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21.
The global urban population is increasing rapidly, but patterns of urban expansion differ greatly among countries. Urban transition theory predicts that the shift from low to high urbanization depends on a country’s history and level of economic development. This study describes urban expansion in Colombia, Ecuador, Peru, and Bolivia between 1992 and 2009. Urban dynamics were analyzed by combining nighttime lights and census data from 4032 municipalities. High-lit areas (>52–63 pixel values) were correlated with urban populations across municipalities and years (R 2 > 0.90). Analyses showed that between 1992 and 2009 Bolivia and Ecuador had rapid population growth and rapidly increasing high-lit areas, while Peru and Colombia had lower rates of population growth and urbanization (i.e., expansion of high-lit areas). We demonstrate how nighttime lights can be a useful tool, providing a homogeneous platform for multi-scale analyses of urban growth. 相似文献
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Ahmed F Bibi MH Asaeda T Mitchell CP Ishiga H Fukushima T 《Environmental monitoring and assessment》2012,184(7):4383-4396
Bottom sediments from Lake Jinzai in southwest Japan were analyzed to determine their chemical compositions and to assess the potential for ecological harm by comparison with sediment quality guidelines. The pollution status of lake sediments was evaluated by employing contamination factor (CF), pollution load index (PLI), and geoaccumulation index (I(geo)), focusing on a suite of elements in lakebed and core sediments. Elevated concentrations of As, Pb, Zn, Cu, TOC, N, and P were present in several layers of the upper core and other surface sediments. The elevated metal concentrations are likely related to the fine-grained nature of the sediments, reducing bottom conditions produced by abundant organic matter, and possibly minor non-point anthropogenic sources. Moreover, correlations between the concentrations of trace metals and organic carbon, nitrogen, phosphorus, and iron, suggest that these elements play a role in controlling abundances. Calculated CF, PLI, and I(geo) indicate that the sediments are strongly polluted with respect to As, moderately to strongly polluted with Zn, and moderately polluted with Pb and Cu. Metal concentrations exceed the New York State Department of Environmental Conservation (NYSDEC) lowest effect level and the Canadian Council of Ministers of the Environment (CCME) interim sediment quality guidelines that indicate moderate impact on aquatic organisms in the study area. 相似文献
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The Hon Hugh Small 《Natural resources forum》1990,14(2):155-157
Jamaica has developed a new strategy designed to allow it to expand its bauxite and alumina production, to diversify both its markets and its sources of investment and, to move downstream into the production of aluminium and semi-finished products. Some benefits of this new strategy are already evident, several bauxite mines are being expanded, alumina plants are being re-opened while others are adding additional capacity, and the countries of Europe, Asia and North America are showing renewed interest in investing in Jamaica. With its new strategy, Jamaica intends to participate more fully in the world economy. 相似文献
26.
Thomas Carlisle George Mulamoottil Bruce Mitchell 《Journal of the American Water Resources Association》1991,27(3):419-427
ABSTRACT: The objective was to survey individuals from different interest groups in Ontario to ascertain attitudes towards the use of artificial wetlands for stormwater management and to provide waterfowl habitat. In total, 166 questionnaires were distributed and 124 cempleted returns were received. The results of the survey show that the provision of wetlands as waterfowl habitats in the context of stormwater impoundments is severely limited and is not considered an important management option. The overwhelming rejection of this integrated approach seems to be due to a lack of understanding and its comparative newness. Some of the perceived problems and concerns could be addressed by improvements in the design of the artificial wetlands. The design and implementation of an artificial wetland prototype as part of an education program in Ontario is recommended. A few research opportunities also are outlined. 相似文献
27.
Saied Mostaghimi J. Kent Mitchell 《Journal of the American Water Resources Association》1983,19(4):605-612
ABSTRACT Laboratory experiments were conducted to study effects of trickle emitter discharge rate on the distribution of soil moisture in a silty-clay loam soil. Both pulsed and continuous irrigation treatments were studied. A simulation model was used to evaluate the results obtained in the laboratory. The agreement between the predicted and measured soil moisture distribution patterns was quite good. For both pulsed and continuous applications, increasing trickle discharge rate resulted in a decrease in the horizontal component and an increase in the vertical component of the wetted soil profile. Compared to the continuous treatments, pulsed applications resulted in significant reduction in water loss below the root zone. Pulsed applications rates can replace continuous small discharge rates to reduce irrigation water runoff problems on heavy soils and with restricted infiltration allow the use of larger emitter orifices to decrease potential clogging of the trickle system. 相似文献
28.
Vaughan Shilton Paul Giess David Mitchell Craig Williams 《Water, Air, & Soil Pollution: Focus》2002,2(5-6):237-246
Settled dust has been collected inside the main foyers ofthree University buildings in Wolverhampton City Centre,U.K. Two of the three buildings are located in a streetcanyon used almost exclusively by heavy duty dieselvehicles. The dust was collected on adhesive carbonspectro-tabs to be in a form suitable for analysis byscanning electron microscope and energy dispersive X-rayanalysis. Using these analytical techniques, individualparticle analysis was undertaken for morphology andchemistry. Seasonal variations and variations due tolocation were observed in both the morphologicalmeasurements and chemical analysis. Many of the differencesappear attributable to the influence of road traffic, inparticular, the heavy duty diesel vehicles, travellingalong the street canyon. 相似文献
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Resource scarcity,energy use and environmental impact: A case study of the New Bedford,Massachusetts, USA,fisheries 总被引:3,自引:0,他引:3
The commercial fishing fleet in New Bedford, Massachusetts, USA, harvests seafood on George’s Bank, home of one of the nation’s
most productive fisheries. We calculated the energy return on investment (EROI) and carbon intensity of protein harvest in
the New Bedford fisheries from 1968 to 1988. EROI is the ratio of the energy content of the edible fish protein harvested
to the quantity of fossil fuel energy used directly in the harvesting process. Carbon intensity is the quantity of carbon
dioxide (CO2) released (from the burning of fossil fuels) per calorie of edible fish protein harvested. The results show that the EROI
of protein harvest declined from 0.18 to 0.028 from 1968 to 1988, indicating that the energy used to harvest seafood increased
from about 6 to 36 kcal of fuel for each kilocalorie of protein harvested. The quantity of CO2 released per calorie of edible fish protein is a linear function of energy use and therefore increased in a similar manner.
During this period there was a large increase in fishing effort (caused by the increase in the real price of seafood products,
favorable tax treatment for new vessel construction, and low interest loans from the government), and a decline in several
important species of fish. The results suggest that fishing pressure could be managed effectively by the regulation of fuel
use by the fleet. Despite the increase in the price of many seafood products, fishermen absorbed many of the costs of increasing
scarcity in the form of longer working hours and fewer men per vessel. 相似文献