Heavy Contamination Research Articles

Variance estimations in the presence of intermittent interference and their applications to incoherent scatter radar signal processing

Abstract. We discuss robust estimations for the variance of normally distributed random variables in the presence of interference. The robust estimators are based on either ranking or the geometric mean. For the interference models used, estimators based on the geometric mean outperform the rank-based ones in both mitigating the effect of interference and reducing the statistical error when there is no interference. One reason for this is that estimators using the geometric mean do not suffer from the “heavy tail” phenomenon like the rank-based estimators do. The ratio of the standard deviation over the mean of the power random variable is sensitive to interference. It can thus be used as a criterion to combine the sample mean with a robust estimator to form a hybrid estimator. We apply the estimators to the Arecibo incoherent scatter radar signals to determine the total power and Doppler velocities in the ionospheric E-region altitudes. Although all the robust estimators selected deal with light contamination well, the hybrid estimator is most effective in all circumstances. It performs well in suppressing heavy contamination and is as efficient as the sample mean in reducing the statistical error. Accurate incoherent scatter radar measurements, especially at nighttime and at E-region altitudes, can improve studies of ionospheric dynamics and composition.

Bismuth-MXene nanocomposite: A low-cost portable solution for zinc (II) detection in water for safer environmental monitoring

The development of a portable and cost-effective sensor for detecting zinc ions (Zn (II)) in water addresses a crucial need for real-time monitoring of heavy metal environmental contamination. To this, here, a novel bismuth-MXene (Bi2S3-MXene) nanocomposite-based sensor is developed for the rapid and selective detection of Zn (II) ions with a simple procedure. The exceptionally selective nanocomposites were capable of detecting Zn (II) through the square-wave anodic stripping voltammetry (SWASV) technique in a linearity range of up to 3 µg/mL, achieving limit of detection (LOD) of 7 ng/mL and limit of quantification (LOQ) of 22 ng/mL with a correlation coefficient of R2 =0.9825. Subsequently, the content of Zn (II) in real tap water and sea water was successfully determined for sensitivity and practical applicability. The developed sensor demonstrated several advantages for detecting Zn (II) in water, including a rapid setup process, fast detection times, high sensitivity, more selectivity and portability. While this study focuses on Zn (II) detection, the developed platform suggests it could potentially be adapted for detecting other heavy metals in future research. This work broadens the potential applications of portable nanomaterial-based sensors for regular environmental monitoring.

Microalgae-mediated bioremediation: current trends and opportunities-a review.

Environmental pollution poses a critical global challenge, and traditional wastewater treatment methods often prove inadequate in addressing the complexity and scale of this issue. On the other hand, microalgae exhibit diverse metabolic capabilities that enable them to remediate a wide range of pollutants, including heavy metals, organic contaminants, and excess nutrients. By leveraging the unique metabolic pathways of microalgae, innovative strategies can be developed to effectively remediate polluted environments. Therefore, this review paper highlights the potential of microalgae-mediated bioremediation as a sustainable and cost-effective alternative to conventional methods. It also highlights the advantages of utilizing microalgae and algae-bacteria co-cultures for large-scale bioremediation applications, demonstrating impressive biomass production rates and enhanced pollutant removal efficiency. The promising potential of microalgae-mediated bioremediation is emphasized, presenting a viable and innovative alternative to traditional treatment methods in addressing the global challenge of environmental pollution. This review identifies the opportunities and challenges for microalgae-based technology and proposed suggestions for future studies to tackle challenges. The findings of this review advance our understanding of the potential of microalgae-based technology wastewater treatment.

Risk of Illness with Salmonella Spp. and Antibiotic-Resistant Salmonella sp. due to Consumption of Lettuce Irrigated with Water from La Ramada Irrigation District.

Despite heavy contamination of the Bogotá River with domestic and industrial waste, it remains vital for various purposes, including agricultural use at La Ramada Irrigation District. There are important concerns regarding pathogen concentrations in irrigation water at La Ramada, including the presence of antibiotic-resistant Salmonella spp. This study aimed to estimate the risk of Salmonella-related illness from consuming lettuce irrigated with Bogotá River water at La Ramada. We collected lettuce samples from 4 different sites, all irrigated with water from La Ramada. The methodology involved a process to detach Salmonella spp. from lettuce leaves, quantification through plate counts on SS agar, and establishment of antibiotic-resistant bacteria concentrations through growth on media supplemented with ampicillin or ciprofloxacin. The results showed concentrations of Salmonella spp. of 103.59,102.66, and 104.56 CFU/g lettuce at sites 1, 2, and 3, respectively, and ampicillin-resistant Salmonella spp. of 101.93, 101.31, and 102.07 CFU/g lettuce at sites 1, 2, and 3, respectively. No colonies were obtained from lettuce samples collected from site 4. Notably, we detected no isolates resistant to ciprofloxacin at any of the sites. Salmonella spp. concentrations varied greatly among sampling sites. Salmonella spp. concentrations were used to predict the daily probability of illness, with a probability of 0.59 (0.33 to 0.78, CI 95%) for Salmonella spp. and 0.3 (0.03 to 0.53, CI 95%) for ampicillin-resistant Salmonella spp.

Enhanced Cd(II) adsorption and antibacterial performance of hydrothermally synthesized FeS2/Chitosan composite

This study demonstrates the efficacy of FeS2/Chitosan composites as adsorbents for removing cadmium (Cd) from wastewater, showcasing a promising approach for environmental pollution treatment. The hydrothermal synthesis method successfully produced FeS2 and FeS2/Chitosan composites with desirable properties obtained from XRD, FTIR, SEM EDX, XPS, and UV–Vis DRS, including a pyrite crystal structure, 15 nm crystalline size, and a 2.77 eV bandgap energy. The optimized conditions for maximum Cd(II) removal were determined to be a pH of 6, a 12 mg/L Cd(II) solution, a 40 mg adsorbent loading, and a 40 min contact time, achieving complete removal through a pseudo-first-order process. Moreover, the biological studies indicated that the FeS2/Chitosan composite shows significant antibacterial activity against E.coli, further enhancing its utility in wastewater treatment applications. The composite’s dual functionality in heavy metal adsorption and antibacterial efficacy highlights its potential for comprehensive wastewater management solutions. Future research could explore the scalability of this approach and its application to other heavy metals and contaminants, further contributing to sustainable environmental practices.

Impacts of phosphorus amendments on legacy soil contamination from lead-based paint on a California, USA university campus

Lead (Pb) is one of the most common heavy metal urban soil contaminants with well-known toxicity to humans. This incubation study (2–159 d) compared the ability of bone meal (BM), potassium hydrogen phosphate (KP), and triple superphosphate (TSP), at phosphorus:lead (P:Pb) molar ratios of 7.5:1, 15:1, and 22.5:1, to reduce bioaccessible Pb in soil contaminated by Pb-based paint relative to control soil to which no P amendment was added. Soil pH and Mehlich 3 bioaccessible Pb and P were measured as a function of incubation time and amount and type of P amendment. XAS assessed Pb speciation after 30 and 159 d of incubation. The greatest reductions in bioaccessible Pb at 159 d were measured for TSP at the 7.5:1 and 15:1 P:Pb molar ratios. The 7.5:1 KP treatment was the only other treatment with significant reductions in bioaccessible Pb compared to the control soil. It is unclear why greater reductions of bioaccessible Pb occurred with lower P additions, but it strongly suggests that the amount of P added was not a controlling factor in reducing bioaccessible Pb. This was further supported because Pb-phosphates were not detected in any samples using XAS. The most notable difference in the effect of TSP versus other amendments was the reduction in pH. However, the relationship between increasing TSP additions, resulting in decreasing pH and decreasing Pb bioaccessibility was not consistent. The 22.5:1 P:Pb TSP treatment had the lowest pH but did not significantly reduce bioaccessible Pb compared to the control soil. The 7.5:1 and 15:1 P:Pb TSP treatments significantly reduced bioaccessible Pb relative to the control and had significantly higher pH than the 22.5:1 P:Pb treatment. Clearly, impacts of P additions and soil pH on Pb bioaccessibility require further investigation to decipher mechanisms governing Pb speciation in Pb-based paint contaminated soils.

Zinc Recovery from a Water Supply by Reverse Osmosis Operated at Low Pressures: Looking for Sustainability in Water Treatment Advanced Processes.

Achieving sustainability in life involves increasing efforts to recover resources. This research proposes the recovery of Zn from the Milluni lagoons, an important water supply for Bolivia, where high concentrations of Zn have been identified that exceed permitted limits, exposing a risk to health and ecosystems. The application of reverse osmosis (RO), operated with low pressures, is proposed as a first stage for the concentration of Zn and subsequent recovery of this metal through chemical precipitation. The aim was to maintain the separation efficiency of the RO operated at low pressures without presenting operational problems. As a result, 98.83% metal concentration was achieved with a laboratory-scale pilot system. The above means an important potential for large-scale Zn concentration, apart from orienting the RO toward sustainability by working with low pressures that reduce energy costs during its operation. This study can be used as a valuable reference for the advancement of sustainable technologies in the field of water treatment that simultaneously allow the recovery of resources to promote a circular economy. Finally, this study exposes an alternative for regions with heavy metal water contamination in Bolivia and worldwide.

Modification of Nano-Zero-Valent Iron and its Simultaneous Removal of Mixed Heavy Metal-Organic Contaminants in the Water Environment

With the rapid development of economy and society, heavy metal and organic contaminants, as a typical combination of mixed contaminants, enter into the environment through multiple pathways and pose a serious threat to human beings. Therefore, there is an urgent need to find an efficient, rapid and non-secondary pollution method to remove them from the water environment. However, it is difficult for traditional water treatment technologies to completely degrade them in a short time. With the continuous progress of nanotechnology, nano-zero-valent iron (nZVI) has become one of the very promising materials for the removal of mixed contaminants from aqueous environments due to its high reducibility, fast reaction rate and environmental friendliness. However, nZVI is prone to agglomeration and oxidation, which limits its practical application. Therefore, this paper reviews the modification methods of nZVI and the problems they face. In addition, the degradation mechanisms of modified nZVI for heavy metals and organic contaminants is also reviewed. The removal of heavy metal-organic mixed contaminants by sodium alginate (SA), cyclodextrin (CD) and chitosan (CS)-modified nZVI was also analyzed in details. Finally, challenges and future perspectives are discussed, as well as providing a more comprehensive perspective on nanomaterial modification.

Sustainable solutions for water hyacinth invasion: Characteristics, impacts, control, and utilization

Water hyacinth (Eichhornia crassipes) is an invasive aquatic plant that has become a global issue due to its significant ecological and socio-economic impacts. This paper discusses the characteristics and impacts of water hyacinth invasion, emphasizing the urgency of effective management strategies. Various methods for harvesting and controlling water hyacinth, including physical, biological, and chemical approaches, are elucidated. Additionally, the paper highlights the potential utilization of water hyacinth for pollutant absorption and sequestration of heavy metals, organic contaminants, and excess nutrients. Furthermore, the opportunities to convert water hyacinth biomass into bioenergy sources such as biogas and bioethanol have been identified. The paper also presents the technical feasibility of using water hyacinth to produce biochar, high-quality bio-fertilizer, animal feed, and several other valuable products.

Enhancement of filtration performance and antifouling properties of polyethersulfone membranes using Fe3O4@walnut shell-derived activated carbon nanocomposite for heavy metal ions removal

Effective water treatment methods are required owing to heavy metal ion contamination. The phase inversion approach was employed in this work to prepare antifouling polyethersulfone (PES)/Fe3O4@activated walnut shell carbon (AWSC) nanofiltration membranes to reject heavy metal ions. Characterization techniques for Fe3O4@AWSC nanoparticle (NP) included FT-IR, DLS-ZP, XRD, SEM, EDS mapping, BET, and VSM analyses. Also, SEM, EDS mapping, XRD, AFM, Zeta potential, and water contact angle investigations were utilized to characterize the synthesized membranes. The modified membranes' hydrophilicity and porosity were observed to have improved. To affirm the presence of mesoporous Fe3O4@AWSC in the membrane matrix, EDS mapping, SEM, and AFM studies were used. It was also confirmed how the membrane's characteristics and performance were influenced by the existence of mesoporous Fe3O4@AWSC. The mixed matrix membrane made of a 0.5 wt% mesoporous Fe3O4@AWSC demonstrated a high pure water flow of 72.19 L/m2 h, a flux recovery ratio of 71.66%, and a desired rejection of over 98% against Cu2+, Pb2+, and Zn2+. The 0.5 wt% NP membrane had a noticeably improved surface hydrophilicity, which promoted successful antifouling performance. The results demonstrate that a mixed-matrix antifouling Fe3O4@AWSC membrane is highly effective in eliminating heavy metal ions.

Sustainable electro-Fenton simultaneous reduction of Cr (VI) and degradation of organic pollutants via dual-site porous carbon cathode driving uncoordinated molybdenum sites conversion

Simultaneous removal of heavy metals and organic contaminants remains a substantial challenge in the electro-Fenton (EF) system. Herein, we propose a facile and sustainable “iron-free” EF system capable of simultaneously removing hexavalent chromium (Cr (VI)) and para-chlorophenol (4-CP). The system comprises a nitrogen-doped and carbon-deficient porous carbon (dual-site NPC-D) cathode coupled with a MoS2 nanoarray promoter (MoS2 NA). The NPC-D/MoS2 NA system exhibits exceptional synergistic electrocatalytic activity, with removal rates for Cr (VI) and 4-CP that are 20.3 and 4.4 times faster, respectively, compared to the NPC-D system. Mechanistic studies show that the dual-site structure of NPC-D cathode favors the two-electron oxygen reduction pathway with a selectivity of 81 %. Furthermore, an electric field-driven uncoordinated Mo valence state conversion of MoS2 NA enchances the generation of dynamic singlet oxygen and hydroxyl radicals. Notably, this system shows outstanding recyclability, resilience in real wastewater, and sustainability during a 3 L scale-up operation, while effectively mitigating toxicity. Overall, this study presents an effective approach for treating multiple-component wastewater and highlights the importance of structure-activity correlation in synergistic electrocatalysis.

PREVALENCE AND SUSCEPTIBILITY OF BACTERIA FROM USED TOOTHBRUSHES OF STUDENTS RESIDING IN HALL I AND II UNIVERSITY OF BENIN

Used toothbrushes are reservoirs for varieties of bacteria that are implicated in human disease transmission. Personal oral hygiene and removal of plaque are important roles played by the use of toothbrushes in an act endorsed for oral hygiene resolution and ubiquitously practiced in developing and developed Nations. The study aims to evaluate the prevalence and susceptibility of bacteria present in used toothbrushes of students residing in Halls I and II, University of Benin. New toothbrushes ninety (90) were bought and forty-five (45) each were distributed to students in each hall of residence, these toothbrushes were used for one month and collected for bacteria analysis. Standard bacteriological procedures were observed for the analysis. Data were analyzed using the SPSS 22.0 computer software package. Independent t-test was used to find the differences between the two variables. The value of p< 0.05 was taken to be statistically significant. Heavy bacteria contamination was associated with used toothbrushes while no bacteria contamination in the unused ones, which serves as a control. Klebsiella species 16 (35.53 %), and 19 (42.2 %) were more prevalent than coagulase-negative staphylococci species 2 (4.4 %) and 2(4.4 %) respectively from both halls. All the toothbrushes analyzed in this study had bacteria contaminates that are known to harm human health, contributing significantly to the spread of diseases, and increasing infection risks. Establishing a high aseptic protocol, storage, and management be encouraged in tertiary institution halls of residence as the incidence of these oral bacteria and individual health risks will be minimized.

Heavy Metal Pollution Status in The Main Surface Waters of The N'djili River Basin in Kinshasa, Democratic Republic of Congo: A Review with Application and Evaluation of Pollution Indices Evaluation

The aim of this study was to assess heavy metal pollution in the surface waters of the N'djili river watershed, as well as to determine the main sources of this pollution and their impact on water quality. Five sampling sites were selected in the watershed, representing a variety of urban and industrial influences. In these samples, trace metals such as lead (Pb), cadmium (Cd) and arsenic (As) were measured by atomic absorption spectrometry. The respective mean concentrations of lead (Pb), cadmium (Cd) and arsenic (As) in the surface waters of the N'djili basin are 0.066 mg/L, 0.006 mg/L and 0.310 mg/L. The mean value of the degree of contamination (Dc) in the surface waters of the N'djili basin is greater than 3, indicating heavy contamination of these waters (Lukaya river, Matete river, N'djili river, Ntshuenge river, Ngwele river). The average values of for the trace metal pollution index (HPI) are below the threshold value of 100, so overall, these waters are not very polluted. Nevertheless, particularly high concentrations were observed in the waters of the Matete River, with values exceeding 100, indicating severe localized pollution. Correlation analysis between trace metals and HPI indicates that lead and cadmium are the main contributors to surface water toxicity in the N'djili basin. These results highlight the urgent need to develop targeted strategies to reduce pollution in order to preserve public health and aquatic ecosystems.

Research on Removing Image Noise and Distortion in Machine Dial Recognition

This study aims to address the issues of image noise and distortion in machine dial recognition via initial denoising. A wavelet local threshold denoising method that combines high-frequency wavelet coefficients with wavelet decomposition coefficients in various directions is proposed. This method shows good results on 102 images of car dashboards, aircraft instrument panels, spacecraft displays, and dial instruments on robots. Although a few denoised images exhibit distortion due to intense lighting or heavy contamination, the denoising accuracy for the remaining images is 98.04%, demonstrating substantial practical value. Future research will concentrate on addressing complex image noise and structures.

Evaluation of Heavy Metals Pollution in the Sediments of Diyala River Lower Reaches, Eastern Iraq

Investigating the heavy metals in soil is important to the life of humans and living organisms. Diyala River Lower Reaches was chosen due to the changes in environmental characteristics that took place in recent years. Twelve sediment samples were collected from four different sites. The physical, and chemical properties and the concentrations of nine heavy metals were indicated. The results showed that the average concentrations of arsenic, copper, chromium, cobalt, iron, manganese, nickel, lead, and zinc are 8.5, 45.7, 538.5, 12.2, 5.07, 991.7, 183.5, 16.07, 136.5 ppm, respectively. They reflect contamination with arsenic, chromium, and nickel, while they are free of lead, and zinc contamination, according to the Environmental Protection Agency's (EPA) sediment quality guidelines. The measured contamination indices (the enrichment factor (EF), contamination factor (CF), degree of pollution (Cdeg), geographical accumulation index (Igeo), and pollution load index (PLI)), reflected high contamination factor for arsenic and chromium, and medium for manganese, nickel, lead, and zinc, while low for copper and cobalt. Based on all the results in all sampling sites indicate the presence of heavy element contamination in the sediments of the Diyala River Lower Reaches.

Effective remediation and phytotoxicity assessment of oxytetracycline and Cd co-contaminated soil using biochar

Heavy metal-antibiotic complex contamination in soil has raised much attention. Biochar is a common soil conditioner and pollutant barrier agent. However, there has rare research about biochar control effectiveness on heavy metals and antibiotics in plant-soil system. This work evaluated the impact of applying unmodified biochar (M) and H3PO4-modified biochar (PM) on Cd, OTC, and antibiotic resistance genes (ARGs) distribution in pakchoi (Brassica chinensis L.) and soil by pot experiment. Biochar can improve quality, antioxidative defense responses of plant and enzymes activity, physiochemical properties, microbial community of soil. The content of OTC, Cd, and ARGs in pakchoi were significantly reduced after applying biochar. There was a 73.08–78.48 % decrease rate in relative abundance of ARGs, a 58.96 %–59.66 % decrease rate in OTC content, and a 71.65 %–79.64 % decrease rate in available Cd content when biochar had been added to soil with OTC and Cd contaminations. The addition of 1.5 % biochar converted exchangeable Cd to residual fraction. Furthermore, applying PM biochar led to a greater reduction in Cd mobility and OTC in soil and their accumulation in pakchoi compared to M biochar. The biochar also mitigated the OTC and Cd phytotoxicity and improved plant quality and soil enzymes activity. Biochar could reduce Proteobacteria, Actinobacteria, Planctomycetes, Gemmatimonadetes, and Firmicutes abundancies. Soil organic matter accounted for the greatest proportion of variation in ARGs. Overall, the use of biochar, particularly PM biochar, was a promising approach for remediating soil contaminated with multiple pollutants.

Leakage Current Harmonic Index as A Diagnostic Technique for Tool to Assess the Surface Condition Assessment of Aged Insulator Surface Under Varying Humidity

Leakage current has been widely utilized as an effective means to monitor the pollution severity of outdoor insulators. The indices of the odd harmonic components of the leakage current have proven to be reliable indicators of insulator performance, particularly in the third to fifth harmonic orders. However, significant challenges exist in using these indices to monitor and classify the leakage current of aged insulators under varying harmonic and pollution conditions. This paper introduces the harmonic index K((3/(5+7) ) which employs third up to seventh odd harmonic component of the leakage current as a diagnostic tool to determine the pollution severity of aged insulators under light, medium and heavy contamination levels. The experiments were conducted using 12 different sets of 11kV insulators with varying degrees of aging. The results indicate that the harmonic index Ki for new and moderately aged insulators decreases with an increase in contamination and is lower than that of heavily aged insulators.

Carbon metal nanoparticle composites for the removal of pollutants

Abstract Pollution in the water bodies has been on the rise for several decades. To address this issue, many technologies involving physical, chemical, biological, and electrochemical processes are being utilised. Nevertheless, their commercial use is limited by a number of inherent drawbacks. Here, nanotechnology combined with material science has offered practical and economical ways to remove organic pollutants from the wastewater. This review will provide a detailed overview of the efficiency and applicability of various carbon-metal nanoparticle adsorbents such as heavy metals (mercury, lead, and cadmium), organic contaminants (benzene, insecticides, and polycyclic aromatic hydrocarbon), and nitrogen and sulfur compounds from the wastewater by the adsorption process. The future research direction and the encouraging future of carbon composites loaded with metal nanoparticles for environmental applications are also discussed.

A Role of Biosynthesized Zinc Oxide Nanoparticles (ZnO NPs) for Enhancing Seed Quality: A Review

Abiotic and biotic stresses impact seed growth, resulting in economic losses. Seeds are being subjected to an increasing number of biotic and abiotic stress combinations as a result of global warming and climate change, which has adverse effects on their growth and production. Drought, flood, salinity, heavy mineral contamination, cold, and heat were all found to have a negative impact on seed germination. Because of their massive surface area-to-volume ratio, nanoparticles—microscopic pieces with a nanoscale dimension ranging from 1-100 nm—have exceptional thermal conductivity, catalytic reactivity, nonlinear optical performance, and chemical durability. There are various methods for creating nanoparticles, such as chemical, physical, and biological ones. However, because dangerous chemical compounds are used as reducing agents, the chemical and physical procedures are expensive, complicated, and might be hazardous to the environment. The synthesis of nanoparticles using green approaches may be easily scaled up, and they are also cost-effective. Because of their superior qualities, greenly coordinated nanoparticles are currently preferred over traditionally delivered NPs. Green synthesis approaches are particularly appealing due to their ability to reduce nanoparticle toxicity. The use of vitamins, amino acids, and plant extracts has increased as a result. While dangerous and extremely hazardous substances are used in the chemical and physical processes that may cause environmental issues, capping and reducing agents are essential to the synthesis of nanoparticles. The capping or reducing agent used in physical and chemical processes is expensive. When used as a seed treatment, nanoparticles can enhance germination as well as the length, vigor, viability, and quality of the seedlings. This paper aims to provide an overview and evaluation of zinc oxide nanoparticles (ZnO NPs) as a potential substitute for biosynthesised nanoparticles in seed quality improvement.

Prediction of heavy metal lead contamination accident in Three Gorges Reservoir Area.

Water contamination incidents have become a significant ecological and environmental threat, particularly concerning the security of drinking water source areas (DWSAs). This research aimed to address this issue by integrating Geographic Information System (GIS) into bidimensional hydrodynamic water quality mathematical model developed using C + + and FORTRAN programming languages. The focus was on the Heshangshan drinking water source area (HDWSA), and the TECPLOT360 software was utilized for visualizing pollutant migration and dispersion processes. The study specifically considered a hypothetical lead (Pb) contamination accident, which is situated in the Three Gorges Reservoir Area (TGRA). The spatio-temporal variations in Pb concentration throughout the entire DWSA were analyzed, along with a comparison of Pb concentration changes during different water seasons. The results indicate that, during the accident, the Pb concentration at the water intake in the drought season, decline season, flood season, and impounding season reached the standard limits at 76, 58, 44, and 48 min, respectively. Moreover, the entire DWSA achieved standard levels of Pb concentration at 124, 89, 71, and 74 min during the respective seasons. The study also observed an expansion and subsequent contraction of the Pb contamination area in the DWSA, with the transfer rate of Pb concentration ranked as flood season > impounding season > decline season > drought season.