Priority Pollutants Research Articles

Determining priority control toxic metal for different protection targets based on source-oriented ecological and human health risk assessment around gold smelting area

Determining the priority control source and pollutant is the key for the eco-health protection and risk management around gold smelting area. To this end, a case study was conducted to explore the pollution characteristics, source apportionment, ecological risk and human health risk of toxic metals (TMs) in agricultural soils surrounding a gold smelting enterprise. Three effective receptor models, including positive matrix factorization model (PMF), ecological risk assessment (ERA), and probabilistic risk assessment (PRA) have been combined to apportion eco-human risks for different targets. More than 95.0% of samples had a Nemerow pollution index (NPI) > 2 (NPImean=4.27), indicating moderately or highly soil TMs contamination. Four pollution sources including gold smelting activity, mining source, agricultural activity and atmosphere deposition were identified as the major sources, with the contribution rate of 17.52%, 44.16%, 13.91%, and 24.41%, respectively. For ecological risk, atmosphere deposition accounting for 30.8% was the greatest contributor, which was mainly loaded on Hg of 51.35%. The probabilistic health risk assessment revealed that Carcinogenic risks and Non-carcinogenic risks of all population were unacceptable, and children suffered from a greater health risk than adults. Gold smelting activity (69.2%) and mining source (42.0%) were the largest contributors to Carcinogenic risks and Non-carcinogenic risks, respectively, corresponding to As and Cr as the target pollutants. The priority pollution sources and target pollutants were different for the eco-health protection. This work put forward a new perspective for soil risk control and management, which is very beneficial for appropriate soil remediation under limited resources and costs.

Thermodynamic and kinetic analysis of the response surface method for phenol removal from aqueous solution using graphene oxide-polyacrylonitrile nanofiber mats

Phenolic compound even at low concentrations, are considered to be priority pollutants due to their significant toxicity. Electrospinning was used to create a polyacrylonitril (PAN) nanofiber, which was then impregnated with graphene oxide (GO). After a preliminary investigation into the electrospinning parameters (e.g., using various voltages and polymer concentrations), the electrospun nanofibres were tuned, this study evaluated the effectiveness of these materials in removing phenolic compounds from wastewater through adsorption. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to analyze the synthesized nanofiber mats. The scanning electron microscopy (SEM) analysis revealed that the structure of nanofiber mats was altered by the addition of graphene oxide (GO) in different ratios. Specifically, the surface of the fibres exhibited increased roughness, and the diameter of the fibres also experienced an increase. The average diameter of the fibres was measured to be (134.9 ± 21.43 nm) for the PAN/2.5% GO composite and (198 ± 33.94 nm) for the PAN/5% GO composite. FTIR spectra of the PAN/GO nanocomposites nanofiber displayed distinct peaks associated with graphene oxide (GO). These included a wide peak at 3400 cm−1, related to the presence of hydroxyl (O–H) groups, as well as peaks on 1600 as well as 1000 cm−1, which indicated the existence of epoxy groups. In this study response surface methodology (RSM) was implemented. To enhance the efficiency of removing substances, it is necessary to optimise parameters such as pH, contact time, and dosage of the adsorbent. The optimum pH for removing phenol via all nanofiber mats was determined to be 7, while at a dose of 2 mg dose adsorbents maximum removals for pure PAN, PAN/2.5 GO, and PAN/5 GO were 61.3941, 77.2118, and 92.76139%, respectively. All the adsorbents obey Langmuir isotherm model, and the empirical adsorption findings were fitted with the second-order model kinetically, also non-linear Elovich model. The maximal monolayer adsorption capacities for PAN, PAN/2.5 GO, and PAN/5 GO were found to be 57.4, 66.18, and 69.7 mg/g, respectively. Thermodynamic studies discovered that the adsorption of phenol on all adsorbents nanofiber mats was exothermic, the adsorption of phenol on nanofiber mats decreases as the temperature increases. All the adsorbents exhibit negative enthalpy and entropy. The PAN/GO composite's superior phenol removal suggested that it could be used as a latent adsorbent for efficient phenol removal from water and wastewater streams.

Highly Efficient Photocatalytic Remediation of Carcinogenic Anthracene and Phenanthrene by green Synthesized N‐doped Prussian blue Analogues

AbstractPolycyclic aromatic hydrocarbons (PAHs) are classified as priority pollutants because of their persistent nature, carcinogenicity, and mutagenicity; therefore, they must be eliminated. Herein, synthesis of nitrogen‐doped metal hexacyanoferrate nanoparticles (N−MHCF; M=Cu, Zn) was achieved using the green protocol in co‐precipitation techniques for the oxidative removal of PAH pollutants, namely, anthracene (ANT) and phenanthrene (PHE). PXRD and XPS analysis confirmed the doping of Nitrogen in MHCF nanocomposite. The optimum conditions, concentration of PAHs (10 mg L−1), and catalyst dose (20 mg) at neutral pH under sunlight to eliminate PAHs were reported. The degradation followed the Langmuir model and Ist‐order kinetics. The highest photodegraFdation was found for N−CuHCF (ANT: 95 %; PHE: 93 %), as compared to N−ZnHCF (ANT: 90 %; PHE: 87 %), which might be due to a high negative zeta charge (−30.3 mV), surface area, and lower band gap energy (1.7 eV). The GC‐MS technique showed that photocatalysts (N−MHCF) break down PAH contaminants into minor metabolites in exposure to solar irradiation. Up to eight consecutive cycles of use were possible with nanocomposites without any appreciable decrease in activity. Largely because of favorable surface characteristics, N−MHCF nanostructure fabricated via the green method is of great importance with a bright future in industries.

Degradation of 2,4-dinitrotoluene in aqueous solution by dielectric barrier discharge plasma combined with Fe–RGO–BiVO4 nanocomposite

2,4-Dinitrotoluene (2,4-DNT) as a priority and hazardous pollutant, is widely used in industrial and military activities. In this study the synergistic effect of Fe–RGO–BiVO4 nanocomposite in a non-thermal dielectric barrier discharge plasma reactor (NTP-DBD) for degrading 2,4-DNT was evaluated. Preparation of the Fe–RGO–BiVO4 nanocomposite was done by a stepwise chemical method depositing Fe and reduced graphene oxide (RGO) on BiVO4. Field emission scanning electron microscopy (FESEM), X-ray diffraction analysis (XRD), UV–vis diffuse reflectance spectra (DRS), and energy-dispersive X-ray spectroscopy mapping (EDS-mapping) validated the satisfactory synthesis of Fe–RGO–BiVO4. To find the optimal conditions and to determine the interaction of model parameters, a central composite design (RSM-CCD) had been employed. 2,4 DNT can be completely degraded at: initial 2,4-DNT concentration of 40 mg L−1, Fe–RGO–BiVO4 dosage of 0.75 g L−1, applied voltage of 21kV, reaction time of 30 min and pH equal to 7, while the single plasma process reached a degradation efficiency of 67%. The removal efficiency of chemical oxygen demand (COD) and total organic carbon (TOC) were 90.62% and 88.02% at 30 min contact time, respectively. Results also indicated that average oxidation state (AOS) and carbon oxidation state (COS) were enhanced in the catalytic NTP-DBD process, which demonstrate the effectiveness of proposed process for facilitating biodegradability of 2,4-DNT.

Spectra metrology for interaction of heavy metals with extracellular polymeric substances (EPS) of Pseudomonas aeruginosa OMCS-1 reveals static quenching and complexation dynamics of EPS with heavy metals

The adsorption behavior and interaction mechanisms of extracellular polymeric substances (EPS) of Pseudomonas aeruginosa OMCS-1 towards chromium (Cr), lead (Pb), and cadmium (Cd) were investigated. EPS-covered (EPS-C) cells exhibited significantly higher (p < 0.0001; two-way ANOVA) removal of Cr (85.58 ± 0.39%), Pb (81.98 ± 1.02%), and Cd (73.88 ± 1%) than EPS-removed (EPS-R) cells. Interactions between EPS-heavy metals were spontaneous (ΔG<0). EPS-Cr(VI) and EPS-Pb(II) binding were exothermic (ΔH<0), while EPS-Cd(II) binding was endothermic (ΔH>0) process. EPS bonded to Pb(II) via inner-sphere complexation by displacement of surrounding water molecules, while EPS-Cr(VI) and EPS-Cd(II) binding occurred through outer-sphere complexation via electrostatic interactions. Increased zeta potential of Cr (29.75%), Pb (41.46%), and Cd (46.83%) treated EPS and unchanged crystallinity (CIXRD=0.13), inferred EPS-metal binding via both electrostatic interactions and complexation mechanism. EPS-metal interaction was predominantly promoted through hydroxyl, amide, carboxyl, and phosphate groups. Metal adsorption deviated EPS protein secondary structures. Strong static quenching mechanism between tryptophan protein-like substances in EPS and heavy metals was evidenced. EPS sequestered heavy metals via complexation with C-O, C-OH, CO/O-C-O, and NH/NH2 groups and ion exchange with –COOH group. This study unveils the fate of Cr, Pb, and Cd on EPS surface and provides insight into the interactions among EPS and metal ions for metal sequestration.

Monitoring of pollutants in air of Bishkek, Kyrgyz Republic

The air quality in the capital of the Kyrgyz Republic Bishkek was analyzed. The study established that there is a problem of pollution, especially in the autumn-winter period. It was shown that the main sources of emissions into the air are thermal power plants, heating in the private sector and urban transport. Priority pollutants have been identified – these are particles 2,5 and 10 microns (PM2,5 and PM10) in size. It was concluded that it is necessary to develop a modern system for monitoring harmful substances in the air. The methodology for conducting comprehensive studies to obtain a large amount of information on priority components and sources of pollution was discussed. Examples of the air monitoring in the urban environment of Bishkek were provided. The Kyrgyz-Russian Slavic University has been testing a technique for automatic monitoring of atmospheric air in the urban environment and on highways. The article discussed the use of software developed by the university. This software complements the capabilities of the Russian “Ecologist” program and can be used in any region of the Kyrgyz Republic.

Two-Dimensional CuMn-Layered Double Hydroxides: A Study of Interlayer Anion Variants on the Electrochemical Sensing of Trichlorophenol.

Despite their diverse application profile, aromatic organochlorides such as 2,4,6-trichlorophenol (TP) are widely renowned for creating a negative toll on the balance of the ecosystem. Strict regulatory regimes are required to limit exposure to such organic pollutants. By deployment of a straightforward detection scheme, electrochemical sensing technology offers a competitive edge over the other techniques and practices available for pollutant monitoring. Here, we present a streamlined hydrothermal approach for synthesizing copper-manganese layered double hydroxide (CuMn-LDH) rods to be employed as electrocatalysts for detecting TP in various media. With a focused intention to leverage the full potential of the prepared CuMn-LDHs, the interlamellar region is configured using a series of intercalants. Further, a thorough comparative analysis of their structures, morphologies, and electrochemical performance is accomplished using various analytical techniques. The electrocatalytic oxidation ability of the CuMn-LDH toward TP molecules is markedly altered by incorporating various anions into the gallery region. The dynamic attributes of the developed sensor, such as a wide linear response (0.02-289.2 μM), a low detection limit (0.0026 μM), and good anti-interfering ability, acclaim its superior viability for real-time detection of TP with exceptional tolerance to the presence of foreign moieties. Hence, this work manifests that the nature of intercalants is a vital aspect to consider while designing LDH-based electrochemical probes to detect priority pollutants.

Exploring the subcellular distribution of mercury in green alga Chlamydomonas reinhardtii and diatom Cyclotella meneghiniana: A comparative study

Mercury (Hg) is a priority pollutant of global concern because of its toxicity, its ability to bioaccumulate throughout the food web and reach significant concentrations in top predators. Phytoplankton bioconcentrate large amounts of Hg and play a key role in the entry of Hg into the aquatic food web. However, the subcellular distribution of Hg in freshwater phytoplankton, known to affect it toxicity and trophic transfer is understudied. The present study aimed at investigating the accumulation of inorganic Hg (iHg) and its subcellular distribution in freshwater phytoplankton species. To this end green alga Chlamydomonas reinhardtii and diatom Cyclotella meneghiniana were exposed to 10 and 100 nM of iHg for 2 h. The concentrations of Hg in the adsorbed, intracellular and subcellular (granules, debris, organelles, heat-stable peptides (HSP) and heat-denaturable proteins (HDP)) fractions were determined. The results showed that C. meneghiniana accumulated more Hg compared to C. reinhardtii at both iHg exposure concentrations (10 nM: 4.41 ± 0.74 vs. 1.10 ± 0.25 amol cell−1; 100 nM: 79.35 ± 10.78 vs. 38.31 ± 4.15 amol cell−1). The evaluation of the subcellular distribution of Hg, revealed that the majority of Hg was concentrated in the organelles fraction (59.7 % and 74.6 %) in the green algae. In the diatom, Hg was mainly found in the organelles (40.9 % and 33.3%) and in the HSP fractions (26.8 % and 40.1 %). The proportion of Hg in HDP fraction decreased in favor of the organelles fraction in C. reinhardtii when the exposure concentration increased, whereas the proportions in the debris and organelles fractions decreased in favor of HSP fraction in C. meneghiniana. This study provides pioneering information on the subcellular distribution of Hg within in freshwater phytoplankton, a knowledge that is essential to understand the toxicity and trophic transfer of Hg in contaminated aquatic environment.

Anthropogenic perturbations on heavy metals transport in sediments in a river-dominated estuary (Modaomen, China) during 2003–2021

Heavy metal pollutants in sediment greatly impact the estuarine environment and ecosystems, increasingly influenced by anthropogenic perturbations. Here, we examined the surface sediments of the Modaomen estuary in 2003, 2015, and 2021 to understand how human-induced changes influence the fate of heavy metals in the estuary's sediments. The potential ecological risk index (RI) suggests Cd should be the priority pollutant for environmental pollution control due to its high toxicity coefficient. In each sampling period, two main sources were identified through normalized heavy metals and PCA-MLR: natural and mixed anthropogenic sources (agricultural, industrial, and traffic activities), reflecting an increase in heavy metals pollution, later mitigated by successful environmental protection measures. Moreover, anthropogenic activities have not only impacted the sources discharge of heavy metals but have also influenced their spatial and temporal distribution through factors such as land reclamation, leading to sediment coarsening and reduced heavy metal content in specific areas.

Кадмий и свинец в кормах для аквакультуры (аналитический обзор)

Heavy metals are priority pollutants in feed for aquaculture safety. The study of the intake dynamics and distribution of heavy metals in the abiotic and biotic components of ecosystems proves their significant intake with the diet and higher accumulation during the period of active feeding. The purpose of this work was analysis of regulatory and legal documents in the field of feed control, information on contamination of water bodies and feed raw materials by cadmium and lead, their toxicity and accumulation in the organisms, as well as 2020-2023 monitoring results of feed raw materials of plant and animal origin and plant feeds analysis to justify the need for rationing their permissible levels not only in raw materials, but also in ready-made feed for aquaculture and to assess further prospects for increasing productivity and stable reproduction in the fisheries. The search for scientific information was carried out using the databases Scopus, WoS, Science- Direct, PubChem, PubMed and Elibrary in Russian and English. The information search criteria were limited by the analysis data of from the state veterinary information system «Vesta» of the lead and cadmium contamination detection in plant feeds, feed raw materials of plant and animal origin in the period from 2020 to the first quarter (inclusive) of 2023. For ready-made feeds used in aquaculture the permissible levels of cadmium and lead are not strictly regulated by documents today. The liver, kidneys, gill petals, gonads and muscles take the most active part in the exchange and deposition of heavy metals in fish. Accumulation of heavy metals mains to pathological changes: high levels of heavy metals in the water and feed of cage farms lead to changes in the basic physiological parameters of fish. However, there is not enough information about the contamination of artificial feeds used for fish grown in cages and pools. The development of preparations for leveling effects of cadmium and lead on fish, experimental works maximum close to the real conditions of cultivation and reproduction, and a more in-depth study of the participation of heavy metals in antibiotic resistance dissemination with the participation of aquatic animals are needed.

Assessing landscape disturbance in Donbass using phytomonitoring data

The article presents the results of a long-term experimental monitoring (1996-2023) of the condition of indicator plants has been implemented in the territory of Central Donbass. Due to the experiment, it was proved that flowering plants have both indices of non-plasticity in the structure of vegetative and generative parts. Indicator species analyzed: Centaurea diffusa Lam., Cichorium intybus L., Diplotaxis muralis (L.) DC., Echium vulgare L., Reseda lutea L., Senecio vulgaris L. and others. Registration sites with priority pollutants and complex pollution have been established. It was found that the geostrategic pattern obtained by mapping for traits on embryotic teratogenesis and morphological heterogeneity of indicator plants coincide on 93% of the projective coverage area. It was found out that for the period 1996-2013, 32% of the total investigated area of the Central Donbass was technogenically transformed, for the period 2014-2021, this indicator was 36%, and for 2022-2023, 41%.

Mercury in the landscape components of the Don River Delta

The Don River Delta acts as a protective environmental barrier to the washout of pollutants from adjacent drainage areas. The priority pollutant is mercury, which comes as an industrial, agricultural and domestic wastewater`s part. The mercury concentrations levels in soils were determined by expeditionary and laboratory studies: the indicators ranged from 0,025 to 0,082 μg/g d.m. in the sandy-psammophyte meadow (section №1), in the sandy steppe (section №2) – from 0,012 to 0,022 μg/g d.m., in the true meadow (section №3) – from 0,027 to 0,4 μg/g d.m. and on the landscape with near-water vegetation (section №4) – from 0,035 to 0,565 μg/g d.m. The mercury accumulation in soils according to concentration coefficients is noted in the series «the Near-water landscape(13,5) &gt; the True meadow landscape(5,9) &gt; the Sandy-psammophyte meadow landscape(2,5) &gt; the Sandy steppe landscape(1)». It was found that the soil moisture increased from the section №1 to the section №4 (on average from 18,06 to 35,4%), and the highest total biomass was recorded on the sandy-psammophyte landscape (46,55 t/ha) and the landscape with near-water vegetation (41,85 t/ha).

Determination of heavy metal contamination and pollution indices of atmospheric dust in Dushanbe and Ayvaj, Tajikistan

In this paper was studied the content of heavy metals in atmospheric dust of Dushanbe and Ayvaj. Dust samples were taken and analyzed to determine the content of heavy metals (HM): Zn, Pb, Cu, Cr, V, Ni, Co, As, Sr, MnO, TiO2 and Fe2O3 using X-ray fluorescence spectrometry. The pollution levels and environmental risks of HMs were assessed using the geoaccumulation index, contamination factor, pollution load index and potential ecological risk index. The results revealed severe contamination of atmospheric dust from Ayvaj and Dushanbe with particularly hazardous HMs such as As and Pb, the proportion of As is higher in the dust of Dushanbe, and the contribution of Pb is significant in the samples of Ayvaj. The concentrations of As, Pb, Zn, MnO, Sr, TiO2, V, Co in the dust of Dushanbe and As, Pb, Zn, Sr, TiO2, Cu in the dust of Ayvaj showed high variability (CV&gt; 35%), which indicates an intense influence of anthropogenic activity. The results of the pollution factor analysis show that As, Co, V in Ayvaj atmospheric dust samples and Pb, Cr, Ni, V, MnO in Dushanbe samples were assigned to the class of very high pollution (CF&gt;3). According to the results of the geoaccumulation index Ayvaj is heavily polluted with the following elements: V, Pb, Cr (3&lt; Igeo ≤4). Based on the ecological risk index method, As and Pb were found to be priority pollutants in the study areas.

Особенности разработки нормативов допустимого воздействия на малые реки Севастопольского региона

The aim of the study is the identification of uncertainties to improve information support for the standards of permissible impact (SPI) elaboration for small rivers of the Sevastopol region. Materials and methods. The initial data were the results of surface water bodies monitoring in the Sevastopol region, other materials on the Chernaya River basin, characterizing the conditions for the formation of runoff and the quality of waters of small rivers. Monitoring data has been provided by the territorial bodies of Roshydromet, Rospotrebnadzor, Rosprirodnadzor and State Unitary Enterprise of Sevastopol for Water Use (SUES "Vodokanal"). The shortcomings of information support for the elaboration of SPI are revealed. Pollutants were ranked according to their importance for the ecosystem of the Chernaya River tributaries and distribution in water bodies, the water quality standards are substantiated. The list of pollutants in descending order of importance for the ecosystem includes: phosphates, nitrites, ammonium ion, BOD5, suspended solids, iron, manganese, copper, magnesium, calcium, nickel, zinc, phenols, sulfates, surfactants, oil products. The most common pollutants (indicators of pollution) in the tributaries of the Chernaya River are BOD5, nitrites, phenols, manganese, iron and copper (excesses of standards are recorded for almost all objects). MPC for objects of fishery importance were adopted as standards for SPI elaboration. The exception was BOD5, for this indicator the hygienic standard was used. Assumptions are proposed that allow solving the problem of elaboration SPI under conditions of incomplete information. The calculations of the runoff volume for the years of 50 % and 95 % security, SPIchem for priority pollutants on the main hydrological seasons were performed. Analysis of the results showed that SPI differ significantly by hydrological seasons (up to 48 times) and by each indicator of pollution for different tributaries, which is especially pronounced (more than 10 times) for the Uzundzha and Kalenda Rivers in terms of BOD5, iron, phenols and phosphates. The results obtained confirms the need for differentiated regulation of the permissible impact on individual tributaries of the Chernaya River. When developing the SPI for the small rivers of the Sevastopol region, normative-methodological, informational, large-scale and target uncertainties were identified. The assumptions proposed in the work make it possible to solve practical problems of management in the field of use and protection of water bodies, but do not reduce the relevance of measures aimed at improving the information support for the SPI elaboration. Measures aimed at improving the information support for the SPI elaboration includes: organizing access to the monitoring data of the territorial body of Roshydromet («Crimean UGMS»), increasing the frequency of observations on tributaries of the Chernaya River, organization of systematic observations in the background sections and in the zones of influence of diffuse sources of pollution.

Mercury behaviour features in soils and bottom sediments of technogenic landscapes water bodies in the Rostov region

Mercury is one of the priority pollutants entering the Rostov region`s water bodies from numerous natural and anthropogenic sources. Analysis of heavy metal extraction in the world indicates a reduction in its use in production. Based on expedition and laboratory studies, the mercury concentrations levels in soils and bottom sediments were determined. The bottom sediments of the region belong to the low and medium range of impact, areas of high pollution are formed within residential areas and in coal-mining areas. Hg concentrations do not exceed MPC in soils.

Study of the dependence of component composition - degree of wastewater purification by adsorbents based on plant raw materials to control the content of priority pollutants in water bodies

In conditions of intensive development of industrial and agricultural production, measures aimed at protecting the hydrosphere from harmful substances are becoming increasingly important every year. Water purification using the sorption method and water treatment is one of the most common technological processes. Almost unlimited reserves of sorbents of natural origin, their low cost, and fairly high adsorption and ion-exchange properties make their use advisable. Sorbents developed on the basis of available secondary plant raw materials show high efficiency and open up the possibility of their practical use in solving environmental problems. New sorbents based on plant raw materials have been developed, their structure and morphology have been studied in order to identify the absorption capacity and effectiveness of use as oil sorbents. Studies of the kinetics and dynamics sorption of oil pollutants confirm the effectiveness of mentioned sorbents and sorption purification technology can be used for environmental monitoring of water bodies.

Two-dimensional Ni/Co bimetal pyrophosphate nanosheets for sensitive electrochemical detection of phenol

As a priority pollutant in many regions, phenol in environment may cause severe damage to human health and ecosystem. For the simultaneous detection of phenol in environment, a novel electrochemical sensor has been constructed in this work based on the 2D nickel cobalt pyrophosphate (denoted as NCppi) nanosheets modified glass carbon electrode (GCE). The nickel cobalt pyrophosphate was prepared by a facile hydrothermal method. The prepared 2D nickel cobalt pyrophosphate nanosheet was characterized by X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. The bimetal nickel cobalt pyrophosphate exhibited favorable catalytic activity in phenol detection. The excellent sensing performance of nickel cobalt pyrophosphate was attributed to its charge transfer mobility and abundant catalytic sites. The nickel cobalt bimetal pyrophosphate was applied to modify glass carbon electrode (denoted as NCppi/GCE) and the obtained sensor processed satisfactory analytic performance in practical detection of phenol. Cyclic voltammetry (CV) was employed to characterize electrochemical behavior of modified GCE and bare GCE in 100 μM phenol solution. Electrochemical impedance spectroscopy (EIS) and CV were employed to characterize the charge transfer process and redox nature of different electrodes in 4 mM Fe(CN)63-/4- containing 0.1 M KCl. Square wave voltammetry (SWV) was employed to detect phenol in 0.2 M phosphate buffer solution (pH=7.0). The fabricated electrochemical sensor with optimized Ni/Co ratio also exhibited a limit of detection (LOD) of 0.25 μM, a limit of qualification (LOQ) of 0.45 μM and a linear range of 0.5–100 μM with a sensitivity of 0.0269 μA/μM using square wave voltammetry (SWV) toward phenol. Besides, the electrochemical sensor showed desirable selectivity. In standard addition test of tap water sample from Longwangzui Water Plant and river water from Xunsi River, the sensor displayed reliable recoveries. The electrochemical sensor still maintained 87.5% current response after 3-week storage. The GCE was 50 $ and the cost of catalytic ink could be ignored. The active surface area of NCppi/GCE was 0.12 cm2.

Remarkable contamination characteristics, potential hazards and source apportionment of heavy metals in surface dust of kindergartens in a northern megacity of China

It is essential to understand the impact of heavy metals (HMs) present in the surface dust (SD) of kindergartens on children, who are highly sensitive to contaminated dust in cities in their growth stage. A study was conducted on 11 types of HMs present in the SD of 73 kindergartens in Beijing. This study aims to assess the pollution levels and sources of eleven HMs in Beijing’s kindergartens surface dust (KSD), and estimate the potential health risks in different populations and sources. The results indicate that Cd has the highest contamination in the KSD, followed by Pb, Zn, Ni, Ba, Cr, and Cu. The sources of these pollutants are identified as industrial sources (23.7%), natural sources (22.1%), traffic sources (30.4%), and construction sources (23.9%). Cancer risk is higher in children (4.02E-06) than in adults (8.93E-06). Notably, Cr is the priority pollutant in the KSD, and industrial and construction activities are the main sources of pollution that need to be controlled. The pollution in the central and surrounding areas is primarily caused by historical legacy industrial sites, transportation, urban development, and climate conditions. This work provides guidance to manage the pollution caused by HMs in the KSD of Beijing. Environmental implicationChildren within urban populations are particularly sensitive to pollutants present in SD. Prolonged exposure to contaminated SD significantly heightens the likelihood of childhood illnesses. The pollution status and potential health risks of HMs within SD from urban kindergartens are comprehensively investigated. Additionally, the contributions from four primary sources are identified and quantified. Furthermore, a pollution-source-oriented assessment is adopted to clearly distinguish the diverse impacts of different sources on health risks, and the priority pollutants and sources are determined. This work holds pivotal importance for risk management, decision-making, and environmental control concerning HMs in KSD.

Assessment of water quality of Shlinsky reservoir by hydrochemical indicators

The paper presents the main results of assessing the water quality of the Shlinsky reservoir for the period 2015-2019. Based on the analysis of hydrochemical data obtained by standard chemical methods, according to 22 indicators. Monitoring of the reservoir water quality until 2021 was carried out by the Dubna Ecoanalytic Laboratory. The Shlinsky reservoir is located on the border of the Tver and Novgorod regions, is part of the Vyshnevolotsk water system. The reservoir provides releases for the needs of energy, water transport and improvement of water supply in Moscow. As a result of the study, priority pollutants were identified, the water quality of the reservoir was assessed based on the results of calculating the water pollution index (WPI) and the specific combinatorial index of water pollution (SCIWP). It is shown that there is no significant anthropogenic impact on the ecosystem of a water body. The water quality of the reservoir is assessed as "moderately polluted" water (according to the value of the water pollution index) and slightly polluted - polluted water (according to the value of the specific combinatorial index of water pollution).

Source apportionment and source-specific risk assessment of bioavailable metals in river sediments of an anthropogenically influenced watershed in China

Integrated source analysis and risk assessment of metals facilitate the development of targeted risk management strategies. However, previous studies usually addressed total concentration rather than bioavailability, and consequently overestimated metal risk, especially natural source-related risk. In this study, a source-specific risk assessment was conducted by integrating the source analysis of bioavailable metals in surface sediments. Moreover, risk assessment was performed using two bioavailability-based indices: the total availability risk index (TARI) and a modified index of mean probable effect concentration quotients (mPEC-Q). A representative river watershed in eastern China was selected as the study area. Findings revealed that the total concentrations of Pb, Cu, Zn, Cr, and Ni in the sediments were 1.4–2.2 times higher than the local soil background values. Using a modified community bureau of reference (BCR) sequential extraction procedure, the dominant fraction for Pb, Cu, Zn, and Cr in the studied area was found to be the residual fraction, constituting 53.63–62.44% of the total concentrations. This suggested that a significant portion of the metals potentially originated from natural sources. Nevertheless, the concentration enrichment ratio (CER) indicated that anthropogenic sources contributed significantly, accounting for 67.84–87.68% of bioavailable metals. The positive matrix factorization (PMF) model further identified three different sources of bioavailable metals, with a descending concentration contribution sequence of industrial sources (37.61%), mixed traffic and natural sources (33.17%), and agricultural sources (29.22%). Both the TARI and mPEC-Q index values indicated that the bioavailable metals generally posed a moderate risk, and Ni was the priority pollutant. Industrial sources contributed the most to the total risk, although the contribution from TARI-based assessment (37.27%) was lower than that from the mPEC-Q assessment (46.43%). This study provides an example of the consideration of metal bioavailability in the context of source-specific risk assessments to develop more reasonable management strategies.