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1.
The recycling of scrap material has been identified as an important strategy in the larger theory of industrial ecology. Industrial ecology argues that the traditional model of industrial activity needs to be transformed into a 'closed loop' industrial ecosystem where used materials (scrap) and by-products would substitute for virgin materials during production processes. The recycling of scrap material forms part of this larger effort to reduce the overall environmental impact of production and consumption. A key, but as yet, unresolved question in this process is the geographic scale (local, regional, national, global) at which loop closing should take place. This preliminary empirical research examines the export and import geography of the seven largest (by weight) US scrap commodities (iron and steel, paper, plastics, aluminium, copper, nickel and zinc) between 1995 and 2005 to ascertain the extent to which US scrap flows overseas and how that might affect our understanding of how material loops can close. Other than an integrated export and import relationship with Canada, the results suggest that there are two distinct circuits of scrap flows in the USA. The USA exports a substantial portion of the recyclable scrap generated each year to rapidly developing countries, while importing smaller quantities of scrap from the EU. With the major exception of exporting higher value iron and steel scrap to China, the US tends to export lower value scrap and import higher value scrap. In part this reflects imbalances in the supply and demand for scrap between the USA and the developing world, the lack of potentially available scrap and the absence of a robust recycling infrastructure in the developing world. Although such scrap circuits are probably not ideal, the use of US scrap in the developing world is both a realistic and preferable alternative in the short to medium term than virgin production. 相似文献
2.
David Pimentel 《Natural Resources Research》2003,12(2):127-134
Several studies suggest that the $1.4 billion in government subsidies are encouraging the ethanol program without substantial benefits to the U.S. economy. Large ethanol industries and a few U.S. government agencies, such as the USDA, support the production of ethanol. Corn-farmers receive minimal profits. In the U.S. ethanol system, considerably more energy, including high-grade fossil fuel, is required to produce ethanol than is available in the energy-ethanol output. Specifically about 29% more energy is used to produce a gallon of ethanol than the energy in a gallon of ethanol. Fossil energy powers corn production and the fermentation/distillation processes. Increasing subsidized ethanol production will take more feed from livestock production, and is estimated to currently cost consumers an additional $1 billion per year. Ethanol production increases environmental degradation. Corn production causes more total soil erosion than any other crop. Also, corn production uses more insecticides, herbicides, and nitrogen fertilizers than any other crop. All these factors degrade the agricultural and natural environment and contribute to water pollution and air pollution. Increasing the cost of food and diverting human food resources to the costly inefficient production of ethanol fuel raise major ethical questions. These occur at a time when more than half of the world's population is malnourished. The ethical priority for corn and other food crops should be for food and feed. Subsidized ethanol produced from U.S. corn is not a renewable energy source. 相似文献
3.
生物质能源生产的生态环境影响(英文) 总被引：1，自引：0，他引：1
生物质能源生产是能源发展领域的重大挑战,在解决新的替代能源中扮演着重要角色。本文着重论述了美国生物能源生产的生态环境问题。从经济、环境和战略方面考虑,生物能源有望提高国家安全,因而受政策驱动的美国生物能源生产技术备受注目。尽管生物能源具有诸多潜在效益,但是在北美,生物原料供应、高强度经营的土地上农药使用及其对陆地野生动物的潜在影响等令人担忧,我们分析了其中的原因。通常认为,未来生物能源的环境、经济效应是正面的;然而,谨慎地审视和发展生物能源经济以保护生态系统的可持续性显得至关重要。 相似文献
4.
Ethanol Production: Energy and Economic Issues Related to U.S. and Brazilian Sugarcane 总被引：1，自引：0，他引：1
For a thorough and up-to-date evaluation of all the fossil energy costs of ethanol production from sugarcane in both the U.S.
and Brazil, every energy input in the biomass production and ultimate conversion process must be included. In this study,
more than 12 energy inputs in average U.S. and Brazilian sugarcane production are evaluated. Then in the fermentation/distillation
operation, nine more fossil fuel inputs are identified and included. Some energy and economic credits are given for the bagasse
to reduce the energy inputs required for steam and electricity. Based on all the fossil energy inputs in U.S. sugarcane conversion
process, a total of 1.12 kcal of ethanol is produced per 1 kcal of fossil energy expended. In Brazil a total of 1.38 kcal
of ethanol is produced per 1 kcal of fossil energy expended. Some pro-ethanol investigators have overlooked various energy
inputs in U.S. and Brazilian sugarcane production, including farm labor, farm machinery, processing machinery, and others.
In other studies, unrealistic low energy costs were attributed to such energy inputs, as nitrogen fertilizer, insecticides,
and herbicides. Both the U.S. and Brazil heavily subsidize ethanol production. Thus billions of dollars are invested in subsidies
and this significantly increases the costs to the consumers. The environmental costs associated with producing ethanol in
the U.S. and Brazil are significant but have been generally overlooked. The negative environmental impacts on the availability
of cropland and freshwater, as well as on air pollution and public health, have yet to be carefully assessed. These environmental
costs in terms of energy and economics should be calculated and included in future ethanol analyses so that sound assessments
can be made. In addition, the production of ethanol in the U.S. and Brazil further confirms that the mission of converting
biomass into ethanol will not replace oil. This mission is impossible. General concern has been expressed about taking food
crops to produce ethanol for burning in automobiles instead of using these crops as food for the many malnourished people
in the world. The World Health Organization reports that more than 3.7 billion humans are currently malnourished in the world—the
largest number of malnourished ever in history. 相似文献
5.
Fertilizer use by U.S. agriculture has increased over the past few decades. The production and transportation of fertilizers (nitrogen, N; phosphorus, P; potassium, K) are energy intensive. In general, about a third of the total energy input to crop production goes to the production of fertilizers, one-third to mechanization, and one-third to other inputs including labor, transportation, pesticides, and electricity. For some crops, fertilizer is the largest proportion of total energy inputs. Energy required for the production and transportation of fertilizers, as a percentage of total energy input, was determined for 16 crops in the U.S. to be: 19–60% for seven grains, 10–41% for two oilseeds, 25% for potatoes, 12–30% for three vegetables, 2–23% for two fruits, and 3% for dry beans. The harvested-area weighted-average of the fraction of crop fertilizer energy to the total input energy was 28%. The current sources of fertilizers for U.S. agriculture are dependent on imports, availability of natural gas, or limited mineral resources. Given these dependencies plus the high energy costs for fertilizers, an integrated approach for their efficient and sustainable use is needed that will simultaneously maintain or increase crop yields and food quality while decreasing adverse impacts on the environment. 相似文献
6.
Saul B. Suslick 《Natural Resources Research》1998,7(3):211-224
This paper presents a methodology used to combine energy and mineral market variables between Less Developed Countries (LDCs)
and Developed Countries (OECD) over the past 24 years (1966–1990). LDCs include all countries, except OECD and central planned
economies (CIS) and other countries in Eastern Europe. This period permits a comprehensive view of the impact of the energy
crisis and the changes in economic growth patterns, correlated with changes in trends of production and consumption of energy
and metals in both country blocs. This complex relationship was evaluated by a factor model of consumption and production
variables using the aluminum, copper, lead, and zinc industries. The following variables are used in the factor model: export
dependence, geographic concentration of mining production, geographic concentration of refined demand, geographic concentration
of refined production, import dependence, refined demand growth, stability of demand, income elasticity of refined demand,
price stability, intensity of use, and intensity of energy. The model for all commodities shows that the factor scores projections
for LDCs and OECD blocs depicted a clearly divergent trend after the two oil shocks (1973–1979), when the intensity of energy
variable presents high loading in the factor. The results are in substantial agreement with findings that the demand for energy,
as well as for metals, is growing more rapidly in LDCs than OECD. 相似文献
7.
K. Bruce Newbold 《The Professional geographer》1997,49(1):1-14
This paper uses the U.S. 1990 Public Use Micro Sample to characterize the 1985-1990 primary, return, and onward interstate migration patterns for blacks and whites. The classification of these three types of migration is based on the state of birth and state of residence at the start and end of the census interval. Major migration streams, migration rates, and net migration are evaluated for each migrant type and compared for blacks and whites. Overall, the migration patterns of blacks resemble those of whites, with an attraction to the South and the Southwest and movement out of the Northeast and the Midwest. Some differences were observed, however, between the two races. Return migration rates were somewhat higher for black migrants as compared with whites, and onward migration rates were lower. Black primary out-migrants represented a larger proportion of the total flows from the southern states as compared with white out-migrant flows, and they represented a larger share of the out-migrants from the rust belt states. The major migration streams also had different regional and national patterns by race and migrant type. 相似文献
8.
In this paper, the life cycle assessment (LCA) method is used to evaluate and quantify the energy consumption and environmental impacts of biodegradable polylactic acid (PLA) plastic packaging from the five stages of raw material acquisition, raw material transportation, product production, products use and final disposal. Seven impact categories were selected for the impact analysis: abiotic depletion potential fossil fuels (ADP), global warming potential (GWP), acidification potential (AP), eutrophication potential (EP), photochemical ozone formation potential (POCP), human toxicity potential (HTP), and terrestrial ecotoxicity potential (TETP). The results of the LCA are discussed and the results show that production of products is the highest stage of the environmental impact. Meanwhile, in the entire life cycle, the top three environmental impact categories are GWP, ADP and HTP, which account for 32.63%, 24.83% and 14.01%, respectively. The LCA results show that the environmental impact can be reduced in several ways: reducing the consumption of electricity, increasing the input of new energy, increasing the conversion rate of materials in the production process, using organic and water-soluble fertilizers instead of conventional fertilizers, using environment-friendly fuels and establishing a sound recycling system. 相似文献
9.
区域碳排放时空格局及其关键影响因素是近年来学者们关注的热点。本文以中国经济发达、经济关联密切、产业格局变化剧烈的泛长三角地区为案例,分析1990年以来典型年份碳排放的空间分异、时间演变,解析碳排放空间分异的关键影响因素。结果表明：①区域碳排放总量快速增长,总体格局稳中有变,核心区16个城市排放量占比大都超过50%。②以2005年为拐点,之前外围城市增长幅度较低,之后外围城市碳排放量快速增长;外围地区碳排放量占比从2005年的33%快速增加至2014年的47%,区域碳排放量的空间集聚度呈现先增后减的态势。③碳排放格局变化受多种因素影响,不同变量对碳排放的影响各异。其中,工业生产、城镇化建设及人口集聚仍是现阶段泛长三角地区最主要的碳排放来源;固定资产与外商投资对区域碳排放的作用呈增强趋势,但其作用强度较工业生产、城镇化建设、人口集聚要小。地区生产总值对碳排放影响存在倒U型关系,随着经济发展水平的提高,碳排放与经济发展呈现脱钩趋势。研究结果可为揭示经济发展格局变化的环境效应、制定节能减排政策提供参考。 相似文献
10.
Pierce Greenberg 《社会与自然资源》2018,31(9):995-1011
Resource-dependent communities are subject to both unstable economic patterns and environmental degradation associated with extractive industries. However, few studies have empirically analyzed these dynamics in tandem and over time. This paper explores whether Appalachian neighborhoods closer to coal waste impoundments experienced steeper poverty changes from 1990 to 2000. Impoundment failures have resulted in some of the largest environmental disasters in U.S. history and scientists have expressed concerns over their growing heights and risks. Spatial regression models show that neighborhoods closer to impoundments have higher poverty increases on average, even after controlling for mining employment and other variables. These findings highlight the need for a deeper consideration of the environmental inequalities associated with the continued downturn of coal production and employment in the United States. Further, discussions about just transitions must recognize the legacy hazards and externalities associated with extractive industries – and their impacts on communities. 相似文献
11.
Interstate migration exchanges in the United States are temporally and spatially transitory. Both the early and mid-1980s exhibited significant fluctuations in the origins and destinations of U.S. migrants, while the late 1980s and early 1990s were even more unstable. Regions once favored by interstate movers such as the West and the South, while remaining attractive, showed evidence of declining favor in the early 1990s. Meanwhile, numerous states in the national interior regained their attractiveness, including several that gained net migrants for the first time in decades. California exhibited a major turnaround in its migration, perturbing the entire U.S. migration system. 相似文献
12.
The geological coal resource of the U.S. is abundant and proved coal reserves are listed as the world’s largest. However, the reserves are unevenly distributed and located in a small number of states, giving them major influence over future production. A long history of coal mining provides detailed time series of production and reserve estimates, which can be used to identify historical trends. In reviewing the historical evolution of coal reserves, one can state that the trend here does not point toward any major increases in available recoverable reserves; rather the opposite is true due to restrictions and increased focus on environmental impacts from coal extraction. Future coal production will not be entirely determined by what is geologically available, but rather by the fraction of that amount that is practically recoverable. Consequently, the historical trend toward reduced recoverable amounts is likely to continue into the future, with even stricter regulations imposed by increased environmental concern. Long-term outlooks can be created in many ways, but ultimately the production must be limited by recoverable volumes since coal is a finite resource. The geologic amounts of coal are of much less importance to future production than the practically recoverable volumes. The geological coal supply might be vast, but the important question is how large the share that can be extracted under present restrictions are and how those restrictions will develop in the future. Production limitations might therefore appear much sooner than previously expected. 相似文献
13.
The quantity and spatial pattern of farmland has changed in China, which has led to a major change in the production potential under the influence of the national project of ecological environmental protection and rapid economic growth during 1990-2010. In this study, the production potential in China was calculated based on meteorological, terrain elevation, soil and land-use data from 1990, 2000 and 2010 using the Global Agro-ecological Zones model. Then, changes in the production potential in response to farmland changes from 1990 to 2010 were subsequently analyzed. The main conclusions were the following. First, the total production potential was 1.055 billion tons in China in 2010. Moreover, the average production potential was 7614 kg/ha and showed tremendous heterogeneity in spatial pattern. Total production in eastern China was high, whereas that in northwestern China was low. The regions with high per unit production potential were mainly distributed over southern China and the middle and lower reaches of the Yangtze River. Second, the obvious spatiotemporal heterogeneity in farmland changes from 1990 to 2010 had a significant influence on the production potential in China. The total production potential decreased in southern China and increased in northern China. Furthermore, the center of growth of the production potential moved gradually from northeastern China to northwestern China. The net decrease in the production potential was 2.97 million tons, which occupied 0.29% of the national total actual production in 2010. Third, obvious differences in the production potential in response to farmland changes from 1990 to 2000 and from 2000 to 2010 were detected. The net increase in the production potential during the first decade was 10.11 million tons and mainly distributed in the Northeast China Plain and the arid and semi-arid regions of northern China. The net decrease in the production potential during the next decade was 13.08 million tons and primarily distributed in the middle and lower reaches of the Yangtze River region and the Huang-Huai-Hai Plain. In general, the reason for the increase in the production potential during the past two decades might be due to the reclamation of grasslands, woodlands and unused land, and the reason for the decrease in the production potential might be urbanization that occupied the farmland and Green for Grain Project, which returned farmland to forests and grasslands. 相似文献
14.
Kathi Wilson 《The Professional geographer》2013,65(1):133-134
This paper expands the human capital model to compare the migration propensities of Cubans, Mexicans, and Puerto Ricans within the U.S. between 1985 and 1990. Using the 5% PUMS from the 1990 U.S. Census, both aggregate migration streams and micro-level migration propensities are estimated for Cubans, Mexicans, and Puerto Ricans. The effects of personal factors, the economic environment, and the presence of fellow nationals are examined in the context of larger geographic patterns, and discussed in terms of each nationality's immigration history and cultural context. While many factors effect migration behavior similarly, there are notable differences in the way education, English fluency, and unemployment rate affect migration propensity of the native-born and foreign-born of each nationality. Differences are also apparent at the macro-level. Puerto Ricans show signs of dispersing out of New York; Mexicans are redistributing within the Southwest; and Cubans are re-concentrating in Florida. Both levels of analysis point to how immigration history, settlement patterns, and cultural context influence migration behavior. The results demonstrate the benefits of using an expanded human capital approach to explain migration differences, and highlight the diversity of population redistribution occurring within Hispanic nationalities. 相似文献
15.
Danilo J. Santini 《Natural Resources Research》1998,7(2):101-121
This paper examines three issues related to both the U.S. and world oil supply: (1) the nature of the long-term, postpeak
production profile for the U.S. and, by inference, other regions (the Hubbert curve is used as a “strawman” model); (2) implications
on U.S. energy security of using a modified Hubbert-type conceptual model of prepeak production, testing the adequacy of Latin
America to be the primary source of U.S. oil imports; and (3) the cyclic behavior of oil prices. it shows that U.S. production
will exhibit a more attenuated decline than that simulated by the Hubbert curve and not decline to zero. it asserts that U.S.
production is better predicted by past reserves than past production, but that this argument does not apply to nations that
keep a much larger proportion of reserves in the ground. Such nations could considerably expand production without any growth
in reserves. The paper concedes that the potential total production for these nations could be examined with a Hubbert curve
model linked to reserves, but with great uncertainty. Such an uncertain optimistic forecast predicts that the cumulative production
of Latin America could far exceed that of the United States. Nevertheless, a statistical model of oil prices since 1870 implies
that real wellhead oil prices in the United States are on a long-term upward path, underlying a much more “noisy” cyclical
pattern estimated to include 22- and 27-year cycles. The statistical model predicts a severe oil shock within a few years
(of 1998) but also predicts that through 2030, real oil prices will not reach 1981 levels again. The paper examines U.S. and
world trends in seismic exploration, drilling locations and depths, drilling costs, oil/gas reserves, oil/gas use rates, and
oil demand. After taking these factors into consideration, it concludes that the statistical model of oil prices cannot be
disputed, despite its lack of basis in economic theory. 相似文献
16.
Fasong Yuan 《Journal of Paleolimnology》2017,58(1):23-42
Concentrations of aluminum, arsenic, barium, beryllium, cadmium, calcium, chromium, cobalt, copper, iron, lead, magnesium, manganese, molybdenum, nickel, potassium, selenium, sodium, tin, titanium, vanadium, and zinc were measured in a surface sediment core from the Sandusky basin of Lake Erie to detail the history of hydrological and environmental changes back to 1800. The results from hierarchical cluster and principal component analyses revealed four elemental groups. All the trace elements clustering with aluminum, iron, and manganese in Group I were enriched due to increased inputs from anthropogenic sources. The two conservative elements sodium and potassium clustering in Group II showed patterns of changes like those of water-level fluctuations. The two carbonate elements calcium and magnesium clustering in Group III showed intriguing but complex carbonate biogeochemistry associated with biogenic production, organic acid-induced dissolution and dilution by organic and aluminosilicate materials. The terrigenous element titanium in Group IV experienced two stages of depletion from increased organic fluxes in the 1820s and 1950s. Following the enactments of stringent regulations in the early 1970s, many of these elemental inputs have reduced considerably. But the concurrent reductions in the Sandusky basin were much slower than previously thought. Large increases in inputs from local storages (internal loading) were required to account for the slow reductions. The increased internal loading was caused by augmented organic materials from accelerated eutrophication which facilitated the transfer, transport, and cycling of many trace metals. This work has implications in ongoing research efforts to tackle the eutrophication problem because the complex ecosystem including the internal loading has changed considerably over the past two centuries. 相似文献
17.
This paper expands the human capital model to compare the migration propensities of Cubans, Mexicans, and Puerto Ricans within the U.S. between 1985 and 1990. Using the 5% PUMS from the 1990 U.S. Census, both aggregate migration streams and micro‐level migration propensities are estimated for Cubans, Mexicans, and Puerto Ricans. The effects of personal factors, the economic environment, and the presence of fellow nationals are examined in the context of larger geographic patterns, and discussed in terms of each nationality's immigration history and cultural context. While many factors effect migration behavior similarly, there are notable differences in the way education, English fluency, and unemployment rate affect migration propensity of the native‐born and foreign‐born of each nationality. Differences are also apparent at the macro‐level. Puerto Ricans show signs of dispersing out of New York; Mexicans are redistributing within the Southwest; and Cubans are re‐concentrating in Florida. Both levels of analysis point to how immigration history, settlement patterns, and cultural context influence migration behavior. The results demonstrate the benefits of using an expanded human capital approach to explain migration differences, and highlight the diversity of population redistribution occurring within Hispanic nationalities. 相似文献
18.
A new method for short- and long-term forecasting of mineral commodities based upon historical data is developed. The method, referred to as the latest trend tracing (LTT) model, is constructed as a weighting and adaptive approach based on a general linear model. The LTT model considers the functions of data location and statistical behavior. The newest data receive the largest weights, whereas the older data are given smaller weights. The LTT model is performed by an iterative algorithm. The data set is successively partitioned into training and testing subsets. Each LTT model is estimated and tested for each partition. The updated estimates are then synthesized to produce the final estimates based upon the data locations and estimation variances. The LTT model is demonstrated on two real case studies, one on the projection of U.S. aluminum consumption and the other on the forecasting of U.S. copper consumption. 相似文献
19.
Taneomi Harada 《Natural Resources Research》1993,2(3):247-255
Resource recycling reduces the amount of waste discharged into the global environment. The waste reduction achieved by thorough recycling is substantial. Recycling is thus an inseparable part of global environmental protection.We human beings have used mineral resources since the birth of our species. The quantities and increasingly complex forms in which mineral resources have been used at different times in our prehistory and history serve as indices of civilization's advancement. But on the eve of the 21st century, environmental pollution and global warming stemming from spiraling resource and energy consumption pose serious dilemmas for humanity. The rapidity with which our resource consumption has increased approximates exponential growth.The worsening condition of the earth's environment because of massive resource and energy consumption is the result of activity at many stages of production, from the mining of mineral resources to the manufacture of finished products; the culmination of the process is the disposal of products as waste after their use. As we shall see from examples given in this paper, efforts are being made to solve this problem through recycling; but in many areas the problems remain incompletely solved or unsolved altogether. 相似文献
20.
Kansas produces both conventional energy (oil, gas, and coal) and nonconventional (coalbed gas, wind, hydropower, nuclear,
geothermal, solar, and biofuels) and ranks the 22nd in state energy production in the U.S. Nonrenewable conventional petroleum
is the most important energy source with nonrenewable, nonconventional coalbed methane gas becoming increasingly important.
Many stratigraphic units produce oil and/or gas somewhere in the state with the exception of the Salina Basin in north-central
Kansas. Coalbed methane is produced from shallow wells drilled into the thin coal units in southeastern Kansas. At present,
only two surface coal mines are active in southeastern Kansas. Although Kansas has been a major exporter of energy in the
past (it ranked first in oil production in 1916), now, it is an energy importer. 相似文献