Maximum Concentration Limit Research Articles

Fire safety characteristics of natural gas with hydrogen admixture

The increasing pressure to decarbonise energy production leads to the need to use low or zero carbon fuels or energy carriers. One of the promising fuels of the future is hydrogen, which is carbon-free if renewable energy sources are used for its production. However, the capacity for hydrogen production is currently insufficient to make it applicable on a large scale. Adding hydrogen to natural gas allows for a reduced carbon footprint without costly modifications to pipeline distribution network. However, changing the composition of gas in transport and distribution facilities requires a thorough assessment of the impact on operational safety. Fire safety of flammable mixtures is commonly assessed on the basis of explosive limits and other parameters. Although methods are available to calculate these parameters based on the composition of the mixtures being evaluated, the final safety assessment should rely on actual measured values. The scope of this work is to determine the explosion limits of natural gas from the transit system and changes in the limits caused by the addition of hydrogen at the concentration levels of 10% and 20% (v/v). Obtained experimental results were further compared with theoretically calculated values. Attention was also paid to the change in maximum explosion pressure, maximum pressure rise rate and oxygen concentration limits (LOC). As a result, valuable data on the expansion of the explosion limits of natural gas after the addition of hydrogen are presented.

Geographic Information Systems for Water Quality Modeling in the Zhytomyr District Communities

Abstract To ensure safe and quality drinking water for residents of rural settlements who use their own wells, boreholes, and natural sources for domestic water supply, a comprehensive approach to evaluating the quality of underground drinking water using geographic information system (GIS) technologies is necessary. The purpose of the study was to assess the quality of drinking water sources of noncentralized water supply in rural settlements of the united territorial communities (UTCs) of Zhytomyr district and to create geoinformation models based on the research results. The following research methods were used during the research: analytical, field, laboratory, statistical, calculation, and cartographic. The research was conducted in 129 settlements of 12 UTCs of Zhytomyr district, where drinking water samples were collected from noncentralized water supply sources for further analysis in the Measurement Laboratory of Polissia National University, and the creation of geoinformation models using the ArcGIS Pro software package. It has been proven that the average pH level in none of the studied settlements exceeded the norm. The average nitrate concentration in the drinking water from noncentralized water sources exceeded the norm by 1.4–3.5 times, specifically in the water of the Pulyny, Cherniakhiv, Vilshanka, Volytsia, and Oliivka communities, exceeding the maximum acceptable concentration (MAC) limit by more than two times. Only in rural settlements in the Liubar community was the average iron content found to be above the norm by more than 1.9 times. Overall, it was established that the calculated value of the overall water quality class in the Zhytomyr district was 2.03, which is determined as “good,” clean water of acceptable quality. The best water quality was found in the Vilshanka, Cherniakhiv, and Stanyshivka communities, with a quality class range of 1.85–1.93, while the worst water quality was recorded in the Oliivka, Teterivka, and Liubar communities, with a quality class range of 2.13–2.31. It was determined that the highest contribution to the overall water quality was made by nitrate and iron content. The obtained research results and models based on them can be used by local governments of the studied communities to inform the population about the quality of drinking water and to develop a plan for improving the state of drinking water supply with the aim of increasing the level of environmental safety of drinking water.

Assessing the Transboundary Water Pollution Possibly Produced By an Armed Conflict

The impact of armed conflicts can be direct and indirect, highlighted by population displacement and casualties, infrastructure destruction, together with social and economic hiatus, but also the movement of air, water and soil pollutants across regional and national borders. There are numerous possible contamination sources of the water bodies and aquatic ecosystems that may appear during armed conflicts, including projectile composition, use of chemical weapons, discharge of untreated wastewater due to damage to sewage lines or wastewater treatment plants, unregulated waste management (improper disposal of industrial, hospital and municipal waste), oil spills, and deliberate poisoning of water resources. Thus, a comprehensive study from a multidisciplinary perspective of the armed conflicts is a sine qua non condition. In accordance, to properly assess the effects of pollution in the study area (Black Sea and coastal area) and to establish further strategies that can hinder the impact, water samples from various points of interest were analyzed to determine the water quality of the aquatic ecosystem and to possibly identify contaminants in the analyzed water bodies. Higher concentration values were observed for Pb in MB3 (27.9 μg/L) and Zn in MB1 (232 μg/L) and MB2 (53.1 μg/L), exceeding the maximum concentration limits set by the national legislation (10 μg/L for Pb and 50 μg/L for Zn).

RESEARCH OF ELEMENT COMPOSITION OF ARONIA MITCHURINA (ARONIA MITCHURINII SKVORTSOV & MAITULINA) LEAVES

The aim of the study was to study the composition and ability to accumulate various elements in the leaves of aronia Mitchurina for scientific rationale of the possibility of their use in medicine and pharmacy.
 The composition and ability to accumulate various elements in the leaves of aronia Mitchurina harvested in the Tambov region were studied. The elemental composition of the leaves of aronia Mitchurina and the soil from the place of plant growth was studied by inductively coupled plasma chromato-mass spectrometry. In the raw material was found 61 chemical elements, including almost all essential: macronutrients, with the predominance of calcium, potassium, phosphorus and magnesium; trace elements, with the predominance of iron, zinc, sodium, manganese.
 It was found that the ratio of elements in the soil from the place of growth and in the raw material are different. Coefficient of biological accumulation for each element were estimated, on the basis of which all elements are classified into five groups. The elements of energetic accumulation include phosphorus, and the elements of highly accumulation include calcium, potassium, and zinc. The ability of chokeberry leaves to accumulate zinc in higher concentrations (64.32 µg/g) than other species of herbal raw materials allows us to view them as a possible natural source of this element in hypoelementosis associated with zinc deficiency in the body.
 Determined in the analysis is the content of toxic elements standardized in plant raw materials: lead, cadmium, mercury, arsenic. Their contents do not exceed the maximum permissible concentration limits given in the normative documentation.

Fluoride Removal from Water Sources by Adsorption on MOFs

Fluoride is present in several groundwaters due to natural or anthropogenic origins. Although it is necessary for physiological human functions (in small amounts, i.e., 0.5–1.2 mg/L), it could be very harmful when it exceeds the maximum permissible concentration limit of 1.5 mg/L (according to WHO). Among the numerous technologies for removing fluoride from waters, metal–organic framework (MOF) materials are considered to be promising adsorbents due to their advantages of high porosity, high specific surface area, diverse functions and easy modification. In this study, the synthesis of MOFs and the progress of their application to the removal of fluoride from contaminated water, as published in the recent literature mainly over the past five years, are reviewed. The adsorption mechanism(s) and its main characteristics, such as effect of initial fluoride concentration, adsorbent dosage, solution pH, contact time, adsorption capacity, thermodynamic and regeneration studies, etc., for the removal of fluoride with the addition of different MOFs are compared. According to these comparisons, the hydrothermal/solvothermal synthesis method is most commonly used for the preparation of MOFs, whereas higher BET surface areas are shown by specific MOFs based on aluminum metal ions. The main fluoride adsorption mechanisms were found to be electrostatic attraction and/or complexation. The most common pH for conducting experiments was 7.0, but several examined materials were found to be effective over a wide pH range. Four to six regeneration cycles were successfully applied on average, regarding the MOFs under review, whereas in the majority of these cases, the sorption process was found to be endothermic.

NATURAL FORAGE LANDS OF EASTERN PODILLYA OF UKRAINE: ORIENTATION OF DYNAMIC PROCESSES AND OPTIMIZATION IN MODERN ECOLOGICAL CONDITIONS

The article presents an analysis of the state of natural forage lands of the Eastern Podillya of Ukraine. The analysis of the geobotanical survey of the natural forage lands of the Forest-Steppe of Ukraine proved that they are in an unsatisfactory state due to high anthropogenic load and need to be restored. The main sources of stress on natural ecosystems, including forage lands, are highlighted – industry, motor vehicle, sewage and household waste, as well as agricultural production, which are characterized by an excessive influx of toxic elements into the environment. Optimization of natural forage lands is an integral part of the concept of balanced development and national programs on the quality of the environment as a mandatory element of state policy. To optimize the restoration of contaminated natural forage lands, it is quite important to assess the risks from the adverse effects of heavy metals, to carry out an ecological assessment of this process, which can be the basis for large-scale measures to restore contaminated lands. Among a large number of toxic elements, heavy metals occupy a prominent place. In particular, there is an increased intake of lead, cadmium, zinc, and copper. It was found that in the conditions of dry land lowland meadows, normal dry lands are the safest and most suitable for providing herbivores with plant biodiversity. It has been proven that the accumulation of toxic substances in soils leads to their degradation, which is accompanied by a toxic effect on plants, causing a decrease in their reproductive quality. A significant man-made load of motor vehicles on the soils of the roadside space, which is accompanied by their contamination with heavy metals, was revealed. Based on the results of the research, a theoretical generalization was made and a solution to the current scientific and practical task was proposed regarding the assessment of the intensity of pollution of the natural lands of Vinnytsia region by heavy metals in the conditions of various man-made loads Installed it was found that the exceedance of the maximum concentration limit in the soils in the studied territories of local pollution of dry lowland meadows of Vinnytsia region was found only for cadmium by 1,01 times in the territories dry lands of excessive moisture adjacent to the railway connection.

On the content and control of silicon in water sources and drinking water (literature review)

Introduction. The problem of the presence of silicon in water sources and drinking water remains relevant, since there is still no sufficient understanding of the role of silicon contained in drinking water in the prevention and development of human diseases, there is no consensus on the need to establish hygienic maximum concentration limits for silicon and the feasibility of monitoring the silicon content in water. There are two opposing points of view on the effect of silicon presented in drinking water: on its definitely positive effects, and on its negative impact on human health. None of these points of view is fully confirmed and definitively proven.
 Literature Search Methods. Literature search methods on Scopus, CyberLeninka, PubMed databases: selective, analytical-synthetic, typological.
 The main part. The review provides evidence of the importance of controlling the content of silicon in drinking water. The results of a number of studies devoted to assessing the ability of silicon supplied with drinking water to counteract the toxic effect of aluminum on brain tissue, thus reducing the risk of dementia and Alzheimer’s disease, are considered. Examples are given of studying the possible relationship between silicon content in drinking water and an increase in cases of chronic kidney disease of unknown etiology (on the examples of India and Indonesia), and the data on the negative health effects of long-term drinking of silicon-containing water in the silicon province of Chuvashia. Information is also given on the content of silicon in the water of water sources and drinking water in the Russian Federation and abroad, also the currently used methods for the analytical control of silicon in water.
 Conclusion. The problem of the content and control of silicon in drinking water and water sources includes many unresolved issues, which will be considered by the joint actions of toxicologists, epidemiologists, chemists, specialists in hygiene and sanitary protection of water bodies.

Degradation and phosphorus immobilization treatment of organophosphate esters hazardous waste by Fe-Mn bimetallic oxide

Organophosphate esters (OPEs) waste is difficult to dispose effectively because of its stability and the potential risk of P element. In this study, taking one typical organic extractant of tributyl phosphate (TBP) as an example, we proposed a strategy to treat OPEs inspired by chemical looping combustion (CLC) technology—oxygen carrier immobilization process (OCIP), aiming at efficient TBP degradation and simultaneous P immobilization. Adopting Fe-Mn bimetallic oxide (FMBO) as oxygen carrier, an almost 100% P immobilization efficiency was achieved under recommended conditions which were obtained by response surface methodology. Meanwhile, gaseous products released from TBP degradation, e.g., non-methane hydrocarbon, was lower than the maximum allowable emission concentration limit. Further characterizations implied that P-species released from reaction process were mainly immobilized as stable inorganic forms of metaphosphate, phosphate and pyrophosphate. On the basis of identifying degradation intermediates, we proposed a possible degradation pathways. FMBO as an oxygen carrier provided sufficient oxygen molecules for flameless combustion of OCIP process. Electron paramagnetic resonance measurement confirmed the existence of oxygen vacancies on FMBO surface, which contributed to the formation of •O2−. Oxidation by oxygen molecules and •O2− attack resulted in the degradation and mineralization of TBP, with simultaneously achieving P stabilization.

Coagulation of trace arsenic and cadmium from drinking water using titanium potassium oxalate

Coagulation is a simple and cost-effective water treatment method that does not work well in removing multiple cationic and anionic heavy metals simultaneously from drinking water. Titanium potassium oxalate (K2TiO(C2O4)2), a fur tanning reagent, was found to be able to efficiently remove arsenite (As(III)), arsenate (As(V)), and Cd simultaneously. A dose of 120 µmol/L K2TiO(C2O4)2 could remove more than 90% of As and Cd to meet the drinking water standards when their initial concentrations were 10 times their maximum concentration limits, whereas traditional coagulants, such as Fe2(SO4)3 and Al2(SO4)3, failed to meet the drinking water standards. Additionally, K2TiO(C2O4)2 coagulation consumes natural water hardness (Ca2+/Mg2+) to produce softer water and releases healthy K+ as a by-product. The mechanism study indicated that K2TiO(C2O4)2 reacted with natural calcium ions in drinking water to form calcium oxalate, while residual titanium was hydrolyzed with water to form hydrous titanium oxide. Arsenic was removed primarily via complexation with hydrous titanium oxide, while Cd was removed via the combined effect of adsorption by hydrous titanium oxide and mixed-crystal formation by calcium oxalate. This study provides an efficient coagulant for removing multiple heavy metals simultaneously, which can be applied in water treatment to provide safe and healthy drinking water.

Terrestrial animal livers as a source of PCDD/Fs, PCBs and PBDEs in the diet

The livers of terrestrial animals are an important source of vitamins and minerals, but with the liver being the major filtering and detoxifying organ, it retains xenobiotic material, especially persistent organic pollutants (POPs). The aim of the study was human health risk assessment related to the presence of certain POPs, namely polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) in terrestrial animals' livers. HRGC-HRMS was used to determine analyte concentrations in 99 liver samples of chicken, pork, beef, and mutton livers obtained from Polish farms. The ovine livers were the most contaminated by ∑PCDD/F/dl-PCBs (0.06–2.21 pg WHO-TEQ g−1 wet weight), ∑ndl-PCBs (0.036–1.54 ng g−1 wet weight) and ∑PBDEs (0.21–2.27 ng g−1 wet weight). Samples were found of ovine and pork livers that exceeded the maximum concentration limits established for PCDD/Fs. The Kruskal–Wallis test showed that there were statistical differences between regions in the concentrations of the ∑PCDD/Fs and ∑PCDD/F-PCBs, but none in those of the ∑dl-PCBs, ∑ndl-PCBs or ∑PBDEs. According to Dunnett's test results, ovine liver samples from the Podlaskie province contained fewer ∑PCDD/F than those from the Dolnośląskie (p < 0.027) and Małopolskie (p < 0.0342) voivodeships. Taking into account PCDD/F contents and Tolerable Weekly Intake (2 pg WHO-TEQ/kg BW) (TWI2018), the lowest risk was associated with chicken liver consumption (TWI up to 11 % in the 95th percentile), pork (62 %) and bovine (92 %) livers should be eaten in limited amounts for risk avoidance, while mutton liver (400 %) should not be eaten at all. Additionally, there is no risk of ingestion of a harmful amount of PBDEs associated with consumption of the livers of terrestrial animals from Poland based on the margin of exposure values (>15).

Hygienic aspects of the possibility of using the new insecticide seller in agriculture

According to the results of toxicological studies, it was found that the Seller preparation of 20% k.s. Belongs to hazard class III (sanpin ruz No. 0321-15). The insecticide has an irritating effect on the mucous membranes of the eyes and skin. The drug has functional cumulation. The permissible daily dose at the level of 0.72 mg (people) per day is scientifically substantiated. Seller 20% K.s. Does not have carcinogenic, mutagenic and embryotoxic effects. Based on the complex of studies, hygienic standards of the preparation were developed and recommended: maximum concentration limit in water of reservoirs at the level of 0.04 mg / l (limiting hazard indicator is organoleptic); MPC in the air of the working area - 0.24 mg / m3; MPC in atmospheric air - 0.002 mg / m3; MDU in wheat - 0.18 mg / kg; UEC in the soil - 0.2 mg / kg sanitary protection zone (C33) - 200 meters, time for going to work after 7 days. Thus, on the basis of the above, the insecticide Seller 20% k.s. Can be recommended for use in agricultural practice, subject to the mandatory use of personal protective equipment for eyes, skin, respiratory organs and compliance with the rules for the use of the drug, recommended consumption rates and safety measures when working with pesticide.The purpose of this study was to identify the danger of an insecticide. Seller is 20% ks for humans and to develop, taking into account the specific features of agriculture in Central Asia, regulations that guarantee its safety in the environment and for consumers of agricultural products in hot climates.

A pragmatic authenticity assessment of lemon (Citrus limon [L.] Burm.f.) juices by its profile of coumarins, psoralens, and polymethoxyflavones

Coumarins, psoralens, and polymethoxyflavones have long been described as authenticity markers in lemon (Citrus limon [L.] Burm.f.) juices. However, the lack of quantitative concentration limits for these markers hampers the differentiation of natural variability and acceptable technical process variations from inacceptable lacks in good manufacturing practice (GMP) or even deliberate food fraud by, e.g., the addition of lime (Citrus × aurantifolia [Christm.] Swingle; Citrus × latifolia [Yu.Tanaka]) juice. In this study, a total of 139 lemon and lime samples, including fruits, juices, juice concentrates, and peel oils from eleven countries and covering all usual processing methods on the market, were analysed using three different liquid chromatographic methods of three different labs. First, we confirmed the considered analytical approaches to yield comparable results and analysed the results in detail per product type and processing technology. After carefully eliminating samples prone to authenticity doubts, we used the remaining dataset (125 samples) for establishing maximum concentration limits for coumarins, psoralens, and polymethoxyflavones for the differentiation of authentic lemon juices produced under GMP conditions, i.e., compliant with the AIJN Code of Practice, from adulterated products made with inacceptable procedures such as excessive co-extraction of flavedo or the admixture of non-lemon Citrus species, particularly lime.

Assessment of human exposure to food crops contaminated with lead and cadmium in Owerri, South-eastern Nigeria

BackgroundFood safety and security have remained an emerging global challenge amidst increasing human activities that potentially contaminate the food chain. With the rapid population growth, urbanisation and unrestrained emission of toxic substances, urban-dwelling Nigerians are particularly vulnerable to consuming contaminated food crops. Materials and methodThis study presents a framework for critical analysis of human exposure patterns to potentially contaminated food crops using the city of Owerri (Nigeria) as case study. It systematically assessed the metal burden of soil and staple food crops and the potential health risk associated with dietary exposure of humans to contaminated food crops. Samples of soil, cassava (Manihot esculenta) tubers and fluted pumpkin (Telfairia occidentalis) leaves were collected from household gardens and analysed for concentration of selected metals (Al, As, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Ni, Pb and Zn) using ICP-OES. A risk assessment of human exposure to Pb contamination using both the Target Hazard Quotient (THQ) and Hazard Index (HI) was estimated. ResultsThe majority of metals measured below the respective health-based maximum concentration limits of the Nigerian Department of Petroleum Resources target value, except for Pb in soil, which was above the limit of 85 µg g−1 in 0.9 % of sampled soils. However, Pb measured above the threshold of 0.3 µg g−1 stipulated by the FAO/WHO Codex Alimentarius in 46 % of sampled pumpkin leaves with no correlation established with soil Pb concentrations. This suggests possible Pb contamination via atmospheric deposition, and that human ingestion of pumpkin leaves presents the greatest health risks. ConclusionThe findings revealed that children and toddlers are more prone to Pb contamination via food crop ingestion than adults based on the THQ and HI evaluations; hence need for relevant policies to ensure food safety. This study provides background data for epidemiological investigation of relationships between contaminated food crop ingestion and blood Pb.

Cadmium in the wild edible mushroom species of Agaricus bitorquis in Leicester, UK

Background and Aim: Consumption of urban garden products is increasing despite the risks that they can represent due to high urban contamination. Effects of urbanisation in wild edible mushrooms are scarce. The aim was to assess the risks to cadmium (Cd) present in wild edible mushrooms Agaricus bitorquis collected in Leicester (UK). Methods: Twenty-two A. bitorquis mushrooms were collected from an open green area close to St Augustine Road, a high traffic area within Leicester. Species identification was confirmed by DNA barcoding using internal transcribed spacer 1/4 primers after extracting DNA from 100 mg of frozen homogenised ground mushroom material using DNeasy Plant Mini Kit®. Cd was monitored by ICP-MS in cleaned, dried and homogenised mushrooms’ caps and stipes mineralised with HNO3/H2O2 [LoD=0.081 mg/kg dry weight (dw)]. Results: Cd was detected in all samples, with significantly higher levels in caps (p&amp;#x3c;0.001), median and ranges are provided in mg/kg dw: 3.878 (2.213-6.598) vs. 2.068 (0.899-3.679). Concentrations were similar to those recently reported in different species of the genus Agaricus collected in urban habitats within Berlin (Germany; &amp;#x3c;0.1-32.7 mg/kg DW), but much higher than the reported in sixteen A. bisporus (median 0.2 mg/kg DW) cultivated in high traffic areas within Berlin. All caps monitored exceeded the established maximum concentration limit for Cd in Europe (0.2 mg/kg wet weight, approximately 2 mg/kg dw), in line with the high accumulative metal capability described in the literature for Agaricus spp. Non-carcinogenic health risks in adults and children for Cd in the monitored mushrooms were 3.16E-07 and 1.47E-09, respectively. Conclusions: Our results would suggest potential contamination by Cd in the inner city of Leicester that should be further investigated to protect human health. Although non-carcinogenic risks characterised for Cd were negligible, consumption of wild edible species should be limited and substituted by cultivated mushrooms when possible.

Industrial toxicology as an important part of occupational medicine: retrospective, reality and development prospects (literature review)

Introduction. The stages of development of industrial toxicology and the contribution of the main scientific schools to the theory and practice of hygienic regulation of industrial substances in the air of the working area are considered, the main tasks for the near future are identified. Material and methods. The analysis of domestic literature, materials of scientific conferences and 25 years of experience in the section “Industrial toxicology” of the Commission “Scientific foundations of occupational health and occupational diseases” of the USSR Academy of Medical Sciences was carried out. Results. On the edge of the XX-XXI centuries, there was a significant reduction in industrial toxicology laboratories in specialized institutes, which led to a multiple decrease in the number of annual substantiation of maximum allowable concentration and indicative limit values for chemicals in the air of the working area, while maintaining a great need for this work. The lack of hygienic regulations for chemicals used in technological processes reduces the quality of a special assessment of the working conditions of workers. Against this background, due to the intensive development of the nanoindustry, in which known substances in the nanoscale acquire new properties, the chemical safety strategy becomes even more relevant. The absence of a medical specialty “preventive toxicology” complicates the quality training of relevant specialists. Limitations. The study was based on the materials of domestic publications in the open press. Conclusion. The experimental base of industrial toxicology needs to be significantly expanded, and the system of hygienic regulation of chemicals in the air of the working area needs to be optimized and transferred from initiative research to a planned distribution process.

Water pollution and environmental policy in artisanal gold mining frontiers: The case of La Toma, Colombia

Artisanal and small-scale gold mining (ASGM) is the largest anthropogenic source of mercury emissions globally. Concern over mercury pollution increases due to its long-term impacts on human health and aquatic and terrestrial ecosystems. Using a participatory research methodology, we gathered social and behavioral information regarding daily practices and water usage by an ASGM community in Suárez, Colombia. Based on this information, we identified 18 sampling sites of water sources commonly used by the community. The samples were analyzed for total mercury, total coliforms, pH, electrical conductivity, and total dissolved oxygen. Physicochemical and microbiological parameters from the water assessment were compared with the drinking water thresholds set by the Colombian regulatory agencies, the EPA, and the WHO. Our results showed that the majority of the samples do not meet one or more quality and safety standards. On average, the sampling sites showed total mercury levels below the regulatory limits; however, the data had considerable variability, and in many cases, individual observations fell above the maximum concentration limit for drinking water. We discuss these results within the larger framework of the regulatory gaps for human and environmental protection in ASGM contexts. The total lack of water, sanitation, and hygiene infrastructure, combined with the long-term consumption of sublethal doses of mercury and other water contaminants, constitutes a significant threat to the well-being of communities and territories that necessitates further research and intervention by institutional authorities.

Recent Advancements in Electrochemical Biosensors for Monitoring the Water Quality.

The release of chemicals and microorganisms from various sources, such as industry, agriculture, animal farming, wastewater treatment plants, and flooding, into water systems have caused water pollution in several parts of our world, endangering aquatic ecosystems and individual health. World Health Organization (WHO) has introduced strict standards for the maximum concentration limits for nutrients and chemicals in drinking water, surface water, and groundwater. It is crucial to have rapid, sensitive, and reliable analytical detection systems to monitor the pollution level regularly and meet the standard limit. Electrochemical biosensors are advantageous analytical devices or tools that convert a bio-signal by biorecognition elements into a significant electrical response. Thanks to the micro/nano fabrication techniques, electrochemical biosensors for sensitive, continuous, and real-time detection have attracted increasing attention among researchers and users worldwide. These devices take advantage of easy operation, portability, and rapid response. They can also be miniaturized, have a long-life span and a quick response time, and possess high sensitivity and selectivity and can be considered as portable biosensing assays. They are of special importance due to their great advantages such as affordability, simplicity, portability, and ability to detect at on-site. This review paper is concerned with the basic concepts of electrochemical biosensors and their applications in various water quality monitoring, such as inorganic chemicals, nutrients, microorganisms’ pollution, and organic pollutants, especially for developing real-time/online detection systems. The basic concepts of electrochemical biosensors, different surface modification techniques, bio-recognition elements (BRE), detection methods, and specific real-time water quality monitoring applications are reviewed thoroughly in this article.

PWC-based evaluation of groundwater pesticide pollution in the Júcar River Basin

Predicting pesticides' behavior in the environment is necessary to anticipate and minimize their adverse effects. Despite the use of pesticides in Spain is increasing, the implementation and use of predictive mathematical models is seldomly done in practice due to the lack of available data. In this original work, the Pesticide Root Zone Model version 5 (PRZM 5) mathematical model under the Pesticide in Water Concentration 1.52 (PWC) interface has been applied to model pesticide behavior in nine groundwater bodies located inside the Júcar River Basin (JRB) in Spain. Mathematical modeling allowed calculating the maximum concentration of pesticides after completing the calibration process. Bromacil, terbuthylazine, atrazine, desethyl-terbuthylazine, and terbumeton concentrations in groundwater were simulated between 2006 and 2019.Results show that the maximum pesticide concentration value on every well exceeds the current Spanish Maximum Concentration Limit (0.1 μg/L). PRZM 5 was able to reproduce pesticide concentration observations over time despite the limited amount of available data.This study contributes to assessing environmental risks caused by the use of pesticides inside the JRB and can potentially be applied in other areas of interest.

Pyrolysis of Chromated Copper Arsenate-Treated Wood: Investigation of Temperature, Granulometry, Biochar Yield, and Metal Pathways

Chromated copper arsenate-treated (cca) wood disposal faces environmental restrictions due to its toxicity, heavy metal leaching in storage sites, and greenhouse gas emissions during incineration. Thus, finding new management methods for this contaminated wood at the end of life is crucial. This study evaluated the effect of pyrolysis temperature (300, 400, and 500 °C), particle size, biochar yield, and the behavior of arsenic (As), chromium (Cr), and copper (Cu) during treated-wood pyrolysis. The highest biochar yield was obtained at 300 °C for fine particles. The biochar retention of heavy metals decreased with increasing pyrolysis temperature. At 300 °C, the highest biochar As, Cr, and Cu retentions were 76, 91, and 83%. At 500 °C, biochar only retained 43% of the As. Additionally, heavy metal leaching from the biochar exceeded the Environmental Protection Agency’s (EPA) maximum concentration limit of 5 mg/L. High-density polyethylene encapsulation of contaminated biochar reduced the leaching of As, Cr, and Cu by 96, 95, and 91%, respectively. Thus, combining pyrolysis and plastic encapsulation to produce a composite material could be a solution for reducing waste (conversion of CCA-wood into biochar) and for the safe disposal of contaminated wood.

GEOECOLOGICAL RESEARCH OF THE SOUTH BUG POOL IN THE VINNITSA REGION

The Southern Bug basin occupies most of the Vinnytsia region and flows near both industrial facilities and agricultural land. Therefore, the author based on geoecological research has developed a spatial model - a map that identifies the results and displays them within this area. Since Vinnytsia region is a region of old agricultural development, due to the significant impact of this area and due to significant intensification (using various agrochemicals) of agriculture, the quality of surface waters is deteriorating.&#x0D; The article presents the continuation of the results of the author's research and further directions of his scientific activity on the state of the Southern Bug basin and adjacent territories. According to the results of research, the author determined that the formation of sulfate ions, along with natural factors, is to some extent influenced by anthropogenic factors, especially the discharge of domestic and industrial wastewater. In the summer-autumn and winter lows the content of sulfate ions in the water of the Southern Bug increases relatively. For Cl ions, the distribution by seasons of the year is somewhat different. Thus, in the spring floods the highest values ​​are characteristic of the Udych River - 51.3 mg / dm3, their content in the water of the left-bank tributaries increases even more - from 30.7 mg / dm3 (Sob River) to 73.5 (Southern River) Bug - the village of Stavki). In general, the content of chloride ions varies less. The growth of mineralization is more noticeable in the rivers Rudka and Pivdennyi Bug (the village of Stavky), but the salt content does not exceed the permissible levels. For all years of observations, the average annual pH value did not exceed regulatory requirements. The highest water color is observed in the Udych River (32-40 °) both in winter and in summer-autumn lowlands and in spring floods, as well as high values ​​were found in the waters of the Southern Bug River - 28 ° (Khmilnyk, c. Betting). Exceedance of the maximum concentration limit BSC5 was observed at all observation points. Therefore, the waters of the Southern Bug according to this indicator can be considered quite polluted. According to this classification, moderately hard (3.0 –6.0 mmol / dm³) include the waters of the rivers: Snivoda, Desna, Sob, Pivdennyi Bug (Stavky village); to hard (6.0-9.0 mmol / dm3) the following rivers: Udych, Ustya, Rudka, Southern Bug (Vinnytsia, Ladyzhyn, Khmilnyk). The content of nitrites in the waters of the rivers of the Southern Bug basin fluctuates. In spring floods the values ​​are slightly higher than the summer-autumn lows, in winter the lows are slightly increased. The content of nitrates is not higher than the MPC, compared to other observation points, the highest values ​​were found in the Southern Bug (Ladyzhyn) - 16 - 18.6 mg / dm3. Exceedances of the maximum concentration limit for phosphorus were not observed. The content of iron (Fezag) is an excess of the MPC and these indicators were found at almost all observation points. Seasonal changes in Cu concentrations were not detected. The content of Mn slightly exceeded the MPC in the spring floods in the waters of the Udych River and the Southern Bug River. The odor of surface waters fluctuated depending on the temperature value, in particular, in the summer-autumn period the average values ​​are the highest - 3-4 points, and in winter - the lowest - 0-1 points. Turbidity at almost all observation points exceeds the MPC, surface waters are turbid.&#x0D; Keywords: river basin, anthropogenic transformation, geosystem, surface water quality, spatial model, Vinnytsia region, geoecological research.