Concentrations Of Toxic Pollutants Research Articles

Eu2CuO4 nanostructures: A simple co-precipitation pathway, characterization, and promising photocatalytic application for dye removal under visible light

Contamination of water has become an international concern, and finding efficient and sustainable methods to eliminate harmful pollutants is crucial for ensuring that clean and safe water resources are available. A promising approach in this regard is photocatalysis, which uses light energy to initiate chemical reactions that break down organic contaminants into harmless byproducts. This study presents a nanophotocatalyst based on europium copper oxide (Eu2CuO4) for the elimination of hazardous pollutants. The fabrication of Eu2CuO4 nanostructures was achieved through a simple and rapid co-precipitation process. According to diffuse reflectance spectroscopy (DRS), Eu2CuO4 has an optical bandgap of 1.56 eV, making it suitable for use in visible light. A variety of techniques were used to characterize Eu2CuO4 nanostructures, including XRD, FESEM, FTIR, VSM, HRTEM, BET, EDS, and LC-MS. In order to maximize effectiveness, several variables were considered, such as the amount of Eu2CuO4 used, the concentration of toxic pollutants, and the pH of the solution. It was found that Eu2CuO4 was quite effective in degrading various organic pollutants, particularly methyl orange (MO) of water. Using 50 mg of Eu2CuO4 in the presence of 20 ppm MO and exposing it to visible radiation for 100 min resulted in 94.9 % of MO being destroyed. A further analysis revealed that hydroxyl radicals (•OH) and holes (h+) played a dominant role in pollutant photodegradation. In light of this finding, Eu2CuO4 may serve as a valuable candidate for developing new materials that are capable of successfully removing contaminants from water.

Dissimilatory reduction of sulfate, nitrate and nitrite ions by bacteria Desulfovibrio sp. under the influence of potassium dichromate

In the process of anaerobic respiration, sulfate reducing bacteria, besides sulfates, can use other electron acceptors: nitrates, nitrites, oxidized forms of heavy metals, in particular, hexavalent chromium, which are harmful for organisms. Selection of pollutant-resistant stains of this kind of bacteria isolated from technogenically altered ecotopes, capable of reductive transformation of various nature pollutants, is an especially relevant task for the creation of new effective remediation biotechnologies. The purpose of this work was to investigate the regularities of usage of sulfate, nitrate or nitrite ions by bacteria of the Desulfovibrio genus, isolated from Yavorivske Lake, at conditions of simultaneous presence in the medium of another electron acceptor – Cr(VI), to establish a succession of electron acceptors’ reduction by investigated sulfidogenic bacteria and to evaluate the efficiency of their possible application in technologies of complex purification of the environment from metal, sulfur and nitrogen compounds. Bacteria were grown under anaerobic conditions for 10 days in Kravtsov-Sorokin medium without Mohr’s salt. To study the efficiency of sulfate, nitrate, or nitrite ions’ reduction at simultaneous presence in the medium of Cr(VI), bacteria were sown in media with Na2SO4×10H2O, NaNO3, NaNO2 or K2Cr2O7 to final SO42–, NO3–, NO2– or Cr(VI) concentration in the medium of 3.47 (concentration of SO42– in medium of standard composition) or 1.74, 3.47, 5.21, 6.94, 10.41 mM. Biomass was determined turbidimetrically, and the concentrations of sulfate, nitrate, nitrite, ammonium ions, hydrogen sulfide, Cr(VI), Cr(ІІІ) in cultural liquid were determined by spectrophotometric method. It has been established that Cr(VI) inhibits the biomass accumulation, sulfate ions’ reduction and hydrogen sulfide production by Desulfovibrio sp. after simultaneous introduction into the medium of 3.47 mM SO42– and 1.74–10.41 mM Cr(VI). In the medium with the same initial content (3.47 mM) of SO42– and Cr(VI), bacteria reduced 2.1–2.3 times more Cr(VI) than sulfate ions with Cr(III) production at concentrations up to 2.2 times higher than hydrogen sulfide. It has been shown that K2Cr2O7 inhibits the biomass accumulation, the nitrate ions reduction and the ammonium ions production by bacteria after simultaneous addition into the medium of 3.47 mM NO3– and 1.74–10.41 mM Cr(VI) or 1.74–10.41 mM NO3– and 3.47 mM Cr(VI). In the medium with the same initial content (3.47 mM) of NO3– and Cr(VI) bacteria reduced 1.1–1.3 times more nitrate ions than Cr(VI) with the production of ammonium ions at concentrations up to 1.3 times higher than that of Cr(III). It has been established that K2Cr2O7 inhibits the biomass accumulation, the nitrite ions’ reduction and the ammonium ions’ production by bacteria after simultaneous addition into the medium of 3.47 mM NO2– and 1.74–10.41 mM Cr(VI) or 1.74–10.41 mM NO2– and 3.47 mM Cr(VI). In the medium with the same initial content (3.47 mM) NO2– and Cr(VI) the reduction of Cr(VI) by bacteria practically did not differ from the reduction of nitrite ions (was only slightly lower – up to 1.1 times), almost the same concentrations of trivalent chromium and ammonium ions in the cultural liquid were detected. The processes of nitrate and nitride reduction, carried out by bacteria of Desulfovibrio genus, were revealed to be less sensitive to the negative influence of sodium dichromate, as compared with the process of sulfate ions’ reduction, which in the medium with 3.47 mM SO42– and 1.74–10.41 mM Cr(VІ) decreased by 3.2–4.6 times as compared with this process in the medium with only Na2SO4×10H2O. The investigated strains of bacteria are adapted to high concentrations of toxic pollutants (up to 10.41 mM) and therefore are promising for application in technologies of complex environment purification from hexavalent chromium, sulfur and nitrogen compounds.

تاثیر استفاده از باطله های فراوری معدن مس سونگون به جای مصالح ریزدانه در ساخت بتن بر خواص مکانیکی و نشت فلزات سنگین

The large volume of mine tailings as well as the considerable concentration of toxic pollutants, resulted from mining activities, cause irreparable damage to the surrounding environment. The leakage of toxic elements from the mine tailings to the environment is considered as a crucial issue. The reuse of mine tailings in concrete industry is considered as one of the main management techniques to reduce their probable adverse effects. In this study, the tailings of Sungun copper mine were collected to investigate their applicability in concrete construction instead of fine-grained materials. The results revealed that the concentrations of copper, arsenic, lead, chromium, cobalt, and nickel in copper mine tailings were higher than the environmental criteria but less than the amounts required for economic recovery. Thus, tailings with a grain size of less than 297 μm were used in the construction of two series of concrete samples to replace 50 and 100% of the fine-grained part of the concrete. Moreover, some experiments including concrete slip, compressive strength, resistance to chlorine penetration, and TCLP were performed to ensure the applicability of copper mine tailings in concrete construction. In samples where copper tailings replaced 50 and 100% of fine-grained materials, the 28-day compressive strength was 32 and 41 MPa, respectively. The compressive strength increased with increasing replacement rate. According to the results, the highest leachate rates of copper, chromium, lead, zinc, cobalt, cadmium, and arsenic were 21, 2.8, 3.9, 106, 75, 0.39, and 0.82 mg/L, respectively.

Quartz Crystal Microbalance Detection of Aflatoxin B1 by Self-Assembled Monolayer Technique

Background: New biosensor techniques allowing detection of low concentrated substances show a great variety nowadays. The construction of a system with modified quartz as a part of a Quartz Crystal Microbalance (QCM) techniques helps the detection and confirmation of low toxin concentrations in a sample. Objective: The study aims to allow the application of methods for preparation and modification of the gold surface of piezoelectric crystal for detection of aflatoxin B1(AFB1) in the concentration range 0.2 - 2.0 µg/L by QCM technique (quartz - crystal microbalance). Methods: The procedure for the preparation of quartz crystal sensors for experimental purposes was performed. The quartz surface was activated and covered with self-assembled monolayer to immobilize antibody (rabbit anti-aflatoxin B1) for the detection of antigen - antibody reaction. Results: The G” corresponds to viscous properties of the material, during applied deformation of the material in the presence of different concentrations, which revealed in the sensitivity of the used resonator. Conclusion: Detection of toxic pollutants may be achieved via QCM methods, ultrasound resonator and piezoelectric quartz techniques for measurement. These techniques allow detection of significantly low concentrations of toxic pollutants, in particular, AFB1, compared to analysis with direct and indirect ELISA immunoassays.

ВЛИЯНИЕ ТРАНСПОРТНЫХ СРЕДСТВ НА КАЧЕСТВО ВОЗДУХА В РОССИИ И ИТАЛИИ И МЕХАНИЗМЫ УСТОЙЧИВОГО РАЗВИТИЯ АВТОМОБИЛЬНОГО ТРАНСПОРТА

Air quality in the megacities of Russia and Italy, despite their different specificity, causes similar concerns of the relevant state authorities with respect to vehicle emissions, as well as the concentration of toxic pollutants in urban areas. The article is devoted to the analysis of the influence of vehicles on air quality in Russia and Italy and discussion of possible approaches to reducing the negative consequences of the operation of motor vehicles. The application of various methods (engine improvement, improvement of fuel quality, development of road infrastructure, improvement of traffic organization) is discussed for both countries, as well as for other regions, with emphasis on the applicability aspects, costeffectiveness ratio. Externalities caused by transport pollution are considered with an assessment of the possibilities of limiting the impact and preventing environmental damage, as well as taking into account financial and infrastructural costs.

Does radiotherapy have consequences on plasma concentration of toxic pollutants?

Does radiotherapy have consequences on plasma concentration of toxic pollutants?

Effect of Precipitation Variability on Pollutant Concentrations in Soil: Implications for Exposure and Risk Assessments

Concentrations of toxic pollutants in surface soils must be predicted in order to assess exposures and risks that may arise from emissions at incinerators and other air pollution sources. At present, concentrations are predicted using deterministic models and time-averaged values of input parameters. This steady-state equilibrium approach does not address variability in the underlying transport and fate processes. This paper explores the variability of pollutant concentrations in surface soils that arises from precipitation, an intermittent process that governs wet deposition and leaching processes. Using long-term (45 to 50 years) historical records at 6 climato-logically diverse sites, concentrations predicted using the steady-state approach are compared to those predicted using a dynamic numerical model that simulates dry and wet deposition, leaching, and pollutant accumulation in the surface layer of soil using a daily time step. The models are compared for pollutants of low, medium, and high water solubility. Both models show that predictions depend strongly on the pollutant solubility and the precipitation pattern at the location. Average concentrations differed between locations by a factor of up to 4 due to precipitation patterns; the solubility of the pollutant had a much more pronounced effect. Both models produced similar long-term trends, for example, the duration of the period needed to achieve a quasi-steady-state pollutant concentration. However, for soluble pollutants, the dynamic model produced maximum 24-hr average concentrations that exceeded long-term averages by 4 to 8 times, and long-term predictions of the dynamic model exceeded predictions of the steady-state model by 1.9 to 3.6 times (depending on the site). These differences are caused by the steady-state assumption that deposition and leaching occur continuously. While the steady-state model can be used to estimate long-term trends of moderately to highly insoluble pollutants, the dynamic model should be used to predict short-term, maximum concentrations and both short- and long-term averages of soluble pollutants. Site-specific exposure and risk assessments should consider temporal variation and the use of a dynamic model if concentrations of soluble pollutants approach risk-based target levels.

Distribution of Chlorobenzenes, Pesticides and PCB Congeners in Lake Ontario Near the Toronto Waterfront

Abstract Concentrations of 89 toxic organic pollutants (25 contaminants, including chlorobenzenes and pesticides, and 64 PCB isomers) were measured in Lake Ontario along the Toronto Waterfront area during the spring, summer and fall of 1987. Data indicate that Humber Bay, the inner harbour, and the areas near the Toronto Main Sewage Treatment Plant (STP) are the most polluted. While contaminant levels in some offshore areas are high, average levels for most contaminants are similar to whole-lake levels. Lake Ontario receives large amounts of pollutants from atmospheric sources and the Niagara River. Consequently, the impact of both local and whole-lake sources is felt in the Toronto Waterfront Area. Thus, even if all local sources of pollution were removed, the Toronto Waterfront Area would probably remain affected by other sources, primarily the Niagara River. Concentrations of toxic pollutants would remain approximately the same as far as two kilometers from shore.