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81.
Packing materials play a key role in the performance of bioreactors for waste gas treatment and particularly in biofilter applications. In this work, the performance of four differently packed biofilters operated in parallel for the treatment of relatively high inlet concentration of toluene was studied. The reactors were compared for determining the suitability of coconut fiber, digested sludge compost from a waste water treatment plant, peat and pine leaves as packing materials for biofiltration of toluene. A deep characterisation of materials was carried out. Biological activity and packing capabilities related to toluene removal were determined throughout 240 days of operation under different conditions of nutrients addition and watering regime. Also, biofilters recovering after a short shutdown was investigated. Nutrient addition resulted in improved removal efficiencies (RE) and elimination capacities (EC) of biofilters reaching maximum ECs between 75 and 95 g m(-3)h(-1) of toluene. In the first 80 days, the pH decreased progressively within the reactors, causing a population change from bacteria to fungi, which were the predominant decontaminant microorganisms thereafter. All reactors were found to recover the RE rapidly after a 5 days shutdown and, in a maximum of 7 days, all reactors had been completely recuperated. These results point out that fungal biofilters are a suitable choice to treat high loads of toluene. In general, coconut fiber and compost biofilters exhibited a better performance in terms of elimination capacity and long-term stability.  相似文献   
82.
Previous studies have used particle mass and size as metrics to link airborne particles with deleterious health effects. Recent evidence suggests that particle composition can play an important role in PM-toxicity; however, little is known about the specific participation of components (individually or acting in groups) present in such a complex mixture that accounts for toxicity. This work explores relationships among PM(10) components in order to identify their covariant structure and how they vary in three sites in Mexico City. Relationships between PM(10) with cell toxicity and geographical location were also explored. PM(10) was analyzed for elemental composition, organic and elemental carbon, endotoxins and the induction of inhibition of cell proliferation, IL-6, TNFalpha and p53. PM(10) variables were evaluated with principal component analysis and one-way ANOVA. The inhibition of cell proliferation, IL-6 and TNFalpha were evaluated with factorial ANOVA and p53 with the Welch test. The results indicate that there is heterogeneity in particle mass, composition and toxicity in samples collected at different sites. Multivariate analysis identified three major groups: (1) S/K/Ca/Ti/Mn/Fe/Zn/Pb; (2) Cl/Cr/Ni/Cu; and (3) endotoxins, organic and elemental carbon. Groups 1 and 3 showed significant differences among sites. Factorial ANOVA modeling indicated that cell proliferation was affected by PM concentration; TNFalpha and IL-6 by the interaction of concentration and site, and p53 was different by site. Radial plots suggest the existence of complex interactions between components, resulting in characteristic patterns of toxicity by site. We conclude that interactions of PM(10) components determine specific cellular outcomes.  相似文献   
83.
Sediments have long been recognised as a sink for many contaminants like polycyclic aromatic hydrocarbons (PAHs) and tributyltin (TBT), which by virtue of their nature can strongly adsorb onto sediments affecting the benthic community inhabiting them. Using geographical information systems, this study reports and combines the results of several already existing studies along Barcelona harbour in order to assess the potential ecological impacts of these contaminants on the benthos of the harbour ecosystem. Chemical analysis indicated low to moderate contents of PAHs and high contents of TBT in sediments in Barcelona harbour. Comparison against existing sediment quality guidelines (SQGs) indicated that acutely toxic effects would not be expected for PAHs but for TBT, which represents a serious environmental threat for the benthic community. Benthos surveys revealed a deterioration of the benthic community throughout the harbour, especially in the inner port.  相似文献   
84.
Many water-related problems are shared by most of the developing countries and the industrialized nations could be in position of offering aid in such problems. Water scarcity and access to safe water, water pollution, severe storms and floods, droughts, waterborne diseases and landslides and mud floods are the most commonly shared problems among developing nations. These problems were discussed in a workshop organized as part of the Fifth International Symposium on Environmental Hydraulics in 2008. The discussion included identification of actors both in the developing and developed nations (vgr. local and national governments, NGOs, universities, foundations and private and public research institutions), aid modalities such as education, technology transfer, technology development and direct investment as well as restrictions and barriers in the form of political and legal issues, economic limitations, cultural differences and geographic distances. Recommendations about how developed nations could help developing countries are issued.  相似文献   
85.
We recently demonstrated whole genome sequencing of a human fetus using only parental DNA samples and plasma from the pregnant mother. This proof-of-concept study demonstrated how samples obtained noninvasively in the first or second trimester can be analyzed to yield a highly accurate and substantially complete genetic profile of the fetus, including both inherited and de novo variation. Here, we revisit our original study from a clinical standpoint, provide an overview of the scientific approach, and describe opportunities and challenges along the path toward clinical adoption of noninvasive fetal whole genome sequencing. © 2013 John Wiley & Sons, Ltd.  相似文献   
86.
This study presents 30 cases of fetal isolated spina bifida aperta (SBA) to identify prenatal ultrasound findings that could predict the prognosis. Comparisons between surviving patients who had normal (group 1) and abnormal (group 2) post-natal neurological outcomes were made for three different prenatal signs, that is, site of vertebral lesion, presence and degree of ventriculomegaly and presence of talipes. The site of the lesion was the most significant outcome predictor, as high spinal dysraphisms were observed in 2 patients (2/7–28.6%) in group 1 and in 15 patients (15/19–79.0%) in group 2 (p = 0.03). The presence of fetal ventriculomegaly was associated with impaired post-natal neurological development, as it occurred in 4 patients (4/7–57.1%) in group 1 and in 18 patients (18/19–94.7%) in group 2 (p = 0.04). The presence of talipes did not significantly differ between the two groups. Patients with abnormal intellectual outcome (8/26–30.8%) had significantly greater (p = 0.018) lateral ventricle/hemisphere ratios (mean = 0.74, standard deviation = 0.13) than those with normal intellectual development (mean = 0.54, standard deviation = 0.18). Mean post-natal follow-up was at 23 months (standard deviation = 15 months). Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   
87.
The effectiveness of a frugivore as a disperser of a plant is greatly determined by how fruits and seeds are handled in its mouth and its digestive tract. Although a number of studies have investigated the effect of avian ingestion on germination, we still know very little about the modifications to seeds during ingestion and the specific consequences on plant fitness. Here we investigate for the first time the different mechanisms by which germination patterns of seeds are modified following ingestion by frugivores. Specifically, we examine changes in seed mass, water content, permeability, seed coat thickness, texture, and resistance in two common Mediterranean fleshy-fruited plants, Phillyrea angustifolia and Myrtus communis, after ingestion by Eurasian Blackbirds, Turdus merula. We found a number of differences between the plant species: Phillyrea seeds lost mass, mainly due to water loss, and had thinner coats after gut passage, but Myrtus seeds did not. Seeds of both species showed increased permeability, while Myrtus seeds in particular became less resistant to breakage. No quantifiable changes in seed coat texture were detected in either species, although this trait was partly associated with differences in germination rate in Phillyrea. High intraspecific plant variation was found for most seed traits measured. Seed passage through birds' guts sped up germination in both species, especially in Myrtus. Increased permeability in seeds of both species following ingestion resulted in a higher germination rate. Moreover, seeds with thick coats (and in the case of Phillyrea, harder coats) germinated at a slower rate and produced seedlings that also grew more slowly, indicating a cost of coat thickness and/or hardness for seedling emergence. Results obtained here contribute to explaining the great heterogeneity in germination responses among and within plant species and the large variety of factors, both intrinsic and extrinsic to the plants, that influence such responses.  相似文献   
88.
A wet air oxidation (WAO) process was applied to four selected pharmaceuticals (metoprolol, naproxen, amoxicillin, and phenacetin) individually dissolved in ultra-pure water, varying the temperature and oxygen pressure. Due to the moderate (amoxicillin) or low (metoprolol, naproxen, and phenacetin) efficiency found in the oxidation of these pollutants, a catalytic wet air oxidation (CWAO) process was then tested using a platinum catalyst supported on multi-walled carbon nanotubes (CNT). In this CWAO process, the pharmaceuticals were dissolved together in ultra-pure water and in four natural water matrices—a reservoir water, a groundwater, and two waters from different municipal wastewater treatment plants. On the basis of the measurements of their removals, a discussion is given of the influence of the main operating variables: the presence or absence of catalyst, type of catalyst (the synthesized Pt/CNT or a commercial Pt/AC), catalyst dosage (0.005–0.050 g), temperature (120–140 °C), and oxygen pressure (20–40 bar). In most experiments, the removals were in the sequence: amoxicillin > naproxen > phenacetin. In addition, total organic carbon (TOC) removal measurements were made of some of the natural waters tested.  相似文献   
89.
Valuing goods and services from open oceans provides arguments for the ocean's protection and plays an increasingly important role in debates on the use and management of natural resources. This paper identifies and estimates the monetary value of some of the most important goods and services provided by open oceans. The list of goods and services considered includes food production, raw materials, water supply, CO2 regulation, bioremediation of waste, biomass and biodiversity conservation. Therefore, not only values associated with productive uses are quantified but also values assigned to other biological ecosystem services. This paper constitutes a first attempt in the open ocean literature at evaluating services such as water supply, biomass and biodiversity conservation. To obtain their monetary value, different techniques, some not applied before in this area, have been used depending on the ecosystem service to be evaluated. As a general criterion we use the concept of net value added (revenues obtained from the services less incurred costs). Our methodology is illustrated by estimating the monetary values of goods and services provided by the open ocean ecosystem of Spain as defined by its exclusive economic zone. The total economic value obtained measures the contribution of oceans to overall welfare and it may be an important instrument in managing open ocean ecosystems and developing environmental policies in the future.  相似文献   
90.
This paper analyses both the processes of adoption and diffusion of the practice of using the chopped residues of pruning as mulch in the olive orchards of the Southern Spanish province of Granada, one of the major olive-producing areas in the world. Many olive groves in the area are located on steep areas where the risk of soil erosion is high. A majority of farmers have adopted no tillage, as an alternative to traditional tillage, combined with either vegetation soil covers or, more frequently, using the chopped pruning residues as mulch. The data used comes from a survey carried out in 2005 to 215 olive farmers. From farmers' responses we estimate a binomial probit model to identify some socio-economic and institutional factors related to the decision to use the practice of mulching on a regular basis. We also estimate several diffusion models that describe the spatial and temporal spread of mulching among farmers. Our results show that mulching using the pruning residues is adopted by 43% of the surveyed farmers. The diffusion process of this practice has been very intense since the middle nineties, and seems to have been based on the interactions among farmers in the area of study rather than in other external source of information. Some of the relevant identified factors that affect the probability of adoption of this practice are farmer's experience, the level of soil degradation in the farm or the continuity of farming by some relative.  相似文献   
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