow down growth and development of plants. Thus, successful reclamation of mine soils requires introduction of biological preparations based on microorganisms that biotransform heavy metals and rhizobacteria.

A water-soluble naphthalimide fluorescent probe for Cr2O72- and Fe3+ based on inner filter effect

A probe 3 (2-ethoxy-N-(2-(2-(2-hydroxyethoxy)ethyl)-1,3-dioxo-2,3-dihydro-1H-benzo[de] isoquinolin-6-yl)benzamide) that could selectively respond to Cr2O72- and Fe3+ was reported in this paper. The selectivity, pH titration, concentration titration, detection limit, time dependence, quenching constant and recognition mechanism of probe 3 for Cr2O72- and Fe3+ were studied in CH3CN/HEPES buffer solution. The results showed that Cr2O72- and Fe3+ could rapidly quench the fluorescence of probe 3 through the inner filter effect (IFE). The quenching kept constant after 30 s, and the quenching constants were 7.99 × 103 L.mol−1 and 4.13 × 103 L.mol−1, respectively. The detection limits of probe 3 for Cr2O72- and Fe3+ were 1.15 μmol.L-1 and 1.95 μmol.L-1, respectively, which were lower than the maximum allowable concentrations in drinking water stipulated by EPA. The determination results of Cr2O72- and Fe3+ in water samples indicated that probe 3 could be used as a potential detection tool in practical applications.

Preliminary Study and Assessment of Drinking Water from Almaty, Kazakhstan

Drinking water samples from eight districts of Almaty, Kazakhstan was collected and physical and chemical analysis of the samples was carried out. Quality indicators of drinking water, such as organoleptic characteristics of water (smell, taste, color, and turbidity), general characteristics (pH, total hardness, permanganate demand, and dry residue), inorganic substances (cations and anions) and contaminants (heavy metals and total petroleum hydrocarbons) were determined, except pesticide residues which will be analyzed for further analysis with a wide range of pollutants. According to all indicators obtained for all districts of Almaty, the anthropogenic impact on drinking water in Almaty districts is assessed as low, not exceeding the permissible maximum allowable concentrations (MAC) values, and drinking water in Almaty corresponds to the approved standards and rules for drinking water of Kazakhstan. Despite of the fact that studied pollutants are below their MAC values, they still pose threat to public health due to their accumulative properties. The study of drinking water in the districts of Almaty made it possible to assess the ecological state in the studied districts of Almaty, as well as to propose recommendations for improving the quality of drinking water in areas where water quality indicators are closer to their MAC values.

The method development for elimination of matrix interferences in seawater monitoring to determine elements by ICP-MS

A simple, versatile, and economical method development with matrix elimination to determine the elements As, Ba, Cd, Co, Cr, Cu, Mn, Ni, Pb, V, and Zn in seawater by using the technique of inductively coupled plasma mass spectrometry is reported. Real seawater was used as a matrix for the standard adding calibration and other validation parameters. The samples were open digested at 80°C with 2mL HNO3 and 0.25mL HF under the hood. A two-step digestion procedure was applied, and the volume was completed to 10mL with deionized water. Chloride removal was accomplished by using this procedure. The concentrations of Ca and Mg ions were lessened by 15% and 20%, respectively. These results were verified with ion chromatography, SEM-EDS, and mass difference analyses. It was observed that there was a 40% loss in the average mass of particulate matter on the filter media after applying the two-step digestion procedure. Recovery and trueness values were in the range of 86 and 109%. The average precision amounts for elements were determined as RSD (%) in the range of 1.0% and 3.4%. The concentrations of elements determined in the 18 samples collected from the Konyaaltı Beach located in Antalya were higher than the maximum allowable concentrations of the Directive 2013/39/EU.

Characteristics of forecasting meteorological conditions of air pollution over Odesa

Formulation of the problem. The level of atmospheric air pollution in large cities is influenced by a number of factors, among which the most important are the emissions of pollutants into the air, the characteristics of the sources of admixtures, the landscape features, synoptic and meteorological conditions (Vystavnaya, Zubkovych 2014). The influence of the latter is associated with the scattering, washing out and transformation of harmful substances in the atmosphere, as well as the significant variability of their concentrations in space and time. The characteristics of the wind regime (wind direction and velocity), temperature inversions, and formation of low-troposphere currents are among the meteorological factors that most influence the concentrations of contaminants in the layer of atmosphere near the surface (Ivus 2017), (Agayar 2018) Shevchenko 2020). The purpose of the article is to develop and improve methods of forecasting meteorological conditions of atmospheric pollution over industrial areas of Odesa, as well as characterize the variability of meteorological values over the Northwest Black Sea. Methods. the data of four-time observations (01, 07, 13, 19 hours) for the main pollutants on the network of eight stationary posts for the February, April, July and October of 2011 are used as the initial materials. The catalog of typical synoptic processes over the territory of Ukraine for the period of 2011-2015 is compiled at the Department of Meteorology and Climatology of the OSENU. To clarify specific synoptic situations, synoptic maps of all levels (ground-level, AT-925, AT-850, AT-700 and AT-500) from the archive of the ARMSin (‘automatic forecaster workstation’- program for processing synoptic maps that is applied in Ukraine. Results. 1. CO concentrations in the city of Odesa increase with distance from the coastal strip in to the depth of land with maximum values in places with high traffic load, regardless of the season; 2. Absence of industrial facilities and meteorological conditions contribute to the low level of air pollution around post N 8. Exceedance of the maximum allowable concentrations of carbon monoxide is observed in 6 out of 8 observation posts; 3. Favorable conditions for the accumulation of admixtures are formed in peripheral processes with low-gradient pressure fields, in front parts of cyclones and in low-motion and small cyclones with the same air mass; 4. Temperature inversions almost always accompanied the accumulation of harmful admixtures in the ground layer of air above Odesa. Scientific novelty and practical significance. In this article we have analyzed influence of meteorological conditions on the level of atmospheric air pollution in Odesa region. For these purposes the more nuanced-based method of forecasting was adapted. We have demonstrated that its use has efficiency at the present time for improvement of operative prognostic units work for the Northwest Black Sea region. Such conclusions may be identified as a result of empirical findings.

Challenges and risks associated with impurity profiles in technical grade crop protection products produced semi-synthetically from natural products

The safety of crop protection products and their safe use is of paramount importance and requires that crop protection products are consistently marketed and used worldwide in the required registered quality. To meet these high-quality requirements, the highest demands must be placed on the production and purification of technical-grade crop protection products. In this context, impurity profiles are of utmost importance, as unknown impurities at higher than registered concentrations may pose new unknown toxicological risks to users, consumers, and the environment. Particularly high demands are placed on the production and purification of technical grade semisynthetic derivatives of fermentatively derived natural products to meet the required regulatory specifications, to ensure that relevant impurities do not exceed maximum allowable concentrations, to ensure the safe use of such products, and to eliminate any unknown product safety risks. The challenges associated with the manufacture and purification of Afidopyropen and the product safety risks associated with various qualities of technical grade Emamectin benzoate are discussed in detail.

On the issue of substantiating a high degree of one-time marginal probability of detecting pentasodium salt of diethylenetriaminepentaacetic acid in the working area

Introduction. Pentasodium salt of diethylenetriaminepentaacetic acid, which is widely used in the chemical industry as an initiator of polymerization processes, has a wide range of toxic properties. However, the normative hygienic standard for the working area in the whole wide world has not yet been established. Purpose of the study. Experimental substantiation of a large number of one-time MPC of pentasodium salt of diethylenetriaminepentaacetic acid in the environment. Materials and methods. Pentasodium salt of diethylenetriaminepentaacetic acid, CAS No. 140-01-2, outbred male rats weighing 200-240 g. Research in the field of the protection of animals used for scientific purposes (ETS N 123) is aimed at studying the protection of animals used for scientific purposes. Examinations of experimental studies on animals using generally accepted and unified methods. Statistical processing of research materials was carried out using standard application programs Statistica 10.0. Results. The mean lethal dose of diethylenetriaminepentaacetic acid pentasodium salt (DL50) for male white rats is 1702.8±228mg/kg, the acute inhalation action threshold (Limac) is the concentration of 4.62±0.4mg/m3, the irritant action threshold (Limir) - concentration 2.5±0.2 mg/m3, irritating zone (Zir) equals 2.9. Conclusion. A high one-time maximum allowable concentration of the pentasodium salt of diethylenetriaminepentaacetic acid in the environment, equal to 0.7 mg/m3, has been scientifically substantiated and experimentally found. Hazard class 2, limiting indicator of harmfulness - irritant effect. Restrictions. The authors transfer the editors of the exclusive right to natural disasters (publications), other use of the materials of the articles without citing the authors for a specific publication is strictly prohibited. Ethics. The material of the article was approved by the ethics committee at the Federal Budgetary Institution "Novosibirsk Research Institute of Hygiene" of Rospotrebnadzor (No. 2 of January 14, 2022).

Contamination and health risks of heavy metals in the soil of a historical landfill in northern China

Landfill-induced heavy metal (HM) contamination of soils is a widespread and complex problem. The levels and potential hazards of HM contamination in landfills must be evaluated before they can be reused for any purpose. In order to reuse a historical landfill in northern China, 376 sampling sites were selected in 2019 using the checkerboard layout method, and the levels of arsenic (As), mercury (Hg), antimony (Sb), copper (Cu), lead (Pb), cadmium (Cd), nickel (Ni), zinc (Zn), and thallium (Tl) in the soil were measured. Multiple evaluation methods established the HM pollution levels, agricultural suitability, and health risks associated with the sampling sites. In most parts of the study area, the concentrations of all nine HMs exceeded the screening levels and maximum allowable concentrations for agricultural soils. Only the soils in Zones 5 and 6 can be used for agricultural activity. Moreover, the deep soils were heavily contaminated with HMs in certain areas, possibly because of leaching and infiltration in the surface soil and the rise and diffusion of polluted groundwater. The soil HMs in the study area posed a higher carcinogenic risks to both adults and children. The average carcinogenic risk associated with As was 6.12 × 10−4, which was the major contributor to carcinogenic risk at all HM-contaminated sites. The results of this work empirically demonstrated that soil HM pollution is severe and problematic in the study area and remedial measures are urgently required.

Development of In-House Reference Materials for the Composition of Soils Polluted With Heavy Metals

Pollution of agricultural soils with heavy metals is an acute problem both in Russia and globally. The use of standard methods for soil monitoring is hampered by the need to regularly modernize monitoring equipment. Therefore, the development of matrix multicomponent reference materials (RM) for the composition of soils contaminated with heavy metals in concentrations exceeding their limiting values in natural soils is a highly relevant research task.To develop in-house multicomponent RMs of soil composition with the certified value of mobile forms of copper, zinc, lead, cadmium, nickel, cobalt and manganese in concentrations exceeding their trace levels.Soils for the development of RMs were collected in residential areas of the Vladimir Oblast and Chelyabinsk Oblast subjected to technogenic pollution. Samples were prepared according to a conventional methodology. The metrological characteristics of the developed RMs were determined by the method of interlaboratory comparison with the participation of 59 accredited testing laboratories. The mobile forms of heavy metals were determined by the atomic absorption method. An assessment of the error and uncertainty of the certified RM value was performed.Two in-house RMs of the composition of soils containing mobile forms of copper, zinc, lead, cadmium, nickel, cobalt and manganese at the level of tens of maximum allowable concentrations were developed. The developed RMs were found to be homogeneous in terms of all certified indicators. The calculated error did not exceed admissible values. The shelf life of RM samples was determined to be two years.The developed in-house RMs can be used for supporting agroecological monitoring and research programmes.

Контроль вмісту нітратів у харчових продуктах – актуальні питання

Abstract. Nitrates are natural metabolic products of all plants. They are vital to plants – without them their normal growth and development is impossible. However, the uncontrolled use of nitrogen fertilizers has led to their uncontrolled accumulation in food products. When eating vegetables with high amounts of nitrates, they are partially restored to nitrites in the intestinal tract, and the latter, entering the bloodstream cause diseases – methemoglobinemia. Therefore, quantitative and qualitative determination of nitrates and nitrites in plant and animal products, water and soils are relevant today. Based on the analysis of scientific literature, the essence of the problem of excessive accumulation of nitrates in agricultural products and their negative impact on human health is highlighted. Aim. The aim of the research was to determine experimentally the concentration of nitrates and nitrites in plant and animal products, water and soils, to compare it with the maximum allowable concentration as required by Commission Regulation (EU) No 1258/2011 on maximum nitrate content in vegetables and by State sanitary rules and regulations on Maximum Permissible Levels of Certain Contaminants in Food, approved by the Order of the Ministry of Health of Ukraine of May 13, 2013 No 368 (as amended by the order of the Ministry of Health of Ukraine of May 22, 2020 No 1238). Materials and Methods. Sources of information retrieval in printed and electronic publications, databases search engines, methods of analysis, comparison and generalization of data. Photometric method. Results. The analysis of the value of nitrates in nature, sources of this substance in food was conducted; normalization of the content of nitrate components, the problem of plant products quality decline due to the uncontrolled use of fertilizers was studied; the content of nitrates in plant and animal products; the harmful effects of products with high nitrate content were considered; a comprehensive assessment of nitrate content in plant products was carried out; comparative characteristics of methods for determination of nitrate compounds were given; the consequences of consumption of products with high nitrate content were analyzed. Conclusions. The problem of nitrate pollution is becoming increasingly significant, because the amount and speed of the nitrate nitrogen cycle in the environment is constantly increasing, which increases its impact on natural systems and the possibility of nitrate accumulation in crop products, humans and animals. Therefore, the implementation of analytical control of food and environmental objects is important to obtain objective information about the content of man-made pollutants, which are nitrates and nitrites. Key Words: nitrates, maximum permissible level, nitrate compounds, nitrate pollution.

Numerical investigation of a photovoltaic module under different weather conditions

In this study, a numerical investigation of the uncooled polycrystalline concentrated photovoltaic (CPV) module was established using ANSYS software. The main objective is to estimate the maximum allowable solar concentration ratio (CR) at which the CPV module can safely operate without overheating. The numerical model was validated using data from the literature, resulting in a very good agreement. The thermal and electrical performance of the CPV module was studied at different ambient temperatures (0, 10, 20, 30, and 40 °C), wind speeds (1, 2, 3, 4, and 5 m/s), and CR number of (1.0,1.5, and 2.0 suns). This smaller CR can be achieved using a compound parabolic concentrator (CPC). The CPV system can safely operate when CR ranges from 1.0 to 1.5 suns, (1 Sun = 1000 W/m2), at all studied values of ambient temperatures and wind speeds. However, increasing the CR up to 2.0 makes results in a safe operation at wind speed values from 3 to 5 m/s. Further, the electrical efficiency increases rapidly by increasing the wind speed from 1 to 2 m/s and this increase gradually drops by growing the wind speed from 3 to 5 m/s. Furthermore, the minimum solar cell efficiency reached 12.56% at CR of 2.0 and 1 m/s. The highest heat dissipation from the CPV module is occurred at the lower ambient temperature and gradually decreases as wind speed rises.

Hygienic regulation of various water types at the present stage

Introduction. In 2019-2020 as part of the implementation of the “regulatory guillotine” mechanism, there was revised or canceled a number of regulatory requirements including those related to the rationing of various types of water. The purpose of the work was to eliminate outdated requirements that do not meet modern conditions for ensuring sanitary and epidemiological well-being in the field of water use of the population. Materials and methods. The research materials in the field of hygienic regulation of waters were sanitary rules and norms for drinking, domestic and cultural water use, maximum allowable concentrations (MAC) and approximate permissible levels (APL) of chemicals in the water of water bodies for domestic drinking and cultural water use. Results. There were approved two interrelated documents including SanPiN 2.1.3684-21 and SanPiN 1.2.3685-21, in which the requirements for the main types of water are systematized. The revised and updated documents exclude provisions of a descriptive nature, methods and technologies for implementing mandatory requirements. A distinctive feature of the hygienic requirements for water was the use of the error value of the method for determining substances in assessing the compliance of pollution levels with hygienic standards. Hence, the requirement for metrological support of determination methods is mandatory. The standards included in SanPiN 1.2.3685-21 are harmonized considering international data, including WHO, and health risk assessment. On the base of these approaches in section III, concerning water hygiene standards, twenty one standard was harmonized by chemical factor, of which 7 were modified, 5 standards were added considering WHO recommendations, 8 - considering EU recommendations (hormones and antibiotics), 1 - considering recommendations of Uniform sanitary rules of EurAZEU, standards of 69 pesticide active ingredients that are listed in Section IX containing pesticide guidelines were excluded. In addition, the list of APLs includes standards for 9 new substances that were reviewed and approved by the Commission on State Sanitary and Epidemiological Regulation. Limitations. The limitations of the study are related to the fact that the changes and additions made to the sanitary and epidemiological requirements for various types of waters are not exhaustive and can be revised as the standards of new substances, data on the toxicity and danger of standardized compounds, modern water treatment technologies and expansion of water uses become available. Conclusion. The implementation of the principles of elimination of excessive regulation and harmonization of standards with international requirements made it possible to unify the system of hygienic standards for various types of water.