Effects Of Different Contaminants Research Articles

Benzene Oxidation over Pt Loaded on Fly Ash Zeolite X

In the present study, zeolite X (FANaX) was synthesized from coal fly ash (FA) by a two-step high-temperature method. In order to follow the effect of different contaminants in the starting coal ash, zeolite X was also synthesized from pure chemicals according to a classical recipe (NaX). Iron was loaded on this reference zeolite with the amount which was contained in the coal FA. The final catalytic samples were obtained by wet impregnation of Pt nanoparticles on both types of zeolite crystals. The most active samples in the benzene oxidation were the platinum-modified ones and, among them, the Pt-impregnated FA zeolite (Pt FANaX). The comparison of the catalytic activity of Pt FANaX with the reference PtFe NaX zeolite showed a temperature difference of 10 °C in favor of Pt FANaX at 50% benzene conversion. From these results, it can be concluded that FA zeolites are a good, cheaper and environmentally friendly alternative to traditional zeolites, synthesized from pure chemicals, which can be applied in the preparation of catalysts for the purification of gaseous mixtures from harmful organic compounds.

Luminescence Toxicological Analysis of Water Supply Systems in Dispersed Rural Areas: A Case Study in Boyacá, Colombia

The quality of water supply systems is still a major problem in developing countries, especially in rural areas. The acute bioluminescence V. fischeri inhibition assay is widely recognized as a toxicological method that can be used to detect the acute effects of different contaminants. In this study, the physicochemical characteristics and toxicology of 72 water samples collected in 18 rural aqueducts located in Boyacá (Colombia) were evaluated. The primary economic activities identified as potential influencers of water quality in the water supply basins were agriculture (n = 3), livestock (n = 2), and domestic sewage discharge (n = 1). The average luminescence inhibition rate was 66%, with a minimum of 29%, and a maximum of 97%. A total of 85% of the tested samples (n = 61) had “moderate acute hazard”, while 15% (n = 15) had “acute hazard”. A total of 95% of the aqueducts distributed water with high risk. There was a weak positive correlation between the apparent color and the V. fischeri inhibition rate (p < 0.05). The water treatments, including disinfection, and the economic activities had no correlation with the inhibition rate of luminescent bacteria. The results of this investigation can be used by sanitary authorities to incorporate future toxicological monitoring of chemical contaminants, such as humic substances and metals, into water-quality monitoring in rural areas.

Catalyst degradation under different test and poisoning conditions – Comparison parameters definition to map the effects on proton exchange membrane fuel cell voltage

AbstractProton exchange membrane fuel cells (PEMFCs) are considered among the most promising technologies for hydrogen utilization in both stationary and transport applications. Nevertheless, the cost of its components – especially the catalyst and the membrane – is still consistent and far from the cost predicted by the US Department of Energy. It is therefore essential to predict the effect of contaminants on PEMFC materials and to estimate their useful life. The literature on this topic is consistent, but the absence of standards for the experimental tests under contaminated flows makes it difficult to extrapolate the generic degradation trends and compare the results of different publications. This work aims to collect and interpret the results of the recent studies on catalyst contamination: the voltage degradation rate and reduction effect are defined via a data modeling work to understand and compare the effects of different contaminants, their concentrations, exposure times, and current densities. Thanks to the results of the present study, some conclusions are drawn regarding the impact of the different pollutants on cell voltage decay, with attention dedicated to establishing a correlation that takes into account also the different operating conditions.

Ulva lactuca: A bioindicator for anthropogenic contamination and its environmental remediation capacity

Coastal regions are subjected to degradation due to anthropogenic pollution. Effluents loaded with variable concentrations of heavy metal, persistent organic pollutant, as well as nutrients are discharged in coastal areas leading to environmental degradation. In the past years, many scientists have studied, not only the effect of different contaminants on coastal ecosystems but also, they have searched for organisms tolerant to pollutants that can be used as bioindicators or for biomonitoring purposes. Furthermore, many researchers have demonstrated the capacity of different marine organisms to remove heavy metals and persistent organic pollutants, as well as to reduce nutrient concentration, which may lead to eutrophication. In this sense, Ulva lactuca, a green macroalgae commonly found in coastal areas, has been extensively studied for its capacity to accumulate pollutants; as a bioindicator; as well as for its remediation capacity. This paper aims to review the information published regarding the use of Ulva lactuca in environmental applications. The review was focused on those studies that analyse the role of this macroalga as a biomonitor or in bioremediation experiments.

Evaluation of the effect of organic pollutants exposure on the antioxidant activity, total phenolic and total flavonoid content of lettuce (Lactuca sativa L.) using UV–Vis spectrophotometry and chemometrics

In the present contribution, the effects of different contaminants of emerging concerns (CECs), including parabens, drugs, and polycyclic aromatic hydrocarbons (PAHs) on antioxidant activity of Lactuca sativa L. in different concentration levels (10–500 µg L−1) were evaluated using ultraviolet–visible (UV–Vis) spectrophotometry combined with chemometric techniques. The extracts of lettuce samples were investigated for the antioxidant activity (AA), total phenolic content (TPC), and total flavonoid content (TFC) after 39 days of planting and 14 days of exposure. Then, the spectroscopic data were arranged in two different data matrices, including (i) the control lettuce samples and PAHs exposed samples and (ii) control samples and parabens/drugs exposed samples. The data were then analyzed using unsupervised pattern recognition techniques of principal component analysis (PCA) and hierarchical cluster analysis (HCA) and supervised pattern recognition method of partial least squares-discriminant analysis (PLS-DA). The PCA and HCA results suggested that samples belong to different groups. Then, the PLS-DA model was applied to indicate discrimination between types of organic pollutants. The PLS-DA results showed proper discrimination between control and exposed samples with an accuracy > 90%. It is concluded that the TFC, AA, and TPC values in controls were increased under the specific exposure circumstances.

Multi-biomarker approach and IBR index to evaluate the effects of different contaminants on the ecotoxicological status of Apis mellifera

The honeybee, Apis mellifera L. (Hymenoptera: Apidae), a keystone pollinator of wild plant species and agricultural crops, is disappearing globally due to parasites and diseases, habitat loss, genetic constraints, beekeeper management issues and to the widespread use of pesticides. Besides insecticides, widely studied in this species, honeybees are also exposed to herbicides and fungicides and heavy metals whose lethal and sublethal effects need to be investigated. In this context, our study aimed to evaluate the effects of fungicides and of heavy metals on honeybees and to develop and apply a multi-biomarker approach that include an Integrated Biological Index (IBRv2) to assess the toxicological status of this species. Biomarkers of neurotoxicity (AChE and CaE), metabolic alteration (ALP, and GST) and immune system (LYS, granulocytes) were measured, following honeybees’ exposure to cadmium or to a crop fungicide, using the genotoxic compound EMS as positive control. A biomarker of genotoxicity (NA assay) was developed and applied for the first time in honeybees. At the doses tested, all the contaminants showed sublethal toxicity to the bees, highlighting in particular genotoxic effects. The data collected were analyzed by an IBRv2 index, which integrated the seven biomarkers used in this study. IBRv2 index increased with increasing cadmium or fungicide concentrations. The IBRv2 represents a simple tool for a general description of honeybees ecotoxicological health status. Results highlight the need for more in-depth investigations on the effects of fungicides on non-target organisms, such as honeybees, using sensitive methods for the determination of sublethal effects. This study contributes to the development of a multi-biomarker approach to be used for a more accurate ecotoxicological environmental monitoring of these animals.

Assessment of hydrophobicity of silicone and fiber reinforced filled epoxy composites under contamination

This paper discusses the effect of different contaminants on the contact angle of silicone and glass reinforced epoxy composites. Using a combination of fillers consisting of silica, alumina, alumina trihydrate, magnesium oxide and calcium carbonate, the surface wetting characteristics of three different epoxy composites is investigated in this work. The contact angle of the materials is studied with different contaminants individually applied and with the application of AC or DC stress. Surface energy parameters are estimated to account for the variations in the contact angle. The effect of dry heat on the contact angle is also investigated. The study shows that silicone rubber retains its hydrophobicity with different contaminants except for sea water under electrical stress. In case of the epoxy composites, the fillers help to enhance the contact angle and impart different surface wetting properties under contamination with the application of electrical stress.

Influence of contaminants on part quality during Laser-Based Powder Bed Fusion of nickel base alloys

Laser-based Powder Bed Fusion (LPBF) has become a key Additive Manufacturing (AM) technology for the production of complex metallic components within a short lead-time. Contaminated powder feedstock is a major challenge in LPBF due to the uncertain influence of contaminations on part quality. This study investigates the effects of different contaminants inside the feedstock on material density and metallurgical structure in order to evaluate their implications for serial production. Pieces of rubber gloves, human, and recoater brush hair as well as five more substances were applied manually at a defined layer during the manufacturing process of Hastelloy® X (HX) specimens. The part densities were 99.9% for all contaminated specimens. Cross-sections did not show increased porosity. For some contaminants, inclusions of foreign material residue were observed. The results for HX were evaluated and implications for comparable materials were derived. Lastly, the criticality of the investigated contaminants on part quality was analyzed.

Screening toxicological effects of different contaminants using hepatic homogenates-based ethoxyresorufin-O-deethylase in vitro

In this paper, we demonstrated the potential of an in vitro method of liver homogenate-based ethoxyresorufin-O-deethylase (EROD) to determine the toxicological effects of multiple kinds of contaminants. We evaluated the in vitro impact of nine pharmaceutically active compounds (PhACs), 13 polycyclic aromatic hydrocarbons (PAHs), and three polychlorinated biphenyls (PCBs). There were different responses of EROD to these contaminants. The response of EROD to PhACs was quite complex, exhibiting both induction and inhibition effects. PAHs and PCBs elicited a strong inhibitory response on EROD activity at high concentrations in a dose-dependent manner. PAHs showed more inhibitory effects as the number of benzene rings increased. Our in vitro bioassay seems to be a potential method for toxicological screening of multiple types of contaminants.

Genotoxic effect of dimethylarsinic acid and the influence of co-exposure to titanium nanodioxide (nTiO2) in Laeonereis culveri (Annelida, Polychaeta)

Few data are available about the effect of dimethylated forms (DMA) on aquatic organisms. As rarely a contaminant occurs alone, studies evaluating the combined effect of different contaminants in aquatic organisms are needed. In fact, the presence of nanomaterials, such as titanium dioxide nanoparticles (nTiO2), in the aquatic environment is now a reality due to its intensive production and use. So, this study evaluated the toxicological effects of DMA in an acute exposure condition and considered the potential influence of nTiO2 on the effects induced by DMA in the polychaete, Laeonereis culveri. The animals were exposed over 48 h to DMA (50 and 500 μg/l) alone or in combination with nTiO2 (1 mg/l). Biochemical parameters such as concentration of reactive oxygen species (ROS), glutathione-S-transferase (GST) activity, levels of reduced glutathione levels (GSH) and macromolecular (lipid and DNA) damage were evaluated, as well the DNA repair system. In addition, the accumulation of total As and the chemical speciation of the metalloid in the organisms was determined. The results showed that: (1) only the group exposed to 500 μg of DMA/l accumulated As and when co-exposed to nTiO2, this accumulation was not observed. (2) The levels of ROS increased in the group exposed to 50 μg/l of DMA alone and the effect was reversed when this group was co-exposed to nTiO2 (3) None of the treatments showed altered GST activity or GSH levels. (4) All groups that received nTiO2 (alone or in combination with DMA) showed lipid peroxidation. (5) The exposure to DMA (both concentrations) alone or in combination with nTiO2 induced DNA damage in L. culveri. These results showed that DMA exhibits a genotoxic effect and that co-exposure to nTiO2 had an influence on its toxicity. So the occurrence of both contaminants simultaneously can represent a threat to aquatic biota.

Pesticides diazinon and diuron increase glutathione levels and affect multixenobiotic resistance activity and biomarker responses in zebrafish (Danio rerio) embryos and larvae

BackgroundZebrafish have been increasingly used for monitoring and assessing the effects of different contaminants in the aquatic environments. In the present study, zebrafish embryos and larvae were used to study the effects of the insecticide diazinon and the herbicide diuron in regard to occurrence of oxidative stress-related cellular responses, multixenobiotic resistance (MXR)-related efflux transporter activity—which represents the first line of defense against xenobiotics in many aquatic organisms—and responses of different molecular and biochemical biomarkers.ResultsThe recently established non-invasive quantitative plate assay, which uses the fluorescent probes CM-H2DCFDA and CellTracker™ Green CMFDA and measures the fluorescence in whole zebrafish larvae, was applied to assess changes in reactive oxidative species (ROS) and glutathione (GSH) after exposure to the investigated pesticides. The results showed a significant increase of GSH after 1 h exposure of zebrafish larvae to both diazinon and diuron. Regarding the ROS induction, no significant increases in fluorescence could be detected after 2 h exposure to the investigated pesticides. Applying a newly adapted assay for MXR activity, it was determined that diuron caused no change after a 24-h exposure, but caused a significant induction of MXR activity after a 48-h exposure (indicated by a decreased amount of accumulated rhodamine B). On the other hand, diazinon caused an inhibition of MXR activity after both 24 h and 48 h exposure (indicated by an increased amount of accumulated rhodamine B). Regarding the biomarkers, different set-ups and exposure periods were applied and both molecular (gene expression) and biochemical (enzymatic activities) responses were assessed. Diazinon caused an inhibition of carboxylesterase (CES) and acetylcholinesterase (AChE) activity in zebrafish larvae, diuron inhibited AChE activity in in vitro testing, and both pesticides significantly affected gene expression and activities of some of the cytochrome P450 (CYP) family enzymes.ConclusionsThe obtained results show various effects of the investigated pesticides and will help to elucidate how aquatic animals cope with pesticides present in their environment. Additionally, the recently developed fluorescence-based assay and the newly adapted MXR activity assay proved to be useful tools for ecotoxicological risk assessment to further investigate pesticide effects.

Impacts of leachate of landfill on the groundwater hydrochemistry and size distributions and heavy metal components of colloids: a case study in NE China.

Colloids associated with heavy metals are ubiquitous in contaminated groundwater; waste accumulation at imperfectly sealed landfills can produce large amounts of leachate with colloids and heavy metal contaminants, which can pollute the downstream groundwater. In this study, three sites in a landfill were sampled to reveal heavy metal particle size distributions and their chemical compositions. The > 220nm particle sizes were the predominant size in the downstream groundwater, while the < 10nm particle sizes were the predominant size in the upstream groundwater. Total Fe increased from 35.5μg/L in the upstream groundwater to 107μg/L in the downstream groundwater. This increase was attributed to the enhanced migration and accumulation of colloids in the aqueous phase. The elements and the colloid size distribution in the landfill indirectly reflected the composition and degradation of the waste. Colloids played a key role in distribution of both solid particles and aqueous contaminants in the landfill. The results of this study will contribute to the knowledge of the effect of different contaminants in the vicinity of landfills without appropriate sealing systems.

Influence of contaminants in glycerol/water mixtures during post-treatment on physicochemical properties and separation performance of air-dried membranes

Membranes for water treatments always have a glycerol/water post-treatment before air-drying to maintain their microporous structure during and after air-drying. However, the presence of trace amounts of impurities in glycerol/water mixtures may have big effects on both pore size and pure water permeability (PWP) of the treated membranes, especially when the membranes have a pore size near or in the nanofiltration (NF) range. By investigating the effects of different contaminants to membranes, this article may provide new guidance for membrane scientists and engineers to study the science and engineering on how to properly post-treat membranes before and after the air-drying process.

Unraveling the performance of the benthic index AMBI in a subtropical bay: The effects of data transformations and exclusion of low-reliability sites

We investigated the relationship between the AMBI index and different contamination proxies in an urbanized bay in South America (SE Brazil), and the effect of (a) abundance data transformation and (b) exclusion of low-reliability sites (high SD; low N) on the index' performance. Poor ecological quality and opportunistic species were related to an increase in contaminants concentrations and mud content. Good ecological status and sensitive species (EG I) were mainly related to increased hydrodynamics. Data transformation caused minimal changes to the overall relationships, but exclusion of low-reliability sites improved the relationship between ecological groups and contamination proxies. Our results show that AMBI is robust in detecting effects of different contaminants in the area and reinforce the importance of the index as a tool for coastal management, but local joint efforts are needed to improve and adjust local species classification in ecological groups to improve the index' performance.

Polychlorinated biphenyls (PCBs) alter DNA methylation and genomic integrity of sheep fetal cells in a simplified in vitro model of pregnancy exposure

Polychlorinated biphenyls (PCBs) are persistent organic pollutants ubiquitously detectable in the environment and in the food chain. Prenatal exposure to PCBs negatively affects fetal development and produces long-term detrimental effects on child health. The present study sought to evaluate the cytotoxic and genotoxic effects of chronic PCB exposure on fetal cells during pregnancy. To this aim, sheep embryonic fibroblasts (SEF) and amniocytes (SA) were cultured in vitro in the presence of low doses of PCBs for a period of 120days, comparable to the full term of ovine pregnancy. Cellular proliferation rates, global DNA methylation, chromosome integrity, and markers of DNA damage were evaluated at different time points. Moreover, SEF treated with PCBs for 60days were left untreated for one further month and then examined in order to evaluate the reversibility of PCB-induced epigenetic defects. PCB-treated SEF were more sensitive than SA treated with PCBs, in terms of low cell proliferation, and increased DNA damage and global DNA methylation, which were still detectable after interruption of PCB treatment. These data indicate that chronic exposure of fetal cells to PCBs causes permanent genomic and epigenetic instability, which may influence both prenatal and post-natal growth up to adulthood. Our in vitro model offer a simple and controlled means of studying the effects of different contaminants on fetal cells - one that could set the stage for targeted in vivo studies.

Evaluation of the Effect of Different Contaminants on the Shear Bond Strength of a Two-step Self-etch Adhesive System, One-step, Self-etch Adhesive System and a Total-etch Adhesive System

Evaluation of the Effect of Different Contaminants on the Shear Bond Strength of a Two-step Self-etch Adhesive System, One-step, Self-etch Adhesive System and a Total-etch Adhesive System

Subchronic atrazine exposure changes defensive behaviour profile and disrupts brain acetylcholinesterase activity of zebrafish

Animal behaviour is the interaction between environment and an individual organism, which also can be influenced by its neighbours. Variations in environmental conditions, as those caused by contaminants, may lead to neurochemical impairments altering the pattern of the behavioural repertoire of the species. Atrazine (ATZ) is an herbicide widely used in agriculture that is frequently detected in surface water, affecting non-target species. The zebrafish is a valuable model organism to assess behavioural and neurochemical effects of different contaminants since it presents a robust behavioural repertoire and also all major neurotransmitter systems described for mammalian species. The goal of this study was to evaluate the effects of subchronic ATZ exposure in defensive behaviours of zebrafish (shoaling, thigmotaxis, and depth preference) using the split depth tank. Furthermore, to investigate a putative role of cholinergic signalling on ATZ-mediated effects, we tested whether this herbicide alters acetylcholinesterase (AChE) activity in brain and muscle preparations. Fish were exposed to ATZ for 14days and the following groups were tested: control (0.2% acetone) and ATZ (10 and 1000μg/L). The behaviour of four animals in the same tank was recorded for 6min and biological samples were prepared. Our results showed that 1000μg/L ATZ significantly increased the inter-fish distance, as well as the nearest and farthest neighbour distances. This group also presented an increase in the shoal area with decreased social interaction. No significant differences were detected for the number of animals in the shallow area, latency to enter the shallow and time spent in shallow and deep areas of the apparatus, but the ATZ 1000 group spent significantly more time near the walls. Although ATZ did not affect muscular AChE, it significantly reduced AChE activity in brain. Exposure to 10μg/L ATZ did not affect behaviour or AChE activity. These data suggest that ATZ impairs defensive behaviours of zebrafish, which could be related to its action on brain cholinergic neurotransmission. Moreover, the use of the split depth tank could be an alternative strategy to assess group behaviour and depth preference after exposure to chemical compounds.

Two naphthalene degrading bacteria belonging to the genera Paenibacillus and Pseudomonas isolated from a highly polluted lagoon perform different sensitivities to the organic and heavy metal contaminants

Two bacterial strains were isolated in the presence of naphthalene as the sole carbon and energy source from sediments of the Orbetello Lagoon, Italy, which is highly contaminated with both organic compounds and metals. 16S rRNA gene sequence analysis of the two isolates assigned the strains to the genera Paenibacillus and Pseudomonas. The effect of different contaminants on the growth behaviors of the two strains was investigated. Pseudomonas sp. ORNaP2 showed a higher tolerance to benzene, toluene, and ethylbenzene than Paenibacillus sp. ORNaP1. In addition, the toxicity of heavy metals potentially present as co-pollutants in the investigated site was tested. Here, strain Paenibacillus sp. ORNaP1 showed a higher tolerance towards arsenic, cadmium, and lead, whereas it was far more sensitive towards mercury than strain Pseudomonas sp. ORNaP2. These differences between the Gram-negative Pseudomonas and the Gram-positive Paenibacillus strain can be explained by different general adaptive response systems present in the two bacteria.

Hydrogen quality for fuel cell vehicles – A modeling study of the sensitivity of impurity content in hydrogen to the process variables in the SMR–PSA pathway

As fuel cell vehicles approach wide-scale deployment, the issue of the quality of hydrogen dispensed to the vehicles has become increasingly important. The various factors that must be considered include the effects of different contaminants on fuel cell performance and durability, the production and purification of hydrogen to meet fuel quality guidelines, and the associated costs of providing hydrogen of that quality to the fuel cell vehicles. In this paper, we describe the development of a model to track the formation and removal of several contaminants over the various steps of hydrogen production by steam-methane reforming (SMR) of natural gas, followed by purification by pressure-swing adsorption (PSA). We have used the model to evaluate the effects of setting varying levels of these contaminants in the product hydrogen on the production/purification efficiency, hydrogen recovery, and the cost of the hydrogen. The model can be used to track contaminants such as CO2, CO, N2, CH4, and H2S in the process. The results indicate that a suggested specification of 0.2 ppm CO would limit the maximum hydrogen recovery from the PSA under typical design and operating conditions. The steam-to-carbon ratio and the process pressure are found to have a significant impact on the process efficiency. Varying the CO specification from 0.1 to 1 ppm is not expected to affect the cost of hydrogen significantly, although the cost of gas analysis to comply with such stringent requirements may add 2–10 cents/kg to the cost of hydrogen.

Effect of different contaminants on the α-factor: Local experimental method and modeling

In this present paper, the effect of different contaminants (single and mixture) on the variation of α-factor (a ratio of processing water to clean water volumetric mass transfer coefficients, or k L a Process water/ k L a Clean water) was investigated. Tap water and aqueous solutions with surfactants, NaCl, glucose and inert microorganism were chosen as liquid phases and an elastic membrane with a single orifice as gas sparger. This study has clearly shown that the presence of these contaminants affects the bubble generation phenomenon, the interfacial area ( a) and the different mass transfer parameters, such as the volumetric mass transfer coefficient ( k L a) and the liquid-side mass transfer coefficient ( k L). The contamination of surfactants, even in small quantities, has shown the most significant effects. The determination of the α-factor in terms of interfacial area ( α a) and k L coefficient ( α k L ) was applied to understand details of the differences of the overall α-factor. The liquid surface tension and the α-factor as α a and α k L prove to be crucial for predicting the changes of α-factor in the mixture of various contaminants.