Artículos de revistas sobre el tema "Contaminant transfers"
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Sterpenich, J., E. C. Gaucher, N. H. Schovsbo, J. G. Lerat, R. Mosser-Ruck y J. Pironon. "Geochemistry of Aquifer in Contact with Alum Shale: Evidence of Limited Contaminant Transfers". Procedia Earth and Planetary Science 17 (2017): 786–89. http://dx.doi.org/10.1016/j.proeps.2017.01.029.
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Rivoira, Luca, Michele Castiglioni, Nicola Nurra, Marco Battuello, Rocco Mussat Sartor, Livio Favaro y Maria Concetta Bruzzoniti. "Polycyclic Aromatic Hydrocarbons and Polychlorinated Biphenyls in Seawater, Sediment and Biota of Neritic Ecosystems: Occurrence and Partition Study in Southern Ligurian Sea". Applied Sciences 12, n.º 5 (1 de marzo de 2022): 2564. http://dx.doi.org/10.3390/app12052564.
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The Mediterranean Sea is subjected to a high anthropic pressure, which determines direct or indirect discharges of persistent organic pollutants deriving from intensive industrial activities. These compounds could easily enter and contaminate the whole marine compartment, with possible transfers (and contamination) among water, sediment and biota. Based on the above-mentioned assumptions, in this work we studied the presence of 16 polycyclic aromatic hydrocarbons (PAHs) and 14 dioxin and non-dioxin-like polychlorinated biphenyls (PCBs) in the neritic protected marine area of the Southern Ligurian Sea, affected by the impact of human activities. The study was focused on the possible partition of micropollutants within seawater, sediment and zooplankton. Results showed that both seasonal and anthropic causes strongly affect contaminant transfer behaviors, with summertime periods more impacted by PAH and PCB contamination. Regarding the PAH contamination, low molecular weight congeners were mainly detected in the target matrices, revealing concentrations up to 1 µg/L in seawater (anthracene), 250 µg/Kg in sediments (benzo[b]fluoranthene) and 2.3 mg/Kg in carnivorous copepods. Concerning PCBs, only few congeners were detected in the matrices studied. To better understand the occurrence of preferential bioaccumulation pathways in zooplankton, partition studies were also performed in several taxa (hyperbenthic Isopoda, holoplanktonic crustacean copepods and ichthyoplankton) through the calculation of BAF values, observing that both living and feeding habits could influence the bioaccumulation process.
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Younsi, Zohir, Lounes Koufi y Hassane Naji. "Numerical study of the effects of ventilated cavities outlet location on thermal comfort and air quality". International Journal of Numerical Methods for Heat & Fluid Flow 29, n.º 11 (4 de noviembre de 2019): 4462–83. http://dx.doi.org/10.1108/hff-09-2018-0518.
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Purpose A comprehensive investigation on the outlet air position effects on the thermal comfort and air quality has been achieved. In addition, airflow and temperature distributions in ventilated cavities filled with an air-CO2 mixture with mixed convection are predicted. The airflow enters from the cavity through an opening in the lower side of the left vertical wall and exits through the opening in one wall of the cavity. This paper aims to investigate the outlet location effect, four different placement configurations of output ports are considered. Three of them are placed on the upper side and the fourth on top of the opposite side of the inlet opening. A uniform heat and CO2 contaminant source are applied on the left vertical wall, while the remaining walls are impermeable and adiabatic to heat and solute. The cooling efficiency inside the enclosure and the average fluid temperature are computed for different Reynolds and Rayleigh numbers to find the most suitable fluid outlet position that ensures indoor comfortable conditions while effectively removing heat and the contaminant. This is demonstrated by three relevant indices, namely, the effectiveness for heat removal, the contaminant removal and the index of indoor air quality. Design/methodology/approach The simulations were performed via the finite-volume scSTREAM CFD solver V11. Three different values of CO2 amount are considered, namely, 103, 2 × 103 and 3 × 103 ppm, the Reynolds number being in the range 100 ≤ Re ≤ 800. Findings Based on the findings obtained, it is the configuration whose air outlet is placed near the heat source and the contaminant, which provides a better air distribution and a ventilation efficiency compared to the others ventilation strategies. Originality/value The studies on heat and mass transfers by natural and forced convection in ventilated cavities remain a fruitful research topic. Thereby, such a study deals with different ventilation strategies through cavities containing an air-CO2 mixture subjected to a mixed regime. In particular, the air inlet velocity and contaminant sources’ effects on thermal comfort and air quality have been investigated.
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Laceby, J. P., C. Chartin, O. Evrard, Y. Onda, L. Garcia-Sanchez y O. Cerdan. "Rainfall erosivity in subtropical catchments and implications for erosion and particle-bound contaminant transfer: a case-study of the Fukushima region". Hydrology and Earth System Sciences Discussions 12, n.º 7 (30 de julio de 2015): 7225–66. http://dx.doi.org/10.5194/hessd-12-7225-2015.
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Abstract. The Fukushima Dai-ichi nuclear power plant (FDNPP) accident in March 2011 resulted in a significant fallout of radiocesium over the Fukushima region. After reaching the soil surface, radiocesium is almost irreversibly bound to fine soil particles. Thereafter, rainfall and snow melt run-off events transfer particle-bound radiocesium downstream. Erosion models, such as the Universal Soil Loss Equation (USLE), depict a proportional relationship between rainfall and soil erosion. As radiocesium is tightly bound to fine soil and sediment particles, characterizing the rainfall regime of the fallout-impacted region is fundamental to modelling and predicting radiocesium migration. Accordingly, monthly and annual rainfall data from ~ 60 meteorological stations within a 100 km radius of the FDNPP were analysed. Monthly rainfall erosivity maps were developed for the Fukushima coastal catchments illustrating the spatial heterogeneity of rainfall erosivity in the region. The mean average rainfall in the Fukushima region was 1387 mm yr−1 (σ 230) with the mean rainfall erosivity being 2785 MJ mm ha−1 yr−1 (σ 1359). The results indicate that the majority of rainfall (60 %) and rainfall erosivity (86 %) occurs between June and October. During the year, rainfall erosivity evolves positively from northwest to southeast in the eastern part of the prefecture, whereas a positive gradient from north to south occurs in July and August, the most erosive months of the year. During the typhoon season, the coastal plain and eastern mountainous areas of the Fukushima prefecture, including a large part of the contamination plume, are most impacted by erosive events. Understanding these rainfall patterns, particularly their spatial and temporal variation, is fundamental to managing soil and particle-bound radiocesium transfers in the Fukushima region. Moreover, understanding the impact of typhoons is important for managing sediment transfers in subtropical regions impacted by cyclonic activity.
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Warmka, Anna, Erin L. Cortus, Kevin A. Janni, Abby Schuft y Sally Noll. "Opportunities and Methods for Using Fluorescent Gel as a Proxy for Pathogen Transfer in Biosecurity Research". Journal of Agricultural Safety and Health 29, n.º 1 (2023): 57–70. http://dx.doi.org/10.13031/jash.15253.
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Highlights While fluorescing gel may evaporate from a surface, luminance of the surface does not change. Fluorescing gel exhibits thresholds beyond which additional gel density does not increase luminance. Fluorescing gel only transfers between surfaces when it is wet. There are limits to relating luminance and mass transfer. Fluorescent material is a useful proxy for contamination transfer demonstration and research. Abstract. Glo Germ fluorescing material is a popular tool for teaching and researching contaminant transfer in and out of agriculture. The objectives of this paper were to: (1) quantify relationships between gel area density (mass per unit area) on a surface and its luminance, and (2) identify factors important in measuring Glo Germ gel transfer from one surface to another. Varying densities of Glo Germ gel were applied to paper, plastic, and rubber surfaces; each combination was replicated three times. Digital images collected over one hour were analyzed for luminance (the average gray value per unit area) under ultraviolet light. Changes in mass were also measured. For the gel transfer objective, a fixed weight was placed over varying wet and dried fluorescent material densities on paper and plastic surfaces. Gel masses were weighed, and images of the surface and receptor were taken before and after transfer. Evaporation was significantly faster (p = 0.0019) on the paper surface compared to the plastic surface. The luminance did not change as the gel evaporated from either surface. For each material, luminance initially increased with increasing density until a threshold, after which additional fluorescing gel density did not change luminance. The thresholds for paper, plastic, and rubber surfaces were 0.018, 0.014, and 0.041 g cm-2, respectively. Wet gel transfer test results suggest that transfer is easier to quantify on the receptor than the source. The dried gel did not exhibit measurable transfer. This research found limitations in equating mass transfer and luminance, but luminance threshold values can inform maximum Glo Germ application for imaging purposes. These research results support continued research and outreach with fluorescent material to reduce and prevent the spread of disease or other harmful contaminants in food and animal production. Keywords: Biosecurity, Fluorescence, Luminance, Mass transfer.
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Monaghan, R. M., L. C. Smith y R. W. Muirhead. "Pathways of contaminant transfers to water from an artificially-drained soil under intensive grazing by dairy cows". Agriculture, Ecosystems & Environment 220 (marzo de 2016): 76–88. http://dx.doi.org/10.1016/j.agee.2015.12.024.
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Perou, A. L. y J. M. Vergnaud. "Process of contaminant transfers during coextrusion of food packages made from recycled layer and virgin polymer layer". Plastics, Rubber and Composites 28, n.º 2 (febrero de 1999): 74–79. http://dx.doi.org/10.1179/146580199101540132.
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Tisseau, M. A., N. Fauchon, J. Cavard y T. Vandevelde. "Pesticide contamination of water resources: a case study - the rivers in the Paris region". Water Science and Technology 34, n.º 7-8 (1 de octubre de 1996): 147–52. http://dx.doi.org/10.2166/wst.1996.0614.
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For a number of years, the Compagnie Générale des Eaux has been studying pesticide contamination of surface water in order to better understand the origins and the main transfer mechanisms of these pollutants into water resources. Sampling campaigns are being carried out on the three main rivers of the Paris area to monitor a number of products from the triazine and urea families. This monitoring has confirmed the extension of agricultural non-point source pollution. The products being sought are present in the three rivers and, in most cases, in significant concentrations. Atrazine is the most important contaminant. Measured concentrations exceed the value of 100 ng/l most of the time, thus proving that the aquifers drained by the three rivers are contaminated. For a period of several months every year, concentrations approaching 1000 ng/l are observed in all the catchment areas being studied. These are the result of rapid transfers of atrazine in run-off water. This surface run-off transfer mode also seems to be applicable to the ureas found in surface water, especially during the periods when the products are used to treat crops. These works underline the complexity of agricultural non-point source pollution phenomena. They permit the identification of the predominant mechanisms operating in the transfer of the products. This is the first step towards setting up preventive measures and developing pollution forecasting tools.
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Tappin, A. D., P. J. Statham, J. D. Burton y S. Gellers-Barkmann. "Distributions and fluxes of contaminant metals in the North Sea: comparisons between field measurements and model simulations using NOSTRADAMUS". Environmental Chemistry 5, n.º 1 (2008): 51. http://dx.doi.org/10.1071/en07033.
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Environmental context. The North Sea, which is of significant ecological, economic and recreational value to NW Europe, has for many years received enhanced inputs of contaminant metals arising from human activity around its shores. Fluxes of copper, nickel, zinc, chromium and other constituents throughout the southern North Sea were estimated using a numerical model in order to identify the main sources and sinks for these metals. Comparison of model output with independent and other data showed good agreement in general. The results indicate that models of the kind developed here can be used to provide useful information on contaminant metal transport in coastal waters. Abstract. The steady-state 2-D vertically integrated numerical transport model NOSTRADAMUS has been used to simulate concentrations, distributions and fluxes of dissolved and particulate Cu, Cr, Ni and Zn in the southern North Sea between 51 and 56°N. The model results for the metals, and also for salinity and suspended sediments, were compared with field measurements from the Natural Environment Research Council (NERC) North Sea Project (NSP). The model generated realistic concentrations of all constituents, and in many cases reproduced the major features of the distributions, i.e. higher concentrations in the coastal zones and lower values in the central region. The sensitivity of the model results to variations in forcing data was extensively tested. In most cases, the default data provided the best results (quantified by residual sums of squares scores) despite no formal model calibration having been undertaken. Simulated fluxes indicated that metal inputs across the open sea boundaries were significant (Cu, 51%; Cr, 36%; Ni, 57%; Zn, 32%), although for Cu, Ni and Zn, river inputs were also important (13–15%). Metal transfers associated with particle settling and resuspension were significant (23–55%), and resuspended sediments were a minor net source, relative to particle settling, of Cu, Ni and Zn to the water column over the simulated year. In contrast, the resuspension of sediment from the seabed appeared to be a major source of Cr to the water column, a feature not explained at present. The major export from the North Sea in the model was through the northern boundary adjacent to the coast of Denmark. The fraction lost was in the range 61%, for Zn, to 90%, for Cr. Model results were compared with available independent data. The comparisons showed that the simulated constituent transfers approximated reasonably well with contemporary understanding of metal, and other constituent, fluxes in this region. These outcomes serve to emphasise the underlying capabilities of the model, and it can be concluded that NOSTRADAMUS provides the basis for heuristic studies of contaminant metals in the southern North Sea.
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Monaghan, RM, DJ Houlbrooke y LC Smith. "The use of low-rate sprinkler application systems for applying farm dairy effluent to land to reduce contaminant transfers". New Zealand Journal of Agricultural Research 53, n.º 4 (18 de noviembre de 2010): 389–402. http://dx.doi.org/10.1080/00288233.2010.505943.
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Laceby, J. Patrick, Caroline Chartin, Olivier Evrard, Yuichi Onda, Laurent Garcia-Sanchez y Olivier Cerdan. "Rainfall erosivity in catchments contaminated with fallout from the Fukushima Daiichi nuclear power plant accident". Hydrology and Earth System Sciences 20, n.º 6 (23 de junio de 2016): 2467–82. http://dx.doi.org/10.5194/hess-20-2467-2016.
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Abstract. The Fukushima Daiichi nuclear power plant (FDNPP) accident in March 2011 resulted in the fallout of significant quantities of radiocesium over the Fukushima region. After reaching the soil surface, radiocesium is quickly bound to fine soil particles. Thereafter, rainfall and snowmelt run-off events transfer particle-bound radiocesium downstream. Characterizing the precipitation regime of the fallout-impacted region is thus important for understanding post-deposition radiocesium dynamics. Accordingly, 10 min (1995–2015) and daily precipitation data (1977–2015) from 42 meteorological stations within a 100 km radius of the FDNPP were analyzed. Monthly rainfall erosivity maps were developed to depict the spatial heterogeneity of rainfall erosivity for catchments entirely contained within this radius. The mean average precipitation in the region surrounding the FDNPP is 1420 mm yr−1 (SD 235) with a mean rainfall erosivity of 3696 MJ mm ha−1 h−1 yr−1 (SD 1327). Tropical cyclones contribute 22 % of the precipitation (422 mm yr−1) and 40 % of the rainfall erosivity (1462 MJ mm ha−1 h−1 yr−1 (SD 637)). The majority of precipitation (60 %) and rainfall erosivity (82 %) occurs between June and October. At a regional scale, rainfall erosivity increases from the north to the south during July and August, the most erosive months. For the remainder of the year, this gradient occurs mostly from northwest to southeast. Relief features strongly influence the spatial distribution of rainfall erosivity at a smaller scale, with the coastal plains and coastal mountain range having greater rainfall erosivity than the inland Abukuma River valley. Understanding these patterns, particularly their spatial and temporal (both inter- and intraannual) variation, is important for contextualizing soil and particle-bound radiocesium transfers in the Fukushima region. Moreover, understanding the impact of tropical cyclones will be important for managing sediment and sediment-bound contaminant transfers in regions impacted by these events.
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Coxon, Catherine y David Drew. "Interdependence of groundwater and surface water in lowland karst areas of western Ireland: management issues arising from water and contaminant transfers". Geological Society, London, Special Publications 182, n.º 1 (2000): 81–88. http://dx.doi.org/10.1144/gsl.sp.2000.182.01.08.
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Newby, D. T., T. J. Gentry y I. L. Pepper. "Comparison of 2,4-Dichlorophenoxyacetic Acid Degradation and Plasmid Transfer in Soil Resulting from Bioaugmentation with Two Different pJP4 Donors". Applied and Environmental Microbiology 66, n.º 8 (1 de agosto de 2000): 3399–407. http://dx.doi.org/10.1128/aem.66.8.3399-3407.2000.
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ABSTRACT A pilot field study was conducted to assess the impact of bioaugmentation with two plasmid pJP4-bearing microorganisms: the natural host, Ralstonia eutropha JMP134, and a laboratory-generated strain amenable to donor counterselection,Escherichia coli D11. The R. eutropha strain contained chromosomal genes necessary for mineralization of 2,4-dichlorophenoxyacetic acid (2,4-D), while the E. colistrain did not. The soil system was contaminated with 2,4-D alone or was cocontaminated with 2,4-D and Cd. Plasmid transfer to indigenous populations, plasmid persistence in soil, and degradation of 2,4-D were monitored over a 63-day period in the bioreactors. To assess the impact of contaminant reexposure, aliquots of bioreactor soil were reamended with additional 2,4-D. Both introduced donors remained culturable and transferred plasmid pJP4 to indigenous recipients, although to different extents. Isolated transconjugants were members of theBurkholderia and Ralstonia genera, suggesting multiple, if not successive, plasmid transfers. Upon a second exposure to 2,4-D, enhanced degradation was observed for all treatments, suggesting microbial adaptation to 2,4-D. Upon reexposure, degradation was most rapid for the E. coli D11-inoculated treatments. Cd did not significantly impact 2,4-D degradation or transconjugant formation. This study demonstrated that the choice of donor microorganism might be a key factor to consider for bioaugmentation efforts. In addition, the establishment of an array of stable indigenous plasmid hosts at sites with potential for reexposure or long-term contamination may be particularly useful.
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Grosser, Robert J., Michael Friedrich, David M. Ward y William P. Inskeep. "Effect of Model Sorptive Phases on Phenanthrene Biodegradation: Different Enrichment Conditions Influence Bioavailability and Selection of Phenanthrene-Degrading Isolates". Applied and Environmental Microbiology 66, n.º 7 (1 de julio de 2000): 2695–702. http://dx.doi.org/10.1128/aem.66.7.2695-2702.2000.
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ABSTRACT The sorption of organic contaminants by natural organic matter (NOM) often limits substrate bioavailability and is an important factor affecting microbial degradation rates in soils and sediments. We hypothesized that reduced substrate bioavailability might influence which microbial assemblages are responsible for contaminant degradation under enrichment culture conditions. Our primary goal was to characterize enrichments in which different model organic solid phases were used to establish a range of phenanthrene bioavailabilities for soil microorganisms. Phenanthrene sorption coefficients (expressed as log KD values) ranged from 3.0 liters kg−1 for Amberlite carboxylic acid cation-exchange resin (AMB) to 3.5 liters kg−1 for Biobeads polyacrylic resin (SM7) and 4.2 liters kg−1 for Biobeads divinyl benzene resin (SM2). Enrichment cultures were established for control (no sorptive phase), sand, AMB, SM7, and SM2 treatments by using two contaminated soils (from Dover, Ohio, and Libby, Mont.) as the initial inocula. The effects of sorption by model phases on the degradation of phenanthrene were evaluated for numerous transfers in order to obtain stable microbial assemblages representative of sorptive and nonsorptive enrichment cultures and to eliminate the effects of the NOM present in the initial inoculum. Phenanthrene degradation rates were similar for each soil inoculum and ranged from 4 to 5 μmol day−1 for control and sand treatments to approximately 0.4 μmol day−1 in the presence of the SM7 sorptive phase. The rates of phenanthrene degradation in the highly sorptive SM2 enrichment culture were insignificant; consequently, stable microbial populations could not be obtained. Bacterial isolates obtained from serial dilutions of enrichment culture samples exhibited significant differences in rates of phenanthrene degradation performed in the presence of SM7, suggesting that enrichments performed in the presence of a sorptive phase selected for different microbial assemblages than control treatments containing solid phase phenanthrene.
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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, n.º 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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Gatel, Laura, Claire Lauvernet, Nadia Carluer, Sylvain Weill y Claudio Paniconi. "Sobol Global Sensitivity Analysis of a Coupled Surface/Subsurface Water Flow and Reactive Solute Transfer Model on a Real Hillslope". Water 12, n.º 1 (30 de diciembre de 2019): 121. http://dx.doi.org/10.3390/w12010121.
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The migration and fate of pesticides in natural environments is highly complex. At the hillslope scale, the quantification of contaminant fluxes and concentrations requires a physically based model. This class of model has recently been extended to include coupling between the surface and the subsurface domains for both the water flow and solute transport regimes. Due to their novelty, the relative importance of and interactions between the main model parameters has not yet been fully investigated. In this study, a global Sobol sensitivity analysis is performed on a vineyard hillslope for a one hour intensive rain event with the CATHY (CATchment HYdrology) integrated surface/subsurface model. The event-based simulation involves runoff generation, infiltration, surface and subsurface solute transfers, and shallow groundwater flow. The results highlight the importance of the saturated hydraulic conductivity K s and the retention curve shape parameter n and they reveal a strong role for parameter interactions associated with the exchange processes represented in the model. The mass conservation errors generated by the model are lower than 1% in 99.7% of the simulations. Boostrapping analysis of sampling methods and errors associated with the Sobol indices highlights the relevance of choosing a large sampling size (at least N = 1000) and raises issues associated with rare but extreme output results.
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Mangas-Suarez, Mario, Efren Garcia-Ordiales, Julio Antonio Pérez, Rodrigo Álvarez, Alberto Villa, Almudena Ordoñez y Nieves Roqueñí. "Enrichment of Metals in the Sediments of an Industrially Impacted Estuary: Geochemistry, Dispersion and Environmental Considerations". Applied Sciences 12, n.º 21 (30 de octubre de 2022): 10998. http://dx.doi.org/10.3390/app122110998.
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The city of Avilés is one of the most industrialized cities in the north of Spain and, accordingly, its estuary and coastal area have been subjected to great anthropic impacts in the last 100 years. This research attempts to establish a preliminary scenario of the geochemical and environmental status of both coastal and estuarine sediments in this area. For this study, a total of 96 sediment samples were collected, processed and analyzed to quantify the granulometric distribution of the sediments, as well as their concentrations of organic carbon and main metal(oids) that may cause an environmental risk. The results show that the estuarine sediments present important concentrations of Cd, Hg, Pb and Zn that allow them to be clearly differentiated from the coastal sediments; this information, along with the sedimentology, implies that the estuary acts as a sink of pollution and not as source to the coastal area. Inside the estuary, the high levels of contamination produce a significant potential ecological risk due to contaminant transfers to other environmental compartments and to the biota. Although direct discharges of industrial effluents have been gradually eliminated, the current state of the sediment requires the implementation of measures that are more consistent than natural regeneration in order to ensure low risk levels for the ecosystem.
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Krahn, MM, D. G. Burrows, J. E. Stein, P. R. Becker, M. M. Schantz, D. C. G. Muir, T. M. O'Hara y T. Rowles. "White whales (Delphinapterus leucas) from three Alaskan stocks: Concentrations and patterns of persistent organochlorine contaminants in blubber". J. Cetacean Res. Manage. 1, n.º 3 (1 de diciembre de 1999): 239–50. http://dx.doi.org/10.47536/jcrm.v1i3.471.
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White whale (De!phinapterus leucas) blubber samples from three of the five different Alaskan stocks, Cook Inlet (n = 20), Eastern Chukchi Sea (n = 19) and Eastern Beaufort Sea (n = 2), were analysed for levels and patterns of chemical contaminants. Blubber from these whales contained LPCBs, LDDTs, Lchlordanes, HCB, dieldrin, mirex, Ltoxaphene and LHCH, generally in concentration ranges similar to those found in white whales from the Canadian Arctic but lower than those in white whales from the highly contaminated St Lawrence River. Males from the Cook Inlet and Eastern Chukchi Sea stocks had higher mean concentrations of all contaminant groups than females of the same stock, a result attributable to the transfer of these organochlorine contaminants (OCs) from the mother to the calf during pregnancy and lactation. Principal component analysis of patterns of contaminants present in blubber showed that the Cook Inlet stock appeared to have identifiable contaminant patterns that allowed the stock to be distinguished from the others. Our results also showed that blubber from the three Alaskan stocks was a source of contaminant exposure for human subsistence consumers, but the health risks from consumption are currently unknown.
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Veloz Martínez, Irvin, Jackeline Iturbe Ek, Ethan C. Ahn y Alan O. Sustaita. "Molecularly imprinted polymers via reversible addition–fragmentation chain-transfer synthesis in sensing and environmental applications". RSC Advances 12, n.º 15 (2022): 9186–201. http://dx.doi.org/10.1039/d2ra00232a.
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Environmental contaminants constitute an ecological and health hazard, which requires green sensing. The RAFT-MIP approach for tailor-made selective receptors enhances them via binding affinities for use in environmental contaminant sensors.
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Nor Azirah Mohd Fohimi, Koay Mei Hyie, Salina Budin, Normariah Che Maideen, Nazri Kamsah y Haslinda Mohamed Kamar. "An Experimental Study of Indoor Air Pollution in New Office Building". Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 94, n.º 1 (19 de abril de 2022): 120–28. http://dx.doi.org/10.37934/arfmts.94.1.120128.
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Air pollution is a major environmental risk to health. The new building normally has a facing problem with indoor air pollutant. New construction materials and furniture will contribute higher contaminants compared to old materials. The effect of indoor air pollutants can result in human health problems, discomfort and reduces their productivity. The purpose of this present work is to experimental study the indoor air pollution status regarding carbon dioxide, carbon monoxide, volatile organic compounds, and formaldehyde concentration in an administration office at the new building faculty of mechanical engineering in Johor Bahru, Malaysia. The contaminants concentration values are investigated through field measurements and then compared to the limits stated in the Occupational Safety and Health Act standard. The field measurement of contaminant concentration level was conducted at the intersect plane between the vertical plane at the center of the air conditioning diffuser and the horizontal plane at 1.2 m from the floor. The contaminant concentration readings were taken at 6 locations inside the office. The data were conducted during actual working conditions. The reading of contaminants concentration is taken in 30 minutes. One minute is equal to one number of samples. It was found that only the formaldehyde concentration is exceeding the maximum limit.
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Gao, Yanan, Peng Guo, Zetian Zhang, Minghui Li y Feng Gao. "Migration of the Industrial Wastewater in Fractured Rock Masses Based on the Thermal-Hydraulic-Mechanical Coupled Model". Geofluids 2021 (16 de octubre de 2021): 1–13. http://dx.doi.org/10.1155/2021/5473719.
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Industrial wastewater may have a long-time effect on the environment and human life as it goes underground and causes serious pollution continuously. To have a well understanding of the migration of such wastewater is a basic task for industrial wastewater treatment as well as industrial design. To study the migration mechanism of industrial wastewater in rock formations, the governing equations such as mechanics, seepage, heat, and mass transfer are reviewed, referenced, and proposed. The thermal (T)-hydraulic (H)-mechanical (M) coupled model of the multimedia of matrix-fault and matrix-fracture-fault is established. The influence of the fault and the fractures on the pressure distribution and contaminant migration is analyzed. The influence of fault length, width, dip angle, permeability, and temperature of wastewater on contaminant migration is parametrically studied. The following results can be obtained. (1) The fracture quantitively affects the concentration distribution, while the fault dominates the concentration distribution and contaminant migration. (2) The migration of the contaminants can be geometrically divided into 3 zones along the direction of the fault: the saturation zone, the rapid diffusion zone, and the concentration decrease zone. (3) There is a peak of the concentration along the bottom of the model. The position of the peak is the projection of the endpoint of the fault. (4) The fault length has the most significant effect on contaminant accumulation. The temperature of the wastewater has the minimum effect on the contaminant accumulation. (5) The accumulation of concentrations can be divided into 2 stages, the slow growth stage (before 20 years) and the rapid growth stage (after 20 years). The main channel of contaminant migration in the slow growth stage is a fault. During the rapid growth stage, the contaminants penetrate through the rock matrix as well as the fault.
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Tatsukawa, R. "Contamination of Chlorinated Organic Substances in the Ocean Ecosystem". Water Science and Technology 25, n.º 11 (1 de junio de 1992): 1–8. http://dx.doi.org/10.2166/wst.1992.0266.
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Persistent organochlorines such as PCBs, DDTs and HCHs are ubiquitous contaminants found in seas and oceans worldwide. They are transferred from terrestrial contaminant sources to open ocean through atmosphere and ultimately deposit into the oceanic waters. The tropical regions are likely to contribute greatly to the global contamination of some organochlorines in recent years. The contaminants in water phase are taken into ecosystems following the prey-predator relationship in the food-chain. In this context, cetaceans like dolphins, porpoises and whales are recognized as one of the animal groups most at risk from persistent organochlorines in the environment. They accumulate extremely high concentrations of organochlorines through feeding, and transfer large quantities to offspring during lactation. Unfortunately, they have a small capacity to degrade these contaminants. It may be concluded that marine mammals, particularly cetaceans, are among the most vulnerable organisms to long-term toxicity of hazardous man-made chenicals.
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Meyer, A. M., N. Meijer, E. F. Hoek-van den Hil y H. J. van der Fels-Klerx. "Chemical food safety hazards of insects reared for food and feed". Journal of Insects as Food and Feed 7, n.º 5 (13 de agosto de 2021): 823–31. http://dx.doi.org/10.3920/jiff2020.0085.
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Insects are a promising future source of sustainable proteins within a circular economy. Proving the safety of insects for food and feed is necessary prior to supplying them to the market. This literature review provides a state-of-the-art overview of the chemical food safety hazards for insects reared for food and feed, focusing mainly on transfer of contaminants from the substrate. Contaminants covered are: heavy metals, dioxins and polychlorinated biphenyls, polyaromatic hydrocarbons, pesticides, veterinary drugs, mycotoxins, and plant toxins. The twelve insect species reported as having the largest potential as feed and food in the EU are included. Transfer and bioaccumulation of contaminants depend on the chemical, insect species, life stage, and source of contaminant (spiked vs natural), as well as the particular substrate and rearing conditions. The heavy metals lead, arsenic, mercury, and cadmium can accumulate, whereas mycotoxins and polycyclic aromatic hydrocarbons (PAHs) seem not to accumulate. Mycotoxins and veterinary drugs could be degraded by insects; their metabolic routes need to be further investigated. Data are generally limited, but in particular for PAHs, plant toxins, and dioxins and dioxin-like polychlorinated biphenyls. Further research on chemical safety of different edible insects is therefore warranted.
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Yang, Chun-Bai-Xue, Shi-Jin Feng y Qi-Teng Zheng. "Influence of extraction and injection conditions on the performance of thermal-enhanced soil vapor extraction". IOP Conference Series: Earth and Environmental Science 1335, n.º 1 (1 de mayo de 2024): 012026. http://dx.doi.org/10.1088/1755-1315/1335/1/012026.
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Abstract Thermal-enhanced soil vapor extraction (T-SVE) is an in-situ remedial technique that can address the limitations of contaminant mass transfer and soil permeability. The relative humidity of the injected air, heating temperature of the thermal well, extraction pressure, and extraction mode are important design parameters of a T-SVE system that determine the temporal and spatial distributions of soil temperature and removal rate. Using a thermal–hydraulic–chemical coupled model with the interphase mass transfer of contaminants and water evaporation/condensation, this study investigated the effects of relative humidity, heating temperature, extraction pressure, and extraction mode on T-SVE performance. The results showed that with an increase in relative humidity, the heating temperature of the contaminated soil significantly improved; however, the removal rate of contaminants decreased, particularly in the late stage of remediation. Considering the heating temperature of the thermal well, a critical air relative humidity value that significantly affects the removal rate of contaminants was observed. The heating temperature of the thermal well must be considered in engineering design; however, the evaluation of the relative humidity of the air cannot be ignored.
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Saadun, Mohd Noor Asril, C. S. Nor Azwadi, M. N. Hazwani, Mohamad Shukri Zakaria, Muhammad Zaidan Abdul Manaf y Mohd Hafidzal Mohd Hanafi. "Numerical Analysis on the Effects of Cavity Geometry with Heat towards Contaminant Removal". Applied Mechanics and Materials 393 (septiembre de 2013): 851–56. http://dx.doi.org/10.4028/www.scientific.net/amm.393.851.
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Contaminants are recently discovered at the joint of large piping system and causing defect to industrial product. A computational analysis can be used as a solution of the hydrodynamic contaminant removal without any modification needed. In this paper, the effect of heat is introduced to analyze the heat transfer and flow field in a channel with cavity heated at the bottom sides coupled with different shape of cavity. The cavity shape used comes with three shapes i.e. square, triangle and semicircle. The process of fluid dynamic in a cavity is modeled via numerical solution of the NavierStokes equations using Cubic Interpolated Profile (CIP) method. By using the simulation of hydrodynamic contaminant removal, the flow of streamlines and vortices pattern was investigated in the cavities. In order to remove all of the contaminant, hydrodynamic need to take part in this simulation which is flow from the inlet of the channel and create vortices to remove it from the cavities. The result shows that the percentage of contaminant removal is higher for semicircle cavity with higher Grashof number. The result also indicates that vortices formation is highly dependent on the cavity geometry and creates a buoyancy effect.
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Davranche, Melanie, Alexandre Gélabert y Marc F. Benedetti. "Electron Transfer Drives Metal Cycling in the Critical Zone". Elements 16, n.º 3 (1 de junio de 2020): 185–90. http://dx.doi.org/10.2138/gselements.16.3.185.
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Electron transfer in the critical zone is driven by biotic and abiotic mechanisms and controls the fate of inorganic and organic contaminants, whether redox-sensitive or not. In these environments, Fe- and Mn-bearing minerals, as well as organic matter, are key compounds. They interact with each other and constitute important electron shuttles. As a result, not only their solubility but also their structure controls the mobility of many essential and toxic elements. In addition, microorganisms that form hot spots and are widespread in environmental systems are also primordial players in electron transfer processes by acting as a catalyst between an electron donor and an acceptor, and through their contaminant detoxification metabolism.
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Texier, Jérôme, Julio Gonçalvès y Agnès Rivière. "Numerical Assessment of Groundwater Flowpaths below a Streambed in Alluvial Plains Impacted by a Pumping Field". Water 14, n.º 7 (30 de marzo de 2022): 1100. http://dx.doi.org/10.3390/w14071100.
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The quality of the water from a riverbank well field is the result of the mixing ratios between the surface water and the local and regional groundwater. The mixing ratio is controlled by the complex processes involved in the surface water–groundwater interactions. In addition, the drawdown of the groundwater level greatly determines the water head differences between the river water and groundwater, as well as the field flowpath inside the alluvial plain, which subsequently impacts the water origin in the well. In common view, groundwater flows from both sides of the valley towards the river, and the groundwater divide is located at the middle of the river. Here, we studied the standard case of a river connected with an alluvial aquifer exploited by a linear pumping field on one riverbank, and we proposed to determine the physical parameters controlling the occurrence of groundwater flow below the river from one bank to the other (cross-riverbank flow). For this purpose, a 2D saturated–unsaturated flow numerical model is used to analyze the groundwater flowpath below a streambed. The alternative scenarios of surface water–groundwater interactions considered here are based on variable regional gradient conditions, pumping conditions, streambed clogging and the aquifer thickness to the river width ratio (aspect ratio). Parameters such as the aspect ratio and the properties of the clogging layer play a crucial role in the occurrence of this flow, and its magnitude increases with the aquifer thickness and the streambed clogging. We demonstrate that for an aspect ratio below 0.2, cross-riverbank flow is negligible. Conversely, when the aspect ratio exceeds 0.7, 20% of the well water comes from the other bank and can even exceed the river contribution when the aspect ratio reaches 0.95. In this situation, contaminant transfers from the opposite riverbank should not be neglected even at low clogging.
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Ackerley, D. F., C. F. Gonzalez, C. H. Park, R. Blake, M. Keyhan y A. Matin. "Chromate-Reducing Properties of Soluble Flavoproteins from Pseudomonas putida and Escherichia coli". Applied and Environmental Microbiology 70, n.º 2 (febrero de 2004): 873–82. http://dx.doi.org/10.1128/aem.70.2.873-882.2004.
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ABSTRACT Cr(VI) (chromate) is a toxic, soluble environmental contaminant. Bacteria can reduce chromate to the insoluble and less toxic Cr(III), and thus chromate bioremediation is of interest. Genetic and protein engineering of suitable enzymes can improve bacterial bioremediation. Many bacterial enzymes catalyze one-electron reduction of chromate, generating Cr(V), which redox cycles, generating excessive reactive oxygen species (ROS). Such enzymes are not appropriate for bioremediation, as they harm the bacteria and their primary end product is not Cr(III). In this work, the chromate reductase activities of two electrophoretically pure soluble bacterial flavoproteins—ChrR (from Pseudomonas putida) and YieF (from Escherichia coli)—were examined. Both are dimers and reduce chromate efficiently to Cr(III) (k cat/Km = ∼2 × 104 M−1 · s−1). The ChrR dimer generated a flavin semiquinone during chromate reduction and transferred >25% of the NADH electrons to ROS. However, the semiquinone was formed transiently and ROS diminished with time. Thus, ChrR probably generates Cr(V), but only transiently. Studies with mutants showed that ChrR protects against chromate toxicity; this is possibly because it preempts chromate reduction by the cellular one-electron reducers, thereby minimizing ROS generation. ChrR is thus a suitable enzyme for further studies. During chromate reduction by YieF, no flavin semiquinone was generated and only 25% of the NADH electrons were transferred to ROS. The YieF dimer may therefore be an obligatory four-electron chromate reducer which in one step transfers three electrons to chromate and one to molecular oxygen. As a mutant lacking this enzyme could not be obtained, the role of YieF in chromate protection could not be directly explored. The results nevertheless suggest that YieF may be an even more suitable candidate for further studies than ChrR.
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FENTON, O., M. G. HEALY, F. BRENNAN, M. M. R. JAHANGIR, G. J. LANIGAN, K. G. RICHARDS, S. F. THORNTON y T. G. IBRAHIM. "Permeable reactive interceptors: blocking diffuse nutrient and greenhouse gases losses in key areas of the farming landscape". Journal of Agricultural Science 152, S1 (29 de enero de 2014): 71–81. http://dx.doi.org/10.1017/s0021859613000944.
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SUMMARYEngineered remediation technologies such as denitrifying bioreactors target single contaminants along a nutrient transfer continuum. However, mixed contaminant discharges to a water body are more common from agricultural systems. Indeed, evidence presented herein indicates that pollution swapping within denitrifying bioreactor systems adds to such deleterious discharges. The present paper proposes a more holistic approach to contaminant remediation on farms, moving from the use of ‘denitrifying bioreactors’ to the concept of a ‘permeable reactive interceptor’ (PRI). Besides management changes, a PRI should contain additional remediation cells for specific contaminants in the form of solutes, particles or gases. Balance equations and case studies representing different geographic areas are presented and used to create weighting factors. Results showed that national legislation with respect to water and gaseous emissions will inform the eventual PRI design. As it will be expensive to monitor a system continuously in a holistic manner, it is suggested that developments in the field of molecular microbial ecology are essential to provide further insight in terms of element dynamics and the environmental controls on biotransformation and retention processes within PRIs. In turn, microbial and molecular fingerprinting could be used as an in-situ cost-effective tool to assess nutrient and gas balances during the operational phases of a PRI.
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Haas, Bettina S. y Reimer Herrmann. "Transport of chlorinated hydrocarbons between sewage and sewer atmosphere". Water Science and Technology 34, n.º 3-4 (1 de agosto de 1996): 557–64. http://dx.doi.org/10.2166/wst.1996.0476.
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Sewage containing volatile contaminants is a potential VOC-source in cities. Thus we tried to evaluate volatilization out of the sewerage system by measurements of contaminants in sewer gas and sewage. Our results from a medium sized town with little industry showed that sewer gas is mainly contaminated with alkanes, small aromatic compounds and chlorinated hydrocarbons. For three chlorinated hydrocarbons (chloroform, trichloroethene, tetrachloroethene) we determined mass transfer coefficients out of sewage and used these data to estimate mass fluxes from sewage and emissions out of the sewerage system for two sewer stretches. Considerable emission of chlorinated hydrocarbons from sewage, i.e. fluxes of some 10 to 100 g per m2·d, occurred only when the contaminant input via sewage was between some g and mg per litre for a single compound. For concentrations that were about 3 orders of magnitude less, emissions were negligible.
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RICARD, MICHELLE, GILLES DORRIS, SYLVAIN GENDRON, NATALIE PAGÉ, DENISE FILION y CARLOS CASTRO. "A new online image analyzer for macrocontaminants in recycled pulps". February 2012 11, n.º 2 (1 de marzo de 2012): 19–28. http://dx.doi.org/10.32964/tj11.2.19.
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A new image analysis-based instrument has been developed for measurement of low density and high density macrocontaminants from recycled pulp or whitewater. The unit is coupled to a pulp classifier that isolates the contaminants from pulp and concentrates them before their transfer to a specialized chamber that further separates the contaminants based on their relative density to water. The low density contaminants float on the water surface, whereas the high density macrocontaminants sink onto the settling plate, where images of both contaminant types are then captured and analysed. Through image analysis, the high density contaminants are further classified into two categories: contaminants that are whitish in color and mainly comprised of stickies are named heavy stickies, whereas contaminants that are blackish in color and comprised of black toners and dark wood components are named dirt. When operating in the online mode with autosamplers delivering the samples to the pulp classifier, the instrument provides macrocontaminant determinations every 15 min. The total count and surface area of both types of macrocontaminants per kilograms of pulp can then be sent by direct link to the mill data control system, allowing an effective follow-up of macrocontaminant changes in process pulps and waters. The unit also allows the user to view images of the contaminants. The analyzer results obtained in terms of number and area of macrocontaminants show a linear relationship with TAPPI T-277 om-07 “Macro stickies content in pulp: the ‘pick-up’ method.”
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Wolkers, Hans, Peter J. Corkeron, Sofie M. Van Parijs, Tiu Similä y Bert van Bavel. "ACCUMULATION AND TRANSFER OF CONTAMINANTS IN KILLER WHALES (ORCINUS ORCA) FROM NORWAY: INDICATIONS FOR CONTAMINANT METABOLISM". Environmental Toxicology and Chemistry 26, n.º 8 (2007): 1582. http://dx.doi.org/10.1897/06-455r1.1.
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Rech, Aline, Elisa Pacheco, Jakcemara Caprario, Julio Cesar Rech y Alexandra Rodrigues Finotti. "Low-Impact Development (LID) in Coastal Watersheds: Infiltration Swale Pollutant Transfer in Transitional Tropical/Subtropical Climates". Water 14, n.º 2 (14 de enero de 2022): 238. http://dx.doi.org/10.3390/w14020238.
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The control of runoff pollution is one of the advantages of low-impact development (LID) or sustainable drainage systems (SUDs), such as infiltration swales. Coastal areas may have characteristics that make the implementation of drainage systems difficult, such as sandy soils, shallow aquifers and flat terrains. The presence of contaminants was investigated through sampling and analysis of runoff, soil, and groundwater from a coastal region served by an infiltration swale located in southern Brazil. The swale proved to be very efficient in controlling the site’s urban drainage volumes even under intense tropical rainfall. Contaminants of Cd, Cu, Pb, Zn, Cr, Fe, Mn and Ni were identified at concentrations above the Brazilian regulatory limit (BRL) in both runoff and groundwater. Soil concentrations were low and within the regulatory limits, except for Cd. The soil was predominantly sandy, with neutral pH and low ionic exchange capacity, characteristic of coastal regions and not very suitable for contaminant retention. Thus, this kind of structure requires improvements for its use in similar environments, such as the use of adsorbents in soil swale to increase its retention capacity.
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Obeidy, Ahmed y M. A. L. Smith. "ESTABLISHING CULTURES FROM MATURE PECAN EMBRYO EXPLANTS ON MEDIA WITH LOW WATER AVAILABILITY". HortScience 25, n.º 9 (septiembre de 1990): 1149F—1149. http://dx.doi.org/10.21273/hortsci.25.9.1149.
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Endophytic fungi associated with mature pecan nuts (cultivars `Smart', `Desirable' and `Owens') prevented successful, contaminant-free. in vitro culture of embryo explants, even after rigorous surface disinfestation of the nuts and careful aseptic shelling. Disinfestation with sodium hypochlorite after removing the shells was also unsuccessful, because even dilute concentrations which were ineffective against the fungal contaminants destroyed embryo viability. An alternative disinfestation technique is required to establish in vitro cultures from mature pecan explants. Explanting media with low water availability were developed to capitalize on the relatively stringent requirement of most fungal contaminants for free water. The explanting media were supplemented with 0.9-1.5% agar. Other media components were selectively included or omitted to test their influence on water activity and fungal growth. After four weeks of culture, the incidence of contamination was reduced to 30% or less on modified explanting media, compared to 100% loss to contamination on control medium (0.5% agar). The brief initial culture period effectively eliminated fungal contamination from cultures by plasmolyzing fungal hyphae or denaturing fungal protein, without effecting pecan embryo viability. Cultures remained contaminant-free after transfer to control medium. Axillary and adventitious bud development from disinfested embryo axes was subsequently induced in a medium with 18 μM BAP and 5 μM IBA, and regeneration from cotyledon explants was accomplished in a medium with 50 μM NAA. This disinfestation technique allows mature pecan embryo explants to be used in biotechnology.
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Obeidy, Ahmed y M. A. L. Smith. "ESTABLISHING CULTURES FROM MATURE PECAN EMBRYO EXPLANTS ON MEDIA WITH LOW WATER AVAILABILITY". HortScience 25, n.º 9 (septiembre de 1990): 1149f—1149. http://dx.doi.org/10.21273/hortsci.25.9.1149f.
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Endophytic fungi associated with mature pecan nuts (cultivars `Smart', `Desirable' and `Owens') prevented successful, contaminant-free. in vitro culture of embryo explants, even after rigorous surface disinfestation of the nuts and careful aseptic shelling. Disinfestation with sodium hypochlorite after removing the shells was also unsuccessful, because even dilute concentrations which were ineffective against the fungal contaminants destroyed embryo viability. An alternative disinfestation technique is required to establish in vitro cultures from mature pecan explants. Explanting media with low water availability were developed to capitalize on the relatively stringent requirement of most fungal contaminants for free water. The explanting media were supplemented with 0.9-1.5% agar. Other media components were selectively included or omitted to test their influence on water activity and fungal growth. After four weeks of culture, the incidence of contamination was reduced to 30% or less on modified explanting media, compared to 100% loss to contamination on control medium (0.5% agar). The brief initial culture period effectively eliminated fungal contamination from cultures by plasmolyzing fungal hyphae or denaturing fungal protein, without effecting pecan embryo viability. Cultures remained contaminant-free after transfer to control medium. Axillary and adventitious bud development from disinfested embryo axes was subsequently induced in a medium with 18 μM BAP and 5 μM IBA, and regeneration from cotyledon explants was accomplished in a medium with 50 μM NAA. This disinfestation technique allows mature pecan embryo explants to be used in biotechnology.
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Moreira, Juliana Botelho, Thaisa Duarte Santos, Munise Zaparoli, Ana Claudia Araujo de Almeida, Jorge Alberto Vieira Costa y Michele Greque de Morais. "An Overview of Nanofiltration and Nanoadsorption Technologies to Emerging Pollutants Treatment". Applied Sciences 12, n.º 16 (21 de agosto de 2022): 8352. http://dx.doi.org/10.3390/app12168352.
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The presence of emerging contaminants in water resources has been a global concern due to their environmental impact and effects on human and animal health. These compounds include pharmaceuticals and personal care products, pesticides, fire retardants, hormones, and plasticizers, among others. These contaminants are not completely removed during water and wastewater conventional treatment. Thus, alternative processes are necessary to face this issue. In this context, nanotechnology represents a promising strategy for the remediation of emerging contaminants. Nanostructured materials have highlighted properties, such as adsorption capacity and porosity, chemical stability, reactivity, mobility, and antimicrobial activity. The diversity of nanomaterials and the possibility of combining them contribute to their application in contaminant mitigation. Furthermore, they can be used in different removal techniques such as adsorption, and membrane filtration. Thus, this review article provides an overview and advances in the production and application of nanofiltration membranes and adsorbent nanomaterials for the treatment of effluents containing emerging pollutants.
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Krahn, Margaret M., Gina M. Ylitalo, Douglas G. Burrows, John Calambokidis, Sue E. Moore, Merrill Gosho, Patrick Gearin et al. "Organochlorine contaminant concentrations and lipid profiles in eastern North Pacific gray whales (Eschrichtius robustus)". J. Cetacean Res. Manage. 3, n.º 1 (25 de mayo de 2023): 19–29. http://dx.doi.org/10.47536/jcrm.v3i1.896.
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Organochlorine (OC) contaminant concentrations in tissues and lipid profiles in blubber are summarised for 101 gray whales (Eschrichtius robustus) from the eastern North Pacific stock. Samples were obtained from presumably healthy gray whales during a 1994 subsistence hunt in the Russian Arctic (n = 17) and also from biopsy sampling of live animals from the Washington coast (n = 38). In addition, tissues were collected from two groups of animals (1988-1991, n = 22; and 1999, n = 24) that stranded along the west coast of the USA. These whales represent a diverse group of animals with respect to lipid stores, age, gender, health and reproductive status. Information about these biological factors is necessary before contaminant concentration data can be properly interpreted. Differences in blubber lipid levels and profiles were examined among these groups of whales. Significantly higher lipid levels were found in the blubber of subsistence animals that were sampled following summer feeding in the Bering and Chukchi Seas, compared to lipid levels in the biopsied and stranded animals. Lipid class profiles from blubber of presumably healthy gray whales (i.e. from subsistence and biopsy sampling) contained primarily triglycerides and were very different from those of stranded animals that showed lipid decomposition (increased proportions of free fatty acids, cholesterol and phospholipids). Furthermore, lipid class profiles were found to be a means of estimating the quality of a blubber sample from stranded cetaceans. An examination of how biological factors (e.g. gender, reproductive status, age) contribute to interpreting the differences found in contaminant concentrations among the gray whales was also undertaken. Although not statistically significant, higher (OC) concentrations were found in males compared to females, thus suggesting the tendency of the mother to shift her contaminant burden to her calf during gestation and lactation. Results also indicated that there was no significant increase in concentrations of contaminants in the blubber with increase in length (surrogate for age). Higher concentrations of OC contaminants were found in stranded juvenile gray whales, compared to juvenile subsistence whales, and were thought to result from retention of OCs in blubber of the stranded animals as lipid stores are mobilised for energy and total lipid levels decrease, rather than from a difference in diet or feeding areas. OC concentrations in various tissues (blubber, liver, kidney, muscle, brain) were similar on a lipid weight basis, except for brain, which had lower lipid-adjusted OCs because the blood-brain barrier limits contaminant transfer.
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Sturla Lompré, Julieta, Lucia De Marchi, João Pinto, Amadeu M. V. M. Soares, Carlo Pretti, Federica Chielini, Eduarda Pereira y Rosa Freitas. "Effects of Carbon Nanoparticles and Chromium Combined Exposure in Native (Ruditapes decussatus) and Invasive (Ruditapes philippinarum) Clams". Nanomaterials 13, n.º 4 (10 de febrero de 2023): 690. http://dx.doi.org/10.3390/nano13040690.
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Studies have described the occurrence of nanoparticles (NPs) in aquatic ecosystems, with particular attention to the widely commercialized carbon nanotubes (CNTs). Their presence in the environment raises concerns, especially regarding their toxicity when co-occurring with other pollutants such as metals. In the present study, changes to the metabolic capacity, oxidative, and neurologic status were evaluated in the presence of carboxylated multi-walled CNTs and chromium (Cr(III)) using two of the most ecologically and economically relevant filter feeder organisms: the clam species Ruditapes decussatus and R. philippinarum. Results indicated that although Cr, either alone or in combination with CNTs, was found in a similar concentration level in both species, a species-specific Cr accumulation was observed, with higher values in R. decussatus in comparison with R. philippinarum. Inhibition of antioxidant defenses and neurotoxic effects were detected only in R. philippinarum. The interaction between contaminants seems to have no effect in terms of antioxidant enzyme activities and neuro status. Nevertheless, synergistic activation of responses to both contaminants may have altered the metabolic capacity of bivalves, particularly evident in R. decussatus. While both clams are tolerant to both contaminants (alone and together), they showed a relevant accumulation capacity, which may represent a possible contaminant transfer to humans.
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Ding, J. Y. y S. C. Wu. "Laboratory Studies of the Effects of Dissolved Organic Material on the Adsorption of Organochlorine Pesticides by Sediments and Transport in Rivers". Water Science and Technology 28, n.º 8-9 (1 de octubre de 1993): 199–208. http://dx.doi.org/10.2166/wst.1993.0619.
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In this study experiments simulating sediment/water system were carried on with sediments spiked with aldrin, heptachlor epoxide and p,p'-DDE. It was expected that these hydrophobic contaminants would be released to the overlying water column from sediment bed with molecular diffusion and co-diffusion with dissolved organic matter (DOM) as well. A three-phase-transport model including aqueous, solid and mobile adsorptive phases was developed and used to describe the behavior of these contaminants and to explain the results of the experiments. Sensitivity analyses show that observable effects of DOM occur only under conditions of high partition coefficient (Koc) of the contaminant and high rate of transfer from sediment organic matter to DOM. In this study, owing to the low concentration of DOM and relatively low hydrophobicity of the compounds, the DOM-associated pollutant flux does not significantly contribute to the total flux. Also, the simulated results of the model can reasonably explain the variations of the concentrations of the spiked compounds observed in the microcosms.
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Nassar, Ibrahim M., Heba Nassar, Mohyeddin Assali, Muath H. S. Helal, Hyobin Han, Tae Woo Kim, Mazen Salman y Hikmat S. Hilal. "Electro-Mineralization of Aqueous Phenazopyridine Using Platinum Nanoparticles Deposited onto Multiwalled Carbon Nanotubes". Processes 12, n.º 8 (2 de agosto de 2024): 1625. http://dx.doi.org/10.3390/pr12081625.
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Water may easily become polluted by pharmaceutical wastes, such as phenazopyridine hydrochloride. The pollutant can be removed by electrochemical oxidation in the form of minerals. A novel electrode has been developed for this purpose. Pt nanoparticles (PtNPs) are electrodeposited onto multiwalled carbon nanotubes supported onto fluorine-doped tin oxide (FTO/Glass). The resulting PtNP@MWCNT-FTO-E electrode is characterized by X-ray diffraction, atomic force microscopy, scanning electron microscopy, electron diffraction spectroscopy and X-ray photoelectron spectroscopy. The electrode exhibits high efficiency in the electrochemical oxidation process thanks to the large specific surface area of the PtNPs and their ability to behave as charge transfer catalysts. The contaminant undergoes complete mineralization, leaving no organics after treatment. The resulting nitrate ions further confirm contaminant mineralization, but fortunately, they disappear over time, which confirms the safety of the process in water treatment. Moreover, the electrode operates under a variety of applied potentials, pH values, temperatures and contaminant concentrations. The electrode exhibits high stability upon recovery and reuse while retaining its physical characteristics before and after use. This study highlights the benefit of using Pt nanoparticles in the electro-degradation of aqueous organic contaminants, especially waste pharmaceuticals, for the first time. It also recommends scaling up the process and studying the continuous-flow reaction process to assess the economic and technical feasibility in future large-scale applications.
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Brandely, Maxime, Samuel Coussy, Denise Blanc-Biscarat, Remy Gourdon y Gaëtan Blanck. "Chemical Stabilization Used to Reduce Geogenic Selenium, Molybdenum, Sulfates and Fluorides Mobility in Rocks and Soils from the Parisian Basin". Environments 9, n.º 7 (25 de junio de 2022): 78. http://dx.doi.org/10.3390/environments9070078.
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Rocks and soils excavated from civil works frequently present high concentrations of naturally occurring leachable (oxy-)anions. This situation raises concerns regarding the potential transfer of contaminants to groundwater in a storage scenario. This study was carried out to give practical insights on the ability of various stabilizing agents to reduce molybdenum (Mo), selenium (Se), fluorides and sulfates mobility in four types of naturally contaminated excavated materials. Based on standardized leaching tests results, Mo and Se were effectively immobilized after zero valent iron or iron salts additions. Although alkaline materials were found to effectively reduce fluorides and sulfates mobility, their addition occasionally caused a subsequent increase in Mo and Se leaching due to pH increase. None of the reagents tested allowed a simultaneous immobilization of all (oxy-)anions sufficient to reach regulatory threshold values. The remaining difficulties were related to: (i) sulfates leaching from gypsum-rich samples, (ii) fluorides leaching from clayey samples and (iii) Mo and sulfates mobility from tunnel muck. Altogether, the study revealed that the choice of stabilizing agents should be made depending on the speciation of the contaminant or else an opposite impact (i.e., increase in contaminant mobility) might be triggered.
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McKone, Thomas E. y Randy L. Maddalena. "Soil Contamination and Human Exposure: A Comprehensive Assessment Framework". International Journal of Toxicology 16, n.º 4-5 (julio de 1997): 319–37. http://dx.doi.org/10.1080/109158197226991.
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Soil is the thin outer zone of the earth's crust that supports rooted plants and is the product of climate and living organisms acting on rock. Throughout the world, soils are contaminated to some extent by local, regional, and global pollution sources of both natural and human origin. Sources of soil contamination are identified and discussed. With the possible exception of agricultural applications of pesticides and fertilizers, most contaminant releases to soil are not easily quantified and, as a result, remain highly uncertain. In establishing a comprehensive framework for human exposure to soil contaminants, it is revealed that such exposure occurs through multiple transfer processes. The process for linking human exposure to soil contact is considered and it is found that the magnitude and persistence of exposure depend not only on the level of soil contamination but also on physical and chemical properties of soil, chemical properties of the contaminant, and the frequency and duration of human factors such as occupational and recreational activities or the consumption of home-grown food, which result in direct and indirect soil contact. All of these factors possess some degree of variance that leads to probability distributions for representing total exposure and risk.
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Hsu, Shu-Chen, Ting-Khai Kong, Chung-Yu Chen y Hsiu-Ling Chen. "Plasma-Activated Water Affects the Antioxidant Contents in Water Spinach". Applied Sciences 13, n.º 5 (6 de marzo de 2023): 3341. http://dx.doi.org/10.3390/app13053341.
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Several studies suggested that plasma-activated water (PAW) increases crop yields and confronts drought. This study determined the total phenolic (TP) and total flavonoid (TF) contents of water spinach to elucidate whether PAW induced changes in the antioxidant potential of water spinach planted in soil with and without metal contaminants. PAW was selected as the irrigation water for pot experiments. Results showed that PAW increased the TP of water spinach planted in soil without any contaminants and, to some extent, in Cd-added soils but decreased the TP of those planted in Pb-added soil. PAW significantly enhanced the TF of water spinach planted in Cd-added cultivation soil, but not for Pb-added cultivation soil. Meanwhile, PAW can elevate the TF of water spinach by adding fertilizer and sunlight exposure. This study demonstrated that PAW application could increase TF, powerful antioxidants of water spinach planted with fertilizer and sunlight, in the cultivation soil with Cd, or without any contaminant.
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Yao, Yu, Peifang Wang y Chao Wang. "The Influence on Contaminant Bioavailability and Microbial Abundance of Lake Hongze by the South-to-North Water Diversion Project". International Journal of Environmental Research and Public Health 16, n.º 17 (23 de agosto de 2019): 3068. http://dx.doi.org/10.3390/ijerph16173068.
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The world famous South-to-North Water Transfer Project was built to alleviate serious water shortages in northern China. Considering that lake Hongze is an important freshwater lake in this region, analyzing the influence of water diversion on typical contaminant bioavailability and microbial abundance could aid in achieving a good overall understanding of hydrodynamic variation. Accordingly, in situ high-resolution measurements of diffusive gradients in thin films (DGT) and next-generation high-throughput sequencing were combined in order to survey Lake Hongze and determine the relationship between environmental factors and microbial communities. The DGT method effectively obtained more than the 85% of bioavailable concentrations of the corresponding contaminants; the results showed that labile P, S, Fe, As, and Hg concentrations were higher in areas influenced by water transfer. Moreover, the relative abundance and alpha diversity of the sampling sites distributed in the water transfer area differed significantly from other sites. The pH, conductivity, and labile Mn, As, and P were shown to be the primary environmental factors affecting the abundance and diversity of microbes. With the exception of bioturbation-affected sites controlled by labile Mn and pH, sites distributed in the water diversion area were most affected by As and conductivity, with little spatial discrepancy. Furthermore, site 2, with higher bioturbation abundance, and site 10, with stronger hydrodynamics, had low alpha diversity compared to the other sites. Consequently, the bioavailability of typical contaminants such as P, S, As, Hg, Fe, Mg, Cd, Pb, and Mn, as well as the diversity and abundance of microbial in the sites influenced by the water diversion, were significantly different to the other sites. Thus, the impacts of the South-to-North Water Transfer Project on participant lakes were non-negligible overall in the investigation.
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Zhang, J. G., W. C. Zegel y U. H. Kurzweg. "Enhanced Axial Dispersion in Oscillating Pipe Flow With Different Solute Concentrations at Its Ends". Journal of Fluids Engineering 118, n.º 1 (1 de marzo de 1996): 160–65. http://dx.doi.org/10.1115/1.2817495.
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The problem of the enhanced axial contaminant dispersion by sinusoidal oscillation of fluid in a cylindrical pipe connected to reservoirs filled with contaminated groundwater involving different concentrations of species has been examined. It is found that the axial contaminant transfer along the pipe can be greatly enhanced by the fluid oscillation, which leads to a rapid removal of contaminants from groundwater and develops a relative low concentration region in the neighborhood of the subsurface collector. The enhanced dispersion coefficients, Deff, of several heavy metal ions and organic compounds with water as carrying fluid were computed, and the results show they are about four to six orders of magnitude larger than those in the absence of fluid oscillation. The operational energy cost is low. For example, by operating the presented U-type enhanced mass pump, whose total cross-section area in one leg is 0.0154 m2, it takes 15 days to extract and remove acetone from a contaminated groundwater body that is 12 m below grade and 10 m3 in volume, such that the acetone concentration can be decreased from 650 mg/l to 325 mg/l (i.e:, 50 percent lower than its original level) and the averaged daily (24 hours) operational energy cost is only 12.6 kJ (1.56 Btu).
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Zhang, Peng Wei, Qing Bo Wen y Li Ming Hu. "Numerical Simulation of Contaminant Dynamic Transfer in Dual-Domain Model". Advanced Materials Research 864-867 (diciembre de 2013): 1379–85. http://dx.doi.org/10.4028/www.scientific.net/amr.864-867.1379.
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Preferential flowpaths (PFP) causes highly heterogeneity of soil. In this study a preferential flowpaths generalized model has been established, based on dual-domain model (DDM) which reflects contaminant transport and the dynamic transfer between mobile and immobile domains, quantitatively analyses the contaminant mass transfer in pore scale at three different conditions. Besides, define relative hydraulic conductivity reflect the impact of PFP physical parameters, results show that it can affect the contaminant transport form and the distribution of contaminant concentration.
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Wolfenden, A. y MI Ismail. "Basic Principles of Contaminant Transfer Modeling". Journal of Testing and Evaluation 15, n.º 5 (1987): 274. http://dx.doi.org/10.1520/jte11021j.
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Laoubi, A. y J. M. Vergnaud. "Processes of Contaminant Transfer into Foods by Diffusion-Convection or by Diffusion from Packaging Made of a Recycled Layer and a Functional Barrier". Engineering Plastics 4, n.º 6 (enero de 1996): 147823919600400. http://dx.doi.org/10.1177/147823919600400602.
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Reusing old plastics as food packaging necessitates the presence of a functional barrier (made of a virgin polymer) between the food and old plastics. The transfer of the potent contaminant through the packaging is controlled by diffusion, leaving aside of the transfer of the food into the packaging. Depending on whether the food is liquid or solid, the process of transfer of the contaminant in the food is controlled either by convection, with a coefficient of convective transfer in the food, or by diffusion. The two processes have been studied in detail and the results are expressed in terms of master curves. Some emphasis is put on the effect of the value of the diffusivity in the food and of the coefficient of mass transfer on the contaminant transfer into the food.
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Laoubi, A. y J. M. Vergnaud. "Processes of Contaminant Transfer into Foods by Diffusion-Convection or by Diffusion from Packaging Made of a Recycled Layer and a Functional Barrier". Polymers and Polymer Composites 4, n.º 6 (septiembre de 1996): 397–405. http://dx.doi.org/10.1177/096739119600400602.
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Reusing old plastics as food packaging necessitates the presence of a functional barrier (made of a virgin polymer) between the food and old plastics. The transfer of the potent contaminant through the packaging is controlled by diffusion, leaving aside of the transfer of the food into the packaging. Depending on whether the food is liquid or solid, the process of transfer of the contaminant in the food is controlled either by convection, with a coefficient of convective transfer in the food, or by diffusion. The two processes have been studied in detail and the results are expressed in terms of master curves. Some emphasis is put on the effect of the value of the diffusivity in the food and of the coefficient of mass transfer on the contaminant transfer into the food.
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Hatcher, S., S. Hatcher, R. J. Lightfoot, R. J. Lightfoot, I. W. Purvis y I. W. Purvis. "Transfer of contaminant lamb fibres to their dam’s fleece, and loss within four weeks of weaning". Australian Journal of Experimental Agriculture 40, n.º 3 (2000): 371. http://dx.doi.org/10.1071/ea98170.
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The fleeces of Merino ewes suckled by Awassi, Awassi × Merino or Merino lambs were analysed for the presence of contaminant fibres (pigmented, urine-stained and kemp). Contaminant fibres were transferred from the fleeces of all 3 lamb genotypes into the fleeces of their dams, with direct body contact being the principle method of fibre transfer. The pattern of the transfer between birth and weaning was highly variable, although there was a general trend of increasing amount of transfer with advancing lamb age, suggesting a continual cycle of transfer of fibres to the dam’s fleece and subsequent loss from that fleece. Indeed, the number of fibres transferred tended to decrease rapidly post-weaning, when the source of the contaminant fibres (i.e. the lambs) was removed. Shearing of Merino breeding ewes, regardless of the genotype of their lambs, (i.e. pure Merino or crossbred), should be delayed until 4 weeks post-weaning in order to reduce the number of contaminant fibres of lamb origin in their fleeces.