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141.
The São Francisco River is the largest river located entirely within Brazil, and water scarcity problems have been a major concern of Brazilian society and government. Water quality issues are also a concern and have worsened with the recent intensification of urbanization and industrialization. In this study, violations to water quality standards established by local legislation were calculated as a percentage for 26 selected parameters over a monitoring period of 14 years. The violation percentages were analyzed spatially using the Kruskal-Wallis test, followed by multiple comparison analysis. Temporal analysis was performed using the Mann-Kendall test and Spearman correlation. Some parameters could be identified as cause for concern due to high violation levels, such as the fecal coliform indicator (FCI) and phosphorus—both related to domestic and effluent disposal without treatment or with insufficient treatment—and color, turbidity, manganese, and total suspended solids—which can be affected by erosive processes of natural and anthropogenic causes. The study found that these violations are concentrated in the most urbanized and industrialized areas of the basin. Some metallic parameters, such as iron and arsenic violations, may be related to mining activities in the rich soil of the Iron Quadrangle area located within the Minas Gerais State. Trend analysis results indicated that most monitoring stations did not have significant modification (elevation or reduction) trends over time, which, together with the high violation percentages, might indicate the maintenance of a scenario of constant pressure upon water resources, in particular in those more urbanized areas.  相似文献   
142.
Coastal areas are the focus of intensive urbanisation and tourism and are subject to changing physical processes causing significant natural environment modifications. It is in this context that the European Commission (EC) developed the Integrated Coastal Zone Management (ICZM) Recommendation and invited coastal Member States to produce national implementation strategies. Its general aim of sustainable coastal development was based on policy integration in cooperation with all stakeholders in an informed and participatory context. Portugal responded to the EC request by creating, approving, and adopting the national ICZM strategy. This paper focuses on Portuguese experiences putting the ICZM recommendation into practice and begins with a brief overview of community guidelines, national legislation, and implementation. Subsequently, governance mechanisms are discussed and best practice identified. From an assessment of Portuguese ICZM progress and lessons learned, conclusions and recommendations for improved effectiveness included: strengthening governance; improving sustainable decision-making processes supported by technical and scientific knowledge; and securing financial sustainability.  相似文献   
143.
Oxidative stress generating active oxygen species has been proved to be one of the underlying agents causing tissue injury after the exposure of Eucalyptus (Eucalyptus spp.) plants to a wide variety of stress conditions. The objective of this study was to perform data mining to identify favorable genes and alleles associated with the enzyme systems superoxide dismutase, catalase, peroxidases, and glutathione S-transferase that are related to tolerance for environmental stresses and damage caused by pests, diseases, herbicides, and by weeds themselves. This was undertaken by using the eucalyptus expressed-sequence database (https//forests.esalq.usp.br). The alignment results between amino acid and nucleotide sequences indicated that the studied enzymes were adequately represented in the ESTs database of the FORESTs project.  相似文献   
144.
Mercury speciation in fluorescent lamps by thermal release analysis   总被引:4,自引:0,他引:4  
In this work, mercury speciation in phosphorus powder matrices and soda lime glass waste from new and spent fluorescent lamp wastes has been studied by thermo-desorption/atomic absorption spectrometry (TDAAS), X-ray diffraction (XRD), cold vapor-atomic absorption (CV-AAS) and atomic emission spectrometry/inductively coupled plasma (ICP/AES). TDAAS results show the presence of oxidized forms of mercury, i.e., Hg(1+) and Hg(2+), especially in wastes with high mercury concentration. Such forms are mobile, and therefore represent a potential hazard waste material. Glass TD profiles of spent fluorescent lamps suggested the presence of mercury strongly linked to the matrix, which desorbs only at high temperatures.  相似文献   
145.
Environment, Development and Sustainability - This review aimed to analyze plastic lumber manufacturing in Brazil, a country with a large amount of natural wood, and devise strategies to boost...  相似文献   
146.
A field trial was carried out in Brazil in March 2002 with the aim to evaluate the effects of different timing and extension of weedy period on maize productivity. The hybrid Pioneer 30K75 was sowed under 7 t ha(-1) mulching promoted by glyphosate spraying. The treatments were divided in two groups: In the first group, weeds were maintained since the maize sowing until different periods in the crop cycle: 0, 14, 28, 42, 56, 70, and 150 days (harvesting time). In the second group, the maize crop was kept weed free for the same periods of the first group. Weed control was done through hand hoeing. A complete randomized blocks experimental design with five replications was used for plots distribution in the field. Nonlinear regression model was used to study the effects of weedy or weedfree periods on maize productivity. Weed community included 13 families and 31 species. Asteraceae, Poaceae, and Euphorbiaceae were the most abundant families. Results showed that under no tillage condition with 7 t ha(-1) mulching at sowing time, the maize crop could cohabit with weed community for 54 days without any yield lost. On the other hand, if the crop was kept weed free for 27 days, the weed interference was not enable to reduce maize production. According to these results one weed control measure between 27 and 54 days after crop emergence could be enough to avoid any reduction in maize productivity.  相似文献   
147.
In case of an accident at a nuclear power plant with liberation of radioactive material into the atmosphere, knowledge about the behavior of plant species when in contact with radionuclides is indispensable for safety reasons. The leaf-fruit translocation is an important route through which agricultural products are contaminated by radionuclides. To quantify the leaf-fruit translocation factors for 137Cs and 90Sr in common beans (Phaseolus vulgaris) an experiment was carried out in a greenhouse with a randomized block design. 137Cs activity was determined by gamma-ray spectrometry, while chemical separation followed by beta counting of 90Y was used for 90Sr determination. The model applied for translocation indicated functional dependence between the moment of tracer application and the physiological development of the bean plant. Translocation factors obtained for 137Cs and 90Sr were 0.16 and less than 0.005, respectively.  相似文献   
148.
149.
Neurodegenerative diseases are increasingly common in humans. Alzheimer's disease (AD) is a neurodegenerative disease characterized by the presence of extracellular plaques containing β‐amyloid peptides and neurofibrillary tangles in the brains. Researchers have focused on the elucidation of a correlation between high concentrations of aluminum or iron (in the organism with observed neuropathology). The objective of this study was to evaluate the effects of aluminum and iron on the behavioral parameters (pharyngeal pumping and defecation cycle) of the nematode Caenorhabditis elegans pretreated with deferoxamine (DFX). Acetylcholinesterase (AChE) activity was evaluated as well. DFX is a chelant that is widely used for the treatment of metal toxicity, and it has a high affinity for aluminum and iron. The worms were pretreated with DFX, and then exposed to aluminum and iron. In the absence of DFX, aluminum exposure decreased pharyngeal pumping compared with that in the control group. The defecation cycle of the control was significantly different from that of the worms exposed to aluminum. In contrast, an increased defecation cycle was observed in worms exposed to iron without DFX pretreatment. AChE activity increased in aluminum‐exposed groups that received DFX pretreatment compared with those that did not receive pretreatment. These results suggest that pretreatment with DFX is effective in reducing metal toxicity, particularly with reference to AChE activity, which did not decrease in groups that did not receive DFX pretreatment.  相似文献   
150.
Lead (Pb) has been highlighted as a major pollutant of both terrestrial and aquatic ecosystems, causing negative impacts to these environments. The concentration of Pb in plants has increased in recent decades, mainly due to anthropogenic activities. This study has as a hypothesis that the species Oxycaryum cubense (Poep. & Kunth) Palla, abundant in aquatic environments, has the potential to be used a phytoremediator. The plants were grown in a hydroponic system with Pb in increasing concentrations (0, 4, 8, 16 and 32 mg l?1) for 15 days. Inductively coupled mass spectrometer (ICP OES) was used to determine the concentration of mineral nutrients and lead. Optical and transmission electron microscopy were used for the analysis of cellular damage induced by lead in roots and leaves. Ultrastructural alterations were observed as disorganization of thylakoids in the chloroplast and disruption of mitochondrial membranes in cells of leaf tissues of plants subjected to increasing Pb concentrations. There was accumulation of Pb, especially in the root system, affecting the absorption and translocation of some mineral nutrients analysed. In roots, there was reduction in the thickness of the epidermis in plants treated with Pb. This species was shown to be tolerant to the Pb concentrations evaluated, compartmentalizing and accumulating Pb mainly in roots. Due to these results, it may be considered a species with phytoremediation capacity for Pb, with potential rizofiltration of this metallic element in contaminated watersheds.  相似文献   
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