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211.
Meneses M  Schuhmacher M  Domingo JL 《Chemosphere》2002,46(9-10):1393-1402
The vegetation and soil levels of the 17 polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/F) toxic congeners were calculated by means of a vegetation and a soil model, respectively. Both models predicted the levels of the 17 PCDD/F congeners in quite good agreement with the observed results although the soil model was more accurate than the vegetation model. Four different pathways of contribution to the vegetation concentrations were taken into account: vapour-phase absorption, dry particle deposition, wet particle deposition and uptake by root. The most important pathway was the vapour-phase absorption and the less was the uptake by root. In the soils model four pathways were considered: background soil concentration, dry particle deposition, wet particle deposition and uptake by root. After the background concentration, the most important pathway was the wet deposition.  相似文献   
212.
Introduction. The strong physical demands that are required of lifeguards during rescues also require an accurate self-perception of one's fitness level to be able to regulate the intensity of effort. Objectives. The aim of this study was to determine the real aerobic capacity (RAC) and to compare it with two self-reported measurements: subjective appraisal of aerobic capacity (SAAC) and appraisal of physical exercise (APE). Methods. Fifty-two professional lifeguards were included in the study. For an objective assessment of RAC, the lifeguards’ maximum oxygen uptake (VO2max) values were measured during treadmill stress tests. A fitness assessment questionnaire was used to obtain the SAAC and APE values. Results. We found a statistically significant association between the APE and RAC variables in the contingency analysis (p?VO2max value below 43 ml kg?1?min?1 considered their aerobic capacity to be high or very high. Conclusion. This self-perception error of true aerobic capacity could lead to premature fatigue during a rescue, endangering both the lifeguard's life and the life of the victim. These data may help lifeguards and beach managers to become aware of the need to know lifeguards’ true physical conditions through testing and structured training programs.  相似文献   
213.
This article presents a systematic literature review of 109 articles (1992–2015) dealing with Local Agenda 21 processes worldwide. It analyzes two essential elements of Local Agenda 21: (1) the holistic approach of the sustainable development concept and (2) the main driving forces behind such processes. It shows that, although at the beginning, sustainability was seen as a natural extension of environmental policy work, it has been perceived over recent years as a guiding principle applied to issues of environment, economic development, and social welfare, and Local Agenda 21 is perceived as a coherent approach to sustainability planning. In addition, Local Government Strategy is the main typology followed, although it suffers from important limitations. Future studies could focus on local sustainability process outcomes. Further quantitative studies would be welcome, given the qualitative case study dominance in the field. We conclude with a research agenda to tackle theoretical, methodological, and empirical lacunae.  相似文献   
214.
Established research in first world urban environments has shown street sediments to be effective sinks for heavy metals and emphasises the health risks to children by its inhalation or ingestion. In third world countries with fewer pollution controls, contamination may be augmented by additional pollutants such as sewage discharge into urban streets and/or periodic inundation with sewage-laden run-off. This pollutant not only contains heavy metals and organic matter, but calcium oxalates that may derive directly from the sewage itself. To study this premise street sediments were collected from sites of varying industrialisation and sewage contamination within the city of Niteroi, Brazil. Calcium oxalate dihydrate (weddellite) was identified by X-ray diffraction, fourier transform infra red and scanning electron microscopy techniques and oxalate concentrations in <63m and colloidal (clay and organic matter) fractions, were determined by ion chromatography. Oxalate in colloidal fractions averaged 43601mgkg–1 in sewage contaminated industrialised urban zones, 4519mgkg–1 in suburban areas and 17477mgkg–1 in suburbs with favelas (shantytowns-of Niterói). Oxalate concentrations coincide with high levels of metal ions (Fe, Mn, Zn, Pb, Ni, Cr) that stabilise calcium oxalate dihydrate and prevent its dehydration to the monohydrate (whewellite). Lower levels of oxalate were found in lichen-covered roof sediment, plaster and mortar samples. Oxalate concentration coincides with sewage contamination and street sediments appear to act as a sink for calcium oxalate dihydrate derived from sewage. Previous studies have shown that low levels of exposure can damage kidneys and the nervous system, while prolonged exposure can cause severe corneal, retinal and skin damage, cyanosis and possibly gangrene. Contact with blood serum may result in hypocalcemia, muscular stimulation, convulsions and finally collapse. The conditions described are common throughout urban areas of the developing world and may suggest a particular environmental hazard in these regions.  相似文献   
215.
本研究的目的是调查巴西亚马孙河流域森林砍伐对臭氧动力学特征及沉积作用的影响,为此,我们分析了一个森林砍伐场区雨季的臭氧水平和沉积速率,并将这些数据与森林中的类似数据进行了对比.牧场的最大臭氧混合比达到20ppbv,而森林的最大臭氧混合比一般为6ppbv.牧场的最大臭氧沉积速率为0.7 cm/s,而森林的最大臭氧沉积速度大约相当于牧场的三倍.将臭氧丰度与沉积速度结合起来考虑时发现,牧场的最大臭氧通量大约为0.2μg(臭氧)/m2@s.此通量大约代表着森林测得的沉积率的70%.因此,本研究证明,若将雨林转换成牧场,最终可能使亚马孙河流域的臭氧汇(ozone sink)净减少30%.  相似文献   
216.
Atelosteogenesis type II is a lethal chondrodysplasia characterized by severe micromelia, spinal abnormalities, talipes equinovarus, and abducted thumbs and toes. We present a case diagnosed at 21 weeks of gestation in which antenatal sonographic and post-mortem radiological findings were correlated. The patient had a recurrence of this disorder in a subsequent pregnancy which was terminated at 15 weeks, supporting previous reports of an autosomal recessive inheritance pattern. The feasibility of diagnosing the following morphological features by prenatal ultrasonography is demonstrated: coronal clefts of the vertebral bodies, metaphyseal and epiphyseal abnormalities, spinal deviations such as cervical kyphosis and a horizontal sacrum, additional ossification centres in the pelvis, and preaxial deviation of the thumbs and toes. The differential diagnosis of this disorder from other skeletal dysplasias with similar features is discussed.  相似文献   
217.
ABSTRACT: Increasing awareness about the problems brought on by urban sprawl has led to proactive measures to guide future development. Such efforts have largely been grouped under the term “Smart Growth.” Although not widely recognized as such, the “smart” in Smart Growth implies an optimization of some quantity or objective while undertaking new forms of urban development. In this study, we define Smart Growth as that development plan that leads to the optimal value of a precisely defined measure identified by a stakeholder or stakeholders. To illustrate a formal, quantitative framework for Smart Growth, this study develops definitions of optimal development from the perspectives of four different types of stakeholders: a government planner, a land developer, a hydrologist, and a conservationist subject to certain development constraints. Four different objective functions are posed that are consistent with each of these stakeholders’perspectives. We illustrate the differences in consequences on future development given these different objective functions in a stylized representation for Montgomery County, Maryland. Solutions to Smart Growth from the individual perspectives vary considerably. Tradeoff tables are presented that illustrate the consequences experienced by each stakeholder depending on the viewpoint that has been optimized. Although couched in the context of an illustrative example, this study emphasizes the need to apply rigorous, quantitative tools in a meaningful framework to address Smart Growth. The result is a tool that a range of parties can use to plan future development in ways that are environmentally and fiscally responsible and economically viable.  相似文献   
218.
We studied the demographic responses of Ceriodaphnia dubia exposed to copper at 3 different levels (0.1, 0.2 and 0.4 mg l(-1)) and at 4 exposure periods (3, 6, 12 and 24 hr) in addition to controls (without the heavy metal). The tested levels of Cu concentration and the chosen periods of exposure affected some demographic variables (average lifespan, gross and net reproductive rates and generation time). Depending on the heavy metal concentration and the period of exposure, the average lifespan of C. dubia varied from 18 to 24 day Net reproductive rates (NRR) ranged from 50 to 80 offspring per female per lifespan, while the rate of population increase (r) varied from 0.30 to 0.34 per day Though gross reproductive rates (especially at low and intermediate copper levels and shorter duration of exposure) showed significantly higher values than controls, both NRR and r were either unaffected or decreased. It is therefore necessary to regulate the release of untreated industrial effluents containing copper into freshwater ecosystems. Our study thus highlights the importance of including, not only toxicant concentrations but also exposure time, in ecotoxicological evaluations.  相似文献   
219.
Surface sediments were collected from the shore and lagoons of Kavaratti, Kadamat Agatti and Pitti islands of Lakshadweep Archipelago during May 2015 and analysed for biochemical composition and quality of organic matter. The biochemical composition of sedimentary organic matter from the entire study area was characterised by the dominance of carbohydrates (CHO) followed by proteins (PRT) and finally lipids (LPD). PRT:CHO ratios were less than 1 and indicated the presence of aged organic matter in the islands. The poor nutritional quality of sediments to support benthic fauna was evident from the values of LPD:CHO ratios. The refractory nature of sediments and less availability of food to benthic source was supported by BPC:TOC ratios. Based on estimated ratios and biopolymeric carbon values, the trophic status of the study area was categorised as oligotrophic.  相似文献   
220.
A framework to measure safety culture maturity in the Brazilian oil and gas companies was formulated based on the model of Hudson (2001). Following a review of the safety culture literature, a questionnaire was designed to measure five aspects of organisational safety indicative of five levels of cultural maturity. The questionnaire was completed by the safety managers of 23 petrochemical companies based in Camacari, Bahia, Brazil and they were interviewed one month later. The reliability of the questionnaire was tested by asking the same questions in an interview and comparing the results (alternate forms reliability). The correlation coefficients between the questionnaire and interview scores on each dimension ranged from r = 0.7 to 0.9, demonstrating good reliability of the measures used. The research findings demonstrated that the 23 companies studied showed characteristics of different levels of safety culture maturity. Most scores were at the level of proactive. The model of Hudson (2001) and the revised framework and questionnaire were found to be practical to use, making it possible to identify levels of safety culture maturity in the context of the Brazilian petrochemical industry.  相似文献   
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