Areas Of Contamination Research Articles

Concentrations of Pb, Cd and Zn in sediments of an estuarine complex affected by ancient mining activities in Southeast Brazil

An artificial canal, built in 1852, diverted 60% of the flow of the Ribeira de Iguape River (RIR) into the northern region of the Estuarine-Lagoon Complex of Iguape-Cananéia (ELCIC), Southeast Brazil. Since then the river has become the main contributor of fresh water and suspended matter into the system. Additionally, the RIR was contaminated by mining activities, especially of Pb, which disposed their wastes directly into this river from their beginning until its cease in 1996. Thus, unknown quantities of metals began to be continuously introduced into the ELCIC. This study evaluated lead, cadmium and zinc concentrations in the surficial sediment at 10 points sampled along the ELCIC, 15 years after the closure of the mining. Zinc concentrations were in accordance with legislation and similar across the ELCIC regions, ranging from 10.4 to 22.8 µg.g-1. Lead concentrations ranged from 19.3 to 67.9 µg.g-1, with higher concentrations in the northern ELCIC region, especially in areas near to the canal and the mouth of the RIR. These values were above the Level I limits established by the Brazilian Environmental Agency, suggesting the possibility of a sediment toxicity. Cadmium was only detected (up to 3.6 µg.g-1) in the northern region, exceeding Level I limits too. However, Pb and Cd values were not above the Level II limits. Results revealed areas of moderate lead and cadmium contamination in the northern ELCIC region, still indicating a strong contribution from the ancient mining activities and from other current anthropogenic activities such as agriculture or an incorrect disposal of sewage and residues. Therefore, a continuous assessment of metal concentrations in the sedimentary record is important to monitor the ELCIC environmental quality.

Control of water contamination on side window of road vehicles by A-pillar section parameter optimization

The water contamination on the side windows of moving vehicles is a crucial issue in improving the driving safety and the comfort. In this paper, an effective optimization method is proposed to reduce the water contamination on the side windows of automobiles. The accuracy and the efficiency of the numerical simulation are improved by using the lattice Boltzmann method, and the Lagrangian particle tracking method. Optimized parameters are constructed on the basis of the occurrence of the water deposition on a vehicle’s side window. The water contamination area of the side window and the aerodynamic drag are considered simultaneously in the design process; these two factors are used to form the multi- objective optimization function in the genetic algorithm (GA) method. The approximate model, the boundary-seeded domain method, and the GA method are combined in this study to enhance the optimization efficiency. After optimization, the optimal parameters for the A-pillar section are determined by setting the boundary to an area of W = 7.77 mm, L = 1.27 mm and H =11.22 mm. The side window’s soiling area in the optimized model is reduced by 66.93%, and the aerodynamic drag is increased by 0.41% only, as compared with the original model. It is shown that the optimization method can effectively solve the water contamination problem of side windows.

The Disaster as a Factor in the Development of Modern Tourism. A Study Case Based on the Chernobyl Nuclear Power Plant

The destination which attracts tourists is the Chernobyl Exclusion Zone established in the area of radioactive contamination within a radius of 10 to 30 km around the plant. The main tourist attraction of the zone is the infrastructure of the inactive nuclear power plant, notably reactor no. 4 covered with a concrete and steel sarcophagus. The abandoned city of Pripyat, called the "ghost town", is also of unique value to tourism. The "Duga" radar station (also dubbed "The Eye of Moscow"), an artefact of the Cold War, also lies within the zone accessible to tourists. These sites, with their mysterious and dark history, are a magnet for an increasing number of tourist groups. In 1995 the zone was visited by 900 tourists. Subsequent years have brought a regular annual growth in the number of visitors to 17,800 in 2013. A decline came in 2014 (8400), which was caused by the political situation in Ukraine (e.g. Euromajdan). The last five years (2015-2019) are characterised by a very large annual increase in the number of tourists, and in some years, an almost a doubling of the humbers compared to the previous year (2015 – 16,400, 2016 – 35,100, 2017 – 46,136, 2018 – 71,869, 2019 – 124,001).

Three-dimensional characterization of airflow, heat and mass transfer in a slot-ventilated enclosure

The performance of the fluid flow, heat and contaminant transfer is numerically experimented in a slot-ventilated container in which the flow -in and -out are occurred through inlet and exit ports in combination with thermosolutal sources. The inlet source of cold air is mechanically flushed in through left vertical wall to generate mixed convection flow regime combined with the buoyant force produced due to combined thermosolutal effect along right side wall and bottom surfaces. To characterize the system performance and smooth ventilation, a new configuration with the inhomogeneous distribution of thermal and solutal buoyant forces are taken into account. To obtain the physical insights of the flow phenomena, three dimensional structures of the flow field and cooling efficiency distribution are presented over a wide range of dimensionless flow parameters such as: Reynolds number, buoyancy forces and Richardson number to optimize the heat removal rate with maximum diffusion of contaminants. The distribution of average temperature and concentration are evaluated through Nusselt number and Sherwod number, where air change per hour and cooling efficiency are evaluated justifying the experimental observations. The performance evaluation criterion is defined through Bejan number and entropy generation and estimated by the most commonly used parameters to find the influence of inflow and out flow port locations. Interactions between inlet airflow and pressure drop resulting a heat loss through the sides of the component with high streamline curvature effect which can not be predicted in 2D flow pattern. The investigated results show that fluid flow greatly influence the contaminant transfer and exhibit a significant change in movement pattern with the location of inlet and outlet which is typically observed in experiments. The presented results indicate that contaminant's trajectory and effective cooling pattern might be an effective tool to analyze the indoor air quality and investigating the possible denser contaminant areas of the ventilated enclosure.

The role of diatomite in the cultivation of legume grasses in modified black soil models

In the Article, the data of vegetation model experiments conducted in field conditions are analyzed. As the baseline criterion of leached black soil contamination, the criterion of ecological and toxicological content of mobile forms of high-density metals in the soil corresponding to the bottom boundary of environmental disaster areas of soil contamination was used. The assessment of the effect of diatomite in contaminated agricultural soil in plantings of yellow sweet clover and purple medic test plants was conducted according to the quantity of metal accumulated by the crop. The use of diatomite in models of soils contaminated by high-density metals contributed to the decrease of accumulation in plants of sweet clover and medic of lead by 1.1-1.3 order of magnitude, of zinc 2.5-2.8 fold, and of cadmium 1.8-2.5 fold.

Reliability assessment of RTV and nano-RTV-coated insulators concerning contamination severity

Currently, insulator contamination is one of the most critical causes of flashover and security problems in high voltage power systems. To overcome this problem, Room Temperature Vulcanized (RTV) silicone rubber coating and recently nano-RTV composite coating are used in the contamination area as maintenance measures for porcelain insulator in power transmission lines. Nano-RTV coating is an approach to improve the properties of porcelain insulators and reliability of the power grid. This paper proposes a new model for evaluating the relationship between contamination level and critical flashover voltage in the presence of nano-RTV coating based on experimental results. Artificial contamination test was carried out in clean fog test on coated and non-coated insulators. Besides, a comparison was made between the surface hydrophobicity of these insulators through evaluating contact angles. Finally, in order to evaluate the effect of contamination intensity through insulator electrical stability on reliability, the life time expectation model was improved and modified. This modified model was employed to evaluate reliability and performance of RTV-coated, nano-RTV-coated, and non-coated porcelain insulators. Results show that using the nano-RTV- coated insulators can improve life time and failure probability density function of insulators compared to traditional coatings and non-coated ones particularly in contaminated area.

The influence of sample preparation techniques on results of extraction of heavy metals from soil

A study of the composition of mobile compounds of heavy metals (HM) in the area of aerosol contamination by a heat supply company showed an increase in the number of these compounds near the source of contamination. In the group of loosely bound compounds, the largest part is represented by specifically sorbed compounds. Sample preparation (the degree of sample grinding) had a noticeable effect on the extractability of Zn, Cu, and Pb from the soil. During the sifting of a soil sample through a 0.25 mm sieve, the extraction of mobile forms of HM increases significantly (by 7–16 %). Thus, with an increase in the specific surface of soil particles, the extracting ability of the reagents increases. It is necessary to take into account the sample preparation used in each fractionation method to evaluate the results and compare them.

Soil sampling when examining forests for radioactive contamination

Forest ecosystems are complex areas in terms of rehabilitation of radioactively contaminated areas, so conducting an up-to-date examination of these areas for radioactive contamination is relevant. The paper considers the improvement of methods of soil sampling for obtaining representative materials in the estimation of vertical migration of 137 Cs in the soil profile and the level of soil contamination with 137 Cs. The density of radioactive soil contamination was studied by reducing the number of selected samples from 30 to 3 in the layers of 10, 20, and 30 cm. The results show that when the number of soil samples decreases, the average magnitudes of soil contamination with 137 Cs are not significantly different within each analyzed layer. It was noted that at sampling in the 10-centimeter layer, the studied indicator was 1.3–1.4 times lower than in the layers of 20 and 30 cm, and there is no difference between the latter. To obtain reliable levels of radioactive contamination of the territory, it is necessary to perform 10-time repeated sampling in the forest soil layer of 30 cm. At a decrease in the number of soil samples from 10 to 3, the fluctuation of average values of the specific activity of 137 Cs in different layers of soil profile is low. To obtain representative magnitudes of 137 Cs content in each layer of the soil profile, it is necessary to make various samplings. Thus, for 4-time repeated sampling, is sufficient for all layers of forest litter, and 6-time repeated sampling is enough for the humus-eluvial horizon. It is necessary to perform 8-time repeated sampling for the eluvial and illuvial horizon, and 10-time repeated sampling for illuvial sand and parent rock. The obtained results make it possible to carry out up-to-date examination of forests for radioactive contamination based on the updated methodology and using the obtained data on 137 Cs migration in forest soils

Segmenting areas of potential contamination for adaptive robotic disinfection in built environments

Mass-gathering built environments such as hospitals, schools, and airports can become hot spots for pathogen transmission and exposure. Disinfection is critical for reducing infection risks and preventing outbreaks of infectious diseases. However, cleaning and disinfection are labor-intensive, time-consuming, and health-undermining, particularly during the pandemic of the coronavirus disease in 2019. To address the challenge, a novel framework is proposed in this study to enable robotic disinfection in built environments to reduce pathogen transmission and exposure. First, a simultaneous localization and mapping technique is exploited for robot navigation in built environments. Second, a deep-learning method is developed to segment and map areas of potential contamination in three dimensions based on the object affordance concept. Third, with short-wavelength ultraviolet light, the trajectories of robotic disinfection are generated to adapt to the geometries of areas of potential contamination to ensure complete and safe disinfection. Both simulations and physical experiments were conducted to validate the proposed methods, which demonstrated the feasibility of intelligent robotic disinfection and highlighted the applicability in mass-gathering built environments.

ХИМИЧЕСКИЕ ЭЛЕМЕНТЫ И ВЕЩЕСТВА – ИНДИКАТОРЫ ЗАГРЯЗНЕНИЯ ПРИРОДНОЙ СРЕДЫ РЕСПУБЛИКИ АЛТАЙ

Актуальность работы обусловлена необходимостью выявления и использования в научных и практических целях приоритетных индикаторов регионального и локального загрязнения химическими элементами и веществами компонентов природной среды на территории Республики Алтай. Цель: установить ассоциации химических загрязнителей природной среды, изучить особенности их поведения в природных средах и стратифицированных природных образованиях, наметить приоритетные индикаторы областей и зон наложенного химического загрязнения на территории региона. Методы: сбор, обобщение и комплексный анализ данных, содержащихся в опубликованных и фондовых материалах научных и производственных организаций по оценке эколого-геохимической обстановки на территории Республики Алтай и смежных с ней регионов, обработка систематизированных данных методами прикладной статистики. Результаты. Охарактеризованы региональные и локальные факторы негативного воздействия на природную среду Республики Алтай. Приведены экологические последствия современного и прошлого загрязнения природной среды. Установлена высокая информативность стратифицированных природных образований при изучении прошлого загрязнения. Выделены характерные для региона основные ассоциации экотоксикантов химической природы. Раскрыты особенности загрязнения компонентов природной среды при трансграничных переносах загрязняющих веществ и при воздействии локальных источников. Выявлены природные среды, представительные для изучения наложенного загрязнения, а также химические элементы и вещества – индикаторы антропогенного загрязнения. Установлены превышающие эколого-гигиенические нормативы концентрации приоритетных индикаторов в очагах загрязнения снежного и почвенного покрова. Сделан вывод о наибольшей опасности для природной среды региона ксенобиотиков, представленных техногенными радионуклидами, компонентами ракетных топлив, хлорорганическими пестицидами.

Numerical modeling of the distribution of virus carrying saliva droplets during sneeze and cough.

Violent respiratory diseases, i.e., coronavirus (COVID-19), spread through saliva in coughs and sneezes or are even exhaled in the form of microbial pathogen micro-droplets. Therefore, in this work, a comprehensive fully coupled Eulerian–Lagrangian method has been applied for infection control, thus leading to a deeper understanding of the saliva-disease-carrier droplet transmission mechanisms and also of their trajectory tracking by using the OpenFOAM package. This model determines the droplet–air interactions, the breakup process, and turbulent dispersion forces on each micro-droplet that is expelled within the respiratory tract in a correct way. By examining a broad range of initial velocities, size distributions, injection angles of saliva micro-droplets, and mouth opening areas, we predict the maximum opening area that can be driven by micro-droplets. One important contribution of this work is to present a correlation for the length and width of the overall direct maximum reach of the micro-droplets, driven by a wide range of mild coughs to intense sneezes. Our results indicate that the movement of the expelled droplets is mainly influenced by their size, angle, velocity, and environmental factors. During a virus crisis, like COVID-19, this paper can be used to determine the “social distance” between individuals to avoid contamination, by inhaling or touching their bodies, due to these saliva-disease-carrier droplets in sneezing, at various social distance positions such as face-to-face, meeting standing, and near equipment. The safe distance must be increased to around 4 m during a sneeze. By wearing a face mask and by bending the head during a sneeze as a protective action, we can reduce the contamination area to one-third and three-quarters, respectively. Furthermore, the dispersion of the film of the expelled saliva micro-droplets and the spatial relationship between the subjects, which affects the airflow inside the room, are also analyzed in detail.

IMPROVEMENT OF GEODETIC CONTROL FOR AREAS CONTAMINATED WITH RADIONUCLIDES

The article discusses the creation of a planning-high-altitude justification at the Karazhyra coal mine, located on the territory of the Semipalatinsk nuclear test site. The purpose of creating such a justification is to monitor the boundaries of the spread of land pollution by radionuclides, which is caused by the wind transfer of coal dust. The factors that contribute to the spread of pollution are given, both at the mine and along the highway, along which contaminated coal is delivered to industrial enterprises, as well as to the population of private houses. It is indicated that for the development of the planning and altitude justification and the creation of boundary plans can be used ground and satellite technologies for the production of geodetic works. The root-mean-square error of determining the boundaries of contamination with radionuclides of land plots and coal mines should not be more than 0.50 m. In this regard, it is urgent to develop a methodology for performing geodetic works and create boundary plans in the area of radionuclide contamination of land plots.

RADIATION SURVEY IN THE VICINITY OF “BALAPAN” SITE

The article provides results of the radiation survey of a 1005 km2 area in the vicinity of “Balapan” site. Earlier research into the area adjacent to “Balapan” site served as a ground for the survey thereby revealing a large-scale area of soil contamination with 241Am. 241Am activity concentration in soil reaches values of ~200 Bq/kg. The research result showed that such a large-scale contamination is shaped as fallout “plumes” presumably caused by atmospheric tests on the “Experimental Field” ground. A feature of this contamination is a low content of fission and nuclear activation products commensurable with the global fallout background, which is uncharacteristic of nuclear fallout “plumes” formed by aboveground nuclear tests.

Spectral analysis of soil samples in environmental pollution sites in Nineveh province, using remote sensing techniques

The results of the analysis and interpretation of multi-date satelliteimages for the period between (1987-2007) in the Nineveh’s province to the presence of local spectral anomalies in some areas, reflect a clear change in the pattern of spectral using reflectivity. Analyses of spectral reflectivity using Analytical Spectral Devise (ASD) field Spectro Radiometer for selected samples of soils that have been taken by field work from some sites in the province. They gave spectral anomaly in their profile patterns, compared with other unaffected sites, which have been useful in determining and locating the pollution sites and its classification. Classification of the above pollution sites has been accomplished depending on the comparison of spectral signature of these samples with the field informations. These classes are shown on Geoenvironmental thematic map prepared at scale of 1:50000. This map includes areas of radioactive contamination and environmental, indusial and other of military activity.

Ratiometric pathlength calibration of integrating sphere-based absorption cells.

Chemical sensors based on optical absorption require accurate knowledge of the optical pathlength of the sample cell. Integrating spheres offer increased pathlengths compared to single pass cells combined with tolerance to misalignment, making them attractive for use in challenging environments subject to vibration. However, the equivalent optical pathlength can be degraded by dirt and / or condensation on the inner surface of the sphere. We present a new scheme for in-situ calibration that uses a ratiometric two-beam approach. Results are presented for an integrating sphere used in the measurement of methane by tunable diode laser spectroscopy (TDLS) at 1651nm. Reduced sphere reflectivity was simulated by applying small areas of black tape on the inner surface. At methane concentrations of 1500ppm and 3125 ppm, for areas of contamination up to 2.3% of the sphere wall, the technique reduced the error from over 50% to within ±4%. At a concentration of 6250 ppm and the most severe fouling corresponding to 2.9% wall coverage, the technique reduced the error from 55-65% to within ±11%.

Solute transport modelling to manage groundwater pollution from surface water resources

This article provides an analytical solute transport model to investigate the potential of groundwater contamination by polluted surface water in a two dimensional domain. The clogging of streambed which makes the aquifer partially penetrated by the stream, is considered in the model. The impacts of pumping process, hydraulic conductivity and clogging layer on the quality of water produced from nearby drinking water wells are evaluated. It is found that results are consistent with numerical simulation conducted by MODFLOW software. Moreover, the model is applied using data of contamination occurrence in Malaysia, where high contaminants concentrations are found close to streams. Results show that the pumping activities (rate and time period) are crucial factors when evaluating the risk of groundwater contamination from surface water. Additionally, this study illustrates that the increase in either hydraulic conductivity or leakance coefficient parameters due to the clogging layer will enlarge the area of contamination. The model is able to determine the suitable pumping rate and location of the well so that the contamination plume never reaches the extraction well, which is useful in constructing riverbank filtration sites.

Adolescents' face mask usage and contact transmission in novel Coronavirus.

The global outbreak of coronavirus has become an international public health threat. Prevention is of paramount importance to contain its spread. This study observes face mask wearing behavior and contact transmission problems in Taiwan. Teachers track student status in class. In addition to measuring body temperature and regular disinfection, classrooms require ventilation wear mask, provide alcohol spray and avoid sharing the microphone. Both questionnaire surveys and experimental were utilized. A total of 160 adults residing in Taiwan participated in the survey. The dye simulated the possible virus area on the mask surface during usage. Subjects were required to complete a questionnaire and simulate the spread of contact transmission when using a computer. Eighty-one % of respondents reported consistent use of surgical masks several times a day. They reported taking their masks off in relatively safe areas. Most people reported using one mask per day and storing the masks in their pockets. As a result, masks surface become a contamination source. In the contact experiment, ten adults were requested to don and doff a surgical mask while doing a word processing task. The extended contamination areas were recorded and identified by image analysis. The results show an average contamination area of the workspace is significant 530 cm2. When the hand touches the surface of the mask, it may spread the virus to the subsequent contact area.Significance for public healthThe epidemic has caused pressure to prevent in most countries. Through the school's auxiliary measures, students attended classes during March-June 2020 in Taiwan. Maintaining social distance and wearing masks are important ways to reduce the spread. Inadvertent hand contact with the outer surface of the mask may also cause the virus to spread indirectly. Students' "mask use behavior survey" shows that a single mask has been used repeatedly for a long time. Emulation experiment demonstrated the potential of contact among office area. Masks must be used attentively to reduce the chance of indirect transmission.

Mercury concentration in hair collected from women in artisanal small-scale gold mining areas in Camarines Norte, Philippines

After the conclusion of the Minamata Convention on Mercury, the use of mercury (Hg) has been prohibited worldwide, except in some developing countries. The Republic of the Philippines is one of the 128 signatories of the Convention. There are many artisanal and small-scale gold mining (ASGM) operations in the Philippines that still use Hg to amalgamate gold. In order to know the direct effect of exposure to Hg on women’s hair, we performed the proton-induced X-ray emission analysis of Hg concentrations in the hair samples collected from women at risk of Hg contamination, in both ASGM and non-ASGM areas in Camarines Norte, Philippines. At the same time of the hair sampling, we also conducted interviews with the women about their lives. From the analysis results, we found that the range of Hg concentrations in the hair samples was at a safe level, with no significant difference between the ASGM and non-ASGM areas. An analysis of the effect of diet on Hg concentrations in the hair samples showed a tendency toward higher Hg concentrations in women who ate more fish. Our results through hair analysis did not show a direct effect of exposure to atmospheric Hg, but further survey of local people should be necessary to reduce the risk of Hg contamination in women even after the use of Hg in ASGM eventually comes to an end.

Soil and banana crops (Musa paradisiaca L.) risk by chromium (Cr) accumulation through leachate and its health risk assessment

The leachate efluen of Semarang landfill is directly flew to the upper course of Kreo river is a fact that make Kreo river is possibly contaminated by heavy metal. Many banana trees are planted around the contaminated0soil. This study was conducted to determine Cr toxicity on banana trees that grow on contaminated soil and to determine public health risks that is caused by leachate of Semarang landfill. The measurement of bioaccumulation factor as the basic data for environmental safety and as the evaluation of wastewater processing is conducted through Cr level measurement. The research shows 1) Cr concentration on WWTP Jatibarang Semarang landfill’s efluen leachate in the rainy season exceeds the environmental safety limit. 2) Cr concentration in the water before and the after of efluen leachate contamination is under the standard. 3) Cr contamination in the soil around Jatibarang landfill’s efluen leachate contamination area exceeds its limit. 4) The bioconcentration factor shows the banana trees can accumulate Cr from soil to the tree. 5) Most of Cr accumulation in the banana trees is translocated to the air and to the root of the tree. 6) The banana plants such as root, stem and pseudostem from the Cr contaminated soil is safe for consumption.

Microcomputed tomography evaluation of contamination with endodontic obturation material remnants in teeth with different root canal anatomy after post space preparation

Statement of problemWhether the amount of the endodontic obturation material remnants in a root canal prepared for a post is related to variations in the anatomic shape of the canal or whether it varies in different parts of the post space is unclear. PurposeThe purpose of this in vitro study was to estimate the extent of root canal contamination with remnants of the obturation material after post space preparation in relation to the anatomic shape of the root canals by means of microcomputed tomography. Material and methodsFifty freshly extracted teeth were divided into 5 test groups with respect to the root anatomy of different tooth types. The root canals were shaped and obturated with gutta percha. The space for the glass fiber post was prepared with standardized drills, and all specimens were scanned by microcomputed tomography. The areas of residual obturation material on the root canal walls in the coronal and apical parts of the prepared post space were estimated by using a 3D visualization software program. Parametric and nonparametric dispersive analysis (analysis of variance and Kruskal-Wallis) and Wilcoxon tests were used for statistical data evaluation (α=.05). ResultsThe estimates of the root canal surface areas contaminated with residual obturation material after post space preparation were significantly larger in premolars (P≤.01), as compared with mandibular incisors and with the palatal roots of maxillary first molars. The contamination areas in different parts of the root canal (apical and coronal) reported significant differences within and between the test groups. ConclusionsThe extent of root canal contamination with remnants of endodontic obturation material after post space preparation was related to the anatomic shape of the roots and varied in the coronal and apical parts of the prepared post space.