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71.
Many fields of study have employed geophysical islands in experimental design with a great deal of success. An island is a closed and bounded system in many respects and presents a manageable unit of study. The island microcosm has been the basis for significant advances in areas such as evolutionary biology, ecosystem ecology and physical anthropology. The same properties that make islands so useful to scientists present island populations with pressing sustainability challenges of limited resource availability and natural carrying capacity. This paper discusses the characteristics of the island context to show the severity and immediacy of these challenges. Based on this discussion, it is apparent that new approaches are needed to address sustainable development on islands. Island systems and the study of industrial ecology, which examines industry embedded within the finite natural environment, have much to gain from one another in this respect. Several industrial ecology case studies, primarily drawn from research in Puerto Rico, are presented to illustrate the compatibility of islands as a study unit in this field. Industrial ecology presents new solutions to the challenges of sustainable island development, while well‐defined island systems offer a unique opportunity for the approach of industrial ecology.  相似文献   
72.
The response of corticolous lichens, bryophytes, and vascular plants to anthropogenic edges in northern hardwood forest preserves is compared in east-coast and mid-west (NW Minnesota) sites, using micro-epiphytes on red oak (Quercus rubra) and sugar maple (Acer saccharum). The drastically attenuated lichen flora in the east, apparently due to regional air pollution, restricts the usefulness of these bioindicators, even 120 km from New York City. The forest edge is not necessarily equated with increased light. Established edges may have pronounced shoot growth that shades epiphytes. In the absence of air pollution, lichen and bryophyte species exhibit individual responses to light, humidity, and substrate chemistry. Thus summary variables such as total cover or species richness have limited value as bioindicators of forest integrity.  相似文献   
73.
This, our second reply to Östensson, supplements our earlier more technical analysis with a simple intuitive explanation of how investor demand can be driving commodity prices higher even when investor stocks are falling.  相似文献   
74.
In a recent article (Tilton et al., 2011), we argue that even when investor stocks are declining an increase in investor demand can cause a commodity's price to rise, a conclusion that is both contrary to conventional wisdom and counter-intuitive. In his comment on our article, Olle Östensson (2011) challenges this finding. After assessing his concerns in this reply, we maintain that our original finding is valid: investor demand can be driving commodity prices higher even when investor stocks are falling.  相似文献   
75.
Considering growing population and decreasing mineral resource reserves, the issue of undermining has been and shall remain very topical. This study aims to identify the mutual connections between mined out panels of a deposit and the final manifestations on the ground surface related to deep black coal mining. On the grounds of the identified connections, the study describes a method to simplify a common evaluation of undermined areas according to building site categories. Within the study, a demarcation of the areas was conducted in two localities in Czech Republic influenced by the effects of undermining in the Upper-Silesian Basin. In the allotment of the CSM Mine, an area unsuitable for founding structures was defined from the centre of the worked out workings to the distance of 175 m from the panel's edge, for which the corresponding break angle is 78.3°. Similarly, in the allotment of the Paskov Mine, an area unsuitable for founding structures was determined to the distance of 500 m from the panel's edge, for which the corresponding break angle is 50.2°. This demarcation may be implemented prior to deposit mining being aware of several physical-mechanical parameters of rocks in the deposit's overburden. Having mined out a particular section of a deposit, it is recommended to verify the values of break angle using the method described herein. The study may be applied as a relatively fast and effective method to evaluate future land use for planning.  相似文献   
76.
Relatively little is known about exposures to traffic-related particulate matter at schools located in dense urban areas. The purpose of this study was to examine the influences of diesel traffic proximity and intensity on ambient concentrations of fine particulate matter (PM2.5) and black carbon (BC), an indicator of diesel exhaust particles, at New York City (NYC) high schools. Outdoor PM2.5 and BC were monitored continuously for 4–6 weeks at each of 3 NYC schools and 1 suburban school located 40 km upwind of the city. Traffic count data were obtained using an automated traffic counter or video camera. BC concentrations were 2–3 fold higher at urban schools compared with the suburban school, and among the 3 urban schools, BC concentrations were higher at schools located adjacent to highways. PM2.5 concentrations were significantly higher at urban schools than at the suburban school, but concentrations did not vary significantly among urban schools. Both hourly average counts of trucks and buses and meteorological factors such as wind direction, wind speed, and humidity were significantly associated with hourly average ambient BC and PM2.5 concentrations in multivariate regression models. An increase of 443 trucks/buses per hour was associated with a 0.62 μg/m3 increase in hourly average BC at an NYC school located adjacent to a major interstate highway. Car traffic counts were not associated with BC. The results suggest that local diesel vehicle traffic may be important sources of airborne fine particles in dense urban areas and consequently may contribute to local variations in PM2.5 concentrations. In urban areas with higher levels of diesel traffic, local, neighborhood-scale monitoring of pollutants such as BC, which compared to PM2.5, is a more specific indicator of diesel exhaust particles, may more accurately represent population exposures.  相似文献   
77.
Fine root dynamics (diameter < 1 mm) in mature Fagus sylvatica, with the canopies exposed to ambient or twice-ambient ozone concentrations, were investigated throughout 2004. The focus was on the seasonal timing and extent of fine root dynamics (growth, mortality) in relation to the soil environment (water content, temperature). Under ambient ozone concentrations, a significant relationship was found between fine root turnover and soil environmental changes indicating accelerated fine root turnover under favourable soil conditions. In contrast, under elevated ozone, this relationship vanished as the result of an altered temporal pattern of fine root growth. Fine root survival and turnover rate did not differ significantly between the different ozone regimes, although a delay in current-year fine root shedding was found under the elevated ozone concentrations. The data indicate that increasing tropospheric ozone levels can alter the timing of fine root turnover in mature F. sylvatica but do not affect the turnover rate.  相似文献   
78.
79.
Marian Lydall   《Resources Policy》2009,34(3):112-120
Backward linkages refer to the various inter-firm relationships connecting an industry with its supply chain. Demand–supply interactions between producer firms and suppliers of original equipment, strategic inputs, components and specialised services have played an important role in the evolution of the South African mining sector, contributing indirectly to employment creation, new business growth and expansion, improved efficiency of mining operations, and new knowledge generation. This paper presents a case study of backward linkage development in the South African platinum group metals (PGM) industry and draws on the findings from a quantitative and qualitative analysis of the sector undertaken in 2007. A profile of the supply chain is provided and an assessment made of the strength and sustainability of existing linkages.  相似文献   
80.
Atmospheric particulate matter (PM) is hypothesized to increase the risk of myocardial infarction (MI). However, the epidemiological evidence is inconsistent. We identified 33 studies with more than 4 million MI patients and applied meta-analysis and meta-regression to assess the available evidence. Twenty-five studies presented the effects of the PM level on hospitalization for MI patients, while eight studies showed the effects on mortality. An increase in PM10 was associated with hospitalization and mortality in myocardial infarction patients (RR per 10 μg/m3?=?1.011, 95 % CI 1.006–1.016; RR per 10 μg/m3?=?1.008, 95 % CI 1.004–1.012, respectively); PM2.5 also increased the risk of hospitalization and mortality in MI patients (RR per 10 μg/m3?=?1.024, 95 % CI 1.007–1.041 for hospitalization and RR per 10 μg/m3?=?1.012, 95 % CI 1.010–1.015 for mortality). The results of the cumulative meta-analysis indicated that PM10 and PM2.5 were associated with myocardial infarctionwith the addition of new studies each year. In conclusion, short-term exposure to high PM10 and PM2.5 levels revealed to increase risk of hospitalization and mortality for myocardial infarction. Policy support of pollution control and individual protection was strongly recommended.  相似文献   
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