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651.
Polybrominated diphenyl ethers (PBDEs) are chemicals of environmental concern due to their lipophilic, persistent and bioaccumulable characteristics as well as for their potential endocrine disrupting role. Former studies carried out in a tributary of the Cinca river (Ebro basin, NE Spain) revealed high levels of PBDEs in fish due to the discharges of effluents rich in PBDEs coming from a nearby industrial park in Barbastro. In this study, several biomarkers of pollutants exposure were measured in barbel, Barbus graellsii, before (upstream) and after (downstream) the main industrial site (Barbastro) in the Vero river. The results evidenced an enhanced hepatic phase I and II metabolism (measured as reductases, glutathione S transferase and uridinediphospho-glucuronosyltransferase), and of the antioxidant enzyme glutathione peroxidase. Conversely, fishes collected from downstream reaches had their phase I CYP1A dependent ethoxyresorufin O-deethylase, antioxidant diaphorase and brain cholinesterase activities depleted. In addition, the histological study of the liver and kidney of these fish evidenced an increase of the number and size of macrophage aggregates in most individuals collected downstream. Bivariate correlated analyses showed that the above mentioned biomarkers were correlated to measured PBDE congeners, thus indicating that the observed biological effects were unlikely to be related to other environmental factors than PBDEs. Overall, the measured biochemical and histological markers provide new evidence that in field exposed fish, PBDEs levels were associated with high activities of phase I and II metabolic enzymes, oxidative stress in liver, neurotoxicity in brain and histopathological effects in both liver and kidney.  相似文献   
652.
Soils of the Pampas show no signs of contamination with potentially toxic elements (PTEs), except in the areas that surround cities. The concentration of PTE in crops grown in this region is in most cases unknown. Our objective was to determine the PTE concentration in main field crops and pastures grown in 'a priori' non-contaminated areas and in potentially contaminated areas around cities. Forty-eight plots from farms located far from cities or roads and 36 plots from farms located very close to cities or to high traffic roads were sampled. The area ranged from 33 degrees 40' S to 36 degrees 0' S and from 57 degrees 35' W to 61 degrees 22' W. Maize, soybean, wheat, grazed grassland and pastures, and their top soils were sampled. All samples were acid digested. Cadmium, zinc, chromium, copper, nickel and lead were determined using ICPES. Standard t-tests were performed. All soils were within the known normal values of soil PTE concentrations, with the exception of a few cases around cities. PTE accumulation on grains and aerial biomass is considered almost negligible in crops grown in both studied areas, with the exception of a few elements in soybean. PTE concentrations in crops and pastures are in keeping with the low content of trace metals found in soils of the Pampas.  相似文献   
653.
Biodiversity Hotspots and Zones of Ecological Transition   总被引:2,自引:0,他引:2  
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654.
This study evaluates and compares the effectiveness of solar photo–Fenton systems for the inactivation of hepatitis A virus (HAV) in water. The effect of solar irradiance, dark- Fenton reaction and three different reactant concentrations (2.5/5, 5/10 and 10/20 mg/L of Fe2+/H2O2) on the photo–Fenton process were tested in glass bottle reactors (200 mL) during 6 h under natural sunlight. Disinfection kinetics were determined both by RT-qPCR and infectivity assays. Mean water temperatures ranged from 25 to 27.3 °C, with a maximum local noon UV irradiances of 22.36 W/m2. Photo–Fenton systems yielded increased viral reduction rates in comparison with the isolated effect under the Fenton reaction in darkness (negligible viral reduction) or the solar radiation (0.25 Log of RNA reduction). With the highest concentration employed (10–20 mg/L Fe2+–H2O2), an average RNA reduction rate of ~ 1.8 Log (initial concentration of 105 pfu/mL) and a reduction of 80% in the infectivity capacity were reached. Results showed a strong synergistic effect between Fe2+/H2O2 and sunlight, demonstrating that significant disinfection rates of HAV under photo–Fenton systems may occur with relatively higher efficiency at middle environmental temperatures and without the need for an energy-intensive light source.  相似文献   
655.
The widespread use of polymeric materials in many applications requires polymers that are weather resistant. The aim of this study is to examine the usefulness of oxidation onset temperature measurements as a tool for evaluating oxidative degradation of isotatic polypropylene. Differential scanning calorimetry was used to measure the oxidation onset temperature in formulations of isotatic polypropylene containing different concentrations of light and thermal stabilizers after aging in a Weather-Ometer. Oxidation onset temperature gave better results than oxidation induction time for evaluating the degradation of isotatic polypropylene during aging in a Weather-Ometer. However, both tests showed a poor correlation with the appearance of cracks seen by optical microscopy.  相似文献   
656.
Activities of glutathione S-transferases (GST) and cholinesterase (ChE) from Paracentrotus lividus were investigated as possible biomarkers of environmental contamination in the coastal zone. In the first phase of the study, the activity of both enzymes was determined in various tissues in order to select the most appropriate ones to be used in the following assays. In the second phase, the ChEs present in ambulacra were characterized using different substrates and selective inhibitors. In the next phase, laboratory bioassays were performed with dilutions of water-accommodated fraction of #4 fuel-oil (WAF) and benzo[a]pyrene (BaP) to determine the response of those enzymes to these pollutants and, finally, the activity of both enzymes was determined during a year in indigenous specimens from six sites on the Northwest coast of Portugal, with different pollution levels, to determine basal values and seasonal variations of ChE and GST activities. Among the several tissues tested, ambulacra and the anterior portion of the intestine were selected for ChE and GST assays, respectively. The determination of ChE in ambulacra tissue may be performed in a non-destructive way. Ambulacra ChE hydrolysed acetylthiocholine preferentially to propionylthiocholine and butyrylthiocholine and, inhibition by excess of substrate was observed. Enzymatic activity was almost fully inhibited by eserine sulfate (>98%) at concentrations equal or higher than 6.25 microM. Sensitivity to both BW284C51 (reaching 98% at 200 microM) and iso-OMPA (73% at 8 mM) was found. In laboratory bioassays, GSTs activity was inhibited by WAF and induced by BaP, whereas ChE activity was not affected by any of these environmental contaminants. Seasonal variations in enzymatic activities were found. For example, in a reference site, ChE values changed from 52.2 +/- 9.3 U mg(-1) protein in autumn to 71.8 +/- 13.3 U mg(-1) protein in spring, while GST activity changed from 129.9 +/- 29.8 U mg(-1) protein in winter to 279.0 +/- 48.0 U mg(-1) protein in autumn. Sea-urchins from reference sites presented significantly higher values of both ChE and GST than animals from contaminated sites in all seasons. In conclusion, the results of this study indicate that (i) ambulacra and the anterior portion of intestine are the most suitable tissues to measure ChE and GST activities, respectively; (ii) only one form of ChE seems to be present in ambulacra, showing properties of both typical acetylcholinesterase (AChE) and pseudocholinesterase (PChE); (iii)P. lividus GST is sensitive to both WAF and BaP even after acute exposures while ChE is not, and (iv) in spite of the significant seasonal variations observed in both enzymes in the field, P. lividus ChE and GST were capable of discriminate sites with different contamination levels and, thus, they are suitable for use as biomarkers in biomonitoring studies in the coastal zone.  相似文献   
657.
658.
In the last few years, many organizations have chosen to implement standardized Management Systems (MSs), such as the ones based on ISO 14001 and ISO 9001. However, few studies exist on how firms carry out the process of auditing these MSs.Our goal is to study how companies with more than one standardized MSs conduct the audits and to which extent they integrate the audit elements in order to benefit from the advantages of having a sole, integrated audit system.We provide four case studies and confirm the idea that firms with more than one MS integrate their audits. However, the degree and specific characteristics of this integration vary in the different companies analyzed.This paper contains one of the first qualitative empirical studies regarding the integration of MSs audits. The study provides an original contribution to the understanding of whether and how the four case study organizations have integrated certain aspects of the audit systems, for instance, the human resources, time, and audit inputs and outputs.  相似文献   
659.
The development and implementation of new procedures and operational changes in the production processes constitutes a powerful tool for the practical application of Cleaner Production in industries. In this work an operational change (new procedure) was developed for the elaboration of a type of beer which uses sugar as malt adjunct. The change consists in processing separately the three main components of the beer wort: malt extract, sugar and water, and use them properly in a different sequence than that used up to date in the traditional process. The new procedure was successfully assayed on industrial scale in Tínima brewery, located in Camagüey, Cuba, obtaining a good quality beer, technological and economical advantages with benefits for the environment, registering significant savings in energy (49%), sugar (4%), water (7%) and caustic soda (3%) consumption; and diminishing the surplus hot water (74%), waste generation (11%) and greenhouse gases emission (21%). Beer production capacity is increased also almost three times. With the application of the new technology to the Cuban beer type of 8 °P, it was achieved a total saving of US$ 481.83/1000 hL of beer produced.  相似文献   
660.
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