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Resultados 1591-1600 de 2,459
A step forward using QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) based extraction and gas chromatography-tandem mass spectrometry—levels of priority polycyclic aromatic hydrocarbons in wild and commercial mussels
2014
Madureira, Tânia Vieira | Velhote, Susana | Santos, Claudia | Cruzeiro, Catarina | Rocha, Eduardo | Rocha, Maria João
A new and fully validated QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) extraction and gas chromatography–tandem mass spectrometry methodology was developed and subsequently implemented for the quantification of 16 polycyclic aromatic hydrocarbons (PAHs) in wild (from Matosinhos Beach, Portugal) and commercial (from Ria de Arousa, Spain) mussels. The method proved to be robust, precise, and accurate, with recoveries ranging from 89.2 to 111.8 %. Total sums of 16 PAHs were 52.91 and 37.58 ng/g of wet weight for wild and commercial specimens, respectively. The three- to four-ring PAHs were the most abundant, and a mixture of petrogenic and pyrolytic sources were suspected to occur in both origin areas. Although the contamination levels were below the European regulated limits, specifically for commercial mussels (this despite wild specimens are also consumed), care should be taken in terms of human health, since we are still not aware of the low-dose versus long-term effects, even more in high-risk population groups.
Mostrar más [+] Menos [-]Assessment of the effects of nickel on benthic macroinvertebrates in the field
2014
Peters, Adam | Simpson, Peter | Merrington, Graham | Schlekat, Chris | Rogevich-Garman, Emily
A field-based evaluation of the biological effects of potential nickel (Ni) exposures was conducted using monitoring data for benthic macroinvertebrates and water chemistry parameters for streams in England and Wales. Observed benthic community metrics were compared to expected community metrics under reference conditions using RIVPACS III+ software. In order to evaluate relationships between Ni concentrations and benthic community metrics, bioavailable Ni concentrations were also calculated for each site. A limiting effect from Ni on the 90th percentile of the maximum achievable ecological quality was derived at “bioavailable Ni” exposures of 10.3 μg l⁻¹. As snails have been identified as particularly sensitive to nickel exposure, snail abundance in the field in response to nickel exposure, relative to reference conditions, was also analysed. A “low effects” threshold for snail abundance based on an average of spring and autumn data was derived as 3.9 μg l⁻¹bioavailable Ni. There was no apparent effect of Ni exposure on the abundance of Ephemeroptera (mayflies), Plecoptera (stoneflies) or Tricoptera (caddisflies) when expressed relative to a reference condition within the range of “bioavailable Ni” exposures observed within the dataset. Nickel exposure concentrations co-vary with the concentrations of other stressors in the dataset, and high concentrations of Ni are also associated with elevated concentrations of other contaminants.
Mostrar más [+] Menos [-]Relationship of metal enrichment with adverse biological effect in the Yangtze Estuary sediments: role of metal background values
2014
Zhao, Shou | Feng, Chenghong | Wang, Dongxin | Tian, Chenhao | Shen, Zhenyao
Exclusive pristine values of As, Cd, Cr, Cu, Fe, Mn, Pb, and Zn in the Yangtze Estuary are calculated using principal components analysis (PCA) to probe the relationship between degrees of metal enrichment and their adverse biological effects. The results show that obvious differences in the degrees of metal enrichment exist when the enrichment factors are analyzed with reference background values on global, national, and local scales. Based on the low variability of aluminum, the exclusive metal background values in the estuary are obtained with PCA and are more likely to reflect the pristine contents of the abovementioned metals in the Yangtze Estuary. For the six most common metals (As, Cd, Cr, Cu, Pb, and Zn), significant correlations exist between the enrichment factors and their adverse biological effects. Arsenic shows the highest potential to cause adverse effects despite its general lack of enrichment. However, Cd is the most conservative element and is not likely to cause biological effects in the estuary.
Mostrar más [+] Menos [-]Spatial variability of metallic and organic contamination of anguilliform fish in New Caledonia
2014
Briand, M. J. | Letourneur, Y. | Bonnet, X. | Wafo, E. | Fauvel, T. | Brischoux, F. | Guillou, G. | Bustamante, P.
New Caledonia is one of the main hot spots of biodiversity on the planet. Large amounts of contaminants are discharged into the lagoon as a result of increasing anthropogenic activities such as intense mining, urbanization, and industrialization. Concentrations of 14 trace elements and 26 persistent organic pollutants (POPs: PCBs and pesticides) were measured in the muscles of two anguilliform fish species, over a coast to barrier reef gradient in two lagoon areas differently exposed to anthropic disturbances. This study emphasizes the high trace element contamination status of anguilliform fish and also highlights slight but perceptible organic pollution. The contamination extends throughout the lagoon, from coast to barrier reef, even in areas remote from emission points. High levels of trace elements, especially those linked to mining activities (i.e., Co, Cr, Fe, Mn, and Ni), were detected in coastal sites. Furthermore, the large dispersion of most POPs throughout the entire lagoon poses the question of their potential toxicity on marine organisms from numerous habitats. Our results underline the need for long-term monitoring of various contaminants over large spatial and time scales.
Mostrar más [+] Menos [-]Functional models for colloid retention in porous media at the triple line
2014
Dathe, Annette | Zevi, Yuniati | Richards, Brian K. | Gao, Bin | Parlange, J-Yves | Steenhuis, Tammo S.
Spectral confocal microscope visualizations of microsphere movement in unsaturated porous media showed that attachment at the Air Water Solid (AWS) interface was an important retention mechanism. These visualizations can aid in resolving the functional form of retention rates of colloids at the AWS interface. In this study, soil adsorption isotherm equations were adapted by replacing the chemical concentration in the water as independent variable by the cumulative colloids passing by. In order of increasing number of fitted parameters, the functions tested were the Langmuir adsorption isotherm, the Logistic distribution, and the Weibull distribution. The functions were fitted against colloid concentrations obtained from time series of images acquired with a spectral confocal microscope for three experiments performed where either plain or carboxylated polystyrene latex microspheres were pulsed in a small flow chamber filled with cleaned quartz sand. Both moving and retained colloids were quantified over time. In fitting the models to the data, the agreement improved with increasing number of model parameters. The Weibull distribution gave overall the best fit. The logistic distribution did not fit the initial retention of microspheres well but otherwise the fit was good. The Langmuir isotherm only fitted the longest time series well. The results can be explained that initially when colloids are first introduced the rate of retention is low. Once colloids are at the AWS interface they act as anchor point for other colloids to attach and thereby increasing the retention rate as clusters form. Once the available attachment sites diminish, the retention rate decreases.
Mostrar más [+] Menos [-]Pacific oyster (Crassostrea gigas) hemocyte are not affected by a mixture of pesticides in short-term in vitro assays
2014
Moreau, Pierrick | Burgeot, Thierry | Renault, Tristan
Pesticides are frequently detected in estuaries among the pollutants found in estuarine and coastal areas and may have major ecological consequences. They could endanger organism growth, reproduction, or survival. In the context of high-mortality outbreaks affecting Pacific oysters, Crassostrea gigas, in France since 2008, it appears of importance to determine the putative effects of pesticides on oyster susceptibility to infectious agents. Massive mortality outbreaks reported in this species, mainly in spring and summer, may suggest an important role played by the seasonal use of pesticides and freshwater input in estuarine areas where oyster farms are frequently located. To understand the impact of some pesticides detected in French waters, their effects on Pacific oyster hemocytes were studied through short-term in vitro experiments. Bivalve immunity is mainly supported by hemocytes eliminating pathogens by phagocytosis and producing compounds including lysosomal enzymes and antimicrobial molecules. In this study, oyster hemocytes were incubated with a mixture of 14 pesticides and metaldehyde alone, a molecule used to eliminate land mollusks. Hemocyte parameters including dead/alive cells, nonspecific esterase activities, intracytoplasmic calcium, lysosome number and activity, and phagocytosis were monitored by flow cytometry. No significant effect of pesticides tested at different concentrations was reported on oyster hemocytes maintained in vitro for short-term periods in the present study. It could be assumed that these oyster cells were resistant to pesticide exposure in tested conditions and developing in vivo assays appears as necessary to better understand the effects of pollutants on immune system in mollusks.
Mostrar más [+] Menos [-]Physiological and transcriptional responses of Baccharis halimifolia to the explosive “composition B” (RDX/TNT) in amended soil
2014
Ali, Asjad | Zinnert, Julie C. | Muthukumar, Balasubramaniam | Peng, Yanhui | Chung, Sang-Min | Stewart, C. Neal, Jr
Unexploded explosives that include royal demolition explosive (RDX) and trinitrotoluene (TNT) cause environmental concerns for surrounding ecosystems. Baccharis halimifolia is a plant species in the sunflower family that grows naturally near munitions sites on contaminated soils, indicating that it might have tolerance to explosives. B. halimifolia plants were grown on 100, 300, and 750 mg kg⁻¹of soil amended with composition B (Comp B) explosive, a mixture of royal demolition explosive and trinitrotoluene. These concentrations are environmentally relevant to such munitions sites. The purpose of the experiment was to mimic contaminated sites to assess the plant’s physiological response and uptake of explosives and to identify upregulated genes in response to explosives in order to better understand how this species copes with explosives. Stomatal conductance was not significantly reduced in any treatments. However, net photosynthesis, absorbed photons, and chlorophyll were significantly reduced in all treatments relative to the control plants. The dark-adapted parameter of photosynthesis was reduced only in the 750 mg kg⁻¹Comp B treatment. Thus, we observed partial physiological tolerance to Comp B in B. halimifolia plants. We identified and cloned 11 B. halimifolia gene candidates that were orthologous to explosive-responsive genes previously identified in Arabidopsis and poplar. Nine of those genes showed more than 90 % similarity to Conyza canadensis (horseweed), which is the closest relative with significant available genomics resources. The expression patterns of these genes were studied using quantitative real-time PCR. Three genes were transcriptionally upregulated in Comp B treatments, and the Cytb6f gene was found to be highly active in all the tested concentrations of Comp B. These three newly identified candidate genes of this explosives-tolerant plant species can be potentially exploited for uses in phytoremediation by overexpressing these genes in transgenic plants and, similarly, by using promoters or variants of promoters from these genes fused to reporter genes in transgenic plants for making phytosensors to report the localized presence of explosives in contaminated soils.
Mostrar más [+] Menos [-]Eutrophic urban ponds suffer from cyanobacterial blooms: Dutch examples
2014
Waajen, Guido W. A. M. | Faassen, Elisabeth J. | Lürling, Miquel
Ponds play an important role in urban areas. However, cyanobacterial blooms counteract the societal need for a good water quality and pose serious health risks for citizens and pets. To provide insight into the extent and possible causes of cyanobacterial problems in urban ponds, we conducted a survey on cyanobacterial blooms and studied three ponds in detail. Among 3,500 urban ponds in the urbanized Dutch province of North Brabant, 125 showed cyanobacterial blooms in the period 2009–2012. This covered 79 % of all locations registered for cyanobacterial blooms, despite the fact that urban ponds comprise only 11 % of the area of surface water in North Brabant. Dominant bloom-forming genera in urban ponds were Microcystis, Anabaena and Planktothrix. In the three ponds selected for further study, the microcystin concentration of the water peaked at 77 μg l⁻¹and in scums at 64,000 μg l⁻¹, which is considered highly toxic. Microcystin-RR and microcystin-LR were the most prevalent variants in these waters and in scums. Cyanobacterial chlorophyll-a peaked in August with concentrations up to 962 μg l⁻¹outside of scums. The ponds were highly eutrophic with mean total phosphorus concentrations between 0.16 and 0.44 mg l⁻¹, and the sediments were rich in potential releasable phosphorus. High fish stocks dominated by carp lead to bioturbation, which also favours blooms. As urban ponds in North Brabant, and likely in other regions, regularly suffer from cyanobacterial blooms and citizens may easily have contact with the water and may ingest cyanobacterial material during recreational activities, particularly swimming, control of health risk is of importance. Monitoring of cyanobacteria and cyanobacterial toxins in urban ponds is a first step to control health risks. Mitigation strategies should focus on external sources of eutrophication and consider the effect of sediment P release and bioturbation by fish.
Mostrar más [+] Menos [-]Increase male genital diseases morbidity linked to informal electronic waste recycling in Guiyu, China
2014
Xu, Xijin | Zhang, Yuling | Yekeen, Taofeek Akangbe | Li, Yan | Zhuang, Bingrong | Huo, Xia
In recent years, occupational and environmental exposure to toxic pollutants has increasingly contributed to declining sperm quality and increasing morbidity of human male genital diseases. This study explored the effects of electronic waste (e-waste) environmental pollutions on male genital health in Guiyu, one of the largest e-waste recycling centers in the world. We collected outpatient case information from 2001 to 2009 in Guiyu and a control hospital and performed statistical analysis on male genital diseases morbidity (MGDM). The MGDM in Guiyu and the control hospital per thousand from 2004 to 2009 were 1.410/0.403 (2004), 0.539/0.385 (2005), 0.248/0.284 (2006), 0.485/0.195 (2007), 1.107/0.272 (2008), and 0.741/0.586 (2009) while the average total MGDM from 2004 to 2009 were 0.753 and 0.355 per thousand, respectively. Percentage of occurrence of epididymitis, impotence and prospermia, redundant prepuce, gonorrhea, urethritis, sexual function dysfunction, azoospermia, asthenospermia, and unknown etiology male sterility were higher in Guiyu (P < 0.05), whereas the frequency of prostatitis, condyloma accuminatum, and genital herpes were higher in the control (P < 0.05). Morbidity of male genital diseases was higher in Guiyu than in the control area. Male reproductive health may be threatened by e-waste environmental pollution in Guiyu, especially for diseases that could be influenced by environmental factors, and it may influence local population diathesis.
Mostrar más [+] Menos [-]Outbreak of fatal nitrate toxicosis associated with consumption of fennels (Foeniculum vulgare) in cattle farmed in Campania region (southern Italy)
2014
Costagliola, Alessandro | Roperto, Franco | Benedetto, Domenico | Anastasio, Aniello | Marrone, Raffaele | Perillo, Antonella | Russo, Valeria | Papparella, Serenella | Paciello, Orlando
Nitrate and nitrite are toxicants that have become increasingly significant environmental chemicals. Increase in environmental distribution of nitrogenous compounds, especially in surface and ground water, has been attributed to the intensive use of nitrate as agricultural fertilizers and to increasing amounts of nitrogenous wastes produced by municipalities, industries, and feedlots. The purpose of this study is to illustrate a fatal nitrate toxicosis in cattle associated with the consumption of fennels (Foeniculum vulgare). Fifteen cows from the same farm suddenly developed weakness, muscular tremors, respiratory distress, and finally convulsions. The affected animals died within 24 to 48 h from the onset of the clinical signs. Five cows underwent a complete post-mortem examination. In all examined animals, gross lesions included presence of dark unclotted blood around the nostrils and the anal region, moderate inflammation of the gastrointestinal mucosa, and brown discoloration of the skeletal muscles and kidneys. The histological examination showed tubular degeneration and congestion of glomerular vessels in the kidney. Toxicological analysis detected nitrates at 4 672.2 ppm in the fennels used to feed the animals. The source of exposure to nitrates was identified in the fennels. The fennels were grown in a polluted area of the Campania region in southern Italy and distributed in a public market for human consumption. The waste from the sale of the fennels was fed to the cows. The accumulation of nitrates in some vegetables poses a risk not only for animal health but also for human and environmental safety.
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