Artykuły w czasopismach na temat „And contaminants”
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Olson, Nathan D., Justin M. Zook, Jayne B. Morrow i Nancy J. Lin. "Challenging a bioinformatic tool’s ability to detect microbial contaminants usingin silicowhole genome sequencing data". PeerJ 5 (12.09.2017): e3729. http://dx.doi.org/10.7717/peerj.3729.
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High sensitivity methods such as next generation sequencing and polymerase chain reaction (PCR) are adversely impacted by organismal and DNA contaminants. Current methods for detecting contaminants in microbial materials (genomic DNA and cultures) are not sensitive enough and require either a known or culturable contaminant. Whole genome sequencing (WGS) is a promising approach for detecting contaminants due to its sensitivity and lack of need fora prioriassumptions about the contaminant. Prior to applying WGS, we must first understand its limitations for detecting contaminants and potential for false positives. Herein we demonstrate and characterize a WGS-based approach to detect organismal contaminants using an existing metagenomic taxonomic classification algorithm. Simulated WGS datasets from ten genera as individuals and binary mixtures of eight organisms at varying ratios were analyzed to evaluate the role of contaminant concentration and taxonomy on detection. For the individual genomes the false positive contaminants reported depended on the genus, withStaphylococcus,Escherichia, andShigellahaving the highest proportion of false positives. For nearly all binary mixtures the contaminant was detected in thein-silicodatasets at the equivalent of 1 in 1,000 cells, thoughF. tularensiswas not detected in any of the simulated contaminant mixtures andY. pestiswas only detected at the equivalent of one in 10 cells. Once a WGS method for detecting contaminants is characterized, it can be applied to evaluate microbial material purity, in efforts to ensure that contaminants are characterized in microbial materials used to validate pathogen detection assays, generate genome assemblies for database submission, and benchmark sequencing methods.
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Rouel, Melissa, Richard J. Stevenson i Evelyn Smith. "Examination of Responses Involved in Contamination Aversion Based on Threat Type". Journal of Social and Clinical Psychology 37, nr 2 (luty 2018): 83–106. http://dx.doi.org/10.1521/jscp.2018.37.2.83.
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There is evidence that different types of contaminants produce different responses and have different motivations for avoidance. Contaminants directly associated with disease (direct contaminants) are motivated by disgust avoidance, whereas contaminants indirectly associated with disease (indirect contaminants) and contaminants associated with harmful substances (harm contaminants) are motivated by harm avoidance and threat estimations. This study aims to confirm this distinction between contaminant types and examine the role of cognitive load, awareness and time on processing these threats. One hundred and four participants completed three chain of contagion tasks with direct, indirect, and harm contaminants. Cognitive load, awareness of contamination and time were manipulated during the tasks. Consistent with previous findings, direct contaminants produced stronger disgust responses, while harm and indirect contaminants produced stronger threat estimations. Increasing cognitive load did not impact processing of any type of contaminant. There was evidence that a time delay reduced the spread of contagion for all contaminants. This highlights the importance of time in altering the perception of contamination threat. Implications and future research directions are discussed.
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Gewurtz, Sarah B., i Miriam L. Diamond. "Distribution and burdens of bioaccumulative contaminants in the Lake Erie food web: A review". Environmental Reviews 11, nr 3 (1.09.2003): 141–60. http://dx.doi.org/10.1139/a03-014.
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The bioaccumulation of organic contaminants in the Lake Erie food web is reviewed in context of the numerous changes experienced by the system. In the late 1960s, internal lake processes, related to the eutrophic status of the lake, minimized contaminant bioaccumulation despite high contaminant loadings. From the 1970s to 1980s contaminant concentrations decreased at different rates in many species of different trophic levels, coincident with decreased loadings to the lake. Since the early 1980s contaminant concentrations in biota have not changed consistently. Several factors have been proposed to account for these patterns, including reduced nutrient loadings and productivity, and the invasion of several exotic species such as zebra mussels. These factors have altered the food web structure and the internal distribution of contaminants in the lake. Emerging and continuing issues, such as climate change, invasions of additional exotic species, new chemical contaminants of concern, and algal toxins will likely impact contaminant dynamics in the future.Key words: Lake Erie, bioaccumulative contaminants, food web.
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Montagna, Paul A., Stephen C. Jarvis i Mahlon C. Kennicutt, II. "Distinguishing between contaminant and reef effects on meiofauna near offshore hydrocarbon platforms in the Gulf of Mexico". Canadian Journal of Fisheries and Aquatic Sciences 59, nr 10 (1.10.2002): 1584–92. http://dx.doi.org/10.1139/f02-131.
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Offshore hydrocarbon production effects are localized in the Gulf of Mexico extending only 200 m from platforms. Effects are caused by the contaminant gradient or the fouling community on platform legs. To distinguish between contaminant and reef effects, meiofauna were sampled at production platforms (reef and contaminant effects), artificial reefs (reef, but no contaminant effects), platform removal sites (contaminant, but no reef effects), and controls (no contaminants or reef effects), and replicated in three blocks. The removal sites had higher concentrations of many contaminants than reef or control sites, but lower concentrations than platform sites. Reduced meiobenthic abundances and altered Harpacticoida community structure were primarily a function of reef effects, not contaminant effects. The habitat influence is likely a result of complex ecological interactions near platforms. The reef effect appears to be important in controlling meiofauna near platforms where contaminants are low because of drilling and production techniques used in the Gulf of Mexico. The finding that contaminants alone do not explain faunal patterns around offshore platforms indicates that future studies should include appropriate artificial reef control sites.
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MacDonald, Kristi, i Mara Tippett. "Reducing public exposure to common, harmful well water contaminants through targeted outreach to highly susceptible neighborhoods as a method of increasing the likelihood of testing and treatment of water from private wells". Journal of Water and Health 18, nr 4 (8.07.2020): 522–32. http://dx.doi.org/10.2166/wh.2020.059.
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Abstract While the Safe Drinking Water Act mandates testing of public water supplies in the USA, private well owners are responsible for testing and treating their own water. A small percentage of well owners perform annual testing as recommended and many never test at all for common and potentially harmful groundwater contaminants. Finding effective ways to inform residents of the risks associated with their private well drinking water and promote the testing and treatment for common contaminants is a challenge faced by federal, state, and local agencies concerned with public health. Targeting residents whose wells are most at risk for having levels of regulated contaminants above the drinking water standard is a potential way to efficiently reach individuals. Results of this study show that individuals who receive specific letters that a contaminant in a neighbor's well had exceeded the maximum contaminant levels for one of five common well water contaminants (arsenic, radon, Gross Alpha, Escherichia coli, and nitrates) were more likely to test their well than were individuals who received a general letter about common contaminants in the region. Outreach that reports more localized, specific information on contaminants in well water results in an increased chance of testing when compared with more regional and generalized contaminant information.
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Liu, Shuming, Han Che, Kate Smith i Tian Chang. "Contaminant classification using cosine distances based on multiple conventional sensors". Environmental Science: Processes & Impacts 17, nr 2 (2015): 343–50. http://dx.doi.org/10.1039/c4em00580e.
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This paper proposes a new contaminant classification method to discriminate contaminants in a real time manner, independent of the contaminant concentration. The proposed method quantifies the similarities or dissimilarities between sensors' responses to different types of contaminants. The performance of the proposed method was evaluated using data from injection experiments and compared with a Euclidean distance-based method.
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Callen, Cheryl, Jatinder Bhatia, Laura Czerkies, William Klish i George Gray. "Challenges and Considerations When Balancing the Risks of Contaminants with the Benefits of Fruits and Vegetables for Infants and Toddlers". Nutrients 10, nr 11 (24.10.2018): 1572. http://dx.doi.org/10.3390/nu10111572.
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Background: Fruits and vegetables are key to a healthy diet, particularly in children; however, parents may be concerned about contaminants found in fruits and vegetables. Making informed food choices for children requires understanding and balancing the risks of contaminant exposure with the importance of providing a healthy diet. The objective of this work is to identify fruits and vegetables commonly consumed by infants and toddlers; identify potential contaminants in fruits and vegetables; and outline considerations in assessing contaminant risks in food categories with a critical role in a healthy diet. Method: Commonly consumed fruits and vegetables were obtained from the Feeding Infants & Toddlers Study (FITS 2016). The US Food and Drug Administration Total Diet Study was reviewed for contaminant occurrence, and multiple experts were consulted on considerations in assessing risk of certain contaminants. Results: FITS data show eight fruits and nine vegetables account for over 80% of consumption in infants and toddlers. Several contaminants have been detected in fruits and vegetables. Questions to be addressed prior to establishing contaminant guidance were identified. Conclusion: Contaminant guidance for fruits and vegetables consumed by infants and toddlers raises several challenges. Expertise from multiple disciplines is required to find an approach that maximizes public health benefit.
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Kaag, N. H. B. M., E. M. Foekema i M. C. Th Scholten. "Ecotoxicity of contaminated sediments, a matter of bioavailability". Water Science and Technology 37, nr 6-7 (1.03.1998): 225–31. http://dx.doi.org/10.2166/wst.1998.0756.
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Marine and freshwater mesocosm-scale experiments with contaminated sediments have shown that there is a direct relationship between the accumulated contaminant levels and the feeding habits of the organisms used. The highest levels of PAHs and PCBs were found in the sediment feeding lugworm Arenicola marina and in Tubifex worms. The levels of contaminants in the suspension feeding mussels Mytilus edulis and the zebra mussels, Dreissena polymorpha, were not influenced by the contaminant content of the sediments, but were related instead to the level of contaminants in the sea water above. Intermediate levels were found in the baltic tellin, Macoma balthica, which is a filter feeder as well as a deposit feeder, depending on the availability of food. These results show that there is no simple relationship between contaminant concentration in the sediments and bioavailability. Higher levels of contaminants do not necessarily lead to higher levels of these contaminants in Arenicola, due to differences in the sediment structure and the ageing of the contamination. On the other hand, toxic effects are related to the internal concentrations of certain chemicals. The internal concentrations observed in Arenicola may provide a good estimation of the true bioavailability of sedimentary contaminants and can also be used as an indicator for potential environmental effects.
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Chappell-Campbell, Laura, Hayden T. Schwenk, Nicole Capdarest-Arest i Alan R. Schroeder. "Reporting and Categorization of Blood Culture Contaminants in Infants and Young Children: A Scoping Review". Journal of the Pediatric Infectious Diseases Society 9, nr 2 (13.12.2018): 110–17. http://dx.doi.org/10.1093/jpids/piy125.
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Abstract Background Blood cultures are obtained routinely for infants and young children for the evaluation for serious bacterial infection. Isolation of organisms that represent possible contaminants poses a management challenge. The prevalence of bacteremia reported in this population is potentially biased by inconsistent contaminant categorization reported in the literature. Our aim was to systematically review the definition and reporting of contaminants within the literature regarding infant bacteremia. Methods A search of studies published between 1986 and mid-September 2016 was conducted using Medline/PubMed. Included studies examined children aged 0 to 36 months for whom blood culture was performed as part of a serious bacterial infection evaluation. Studies that involved children in an intensive care unit, prematurely born children, and immunocompromised children or those with an indwelling catheter/device were excluded. Data extracted included contaminant designation methodology, organisms classified as contaminants and pathogens, and contamination and bacteremia rates. Discussion Our search yielded 1335 articles, and 69 of them met our inclusion criteria. The methodology used to define contaminants was described in 37 (54%) study reports, and 16 (23%) reported contamination rates, which ranged from 0.5% to 22.8%. Studies defined contaminants according to organism species (n = 22), according to the patient’s clinical management (n = 4), and using multifactorial approaches (n = 11). Many common organisms, particularly Gram-positive cocci, were inconsistently categorized as pathogens or contaminants. Conclusions Reporting and categorization of blood culture contamination are inconsistent within the pediatric bacteremia literature, which limits our ability to estimate the prevalence of bacteremia. Although contaminants are characterized most frequently according to organism, we found inconsistency regarding the classification of certain common organisms. A standardized approach to contaminant reporting is needed.
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Wang, Rong Guang, Mitsuo Kido, Suketsuku Nakanishi i Takuji Okabe. "Observation and Removal of Atmospheric Micro-Contaminants on SUS304 Steel". Advanced Materials Research 189-193 (luty 2011): 876–80. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.876.
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Micro-contaminants on SUS304 stainless steel were observed and confirmed by atomic force microscope, and the micro-contaminant removal was carried out by ultraviolet (UV) illumination. The amount of micro-contaminants on the specimen surface decreased with an increase in the UV illumination time, with extensive removal of the organic substance in the contaminants but leaving part of the contained water in the contaminants. The surface for macro-droplets after the UV illumination became hydrophilic, while no large change of the wettability for micro-droplets on the same surface can be observed.
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Morrill, A., J. F. Provencher i M. R. Forbes. "Testing for dual impacts of contaminants and parasites on hosts: the importance of skew". Environmental Reviews 22, nr 4 (grudzień 2014): 445–56. http://dx.doi.org/10.1139/er-2014-0026.
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A review of recent studies published over a 23-year timespan (1990–2012) showed rapidly increasing interest in exploring how environmental contaminants and parasitism might influence each other and (or) interact to affect host health. Those experimental and observational studies fall into three broad categories (comparative studies of the possible influence of each factor on the other, correlative studies between contaminants and parasitism, and studies on relative bioaccumulation of contaminants by parasites versus their hosts). Despite the exponential increase in relevant studies, little attention has been paid to how contaminants and parasitism should co-occur among individuals within host populations and (or) how the nature of co-distributions should be incorporated into study designs and analyses. Null expectations of co-distributions between contaminants and parasitism can be derived from underlying distributions of each factor. Using a subset of studies, we found contaminant distributions showed positive skew in about one third of cases testing for correlations between contaminant concentrations and parasitism among hosts. We show such skew is expected for theoretical reasons. We used this information to guide simulations wherein the oft-cited negative binomial distribution of parasitism (also supported by theory) was combined with both log-normal (skewed) and normal distributions of contaminants to generate expected null co-distributions. Simulations demonstrated an increasingly concave (or L-shaped) co-distribution with increasing contaminant positive skew: proportionately more individuals experience low levels of each factor while few to none experienced high contaminant and high parasite burdens simultaneously. Our results have the following implications: they call into question experimental studies exposing specimens to parasites and pollutants at levels higher than, or even equal to, observed averages, and they provide a framework for exploring how individual-based effects might scale up into effects at the population level. Potential improvements to study designs and (or) statistical tests are offered that recognize the need to understand the underlying distributions of both contaminants and parasitism and the degree to which one can infer host population effects.
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Thompson, Alesha K., Michele M. Monti i Matthew O. Gribble. "Co-Occurrence of Metal Contaminants in United States Public Water Systems in 2013–2015". International Journal of Environmental Research and Public Health 18, nr 15 (26.07.2021): 7884. http://dx.doi.org/10.3390/ijerph18157884.
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The United States Environmental Protection Agency monitors contaminants in drinking water and consolidates these results in the National Contaminant Occurrence Database. Our objective was to assess the co-occurrence of metal contaminants (total chromium, hexavalent chromium, molybdenum, vanadium, cobalt, and strontium) over the years 2013–2015. We used multilevel Tobit regression models with state and water system-level random intercepts to predict the geometric mean of each contaminant occurring in each public water system, and estimated the pairwise correlations of predicted water system-specific geometric means across contaminants. We found that the geometric means of vanadium and total chromium were positively correlated both in large public water systems (r = 0.45, p < 0.01) and in small public water systems (r = 0.47, p < 0.01). Further research may address the cumulative human health impacts of ingesting more than one contaminant in drinking water.
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Nieveen, Wesley. "Methods To Identify Contaminants On Photoresists". Microscopy Today 6, nr 4 (maj 1998): 6–8. http://dx.doi.org/10.1017/s1551929500067171.
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Contaminants on photoresist can be difficult to identify, especially if they are very thin, e.g., less than 0.5 μm. It is very doubtful at the 0.2 μm realm that histological or optical microscopy methods will work, There are several methods available to identify such contaminants1 each giving different degrees or type of information about contaminants.
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Taylor, W. D., J. H. Carey, D. R. S. Lean i D. J. McQueen. "Organochlorine Concentrations in the Plankton of Lakes in Southern Ontario and Their Relationship to Plankton Biomass". Canadian Journal of Fisheries and Aquatic Sciences 48, nr 10 (1.10.1991): 1960–66. http://dx.doi.org/10.1139/f91-233.
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Hydrophobic organochlorine contaminants were surveyed in net plankton from 33 lakes in southern Ontario. Organochlorines were detected in all lakes. The relative concentrations of 12 common organochlorines were generally similar, suggesting that they derive from a common source, probably atmospheric transport. Variability in relative abundances of these contaminants increased with contaminant concentration, while contaminant concentration was related to plankton biomass, total phosphorus, and conductivity. Lakes with low plankton biomass had high organochlorine concentrations in that biomass, indicating that a large portion of the variation among lakes in the concentration of contaminants in plankton can be ascribed to variable planktonic biomass. This negative relationship with plankton biomass, or biomass dilution effect, was strongest for the more hydrophobic and refractory compounds.
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Puangngernmak, N., i S. Chalermwisutkul. "Characterization of Heavy Metal Contaminated Wastewater Using a Coaxial Sensor and Electromagnetic Wave Reflection Technique". Applied Mechanics and Materials 548-549 (kwiecień 2014): 678–82. http://dx.doi.org/10.4028/www.scientific.net/amm.548-549.678.
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Industrial wastewater control is an important issue for protection of the environment. Liquid characterization using radio frequency signal is an interesting approach for selective detection of heavy metal contaminants in industrial wastewater. A simple sensor based on open-ended coaxial structure filled with the liquid under test is proposed. Liquid samples for the experiments are copper, zinc and nickel solutions with various concentrations of 1, 10, 100 and 1000 mg/liter each. From the measurement results using a vector network analyzer (VNA) in combination with the proposed sensor, the concentration of a specific contaminant can be determined by the magnitude of the measured reflection coefficient in a frequency range lower than 2 GHz. Applying a capacitive model of the sensor, complex permittivity of the liquid under test can be calculated from the measured reflection coefficient. Obvious relationship between the imaginary part of complex permittivity and the concentration of contaminant in a frequency range lower than 2 GHz was observed. The type of contaminants in the liquid samples can be identified by the position of the resonant peaks when the magnitude of reflection coefficient is plotted in the spectrum. The frequency range for contaminant’s identification lies between 2 and 3 GHz.
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Conn, Jeffery S. "Pathways of Invasive Plant Spread to Alaska: III. Contaminants in Crop and Grass Seed". Invasive Plant Science and Management 5, nr 2 (czerwiec 2012): 270–81. http://dx.doi.org/10.1614/ipsm-d-11-00073.1.
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AbstractInvasive plants disperse to new areas via numerous pathways. Study of these pathways helps to focus limited budgets toward prevention and early detection. This study examined potentially invasive seed contaminants in imported crops and grass seed as pathways for plant dispersal to Alaska. Crop and grass seed were purchased from 13 Alaska retail outlets representing 14 seed suppliers. Seed bags were sampled using federally mandated protocols and were analyzed for crop seeds that were not supposed to be included and for weed contaminants. Ninety-five weed and 36 contaminant crop taxa were found. Crop seed contained 43 weed taxa and 15 other crop species contaminants, a mean of 6.4 taxa and 3,844 contaminant seed kg−1. Grass seed samples contained 73 weed taxa and 21 crop contaminants, a mean of 3.5 contaminant species and 1,250 seeds kg−1. Two species prohibited by the Alaska seed law were found: Canada thistle was found in a single crop sample, and quackgrass was found in two grass samples. There were no significant relationships between either seed type or supplier and either the number of contaminant species or number of seeds. Labels of 33% of crop samples and 8% of grass samples claimed 0.00% weed seeds, but low (0.007% by weight, 2 species) to high (1.18% by weight, 13 species) amounts of weed contaminants were found. Importation of crop seed is a large pathway for seed movement, causing significant propagule pressure and an increased likelihood of establishment by new invasive plant populations. Prevention of spread via this pathway would be enhanced by changes to seed laws, by greater regulatory enforcement, and by including on the label, the names of all weed and contaminant crop species found in the law-required samples. Consumers could then make decisions on whether to purchase seed based on the potentially invasive species that would be planted with the desired seed.
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Melcer, Henryk, Hugh Monteith i Stephen G. Nutt. "Variability of Toxic Trace Contaminants in Municipal Sewage Treatment Plants". Water Science and Technology 20, nr 4-5 (1.04.1988): 275–84. http://dx.doi.org/10.2166/wst.1988.0177.
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The variability of toxic trace contaminants in influents and effluents at three full-scale municipal sewage treatment plants was measured by collecting grab samples of degritted raw wastewater and non-chlorinated secondary effluent at two hour intervals over eight consecutive days. The samples were analyzed for metals, conventional contaminants and a range of organic trace contaminants. The metals and volatile organic compounds were the dominant contaminants found in the influents. In the effluents, organic concentrations were close to detectable levels and polyaromatic hydrocarbons were almost never detected. Some influent metal and organic contaminants varied diurnally while others appeared to fluctuate randomly with periodic spike inputs. The variability of most effluent trace contaminant concentrations was considerably attenuated in comparison to influent concentrations.
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Melcer, H., H. Monteith, M. Newbigging, S. G. Nutt i J. P. Stephenson. "Dynamic Modelling of Trace Contaminant Removal in a Municipal Sewage Treatment Plant". Water Science and Technology 21, nr 4-5 (1.04.1989): 351–62. http://dx.doi.org/10.2166/wst.1989.0237.
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The variability of influent and effluent concentrations of trace contaminants at a full-scale municipal sewage treatment plant (STP) was measured by intensive sampling at two hour intervals for eight consecutive days. From these data, the technique of time series analysis was used to generate predictive models describing the process response. The data indicated that municipal STPs are capable of efficient trace contaminant removal and significantly attenuate the variability of these contaminants in the raw influent. Significant correlations were identified between influent characteristics and effluent concentrations for selected contaminants. For three metals and three trace contaminants, adequate time series models were developed. Such models are valuable tools for the development of strategies to control trace contaminants in discharges from municipal STPs.
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Duncan, William F. A., i Elizabeth M. Neil. "Improving Aquatic Environmental Impact Assessment in Canada – A Northern Case Study". Water Quality Research Journal 22, nr 4 (1.11.1987): 545–58. http://dx.doi.org/10.2166/wqrj.1987.044.
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Abstract This paper presents and applies a conceptual framework which addresses the causal relationships linking contaminant doses with responses in aquatic environments. The paper is focused on metal contaminants and reviews a northern case study in which the framework was applied. The approach emphasizes the environmental factors regulating the potential effects of contaminants and stresses the importance of understanding the physical environmental processes in monitoring design and the selection of linkages between the contaminant dose and the valued ecosystem components.
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Dempsey, B. A., Y. L. Tai i S. G. Harrison. "Mobilization and Removal of Contaminants Associated with Urban Dust and Dirt". Water Science and Technology 28, nr 3-5 (1.08.1993): 225–30. http://dx.doi.org/10.2166/wst.1993.0424.
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The objective of this research was to examine the effects of pH and contaminant/sorbent concentrations on the partitioning of contaminants in urban dust and dirt An emphasis has been placed on the environmental behavior of trace metals. Contaminants in urban dust and dirt are primarily associated with particles, even after suspension in runoff water for several hours to days. This affects the reactivity, toxicity, and mobility of the contaminants. Particle size distributions (PSD) for urban dust and dirt and partition coefficients (Kp) for the distribution of various contaminants between the water and the particles of various sizes are described. Where streams have very low alkalinity or in areas affected by acid precipitation, there can be substantial decrease in pH with dilution of the initial runoff. This has a significant effect on the speciation of contaminants, and therefore on the reactivity and mobility of contaminants in urban runoff.
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Rouel, Melissa, Richard J. Stevenson, Josephine Milne-Home i Evelyn Smith. "Differences in emotions and cognitions experienced in contamination aversion". Journal of Experimental Psychopathology 9, nr 3 (1.07.2018): 204380871879482. http://dx.doi.org/10.1177/2043808718794826.
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A current model of contamination aversion suggests that it has distinct affective and cognitive components that interact to respond to threats. The affective component involves disgust and responds preferentially to direct contaminants (e.g., feces). The cognitive component involves obsessive beliefs and responds preferentially to indirect contaminants (e.g., money). This study examined characteristics of the two components by comparing emotional and cognitive responses to different contaminants. In total, 47 participants completed behavioral avoidance tasks with direct, indirect, and harmful contaminants. Participants rated their disgust, fear of contamination, and threat estimation while in contact with each contaminant. The contaminants produced different emotional and cognitive responses, suggesting the differential involvement of affective and cognitive factors depending on the type of threat. Additionally, it was found that disgust did not habituate over time in contact with contaminants, whereas fear of contamination and threat estimation appeared to decline. Clinical and theoretical implications are discussed.
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Nasirian, Hassan. "Contamination of Cockroaches (Insecta: Blattaria) by Medically Important Bacteriae: A Systematic Review and Meta-analysis". Journal of Medical Entomology 56, nr 6 (20.06.2019): 1534–54. http://dx.doi.org/10.1093/jme/tjz095.
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Abstract Cockroaches have the potential to disseminate bacteria in their environments and therefore a systematic review and meta-analysis was conducted to assess the state-of-the-art of our knowledge regarding bacterial contaminants of cockroaches. At least 78 bacterial species and 42 genera from 24 families and 11 orders of bacteria were reported to have contaminated cockroaches. At least 61, 42, 12, 13, 7, and 16 bacterial species have contaminated Blattella germanica (L.) (Blattaria: Ectobiidae), Periplaneta americana (L.) (Blattaria: Blattidae), Blatta orientalis (L.) (Blattaria: Blattidae), Diploptera punctata (Eschscholtz) (Blattaria: Blaberidae), Periplaneta fuliginosa (Serville) (Blattaria: Blattidae), and Supella longipalpa (F.) (Blattaria: Ectobiidae), respectively. Blattella germanica is the most commonly contaminated cockroach species, with the widest bacterial species diversity that threatens human health, followed by P. americana. Cockroach bacterial contaminants may result in the dissemination of opportunistic or pathogenic infections, particularly nosocomial and foodborne infections. One-way analysis of variance (ANOVA) revealed significant differences between bacterial contaminant species of cockroaches, species of cockroaches with bacterial contaminants, cockroach body part surfaces from the point of view bacterial contaminants and countries of cockroach infested with bacterial contaminants (P < 0.05). This statistical analysis indicates that the bacterial contaminants of the external cockroach body parts are potentially more harmful than from internal surfaces, and secondly, the bacterial contaminants of cockroaches in hospital environments are potentially more harmful than from other human environments. The survey indicated that the bacterial contaminant species of cockroaches appear to be mostly multiple drug resistant. The challenges of cockroaches as being potential vectors of pathogenic or opportunistic agents of human infections are discussed.
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Saaristo, Minna, Tomas Brodin, Sigal Balshine, Michael G. Bertram, Bryan W. Brooks, Sean M. Ehlman, Erin S. McCallum i in. "Direct and indirect effects of chemical contaminants on the behaviour, ecology and evolution of wildlife". Proceedings of the Royal Society B: Biological Sciences 285, nr 1885 (22.08.2018): 20181297. http://dx.doi.org/10.1098/rspb.2018.1297.
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Chemical contaminants (e.g. metals, pesticides, pharmaceuticals) are changing ecosystems via effects on wildlife. Indeed, recent work explicitly performed under environmentally realistic conditions reveals that chemical contaminants can have both direct and indirect effects at multiple levels of organization by influencing animal behaviour. Altered behaviour reflects multiple physiological changes and links individual- to population-level processes, thereby representing a sensitive tool for holistically assessing impacts of environmentally relevant contaminant concentrations. Here, we show that even if direct effects of contaminants on behavioural responses are reasonably well documented, there are significant knowledge gaps in understanding both the plasticity (i.e. individual variation) and evolution of contaminant-induced behavioural changes. We explore implications of multi-level processes by developing a conceptual framework that integrates direct and indirect effects on behaviour under environmentally realistic contexts. Our framework illustrates how sublethal behavioural effects of contaminants can be both negative and positive, varying dynamically within the same individuals and populations. This is because linkages within communities will act indirectly to alter and even magnify contaminant-induced effects. Given the increasing pressure on wildlife and ecosystems from chemical pollution, we argue there is a need to incorporate existing knowledge in ecology and evolution to improve ecological hazard and risk assessments.
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Aminian, Javad, Mehdi Maerefat i Ghassem Heidarinejad. "A new simplified method for decreasing contaminants in underground enclosed parking lots". Building Services Engineering Research and Technology 39, nr 5 (17.04.2018): 590–608. http://dx.doi.org/10.1177/0143624418769446.
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One of the main concerns in large enclosed vehicular spaces such as parking lots is air contaminant management. Mechanical ventilation systems are typically used to decrease the contaminants and enhance indoor air quality in such spaces. International standards have suggested the amount of ventilation air and have emphasized that the ventilation system should be able to effectively reduce the contaminants, but the reduction in contaminants has not been quantitatively described. This study develops a simplified method for the quantification of contaminant removal and its effect on the enhancement of indoor air quality. This method is based on the numerical calculation of contaminant removal effectiveness in parking lots and changing the location of outlet vents. The results of this work indicate that using a constant ventilation rate, outlet vents are installed at an appropriate height, the flow pattern is improved and contaminant removal effectiveness is enhanced significantly. The numerical results show that the outlet vents should be installed between 50 and 70% of the parking lot ceiling height. By adopting this criterion, a displacement flow pattern is developed in the parking lot, and improvement in both contaminant removal effectiveness and indoor air quality is achieved. Practical application: This paper helps ventilation designers to enhance the air quality of enclosed parking lots by a simple practical method. The designer should only install the outlet vents at the range of heights proposed in this paper to develop displacement flow in the parking lot, which leads to an effective decrease in contaminants and reduce energy consumption. So, the aim of this research is to maximize the contaminant removal capacity and minimize the energy consumption of the ventilation system.
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MacLachlan, D. J. "Estimating the transfer of contaminants in animal feedstuffs to livestock tissues, milk and eggs: a review". Animal Production Science 51, nr 12 (2011): 1067. http://dx.doi.org/10.1071/an11112.
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Literature studies on the transfer from livestock feed of residues of organic contaminants, metals and mycotoxins to edible livestock commodities have been reviewed. This review focuses on contaminants relevant to risks assessment of livestock feeds, especially those contaminants for which regulatory standards have been established. Those involved in the supply of livestock feed need to be aware of maximum levels for various contaminants in food and develop strategies to ensure food derived from livestock complies. An impediment to profiling feed ingredients has been the lack of accessible information on the transfer of residues from feed to tissues, milk and eggs derived from exposed livestock. Transfer factors are summarised for 72 contaminants for cattle, sheep, goats, pigs and poultry and can be used in the first tiers of risk assessment to identify contaminant and feed ingredient combinations that require management.
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Hungler, Arnaud, Afaque Momin, Kay Diederichs i Stefan, T. Arold. "ContaMinerand ContaBase: a webserver and database for early identification of unwantedly crystallized protein contaminants". Journal of Applied Crystallography 49, nr 6 (2.11.2016): 2252–58. http://dx.doi.org/10.1107/s1600576716014965.
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Solving the phase problem in protein X-ray crystallography relies heavily on the identity of the crystallized protein, especially when molecular replacement (MR) methods are used. Yet, it is not uncommon that a contaminant crystallizes instead of the protein of interest. Such contaminants may be proteins from the expression host organism, protein fusion tags or proteins added during the purification steps. Many contaminants co-purify easily, crystallize and give good diffraction data. Identification of contaminant crystals may take time, since the presence of the contaminant is unexpected and its identity unknown. A webserver (ContaMiner) and a contaminant database (ContaBase) have been established, to allow fast MR-based screening of crystallographic data against currently 62 known contaminants. The web-basedContaMiner(available at http://strube.cbrc.kaust.edu.sa/contaminer/) currently produces results in 5 min to 4 h. The program is also available in a github repository and can be installed locally.ContaMinerenables screening of novel crystals at synchrotron beamlines, and it would be valuable as a routine safety check for `crystallization and preliminary X-ray analysis' publications. Thus, in addition to potentially saving X-ray crystallographers much time and effort,ContaMinermight considerably lower the risk of publishing erroneous data.
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Manzoni, Stefano, Annalisa Molini i Amilcare Porporato. "Stochastic modelling of phytoremediation". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 467, nr 2135 (22.06.2011): 3188–205. http://dx.doi.org/10.1098/rspa.2011.0209.
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Leaching of heavy metals and other contaminants from soils poses a significant environmental threat as it affects the quality of downstream water bodies. Quantifying these losses is particularly important when employing phytoremediation approaches to reduce soil contamination, as contaminant escaping the system through leaching cannot be taken up by vegetation. Despite its undoubted importance, the role of such hydrologic forcing has seldom been fully considered in models describing the long-term contaminant mass balance during phytoremediation. The partitioning of contaminants between leaching and vegetation uptake is controlled by a number of biophysical processes as well as rainfall variability. Here, we develop a novel stochastic framework that provides analytical expressions to quantify the partitioning of contaminants between leaching and plant uptake and the probability of phytoremediation duration as a function of rainfall statistics and soil and vegetation characteristics. Simple expressions for the mean phytoremediation duration and effectiveness (defined as the fraction of contaminant that is recovered in plant biomass) are derived. The proposed framework can be employed to estimate under which conditions phytoremediation is more efficient, as well as to design phytoremediation projects that maximize contaminant recovery and minimize the duration of the remediation process.
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Rouel, Melissa, Richard J. Stevenson i Evelyn Smith. "Predicting Contamination Aversion Using Implicit and Explicit Measures of Disgust and Threat Overestimation". Behaviour Change 35, nr 1 (19.02.2018): 22–38. http://dx.doi.org/10.1017/bec.2018.6.
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Explicit measures of disgust and threat overestimation have consistently been found to be involved in contamination aversion. However, evidence of the involvement of these factors at the implicit level is mixed, and the role of both responses has not been looked at concurrently. This study aimed to compare the ability of implicit and explicit measures of disgust and threat overestimation to predict contamination aversion and whether this depends on the type of contaminant. Sixty-five participants completed explicit and implicit measures of disgust and threat overestimation, as well as several measures of contamination aversion, including obsessive-compulsive tendencies, and contamination fear and avoidance of contaminants directly associated with disease (direct contaminants) and harmful substances (harm contaminants). It was found that both explicit disgust and explicit threat overestimation predicted contamination-fear obsessive-compulsive tendencies. Explicit disgust predicted contamination fear and avoidance of direct contaminants, whereas explicit threat overestimation predicted contamination fear and avoidance of harm contaminants. The involvement of implicit processes was weak, with some suggestion of difficulty disengaging predicting avoidance of contaminants. Implications for understanding dysfunctional contamination aversion are discussed.
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Castonguay, Martin, Jean-Denis Dutil i Claude Desjardins. "Distinction between American Eels (Anguilla rostrata) of Different Geographic Origins on the Basis of Their Organochlorine Contaminant Levels". Canadian Journal of Fisheries and Aquatic Sciences 46, nr 5 (1.05.1989): 836–43. http://dx.doi.org/10.1139/f89-105.
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This study presents evidence that organochlorine contaminant levels of fish tissues represent a valuable tool for stock discrimination. Variability of concentrations of 15 organochlorine contaminants allowed a discrimination among American eels (Anguilla rostrata) of unknown (captured during the migration down the St. Lawrence River) or known geographic origins. The study also exemplifies that information regarding environmental distribution of contaminants can be gained by comparing organic contaminant levels among groups of fish. Indeed we can infer from this study that mirex contaminated sediments have extensively (at least 400 km) drifted downstream from Lake Ontario in less than 19 yr.
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Kafarowski, Joanna. "Gendered dimensions of environmental health, contaminants and global change in Nunavik, Canada". Études/Inuit/Studies 30, nr 1 (1.08.2007): 31–49. http://dx.doi.org/10.7202/016148ar.
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Abstract As has been well-documented in the scholarly literature over the last two decades, contaminants pose a potentially significant threat to the short and long-term health of Arctic human and natural environments and raise questions of social and environmental justice. Studies link contaminants such as heavy metals, persistent organic pollutants and radionuclides with the use of traditional country foods by Indigenous peoples including the Inuit. Adversely impacting Inuit communities in a myriad of ways, contaminants represent one manifestation of global change across the circumpolar North. Focusing on the community of Inukjuak, Nunavik (Northern Québec), Canada, this paper investigates the roles of Inuit women and men vis-à-vis participation in hunting activities and the identification of contaminants, and demonstrates how women and men construct the lead contaminant issue differently. Additionally, the paper explores why including the perspectives of both is critical to the development of effective environmental health policies, programs and strategies in response to these contaminants.
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Jiang, Guannan, Michelle Crimi, Kathleen Fowler i Xiaojing Fu. "Experimental design of diffusion and desorption of contaminant in heterogeneous media". Water Science and Technology 64, nr 4 (1.08.2011): 988–98. http://dx.doi.org/10.2166/wst.2011.065.
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Storage of contaminants in low permeability media (LPM) presents a great challenge for prediction of remediation effectiveness and efficiency. The reason lies in the contaminants' complex behaviors within heterogeneous media. Both interparticle and intraparticle diffusion contribute to the difficulty of precise site assessment. Sorption of contaminants – especially within LPM – may sequester the contaminants from active treatment, while desorption over a long period of time leads to contaminant release from storage and consequent re-contamination. Research has been conducted toward better understanding of contaminant diffusion and sorption/desorption processes to better predict contaminant response to site treatment. However, most of the research has been carried out within homogeneous media, while real scenarios in environmental problems feature media whose permeability and other characteristics vary significantly over the treatment volume. Further, few efforts have combined the interparticle/intraparticle diffusion and sorption/desorption processes together. This research aims at a feasible experimental design of diffusion and desorption of contaminant in heterogeneous media to address the gaps in previous research. A 2-D experimental system was designed to evaluate interparticle/intraparticle diffusion processes of trichloroethylene (TCE) in heterogeneous media. The 2-D system was modified to include organic matter in media for simulation of sorption/desorption processes. Results of the research will improve the understanding of how these different transport processes act together within heterogeneous media. Results will also allow for the evaluation of the impact of contaminant mass transport from within low permeability media at a potential treatment site and can support the development of mathematical tools/models combining interparticle/intraparticle and sorption/desorption processes. Such a model will promote more accurate site assessment and provide more confidence in the choice of an effective, economically optimized remediation strategy.
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Chapman, Robert W., i Louis J. Guillette. "Contaminants and impoSEX: transcriptomics of contaminant-induced sex change". Molecular Ecology 22, nr 6 (marzec 2013): 1485–87. http://dx.doi.org/10.1111/mec.12254.
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Chekol, Tesema, Lester R. Vough i Rufus L. Chaney. "Plant-Soil-Contaminant Specificity Affects Phytoremediation of Organic Contaminants". International Journal of Phytoremediation 4, nr 1 (styczeń 2002): 17–26. http://dx.doi.org/10.1080/15226510208500070.
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Goodings, Deborah J. "An examination of rapid, centrifuge physical modeling studies of contaminant movement in freezing soil". Polar Record 35, nr 192 (styczeń 1999): 11–18. http://dx.doi.org/10.1017/s0032247400026280.
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AbstractThis paper reviews the complex factors interacting in the movement of contaminants in soil subject to seasonal freezing. This includes those relevant to the soil itself, the contaminant itself, and environmental factors, all of which must be understood for prediction and effective design of remediation. Numerical modelers, as well as laboratory researchers examining behavior of small elements of the soil system, require reliable information on the range of full-scale system responses, but it is not feasible to acquire this by full-scale tests. Even field workers benefit from this information in planning data collection. Small physical models of contaminants moving through soil have routinely been limited in their usefulness because of differences in model fluid pressures and soil stresses, compared to full-scale conditions. However, small-scale centrifuge modeling presents the opportunity to produce correct and rapid physical simulation of full-scale system response using field soil and real contaminants, under the range of different boundary conditions. This paper discusses the existing recent centrifuge modeling work that supports the thesis that the technique can be applied to understanding and analyzing this complex problem. Five studies are reviewed: one on simulation of soil freezing effects in the absence of contaminants; three on the simulation of contaminant movement through saturated and unsaturated unfrozen soil, and heat transport effects through the fluid phase of unfrozen soils; and one that simulates the combination of contaminant movement in freezing soil.
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Buchanan, C., I. Chung i D. Dunn-Rankin. "A Numerical Study of Indoor Contaminant Mixing". Journal of the IEST 38, nr 5 (1.09.1995): 15–21. http://dx.doi.org/10.17764/jiet.2.38.5.725g821363n26725.
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Indoor air quality depends on the concentration and distribution of airborne contaminants. Often these are not uniform throughout the environment because the inlet air may not mix completely with the room air to dilute contaminants, which can be the result of poor room design or nonequilibrium conditions. The structure of the airflow and the extent of contaminant mixing depends on the location of flow and contaminant sources and sinks, as well as on the geometric barriers in the room. This paper describes a three-dimensional numerical simulation of the transport and dispersion of a passive, airborne contaminant in which the Navier-Stokes and concentration equations are solved under transient conditions for a rectangular enclosure with a single ventilation inlet and outlet. This investigation focuses on the effects of flow obstructions and ventilation rates on contaminant mixing.
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Oratmangun, Kristina M., Dingse Pandiangan i Febby E. Kandou. "Deskripsi Jenis-Jenis Kontaminan Dari Kultur Kalus Catharanthus roseus (L.) G. Donnaman". Jurnal MIPA 6, nr 1 (15.06.2017): 47. http://dx.doi.org/10.35799/jm.6.1.2017.16154.
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Penelitian deskripsi jenis-jenis kontaminan dari kultur kalus Catharanthus roseus telah dilakukan. Penelitian ini bertujuan untuk mendeskripsikan jenis-jenis kontaminan yang terdapat pada kultur kalus C.roseus. Penelitian ini dilaksanakan dua tahap. Tahap pertama dilakukan kultur kalus C. roseus. Kultur kalus menggunakan media MS (Murashige dan Skoog) dengan zpt 2,4 D 2 mg/L dan kinetin 0,2 mg/L. Tahap kedua dilakukan pengamatan kultur kalus yang mengalami kontaminasi. Kontaminan-kontaminan yang sama secara kasat mata dikelompokan menjadi satu kelompok. Setiap kelompok yang sama diamati lebih lanjut dibawah mikroskop. Penentuan jenis kontaminan dibandingkan dengan morfologi dari Pustaka (rujukan). Pengamatan kontaminan dilakukan mulai dari pembuatan media, inokulasi, subkultur kalus C.roseus. Pengamatan dilakukan dengan 3 botol kontaminan dari setiap kelompok. Hasil yang diperoleh adalah kontaminan kultur kalus C. roseus sekitar 40 %. Jenis kontaminan yang diamati umumnya golongan jamur. Jenis-jenis kontaminan kultur kalus C. roseus adalah Rhizopus, Mucor, Aspergillus, dan Sacharomyces.Research description of the types of contaminant for cultured callus Catharanthus roseus has been done. This research aimed describe the types of contaminant found in the cultured kalus C. roseus. This research is carried out in two stages. The first stage in callus culture C. roseus using media MS (Murashige and Skoog) with zpt 2,4 D mg/L and kinetin 0,2 mg/L. The second stage in the observation of contaminated callus culture. The same of contaminants are visible into one group. Each of the same group was observed further under a microscope. Determining the types of contaminant in comparison with reference from the literature. Observation are starting from media or inoculation, subcallus culture C. roseus. Observation done by taking 3 bottles of contaminat from each group then observed for 7 days. The result obtained are culture contaminants C. roseus about 40 %. The types of contaminant observed are generally of fungi. The types of contaminant callus culture C. roseus are Rhizopus, Mucor, Aspergillus, and Sacharomyces.
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Galindo-Miranda, J. Manuel, Cecilia Guízar-González, Elías J. Becerril-Bravo, Gabriela Moeller-Chávez, Elizabeth León-Becerril i Ramiro Vallejo-Rodríguez. "Occurrence of emerging contaminants in environmental surface waters and their analytical methodology – a review". Water Supply 19, nr 7 (10.06.2019): 1871–84. http://dx.doi.org/10.2166/ws.2019.087.
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Abstract A new concern about surface water quality is the occurrence of emerging contaminants that have being recognized as a new class of water contaminants such as antibiotics, hormones, pesticides, personal care products and pharmaceutical products. The occurrence of these contaminants in the aquatic environment and especially in surface water is a serious concern because this is usually the source of water for drinking water treatment plants (DWTP). This review provides a summary of the occurrence and the analytical methodology (extraction process, chromatography analysis, detection systems and ionization source) of emerging contaminant analysis in surface waters including rivers, lakes, creeks and wetlands for their analysis.
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Vanderslice, Robert R., Jennifer Orme, Edward V. Ohanian i Cynthia Sonich-Mullin. "Problems in Assessing the Risks of Mixtures of Contaminants in Drinking Water". Toxicology and Industrial Health 5, nr 5 (grudzień 1989): 747–55. http://dx.doi.org/10.1177/074823378900500512.
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In conducting risk assessments on drinking water contaminants, the U. S. Environmental Protection Agency (EPA) attempts to evaluate all available toxicity data to develop Health Advisory (HA) and Maximum Contaminant Level Goal (MCLG) values. The EPA often has grappled with the issues surrounding the toxic ity of chemical mixtures, including radioactive contaminants, nitrate/nitrite, and trihalomethanes (THMs). In evaluating the tox icity of chemical mixtures, the EPA's immediate concern is whether the individual HA values and MCLGs are protecting public health when multiple contaminants are present in drinking water. Poten tial toxic interactions between drinking water contaminants are dif ficult to predict because experimental studies are generally performed only at high doses relative to environmental levels. Although the contamination of drinking water involves mixtures of contaminants, drinking water regulations are generally based on an assessment of the risks of individual contaminants. This paper dis cusses three issues of major concern to the EPA: the synergistic effects of solvent mixtures, vehicle effects in laboratory studies, and setting standards for essential trace nutrients where the absorption and/ or toxicity are affected by an individual's nutritional status or other dietary components.
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Karmanova, Svetlana, Sergey Melnikov, Alexey Shiryaev i Anton Nurtdinov. "DEVELOPMENT OF EFFICIENT WASHING TECHNOLOGY OF PARTS, MEETING SAFETY REQUIREMENTS DUE TO THE APPLICATION OF WATER-BASED WASHING SOLUTIONS". Perm National Research Polytechnic University Aerospace Engineering Bulletin, nr 64 (2021): 5–15. http://dx.doi.org/10.15593/2224-9982/2021.64.01.
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In the manufacture of parts, surfaces are contaminated due to the peculiarities of the technology. Safe cleaning of these surfaces is an urgent problem. The article discusses non-refractory solutions for cleaning parts. The methodology for carrying out research on cleaning pollution is presented. The following contaminants were chosen: preservation oil K-17, Mobil 423 oil, SOZh-073, Vacuquench B244 quenching oil, Polishing paste, MPK emulsion. The quality of cleaning the contaminants was tested for the following detergents: Ardrox 6378 A, Ardrox 6333, Ardrox 6486. Detergent Ardrox 6378A washes away all investigated contaminants from the surface of the samples, except for conservation oil. Ardrox 6333 B detergent does not wash stubborn contaminants – K-17 conservation oil and polishing paste. The Ardrox 6486 detergent composition does not wash all investigated contaminants except the IPC emulsion. Of the Ardrox brand detergents, Ardrox 6378A is the most effective. Studies have been conducted to determine the optimal contaminant cleaning regime for the most effective detergent composition – Ardrox 6378A. The study showed that at a concentration of this composition of 15 % and a temperature of 65 °C, the surface is washed from all contaminants.
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Riding, M. J., F. L. Martin, K. C. Jones i K. T. Semple. "Carbon nanomaterials in clean and contaminated soils: environmental implications and applications". SOIL Discussions 1, nr 1 (20.06.2014): 151–99. http://dx.doi.org/10.5194/soild-1-151-2014.
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Abstract. The exceptional sorptive ability of carbon nanomaterials (CNMs) for hydrophobic organic contaminants (HOCs) is driven by their characteristically large reactive surface areas and highly hydrophobic nature. Given these properties, it is possible for CNMs to impact on the persistence, mobility and bioavailability of contaminants within soils, either favourably through sorption and sequestration, hence reducing their bioavailability, or unfavourably through increasing contaminant dispersal. This review considers the complex and dynamic nature of both soil and CNM physicochemical properties to determine their fate and behaviour, together with their interaction with contaminants and the soil micro-flora. It is argued that assessment of CNMs within soil should be conducted on a case-by-case basis, and further work to assess the long-term stability of sorbed contaminants and the toxicity of CNMs is required before their sorptive abilities can be applied to remedy environmental issues.
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Nerenberg, R., i B. E. Rittmann. "Hydrogen-based, hollow-fiber membrane biofilm reactor for reduction of perchlorate and other oxidized contaminants". Water Science and Technology 49, nr 11-12 (1.06.2004): 223–30. http://dx.doi.org/10.2166/wst.2004.0847.
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Many oxidized pollutants, such as nitrate, perchlorate, bromate, and chlorinated solvents, can be microbially reduced to less toxic or less soluble forms. For drinking water treatment, an electron donor must be added. Hydrogen is an ideal electron donor, as it is non-toxic, inexpensive, and sparsely soluble. We tested a hydrogen-based, hollow-fiber membrane biofilm reactor (MBfR) for reduction of perchlorate, bromate, chlorate, chlorite, chromate, selenate, selenite, and dichloromethane. The influent included 5 mg/L nitrate or 8 mg/L oxygen as a primary electron accepting substrate, plus 1 mg/L of the contaminant. The mixed-culture reactor was operated at a pH of 7 and with a 25 minute hydraulic detention time. High recirculation rates provided completely mixed conditions. The objective was to screen for the reduction of each contaminant. The tests were short-term, without allowing time for the reactor to adapt to the contaminants. Nitrate and oxygen were reduced by over 99 percent for all tests. Removals for the contaminants ranged from a minimum of 29% for chlorate to over 95% for bromate. Results show that the tested contaminants can be removed as secondary substrates in an MBfR, and that the MBfR may be suitable for treating these and other oxidized contaminants in drinking water.
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Bonfim, Osmar Toledo, Denilson Burkert, Mariana Ribeiro Fernandes i Alan Lima dos Reis. "Análise da distribuição espacial e evolução do número de áreas contaminadas nas bacias hidrográficas dos rios Aguapeí e Peixe". Research, Society and Development 10, nr 8 (9.07.2021): e14710817264. http://dx.doi.org/10.33448/rsd-v10i8.17264.
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Área contaminada é definida como área, terreno, local, instalação ou edificação que contenha quantidades, ou concentrações de matéria, em condições que causem ou possam causar danos à saúde humana, meio ambiente ou a outro bem a proteger. Buscando obter um melhor entendimento a respeito das áreas contaminadas nas bacias hidrográficas do rio Aguapeí e do rio do Peixe (BHAP), o objetivo deste trabalho foi realizar o levantamento das áreas contaminadas nas BHAP, identificar as principais atividades potencialmente contaminantes e os meios físicos mais afetados, e simultaneamente, correlacionar os possíveis valores de contaminação com os parâmetros socioeconômicos dos respectivos municípios. Foram utilizados dados de áreas contaminadas no período de 2007 à 2019 dos municípios pertencentes às BHAP, obtidos através dos Relatórios de Áreas Contaminadas e Reabilitadas do Estado de São Paulo publicados pela Companhia Ambiental do Estado de São Paulo. Foram identificados 26 municípios com áreas contaminadas, sendo os postos de combustíveis a principal atividade contaminante, enquanto os solventes aromáticos e os hidrocarbonetos policíclicos aromáticos foram os contaminantes mais relatados. As águas subterrâneas e os subsolos foram, majoritariamente, os meios mais impactados pelos contaminantes. Uma correlação forte foi encontrada entre o maior número de contaminantes e as cidades com maior área e também com maior número de habitantes. De modo geral, a identificação dos locais contaminados em bacias hidrográficas configura-se como uma importante ferramenta que visa auxiliar no gerenciamento das áreas contaminadas e na adoção de ações mitigatórias e a produção de políticas públicas que visem amenizar os efeitos das contaminações.
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Campbell, I. B., D. S. Sheppard i G. G. C. Claridge. "Relationships and significance of contaminants in soils of the Transantarctic Mountains". Polar Record 39, nr 4 (październik 2003): 301–8. http://dx.doi.org/10.1017/s0032247402002851.
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The behaviour of Antarctic soils towards contaminant materials depends on the nature of the contaminant and the properties of the soil. Relevant properties are: depth to permafrost, whether the permafrost is ice-cemented or dry frozen; the active layer depth, active layer moisture content, and frequency of liquid water; soil salinity characteristics; and the geological composition of the soil materials.Soil contaminations in the McMurdo region have been investigated through several years in a number of studies, including site surveys, field investigations, and experiments. Results of these studies are summarized in this paper and the significance of the contaminations is discussed. The behaviour of contaminants at the sites investigated conforms to existing knowledge of the soil properties. In the presence of some summer water or occasional moisture influxes from snowmelt, soluble contaminants may be transported variable distances through soils, both downwards and laterally, depending on the amount of water available. Ice-cemented permafrost restricts the downward movement of most contaminants but may aid distribution via lateral flow, especially low-freezing-point contaminants such as hydrocarbons. In dry-frozen soils, low-freezing-point contaminants may penetrate deeply into the soil.With respect to the sites investigated, the heavy metal contaminations were typically above the values from undisturbed sites, but there may at times be appreciable natural variation. The presence of solid materials in soils — such as particles of plastics, wood, fibre, etc — represents a widespread and pernicious form of contamination, because they are foreign to the environment and are non-degradable.
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De Leon, Ricardo. "Virulence factor–activity relationships: workshop summary". Journal of Water and Health 7, S1 (1.08.2009): S94—S100. http://dx.doi.org/10.2166/wh.2009.072.
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The concept or notion of virulence factor–activity relationships (VFAR) is an approach for identifying an analogous process to the use of qualitative structure–activity relationships (QSAR) for identifying new microbial contaminants. In QSAR, it is hypothesized that, for new chemical contaminants, their potential acute or chronic toxicity may be reasonably estimated on the basis of structural relationships to other known toxic contaminants. Thus the parallel that is being attempted for pathogenic microorganisms is that known virulence factors may be used as predictors for identifying undiscovered pathogens and microbial causes of emerging diseases. Advances in molecular biology, genomics and proteomics have led the Committee on Drinking Water Contaminants of the National Research Council, as requested by the EPA, to recommend the VFAR approach as a potentially more systematic and scientific process for the selection of microorganisms for inclusion in the Contaminant Candidate List (CCL).
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Riding, M. J., F. L. Martin, K. C. Jones i K. T. Semple. "Carbon nanomaterials in clean and contaminated soils: environmental implications and applications". SOIL 1, nr 1 (5.01.2015): 1–21. http://dx.doi.org/10.5194/soil-1-1-2015.
Pełny tekst źródłaStreszczenie:
Abstract. The exceptional sorptive ability of carbon nanomaterials (CNMs) for hydrophobic organic contaminants (HOCs) is driven by their characteristically large reactive surface areas and highly hydrophobic nature. Given these properties, it is possible for CNMs to impact on the persistence, mobility and bioavailability of contaminants within soils, either favourably through sorption and sequestration, hence reducing their bioavailability, or unfavourably through increasing contaminant dispersal. This review considers the complex and dynamic nature of both soil and CNM physicochemical properties to determine their fate and behaviour, together with their interaction with contaminants and the soil microflora. It is argued that assessment of CNMs within soil should be conducted on a case-by-case basis and further work to assess the long-term stability and toxicity of sorbed contaminants, as well as the toxicity of CNMs themselves, is required before their sorptive abilities can be applied to remedy environmental issues.
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Yang, Lin, Xiangdong Li, Yihuan Yan i Jiyuan Tu. "Effects of cough-jet on airflow and contaminant transport in an airliner cabin section". Journal of Computational Multiphase Flows 10, nr 2 (7.12.2017): 72–82. http://dx.doi.org/10.1177/1757482x17746920.
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The goals of this study were to investigate the effect of cough-jet on local airflow and contaminant transport in a typical cabin environment by using computational fluid dynamics. A fully occupied airliner cabin section was employed as the computational domain. Contaminants were released through coughing passengers from different locations inside the cabin. Numerical results in terms of contaminant transport characteristics were examined and compared. It can be concluded that cough-jet has significant effects on air flow in front of cough passenger in a short period of time. Also, it was found that, without considering the cough-jet model, the simulation results could not be a precise representation of the transport and distribution of cough-generated airborne contaminants.
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Kadmi, Yassine, Lidia Favier, Mouni Lotfi, Noureddine Nasrallah i Dominique Wolbert. "A highly sensitive liquid chromatography-tandem mass spectrometry method for the analysis of a toxic water disinfection by-product, N-nitrosomethylethylamine". Anal. Methods 6, nr 10 (2014): 3231–34. http://dx.doi.org/10.1039/c4ay00146j.
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Chen, Fei, William B. Anderson i Peter M. Huck. "An approach for determining the most critical among a suite of chemical contaminants at a drinking water intake". Water Supply 13, nr 3 (1.05.2013): 835–45. http://dx.doi.org/10.2166/ws.2013.075.
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An integrated approach for the identification and assessment of the most critical chemical contaminant(s) at a drinking water intake has been developed. It involves the determination of a threshold or critical raw water concentration (CRWC) for target contaminants using the observed overall removal efficiency of a specific water treatment plant (WTP) and regulated drinking water concentrations for the target contaminants. The exceedance probability relative to the CRWC based on historical raw water quality monitoring data is then calculated. Finally, the integration of the raw water quality data and the overall efficiency of a particular WTP sequence allows for identification of the most critical contaminant(s) as well as an advance indication of which contaminants are most likely to challenge a plant. The proactive nature of this approach gives a utility the impetus and time to assess current treatment processes and potential alternatives. In addition, it was found that three- or four-parameter theoretical distributions are more appropriate than two-parameter probability distributions for the fitting of raw water quality data. This study reveals that the reliance on raw and/or treated water contaminant concentrations in isolation or on theoretical removals through treatment processes can, in some circumstances, be misguided.
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Kline, Ahnika, Harry Porterfield i A. Zelazny. "661. Futility of Bacterial Bone Marrow Cultures: Experience over a 19 Year Period". Open Forum Infectious Diseases 7, Supplement_1 (1.10.2020): S386. http://dx.doi.org/10.1093/ofid/ofaa439.854.
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Abstract Background Bone marrow biopsies are often performed on patients with unclear diagnoses and cultures may be ordered for both routine bacterial, mycobacterial and fungal pathogens. They are performed in semi-sterile conditions and involve needle penetration through the skin, posing an increased risk of skin contamination. These cultures also require a substantial amount of laboratory personnel time. Methods Cultures collected from 2001-2020 were surveyed in the lab electronic record. We assessed the culture type (fungal, bacterial, mycobacterial), and the presence of pathogens and contaminants. An organism was deemed a contaminant if it was consistent with skin flora or listed as a contaminant in the report given to the physician. Organisms for which the role in bone marrow disease is unclear were included as possible pathogens. For questionable non-contaminant organisms, clinical significance was determined based on if patient was treated for the organism. For all bone marrow cultures, growth of the same organism within 1 month of the bone marrow specimen was surveyed to determine whether the organism would have been found by alternative methods. Results Of 483 bacterial bone marrow cultures, there were 110 (23%) positives, of which 76 (69%) were deemed contaminants. Twenty (18%) of the 76 contaminants grew in the routine bacterial culture. However, 49 (65%) contaminants grew in the AFB culture, of which 10 also grew in the bacterial culture. For the 34 non-contaminant organisms, 26 were determined to be clinically significant. Nineteen of the 26 had a matching culture (usually blood) growing the organism within 1 month. The majority of pathogens were mycobacteria (18 of the 34). Fungal organisms represented 5 cultures and 11 were bacterial. Of the 11 bacterial organisms, 1 was a Helicobacter species (grown in special media), and 4 had a matching positive blood culture. Only 4 (1% of 483) bacterial non-contaminants grew in the routine bacterial culture. Given an unknown number of true negatives, we can only conclude a positive predictive value (PPV) of 0.16 for routine bacterial cultures. Including AFB and fungal cultures, the PPV increased to 0.30. Conclusion Our findings indicate that routine bacterial bone marrow culture is unlikely to yield a novel result and is likely a poor use of lab resources. Disclosures All Authors: No reported disclosures
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Arris, Farrah Aida, Vincent Tiang Soon Thai, Wan Nabilah Manan i Mohd Shaiful Sajab. "A Revisit to the Formation and Mitigation of 3-Chloropropane-1,2-Diol in Palm Oil Production". Foods 9, nr 12 (29.11.2020): 1769. http://dx.doi.org/10.3390/foods9121769.
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Process-based contaminants in food—particularly in vegetable oils—have been a topic of interest due to their potential health risk on humans. Oral consumption above the tolerable daily intake might result in health risks. Therefore, it is critical to correctly address the food contaminant issues with a proper mitigation plan, in order to reduce and subsequently remove the occurrence of the contaminant. 3-monochloropropane-1,3-diol (3-MCPD), an organic chemical compound, is one of the heat- and process-induced food contaminants, belonging to a group called chloropropanols. This review paper discusses the occurrence of the 3-MCPD food contaminant in different types of vegetable oils, possible 3-MCPD formation routes, and also methods of reduction or removal of 3-MCPD in its free and bound esterified forms in vegetable oils, mostly in palm oil due to its highest 3-MCPD content.