Penetration Of Contaminants Research Articles

Research of qualitative properties of soils during construction works

The development of mankind leads to an increase in the number and diversity of sources of environmental pollution. In urban conditions, environmental pollution occurs due to exhaust emissions coming from various cars, leaks of fuel and lubricants coming from various equipment, etc. Analysis of the current state of urban areas shows that the highest concentration of pollutants is present in soils. The article deals with the problem of the territories of construction sites contaminated with combustible substances coming from construction equipment. Based on the conducted studies of the process of penetration of contaminants in the soil, conclusions are drawn about the permissible time interval for the elimination of contaminants. This data can also be used to eliminate leaks in oil pipelines.

Ultraviolet-B and Heavy Metal-Induced Regulation of Secondary Metabolites in Medicinal Plants: A Review.

Despite a rich history and economic importance, the potential of medicinal plants has not been fully explored under different abiotic stress conditions. Penetration of UV-B radiation and contamination of heavy metals are two important environmental stress for plants with remarkable influence on the defense-related and pharmaceutically important secondary metabolites of medicinal plants. UV-B and heavy metal contamination may become a critical issue that either positively or negatively affects the quality and quantity of secondary metabolites. Such effects may result from changes in the expression level of genes that encode the corresponding enzymes or the inactivation and/or stimulation of specific enzymes involved in the different biosynthetic pathways of the secondary metabolites. Therefore, a comprehensive study of the impact of UV-B and heavy metals individually and in combination on the biosynthesis and accumulation of secondary metabolites in medicinal plants is discussed in the present review.

Enhancement of barrier properties regarding contaminants from recycled paperboard by coating packaging materials with starch and sodium alginate blends

Novel composite packaging materials based on „clever paper“ (CP) (a mixture of polyethylene with calcium carbonate in a mass ratio of ∼1:1) with a coating layer of biodegradable polymers – corn starch (St) and sodium alginate (Alg) with and without activated carbon – were tested to determine their barrier properties against several substances (undecane, heptadecane, dodecane, triethylcitrate, dipropylphthalate, 4-methylbenzophenone, cholestane) that simulate the migratable contaminants from recycled paperboard. Industrial samples of synthetic films (LDPE, BOPP, BOPET, EVA, PLA, PVA), as well as films based on starch/alginate (St/Alg) blends (St/Alg 90/10 and St/Alg 50/50) have been tested as well. Good barrier properties against the penetration of mineral oils (less than 5% undecane has permeated after 10 days at 40 °C) were demonstrated by the film based on St/Alg 90/10. The coating of CP by a layer consisting of St/Alg 90/10 and activated carbon (AC) yielded the composite material CP/St/Alg 90/10/AC with very low permeability (close to aluminum foil). To further showcase the effectiveness of starch/alginate coatings against penetration of contaminants, additional tests were performed with purchased recycled paper coated by films based on St/Alg 70/30.

Applying an artificial intelligence model using multidimensional spatial-temporal data to predict arsenic contamination of groundwater

Special attention has been paid in recent years to the social and environmental implications of municipal solid waste. There are potential social and environmental issues associated with storing any waste in landfill. Soil, groundwater, and surface water contamination are issues related to landfill and the migration of contaminants by leaching to adjacent areas. The current research attempts to simulate the penetration of landfill contaminants through groundwater leaching, using PART modeling approaches. Multiple social factors, taken from five years of data from 20 counties and cities in Taiwan were used as predictors of groundwater arsenic content. The results indicate that the proposed model attains a precision rate of 87%. The findings suggest that county and city demographics and the volume of waste removed are two major factors in determining the arsenic content of groundwater. The proposed predictive model can be adopted by agencies as an effective early warning tool for groundwater arsenic levels.

Complicações na técnica de regeneração óssea guiada associada à membrana de PTFE-d: relato de caso

ABSTRACT Guided bone regeneration aims to gain vertical and horizontal bone volume in atrophic ridges, using different regenerative techniques associated with biomaterials, with occasional post-surgical complications. The objective of the case report was to describe the successive approaches to minimize and eliminate the complications presented in the postoperative period of a patient submitted to the guided bone regeneration technique. In the first surgery, the dense expanded polytetrafluoroethylene membrane (d-PTFE), supported by the tent technique and autogenous platelet graft, was used to perform the guided bone regeneration technique. After three months, the membrane was exposed, with the membrane and the retaining screws removed in the seventh month, with the installation of three Internal Hexagon implants in the areas of teeth 13, 14 and 15. The exposed threads were covered with hydroxyapatites resorbable and covered with d-PTFE membrane. A four-month postoperative panoramic radiograph suggested implant osseointegration. The guided bone regeneration technique associated with the d-PTFE membrane enabled bone neoformation, enabling the installation of osseointegrated implants in an aesthetic and functional position. The exposure of the edges of the membrane allowed the penetration of fluids and contamination, suggesting the worsening of the signs of infection and purulent secretion. On the contrary, the exposure of central areas did not cause inflammatory and infectious signs.

LDPE and HDPE Microplastics Differently Affect the Transport of Tetracycline in Saturated Porous Media.

The accumulation of microplastics (MPs) in soil and sediments may influence the penetration of contaminants into subsurface environments. However, little attention has been paid to comparing the different roles of two common polyethylene (PE) types—low-density polyethylene (LDPE) and high-density polyethylene (HDPE). In this study, the transport behaviors of tetracycline in saturated quartz sand columns in the presence and absence of these two MPs were investigated, respectively. The results showed that both types of PE MPs restrained the mobility of tetracycline at neutral conditions, while such detrimental effects were weak at acid and alkaline conditions. The degree of nonequilibrium adsorption was higher, and tetracycline transferred easier to the kinetic site for the existence of LDPE than of HDPE. The increased roughness and Brunauer-Emmett-Teller (BET) surface areas, more negative zeta potentials and the formation of oxygen function groups on the surface of MPs after UV-weathering intensified the retardation of tetracycline transport. This study revealed that the PE type and weathering should be taken into account in risk assessment, along with the solution chemistry.

Adopting Who Guidance on Fabric Masks for COVID-19

On June 5, 2020, the World Health Organization (WHO) released updated guidance on the design and use of fabric masks for COVID-19. This Commentary discusses the new guidance on non-medical fabric masks as supplementary risk reduction strategies alongside physical distancing and hand hygiene, highlighting key differences from earlier Centers for Disease Control (CDC) guidelines. Notably, while the CDC recommended cotton masks with at least two layers, the WHO now recommends masks with at least three layers including a hydrophilic inner layer (e.g., cotton) to retain droplets and hydrophobic synthetic outer layers (e.g., spunbond nonwoven polypropylene, NWPP) to enhance filtration and reduce penetration of external contaminants through the mask. This key change is supplemented with additional guidance to assist mask users and makers in choosing materials with a balance of breathability and filtration performance. Cotton masks made according to the earlier CDC guidance can be adapted to comply with the WHO update by adding a single layer spunbond NWPP mask cover.

Metal decontamination by high repetition rate nanosecond fiber laser: Application to oxidized and Eu-contaminated stainless steel

The decommissioning of metallic equipment (pipes, lane surfaces, etc.) contaminated in nuclear installations can consign large amounts of waste to storage and risk workers to radioactive exposure. Here, we study metallic-surface decontamination by laser ablation, which involves ejection and subsequent trapping of surface contamination by subjecting the surface to high-energy laser pulses. We perform laser ablation on oxidized AISI 304L stainless steel samples impregnated with non-radioactive Eu using a high repetition rate nanosecond fiber laser. The oxide layers are with a mean weight percentage of 0.1 to 2% of Eu in the volume of the oxide layer. Glow discharge mass spectrometry (GDMS) is performed to assess the cleaning-treatment efficiency and study the distribution of residual contamination with a Eu-detection limit of 100 ng/g. Our results indicate satisfactory decontamination of up to 97%. We also study the limiting factors and identify the mechanism of penetration of contaminants as induced by thermal effects. Moreover, to understand the ablation mechanism and from the perspective of industrial applications, we analyze the ablated matter to obtain the particle chemical composition and size distributions.

Yttrium Aluminum Garnet Powder Feedstock for Atmospheric Plasma Spray

High demands for higher turbine efficiency bring attention to newer and more advanced insulating materials for the high temperature components in the turbine. Yttrium aluminum garnet (YAG) has shown good insulating properties in the previous published research, such as higher temperature limitation and better resistance to calcium–magnesium–alumina–silicate environmental contaminant penetration than the more conventional yttria-stabilized zirconia systems. Whereas in literature, coatings of YAG are typically prepared by solution deposition processes, in the present work YAG powder has been prepared for more conventional thermal spraying methods. The goal is to show the potential YAG powders have as a thermal barrier coating. Different approaches for obtaining a successful deposition and a good coating have been explored. Small-sized industrial-supplied powder and larger in-house-made powder have been compared, emphasizing the importance of energy used for deposition and crystallinity in the final coating. Highly crystalline material has successfully been produced with F4 atmospheric plasma spray system without post-treatment or substrate heating.

Overview Production Process And Properties Of Galvanized Roofing Sheets

In search for solution to the challenges posed by the degradation of roofing steel sheet in an aggressive environment, galvanization of steel sheet for roofing of buildings and manufacture of other Engineering structures has been a valuable remedy. Galvanization of steel in recent years has emerged as a physical barrier which minimizes the penetration of contamination of sulphide and chloride ion. Zinc coating of steel top surface is a strategy that has been found to be effective for wide range applications. Galvanized steel sheets have been widely used by various manufacturing company. Occasional switching from steel to other metal like aluminum have not been cost effective because of the present economically situation. This makes substituting galvanized steel difficult. This mini review provides insight to the production process, stages and properties of galvanized roofing steel sheet use in Nigeria and most part of Africa.

The Mini C-Arm Sock: A Novel and Simple Technique for Draping to Prevent Contamination and Penetration.

The mini C-arm is frequently used in foot and ankle surgery. However, its continuous manipulation introduces potential means of contaminating the sterile surgical field. A simple and effective draping technique of the mini C-arm is described to minimize risk of contamination and sharps penetration that can damage the C-arm. Levels of Evidence: Level V.

Spontaneous Doping at the Polymer-Polymer Interface for High-Performance Organic Transistors.

Low- k amorphous fluorinated polymers such as poly(perfluoroalkenylvinyl ether) (CYTOP) have widely been used as gate dielectrics for organic field-effect transistors (OFETs) because of their strong hydrophobicity to prevent the penetration of moisture and other contaminants and their perfect solvent orthogonality with organic semiconductors. Here, we report a new functionality of the fluorinated low- k polymer dielectrics, which is spontaneous p doping at the dielectric-semiconductor interface in OFETs. This functionality makes the ambipolar charge transport a unipolar p type. In the OFETs based on indacenodithiophene- co-benzothiadiazole and diketopyrrolopyrrole-thieno[3,2- b]thiophene, the charge transport is obviously ambipolar when paired with common polymer dielectrics such as poly(methyl methacrylate); however, it is perfectly modulated to the unipolar p type by applying the fluorinated dielectrics of CYTOP and poly(tetrafluoroethylene) (Teflon). We propose that this modulation of charge transport results from the rearrangement of C-F bonds at the interface between the fluorine-containing dielectrics and the conjugated polymer semiconductors by proper thermal annealing. These well-aligned dipole moments lead to an abrupt downshift of the Fermi level of the semiconductor toward the highest occupied molecular orbitals near the dielectric-semiconductor interface, which provides a p-doping effect on the channel transport and results in unipolar p-type characteristics in the composed OFETs. This study reveals a new functionality of the fluorinated dielectrics for future organic electronics.

Chemicals from textiles to skin: an in vitro permeation study of benzothiazole

Despite the possible impact on human health, few studies have been conducted to assess the penetration and accumulation of contaminants in the skin after a prolonged contact with textile materials. In previous studies, we have shown that benzothiazole and its derivatives, as well as other potentially hazardous chemicals, often are present as textile contaminants in clothes available on the retail market. Since benzothiazole is a common contaminant in clothes, these can be a possible route for human chemical exposure, both systemic and onto the skin. To investigate this potential exposure, Franz-type and flow-through cells were used for the permeation studies together with a Strat-M® artificial membranes. Experiments were performed using solutions of benzothiazole, as well as contaminated textile samples in the donor chamber. Benzothiazole was demonstrated to penetrate through, as well as being accumulated in the membrane mimicking the skin. After 24 h, up to 62% of benzothiazole was found in the acceptor cell, while up to 37% was found absorbed in the skin mimicking membrane. It also was shown that there was release and permeation from contaminated fabrics. The results indicate that benzothiazole can be released from textile materials, penetrate through the skin, and further enter the human body. This will possibly also apply to other chemical contaminants in textiles, and the results of this study indicate that the presence of these textile contaminants entails potential health risks. A rough risk assessment was made for clothing textiles according to Environmental Protection Agency (EPA) and European regulations for carcinogenic and non-carcinogenic compounds, using literature data for benzothiazole.

Analysis of contaminated nuclear plant steel by laser-induced breakdown spectroscopy

Laser Induced Breakdown Spectroscopy (LIBS) has the potential to allow direct, standoff measurement of contaminants on nuclear plant. Here, LIBS is evaluated as an analytical tool for measurement of Sr and Cs contamination on type 304 stainless steel surfaces. Samples were reacted in model acidic (PUREX reprocessing) and alkaline (spent fuel ponds) Sr and Cs bearing liquors, with LIBS multi-pulse ablation also explored to measure contaminant penetration. The Sr II (407.77nm) and Cs I (894.35nm) emission lines could be separated from the bulk emission spectra, though only Sr could be reliably detected at surface loadings >0.5mgcm−2. Depth profiling showed decay of the Sr signal with time, but importantly, elemental analysis indicated that material expelled from LIBS craters is redistributed and may interfere in later laser shot analyses.

Penetration of n-Hexadecane and Water into Wood under Conditions Simulating Catastrophic Floods

Abstract To simulate fuel oil spills occurring during catastrophic floods, short-term absorption of two chemicals, n-hexadecane (representative of semivolatile organic compounds in fuel oil) and water, into southern yellow pine was gravimetrically monitored as a function of time at ambient conditions. Different scenarios were run on the basis of (1) the order of contamination (n-hexadecane followed by water or vice versa) and (2) whether the wood lateral sides were covered with epoxy. The experiments were designed to evaluate fast initial sorption, allowing separate estimation of the end-grain (i.e., total longitudinal) and lateral (i.e., surface longitudinal) liquid penetration. Presaturation of wood with water did not significantly impede the subsequent penetration of n-hexadecane, whereas the presaturation of wood with n-hexadecane led to a significant decrease of the subsequent water uptake. This difference in penetration on the basis of the order of application was explained by the differences in the polarities of the two penetrating liquids and their impacts on the interactions with the wood matrix. Calculated apparent diffusivities for end-grain and lateral penetration were similar at ca. 3 × 10−7 m2/s, indicating that filling of easily accessible near-surface voids does not have a substantial impact on the overall penetration of contaminants into wood. The n-hexadecane distribution profiles based on penetration into wood blocks (obtained by means of gas chromatography) showed that water and n-hexadecane appear to use different (although overlapping) penetration paths owing to the differences in their physical properties.

LANDFILL SITTING USING MCDM AND SPATIAL INFORMATION : A CASE STUDY IN TEHRAN METROPOLITAN

Managing Municipal Solid Waste in order to control waste materials in Tehran Metropolitan with a population of over 8.5 million persons and daily production of 7500 tons of trash seems an evitable necessity. Daily production of such amount of trash and accumulation of them in the southern part of Tehran (Kahrizak) due to lack of proper and standard methods of landfilling have caused severe problems by creating a latex lake of twelve hectares. Among these problems, penetration of infection and contamination to underground waters, causing excessive problems for soil and agricultural lands can be mentioned. In such conditions caused for Tehran, lack of solution finding for the issue would bring heavy outcomes for the Tehran Metropolitan in terms of environmental and economic issues. In this paper, efforts are taken to find a new place as a landfill by applying sustainable development approach. For this, in order to use the criteria propounded in sustainable development, multi-criteria decision making methods has been applied for weighing and spatial analysis has been used to combining them for indicating the most appropriate site. In this way, the new site would be selected by observance of sustainable development would be a place with the least environmental and social damages while being economically affordable.

LANDFILL SITTING USING MCDM AND SPATIAL INFORMATION : A CASE STUDY IN TEHRAN METROPOLITAN

Managing Municipal Solid Waste in order to control waste materials in Tehran Metropolitan with a population of over 8.5 million persons and daily production of 7500 tons of trash seems an evitable necessity. Daily production of such amount of trash and accumulation of them in the southern part of Tehran (Kahrizak) due to lack of proper and standard methods of landfilling have caused severe problems by creating a latex lake of twelve hectares. Among these problems, penetration of infection and contamination to underground waters, causing excessive problems for soil and agricultural lands can be mentioned. In such conditions caused for Tehran, lack of solution finding for the issue would bring heavy outcomes for the Tehran Metropolitan in terms of environmental and economic issues. In this paper, efforts are taken to find a new place as a landfill by applying sustainable development approach. For this, in order to use the criteria propounded in sustainable development, multi-criteria decision making methods has been applied for weighing and spatial analysis has been used to combining them for indicating the most appropriate site. In this way, the new site would be selected by observance of sustainable development would be a place with the least environmental and social damages while being economically affordable.

Quality of shallow groundwater and manure effluents in a livestock farm

Abstract The aim of the study was to assess the quality of shallow groundwater on the site pens and runoff from livestock manure heaps, in three selected farms involved in animal production and vegetable crops in the area of Plateau Proszowice. The analysis mainly included water from farm wells and effluents from manure. Additionally, water from drainage ditch running nearby farms was collected, before inflow of effluent (i.e. ditch water without manure effluent) and below inflow of effluent from heap of manure (i.e. ditch water containing manure effluent). Samples of the research material were collected from April 2012 to March 2014 at monthly intervals and analysed for the content of NO3-N, NH4-N, PO4-P, K, Na and Cl. Based on the obtained results it was found that water from the farm wells near the livestock buildings and from manure storage sites, was heavily polluted by the majority of these contaminants. The highest concentration of these pollutants, except for the NO3-N, was found in manure effluent – it exceeded a few dozen to a few hundred to any standards for water quality. There was also a significant deterioration in the quality of drainage ditch water because of the penetration of contaminants into ditch water from heaps of improperly stored manure. The water of the farm wells was characterized by excessive concentrations of NO3-N which disqualified it for drinking purposes.

Development of permeability test method for porous concrete block pavement materials considering clogging

Pervious pavement has been used widely due to efficient hydrological characteristics such as reduction of runoff during floods, providing delay of rainwater into sewer systems and ground water quality improvement. However, clogging prevents it from functioning properly due to sedimentation after a short period of service, which results to poor permeability and performance of pervious pavement. In this study, the causes of clogging were investigated and a clogging simulator was developed in order to evaluate the sustainable permeability of porous concrete block pavement in advance. Furthermore, a test method for verifying the sustainability of infiltration which can predict and assess the permeability performance by years of service was proposed. In addition, the penetration of contaminants also varies depending on vehicle vibration and the rainwater that permeates together with it. It was found that the pores were easily clogged with the vibration frequency increased, but with the amount of contaminants increased to a degree clogging had less influence on vibration. When various types of porous concrete block pavers were evaluated with the proposed sustainable permeability test method, the coefficient of permeability before and after the test have shown very high correlation.

English

Underground coal gasification (UCG) generates potential groundwater pollution because it changes local hydrogeological parameters. Groundwater pollution is caused by diffusion and penetration of contaminants generated by UCG processes towards surrounding strata and possible leaching of residue by natural groundwater flow after gasification. A large number of hazardous water-borne contaminants were identified during different UCG operations conducted so far, and in some locations long-term groundwater contaminations were observed. Organic pollutants were detected after UCG process are phenols, benzene with its derivatives, polycyclic aromatic hydrocarbons (PAHs), heterocycles etc. and inorganic pollutants includes ammonia, mercury, zinc, sulphates, cyanides, heavy metals etc. Adsorption function of coal and surrounding strata makes a significant contribution to decrease the contaminants over time and distance from the burn cavity. Possible pollution control measures regarding UCG include identifying unsuitable zone, sitting a hydraulic barrier and pumping contaminated water out for surface disposal. The paper enumerates major pollutants identified in different UCG sites and its mitigation measures during gasification processes, and groundwater remediation after gasification.   Key words: Underground coal gasification, groundwater contamination, water influx.